Accepted Manuscript

Title: Oral health-related quality of life in subjects with

implant-supported prostheses: A systematic review

Authors: Daniel R. Reissmann, Michel Dard, Ragna

Lamprecht, Julia Struppek, Guido Heydecke

PII: S0300-5712(17)30185-9
DOI: http://dx.doi.org/doi:10.1016/j.jdent.2017.08.003
Reference: JJOD 2817

To appear in: Journal of Dentistry

Received date: 21-2-2017

Revised date: 9-7-2017
Accepted date: 2-8-2017

Please cite this article as: Reissmann Daniel R, Dard Michel, Lamprecht Ragna,
Struppek Julia, Heydecke Guido.Oral health-related quality of life in subjects
with implant-supported prostheses: A systematic review.Journal of Dentistry
http://dx.doi.org/10.1016/j.jdent.2017.08.003

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Oral health-related quality of life in subjects with implant-
supported prostheses: A systematic review
Daniel R Reissmanna*, Michel Dardb, Ragna Lamprechtc, Julia Struppekc, Guido Heydecked
*
Corresponding author
a
Associate Professor, Department of Prosthetic Dentistry, Center for Dental and Oral Medicine,
University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany. Tel:
+49-40-7410-54658; Fax: +49-40-7410-57077; Email: d.reissmann@uke.de
b
Adjunct Assistant Professor, Department of Periodontology and Implant Dentistry, College
of Dentistry, New York University, New York, USA and Institut Straumann AG, Basel,
Switzerland
c
Assistant Professor, Department of Prosthetic Dentistry, Center for Dental and Oral
Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
d
Professor and Chair, Department of Prosthetic Dentistry, University Medical Center
Hamburg-Eppendorf, Hamburg, Germany

Short title: Dental implants and quality of life

Abstract
Objectives: The aim of the present study was to review the current literature relating to the impact
of dental implants on oral health-related quality of life (OHRQoL) in edentulous or partially dentate
patients.

Keywords: Systematic review; implants; quality of life; patient-reported outcomes

Data/Sources: Systematic literature searches were performed in the PubMed, EMBASE, and
Cochrane Library databases, using high level MeSH terms. The searches were limited to studies
published in English from 1960 to June 11, 2017, reporting OHRQoL outcomes using validated
instruments, and having enrolled at least 50 patients.

Study selection: After removal of duplicates, a total of 2,827 unique hits were identified. After title,
abstract, and full text screening, 63 articles were included in the review presenting findings of 55
individual studies. The provision of implant-supported dentures was associated with a significant
increase in OHRQoL in partially dentate and in edentulous patients, with the magnitude of achieved
improvement typically being greater for implant-supported dentures than with conventional ones.
Furthermore, OHRQoL impairment prior to treatment was strongly associated with OHRQoL
improvement.

Conclusion: For partially dentate patients, there is not enough evidence that implant-supported FDP
are superior in terms of OHRQoL than conventional FDP, but moderate evidence suggests that
implant-supported FDP perform better than conventional RDP. In edentulous patients, evidence
suggests that only if OHRQoL at baseline is highly impaired and patients request implant treatment,
IOD are superior than CD in terms of treatment-induced OHRQoL improvement.

1
Clinical significance: Patients can be informed that implant treatment is usually related to a
significant improvement in OHRQoL. However, improvement is not necessarily higher than for
conventional prosthodontic treatments but depends on patient’s clinical and psychosocial
characteristics.

2
 1 Introduction
Missing teeth are a common problem among adults of all ages, with the annual incidence of subjects
losing ≥1 teeth ranging from 1–14% in European countries.1 The prevalence of edentulism typically
increases with age; it is therefore a common problem especially in the elderly.1 In the US alone, it is
estimated that approximately one-third of adults aged ≥65 years are edentulous.2 Additionally, on a
global level, by 2020 an estimated 38 million adults will require one or two complete dentures.3
Tooth loss, and in particular visible tooth loss (i.e., in the aesthetic zone), is associated with aesthetic
problems and reductions in oral health-related quality of life (OHRQoL).4 Masticatory ability is also
influenced by tooth loss.5 The magnitude of impairment in OHRQoL is related to the number of
missing teeth, with studies showing an association between number of missing teeth and reduction
in OHRQoL.6,7 Additionally, subjects may be emotionally affected by tooth loss; a Hong Kong-based
study reported that tooth loss had a negative effect in terms of food choices, eating in public and
forming close relationships.8

A number of treatment options exist for subjects with missing teeth and also for those
completely edentulous, including the replacement of a single missing tooth using conventional and
implant-supported fixed dental prostheses (FDP) and for partially dentate (also referred to as
partially edentulous) or edentulous patients using conventional removable dental prostheses (RDP)
or implant-supported overdentures. However, some patients with conventional dentures,
particularly wearers of mandibular dentures, may experience looseness or mobility of the denture,
differences in salivary flow, oral sensory function and bite force, and an accelerated rate of residual
bone resorption.2 Some patients also experience aesthetic as well as functional problems including
difficulties in pronouncing certain sounds and chewing problems. Similarly, implants are associated
with caveats including higher initial costs and their placement is a more protracted process and
involves surgery, both of which may represent barriers for many patients.9-11 However, when it
comes to the question what treatment should be chosen, a conventional or an implant-supported
prosthesis, the patient perspective is a significant factor in decision-making, with OHRQoL
improvement to be expected following implant treatment being a highly relevant information.

While findings from single studies might vary or be even contradictory, systematic reviews offer the
best way to bring available information together. They allow to rate the methodological quality and
potential bias of the single studies and offer a critically condensed summary. Regarding the impact
of implant-supported prostheses on OHRQoL, systematic reviews are available for partially dentate
and edentulous populations.12-15 A systematic review by Thomason et al. included studies on
OHRQoL and patient satisfaction published 1996–2006 in a broad range of subjects including those
undergoing single tooth replacement as well as subjects who required reconstruction of the whole
jaw.12 The consensus findings were that subjects were more satisfied with implants than
conventional dentures and that OHRQoL is significantly improved following the placement of
implants. Another systematic review by Strassburger et al. on studies in partially dentate or
edentulous subjects published 1960–2003, concluded that the placement of implant-supported
mandibular prostheses is associated with an improvement in OHRQoL, but that the placement of
more than two implants does not result in further incremental improvements on OHRQoL or patient
satisfaction.13,14 Additionally, a 2009 systematic review by Emami et al. analyzed findings from
randomized controlled trials of mandibular implant-retained overdentures versus conventional
mandibular dentures in edentulous patients.15 While the meta-analysis of patient satisfaction
showed a large effect size in favor of implants, the effect in the meta-analysis of OHRQoL did not
achieve statistical significance and significant heterogeneity was reported between the studies. Even

3
though these reviews provide some evidence for the impact of implant support of prostheses on
patient perceptions, the reviews are somewhat outdated and do not consider more recent research
findings.

The aim of the present study was to review the current literature relating to the impact of
dental implants on OHRQoL in edentulous or partially dentate patients, and in particular to compare
the relative impact of implant-based prostheses with that of conventional prostheses in terms of
OHRQoL.

2 Materials and methods

The study was designed following the Preferred Reporting Items for Systematic Reviews and Meta-
Analyses (PRISMA) statement.16

2.1 Criteria for considering studies for this review

2.1.1 Type of studies

No exclusion criteria in terms of study design were applied; as such cross-sectional, retrospective,
and prospective studies were included. Studies could be either observational or randomized
controlled trials (RCT).

2.1.2 Types of participants

We considered adult male and female subjects for inclusion. Studies that were performed
exclusively in pediatric populations were excluded. At least 50 patients had to be enrolled in the
studies for inclusion.

2.1.3 Types of interventions

We included any study where at least a subgroup of participants had or received dental implants.

2.1.4 Types of outcome measures

For inclusion, studies were required to report OHRQoL outcomes using validated instruments such
as (but not limited to) the Oral Health Impact Profile (OHIP),17 the Geriatric Oral Health Assessment
Index (GOHAI),18 the UK oral health related quality of life measure (OHQoL-UK),19 or Dental Impact
on Daily Living (DIDL)20 questionnaires.

2.1 Search strategy

Literature searches were performed using the PubMed, EMBASE, and Cochrane Library databases,
together covering most of the scientific literature in the field. The initial search strategy was
designed for use in the PubMed database using high level MeSH terms as follows and adapted for
use in the EMBASE and Cochrane Library databases: ((((“Dental Prosthesis”[Mesh] OR “Dental
Restoration, Temporary”[Mesh] OR “Dental Restoration, Permanent”[Mesh] OR “Dental
Implantation”[Mesh] OR “Dental Implants”[Mesh] OR “Mandibular Prosthesis Implantation”[Mesh]
OR “Periodontium”[Mesh] OR “Prosthodontics”[Mesh]))) AND (“Quality of life”[Mesh] OR “patient
satisfaction” [Mesh])) NOT (Editorial[Publication Type] OR Letter[Publication Type] OR Case
Reports[Publication Type] OR Comment[Publication Type] OR Review[Publication Type]). The
searches were limited to studies published in English from 1960 to June 11, 2017.

