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The influence of geometric occlusal carvings on the masticatory effectiveness of complete dentures
THE INFLUENCE MASTICATORY
OF GEOMETRIC EFFECTIVENESS
OCCLUSAL CARVINGS ON THE OF COMPLETE DENTURES
A. ALBERT YURKSTAS, B.S., MS., D.M.D.* Tufts University
School of Dental
Medicine,
Boston, Mass.
ANY WORKERS~-~ have studied the chewing efficiency of complete dentures, and
yet, the literature does not reveal the exact role that the occlusal schemeplays in influencing masticatory effectiveness. Sauser and Yurkstasl pointed out that variations in occlusal surface carvings resulted in differences of masticatory performance when overlays were placed on the natural dentition. They suggested two conclusions: “( 1) masticatory performance was better when both upper and lower occlusal surfaces were provided with markings than when one or both were without markings, and (2) highest masticatory performance resulted from the use of occlusal carvings which ran a longitudinal course along the upper occlusal surface regardless of the character of the lower occlusal scheme.” The situation was far different from that in complete dentures which rest on oral mucosa of varying resiliency. Therefore, their conclusions are not valid for complete dentures. Other studies have dealt with the influence of locked versus balanced occlusions,6 and anatomic versus nonanatomic teeth, but factors such as sluicing, tooth position, number of teeth, etc., have not been investigated thoroughly. The purpose of this study was to evaluate the effect of straight-line geometric occlusal carvings on the masticatory effectiveness of complete dentures with an occlusal schemethat conformed to Sears’ll definition of a nonanatomic occlusion. The evaluation of commercially available posterior tooth forms was omitted purposely in order to evaluate certain basic occlusal factors that might influence complete denture efficiency, rather than to determine the most efficient tooth form for a given number of denture wearers. It is imperative to emphasize that the chewing efficiency of complete dentures is not usually the paramount consideration in evaluating their over-all success.The importance of efficient mastication must be weighed together with factors such as comfort, esthetics, phonetics, and the preservation of associated supporting structures. Each of these factors may assumedifferent degrees of importance, depending upon the techniques used, the purpose of the dentist, and, most important, the requirements of the patient. PROCEDURE
Test dentures were constructed for 20 edentulous patients with a technique *Chairman of the Departmeni
of Complete Dentures. 452
453
Fig. markings. Fig.
l.-The
occlusal
Z.-Selected
surfaces
grooved
on one group
patterns
of test dentures
are block
teeth
with
no occlusal
are used on the test dentures.
experience varyadvocated by Hardy. l2 Ten persons had previous denture-wearing ing from 2 to 17 years, and 10 had no previous denture-wearing experience. The patients varied in age from 30 to 6.5 with a mean age of 48. Block-type posterior teeth were used, in which the two bicuspids and first molar tooth were fabricated as a single unit. They resembled the teeth designed by Hardy’” with the exception of metal inserts. The final test dentures were typical of complete dentures, except that the posterior tooth segments consisted of block teeth (Figs. 1 and 2). The occlusal surfaces of the posterior elements were modified, first, by selected grooved patterns and then by addition of metal inserts. As successive modifications were made in the occlusal surfaces, tests were given to determine their effect upon masticatory efficiency. Four grooved patterns were selected1 for testing (Fig. 3.). They included : (1) no markings on the upper or lower occlusal surface (2) longitudinal upper grooves and no markings on the lower occlusal surface, (3) longitudinal upper grooves and buccolingual lower grooves, and (4) longitudinal upper grooves and longitudinal lower grooves. Henceforth, we will refer to the test patterns by
Upper Pattern
Lower
I II
Pattern
2 Eli
Pattern
3 EuIIl
Pattern
4 EEI
Fig. 3.-Diagrammatic
representation
of the patterns
used on the test dentures,
454
J. Pros. Den. May-June, 1963
YURKSTAS
Fig.
4.
Fig.
