Prosthodont Res Pract 6 : 209-216, 2007

PRACTICE GUIDELINE

Guideline for Denture Relining

Hiroshi Shiga, BEng, DDS, PhD,a,b Yoshihiro Terada, DDS, PhD,a,c
Kazunori Ikebe, DDS, PhD,a,d Yasumasa Akagawa, DDS, PhD,a,e
Toshihiro Hirai, DDS, PhD,a,f and Hiroshi Inoue, DDS, PhDa,g
a
Japan Prosthodontic Society, Tokyo, Japan
b
Department of Partial and Complete Denture, School of Life Dentistry at Tokyo, The Nippon Dental University,
Tokyo, Japan
c
Section of Fixed Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University,
Fukuoka, Japan
d
Division of Oromaxillofacial Regeneration, Osaka University Graduate School of Dentistry, Osaka, Japan
e
Department of Advanced Prosthodontics, Division of Cervico-Gnathostomatology, Programs for Applied
Biomedicine, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
f
Department of Removable Prosthodontics, Health Sciences University of Hokkaido School of Dentistry,
Ishikari-Tobetsu, Japan
g
Department of Removable Prosthodontics and Occlusion, Osaka Dental University, Osaka, Japan

cause of the specific nature of dental treatment

1. Introduction and dentistry, it is difficult to conduct studies
With the increasing attention to oral health in designed to provide the evidence for each treat-
recent years, the number of residual teeth re- ment in this field. Because of these limitations,
tained by individuals has been increasing with we prepared this set of guidelines on the basis of
each generation. According to the survey of den- limited evidence obtained by searching for scien-
tal diseases in 2005, the percentage of individu- tific papers and consensus among specialists.
als between 80 and 84 years of age retaining 20 This guideline will have to be periodically
or more teeth was 21.1%, thus exceeding 20% for modified when additional rationales or clinical
the first time since this survey was started. The findings are revealed in scientific clinical studies.
survey in 2005, however, showed that there was
still a high percentage of individuals with mul-
tiple missing teeth, i.e., individuals using den-
tures.
2. Procedure for preparing the
It is well known that the alveolar ridge inevi-
guideline
tably undergoes resorption with advancing age, 1) Identification of questions
irrespective of whether or not the individual uses The Guideline Preparing Committee was set up
dentures. For this reason, dentures are destined and tried to identify the questions for relining.
to show deterioration in fit no matter how well
they are initially prepared. Means available to 2) Literature search
deal with loss of denture fit are fabricating new From papers written in Japanese listed in the
dentures or relining. Relining can reduce the fre- Japana Centra Revuo Medicina for the period
quency of a patient’s visits and medical expenses 1983-2005 and papers written in English listed
as compared to fabricating new dentures. in the MEDLINE for the period 1982-2005, mem-
Under such circumstances, the Japan Prosth- bers of the Guideline Preparing Committee and
odontic Society decided to prepare relining guide- the Abstract Preparing Committee of the Japan
lines. When preparing this set of guidelines, we Prosthodontic Society selected those pertaining
followed the procedures for preparing evidence- to relining, using the following search algorithm.
based clinical practice guidelines. However, be- After reviewing these selected papers, the Com-
 mittee selected those to be adopted into the
Corresponding to: Japan Prosthodontic Society
guidelines.
1-43-9 Komagome, Toshima-ku, Tokyo 170-0003, Japan
Tel: +81-3-5940-5451, Fax: +81-3-5940-5630
E-mail: hotetsu-gakkai01@max.odn.ne.jp

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 Shiga et al., Prosthodont Res Pract 6 : 209-216, 2007