4
 2.2 Data collection and analysis

2.2.1 Selection of studies

Title and abstracts were screened by one review author (RL), while full texts of articles were
assessed for inclusion independently by two review author (RL, JS). Disagreement was solved by
discussion.

2.2.2 Data extraction and management

A pair of review authors independently extracted data using a standardised data collection sheet.
The review authors were not blinded to authors of included studies. The two review authors
resolved disagreements by discussion or, if necessary, by consulting a third review author (DRR) in
order to reach consensus. The following information was recorded where available:

1. Year of publication, authors, and country of origin

2. Primary aim
3. Study design
4. Participants: sample size, age, gender, subgroups
5. Intervention: materials and techniques used, time to follow-up
6. Control: materials and techniques used, time to follow-up
7. Outcomes: primary and secondary outcomes

2.2.3 Assessment of risk of bias in included studies

Risk of bias assessment was performed for included studies with highest level of evidence, i.e., RTCs.
It followed the guidance in the Cochrane Handbook for Systematic Reviews of Interventions.21 Two
review authors (RL, JS) independently assessed and scored studies in order to identify any potential
sources of systematic. Judgements concerning the related risk of bias for each domain were assigned
as either ’low risk’, ’high risk’, or where insufficient information was available to make a judgement,
’unclear risk’. Additional a ’Risk of bias’ table for included studies is presented.

2.2.4 Data synthesis

Due to methodological differences, e.g. different OHRQoL questionnaires or versions, and different
characteristics in included studies resulting in substantial heterogeneity a meta-analysis was deemed
not indicated. Instead, for better comparison of study findings, standardizes effects sizes (ES) were
computed for differences and change scores. These ES allow not only to compare findings of studies
with different outcome measures, but also to assess the clinical relevance of the findings. According
to guidelines, an ES of 0.2 is considered small, 0.5 is medium, and 0.8 is “large”.22 Furthermore, an ES
of 0.5 represents the minimal important difference for many patients reported outcome measures.23

5
 3 Results

3.1 Description of studies

After removal of duplicates a total of 2,827 unique hits were identified. A first-round screen of all
titles and abstracts resulted in a short-list of 166 articles for full text review. Following this, a total of
63 articles presenting findings of 55 individual studies were selected for inclusion in the final review
(Figure 1).

A total of 21 studies were conducted in partially dentate subjects24-42 and two further studies
included a mix of edentulous and partially dentate subjects43-45 (Table 1). Furthermore, 32 studies
identified in the literature review were conducted in edentulous patients46-84 (Table 2).

3.2 Risk of bias of included RCTs

No included RCT showed overall risk of bias (Figure 2). Seven studies had a high risk of
bias.42,48,50,57,63,64,68,71,75 The other four studies were at unclear risk of bias.53,56,69,74,84

3.3 Findings for partially dentate subjects

3.3.1 Cross-sectional assessments

Four cross-sectional studies without a sufficient control group consistently reported low OHRQoL
impairment in partially dentate subjects treated with implant-supported fixed dental prostheses
(FDP).38,39,85,86

Another two cross-sectional studies with control groups were identified for partially dentate
subjects. These studies revealed that subjects with implant-supported FDP had substantially better
OHRQoL compared to subjects with conventional RDP (ES: 0.83),28 but not when compared to
subjects with conventional FDP for tooth replacement (ES: 0.38).40

3.3.2 Prospective treatment assessments

Several prospective studies assessed the effect of implant treatment on patients’ perceptions.
Among them, eighth studies demonstrated that after treatments with implant-supported FDP
OHRQoL improved significantly.26,30,32,35,36,41,42,45 Effect sizes for the impact of the new implant-
supported FDP on OHRQoL ranged in the studies from 0.49 in patients with short implants in the
posterior region42 to 1.2645 and 2.3835 in patients with missing anterior teeth. However, no other
treatment options were considered that would allow to compare the specific impact of the implants
with conventional dentures to replace missing teeth.

Further four studies were identified that compared the effect of implant-supported FDP to either
conventional FDP or RDP,25,29,33,34 with the majority observing higher OHRQoL improvement in
patients with implant treatment. While treatment with conventional FDP or RDP had no significant
short-term effect on OHRQoL in one study (ES: 0.07 and 0.10, respectively), implant-supported FDP
substantially improved OHRQoL (ES: 0.43).25 Furthermore, patients who received implants also
reported better chewing function (assessed using the Chewing Function Questionnaire; CFQ87) and
esthetics (assessed using the Orofacial Esthetic Scale, OES88), with the latter effect especially
pronounced in the FDP treatment groups.33 The specific impact of implant-support has also been
investigated up to 3 years post treatment with significantly higher treatment effects in patients with

6
implant-supported FDP (ES: 3.30) than in patients with conventional FDP (1.62).29 In contrast, one
study reported no significant difference in OHRQoL improvement between implant-supported and
conventional FDPs.34 However, none of the studies randomly allocated the treatment options to the
patients, limiting comparability of treatment effects.

3.3.3 Impacts on treatment effects

Ten studies were identified that explicitly assessed the impact of patient characteristics such as
personality traits,24 oral status such as number43,44 and location27 of missing teeth that require
replacement, or treatment characteristics such as loading protocol,31 implant diameter,85 implant
length,42 type of retention,86 or condition of the implant site41 on patients’ perceptions of effects of
implant treatment (Table 3).

Personality traits (neuroticism, extroversion, openness, agreeableness and conscientiousness;

assessed using the NEO-FFI89) significantly influenced the response to implant treatment, in
particular neuroticism, which was significantly correlated with implant treatment-induced
improvement in OHRQoL.24,36,37 That is, patients with higher levels of neuroticism perceived less
satisfactory effects of implant treatment.

All of the investigated clinical characteristics affected the treatment effects of dental implants.
Improvements in OHRQoL were significantly and positively related to the number of front teeth that
were initially missing and replaced by implants.43,44 Furthermore, subjects with tooth loss in the
anterior region showed the greatest improvement in OHRQoL following replacement (ES: 1.62)
compared to subjects with tooth loss in the molar area (ES: 0.47).27

In contrast, only some treatment characteristics were a significant predictor for differences in
treatment effect. One study provided evidence for the effect of the loading protocol on OHRQoL
improvement following treatment.31 Patients with immediately loaded implants had on average
higher change scores, i.e., more OHRQoL improvement (ES: 2.94) than patients with conventional
loaded implants (ES: 0.84). However, other treatment characteristics such as implant diameter
(3.3 mm vs 4.1/4.8 mm), implant length (6 mm vs. 11–15 mm), type of retention (cemented vs.
screwed), or condition of the implant site (extraction sockets vs. healed alveolar ridges) were not
associated with the size of the treatment effect.41,42,85,86

3.4 Findings for edentulous subjects

The majority of studies included here compared mandibular implant-supported overdentures (IOD)
versus conventional complete dentures (CD) in terms of OHRQoL.46-50,52,53,55-64,67-69,73-77,82 As such, only
one study was identified that assessed OHRQoL changes due to maxillary implant-supported
overdentures,54 and three studies that did not differentiate between implant support in the
mandible or the maxilla.51,65,66

3.4.1 Cross-sectional assessments

Six studies were identified with only a single assessment, thus just comparing different patient
populations.51,62,65,66,77,82,83 Patients with implant-supported FDP reported slightly better OHRQoL and
higher satisfaction than IOD patients, even though differences were statistically significant only in
the OHIP-14 domains psychologic discomfort and psychologic disability.51 Another study did not
report any significant difference in OHRQoL between patients with implant-supported FDP and
IOD.65 When comparing IOD with CD, findings were inconsistent. Satisfaction was significantly higher
in the implant group but no significant between-group differences were observed for OHRQoL.62,66 In

7
contrast, other studies reported significantly better OHRQoL in patients with IOD than with CD.77,82
Furthermore, patients with mini dental implants had OHRQoL comparable to conventional implant
support.83

3.4.2 Prospective treatment assessments

Of prospective studies to assess treatment effects, five were identified covering follow-up periods
between three months to five years that did not include a sufficient control group.46,49,54,55,67,76
Studies consistently reported OHRQoL improvement in edentulous patients after treatment with a
mandibular overdenture. Short-term impact (three to six months post treatment) of implant support
on OHRQoL ranged in these studies for two-implant OD from ES: 0.9867 to ES 2.32,55 and was ES: 1.47
for three-implant OD 76. Long-term effects (five years post treatment) were established in another
study with patients treated with mandibular overdenture supported by four immediately loaded
implants with OHRQoL and patient satisfaction (ES: 2.66) still improved at follow-up compared to
baseline.46,49

Further four studies included control groups but did not randomly assign treatment options to the
patients.47,61,73,75 Overall, most study showed superiority of IOD over CD in terms of OHRQoL
improvement.47,61,73 Treatment effects of IOD (ES: 1.18 and 7.62, respectively) were significantly
larger than of CD (ES: 0.46 and 3.52, respectively).47,75

