Journal of Orthodontics

OnlineFirst
© The Author(s) 2024, Article Reuse Guidelines
https://doi.org/10.1177/14653125241255139

Clinical Section

The effectiveness of bone anchored maxillary protraction

(BAMP) in the management of class III skeletal
malocclusion in children aged 11–14 years compared with an
untreated control group: A multicentre two-arm parallel
randomised controlled trial

Nicky Mandall 1, Wesam Aleid 2, Richard Cousley 3, Edith Curran 1, Susi Caldwell 4,

Andrew DiBiase 5, Fiona Dyer 6, Simon Littlewood 7, Spencer Nute 8, Sarah Jayne

Campbell 9, Simon Atkins 10, Sherif Bayoumi 2, Vyomesh Bhatt 8, Paul Chambers 7, Nicholas
Goodger 5, Claire Bates 1, Ovais Malik 11, David Waring 9, and Paul Bassett 12

Objective: To evaluate the effectiveness of bone anchored maxillary protraction (BAMP) in the
management of class III skeletal malocclusion in children aged 11–14 years compared with an
untreated control group in terms of perceived need for orthognathic surgery, skeletal and dental
change, and psychological impact.
Design: A multicentre two-armed parallel randomised controlled trial.
Setting: Six UK hospital orthodontic units.
Methods: A total of 57 patients were randomly allocated into either the BAMP group (BAMPG)
(n = 28) or a no treatment control group (CG) (n = 29).
Outcomes: Data collection occurred at registration (DC1),18 months (DC2) and 3 years (DC3),
where skeletal and dental changes were measured from lateral cephalograms and study models.
Oral Aesthetic Subjective Impact Score (OASIS) and Oral Quality of Life (OHQOL)
questionnaires were used to assess the psychological impact of treatment.
Results: The mean age was 12.9 ± 0.7 years and 12.6 ± 0.9 years in the BAMPG and CG,
respectively. At DC2, the BAMPG achieved a class III ANB improvement of +0.6° compared
with −0.7° in the CG (P = 0.004). The overjet improvement was +1.4 mm for the BAMPG and
−0.2 mm for the CG (P = 0.002). There was no evidence of any other group differences for the
other skeletal or dental cephalometric outcomes (P > 0.05) or the questionnaire data (OASIS P =
0.10, OHQOL P = 0.75). At DC2, the 18-month follow-up, 22% of the BAMPG achieved a
positive overjet. At the 3-year follow-up (DC3), fewer patients in the BAMPG were perceived to
need orthognathic surgery (48%) compared with 75% of patients in the CG (P = 0.04), with an

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 odds ratio of 0.31 (95% confidence interval = 0.10–0.95).
Conclusion: The BAMP technique did not show any social or psychological benefits; however,
the skeletal class III improvement in ANB and the overjet change were sufficient to reduce the
perceived need for orthognathic surgery by 27% compared with the CG.

Keywords
class III skeletal pattern, bone anchored maxillary protraction, skeletal and dental outcomes,
randomised controlled trial

1 Tameside and Glossop Integrated Care NHS Foundation Trust, Manchester, UK

2 North Manchester General Hospital, Manchester, UK
3 The Priestgate Clinic, Peterborough, UK
4 South Manchester University Hospitals NHS Foundation Trust, Manchester, UK
5 William Harvey Hospital, Kent, UK
6 Charles Clifford Dental Hospital, Sheffield, UK
7 Bradford Teaching Hospitals NHS foundation Trust, Bradford, UK
8 Southend University Hospital NHS Foundation Trust, Southend, UK
9 University Dental Hospital of Manchester, Manchester, UK
10 The University of Sheffield School of Clinical Dentistry, Sheffield, UK
11 Salford Royal Hospitals NHS Trust, Salford, Manchester, UK
12 Consultant Statistician, Amersham

Corresponding author(s):
Nicky Mandall, Tameside and Glossop Integrated Care NHS Foundation Trust, Fountain Street, Ashton-under-Lyne,
Manchester OL6 9RW, UK. Email: nicky.mandall@tgh.nhs.uk

