This presentation includes various causes of denture fracture and factors affecting the strength of denture repair.

1. Seo.RS, Neppelenbroek.K, Filho.J. J
Prosthet Dent 2007;16:302-310
PRESENTED BY:
Dr. Sabnoor Aujla
M.D.S First Year
MMCDSR, Mullana.

2. REPAIR MATERIALS
SURFACE DESIGNS
MECHANICAL ; and
CHEMICAL TREATMENTS
STRONGER REPAIR

3. CAUSES
INSIDE THE MOUTH
Poor Fit
Poorly balanced
occlusion
Faulty design and
Fabrication
Insufficient strength of the repair
material
Continuous Stress after years in
clinical use
OUTSIDE THE MOUTH
IMPACTS AND ACCIDENTS

4. In the survey, 20 labs denture construction and repair was studied and co-laborated the
results showing the ratio of maxillary to mandibular denture fracture is 2:1 and being the
most common cause :
POOR FIT and IMBALANCE OCCLUSION .
Author further described the:
STRESS DISTRIBUATION by the PHOTOELASTIC STRESS ANALYSIS which indicated that
:
Maximum COMPRESSIVE STRESS – base adjacent to the supporting tissues
TENSILE STRESS – elsewhere in CENTIC OCCLUSION
Least Stress: midline and
Maximum Stress –anterio posterior ridge in centric occlusion
But in the cases like- Improper balance occlusal -Faulty design ;or -The Teeth wear with time,
the stress distribution changes:
Maximum TENSILE STRESS : Anterior labial region and the region lingual to the incisors
& THE INCISAL NOTCH
Stress Raiser (crack initiation point)
MIDLINE FRACTURE
: Any factor that alters stress distribution leads to the fracture
: The Incisal Notch is being referred as the most important causative factor in
the Midline Fracture
An Analysis of causes of fracture acrylic resin dentures.
Beyli MS, von FraunhoferJA. J Prosthet Dent 1981;46:238-241

5. TO OBTAIN A REPAIR THAT IS EQAUL OR GREATER IN
STRENGTH THAN THE ORIGINAL MATERIAL.

6. Factors influencing strength of
acrylic denture repairs
Effect of REPAIR MATERIAL
Effect of REINFORCEMENT
Effect of WATER STORAGE
Effect of POST POLYMERIZATION TREATMENT
Effect of SURFACE TREATMENT

7. The choice of material depends on the Working Time, the
Strength to be obtained and the degree of Dimensional stability
after the repair.
Auto
polymerizing
acrylic resin
Heat
polymerized
acrylic resin
Visible light
polymerized
acrylic resin
Microwave
polymerized
acrylic resin

8. Auto polymerizing acrylic resin
Simple and Quick repair
Disadvantage : Recurrent fracture
Insufficient transverse strength
60-65% of the original strength of
the denture
Heat polymerized acrylic resin
Better transverse strength
70%-80% of the original bulk material
Disadvantage: seldom performed
Extended polymerization time and
patient go without denture during the
lab procedures.
Visible light polymerized
acrylic resin
Good colour stability
Good physicomechanical properties
Disadvantage:Poor adhesion to teeth
Increase brittleness
Reduces the Impact resistance
Microwave polymerized acrylic
resin
93-103% of the original acrylic resin.
Superior Physical Properties & Transverse
strength
High impact resistance than autopoly.
Little literature is available on the use of
microwave system for repairs

9. Repair of denture base resins with visible light-polymerized
reline material: Effect on tensile and shear bond strengths.
Stipho H, Talic Y. J Prosthet Dent 2001;86:143-8
This study measured the tensile & shear bond strengths of Traid VLP, PMMA, glass fiber
reinforced PMMA acrylic resins before & after repair with Triad VLP repair material.
PURPOSE:
56 specimens were fabricated . Both triad VLP & autopolymerising acrylic resins were
used to repair identical laboratory fabricated resin joints.28 specimens in 4 different
groups of 7 each were prepared. The specimens were tested at a constant rate in a
universal testing machine and results were analysed
-The VLP reline material produced the highest bond strengths with
the Triad VLP resin but was less favourable when used to repair
the PMMA and GF-PMMA acrylic resins.
-The VLP reline material produced low after-repair tensile and
shear bond strength when used with the auto polymerised resin
METHOD:
RESULT & CONCLUSION