Fig. 4.-Longitudinal upper and buccolingual occlusal surfaces of the test dentures. Fig. 5.-Longitudinal upper and lower metal
lower strips
metal
are used
5. strips
are
in one group
inserted of test
into
the
dentures.
these numbers. The selection of the type of pattern to be inscribed on the test dentures and the sequence of presentation were based on random tables by Cochran and Cox.14 This procedure tended to minimize the time and learning variables. Grooves were cut into the occlusal surfaces of the acrylic resin posterior teeth with a mounted stone to produce shearing or cutting edges. The grooves were uniformly 1.0 mm. deep and 1.0 mm. wide. When a change in the occlusal markings was desired, the grooves were filled with a cold-curing resin and placed against a glass slab until the resin cured. This technique preserved the original vertical height and buccolingual contour of the occluding surfaces. Strips of Vitallium* were imbedded later in the occlusal surfaces of the test dentures and secured with an autopolymerizing acrylic resin. Two occlusal configurations that corresponded to Patterns 3 and 4 of the grooved surfaces were used (Figs. 4 and 5). The metal inserts projected 1 mm. above the occlusal surface. Masticatory performance tests with peanuts at 20 strokes were conducted on the right and left sides immediately upon completion of the dentures. No carving was present on the occlusal surfaces at this time. The patients wore the test dentures for a one week adjustment period, and reported daily for necessary modifications (Table I). At the end of one week, a selected occlusal pattern was inscribed on the block teeth. The patient then performed a series of mast&tory tests of 20 strokes each on right and left sides (Table II). The test foods were peanuts, carperformance was computed as rots, and ham in 3 Gm. samples. lp7,15 Masticatory the percentage of food that passed through a given screen opening. The tests were repeated at weekly intervals, and a new occlusal pattern was inscribed on the block teeth each week for 4 weeks. Approximately 3 months after the dentures were delivered, the patients were recalled and all 4 grooved occlusal patterns were tested on the same day. Final tests with the grooved patterns were made 9 months later. The patients had been wearing their dentures for 1 year, plus or minus 3 weeks. At this time, all patients were tested with peanuts and ham on both right and left sides, Metal inserts were then imbedded and the testing was continued for another 3 months. RESirLTS
AND
DISCUSSION
The distribution *Supplied
of some of the experimental
by the Austenal
Co. of New
York
City,
N. Y.
data with
peanuts as a test food
puue; ”
;3
GEOMETRIC
OCCLUSAL
455
CARVINGS
is shown in Fig. 6. Not all patients could chew with equal facility, even though the teeth, the occlusal markings, and the denture technique were identical. The masticatory performance of the left and right sides had approximately the same distribution and showed no significant difference. Similar results were found with ham and carrots as test foods (Fig. 7). The results obtained with the grooved patterns over the 1 year testing period are shown in Fig. 8. The findings led to these observations: (1) At any stage of the experiment, there were no significant differences in masticatory efficiency TABLE
I.
SCHEDULE
OF THE EXPERIMENTAL
TIME AFTER INSERTION
APPT. NO.
APPOINTMENTS
PROCEDURE --__--
__I
0
1-8 1:
i l&Y 4 days
11
12 z”-iZiT
1.3
3 weeks 4 weeks
:I: 16
5 3 12 15
17 ii
weeks months months months
Patients examined and selected Dentures constructed Dentures inserted and unmarked pattern tested Adjustment appointment Adjustment appointment Adjustment appointment. First test pattern inscribed First test pattern tested and removed, second pattern Second test pattern tested and removed, third pattern Third test pattern tested and removed, fourth pattern Fourth test pattern tested All patterns retested Final pattern retested. Inserts imbedded and tested Insert pattern retested
PEANUTS c&s
Fig.
G.-Typical
distribution
of peanut
(Ona Week) PNTERH 0-
masticatory
performance
test
scores.
inscribed inscribed inscribed
456
J. Pros. May-June,
YURKSTAS
Den. 1963
among the 4 grooved patterns tested. (2) Tests made 1 week after inscribing a new pattern failed to show a statistically significant improvement in masticatory performance over the first day it was tested. Little or no learning occured during this 1 week period. ‘(3) At the 3 month interval, there as a definite improvement in masticatory performance, but the improvement over the day of insertion was not great enough to be statistically significant. (4) When the first day scores and the 1 week scores for grooved patterns were compared with the 1 year score, the improvement in masticatory performance was statistically significant. Data on the test results obtained for each patient’s preferred side of chewing with both grooved patterns and metal inserts are seen in Fig. 9 (peanuts) and Fig.
TABLE
II.
MASTICATORY
PERFORMANCE
SCORES:
ALL
PATIENTS
AND
ALL
FOODS
PATTERNSTESTED TEST FOOD
Peanuts
CONDITIONS OF TEST
1st day
------_____ STROKES
R* kS.
22.1 21.1 22.2
21.5 22.4 22.1
z; 27.0
22.8 22.3 22.4
L” P.S.