Introduction
Treatment for young children with a skeletal class III malocclusion can be limited to an upper
arch alignment while waiting until facial growth is mostly complete, before offering either
orthodontic camouflage or orthognathic surgery. Skeletal surgical bone anchor systems have
been described for young teenagers, either for absolute orthodontic anchorage or for orthopaedic
maxillary protraction (Choi et al., 2005; Cornelis et al., 2008a; De Clerck et al., 2002, 2009;
Eroglu et al., 2010; Heymann et al., 2010; Kircelli and Pektas, 2008; Liou, 2005; Mommaerts et
al., 2005; Singer et al., 2000; Sugawara and Nishimura, 2005).
The bone anchored maxillary protraction (BAMP) technique consists of miniplates in the
anterior zygomatic arches and distal to the lower permanent canines (Figure 1) with full-time
class III elastics (150–200 g) to protract the maxilla. De Clerck et al. (2010) showed a mean
sagittal maxillary improvement of 5.2 mm in consecutively treated BAMP cases, which was 3.9
mm better than an untreated group (P < 0.001). The overjet correction was 3.8 mm more than in
the untreated group (P < 0.001). Similarly, Nguyen et al. (2011) reported a forward maxillary
displacement of 3.7 mm and 4.3 mm upper incisor movement. Slightly larger treatment effects
were seen after a randomised controlled trial (RCT) using a modified technique of palatal

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 miniscrew-anchored maxillary protraction (MAMP) (Kamel et al., 2023) with 4.34 mm of
maxillary protraction and an ANB improvement of 5.5°. Van Hevele et al. (2018) showed
smaller BAMP SNA and ANB improvements of 1.9° and 1.4°, respectively. Skeletal effects were
also shown at the circum-maxillary sutures, pterygomaxillary fissure (Baccetti et al., 2010) and
the glenoid fossa (De Clerck et al., 2012; Yatabe et al., 2017a) and were reflected in
improvements in the upper lip, cheeks and midface soft tissue (Elnagar et al., 2017a). The BAMP
technique is also effective for children with unilateral cleft lip and palate (Faco et al., 2019 Ren
et al., 2019; Yatabe et al., 2017b) and successfully improves the airway in young patients with
obstructive sleep apnoea (Quo et al., 2019).

Figure 1. The BAMP plates and class III elastics.

When maxillary protraction treatments are compared, BAMP appears to be more effective than a
tooth-borne protraction facemask (Cevidanes et al., 2010; Cha and Ngan, 2011; Elnagar et al.,
2017b; Sar et al., 2011). A systematic review (Feng et al., 2012) reported a mean of 3.08 mm
forward movement of A point in the BAMP group compared with untreated controls (P < 0.001)
and BAMP was 1.4 mm more effective than a protraction facemask (P = 0.003). Another
systematic review (Morales-Fernandez et al., 2013) showed the BAMP protraction effect was on
average 5.2 mm compared with 0.81 mm for a protraction facemask. They also reported a mean
angular skeletal change in the BAMP patients of 2.53° protraction at A point, a 1.93° retraction
at B point and a class III improvement of 4.46°. It is interesting to then consider the meta-
analysis by Cornelis et al. (2021) that suggested a bone-anchored facemask (ANB correction
4.2°) and BAMP with class III elastics (ANB correction 3.5°) seemed to deliver a similar

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 maxillary protraction effect.
Although there is evidence to support the effectiveness of BAMP and comparison with other
maxillary protraction treatments, we aimed to prospectively randomise to compare BAMP with
an untreated control group and to further evaluate the need for orthognathic surgery with a long-
term follow-up.
Therefore, the aim of the present study was to evaluate the effectiveness of BAMP in children
aged 11–14 years, compared with an untreated control group, in terms of skeletal and dental
change, psychological impact and the need for orthognathic surgery. The null hypothesis stated
that there was no difference in the effectiveness of BAMP in children aged 11–14 years,
compared with an untreated control group, in terms of skeletal and dental change, psychological
impact and the need for orthognathic surgery.