Additionally, of the studies that compared IOD with CD a total of six RCTs have been identified with
five reported significant post-treatment between-group differences in favor of
implants50,56,57,63,64,68,74 Two to three months after treatment, impact of CD on OHRQoL (ES: 0.24 and
0.28, respectively) was consistently lower than impact of IOD (ES: 1.05 and 0.90, respectively).57,74 In
contrast, in one study there were no significant post-treatment differences at 3 months follow-up
between the patients receiving CD or patients receiving IOD.48 When longer follow-up periods are
considered, previous findings regrading a significant impact of implant support on OHRQoL were
confirmed. Patients with IOD had higher treatment effects six months (ES: 1.12 vs. 0.40), twelve
months (ES: 1.73 vs. 0.46), and two years (ES: 1.67 vs. 0.03) after treatment than patients with
CD.56,63,68

One study included in the present review were conducted exclusively in subjects with head and neck
cancer who subsequently required prosthetic dental restorations. The authors noted that the
placement of IOD was associated with improvements in most OHIP domains and improvements
were notably better in patients who had not undergone radiation treatment in comparison with
those who had.58,59 An indeed, while in irradiated patents effects were negligible or even adverse
indicated by negative effect sizes, non-irradiated patients perceived substantially higher
improvements at 6 months (ES: -0.17 vs. 0.35), 12 months (ES: -0.09 vs. 0.69), and 5 years (ES: 0.22
vs. 0.65) after treatment.

3.4.3 Impacts on treatment effects

Additional nine studies were included in this review that investigated the impact of several factors
such as atrophy of the maxilla and implant position,70,80,81 implant dimension,71 guided surgery,84
number of implants,78,79 retention system,72,78,79 dietary advices,52 sense of coherence (SOC),53,69 and
personality traits60 on treatment effects in terms of OHRQoL and satisfaction (Table 3).

Studies revealed a significant association between several treatment characteristics and OHRQoL
improvement, even though findings are not consistent. Number of implants and attachment type
were associated with OHRQoL with lowest OHIP summary scores observed in patients with 4-

8
implant-supported bars and highest scores in patients with two implants and balls.78,79 Similar
findings with respect to OHRQoL were observed on another study.72 Three to five years after
provision with new IOD, OHRQoL was highest in patients with 4 mini-implants with ball ring
matrices, followed by patients with 2 standard implants with locator, and worst in patients with 2
implants with bar-retained IOD. Furthermore, OHRQoL improvement was higher in patients
receiving 2 or 4 mini-implants than in patients with 2 standard implants for the support of
mandibular IOD.71 However, better results in terms of OHRQoL and satisfaction in patients with mini-
implants than in patients with standard implants were associated with considerably lower implant
survival rates at 12-months follow-up (4 mini-implants: 89%, 2 mini-implants 82%, and 2 standard
implants: 99%). Longer interimplant distance between two implants in the edentulous mandible also
positively affected treatment-induced OHRQol improvements 80,81. In contrast, guided surgery or
implant position in the maxilla (palatal positioned implants in severely atrophic maxillae vs. well-
centered placed implants in the non-atrophic maxilla) had no impact on OHRQoL.70,84

Customized dietary advice had no meaningful effect on OHRQoL in edentulous patients with CD or
IOD.52 Furthermore, SOC was not associated with OHRQoL.53,69 However, OHRQoL was related to
personality traits with neuroticism being the most relevant one.60 That is, patients who expressed
more neuroticism had on average worse OHRQoL.

4 Discussion
The review revealed that there is a substantial number of studies investigating the effect of implant
placement on OHRQoL, with the majority of studies performed in edentulous patients. Analysis of
the studies included in the present review shows that the provision of implant-supported dentures is
associated with a significant increase in OHRQoL in partially dentate and in edentulous patients, with
the magnitude of achieved improvement typically being greater for implant-supported dentures
than with conventional ones.

However, these findings have to be interpreted with caution. In partially dentate patients, the
consensus finding among OHRQoL studies is that treatment with implant-supported FDP improves
OHRQoL. But this is not surprising since obviously these patients had a demand for prosthodontic
treatment. Accordingly, pre-treatment OHRQoL might have been substantially impaired due to tooth
gaps or provisional prostheses, and it is well known that the provision of new definitive prostheses
has a positive and long-lasting effect on OHRQoL.90 Therefore, the effects of implant-supported FDP
on OHRQoL might be related to the prosthodontic replacement of missing teeth rather than a
specific impact of the implants. When compared to conventional RDP, implant-supported FDP were
associated with better OHRQoL and greater treatment-induced improvements. As a matter of fact,
patients with FDP have better OHRQoL than those with RPD, irrespective of implant support.91
Furthermore, both groups are not well comparable since treatments in studies with partially dentate
patients were not randomly assigned but based on dental status and patient request. Typically,
implant patients have higher levels of education and income.60 For patients with lower socio-
economic status (SES), financial constraints may be barriers to the placement of implants. But
simultaneously, OHRQoL is related to SES with a lower magnitude in subjects with lower SES.
Interestingly, when comparing treatments with implant-supported and conventional FPD, both
significantly improved OHRQoL with no significant difference in the magnitude.34 Therefore, there is
no evidence so far for partially dentate patients that implant-supported FDP are superior in terms of
patient perceptions than conventional FDP, but moderate evidence suggests that implant-supported
FDP perform better than conventional RDP.

9
Studies in edentulous patients indicate that treatment with IOD improves OHRQoL, and
improvement is slightly higher than for conventional CD. However, this finding was not consistently
observed in all studies, and cross-sectional comparisons revealed no significant difference between
subjects with IOD or CD. One possible reason might be that patients requesting implant treatment
typically experienced more problems related to their oral health.47 Accordingly, the potential
improvement is greater than in patients with initially less impaired OHRQoL, what was actually
observed in the studies. Not surprising, in patients who are satisfied with their current conventional
dentures, implant placement does not add a substantial amount of satisfaction.92 Even in most of
the identified RCTs study participants are not well representative for all edentulous subjects since
they were recruited based on the consent for implant treatment, i.e., the majority of participants
had a request for implant treatment, what is very likely related to substantially impaired OHRQoL.
Accordingly, the effects if implants on OHRQoL are greater in patients who request implants than in
those who do not. Interestingly, the study by Allen and McMillan showed that even though OHRQoL
improvement was greater in patients who requested and received IOD than in those who requested
and received CD, post-treatment impairment was still substantially lower in the CD group than in the
IOD group.47 Another study showed that if all study participants believe that they would receive
conventional dentures, no significant differences between IOD and CD treatment was observed.48 All
these findings from studies in edentulous patients suggest, that only if OHRQoL is highly impaired
and patients request implant treatment IOD are superior than CD in terms of treatment-induced
OHRQoL improvement. After treatment, subjects satisfied with their CD or with their IOD do not
necessarily differ in perceived problems related to their oral health. That might also be an
explanation while most RCTs did not report follow-up results for longer periods, what would be an
indicator for publication bias.

The findings of studies included in the current review also suggest that personality traits, especially
neuroticism, and treatment characteristics such as number and location of replaced teeth are
related to OHRQoL and response to treatment. Subjects with high levels of neuroticism tend to be in
a negative emotional state, i.e., they have feelings of guilt, envy, anger, anxiety, and depressed
mood more frequently and severely than others.93 It is therefore not surprising that patients who
express more neuroticism have on average worse OHRQoL, especially since psychosocial impact is
one of the four dimensions of OHRQoL.94,95 Accordingly, high levels of neuroticism can be considered
a risk factor for treatment failures, at least for the patient perspective. For partially dentate subjects,
the magnitude of OHRQoL improvement after treatment is linked to the number and location of
implants to replace missing teeth,27,43,44 with higher improvements for anterior than posterior tooth
loss and more teeth replaced. This is not surprising given the positive correlation between number
of teeth and OHRQoL and more severely impaired OHRQoL due to anterior than posterior tooth
loss.4 Furthermore, effects of location of prosthodontic treatments on OHRQoL improvements are
also well known.96 Least treatment effects can be expected for the replacement of missing molars.27
This is obviously related to a low impact of missing molars on OHRQoL, what is represented in the
proportion of patients with treatment demand. In a large multicenter study in Japan, only 3% of
subjects sought treatment for missing second molars.97 When first and second molars were missing,
a condition described as a shortened dental arch (SDA),98 only slightly more than half of the subjects
requested prosthodontic replacement of missing teeth. Even though loss of molars is related to
OHRQoL impairment, especially in the domain oral functions such as chewing,99 extend of
impairment is low compared to effects of missing anterior teeth. Accordingly, for implant-supported
FDP to replace missing molars, a treatment effect that can be perceived by the patients can only be
expected if OHRQoL was substantially impaired before treatment.