19.9 20.9 20.9
20.9 22.8 23.9
22.1 24.2 25.1
23.7 23.0 24.7
1 P.S. 2 P.S.
30.7 31.6
29.0 30.8
27.8 31.1
27.6 29.9
L” P.S.
37.8 41.3 40.0
33.7 37.6 36.6
Inserts 1 year
R L P.S.
40.7 44.3 42.5
38.1 39.3 39.7
Inserts 1.5 months
R L P.S.
45.3 54.0 48.3
2:: 48.5
1 week
R
3 months
bS P:S:
6.9 6.4 6.9 11.7
7.0 7.0 7.0 13.9
36.0 36.8 38.5
27.5 28.3 22.5
24.3 28.0 27.5 25.2
25.6
33.0 30.8 29.3
23.0 26.6 27.6
1. week
3 months 1 year
Carrots
Inserts 15 months
Ham
Inserts 1 year
5.3 4.0 4.4 11.7
R L P.S.
1 week 3 months
3.7 5.7 4.8 9.7
L” P.S. P.S. L” P.S.
19.9 18.4 20.5 28.7
21.5 22.0 22.4 27.2
22 28.4
10 (carrots and ham). The results led to these observations: (1) VVhen metal illsert patterns were substituted and tested on the same day of the 1 year test with grooved patterns, no significant difference in masticatory performance was apparent. (2) At the 15 month level, after 3 months’ use of the metal-insert patterns, masticatory performance was substantially better than performance with grooved patterns at the 1 year level. The improvement was statistically significant to the 5 per cent level. Lack of a control group makes it hazardous to attribute this improvement to the metal inserts alone. Over-all evaluation of test results with ham as a test food suggests that it has
PATTERN
Fig.
8.-Masticatory
c3
E
[7
CD!
performance
tests over
a one year
period.
4.58
J. Pros. Den. May-June, 1963
YURKSTAS
55 _ Upper
Lower
ir
- /J=
Pattern
I
on
0
- &j:
Pattern
2
50 Eam EB
“p”- q
=Pattern
3
gi
=Poitarn
4
- fJ
’::
0’
I Doy
:
I Week Grooves
G~OOVSS
Grooves
Grooves
I’I’ II,li;’ Year Inserts
rths lnserrs
Time Fig.
9.-Masticatory
performance
tests
on the preferred
side with
Cl
Pattern
I
IsI
Pottern
2 E
if%?
q PotternE llul Pattern4 M
40
peanuts.
0
lllll R
0 3 Months
Grooves
15 Months
Cmots
I Week
Inserts
Grooves
Months Ham
Grooves
I Year t Horn Inserts
Time Fig.
lO.-Masticatory
performance
tests with
carrots
and ham on the preferred
side.
Volume Number
13 3
GEOMETRIC
OCCLITSAT,
459
CARVINGS
little value in such a study as this. No statistically significant differences could he demonstrated among the test scores for the unmarked patterns, grooved patterns, and metal-insert patterns with this food. Tests made at different time intervals revealed only slight differences of no statistical significance. These findings suggest that foods such as ham offer little difficulty to denture wearers. Experimental results obtained with carrots are quite limited. At the 3 month level no significant differences could be demonstrated among the patterns tested. An experimental error of the use of 20 strokes with the first 2 tests and 40 strokes with the final test was committed. The analysis of these data is omitted. The results did suggest that the value of carrots as a test food should be more fully exploited. When data derived from Patterns 3 and 4 were compared (Figs. 9 and IO), there was lit.tle difference between the two patterns. This suggested the generalization that under these tests conditions differences in geometric patterns inscribed on the occlusal surfaces produced little difference in masticatory performance.
50 _
u 2 E ;; r z 6
45 403530 -
s 25.!! 2 zoz 15 _ IO 5first ciw day week
I
I
I
I
three months
y%
.zr Inserts
fifteen months mssrts
Time Fig.
Il.---Comparison
of the
masticatory
performance
tests
on
the
left
and
right
sides.
The masticatory performance results on the left and right sides of Pattern 4 are shown in Fig. 11. No statistically significant difference existed between the left and right sides. A trend was observed which indicated that complete dentures with occlusal markings on both upper and lower posterior tooth segments were more effective than dentures which had one or both opposing tooth segments free from occlusal markings. Observations also suggested that adequate escapeways for masticated food had an influence on the masticatory effectiveness of a given occlusal surface.