Methods
The study was a multicentre two-arm parallel RCT with a 1:1 allocation ratio for two groups. No
changes to the trial were made after commencement.

Participants
Inclusion criteria. The inclusion criteria were as follows: White Caucasian children aged 11.5–
14.0 years (the lower age limit was advised particularly for girls where lack of bone density
increases the risk of plate failure); a class III skeletal pattern with maxillary retrusion; a reverse
overjet of at least −1 mm with three or more incisors in crossbite in retruded contact position;
lower permanent canines and first premolars erupted (to allow space for the lower plates after
orthodontic root divergence); and dentally fit and excellent oral hygiene (to reduce the risk of
postoperative infection).

Exclusion criteria. The exclusion criteria were as follows: cleft lip and/or palate or craniofacial
syndrome (maxillary soft tissue scarring may reduce the effect of maxillary protraction); a
reverse overjet greater than −6 mm (De Clerck et al. (2010) showed a mean overjet correction of
4 ± 1.9 mm, suggesting a maximum overjet correction achievable with this technique of
approximately 6 mm; a forward mandibular displacement on closure (the presence of a forward
mandibular displacement on closure in some of the patients may complicate the statistical
analysis); a maxillary mandibular planes angle >38° (the BAMP treatment may have resulted in a
downwards and backwards mandibular rotation and increase in lower face height); mandibular
asymmetry; muscular dystrophy (associated with increased lower face height and it was possible
the BAMP technique could further increase the lower face height); previous radiotherapy to
jaws; previous or current treatment with bisphosphonates; and smoking (these factors may affect
surgical infection and healing).

Study setting

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 Patients were recruited from general dental practitioner referrals to orthodontic departments at
six UK hospitals: Tameside General Hospital, Manchester (n = 15); Wythenshawe Hospital,
Manchester (n = 8); Southend University Hospital (n = 2) and Charles Clifford Dental Hospital,
Sheffield (n = 11); William Harvey Hospital, Kent (n = 11); and St Luke’s Hospital, Bradford (n
= 10). The consultant orthodontist at each site was the local principal investigator (PI) and was
responsible for patient recruitment and consent. The approvals obtained were novel BAMP
technique, ethics committee (MREC 15/NW/0022) and Research and Development. Patients
were registered between March 2016 and October 2019.

Clinical intervention and clinical endpoint

Patients were randomly allocated to either receive the surgical intervention in the BAMP group
(BAMPG) or no treatment in the control group (CG). The BAMPG received a surgical and
orthodontic standard operating procedure (SOP) (Table 1) following advice from Professor
Mommaerts. DB Orthodontics supplied the Surgitec single-use titanium plates and screws (CE
mark 0499). All the BAMPG patients received the clinical intervention. If the overbite was deep,
the occlusion was propped as clinically indicated to allow forward maxillary movement and
overjet correction. A lower removable appliance was used: Adam’s cribs on the lower first
molars and a Southend clasp on the lower central incisors with occlusal acrylic in the buccal
segments to prop the bite open.

The clinical endpoint was defined as achieving a positive overjet of 1 mm or more. If the clinical
endpoint was not reached, elastic wear continued until the DC2 timepoint, 18 months after the

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 baseline registration, at which point the plates were removed.
Between the DC2 and DC3 timepoints, if the consultant orthodontist considered an upper
fixed appliance was clinically indicated, then this was carried out and documented. The use of an
upper fixed appliance was then accounted for in the statistical analysis.

Outcome measures
Primary outcome measure: Perceived need for orthognathic surgery. The primary outcome
measure was the need for orthognathic surgery. The evaluation of perceived clinical need for
orthognathic surgery was assessed by a group of three consultant orthodontists who were not
involved in the BAMP clinical trial delivery (CB, OM, DW) who discussed and reached a
consensus regarding the perceived need for orthognathic surgery as ‘yes’ or ‘no’. They assessed
blinded DC3 records: extra-oral and intra-oral photographs; clinical overjet measurement; and
cephalometric measures. The following factors were used for orthognathic decision making: the
extent of skeletal class III (SNA, SNB and ANB); dentoalveolar: incisor inclinations
(compensation), overbite, anterior crossbite; and soft tissues: facial profile, peri-alar recession,
upper labial flatness, nasolabial angle, facial convexity, chin prominence and chin/neck distance.