10. REPAIR OF DENTURE RESINS USING VISIBLE LIGHT-CURED
MATERIALS
Andreopoulos AG, Polyzois GL. J Prosthet Dent 1994;72:462-468
•Specimens were repaired with atopolymerising and visible light cured repaired
material.
•Flexural properties were measured and revealed that the
highest strength and toughness of the joint are obtained by the
autopolymerising repair material and are independent on the base of the resin.
•The VLC exhibited a lower repair strength(22%-58%) and toughness (9%-
33%)
•No interaction is seen between the base and repair material, which was
attributed to poor bonding created at the interface

11. REPAIR STRENGTH OF AUTOPOLYMERIZING, MICROWAVE, AND
CONVENTIONAL HEAT POLYMERIZED ACYLIC RESINS.
Rached RN, Powers JM, Del Bel Curry AA. J Prosthet Dent 2004;92:79-82
This study evaluates the transverse repair strength of a conventional heat-polymerized and a
microwave-polymerized acrylic resin that were repaired with these same resins and with an auto
polymerizing acrylic resin.
24 rectangular specimens of heat-polymerized or microwave polymerized acrylic resin and 6
autopolymerising acrylic resin were manufactured according to the specifications .18 specimens
were selected randomly. 6 of each material remained intact(control), each 6 were sectioned to
create a 10mm gap and repaired with the same materials.
After an additional 7 days of storage, the transverse strength of the repaired and intact specimens
was measured
The intact and repaired specimens showed similar transverse strength values, except for
microwave polymerized resin which was stronger. No differences were detected among the
repaired groups
1) The intact microwave-polymerized material exhibited superior transverse strength.
2) The autopolymerised resin exhibited repair strength comparable to heat and
microwave-poly.
3) The repair methods exhibited a low incidence of failure at the interface.
PURPOSE:
METHOD:
RESULT:
CONCLUSION:

12. Metal
Wires
Nylons Carbon
fibres
Glass
fibres
Aramid
fibres
High Modulus
Polythene
Titanium

13. Silanization is the covering of a surface through self-assembly with
alkoxysilane molecules.
Mineral components like Mica, glass and metal oxide surfaces can all be
silanized, because they contain hydroxyl groups which attack and displace
the alkoxy groups on the silane
Sandblasting is a general term used to describe the act of propelling very
fine bits of material at high-velocity to clean or etch a surface.
.
Enhances the retention between strengthener and the resin by increasing
surface area to promote adhesion.
ADDITIONAL TEACHNIQUES :
SILANIZATION SANDBLASTING

14. Reinforcement of maxillary denture with silane-treated ultra high modulus
polyethylene fibres.
Karacaer O, Dogan OM, Tincer T, et al. J Oral Sci 2001;43:103-107
CLINICAL STUDY
• Maxillary denture of a patient with the history of midline fracture.
• The broken denture was reinforced with the ultra high modulus
polyethylene fibres in woven form.
• Those fibres was treated with a silane-coupling agent
• And, sandwiched between acrylic dough.
All the dentures were satisfactory and did not exhibited any signs
of recurrent fracture
The authors observed – at the end of 18 months

15. •TIME DEPENDENT
•Weak one hour after lab procedures
•Mechanical properties of the repaired
specimens reach optimum strength after 1 day
to 1 week of water immersion.
•Shear bond strength of visible light-
polymerized resin to denture base resin
significantly increase after 48 hours of
immersion in water

16. SURFACE TREATMENT
(Adds onto the strength)

17. SURFACE TREATMENT
CHEMICALLY MECHANICALLY
BOND
STRENGTH
ADHESION
WEAK JUNCTION
(between new and parent material)

18. Mechanical
Treatment
AIM: To increase the contact area
Various surface modifications
(joint surfaces)
Chemical
Treatment
AIM: To promote adhesion(roughness)
Wetting the parent surface with various
chemicals
(monomer, acetone , chloride etc)