460
YURKSTAS
J. Pros. May-June,
Den. 1963
Although the results of this study did not indicate that these modifications of the occlusal surface greatly affected masticatory efficiency, further evaluations of occlusal modifications should be made. Other occlusal factors should be considered and many more occlusal situations with an increased number of subjects must be studied. CLINICAL
OBSERVATIONS
In only a few instances, after the adjustment period, were complaints registered relative to discomfort, pain, or inability to chew food, regardless of the occlusal pattern. This did not necessarily indicate that the patients had no difficulties in masticaton. It might have indicated that only softer foods were consumed or that the patients had no trouble swallowing their food. I6 A considerable amount of food becamelodged in the occlusal surfaces during the course of masticatory performance tests, thus obliterating the grooves. This clogging of the marked surfaces could have made them similar to the unmarked surfaces and influenced the experimental results. SUMMARY
A study of 20 edentulous subjects was made to evaluate the effect of 4 cuspless geometric occlusal patterns on the chewing efficiency of complete dentures and to compare the masticatory effectiveness of these grooved patterns with similar patterns of raised metal inserts. Results of the tests showed no significant difference in effectiveness among the patterns tested. However, after a year of experience with a given pattern, masticatory efficiency was significantly improved. After three months of experience with metal insert patterns, the patients showed a definite improvement in masticatory performance. Dentures with occlusal configurations on both upper and lower posterior tooth segmentsseemedto be more effective than dentures with one or both opposing segmentsfree of occlusal markings. 1 would like to thank Dr. I. R. Hardy for his guidance and encouragement, and Dr. R. S. Manly for the prerequisite guidance in research. I am especially grateful for the clinical assistance of Dr. H. B. Johnson. I would also like to acknowledge the technical assistance of Dr. Alexander Coulouriotes and the statistical services and advice of Dr. Donald B. Giddon. REFERENCES
1. Sauser, C. W., and Yurkstas, A. A.: The Effect of Various Geometric Occlusal Patterns on Chewing Efficiency, J. PROS. DEN. 7:634, 1957. 2. Thompson, M. J.: Masticatory Efficiency as Related to Cusp Form in Denture Prosthesis, J.A.D.A. 24:207-219, 1937.. 3. Payne>% 79j;lA Study of Posterior Occlusion in Duplicate Dentures, J. PROS. DEN. 1:3224. Trapozzano, V.’ R., and Lazzari, J. B. : An Experimental Study of the Testing of Occlusal Patterns on the Same Denture Bases, J. PROS. DEN. 2:440-457, 1952. 5. Trapozzano, V. R. : Testing of Occlusal Patterns on the Same Denture Base, J. PROS. DEN. 953-69, 1959. 6. Sobolik, C. F.: Observations on Occlusal Forms by an Edentulous Dentist, 0. Items Interest 60:762-771, 1938. Schultz, A. W.: Comfort and Chewing Efficiency in Dentures! J. PROS. DEN. 1:40-41, 1951. 3: Manly, R. S., and Vinton, P.: A Survey of the Chewing Abihty of Denture Wearers, J. D. Res. 30:314-321. 1951.
Volun1e Xumbcr
9. 10. 11. 12. 13. 14. 15. 16.
I3 3
Manly,
GEOhfETRIC
OCCLUSAL
CARVING
461
R. S., and Vintotl, P. : Factors Tnfluencing Denture Function, J. I’ROS. DEN. 1:571%586, 1951. Manly, R. S., and Braley, I,. C.: Masticatory Performance and Efficiellcy, J. D. Rcs. 29:448-462, 1950. Sears, V. H.: Specification for Artificial Posterior Teeth, J. PROS. DEN. 2:35.5, 1952. Hardy, I. R.: Technique for the Use of Nonanatomic Acrylic Posterior Teeth, D. Digest 48 562-566, 1942. Hardy, I. R.: The Developments in the Occlusal Patterns of Artificial Teeth, J. PROS. DE?;. 1 Z-23, 1951. Cochran, W. G., and Cox, G. M.: Experimental Designs, ed. 2, New York, 1957, John Wiley & Sons, Inc. Yurkstas, A. A., and Manly, R. S.: Value of Different Test Foods in Estimating Mastica.tory Ability, J. Appl. Physiol. 3:45-53, 1950. Yurkstas, A. A.: Compensation for Inadequate Masticaticn, Brit. D. J. 91:261, 1951. 136 HARRISON AVENUE BOSTON 11. MASS.