Secondary outcome measures: Orthodontic cephalometric skeletal and dental overjet

changes and psychological impact. The clinicians were blind to the treatment allocation when
the cephalometric and study models were measured. NM used a standard Eastman analysist to
assess skeletal changes. SC measured maxillary rotation by superimposing on the anterior
zygomatic process identified as a stable structure by Bjork (1977) and mandibular rotation by
superimposing on the inner border of the mandibular symphysis and the inferior dental (ID)
canal (Bjork and Skieller, 1983). Study model overjet was measured by NM using a steel
millimetric ruler to the most prominent upper permanent incisor. To minimise random error,
three measurements were taken and the mean values calculated. Intra-examiner reliability was
assessed by re-measuring 20 radiographs and 20 study models at least 1 week apart. Quality of
life was assessed using the Oral Health Quality of Life (short form) CPQ11-14 questionnaire
(Jokovic et al., 2002, 2006) and the Oral Aesthetic Subjective Impact Scale (OASIS) (Mandall et
al., 2000). Data collection was carried out at baseline registration (DC1), 18 months later (DC2)
and 3 years after registration (DC3). All active treatment in the BAMPG was completed by DC2.
Between DC2 and DC3, the patients were offered an upper fixed appliance, if clinically
indicated, as routine care that would normally be offered could not be withheld.

Secondary outcome measures: Surgical. For the BAMPG only, the patient recorded daily
postoperative discomfort for 2 weeks (9-point Likert scale where 1 = no pain and 9 = severe
pain). The surgeons recorded theatre operating time, in minutes, from first flap incision to final
suture placement, postoperative infection rates and plate failure rates. There were no changes to
the trial outcomes after the trial commenced.

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 Sample size calculations
Primary outcome need for orthognathic surgery. In a trial investigating protraction headgear
(Mandall et al., 2016), 67% of patients in the CG needed orthognathic surgery and we assumed it
would be similar for the CG in this trial. Of the patients receiving protraction headgear, 33%
needed surgery; however, as BAMP treatment is more effective, it was suggested that 25% of the
BAMP group would need orthognathic surgery. A sample size of 26 individuals in each group
would have an 80% power for a two-sample comparison of a difference in proportions of 0.42
for patients requiring orthognathic surgery (the difference between a BAMPG proportion of 0.25
and a CG proportion of 0.67) using a two-group test with a 0.050 two-sided significance level.

Secondary outcome overjet. De Clerck et al. (2010) showed a mean correction of 4 mm for
BAMP and −0.1 mm for a matched historical control. Using these data, a sample size of 4 in each
group will have an 80% power to detect a difference in means of 4 mm (the difference between a
BAMPG treatment mean overjet improvement of 4 ± 1.9 mm and a CG improvement of 0 ± 0.6
mm) using a two-group t-test with a 0.05 two-sided significance level.
Therefore, using the larger sample size calculation for the primary outcome (need for
orthognathic surgery), 26 patients in each group meant the total sample size needed for this trial
was 52. A total of 57 patients were to be recruited, allowing for an 8% attrition.

Random allocation method

After patients and parents had signed the consent, they were randomly allocated to the BAMPG
or the CG. The random allocation sequences were generated by NM using restricted
randomisation with different sized blocks to ensure equal group sizes. Stratification for sex
ensured the skeletal outcomes were not confounded by different growth spurt timing. The
randomisation sequences were concealed in opaque envelopes and kept at the coordinating
centre. After consent, the PI telephoned the coordinating centre and the group allocation was
revealed.

Blinding
It was not possible to blind the operator or the patients to the treatment allocation. However, this
trial was single blind, for observers measuring the radiographs and study models and the
statistician were blind to the treatment allocation until the analysis was completed.

Stopping rules
This was defined as identification of a problem with the BAMP surgical procedure, such as
excessive pain, relapse or patient dissatisfaction.

