The effects of dental treatment
on biting force
W. J. Ralph, D.D.Sc., F.R.A.C.D.S.* University
of Melbourne,
School of Dental Science, Melbourne,
Australia
T
1
n a previous article,’ details were given to the effect on a patient’s maximum biting force of the replacement of a poor natural dentition with immediate dentures. During the succeeding 4 years the observations were continued, and the present article reports the results at the end of a total period of 8 years.
METHODS Both men and women patients of different ages were selected from those attending The Royal Dental Hospital of Melbourne. The treatment followed accepted procedures for patients requiring immediate dentures.’ A temperature-compensated wire strain gauge transducer feeding into a direct-reading measuring bridge was used to record biting force. The transducer was machined from a stainless steel alloy and was fitted with hard rubber bite pads which ‘were enclosed in a rubber finger stall. To prevent crossinfection between patients the whole assembly was swabbed with isopropyl alcohol and a fresh sterile finger stall applied prior to its use. The transducer was approximately 4 mm thick so that in use the vertical dimension of occlusion was opened by this amount for all subjects. When sufficient teeth remained, readings were taken on the patient’s first visit. However, this was not always possible, since opposing teeth were frequently missing in the posterior regions. Readings were also taken on the day of the insertion of the dentures, although these were not always successful, mainly because of patient apprehension and the effects of local anesthesia. Successful readings were recorded after 48 hours, when most patients could bite on the instrument with confidence. For each patient, three maximum biting force readings were taken in the anterior region and in the molar/premolar region on both sides of the arch. *Senior
Lecturer,
0022-3913/79/020143
Department
+ 03$00.30/O
of Dental
Prosthetics.
0 1979 The C. V. Mosby
Co.
These readings were averaged. The recording instrument was originally calibrated by dead loading and throughout the observation period was frequently tested by a similar method. Patient visits took place on a 6-month basis, and any treatment that was required such as minor occlusal corrections or adjustments was carried out at those times. If resorption had proceeded to such a level that the original dentures were no longer satisfactory, appointments were arranged to carry out the required treatment as soon as possible. Dentures were considered to be satisfactory at a recall appointment when the retention was good, there was no detectable midline rock and no inflammati0.n at the borders, and the occlusion had not changed since the last visit. In any 12-month period, the treatment varied for individual patients from minor adjustments to new dentures.
RESULTS The attrition of subjects in an 8-year clinical study is inevitably high. Only eight of the original 65 subjects returned for evaluation at the end of 8 years. The subjects were grouped according to sex and type of denture required. The groups were as follows: (1) complete upper denture opposing an essentially complete arch of natural teeth; (2) complete upper denture opposing lower natural teeth in the anterior region with a removable partial denture in the posterior; and (3) complete upper and lower dentures. The results indicate that there was a steady rise in biting force in all subjects for the first 1% to 24-month period. Subsequently a leveling-off took place which was maintained throughout the observation period, provided that follow-up treatment was given. Figs. 1 and 2 illustrate the results of the survey over an 8-year period. An analysis of the treatment that was carried out throughout the investigation showed that each subject had approximately 26 appointments following the extraction visit. The treatment given for each
THE JOURNAL
OF PROSTHETIC
DENTISTRY
143
RALPH
18
34
36
43
30
73
34
36
montnm
Fig. 1. The combined average maximum biting forces for each of the three male groups studied. For the majority of 6-month intervals, the group with complete upper dentures opposed by natural teeth produced the highest forces, while the group with complete upper and lower dentures produced the lowest. The average force levels maintained to the eighth year compared favorably with the average force recorded for young dentulous adult men. Triangle, Complete upper denture opposing natural teeth. Square surrounding a dot, Complete upper denture opposing natural teeth and a removable partial denture. Dot, Complete upper and lower dentures.
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Fig. 2. The combined average maximum biting forces for each of the three female groups studied. At each of the (j-month intervals the group with complete upper dentures opposed by natural teeth recorded the highest forces, while the group with complete upper and lower dentures recorded the lowest forces. The average force levels maintained to the eighth year compared favorably with the average force recorded for young dentulous adult women. Triangle, Complete upper denture opposing natural teeth. Square surrounding a dot, Complete upper denture opposing natural teeth and a removable partial denture. Dot, Complete upper and lower dentures.
144
FEBRUARY
197’9
VOLUME
41
NUMBER
2
DENTAL
TREATMENT
AND
BITING
FORCE
subject averaged five adjustments, three relines, and two remakes. The average useful life of a denture was 2 to 3 years, but there was an indication that this period was increasing toward the end of the survey.
