1. INTRODUCTION

2. A comparison of the effect of different
occlusal forms in mandibular implant
overdentures
Mohamed Moataz et.al .
University of Pittsburgh Medical Center, Pittsburgh
Journal of Prosthetic Dentistry1 998;79:422-9

3. STATEMENT OF PROBLEM
Posterior tooth form selection for implant overdentures
is made according to personal preference and
experience using the concepts of conventional
complete denture Prosthodontics.

4. PURPOSE.
(1) Compared the masticatory efficiency of three
occlusal forms, 0 degrees, 30 degrees, and lingual
contact (lingualized occlusion), in subjects with
mandibular implant overdentures,
(2) Determined their effects on the implant supporting
tissues.

5. MATERIAL AND METHODS
INCLUSION CRITERIA
1. Eight edentulous subjects, four men and four women,
ages 52 to 78 years.
2. Skeletal class I jaw relationships.
3. Four root form endosseous-type implants (Nobel
Biocare, Göteborg, Sweden) in the mandibular
symphysis area that had been restored with Hader bar
retained implant overdentures and that had been in
function for at least 1 year before the study.

6. For each patient, a mandibular implant overdenture and a
maxillary conventional complete denture were constructed
both with interchangeable posterior occlusal segments.
(A posterior occlusal form was randomly selected for
each patient)

7. A, Maxillary and mandibular anterior teeth were set according to esthetics and
phonetics and were not changed throughout study.
B, Cross-section of maxillary and mandibular bases before attaching
different posterior
tooth forms.
C, Zero degree posterior teeth attached to denture bases.
D, Lingualized posterior occlusion. Maxillary lingual cusps of posterior teeth
touch
central fossa of mandibular teeth.
E, Use of 30 degree posterior segments

9. Patients used each occlusal form for 6 months during which
time three test sessions were performed at 2- month
intervals.
IN EACH TEST SESSION, PATIENTS’ MASTICATORY
EFFICIENCY WAS EVALUATED AND PERI-IMPLANT
MUCOSA AND BONE ASSESSED CLINICALLY AND
RADIOGRAPHICALLY.
Masticatory efficiency was evaluated through five measures
recorded while patients were chewing standardized pieces
(1 cm cubes) of test foods in normal manner.

10. The test foods used were bread, hard cheese, beef sausage,
raw carrots, and apples.
Patients were seated in an upright position and were
instructed to chew at a normal rate and swallow.
Four trials (four cubes) were made for each test food.

11. While chewing the food specimens, five measurements
were recorded:
a) The number of chewing strokes up to the first
swallow.
b) The number of chewing strokes until the mouth was
free of food.
c) The number of swallows until the mouth was free of
food.
d) The time (in seconds) elapsed until the first
swallow.
e) The time (in seconds) until the mouth was free of food.
(two persons who remained the same ,One recorded the number of
chewing strokes and swallows, and the other recorded the time.)

12. Patients’ chewing preferences were assessed with a
standardized questionnaire administered to patients
once every 6 months at the end of use for each posterior
occlusal form.
(The questionnaire evaluated the patients’ opinion concerning
comfort during rest and chewing, stability, speech, ease of
cleaning, and appearance (esthetics) of their dentures.)

13. CLINICAL EVALUATION OF THE PERI-IMPLANT TISSUES
1. Plaque Index.
2. Gingival Index.
3. Mobility .
4. Probing Depth.
5. Measurement Of The Epithelial Attachment Level.
6. Changes in bone level around the necks of implants
was assessed with standardized periapical radiographs
with a superimposed grid.
7. Bone density along the length of the implants
was also
determinedanddetect minor bone changes. forms were
(The second to third randomly selected occlusal
similarly tested every 2 months for 6 months.)

14. STATISTICAL ANALYSES
1. The mean chewing efficiency and clinical and
radiographic differences between the occlusal forms
were evaluated by a repeated measures analysis of
variance (MANOVA).
2. Repeated measures analysis of variance (ANOVA) was
used to analyze self-report questionnaire data.
All analyses were computed with the SYSTAT
(Version 7)
p value of < 0.05 was considered to be
statistically significant

15. RESULTS
OCCLUSAL FORM MEAN ANALYSES

17. PATIENTS SUBJECTIVE OCCLUSAL FORM RATING
57.14% of patients preferred
the 30 degree occlusal form
42.86% preferred the
lingualized occlusal form.
None of the patients selected
the 0 degree occlusal form

18. RADIOGRAPHIC FINDINGS

19. CLINICAL FINDINGS

20. DISCUSSION
The primary results of this study showed that 30 degree
and lingualized occlusal forms provide better chewing
efficiency than 0 degree occlusal form in implant
overdentures.
The use of implants to stabilize and retain mandibular
dentures therefore improved denture retention and
stability closer to natural dentition than the removable
denture condition.

21. The values of the chewing efficiency measures also varied
significantly with the type of food used. Patients therefore
chewed and swallowed differently depending on the
hardness and texture of the food.
Validation of methods for the analysis of masticatory
function. J Dent Res 1990;69:334.
Chewing efficiency and state of dentition. A methodologic
study. Acta Odontol Scand 1978;36:33-41.
The influence of food type on experimental design in studies of
chewing efficiency. J Dent Res 1991;70:277.

22. Radiographic assessment of the bone surrounding the
implants did not show any significant difference in height
or density associated with the different occlusal forms
used.
Lingualized and 30 degree occlusal forms had
significantly less gingival index scores compared with the
0 degree occlusal form.

23. CONCLUSIONS
1. The choice of posterior occlusal forms in implant
overdentures should not be based on conventional
complete denture occlusion.
2. The number of chewing strokes up to the first swallow
and until the mouth was free of food provided better
discrimination between the different occlusal forms than
the chewing time and number of swallows.
4. The use of 30 degree and lingualized occlusal forms
provided better chewing efficiency than 0 degree occlusal
form.
NONE OF THE OCCLUSAL FORMS TESTED SHOWED ANY CLINICAL
OR RADIOGRAPHIC DETRIMENTAL CHANGES IN IMPLANT
SUPPORTING TISSUES