Patients leaving the study or refusing treatment

An intention-to-treat analysis was carried out so, even if a patients in the BAMPG dropped out of

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 treatment, it was planned to collect DC2 and DC3 data. It was not possible to collect data for
patients who did not attend their appointments.

Statistical analysis
SPSS version 25 (IBM Corp., Armonk, NY, USA) was used. A descriptive analysis was carried
out of the demographic characteristics of the study participants in each group. The Bland–
Altman levels of agreement and the intraclass correlation (ICC) were used to examine intra-
examiner reliability. Changes in the outcomes over time were calculated from DC1 to DC2 and
then DC2 to DC3 and the changes compared between the BAMPG and the CG. For most of the
outcomes, the analyses were performed using analysis of covariance (ANCOVA). In these
analyses, the DC2 or DC3 value was considered to be the outcome value, with the equivalent
outcome at baseline (DC1) included as a covariate. The exception to this method of analysis was
for maxillary and mandibular rotation. For these outcomes, there were no baseline values, and so
an unpaired t-test was used to compare the BAMPG and CG. All analyses were carried out at a
level of significance of 0.05.

Results
Patients were recruited into the trial and randomised into the BAMPG (n = 28) or CG (n = 29).
Figure 2 shows the trial profile and the dropouts from each group because of non-attendance. An
intention-to-treat analysis was carried out and all patients allocated to the BAMPG received the
surgical intervention. Baseline characteristics are shown in Table 2 and it was considered that
pre-treatment equivalence occurred, since there was insufficient evidence of a difference between
the BAMPG and the CG.

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 Figure 2. Trial profile CONSORT 2010 flow diagram.

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 Descriptive statistics
Demographics. The mean age in the BAMPG was 12.9 ± 0.7 years and in the CG it was 12.6 ±
0.9 years. Overall, approximately two-thirds of patients were boys and one-third third were girls.

Reliability. Reliability was measured for all cephalometric and dental overjet measurements. The
intra-examiner reliability was high. For the 95% limits of agreement, this ranged from the
narrowest limits of −0.4 to 0.5 through to the widest limits of −3.7 to 4.0. For the ICCs, the
lowest value was 0.91 (95% confidence interval [CI] = 0.79–0.96) and the highest value was
0.99 (95% CI = 0.98–1.00).

Surgical data. The mean time to place the BAMP plates was 88 ± 65 min and the mean

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 postoperative pain score was 2.4 ± 0.67). The plate infection rate was 11.1% (a mix of upper and
lower plates) and the plate failure rate, defined as requiring replacement, was 8.3%, exclusively
in the upper. In total, 7 (26%) patients returned to theatre once to have an upper plate replaced
and 1 (4%) patient had two upper plates replaced. Loss of a single screw or gingival overgrowth
or a screw dehiscence were observed in 4 (15%) patients.

Orthodontic data. The mean class III elastic force used for the BAMPG was 193 ± 26 g. The
mean time in elastics was 11.4 ± 2.8 months carried out over six outpatient visits (range 6–7
visits). In 33% of patients, it was necessary to prop the occlusion with a lower removable
appliance and posterior occlusal bite blocks.

Clinical and psychological changes DC1 (baseline) to DC2 (18-month follow-up). Table 3
shows the mean SNA moved forwards in the BAMPG by 1.1° ± 1.7° compared with 0.4° ± 0.9°
in the CG (P = 0.05; 95% CI = 0.0–1.5). Small changes in mean SNB occurred where the
BAMPG moved forwards by 0.5° ± 1.3° compared with 1.1° ± 2.0° in the CG (P = 0.16; 95% CI
= −1.6–0.3). For ANB, the BAMPG improved (became less class III) by a mean of 0.6° ± 1.3°
and the CG worsened by −0.7° ± 1.2° (P = 0.004; 95% CI = 0.3–1.7). No other cephalometric
measures showed a statistically significant difference between groups. Over time, the CG
negative overjet worsened by −0.2 ± 1.1 mm and the BAMPG overjet improved by 1.4 ± 2.1 mm
(P = 0.002; 95% CI = 0.6–2.4). There were no statistically significant differences between the
BAMPG + CG for the psychological/social questionnaires (OHQOL P = 0.75; OASIS P = 0.10).