10
The findings of the current review are in accordance with previous reviews on this topic, even
though number of included studies differed. Thomason et al. identified 74 studies,12 Strassburger et
al. 114 studies,13,14 and Emami et al. 10 studies,15 while in the current review 55 studies were
included. These differences are in part due to different periods covered by the review or inclusion
criteria (e.g., the review by Emami et al.15 analyzed only RTCs of mandibular IOD and CD in
edentulous patients). Furthermore, studies had to have at least 50 subjects enrolled to be included
in the current review. The consensus findings of these previously conducted reviews were that
subjects were more satisfied with implant-supported than with conventional dentures and that
OHRQoL is significantly improved following the placement of implants.12-15 This is in accordance with
the findings of the current review. However, important aspects regarding effects of implants on
OHRQoL are hardly addressed if that, i.e., the prerequisite of substantial OHRQoL impairment before
treatment, the requirement of request for implants, and the effect of number and location of
implants in partially dentate patients. Therefore, the current review adds important information to
the available knowledge on impact of implants on OHRQoL.

The period for the search covered 57 years, starting with studies published in 1960. The current
review was focused exclusively on studies reporting OHRQoL using validated measures including the
full and abbreviated forms of the OHIP, GOHAI, and DIDL. Patient satisfaction and OHRQoL are
frequently used synonymously; however, studies reporting patient satisfaction only were not
included in the current review as many of these report results only in a qualitative rather than
quantitative manner. During the literature review process, it was apparent that a large number of
patient satisfaction studies have been published but that substantial heterogeneity exists in terms of
the outcome measures used to assess patient satisfaction. The use of a large number of different
methods of outcomes assessment measures complicates the comparison of results across different
studies. Consequently, the remit of the current literature review was limited to studies reporting
OHRQoL using validated outcome measures. However, instruments for general HQoL, such as the SF-
36100 or the EQ-5D101 often fail to capture subtle changes in QoL associated with a particular oral
condition.102,103 In contrast, the OHIP is the most frequently used instrument for assessment of
OHRQoL that has the potential to become the standard method,104 ensuring the conduction of
methodologically high-quality studies and comparison of findings across these studies. There is also
another factor that should be taken into account when interpreting the findings of the studies
included in the current review. In the majority of prospective studies, OHRQoL was assessed prior to
treatment and post-treatment, with the typical post-treatment assessment made within 12 months
of implant placement. A key limitation of using short time frames is that such studies will not
capture OHRQoL detriments associated with late implant failures or late complications such as peri-
implantitis. Furthermore, it is somewhat suspect when elaborate RCTs have only short follow-ups,
and data on long-term effects are lacking. One could assume that at later follow-ups difference
between treatment options were no longer present and, therefore, findings were not reported. Such
form of publication bias is not rare; studies with statistically significant results are more likely to be
published than those with no difference between groups.105

In summary, the results of OHRQoL studies suggest that both implant-supported prostheses and
conventional dentures are associated with improvements in OHRQoL, with OHRQoL impairment
prior to treatment being strongly associated with OHRQoL improvement to be expected. Currently,
there is not enough evidence that implant-supported FDP are superior in terms of OHRQoL than
conventional FDP in partially dentate patients, but moderate evidence suggests that implant-
supported FDP perform better than conventional RDP. In edentulous patients, evidence suggests
that only if OHRQoL at baseline is highly impaired and patients request implant treatment, IOD are
superior than CD in terms of treatment-induced OHRQoL improvement.

11
 Tables
CFQ, Chewing Function Questionnaire; DIDL, Dental Impact on Daily Living; EuroQoL, European Quality of Life indicator; GOHAI, Geriatric Oral Health Assessment Index; NEO-FFI, Neuroticism Extraversion Openness
Five-Factor Inventory; OES, Orofacial Esthetic Scale; OHIP, Oral Health Impact Profile; OHRQoL, oral health-related quality of life; QoLIP, Quality of Life with Implant-Prostheses; VAS, Visual Analogue Scale

12
BACQ, Brief Approach/Avoidance Coping Questionnaire; DIDL, Dental Impact on Daily Living; DSQ, Dental/Denture Satisfaction Questionnaire; EORTC, European Organization for Research and Treatment of Cancer;
ITT, intention to treat; NEO-FFI, Neuroticism Extraversion Openness Five-Factor Inventory; OHRQoL, oral health-related quality of life; PRO, Patient-Reported Outcome; QoLIP, Quality of Life with Implant-Prostheses;
RCT, randomized controlled trial; SEIQoL, Schedule for the Evaluation of Individual Quality of Life; SIQ, Social Impact Questionnaire; SOC, Sense of Coherence; VAS, Visual Analogue Scale

13
14
Figure 1 – Schematic diagram of literature search and screening process

15
Acknowledgements
This study was in part supported by funding from Straumann AG. The funder had no role in study
design, data collection and analysis, decision to publish, or preparation of the manuscript.

Figure 2 – Risk of bias summary: review authors’ judgements about each risk of bias item for each
included RCT

16
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Figures
Articles retrieved from searches
(N=3,900)
EMBASE (n=1,462)
PubMed (n=2,037)
Cochrane (n=401)

Duplicates removed (n=1073)

Unique articles for title and abstract

review
(n=2,827)

Articles excluded (n=2661)

Articles included for full text review

(n=166)

Articles excluded (n=103)

Non-eligible population (n=8)
Non-eligible outcome (n=86)
Articles included in final review Non-eligible intervention (n=5)
(n=63) Fulltext unavailable (n=4)

24
Table 1 – Summary of OHRQoL studies on implant-supported prostheses in partially dentate subjects

Study (year) Aim Methods and design Subjects Summary findings

Abu Hantash To investigate the Prospective, clinical study N=50 patients Personality traits influenced
et al. 200624 impact of psychological Assessments: before Mean age: 43.2 yrs patients’ responses to
characteristics on treatment and 2–3 (range: 22–71 yrs) implants; neuroticism was
OHRQoL in patients months after treatment significantly linked to overall
receiving implant- 44.0% female satisfaction (lower levels of
supported single crowns Measures: OHRQoL and neuroticism associated with
or fixed partial dentures personality traits higher levels of satisfaction).
Instruments: DIDL, NEO-
FFI

Al-Omiri et. Comparison between Prospective, clinical study N=80 patients Patients’ satisfaction with
al. 201136 satisfaction with the Assessment: before Mean age: 41.0 yrs their dentition was higher
dentition and dental treatment and 3 months (range: 18-77 yrs) after implant treatment.
prostheses and after rehabilitation Patients’ daily living and
personal profiles in 47.5% female satisfaction with implant-
patients with implant- Measures: patient supported prostheses were
supported prostheses satisfaction, personality affected by personality traits.
traits
Instruments: DIDL, NEO-
FFI

Al-Omiri et. Assessment of the Cross-sectional study N=100 patients (implant Satisfaction was higher in
al. 201237 relationship between Assessment: > 3 month patients: n=50; partially patients with implants than in
satisfaction with implant- after treatment dentate controls: n=50) the control group. Daily living
supported fixed Mean age = 44.3 yrs and satisfaction of patients
rehabilitations, their Measures: dental with implant-supported fixed
satisfaction (range = 23–60 yrs)
impacts on daily living, prostheses were influenced
and personality profiles Instruments: DIDL, NEO- 70% female by personality traits.
FFI

Alzarea et. To investigate OHRQoL Cross-sectional study N=92 patients Patients with dental implants
al. 201638 of patients with dental Assessment: 1 year after Mean age: 43 yrs (range were satisfied with their
implants and periodontal treatment 25-68 yrs) OHRQoL.
parameters of implants
and healthy teeth Measures: OHRQoL 47.8% female
Instruments: OHIP-14

Bramanti et To determine the impact Prospective, clinical study N=50 patients OHRQoL improved after
al. 201330 of implant-supported Assessments: before Mean age: 51.2 yrs treatment with implant-
fixed partial dentures supported fixed partial
treatment and 2 years (range: 40-70 yrs)
rehabilitation on dentures, especially in
after treatment 56% female
OHRQoL among patients with Kennedy class I
partially edentulous Measures: OHRQoL and IV.
patients. Instruments: OHIP-14

Dolz et al. To compare the effect of Prospective, non- N=104 patients A significant improvement
201431 implant rehabilitation on randomized clinical trial (immediate loading was observed in OHRQoL
HRQoL and OHRQoL Assessments: before group: n=29; and global oral satisfaction
when implants are treatment, 3 months after conventional loading but not in HRQoL for both
loaded either implant placement, and group: n=75) loading groups from baseline
conventionally or to the final evaluation. The
3–5 months after final Mean age: 55.5 yrs
immediately improvement in OHRQoL
restoration (range: not provided)
was markedly greater in the
Measures: OHRQoL, 55.5% female patients who received
HRQoL, global oral immediately loaded implants.
satisfaction There were no significant
Instruments: OHIP-49, differences in the ratings of
EuroQoL, VAS general oral satisfaction or
HRQoL.