Japana Centra Revuo Medicina: January 1983 (9) A AND (direct technique OR direct method
through December 2005 OR direct relining OR indirect technique OR
Search formula indirect method OR indirect relining): 15 pa-
(1) A: 575 papers pers
(reline or relining or lining) or (rebase or re- (10) A AND (light-polymerizing OR light-polym-
basing) erized OR light-curing OR light-cured OR
((reline/AL or (rebasing method/TH or relin- autopolymerizing OR autopolymerized OR
ing/AL) or (rebasing method/TH or lining/ chemically-curing OR chemically-cured OR
AL) or (rebasing method/TH or rebase/AL) heat-polymerizing OR heat-polymerized OR
or rebasing/AL)) AND (PT=original paper heat-curing OR heat-cured): 93 papers
SB=dentistry) (11) A AND (soft denture liners OR soft reline
(2) A and Meta-Analysis: 0 papers materials OR resilient denture liners OR re-
(3) A and Randomised Controlled Trial: 2 pa- silient reline materials): 250 papers
pers (12) A AND (hard denture liners OR hard reline
(4) A and Cohort Studies: 0 papers materials): 83 papers
(5) A and (examination or diagnostic testing): (13) A AND (physical properties OR mechanical
12 papers properties): 78 papers
(6) A and (indication or contraindication): 6 pa- (14) A AND (curing temperature OR polymeriz-
pers ing temperature): 16 papers
(7) A and (direct method or indirect method): 24
papers 3) Determining the grade of recommendation
(8) A and (light-polymerizing or autopolymeriz- The grade of recommendation for each compo-
ing or thermal polymerization): 114 papers nent of the guideline is shown below.
(9) A and soft lining material: 117 papers
Grade Description Remark
(10) A and hard lining material: 3 papers
a Strongly recommended Evidence level I or II is
(11) A and physical properties: 56 papers
(based on firm evidence) available
(12) A and temperature: 21 papers
b Moderately recommended Evidence level III or IV is
(based on moderate evi- available
MEDLINE: January 1982 through December dence)
2005 c Recommendable Evidence level V or VI is
Search formula (based on weak evidence) available
(1) A: 524 papers Cross-sectional study is
available
Denture Liners[MeSH Terms] OR Denture Data from basic experi-
Rebasing[MeSH Terms] ments available
Denture Liners[MeSH Terms]: d Not recommended Disproof available
Denture Liner, Liner(Denture), Liners
(Denture), Cushion Liners, Cushion Liner,
Liner(Cushion), Liners(Cushion) Evidence level
Denture Rebasing [MeSH Terms]: I: Systematic reviews and meta-analyses of
Denture Rebasings, Rebasing(Denture), randomized controlled trials
Rebasings(Denture), Denture Relining, II: Randomized controlled trials
Denture Relinings, Relining(Denture), III: Non-randomized intervention studies
Relinings(Denture) IV: Observational studies
(2) A AND Meta-Analysis: 2 papers V: Non-experimental studies
(3) A AND Randomized Controlled Trial: 10 pa- VI: Expert opinion
pers
(4) A AND Controlled Trial: 16 papers 4) Preparation and evaluation of the guideline
(5) A AND Cohort Studies: 36 papers On the basis of papers selected by members of
(6) A AND Case Control Studies: 8 papers the Relining Guideline Preparing Committee,
(7) A AND (examination OR diagnostic testing): this set of guidelines was prepared, and then
25 papers modified after evaluation by members of the Re-
(8) A AND (indication OR contraindication OR lining Guideline Evaluation Committee.
applicability OR adaptability): 4 papers

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 Guideline for Denture Relining

3. Definition 5. Types and features of materials

The term “relining” means renewing one layer of 1) Hard and soft materials
the basal surface of the denture with new base Materials used for relining can be divided into
material in cases in which the mandibular posi- two types (hard and soft). Hard materials are
tion and the occlusal relationship are correctly made of acryl, while soft materials are made of
retained, but the basal surface fitness has dete- acryl, silicone, polyolefin, etc. Because the com-
riorated. position and physical and mechanical properties
differ even among materials of the same type,6,7
it is essential to know the features and charac-
teristics of individual materials well and to select
4. Classification the optimal material for a given case.
Relining can be divided into direct relining (re-
lining with border molding in the mouth) and Q. W hat criteria are used to select between
indirect relining (relining with the taking of a hard and soft materials?
dynamic impression and subsequent processing Recommendation
on the denture in the laboratory). Hard materials are usually selected. Soft materi-
als are selected for cases in which stress-breaking
Q. Criteria used for selecting direct versus is needed. (grade b)
indirect methods
Recommendation Among soft materials, acryl-based materials
The direct method is advisable for cases in which are characterized by high viscoelasticity, while
the denture cannot be deposited, cases in which materials made of silicone or polyolefin are char-
stimulation of the mucosa overlying the residual acterized by high elasticity. Materials made of
ridge is unlikely to occur, and cases in which a silicone undergo less change in physical proper-
certain thickness can be ensured and the occlusal ties over time and exhibit high durability. Mate-
vertical dimension is unlikely to be changed. The rials made of acryl, on the other hand, undergo
indirect method is advisable for cases in which changes in muco-elasticity over time, gradually
the denture can be deposited. (grade c) lowering stress-breaking effects.8-11