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 The perceived need for orthognathic surgery (DC3). Patients were assessed regarding
perceived need for orthognathic surgery at DC3, or 3 years after baseline registration. Therefore,
the mean age in the BAMPG was 15.9 years and in the CG it was 15.6 years. An important
finding was that statistically significantly fewer patients in the BAMPG were perceived to need
orthognathic surgery (48%) compared with the CG (75%) (P = 0.04). This is also clinically
significant, indicating a 27% reduction in the perceived need for orthognathic surgery for
children who received BAMP treatment. The odds ratio (expressed as BAMP/control) was 0.31
(95% CI = 0.10–0.95); therefore, for a group of patients, the BAMPG had approximately one-
third of the odds of needing orthognathic surgery as the control group.

Clinical and psychological changes DC2 (18-month follow-up) to DC3 (3-year follow-
up). Table 4 summarises the skeletal and overjet changes from DC2 to DC3. A reduced dataset is
shown because the other cephalometric variables changed approximately by 1° over the DC2 to
DC3 period and the changes were neither clinically nor statistically significantly different
between groups (P > 0.05). No rotational changes occurred in the BAMPG compared with the

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 CG at any timepoint. SNA and SNB showed approximately 1° of forward growth from 18
months to 3 years in both groups (P > 0.05). Similar trends were seen for overjet change with the
BAMPG improving 0.6 mm and the CG improving 0.1 mm (P > 0.05). There were improved
psychological outcomes for OHQOL where the BAMPG showed a 3-point reduction in the
impact of their malocclusion compared with an increased score of 5 points in the CG (P = 0.02;
95% CI = −18.6 to −1.9).

The potential confounding effect of increased use of an upper fixed appliance in the BAMPG
DC2 to DC3. Between DC2 and DC3, 52% of the BAMPG received an upper fixed appliance
compared with 25% of the CG. As more patients in the BAMPG received an upper fixed
appliance than in the CG, this may have influenced the tendency for the BAMPG overjet to
improve from −1.2 mm at DC2 to −0.6 mm at DC3 whereas the CG showed no overjet
improvement during this time. Observation of the inclination of the upper incisors (Table 4) did
not suggest the fixed appliance had proclined the upper incisors more in the BAMPG to explain
the overjet improvement. Further ANCOVA testing did not indicate that the increased use of an
upper fixed appliance influenced the overjet improvement in the BAMPG compared with the CG
(P = 0.09). In contrast, the mean difference between groups for the change in the OHQOL
questionnaire DC2-DC3 was influenced by the use of an upper fixed appliance (P = 0.04). In
other words, the increased use of an upper fixed appliance in the BAMPG during DC2-DC3 is
more likely to explain the improved OHQOL score. This is particularly since the DC3 3-year
follow-up data were collected after the fixed appliance was debonded, where OHQOL scores
would be expected to improve at the end of treatment.

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 Discussion
This trial has shown that the BAMP treatment results in a small but favourable improvement in
ANB and overjet for class III skeletal malocclusions in children aged 11.5–14 years. An example
of the type of changes are shown in Figure 3. At the 3-year follow-up, just before the age of 16
years, the BAMPG had a 27% lower perceived need for orthognathic surgery compared with the
untreated CG. This is the first RCT to report a long-term perceived need for orthognathic surgery
outcome.

Figure 3. (a) Baseline DC1. (b) After 9 months of elastic wear. (c) DC3, at the 3-year follow-up.