25
Study (year) Aim Methods and design Subjects Summary findings
Fillion et al. Assessment of Prospective, clinical study N=176 patients (single Implant treatment improved
201332 OHRQoL improvement Assessments: before and tooth group: n=77; fixed OHRQoL of participants.
in patients who 3–15 months after implant partial denture group: Before treatment, the mean
underwent dental n=75; full prostheses GOHAI scores were lower
placement
implant treatment group: n=24) for participants with fewer
Measures: OHRQoL teeth. Highest improvement
Mean age: 52.0 yrs
Instruments: GOHAI (range: 18-84 yrs) was observed in patients
who needed complete
59.1% female dentures.

Furuyama et Comparison of OHRQoL Cross-sectional study N=188 patients (implant- Mean OHIP summary
al. 201228 in subjects with at least Assessments: once at supported fixed dentures domain scores were
one dental implant and [ID] group: n=79; significantly higher in
least 1 month’s usage of
with removable partial removable partial subjects with removable
either treatment
dentures dentures [RPD] group: partial dentures than in
Measures: OHRQoL n=109) subjects with implant-
Instruments: OHIP-49 Mean age: 51.7 yrs [ID] supported fixed dentures,
and 66.5 yrs [RPD] corresponding to better
OHRQoL in the latter group.
(range: not provided)
55.7% [ID] and 69.7%
[RPD] female

Goiato et al. Evaluation of OHRQoL Cross-sectional study N=106 patients The OHRQoL of patients
201539 of patients with implant- wearing implant-supported
Assessments: once Mean age: 54.2 yrs
supported fixed partial fixed partial dentures was
Measures: OHRQoL (range: not provided)
dentures. high.
Instruments: OHIP-14 58.5 % female

Herrmann et Comparison of implant Retrospective study N=311 patients There was no significant
al. 201685 survival and OHRQoL of (reduced-diameter difference in patients’
Assessments:
reduced-diameter posttreatment (mean implants [test] group: OHRQoL between those
implants and regular- follow-up period: 22.4 ± n=107; regular-diameter with reduced-diameter
diameter implants 8.2 months) implants [control] group: implants or regular-diameter
n=204) implants.
Measures: OHRQoL
Mean age: 53.3 yrs [test
Instruments: OHIP-14 group] and 60.2 yrs
[control group] (range:
not reported)
57.9% [test group] and
54.8% [control group]
female

Kimura et al. Assessment of Prospective, clinical study N=138 patients (implant- A significant response shift
201225 response shift in Assessment: before supported fixed dentures was reported in subjects with
OHRQoL measures in treatment and after [ID] group: n=78; implant-supported fixed
subjects receiving conventional fixed partial partial dentures and fixed
treatment completion
implant-supported fixed dentures [FPD] group: partial dentures but not for
or removable partial Measures: OHRQoL n=37; removable partial those with removable partial
dentures Instruments: OHRQoL dentures [RPD] group: dentures. Only subjects with
questionnaire by n=23) implant-supported fixed
Sonoyama et al.106 Mean age: 61.4 yrs partial dentures had a
(range: 24–87 yrs) significant improvement in
OHRQoL, irrespective
73.2% female whether response shift was
taken into account.

26
Study (year) Aim Methods and design Subjects Summary findings
Kriz et Assessment of Prospective, clinical study N=97 patients Implant treatment was
al.201244 and OHRQoL improvement Assessment: before Mean age: 46.9 yrs associated with
Pavel et al. in patients receiving implantation and at least (range: not provided) improvements in OHRQoL,
201243 implant-supported fixed, which was influenced by the
1 month after 58.8% female
removable, or complete number of front teeth
prosthodontic
dentures rehabilitation replaced with higher
improvements when more
Measures: OHRQoL front teeth were replaced.
Instruments: OHRQoL
questionnaire based on
GOHAI and OHIP-14

Nickenig et Assessment of Prospective, clinical study N=343 patients (partially In the implant group, a
al. 200826 OHRQoL in partially edentulous implant significant improvement in
Assessments: before
edentulous subjects patients [IP]: n=219, fully OHIP score was reported
implantation and 1–2
before and after implant months after dentate controls [DC]: post-treatment, but OHRQoL
treatment prosthodontic n=124) after implant treatment was
rehabilitation Mean age: [IP] 44.7 yrs still slightly more impaired
(range 19.2–67.6 yrs) than in fully dentate controls.
Measures: OHRQoL
and [DC] 45.2 yrs (range
Instruments: OHIP-21 21.3–56.7 yrs)
Gender: not provided

Nickenig et Assessment of the Prospective, multicenter N=8689 patients OHRQoL improved after
al. 201645 impact of dental clinical study treatment with dental
Mean age: 48.8 yrs
implants on OHRQoL. implants and prosthodontic
Assessments: (range: 19-89 years).
rehabilitation. The most
preoperative, 46,7% female
intermediate and significant improvement was
posttreatment observed in patients with
edentulous jaws or anterior
Measures: OHRQoL single-tooth gaps.
Instruments: OHIP-21

Park et al. Comparison of OHRQoL Cross-sectional study N=71 patients (single- After treatment, OHRQoL
201640 after treatment with Assessments: tooth implant group: was rated better than before
single-tooth implants n=35; three-unit FPD: treatment without significant
retrospective
versus three-unit fixed n=36) differences between groups.
pretreatment (then test)
partial dentures for and posttreatment Mean age: 52.2 yrs
single missing tooth (range: 40-69 yrs)
restoration. Measures: OHRQoL
Instruments: OHIP-14 69% female

Perea et al. Assessment of Cross-sectional study N=84 patients (screwed The highest improvement in
201586 OHRQoL of cemented Assessments: once after FDPs supported by 2 QoL was assessed for short
implant prostheses for 1 year of treatment implants: n = 35); cemented implant
validation of the QoLIP- screwed FDPs restorations. Patient
10 questionnaire Measures: OHRQoL supported by 3–5 satisfaction depended on
Instruments: OHIP-14, implant: n=7; cemented extension and type of
QoLIP-10 FDPs supported by 2 retention of the restoration.
implants: n=36;
cemented FDPs
supported by 3-5
implants: n=6)
Mean age: not provided
57.1% female

27
Study (year) Aim Methods and design Subjects Summary findings
Persic et al. Assessment of Prospective, clinical study N=263 patients After-treatment, OES,
201533 improvement in orofacial Assessments: before (conventional dentures OHIP14, and CFQ scores
esthetics, chewing treatment and 3 months group: n=151; implant- were significantly better than
function and OHRQoL supported dentures baseline scores for all types
after prosthodontic
on different group: n=112) of treatments. Implant
rehabilitation
prosthodontic Mean age: 62.3 yrs support resulted in
rehabilitation options Measures: OHRQoL, significantly higher
orofacial esthetics, (range 27–93 yrs)
improvements in OHRQoL,
chewing function 61.6% female orofacial esthetics, and
Instruments: OHIP-14, chewing function than for
OES, CFQ conventional dentures.

Petricevic et Assessment of Prospective, clinical study N=164 patients (implant-Baseline OHIP score were
al. 201229 OHRQoL in subjects supported fixed partial significantly higher (worse) in
Assessment: before
with implant- and tooth- dentures [ID] group: the implant group versus the
treatment and at 3 weeks
supported fixed partial and 3 years after n=64; tooth-supported fixed partial denture and the
dentures prosthodontic fixed partial dentures control group. OHRQoL was
rehabilitation [FPD] group: n=38; significantly improved 3
control group [CG]: weeks after prosthodontic
Measures: OHRQoL n=62) treatment in both treatment
Instruments: OHIP-49 groups, and further improved
Mean age: 46.5 yrs [ID],
57.6 yrs [FDP], and 42,3 to 3 years post treatment.
yrs [CG] (range 28–74 Even though decrease in
yrs) OHIP scores was higher in
patients with implant
43.8% [ID], 63.2% support, OHRQoL was still
[FPD], and 69.4% [CG] more impaired after
female treatment than in patients
with tooth-supported
dentures.