OF GEOMETRIC EFFECTIVENESS
OCCLUSAL CARVINGS ON THE OF COMPLETE DENTURES
A. ALBERT YURKSTAS, B.S., MS., D.M.D.* Tufts University
School of Dental
Medicine,
Boston, Mass.
ANY WORKERS~-~ have studied the chewing efficiency of complete dentures, and
yet, the literature does not reveal the exact role that the occlusal schemeplays in influencing masticatory effectiveness. Sauser and Yurkstasl pointed out that variations in occlusal surface carvings resulted in differences of masticatory performance when overlays were placed on the natural dentition. They suggested two conclusions: “( 1) masticatory performance was better when both upper and lower occlusal surfaces were provided with markings than when one or both were without markings, and (2) highest masticatory performance resulted from the use of occlusal carvings which ran a longitudinal course along the upper occlusal surface regardless of the character of the lower occlusal scheme.” The situation was far different from that in complete dentures which rest on oral mucosa of varying resiliency. Therefore, their conclusions are not valid for complete dentures. Other studies have dealt with the influence of locked versus balanced occlusions,6 and anatomic versus nonanatomic teeth, but factors such as sluicing, tooth position, number of teeth, etc., have not been investigated thoroughly. The purpose of this study was to evaluate the effect of straight-line geometric occlusal carvings on the masticatory effectiveness of complete dentures with an occlusal schemethat conformed to Sears’ll definition of a nonanatomic occlusion. The evaluation of commercially available posterior tooth forms was omitted purposely in order to evaluate certain basic occlusal factors that might influence complete denture efficiency, rather than to determine the most efficient tooth form for a given number of denture wearers. It is imperative to emphasize that the chewing efficiency of complete dentures is not usually the paramount consideration in evaluating their over-all success.The importance of efficient mastication must be weighed together with factors such as comfort, esthetics, phonetics, and the preservation of associated supporting structures. Each of these factors may assumedifferent degrees of importance, depending upon the techniques used, the purpose of the dentist, and, most important, the requirements of the patient. PROCEDURE
Test dentures were constructed for 20 edentulous patients with a technique *Chairman of the Departmeni
of Complete Dentures. 452
453
Fig. markings. Fig.
l.-The
occlusal
Z.-Selected
surfaces
grooved
on one group
patterns
of test dentures
are block
teeth
with
no occlusal
are used on the test dentures.
experience varyadvocated by Hardy. l2 Ten persons had previous denture-wearing ing from 2 to 17 years, and 10 had no previous denture-wearing experience. The patients varied in age from 30 to 6.5 with a mean age of 48. Block-type posterior teeth were used, in which the two bicuspids and first molar tooth were fabricated as a single unit. They resembled the teeth designed by Hardy’” with the exception of metal inserts. The final test dentures were typical of complete dentures, except that the posterior tooth segments consisted of block teeth (Figs. 1 and 2). The occlusal surfaces of the posterior elements were modified, first, by selected grooved patterns and then by addition of metal inserts. As successive modifications were made in the occlusal surfaces, tests were given to determine their effect upon masticatory efficiency. Four grooved patterns were selected1 for testing (Fig. 3.). They included : (1) no markings on the upper or lower occlusal surface (2) longitudinal upper grooves and no markings on the lower occlusal surface, (3) longitudinal upper grooves and buccolingual lower grooves, and (4) longitudinal upper grooves and longitudinal lower grooves. Henceforth, we will refer to the test patterns by
Upper Pattern
Lower
I II
Pattern
2 Eli
Pattern
3 EuIIl
Pattern
4 EEI
Fig. 3.-Diagrammatic
representation
of the patterns
used on the test dentures,
454
J. Pros. Den. May-June, 1963
YURKSTAS
Fig.
4.
Fig.