Comparison with previous literature

The BAMPG skeletal and dental changes in this trial at DC2 were favourable compared with the
untreated CG but were smaller than the changes shown in a systematic review by Morales-
Fernandez et al. (2013). They reported a 2.53° protraction of A point of compared with 1.1° in
this trial, a −1.93° retraction of B point (in this study, B point moved forward +0.5°) and a mean

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 class III ANB improvement of 4.46° (0.6° in this study). However, the BAMP treatment effect is
more favourable than this latter value would suggest when compared with a worsening of ANB
of −0.7° in the CG, giving an overall ANB treatment effect of 1.3° (the difference between +0.6°
BAMPG and −0.7° CG). The change in overjet for the BAMPG in this trial was on average +1.4
mm and smaller than the +4 mm movement reported by De Clerck et al. (2010). It is possible
that the reason for the smaller ANB and overjet improvements was a result of the prospective
and randomised methodology. Prospective randomisation should minimise potential selection,
information or confounding bias that may result in reporting larger treatment effects.
A further explanation for the smaller skeletal changes shown in this trial could be the
difference in healthcare systems. Private healthcare may result in increased motivation and
children wearing their elastics more successfully. It was not possible for us to accurately measure
compliance with elastic wear, although 3 (12%) patients in the BAMPG were recorded as
struggling with elastic wear.
A further factor that may limit compliance with elastic wear could be loose or infected plates.
The plate infection rate in this study was 11.1%. Our plate failure rate was 8.3% and compared
favourably with the range of 6.6%–38.5% for the same pre-drilled self-tapping technique
(Cornelis et al., 2008a; Mommaerts et al., 2014; Van Hevele et al., 2018). Therefore, it seems
unlikely that the plate failure rate in this study could have influenced elastic wear enough to
explain the smaller skeletal movements.

Study design and limitations

The prospective RCT study design was used with the aim of comparing the effects of the BAMP
technique with a no treatment CG and with long-term follow-up to establish whether BAMP
reduced the perceived need for orthognathic surgery. The patients were all registered after
referral to a hospital setting, so the sample and therefore the findings should be generalisable to
the class III population aged 11–14 years. The BAMP technique was a relatively new procedure
for the surgical team, and it was possible that the time in theatre would reduce as the trial
progressed. Further calculations showed around a 10-min difference for the patients in the first
half of the trial (93.8 min) compared with the second half (82.6 min).
Although the patients were randomised, and all characteristics should be similar between the
two groups, it was notable that more patients in the BAMPG compared with the CG received an
upper fixed appliance between DC2 and DC3 (52% vs. 25%). Some unconscious operator bias
may have occurred to try to ensure the treated group achieved a positive overjet by placing an
upper fixed appliance more frequently in the BAMPG. Use of an upper fixed appliance,
however, was not shown to have influenced the amount of overjet change achieved in the
BAMPG more than the CG. In contrast, the data supported the improved OHQOL scores at DC3;
this could have been because the patients were pleased with the aesthetic effect of the upper
fixed appliance rather than the BAMP treatment per se. This lends some weight to the positive
effect of orthodontic fixed appliances on oral health quality of life (Javidi and Trill, 2023; Javidi

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 et al., 2017).
A further consideration is that we did not collect data on whether the patient might consider
orthognathic surgery when they are older through longer-term follow-up. This study did not
establish who went ahead with orthognathic surgery. As the final data were completed just before
the age of 16 years, there is also likely to be further class III growth in many of the patients; this
may affect their decision to go ahead with surgery at a later date. With further class III growth, it
may also be possible that more patients would clinically be perceived to need orthognathic
surgery so this study may have underestimated this outcome at the DC3 time point.