Ponsi et al. Comparison of changes Prospective, clinical study N=80 patients In the total population, mean
201127 in OHRQoL due to Assessment: after implant Mean age: 52 yrs OHIP score improved
placement of a single placement before (range: 24–75 yrs) significantly following
implant in different uncovering and 3 months treatment. However,
areas (anterior, 64% female OHRQoL improvement was
after prosthodontic
premolar, and molar only significant for replaced
rehabilitation
areas) anterior teeth or premolars
Measures: OHRQoL but not for molars.
Instruments: OHIP-14

Raes et al. Comparison of OHRQoL Case-control study N=96 patients OHRQoL improved in both
201241 of patients with single Assessment: at baseline (extraction group: n=46; treatment groups. There was
implants after placement and 1, 6, and 12 months healed ridge group: no significant difference in
in extraction sockets after treatment n=50) OHIP-scores between
with placement in groups.
Measures: OHRQoL Mean age: 43 yrs
healed alveolar ridges
(range: 18-72 yrs)
Instruments: OHIP-14
57.3% female

Swelem et Investigation of changes Prospective, clinical study N=200 patients (tooth- All treatments produced
al. 201434 in OHRQoL in partially supported fixed dental significant improvements in
Assessment: before
edentulous patients prostheses group: n=32; OHRQoL. Changes in OHIP
treatment and 6 weeks
after different types of removable dental summary scores were
and 6 months after
treatment with tooth- prosthodontic prostheses group: comparable in patients
supported and implant- rehabilitation n=111; implant- treated with either tooth-
supported dentures supported fixed dental supported or implant-
Measures: OHRQoL prostheses group: n=57) supported fixed dental
Instruments: OHIP-14 prostheses.
Mean age: 41.8 yrs
(range: 30–50 yrs)
50.0% female

28
 Study (year) Aim Methods and design Subjects Summary findings
Thoma et al. Comparison of OHRQoL Prospective, RCT N=101 patients The implant survival rate
201542 and implant survival rate Assessment: at baseline, Mean age: 50.5 yrs was 100%. OHIP summary
of short (6 mm) versus at suture removal, at (range: 20-75 yrs) scores decreased in both
long (11-15 mm) dental groups between baseline
prosthesis insertion, and 51.5 % female
implants in combination and follow-up.
at 1-year follow-up
with sinus grafting
Measures: OHRQoL,
implant survival
Instruments: OHIP-49

Yu et al. Investigation of the Prospective, clinical study N=238 patients In patients with partial
201335 relationship between Assessment: before Mean age: 41.5 yrs removable dentures for
anterior teeth implantation and at 6 (range: 29–56 yrs) anterior teeth loss who seek
implantation and replacement of these
months after 55.9% female
OHRQoL improvement dentures, treatment with
prosthodontic
rehabilitation implant-supported fixed
dental prostheses
Measures: OHRQoL, significantly improved
implant restoration- OHRQoL. Most patients
related satisfaction were satisfied with treatment
Instruments: OHIP-14, result.
satisfaction items

Table 2 – Summary of OHRQoL studies on implant-supported prostheses in edentulous subjects

Study (year) Aim Methods and design Subjects Summary findings

Attard et al. Assessment of clinical Prospective, clinical N=77 patients (n=35 One year after treatment, there
200649 and and patient-reported study patients with data on was a statistically significant
Alfadda et al. outcomes 5 years after PROs) improvement in total and
Assessment: before
200946 placement of treatment and at 1 and 5 Mean age: 64.1 yrs functional dental satisfaction
mandibular implant- years after prosthodontic (range: not reported) scores and in OHRQoL. Initial
supported rehabilitation improvements were
overdentures with 39.1% female maintained over five years.
immediate loading Measures: OHRQoL,
dental satisfaction
Instruments: OHIP-20,
DSQ

Allen et al. Assessment of the Prospective, clinical N=75 patients (implant Preoperative, satisfaction in
200173 impact of preoperative study denture [ID] group: the three groups was very low.
expectations and Assessment: before n=20; conventional At 3 months after treatment,
implant-stabilized treatment and 3 months denture group 1 [CD1]: the three groups had a higher
prostheses versus after prosthodontic n=20; conventional denture satisfaction and
conventional rehabilitation denture group 2 [CD2]: decreased OHIP summary
prostheses on oral n=35) scores. The expectation levels
health status Measures: OHIP, preoperative did not influence
denture satisfaction, Mean age: 55.8 yrs [ID],
60.2 yrs [CD1], and the satisfaction.
expectations of implant
therapy 65.1 yrs [CD2] (range:
not reported)
Instruments: OHIP-49,
DSQ 85.0% [ID], 55.0%
[CD1], and 74,3%
[CD2] female

29
Study (year) Aim Methods and design Subjects Summary findings
Allen et al. Assessment of implant- Prospective, RCT N=118 patients (implant At 3 months after treatment,
200648 retained overdentures Assessment: before denture [ID] group: there were significant
(2 implants) versus n=62; conventional improvements in OHRQoL and
treatment and at 3
conventional complete denture [CD] group: denture satisfaction in both
months after treatment
dentures reporting n=56) groups versus baseline.
clinical and OHRQoL Measures: OHRQoL, However, no significant
denture satisfaction Mean age: 64.5 yrs [ID]
outcomes and 68.5 yrs [CD] differences between treatment
Instruments: OHIP-49, (range: not reported) groups were observed.
DSQ
71.1% [ID] and 71.7%
[CD] female

Allen and Clinical trial of the Prospective, clinical trial N=103 patients (implant Subjects requesting implants
McMillan impact of oral implants Assessment: pre- and denture [ID] group: had lower baseline OHRQoL
200347 on OHRQoL n=26; conventional versus patients requesting
posttreatment
denture implant request conventional dentures. Effect
Measures: HRQoL, [CD1] group: n=22; size for change in OHIP score
OHRQoL, denture conventional denture was large for the group
satisfaction [CD2] group: n=35; receiving implants and small
Instruments: OHIP-49, dentate control [DG] for both groups receiving
DSQ, SF-36 group: n=20) conventional dentures.
Mean age: 58.7 yrs [ID
and DG], 60.2 yrs
[CD1], and 65.1 yrs
[CD2] (range: not
provided)
88.5% [ID], 54.5%
[CD1], 74.3% [CD2],
and 30.0% [DG] female

Awad et. al. Comparison of Prospective, RCT N=102 patients The assessment indicates that
200074 OHRQoL in patients Assessment: pre- and 2 (conventional denture patients with implants have a
with mandibular [CD] group: n=48; more positive OHRQoL
month posttreatment
implant-supported implant overdenture compared to conventional
overdentures and Measures: OHRQoL [IOD] group: n=54) therapy.
patients with Instruments: OHIP, VAL Mean age: not provided
conventional (range: 35-65 yrs)
prostheses
49% female

Awad et al. Comparison of patient Prospective, RCT N=60 patients At 2 months post treatment,
2003,50 satisfaction, OHRQoL, Assessment: before (conventional denture subjects who received
Heydecke et and HRQoL in elderly treatment and 2, 6, and [CD] group: n=30; implants had higher
al. 2003,68 and subjects receiving 12 months after implant overdenture satisfaction than subjects who
Heydecke et mandibular 2-implant [IOD] group: n=30) received conventional
treatment
al. 200556 supported dentures. Post-treatment OHIP
Measures: OHRQoL, Mean age: 69.4 yrs
overdentures or [CD] and 68.9 yrs [IOD] score was significantly better
conventional dentures dental satisfaction, in subjects receiving implants
HRQoL (range 65–75 yrs)
in comparison with those
Instruments: OHIP-49, 60.0% [CD] and 53.3% receiving conventional
VAS, SF-36 [IOD] female dentures. However, effects of
implant treatment on HRQoL
were only significant for
subscales Role Emotional,
Vitality, and Social Function.

30
Study (year) Aim Methods and design Subjects Summary findings
Awad et al. Comparison of Prospective, multicenter, N=203 patients (implant The proportion of patients who
201461 OHRQoL in subjects non-randomized denture [ID] group: showed improved OHIP-20
receiving 2-implant controlled trial n=104; conventional scores at 6 months was higher
supported mandibular denture [CD] group: in the groups receiving
Assessment: at baseline
overdentures and and 6 months after n=99) implants in comparison with
conventional dentures treatment Mean age: 68.8 yrs those receiving conventional
(range: not provided) dentures.
Measures: OHRQoL
Instruments: OHIP-20 61.4% [ID] and 57.4%
[CD| female

Brennan et al. Comparison of Cross-sectional study N=62 patients (implant- Overdenture group reported
201051 OHRQoL and patient Assessment: after supported overdenture lower overall satisfaction and
satisfaction in subjects treatment (no exact [IOD] group: n=25; satisfaction with chewing
receiving implant- implant-supported fixed ability and esthetics versus
follow-up time reported)
supported denture [IFD] group: subjects with fixed prostheses.
overdentures and Measures: OHRQoL, n=37) Overall OHRQoL was high in
implant-supported fixed satisfaction both groups; subjects in the
Mean age: 57.5 yrs
dentures Instruments: OHIP-14, [IOD] and 56.0 yrs [IFD] fixed prostheses group had
VAS (range: not provided) significantly lower levels of
psychological discomfort and
56.0% [IOD] and 67.6% psychological disability versus
[IFD] female overdenture subjects.