Fig. 4.-Longitudinal upper and buccolingual occlusal surfaces of the test dentures. Fig. 5.-Longitudinal upper and lower metal
lower strips
metal
are used
5. strips
are
in one group
inserted of test
into
the
dentures.
these numbers. The selection of the type of pattern to be inscribed on the test dentures and the sequence of presentation were based on random tables by Cochran and Cox.14 This procedure tended to minimize the time and learning variables. Grooves were cut into the occlusal surfaces of the acrylic resin posterior teeth with a mounted stone to produce shearing or cutting edges. The grooves were uniformly 1.0 mm. deep and 1.0 mm. wide. When a change in the occlusal markings was desired, the grooves were filled with a cold-curing resin and placed against a glass slab until the resin cured. This technique preserved the original vertical height and buccolingual contour of the occluding surfaces. Strips of Vitallium* were imbedded later in the occlusal surfaces of the test dentures and secured with an autopolymerizing acrylic resin. Two occlusal configurations that corresponded to Patterns 3 and 4 of the grooved surfaces were used (Figs. 4 and 5). The metal inserts projected 1 mm. above the occlusal surface. Masticatory performance tests with peanuts at 20 strokes were conducted on the right and left sides immediately upon completion of the dentures. No carving was present on the occlusal surfaces at this time. The patients wore the test dentures for a one week adjustment period, and reported daily for necessary modifications (Table I). At the end of one week, a selected occlusal pattern was inscribed on the block teeth. The patient then performed a series of mast&tory tests of 20 strokes each on right and left sides (Table II). The test foods were peanuts, carperformance was computed as rots, and ham in 3 Gm. samples. lp7,15 Masticatory the percentage of food that passed through a given screen opening. The tests were repeated at weekly intervals, and a new occlusal pattern was inscribed on the block teeth each week for 4 weeks. Approximately 3 months after the dentures were delivered, the patients were recalled and all 4 grooved occlusal patterns were tested on the same day. Final tests with the grooved patterns were made 9 months later. The patients had been wearing their dentures for 1 year, plus or minus 3 weeks. At this time, all patients were tested with peanuts and ham on both right and left sides, Metal inserts were then imbedded and the testing was continued for another 3 months. RESirLTS
AND
DISCUSSION
The distribution *Supplied
of some of the experimental
by the Austenal
Co. of New
York
City,
N. Y.
data with
peanuts as a test food
puue; ”
;3
GEOMETRIC
OCCLUSAL
455
CARVINGS
is shown in Fig. 6. Not all patients could chew with equal facility, even though the teeth, the occlusal markings, and the denture technique were identical. The masticatory performance of the left and right sides had approximately the same distribution and showed no significant difference. Similar results were found with ham and carrots as test foods (Fig. 7). The results obtained with the grooved patterns over the 1 year testing period are shown in Fig. 8. The findings led to these observations: (1) At any stage of the experiment, there were no significant differences in masticatory efficiency TABLE
I.
SCHEDULE
OF THE EXPERIMENTAL
TIME AFTER INSERTION
APPT. NO.
APPOINTMENTS
PROCEDURE --__--
__I
0
1-8 1:
i l&Y 4 days
11
12 z”-iZiT
1.3
3 weeks 4 weeks
:I: 16
5 3 12 15
17 ii
weeks months months months
Patients examined and selected Dentures constructed Dentures inserted and unmarked pattern tested Adjustment appointment Adjustment appointment Adjustment appointment. First test pattern inscribed First test pattern tested and removed, second pattern Second test pattern tested and removed, third pattern Third test pattern tested and removed, fourth pattern Fourth test pattern tested All patterns retested Final pattern retested. Inserts imbedded and tested Insert pattern retested
PEANUTS c&s
Fig.
G.-Typical
distribution
of peanut
(Ona Week) PNTERH 0-
masticatory
performance
test
scores.
inscribed inscribed inscribed
456
J. Pros. May-June,
YURKSTAS
Den. 1963
among the 4 grooved patterns tested. (2) Tests made 1 week after inscribing a new pattern failed to show a statistically significant improvement in masticatory performance over the first day it was tested. Little or no learning occured during this 1 week period. ‘(3) At the 3 month interval, there as a definite improvement in masticatory performance, but the improvement over the day of insertion was not great enough to be statistically significant. (4) When the first day scores and the 1 week scores for grooved patterns were compared with the 1 year score, the improvement in masticatory performance was statistically significant. Data on the test results obtained for each patient’s preferred side of chewing with both grooved patterns and metal inserts are seen in Fig. 9 (peanuts) and Fig.
TABLE
II.
MASTICATORY
PERFORMANCE
SCORES:
ALL
PATIENTS
AND
ALL
FOODS
PATTERNSTESTED TEST FOOD
Peanuts
CONDITIONS OF TEST
1st day
------_____ STROKES
R* kS.
22.1 21.1 22.2
21.5 22.4 22.1
z; 27.0
22.8 22.3 22.4
L” P.S.