Risk/benefit
A number of factors will influence the risk/benefit considerations for the BAMP technique. It
was observed that all the plate failures occurred in the upper plates and this was not surprising
given that they are technically more difficult to place because of the anatomy of the anterior
zygomatic arch and the proximity to the maxillary sinus where the bone is thinner. A prospective
RCT compared MAMP, a palatal mini-screw supported hybrid hyrax screw and a bone supported
mandibular bar, and an untreated CG (Kamel et al., 2023). They showed favourable mean ANB
changes of 5.5° in the MAMP group compared with a worsening of −0.61° in the CG at 12-
month follow-up. This is supported by the meta-analysis carried out by Cornelis et al. (2021),
who showed a bone anchored facemask treatment delivered similar maxillary protraction to
BAMP with class III elastics. These findings would support the use of palatal mini-screw
retained RME (MAMP) rather than the upper miniplates being sited in the anterior zygomatic
arches used in this study. This would also benefit the patient in terms of shorter operating time,
less surgical morbidity and recovery time, and a reduced need for repeat surgery to replace loose
upper plates.
There was a complication for one patient in the BAMPG because of COVID-19 pandemic
delays. As they waited 18 months to have the plates removed, one lower plate was ankylosed
with significant bony overgrowth. It was left in-situ subgingivally but highlights the need to
remove the plates soon after elastic wear is completed.
Postoperative discomfort scores are also considered a risk. Patients and parents should be
aware of postoperative discomfort as part of informed consent. The discomfort levels recorded
were similar to previous reports (Cornelis et al., 2008b), so we can be reassured that pain levels
are low with the BAMP technique. Cornelis et al. (2008a) reported the time in surgery for plate
placement as 15–30 min per plate and this compares favourably with our data (mean time to
place four plates was 88 min).
It is also important that the BAMP treatment in this trial did not show a demonstrable patient
psychosocial benefit. This could be explained by the small skeletal and overjet changes that,
although noticed by clinicians, may not be as obvious to the patients.

Clinical relevance of the study findings

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 The finding that the BAMPG was perceived to need orthognathic surgery in 48% of cases
compared with 75% in the CG is clinically significant and, arguably, BAMP, or a modified
technique (MAMP) as discussed earlier, should be routinely considered offered to children aged
11.5–14 years with a class III skeletal pattern. An added advantage of MAMP is the ability to
expand the upper arch during maxillary protraction. Consideration should be given to the
relatively small skeletal and overjet improvements and perhaps this technique might be limited to
those patients requiring smaller movements to achieve a positive overjet.
The reduced perceived need for orthognathic surgery in the BAMPG is difficult to explain,
particularly as our skeletal movements were smaller than those of other studies. However, the
decision about perceived need for orthognathic surgery was taken at the DC3 timepoint. The
DC3 values for ANB and overjet at DC3 would help explain the reduced perceived need for
orthognathic surgery in the BAMPG. The ANB value for the BAMPG at DC3 was −2.4° and in
the CG it was −3.9°. The final DC3 overjet in the BAMPG was −0.6 mm and in the CG it was
−3.1 mm. This is supported by the descriptive statistic that 22% patients in the BAMPG had
achieved a positive overjet at DC2, and at DC3, 37% had a positive overjet. The improvement in
positive overjet DC2 to DC3 cannot be explained by upper or lower incisor inclination changes.
It seems more likely that the skeletal effect of ANB improvement in the BAMP group is
maintained at the 3-year follow-up and contributes to a more favourable overjet at DC3.

Further research and dissemination of findings

The risk/benefit balance when offering a surgical-orthodontic intervention should weigh more
heavily towards the benefits of treatment. For this reason, further research would be helpful to
evaluate the psychological benefit of all types of surgical orthodontic treatments as well as to
investigate further the patient and parent treatment burden and a detailed cost analysis of the
BAMP or MAMP techniques compared with orthognathic surgery. To further disseminate this
technique, training courses are planned, and a conference presentation has been delivered to
hospital orthodontic consultants who are able to take this technique forwards with their
maxillofacial surgeon teams nationally.

Conclusion
The BAMP technique did not show any social or psychological benefits; however, the skeletal
class III improvements in ANB and overjet change were sufficient to reduce the perceived need
for orthognathic surgery by 27%.

Acknowledgments
The authors thank Professor M Mommaerts, oral and maxillofacial surgeon, for his advice regarding
surgical technique.

Declaration of conflicting interests

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Page 17 of 21
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 The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or
publication of this article.

Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or
publication of this article: The trial was funded by the British Orthodontic Society Fund (BOSF) and by DB
Orthodontics.

ORCID iDs
Nicky Mandall https://orcid.org/0000-0003-4888-0804
Richard Cousley https://orcid.org/0000-0002-7393-4029
Andrew DiBiase https://orcid.org/0009-0003-5674-0630

Note
Trial registration Trial registry ISRCTN 93900866

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