Candel-Marti Comparison of Cross-sectional study N=57 patients (palatal Satisfaction and quality of life
et al. 201570 OHRQoL and Assessment: 5-11 years positioned implants [PI] were high and similar in both
satisfaction in patients after implant treatment group: n=32; well- groups.
with palatal positioned centered implants [CI]
implants and with well- Measures: OHRQoL, group: n=25)
centered implants satisfaction
Mean age: 55.0 yrs [PI]
supporting fixed full- Instruments: OHIP-14, and 55.9 yrs [CI]
arch prostheses VAS (range: not provided)
75% [PI] and 48% [CI]
female

Cakir et. al. Comparison of Prospective, RCT N=116 patients OHRQoL improved in all
201475 satisfaction and QoL in (implant-retained groups at post-treatment.
Assessment: before
in subjects receiving treatment and 1 yr after overdentures n=29, Highest improvement was
mandibular complete treatment implant-supported observed in the implant-
dentures, implant- FPDs n=29, retained overdenture group.
retained overdentures, Measures: QoL conventional complete
removable partial Instruments: OHIP-14, dentures n=29, or RPD
dentures, or implant- OHQoL-UK, SF-36 n=29)
supported fixed partial Mean age: 58.0 yrs
dentures (range: 36-81 yrs)
54.3% female

De Souza et Comparison of Prospective, RCT N=120 patients (4 mini- OHRQoL and satisfaction
al. 201571 mandibular Assessment: before implants [4MI] group: improved in all groups post-
overdentures retained intervention and 3, 6 and n=38; 2 mini-implants treatment, with most favorable
by 2 or 4 mini-implants 12 months after [2MI] group: n=42; 2 results in patients with mini-
with standard implants treatment standard implants [2SI] implant-retained mandibular
group: n=40) overdentures. However, the
Measures: OHRQoL, provision of mini-implants was
satisfaction Mean age: 59.3 yrs
associated with considerably
[4MI], 59.1 yrs [2MI],
Instruments: OHIP- and 60.2 yrs [2SI] higher implant failure rate than
EDENT, VAS (range: not provided) observed for standard
implants.
68,4% [4MI], 71,4%
[2MI] and 62,5% [2SI]
female

31
Study (year) Aim Methods and design Subjects Summary findings
Ellis et al. To investigate the Prospective, clinical N=54 patients (implant- At 6 months, the implant group
201052 impact of dietary advice study supported overdenture had significantly better
in subjects with 2- [IOD] group: n=28; satisfaction scores in terms of
Assessment: before
implant-supported conventional denture denture comfort, stability and
intervention and 6
mandibular months after dietary [CD] group: n=26) chewing ability. However,
overdentures and advice was provided Mean age: 65.4 yrs there was no significant
conventional dentures [IOD] and 70.6 yrs [CD] between-group difference in
Measures: OHRQoL, OHRQoL.
(range: not provided)
satisfaction
Instruments: OHIP-20, 71.4% [IOD] and 69.2%
denture satisfaction [CD] female
scale

Emami et al. To assess influence of Prospective, RCT N=173 patients Subjects with implants had a
201053 and sense of coherence on Assessment: before (implant-supported significantly higher
Jabbour et al. OHRQoL for implant- treatment, and 1 and 2 overdenture [IOD] improvement in OHRQoL
201269 supported years after treatment group: n=97; versus conventional dentures.
overdentures versus conventional denture There was no significant
conventional dentures Measures: OHRQoL, [CD] group: n=76) relationship between OHRQoL
and to determine the SOC and SOC. At both follow-ups,
Mean age: 72.1 yrs
stability and magnitude Instruments: OHIP-20, (range: 66–88 yrs) participants wearing implant-
of the effect on SOC-13 supported overdenture
OHRQoL 53,6% [IOD] and 53,9% reported significantly better
[CD] female total OHIP scores than those
wearing conventional
dentures.

Emami et al. Assessment of Prospective, clinical N=135 patients The study observed an
201576 OHRQoL in subjects study improvement in all seven
Mean age: 61.6 yrs
receiving mandibular domains of the OHIP-20 after
Assessment: before (range: not reported)
three-implant treatment and after receiving a mandibular three-
overdentures 68.1% female implant overdenture.
treatment
Measures: OHRQoL,
Denture satisfaction
Instruments: OHIP-20,
DSQ

Erkapers et al. To assess satisfaction Prospective, multicenter, N=51 patients Post-treatment there were
201154 after implant treatment clinical study significant improvements in
Mean age: 65.8 yrs
in atrophic maxilla Assessment: prior to (range: 47–83 yrs) total OHIP score and all OHIP
treatment and 12 weeks, 52.9% female subdomain scores on all
and 6 and 12 months occasions.
after treatment
Measures: OHRQoL
Instruments: OHIP-49

Fernandez- Assessment of Cross-sectional study N=193 (dentate patient Patients with implant-
Estevan et al. OHRQoL in patients group [DP]: n=57; supported overdentures has
Assessment: after
201577 with implant-supported treatment conventional complete significantly lower OHIP
overdentures and denture [CD] group: summary scores than patients
conventional complete Measures: OHRQoL n=56; implant- with conventional complete
dentures Instruments: OHIP-20, supported overdentures dentures. Level of impairment
OSS. [IOD] group: n=80 in patients with implants was
comparable to dentate
Mean age: 69.5 yrs [DP
controls.
and CD] and 69.6 yrs
[IOD]
57.2% [DP and CD] and
60.0% [IOD] female

32
Study (year) Aim Methods and design Subjects Summary findings
Geckili et al. To assess the impact Prospective, clinical N=78 patients Following implant treatment
201155 of two-implant retained study Mean age: not provided there was a significant
overdentures on improvement in OHIP-14 total
Assessment: prior to (range: 65–82 yrs)
OHRQoL score and all subscale scores.
treatment and 6 months Gender: not provided
after treatment OHQoL-UK total and all
subscales were also
Measures: OHRQoL significantly improved following
Instruments: OHIP-14, implant treatment.
OHQoL-UK

Geckili et al. To compare patient Cross-sectional study N=100 patients While patients in the implant
201262 satisfaction, quality of Assessment: 4 years (implant-supported treatment group were
life, and bite force with overdenture [IOD] significantly more satisfied
after treatment
respect to implant group: n=50; than patients with conventional
support for complete Measures: OHRQoL, conventional denture dentures, differences in
dentures satisfaction, bite force [CD] group: n=50) OHRQoL were only small and
Instruments: OHIP-14, Mean age: 67.9 yrs not significant.
VAS (range: 65–74 yrs)
62.0% [IOD] and 68.0%
[CD] female

Geckili et al. To assess the influence Cross-sectional study N=62 patients (2 The number of implants or
201279 and of masticatory function Assessment: 3 years implants with ball: attachment type were not
Mumcu et. al. and type / number of n=14; 2 implants with associated with patient
after treatment
201278 implants on patient Locator: n=14; 3 satisfaction but with OHRQoL.
satisfaction and quality Measures: OHRQoL, implants with ball: Lowest OHIP summary scores
of life of patients Satisfaction and n=12; 3 implants with were observed in patients with
wearing mandibular Maximum Bite Force bar: n=11; 4 implants 4-implant-supported bars.
implant-supported Instruments: OHIP -14, with bar: n=11
overdentures VAS Mean age: 64.0 yrs
(range: 42–90 yrs)
51.6 % female

Geckili et al. To assess the influence Prospective, clinical N=55 patients (ball Longer interimplant distance
201580 and of interimplant distance study attachments: n=22, was associated with better
Geckili et al. and momentary Locator attachments: OHRQoL. Furthermore, OHIP
Assessment: after
201581 retention forces on n=33 scores in the social disability
treatment
patient satisfaction and Mean age: 64.4 yrs and handicap domains were
QoL in subjects Measures: OHRQoL lower in subjects with higher
(range: not provided)
receiving mandibular Instruments: OHIP-14, retention forces.
overdentures VAS 56.4% female
supported by two
implants

Gjengedal et To compare OHRQoL Prospective, RCT N=54 patients (relined In edentulous patients
al. 201363 and HRQoL in conventional denture dissatisfied with their existing
Assessment: before
edentulous patients treatment, and 3 months [RCD] group: n=26; conventional complete
who were treated either and 2 years after implant-retained dentures, implant support
with a conventional treatment overdenture [IOD] resulted in substantial short-
relining of the existing group: n=28) term and middle-term
complete denture or by Measures: OHRQoL, improvements in OHRQoL
Mean age: 67 yrs
converting it into a HRQoL, general well- whereas conventional relining
being, coping strategies (range: 53–78 yrs)
implant-retained had no effect on OHRQoL.
[RCD] and 68 yrs
overdenture Instruments: OHIP-20, (range: 48–78 yrs) However, HRQoL, general
SF-36, WHO-Five Well- [IOD] well-being, and coping
Being Index, BACQ strategies were not affected by
65.4% [RCD] and either treatment option.
64.3% [IOD] female

33
Study (year) Aim Methods and design Subjects Summary findings
Harris et al. Determination of Prospective, multicenter N=122 patients While in patients dissatisfied
201364 differences in patient RCT (conventional denture with their existing conventional
satisfaction with [CD] group: n=62; complete dentures the
Assessment: baseline, 3
implant overdentures implant-retained provision with new ones
months after receiving
compared to conventional complete overdenture [IOD] already substantially improved
conventional complete dentures, and additional group: n=60) patient satisfaction and
dentures 3 months with Mean age: 64,4 yrs OHRQoL, implant treatment
conventional or implant- (range: not provided) led to further improvements in
patient perceptions. However,
supported complete 68.0% female no impact on HRQoL was
dentures
detected.
Measures: OHRQoL,
denture satisfaction,
HRQoL
Instruments: OHIP-49,
DSQ, SEIQoL

Heydecke et Assessment of the Prospective, RCT N=102 patients Following treatment,

al. 200557 impact of implants on (conventional denture improvements in OHRQoL
Assessment: before
social and sexual [CD] group: n=48; were reported for each group,
treatment and two
activities in subjects months after treatment implant-supported but improvement was
with new mandibular overdenture [IOD] significantly better for subjects
conventional complete Measures: OHRQoL, group: n=54) receiving implants versus
dentures or 2-implant social and sexual those receiving conventional
Mean age: 51.2 yrs
retained mandibular activities dentures. Conventional
[CD] and 50.8 yrs [IOD]
overdentures Instruments: OHIP-49, complete dentures are
(range 35–65 yrs)
SIQ associated with more negative
45.8% [CD] and 51.9% impacts on leisure and sexual
[IOD] female activities than implant
overdentures.