The direct method is often used since it does 2) Materials of different polymerization types
not necessitate deposition of the denture and can The types of polymerization of the materials
be implemented at the dental office, although it used for relining and rebasing include the auto-
involves the risk of stimulation due to monomers polymerizing type, light-polymerizing type, heat-
and heat generated from polymerization.1-3 When polymerizing type, and so on. Materials of the
relining is performed using the direct method, autopolymerizing type and light-polymerizing
particularly when soft materials, which need type are used for the direct method, while mate-
adequate thickness are used,4 the basal surface rials of the heat-polymerizing type, autopolymer-
of the denture needs to be trimmed to an extent izing and light-polymerizing types are employed
corresponding to the thickness of the relining for the indirect method.
material. It is sometimes difficult to ensure the If a light-polymerizing material is used, po-
required thickness or to avoid a change in occlu- lymerization and hardening take place after
sal vertical dimension due to the necessity of en- the liquid (monomer) is mixed with the powder
suring adequate thickness. The indirect method (polymer). Once this type of material enters the
has advantages over the direct method in that an residual ridge or a tooth undercuts and hardens
appropriate thickness can be ensured more eas- there, it is sometimes difficult to extract. There-
ily, and the adhesion is stronger due to the lack fore, care is needed to ensure that the material
of exposure to saliva.5 Furthermore, the use of a is taken out before it hardens if it is used for par-
relining jig allows the procedure to be completed tial dentures.
within several hours with the indirect method, Materials of the light-polymerizing type be-
leading to a shorter period during which the den- come polymerized and harden when irradiated.
ture needs to be deposited. For this type of material, several cycles of appli-
cation and removal are possible, allowing the ex-

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 Shiga et al., Prosthodont Res Pract 6 : 209-216, 2007

Are the mandibular position and

occlusal relationship correct?

Yes No

Is improvement seen
after adjustment?

Yes No

Is inadequate strength or discoloration A new denture is fabricated

seen in the base?

Yes No

Is the base thick?

Yes No

Rebasing Is the mucosa hypersensitive?

Yes No

Relining Relining (direct method using Relining (direct or indirect method

(indirect method) light-polymerizing materials) using autopolymerizing materials)

Fig. 1 Examinations and indications

cessive part to be eliminated. Furthermore, since Q. W

 hat examination is needed prior to re-
this type of material is less likely to stimulate lining?
the mucosa,12 it can be used even for patients Recommendation
with hypersensitive mucosa. The optimal method for a given case is selected by
When materials of the heat-polymerizing type performing the examinations for relining, shown
are used, the denture is placed in a flask, which in Figure 1. (grade c)
is then filled with the denture base material to
induce heat-polymerization. This type of material 1) Checking the fit between denture and
is more durable than the other types,13 but has mucosa
drawbacks such as being complicated and time- The fit of the basal surface of the denture to the
consuming. Because of these features and the mucosa overlying residual ridge is checked using
errors usually involved in polymerization, mate- fitness test materials. In addition, retention and
rials of the autopolymerizing type or the light- stability of the denture within the oral cavity are
polymerizing type are often used clinically. tested.
In cases in which the denture is fit to the
mucosa but tends to become detached from the
mucosa during occlusion or cases in which pain
6. Examinations and tests is noted in the mucosa, the mandibular posi-
If poor fitness of the denture is suspected, wheth- tion and occlusal relationship are checked, and
er or not a given patient should be indicated for whether or not the abnormality is improved by
relining is assessed. occlusal adjustment or tissue treatment is exam-
ined.

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 Guideline for Denture Relining

2) Checking the occlusal relationship mucosa to be trimmed is increased or a spillway

including mandibular position is created as needed. Care must be exercised to
Whether the occlusal relationship involving man- avoid excessive trimming of the mucosa since the
dibular position, occlusal vertical dimension is strength of the denture usually decreases as the
appropriate or not, is checked. If a minor problem resin base becomes thinner.14
is found in the mandibular position or occlusion,
whether or not the problem is improved following 1) The direct method
occlusal adjustment or reformation of the occlu- After one layer of the basal surface of the denture
sal surface is tested. Relining is indicated only in is trimmed and a fresh resin surface is exposed,
cases in which the problem is improved following the surface is coated with adhesive and the fol-
such adjustments. lowing procedures are performed:

3) Checking alveolar ridge mucosa (1) Procedure using a autopolymerizing resin

The mucosa overlying the residual ridge is (a) Relining material is mixed; once their fluid-
checked. If any abnormality is found in the mu- ity decreases and it has a cream-like consis-
cosa, tissue conditioning is performed prior to tency, the entire basal surface of the denture
relining. is built up evenly. Once the relining material
changes from a liquid-look to a satiny fin-
ish, the mixture is inserted into the patient’s
mouth.
7. Indications (b) The patient bites down lightly in the inter-
Q. What are the indications for relining? cuspal position and then border molding is
Recommendations done.
Relining is indicated in cases in which the man- (c) Once the resin is somewhat stiffer than a
dibular position and occlusal relationship are putty-like consistency, the denture is taken
appropriate but the fit of the denture base to the out of the patient’s mouth and excess resin
mucosa is poor. (grade c) is removed. The denture is again seated in
the patient’s mouth, and the dentist waits
Contraindications for the resin to harden. An accelerator may
Relining is contraindicated in cases in which the be used to completely harden the denture
mandibular position or the occlusal relationship outside of the patient’s mouth.
cannot be corrected. The direct method is contra- (d) After final hardening, the denture is taken
indicated in cases in which the mucosa is hyper- out of the patient’s mouth.
sensitive. (e) Adjustments are made to sites needing mor-
phological correction and relief, occlusal ad-
Q. What criteria are used for selection of a justments are made, and polishing is done.
relining method?
Recommendations (2) Procedure using light-polymerizing resin
The direct method is advisable for correction of a (a) Light-polymerizing resin is built up on the
minor lack of perfect fit. To deal with moderate or basal surface of the denture and inserted
more severe lack of fitness of dentures, the indi- into the patient’s mouth.
rect method is advisable. The method using a jig (b) The patient bites down lightly in the inter-
is capable of keeping the occlusal vertical dimen- cuspal position and then border molding is
sion when taking an impression and can shorten done.
the time required for manipulation. (grade c) (c) After excess resin is removed, the same pro-
cedure is done again in the patient’s mouth.
This procedure is repeated while immersing
the denture in warm water and reducing its
8. General procedures for relining viscosity.
(Fig. 2)
(d) Cold water is added to the patient’s mouth
Prior to relining, one layer of the basal surface and the viscosity of the resin is increased;
of the denture needs to be trimmed. In cases the dentist removes the denture carefully to
with flabby gums or bone tonus, the amount of keep from deforming its shape.

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 Shiga et al., Prosthodont Res Pract 6 : 209-216, 2007

(e) The entire surface of the light-polymerizing curing: 1 hr at 2 atm, 20 min. at 4 atm, and
resin is coated with air-blocking agent and so forth).
polymerized with a light-curing unit. (j) Adjustments are made to sites needing mor-
(f) The air-blocking agent is rinsed off with phological correction and relief, and polish-
running water. ing is done.
(g) Adjustments are made to sites needing mor-
phological correction and relief, occlusal ad- (2) Use of flask
justments are made, and polishing is done. (a) After boxing, plaster is poured onto the im-
pression surface and a cast is made.
For removable partial dentures, the rest is ad- (b) Excess impression material at the margins
justed to match the rest seat. The denture is held is removed and corrections are made with
in placed by finger pressure so that it is seated in wax.
a specific position in the patient’s mouth and bor- (c) After the ground surface of the denture base
der molding is done. When autopolymerizing res- is coated with a plaster separator, the den-
in is used, resin enters the undercut area of the ture is placed in a flask.
tooth or residual ridge and hardens; the denture (d) The two halves of the flask are separated
may dislodge, so the denture must be removed and impression material on the basal sur-
from the patient’s mouth several times until the face of the denture is removed.
resin hardens. (e) Tin foil or sheet wax is affixed to flabby
gums or bone tonus, and a relief is made.
2) The indirect method (f) The cast is coated with a resin separator.
After one layer of basal surface of the denture is (g) One layer of the basal surface of the den-
trimmed, an impression is taken with a highly ture is removed, a fresh surface is exposed,
fluid precision impression material using the and this is coated with a resin primer, after
denture base as a tray or an impression is taken which autopolymerizing resin is built up.
with a tissue conditioner or dynamic impression (h) The upper and lower halves of the flask are
material. After the patient’s occlusion is checked combined, excess resin is removed, and the
with a check bite, the following procedures are dentist waits for the resin to harden (once
performed: curing is complete, dentures are remounted
on an articulator and occlusal adjustments
(1) Use of relining-jig are made).
(a) After boxing, plaster is poured onto the im- (i) Adjustments are made to sites needing mor-
pression surface and a cast is made. phological correction and relief, and polish-
(b) Plaster is built up on the bottom of the relin- ing is done.
ing-jig, the denture is placed on top, and a
core for the occlusal surface is made. The terms used in this guideline are derived
(c) The top of the jig is assembled, plaster is from the Glossary of Prosthodontic Terms, Sec-
built up at the bottom of the cast, and the ond Edition (edited by the Japan Prosthodontic
base is attached to the top of the jig. Society).
(d) The jig is separated and impression material
on the tissue surface of the denture base is
removed.
(e) Tin foil or sheet wax is affixed to flabby References
gums or bone tonus and a relief is made. 1. Kawaguchi M, Takahashi Y, Miyazaki K et al.
(f) The cast at the top of the jig is coated with a Leaching of residual monomers from chemically-
resin separator. activated direct relining materials. J J Dent Mater
17: 304-308, 1988.
(g) One layer of the basal surface of the denture
2. Bunch J, Johnson GH, Brudvik JS. Evaluation
is trimmed, a fresh resin surface is exposed,
of hard direct reline resins. J Prosthet Dent 57:
and this is coated with a resin primer, after 512-680, 1987.
which autopolymerizing resin is built up. 3. Naka S, Takeuchi T, Takahashi Y et al. Studies on
(h) The top of the jig is joined to the bottom and self-curing resins part 2 on polymerizing tempera-
fixed, and excess resin is removed. ture of reline materials. J Fukuoka Dent Coll 17:
(i) Resin polymerizing is done (e.g. pressure 45-52, 1990.