19.9 20.9 20.9
20.9 22.8 23.9
22.1 24.2 25.1
23.7 23.0 24.7
1 P.S. 2 P.S.
30.7 31.6
29.0 30.8
27.8 31.1
27.6 29.9
L” P.S.
37.8 41.3 40.0
33.7 37.6 36.6
Inserts 1 year
R L P.S.
40.7 44.3 42.5
38.1 39.3 39.7
Inserts 1.5 months
R L P.S.
45.3 54.0 48.3
2:: 48.5
1 week
R
3 months
bS P:S:
6.9 6.4 6.9 11.7
7.0 7.0 7.0 13.9
36.0 36.8 38.5
27.5 28.3 22.5
24.3 28.0 27.5 25.2
25.6
33.0 30.8 29.3
23.0 26.6 27.6
1. week
3 months 1 year
Carrots
Inserts 15 months
Ham
Inserts 1 year
5.3 4.0 4.4 11.7
R L P.S.
1 week 3 months
3.7 5.7 4.8 9.7
L” P.S. P.S. L” P.S.
19.9 18.4 20.5 28.7
21.5 22.0 22.4 27.2
22 28.4
10 (carrots and ham). The results led to these observations: (1) VVhen metal illsert patterns were substituted and tested on the same day of the 1 year test with grooved patterns, no significant difference in masticatory performance was apparent. (2) At the 15 month level, after 3 months’ use of the metal-insert patterns, masticatory performance was substantially better than performance with grooved patterns at the 1 year level. The improvement was statistically significant to the 5 per cent level. Lack of a control group makes it hazardous to attribute this improvement to the metal inserts alone. Over-all evaluation of test results with ham as a test food suggests that it has
PATTERN
Fig.
8.-Masticatory
c3
E
[7
CD!
performance
tests over
a one year
period.
4.58
J. Pros. Den. May-June, 1963
YURKSTAS
55 _ Upper
Lower
ir
- /J=
Pattern
I
on
0
- &j:
Pattern
2
50 Eam EB
“p”- q
=Pattern
3
gi
=Poitarn
4
- fJ
’::
0’
I Doy
:
I Week Grooves
G~OOVSS
Grooves
Grooves
I’I’ II,li;’ Year Inserts
rths lnserrs
Time Fig.
9.-Masticatory
performance
tests
on the preferred
side with
Cl
Pattern
I
IsI
Pottern
2 E
if%?
q PotternE llul Pattern4 M
40
peanuts.
0
lllll R
0 3 Months
Grooves
15 Months
Cmots
I Week
Inserts
Grooves
Months Ham
Grooves
I Year t Horn Inserts
Time Fig.
lO.-Masticatory
performance
tests with
carrots
and ham on the preferred
side.
Volume Number
13 3
GEOMETRIC
OCCLITSAT,
459
CARVINGS
little value in such a study as this. No statistically significant differences could he demonstrated among the test scores for the unmarked patterns, grooved patterns, and metal-insert patterns with this food. Tests made at different time intervals revealed only slight differences of no statistical significance. These findings suggest that foods such as ham offer little difficulty to denture wearers. Experimental results obtained with carrots are quite limited. At the 3 month level no significant differences could be demonstrated among the patterns tested. An experimental error of the use of 20 strokes with the first 2 tests and 40 strokes with the final test was committed. The analysis of these data is omitted. The results did suggest that the value of carrots as a test food should be more fully exploited. When data derived from Patterns 3 and 4 were compared (Figs. 9 and IO), there was lit.tle difference between the two patterns. This suggested the generalization that under these tests conditions differences in geometric patterns inscribed on the occlusal surfaces produced little difference in masticatory performance.
50 _
u 2 E ;; r z 6
45 403530 -
s 25.!! 2 zoz 15 _ IO 5first ciw day week
I
I
I
I
three months
y%
.zr Inserts
fifteen months mssrts
Time Fig.
Il.---Comparison
of the
masticatory
performance
tests
on
the
left
and
right
sides.
The masticatory performance results on the left and right sides of Pattern 4 are shown in Fig. 11. No statistically significant difference existed between the left and right sides. A trend was observed which indicated that complete dentures with occlusal markings on both upper and lower posterior tooth segments were more effective than dentures which had one or both opposing tooth segments free from occlusal markings. Observations also suggested that adequate escapeways for masticated food had an influence on the masticatory effectiveness of a given occlusal surface.