Melas et al. Comparison of Prospective, clinical N=83 patients (implant Compared to conventional
200182 OHRQoL between study overdenture [IOD] dentures patients with implant-
patients treated with Assessment: group: n=43; stabilized overdentures were
implant-stabilized conventional denture statistically significantly higher
posttreatment
overdentures and [CD] group: n=40) satisfied and experienced less
conventional dentures Measures: OHRQoL impact on daily life.
Mean age: 69.6 yrs
Instruments: OIDP [CD] and 63.7 yrs [IOD]
(range: not provided)
52.9% female

Mundt et al. Assessment of Retrospective study N=133 patients OHIP summary scores after
201583 OHRQoL, implant Assessment: Mean age: 71.2 yrs treatment were low, indicating
survival and prosthetic retrospective (range: 48–100 yrs) high OHRQoL.
aftercare of edentulous pretreatment (then test)
people treated with 59.4% female
and post treatment
mini dental implants for
stabilization of their Measures: OHRQoL
complete dentures Instruments: OHIP-14

Persic et al. Comparison of Cross-sectional study N=122 patients (4 mini- Patients with IODs supported
201672 OHRQoL in patients Assessment: 3–5 years implants [4MI] group: by 4 mini-implants had better
rehabilitated with three after treatment n=50; 2 implants with OHRQoL than those with 2
different types of locator [2IL] group: standard implants and bar-
Measures: OHRQoL
mandibular implant n=56; 2 implants with and locator-retained IODs.
overdentures after at Instruments: OHIP-14 bar [2IB] group: n=16)
least 3 years in function
Mean age: 66.7 yrs
[4MI], 61.9 yrs [2IL],
and 60.8 yrs [2IB]
62.3 % female

34
Study (year) Aim Methods and design Subjects Summary findings
Preciado et al. To validate QoLIP-10 Cross-sectional study N=150 patients Overall OHRQoL did not differ
201365 and to compare Assessment: (conventional complete significantly between patients
OHRQoL in patients approximately 1–16 yrs denture group: n=50; with conventional complete
with conventional after treatment implant-retained dentures, implant-retained
complete dentures, overdenture group: overdentures and hybrid
Measures: OHRQoL
implant-retained n=50; hybrid implant- implant-prostheses for both
overdentures and Instruments: OHIP-20, prosthesis group: n=50)instruments OHIP-20 and
hybrid implant- QoLIP-10
Mean age: not provided QoLIP-10.
prostheses
(range: 40–90 yrs)
64.0% female

Preciado et al To validate QoLIP-10 Cross-sectional study N=131 patients While OHRQoL measured with
201366 and to assess Assessment: at least 10 (implant-retained the summary scores of OHIP-
OHRQoL in patients months after treatment overdenture group: 14 and QoLIP-10 did not differ
with various types of n=38, hybrid implant- substantially between patient
Measures: OHRQoL,
screwed implant- prosthesis group: n=50,groups, hybrid prosthesis
dental satisfaction
prostheses implant-supported fixedwearers had lower OHRQoL in
Instruments: OHIP-14, partial denture group: some of the subscales, in
QoLIP-10, VAS 43) particular Dental-Facial
Aesthetics and Performance of
Mean age: not provided
the QoLIP-10 and Functional
(range: not provided)
Limitation of the OHIP-14.
57.3% female

Schoen et al. To assess impact of Prospective, clinical N=50 patients Implant-retained overdentures
200859 and mandibular implants on study were associated with
Mean age: 61.5 yrs
Korfage et al. OHRQoL and HRQoL improvements in OHIP scores,
Assessment: before (range 41–81 yrs)
201158 in patients with tooth which were more pronounced
treatment, 6 weeks, and 30% female
loss due to head and 1 and 5 years after in non-irradiated versus
neck cancer receiving treatment irradiated patients. Post-
mandibular implant- treatment QoL and OHRQoL
retained overdentures, Measures: OHRQoL, were worse in patients who
and to compare effects denture satisfaction, had undergone radiation
with respect to HRQoL therapy versus those who had
radiation Instruments: OHIP-49, not. In surviving patients, there
EORTC QLQ-C30 and was no significant change in
H&N35 OHIP scores from 1-year to 5-
year follow-up.

Sun et al. Evaluation of Prospective, clinical N=50 patients Implant-retained mandibular

201467 masticatory efficiency study overdentures significantly
Mean age: 62 yrs
and OHRQoL in Assessment: 1 month improved patients’ OHRQoL.
(range: 55–74 yrs)
patients with implant- before treatment, and 6 The improvement in OHRQoL
retained mandibular months after treatment 44.0% female was mainly due to a decrease
overdentures Measures: OHRQoL, in OHIP scores in the subscale
masticatory efficiency Functional Limitation, which
was correlated to
Instruments: OHIP-49
improvements in masticatory
efficiency.

Torres et al. To assess the impact Cross-sectional study N=100 subjects Subjects in the implant group
201160 of personality traits on Assessment: between 12 (conventional denture had significantly better OHIP
OHRQoL in patients and 48 months after [CD] group: n=50, scores in comparison with
with conventional treatment implant-supported those with conventional
mandibular Measures: OHRQoL, overdenture [IOD] dentures. Personality traits, in
overdentures versus personality traits group: n=50) particular neuroticism and
implant-supported Instruments. OHIP-14, Mean age: 64.2 yrs conscientiousness, were
mandibular NEO-FFI related to OHRQoL in both
[CD] and 61.8 yrs [IOD]
overdentures treatment groups.
(range: not provided)
52.0% [CD] and 48.0%
[IOD] female

35
Study (year) Aim Methods and design Subjects Summary findings
Vercruyssen Comparison of implant Prospective, RCT N=59 patients For both treatment groups a
et al. 201484 and patient outcome of Assessment: after Mean age: 58 yrs significant improvement in
guided and implant placement, OHRQoL was observed with
(range: 31–78 yrs)
conventional implant prosthesis instalment no differences between guided
placement and 1-year follow-up 52.0% female or conventional implant
Measures: OHRQoL placement.
Instruments. OHIP-49

Table 3 – Summary of factors potentially affecting implant-related treatment effects as identified in the
included studies

Factor Population Effect

Biological and clinical characteristics

Number of missing and Partly dentate A larger number of teeth replaced by dental implants is associated
replaced teeth43,44 patients with higher OHRQoL improvement.

Location of single implant Partly dentate Pre-treatment OHRQoL impairment and treatment-related OHRQoL
treatment27 patients improvement is highest for missing and replaced anterior teeth and
lowest for molars.

Condition of implant site}41 Partly dentate Implants in extraction sockets and in healed alveolar ridges result in
patients similar OHRQoL improvement.

Atrophy of the maxilla and Edentulous patients There is no difference between palatal positioned implants in severely
implant position70 atrophic maxillae and well-centered placed implants in the non-
atrophic maxilla in post-treatment satisfaction and OHRQoL.

Technical and treatment characteristics

Loading protocol31 Partly dentate OHRQoL improvement might be higher in patients with immediately
patients loaded implants than with conventionally loaded implants.

Implant dimension71.42,85 Partly dentate Implant diameter and implant length is not associated with treatment
patients effects.

Edentulous patients Treatment with mini-implants might result in higher OHRQoL and
satisfaction but considerably lower implant survival rates when
compared to standard diameter implants.

Retention51,72,86.78,79 Partly dentate Whether implant supported FDP are screwed or cemented does not
patients affect OHRQoL after implant treatment.

Edentulous patients Overdentures might be associated with lower OHRQoL when retained
by locators or bars than with ball ring matrices. Furthermore, implant-
supported FDP might be associated with in less psychosocial
discomfort and disability than implant-retained overdentures.

Personality and psychosocial characteristics

Neuroticism24,36,37,60 Partly dentate and Higher levels of neuroticism are associated with less satisfactory
edentulous patients effects of implant treatment in terms of OHRQoL.

Sense of coherence (SOC)53,69 Edentulous patients SOC is not associated with post-treatment OHRQoL.

OHRQoL before treatment48 Edentulous patients Only if OHRQoL is highly impaired at baseline, implant-support is
associated with higher treatment-induced OHRQoL improvement than
without implants.

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 Patient’s request47 Edentulous patients Only if patients request implants, implant-support is associated with
higher treatment-induced OHRQoL improvement than without
implants.

Behavior

Dietary advices52 Edentulous patients Customized dietary advices have no meaningful effect on OHRQoL.

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