214
 Guideline for Denture Relining

4. Kazanji MNM, Watkinson AC. Influence of thick- and detachment strength. Nihon Univ Dent J 78:
ness, boxing, and storage on the softness of resil- 27-35 2004.
ient denture lining materials. J Prosthet Dent 59: 10. Kanie T, Terao T, Arikawa H et al. Deterioration of
677-680, 1988. the soft lining materials with the denture cleans-
5. Yasukawa H. Factors affecting bond strength of ers. J Jpn Prosthodont Soc 36: 488-495, 1992.
the relining materials to the denture base resin. 11. Kiat-Amnuay S, Gettleman L, Mekayarajjanan-
Tsurumi Univ Dent J 21: 73-90, 1995. onth T et al. The influence of water storage on
6. Arima T, Murata H, Hamada T. Analysis of com- durometer hardness of 5 soft denture liners over
position and structure of hard autopolymerizing time. J Prosthodont 14: 19-24, 2005.
reline resins. J Oral Rehabili 23: 346-352, 1996. 12. Matsuo E, Toyoda M, Arai T et al. Clinical data of
7. Ochiai K, Takamata T. A physical and mechanical a new light cure type relining material. J Kana-
properties of soft lining materials, Initial value. J gawa Odont Soc 29: 133-138, 1994.
Jpn Prosthodont Soc 38: 383-390, 1994. 13. Arima T, Murata H, Hamada T. Properties of
8. Wright PS. Observations on long-term use of a highly cross-linked autopolymerizing reline acrylic
soft-lining material for mandibular complete den- resins. J Prosthet Dent 73: 55-59, 1995.
tures. J Prosthet Dent 72: 385-392, 1994. 14. Takahashi Y, Kawaguchi M, Chai J. Flexural
9. Sakamura M. A study on chronological changes of strength at the proportional limit of a denture
physical properties of silicone rubber liners to den- base material relined with four different denture
ture base, Influences of cleaning methods on sur- reline materials. Int J Prosthodont 10: 508-512,
face roughness, weight changes, shore hardness, 1997.

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 Shiga et al., Prosthodont Res Pract 6 : 209-216, 2007

Upper complete denture

with an ill-fitting base

Removal of one layer of base Removal of one layer of base Removal of one layer of base

Coating with adhesive Impression using denture Impression using denture

Boxing Boxing

Border molding using

reline material
Making of a plaster cast Making of a plaster cast

Removal of excess impression material

Morphological corrections Making of the core for and corrections with wax
and polishing the occlusal surface

Pouring plaster on the cast and

attaching to the top of the jig Investing in flask

Coating with a resin separator

Separation of flask and removal

Removal of one layer of of one layer of base
base and resin packing

Fixing of the jig, removal of excess

resin, and polymerizing Resin packing and polymerizing

Correction of margins and polishing Correction of margins and polishing

Direct method Indirect method using a jig Indirect method using flasking
Fig. 2 General procedures for relining

216