460
YURKSTAS
J. Pros. May-June,
Den. 1963
Although the results of this study did not indicate that these modifications of the occlusal surface greatly affected masticatory efficiency, further evaluations of occlusal modifications should be made. Other occlusal factors should be considered and many more occlusal situations with an increased number of subjects must be studied. CLINICAL
OBSERVATIONS
In only a few instances, after the adjustment period, were complaints registered relative to discomfort, pain, or inability to chew food, regardless of the occlusal pattern. This did not necessarily indicate that the patients had no difficulties in masticaton. It might have indicated that only softer foods were consumed or that the patients had no trouble swallowing their food. I6 A considerable amount of food becamelodged in the occlusal surfaces during the course of masticatory performance tests, thus obliterating the grooves. This clogging of the marked surfaces could have made them similar to the unmarked surfaces and influenced the experimental results. SUMMARY
A study of 20 edentulous subjects was made to evaluate the effect of 4 cuspless geometric occlusal patterns on the chewing efficiency of complete dentures and to compare the masticatory effectiveness of these grooved patterns with similar patterns of raised metal inserts. Results of the tests showed no significant difference in effectiveness among the patterns tested. However, after a year of experience with a given pattern, masticatory efficiency was significantly improved. After three months of experience with metal insert patterns, the patients showed a definite improvement in masticatory performance. Dentures with occlusal configurations on both upper and lower posterior tooth segmentsseemedto be more effective than dentures with one or both opposing segmentsfree of occlusal markings. 1 would like to thank Dr. I. R. Hardy for his guidance and encouragement, and Dr. R. S. Manly for the prerequisite guidance in research. I am especially grateful for the clinical assistance of Dr. H. B. Johnson. I would also like to acknowledge the technical assistance of Dr. Alexander Coulouriotes and the statistical services and advice of Dr. Donald B. Giddon. REFERENCES
1. Sauser, C. W., and Yurkstas, A. A.: The Effect of Various Geometric Occlusal Patterns on Chewing Efficiency, J. PROS. DEN. 7:634, 1957. 2. Thompson, M. J.: Masticatory Efficiency as Related to Cusp Form in Denture Prosthesis, J.A.D.A. 24:207-219, 1937.. 3. Payne>% 79j;lA Study of Posterior Occlusion in Duplicate Dentures, J. PROS. DEN. 1:3224. Trapozzano, V.’ R., and Lazzari, J. B. : An Experimental Study of the Testing of Occlusal Patterns on the Same Denture Bases, J. PROS. DEN. 2:440-457, 1952. 5. Trapozzano, V. R. : Testing of Occlusal Patterns on the Same Denture Base, J. PROS. DEN. 953-69, 1959. 6. Sobolik, C. F.: Observations on Occlusal Forms by an Edentulous Dentist, 0. Items Interest 60:762-771, 1938. Schultz, A. W.: Comfort and Chewing Efficiency in Dentures! J. PROS. DEN. 1:40-41, 1951. 3: Manly, R. S., and Vinton, P.: A Survey of the Chewing Abihty of Denture Wearers, J. D. Res. 30:314-321. 1951.
Volun1e Xumbcr
9. 10. 11. 12. 13. 14. 15. 16.
I3 3
Manly,
GEOhfETRIC
OCCLUSAL
CARVING
461
R. S., and Vintotl, P. : Factors Tnfluencing Denture Function, J. I’ROS. DEN. 1:571%586, 1951. Manly, R. S., and Braley, I,. C.: Masticatory Performance and Efficiellcy, J. D. Rcs. 29:448-462, 1950. Sears, V. H.: Specification for Artificial Posterior Teeth, J. PROS. DEN. 2:35.5, 1952. Hardy, I. R.: Technique for the Use of Nonanatomic Acrylic Posterior Teeth, D. Digest 48 562-566, 1942. Hardy, I. R.: The Developments in the Occlusal Patterns of Artificial Teeth, J. PROS. DE?;. 1 Z-23, 1951. Cochran, W. G., and Cox, G. M.: Experimental Designs, ed. 2, New York, 1957, John Wiley & Sons, Inc. Yurkstas, A. A., and Manly, R. S.: Value of Different Test Foods in Estimating Mastica.tory Ability, J. Appl. Physiol. 3:45-53, 1950. Yurkstas, A. A.: Compensation for Inadequate Masticaticn, Brit. D. J. 91:261, 1951. 136 HARRISON AVENUE BOSTON 11. MASS.