Report on Prosthodontics about Full Dentures

1. THE EFFECTS OF CLINICAL WEAR ON THE INCIDENCE OF TEMPOROMANDIBULAR
DISORDERS AMONG PATIENTS WITH COMPLETE DENTURES
KHALID A. ARAFA, PHD
JOSEPH RUSSELL N. GORDA

2. INTRODUCTION

3. TEXT
INTRODUCTION
▸ A complete denture is considered insufficient
▸ if there is a lack of stability,
▸ if it has poor retention or
▸ if there is a loss of vertical dimension
▸ result of inaccurate fabrication or
▸ of artificial teeth wear

4. HOW LONG DO DENTURES
USUALLY LAST?
Dentures should last a minimum of
five to seven years. After seven
years, the dentures may need to be
relined or rebased if they become
loose. If the dentures become too
ill-fitting, they will need to be
remade.

5. TEXT
INTRODUCTION
▸ Clinical wear of denture teeth is usually expected in
patients after years of denture use.
▸ Posterior teeth seem to be more affected by food
abrasion.
▸ Development of facets in the anterior teeth due to
attrition (tooth to tooth contact) usually occurs.

6. TEXT
INTRODUCTION
▸ A positive relationship has been found between the
duration of complete denture wearing and the
incidence of temporomandibular disorder (TMD).
▸ The patients wearing complete dentures could be
subjected to unbalanced distribution of occlusal force
as a result of clinical wear of dentures.

7. TEXT
INTRODUCTION
▸ After five years of use, approximately half of complete
denture patients require replacement. Extensive wear
of denture teeth could affect the patient’s quality of
life through harmful impact on the masticatory system

8. TEXT
INTRODUCTION
▸ Denture teeth made of acrylic resin usually show progressive
occlusal wear, which could lead to rapid loss of vertical dimension.
▸ Three types of wear have been suggested:
▸ frictional wear,
▸ adhesive wear and
▸ abrasive wear

9. TEXT
INTRODUCTION
▸ In vitro studies aiming to measure wear of denture
teeth have the drawback of assessing abrasive wear
only under a few conditions, while clinical trials could
yield more comprehensive assessment.

10. TEXT
INTRODUCTION
▸ Artificial teeth are commonly made from two types of
material: acrylic resin and porcelain. Porcelain is well
known for its stability against wear and resistance
against abrasive forces. Denture teeth made of
porcelain can act as a control for acrylic resin teeth
because they are highly resistant to abrasive forces
and are considered to be more stable against wear.

11. TEXT
PORCELAIN VS. ACRYLIC TEETH
▸ Advantages of porcelain teeth
▸ slightly greater translucency and depth of color
▸ Harder than acrylic - more durable.
▸ Resist wear - this preserves the normal jaw movements and alignment for a
longer period.
▸ Resist staining
▸ Because porcelain teeth do not bond chemically to the base, they are easily
removed from the base for rebasing.

12. TEXT
▸ Disadvantages of porcelain teeth
▸ Noisy: clicking sounds are made when porcelain teeth comes into occlusion with another
porcelain tooth
▸ Brittle – more likely to fracture than acrylic teeth
▸ Do not bond chemically to denture base – attachment is achieved my means of mechanical
bonding. Small holes or metal pins are incorporated in the base of porcelain teeth during their
production to enable mechanical bonding to the denture base.
▸Not as compatible as acrylic teeth with the base of the denture – There is a serious mismatch in
coefficient of thermal expansion and modulus of elasticity between porcelain and acrylic resin.
This may lead to crazing and cracking of the denture base in the region around the base of the
porcelain teeth.

13. TEXT
▸ Its density value is about twice that of acrylic teeth; dentures constructed with porcelain teeth
are much heavier.
▸ Difficult to fabricate
▸ Difficult to trim, due to the hardness of this material
▸ Porcelain teeth exert more force to the underlying supporting soft tissues, causing more
trauma to these tissues. This is a function of the greater modulus of elasticity of porcelain.
This trauma is capable of accelerating the rate by which the underlying bone resorbs.
▸ If a denture is going to be worn against opposing natural teeth than plastic teeth should be
selected because porcelain teeth, being harder, could excessively wear natural teeth away

14. TEXT
▸ Advantages of acrylic teeth
▸ Easy to adjust and trim
▸ Chemical bonding to denture base, as they are made of the same material
▸ Acrylic teeth are more compatible with the denture base than porcelain teeth. no clicking sound
▸ Easy to fabricate
▸ Less trauma to denture-bearing area. This is particularly crucial for people with implants
supporting the fake tooth. If they have lost bone or gum tissues around the implant, acrylic teeth
are more forgiving when you grind your teeth, and will hold their position longer than porcelain
teeth.
▸ Dentures made with acrylic teeth are lighter.

15. TEXT
▸ Disadvantages of acrylic teeth
▸ Acrylic teeth are susceptible to abrasion, e.g. if the patient has a habit of
teeth-grinding (bruxism) or eats abrasive diets, the teeth will wear down with
time, causing changes in the length of the teeth.
▸ Easily stained, as they contain microscopic pits that can hold bacteria
▸ In rebasing, difficult to remove acrylic teeth from the denture base

17. OBJECTIVE

18. TEXT
OBJECTIVE
▸ This study evaluates the effect of clinical wear
on the incidence of temporomandibular
disorders in patients with complete dentures.

19. METHOD

20. TEXT
METHOD
▸ A randomized clinical trial was conducted on two groups;
▸ group 1 (30 patients) received complete upper and
lower dentures with teeth made of heat-cured acrylic
resin,
▸ and group 2 (29 patients) received complete upper and
lower dentures with teeth fabricated of porcelain.

21. TEXT
METHOD
▸ The occurrence and clinical examination of
temporomandibular disorders were evaluated using
▸ Helkimo anamnestic dysfunction index (Ai) and
▸ Helkimo clinical dysfunction index (Di),
respectively.

22. TEXT
METHOD
▸ Clinical wear of denture teeth was estimated by the
assessment of wear depth using the mean differences
between tracing images of lingual cusps at each follow-up.
▸ The patients were followed up at 6, 12, 18 and 24 months
for assessment of clinical wear and incidence of
temporomandibular disorders.

23. RESULTS

25. TEXT
RESULTS
▸ The acrylic resin group was subjected to significantly
higher wear than the porcelain group at 12, 18 and 24
months of follow-up.

27. TEXT
RESULTS
▸ The incidence of temporomandibular disorders was
also significantly higher in the acrylic resin group than
in the porcelain group at 18 and 24 months of follow-
up.

30. CONCLUSION

31. TEXT
CONCLUSION
▸ There was no significant direct association between
clinical wear and incidence of TMD among complete
denture patients.
▸ There was a higher incidence of TMD among patients
wearing complete dentures with artificial teeth made of
acrylic resin in comparison with those wearing complete
dentures with teeth made of porcelain.

32. TEXT
CONCLUSION
▸ The clinical wear affecting acrylic resin teeth was
significantly higher than that affecting artificial teeth
made of porcelain.
▸ Additionally, patients with a preferred chewing side
were subjected to higher incidence of TMD.