19. BUTT JOINT
BEVEL JOINT
ROUNDED
RABBET JOINT
78.5mm
50mm
72.5mm

20. REPAIR WIDTH
• Range from 1.5 to 3 mm
• If less – improper retentive feature
• If more- weakens the contact area

21. THE EFFECT OF JOINT SURFACE CONTOURS ON THE
TRANSVERSE STRENGTH OF REPAIRED ACRYLIC RESIN.
Harrison WM, Stransbury BE. J Prosthet Dent 1970;23:464-472
To investigate what effect the configuration of the joint interface surfaces had on the
transverse strength of repaired acrylic resin.
After the test specimens were prepared according to the specifications, they were
fracture under the transverse load .
The joint surface interface were prepared either as BUTT JOINT, ROUNDED JOINT OR
RABBETED JOINT.
Out of 45, 16 were prepared with rabbeted joint , 15 with butt and 14 with rounded
After the statistical analysis:
6.3% rabbeted joint, 20% of the butt joint and 57% of the rounded joint
Could be considered as properly made since the fracture line did not occur along the joint interface
surfaces
Mean of the rounded joint was significantly different from the mean of the rabbeted and butt joint.
Clearly indicated rounded joint was superior to the rest of the joints.
PURPOSE:
METHOD:
RESULT:
CONCLUSION:

22. WETTING THE SURFACE
MONOMER – 180SECONDS – formation of new polymer chain
CHOLOROFRM- 5SEC- CLEARNER SITE
ACETONE – 30seconds
METHYLENE CHLORIDE- 5SEC- CRAZAING &
NUMEROUS PITS – 2MICOMETER IN DIATEMER.
IT HAS ALSO FOUND TO INCREASE THE
TRANSVERSE STRENGTH BY 12percemt
Cross-linkage of polymer chains begins, which will only swell in solvents
like chloroform and acetone

23. Repair of denture base resin using woven metal and glass
fiber: Effect of methylene chloride pre-treatment.
Nagai E, Otani K, Satoh Y et al. J Prosthet Dent 2001;85:496-500
This study evaluated the strength & modulus of elasticity of repaired acrylic specimens
reinforced with various processes.
MATERIALS AND METHODS:
Auto polymerizing resin was used with woven metal fibber & glass fiber with &
without methylene chloride pre-treatment. Specimens were cut to obtain
space for placing repair resin. All the specimens were stored in 37°C distilled
water for 48hrs before the test. Data were statistically analysed.
PURPOSE
RESULTS:
Specimens repaired by glass fiber with methylene chloride pre-treatment
exhibited higher transverse strength & greater modulus of elasticity.
CONCLUSION:
Reinforcement with glass fiber and methylene chloride surface treatment
produced transverse strength and a modulus of elasticity higher than control.

25. MIDLINE FRACTURE

26. REPAIR OF ANY BOKEN PART

27. MISSING PART FRACTURE REPAIR

28. TOOTH FRACTURE REPAIR

30. 1) An Analysis of causes of fracture acrylic resin dentures.
Beyli MS, von FraunhoferJA. J Prosthet Dent 1981;46:238-241
REFERENCES :
2) Reinforcement of maxillary denture with silane-treated ultra high modulus
polyethylene fibres.
Karacaer O, Dogan OM, Tincer T, et al. J Oral Sci 2001;43:103-107
3) Repair of denture base resin using woven metal and glass fiber: Effect of
methylene chloride pre-treatment.
Nagai E, Otani K, Satoh Y et al. J Prosthet Dent 2001;85:496-500
4) Repair of denture base resins with visible light-polymerized reline material:
Effect on tensile and shear bond strengths.
Stipho H, Talic Y. J Prosthet Dent 2001;86:143-8
5) REPAIR STRENGTH OF AUTOPOLYMERIZING, MICROWAVE, AND CONVENTIONAL HEAT
POLYMERIZED ACYLIC RESINS.
Rached RN, Powers JM, Del Bel Curry AA. J Prosthet Dent 2004;92:79-82
6) THE EFFECT OF JOINT SURFACE CONTOURS ON THE TRANSVERSE STRENGTH OF
REPAIRED ACRYLIC RESIN.
Harrison WM, Stransbury BE. J Prosthet Dent 1970;23:464-472

31. 8) REPAIR TECHNIQUE FOR CRACKED DENTURES
Donald E, Lewis. J Prosthet Dent 1980;44:582-583
9) REPAIR OF DENTURE RESINS USING VISIBLE LIGHT-CURED MATERIALS
Andreopoulos AG, Polyzois GL. J Prosthet Dent 1994;72:462-468
7) Morrow Rudd Rhoads: Dental Laboratory procedures
complete denture.