DISCUSSION Clinical examination at recall appointments frequently revealed evidence of resorption by the presence of inflammation at the borders of the denture, a midline rock, and/or some change in the occlusion of the teeth. However, most patients found their dentures quite satisfactory and were reluctant to undergo further dental treatment. However, by demonstrating that their biting force had decreased from the previous visit, the requirements for new dentures or further treatment were more readily accepted. With new or adjusted dentures, the limitation to the force produced was not pain or discomfort, but the possibility that the patients had reached the limit of their muscular activity. Such speculation may be correlated with Johnson’s observations on bone resorption during immediate denture treatment. There appears to be an inverse relationship between bone resorption and biting force, in that after the initial resorption takes place, the dentures apparently “settle in” and there is a steady increase in biting force. Once a.stable base is established and the dentures are maintained in occlusion, an “acceptable” level of force can be achieved. The parameters of this force level are still to be determined by further work on the forces which are required to
COPYRIGHT
masticate the average modern diet. However, the maintenance of such an “acceptable” biting force is probably more important in maintaining muscle tone, facial contours, and a stable bony base than it is from the point of view of mastication alone. Although it might appear that the amount of treatment given over an 8-year period was excessive, it compares reasonably well with what is expected in a specialty practice where patients are g-iven a high level of treatment. The figure was greater than anticipated, probably due to the fact that objective rather than subjective methods were used to assess denture function. This suggests that at the present time an immediate denture treatment program which includes only a reline or new dentures at the appropriate time interval is not optimal treatment. It is therefore suggested that a bite-force meter can be of considerable adjunctive value in assessing the performance level of dentures. REFERENCES 1. 2.
Atkinson, H. F., and Ralph, W. J.: Tooth loss and biting force in man. J Dent Res 52:225, 1973. Johnson, K.: A three year study of the dimensional changes occurring in the maxilla following immediate denture treatment. Aust Dent J 12:152. 1967.
Re@nt requests to: DR. W.J. RALPH UNIVERSITY OF MELBOURNE SCHOOL OF DENTAL SCIENCE 711 ,kIZABETH ST. MELBOURNE. 3000 AUSTRALIA
INFORMATION
The appearance of a code at the bottom of the first page of an original article in this journal indicates the copyright owner’s consent that copies of the article may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per copy fee through the Copyright Clearance Center, Inc., P.O. Box 765, Schenectady, N. Y. 12301, 518-374-4430, for copying beyond that not extend
permitted
by Sections
107 or 108 of the U. S. Copyright
Law.
to other kinds of copying, such as copying for general distribution, promotional purposes, for creating new collective works, or for resale.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
This
consent
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does
or
145
on biting force
W. J. Ralph, D.D.Sc., F.R.A.C.D.S.* University
of Melbourne,
School of Dental Science, Melbourne,
Australia
T
1
n a previous article,’ details were given to the effect on a patient’s maximum biting force of the replacement of a poor natural dentition with immediate dentures. During the succeeding 4 years the observations were continued, and the present article reports the results at the end of a total period of 8 years.
METHODS Both men and women patients of different ages were selected from those attending The Royal Dental Hospital of Melbourne. The treatment followed accepted procedures for patients requiring immediate dentures.’ A temperature-compensated wire strain gauge transducer feeding into a direct-reading measuring bridge was used to record biting force. The transducer was machined from a stainless steel alloy and was fitted with hard rubber bite pads which ‘were enclosed in a rubber finger stall. To prevent crossinfection between patients the whole assembly was swabbed with isopropyl alcohol and a fresh sterile finger stall applied prior to its use. The transducer was approximately 4 mm thick so that in use the vertical dimension of occlusion was opened by this amount for all subjects. When sufficient teeth remained, readings were taken on the patient’s first visit. However, this was not always possible, since opposing teeth were frequently missing in the posterior regions. Readings were also taken on the day of the insertion of the dentures, although these were not always successful, mainly because of patient apprehension and the effects of local anesthesia. Successful readings were recorded after 48 hours, when most patients could bite on the instrument with confidence. For each patient, three maximum biting force readings were taken in the anterior region and in the molar/premolar region on both sides of the arch. *Senior
Lecturer,
0022-3913/79/020143
Department
+ 03$00.30/O
of Dental
Prosthetics.
0 1979 The C. V. Mosby
Co.
These readings were averaged. The recording instrument was originally calibrated by dead loading and throughout the observation period was frequently tested by a similar method. Patient visits took place on a 6-month basis, and any treatment that was required such as minor occlusal corrections or adjustments was carried out at those times. If resorption had proceeded to such a level that the original dentures were no longer satisfactory, appointments were arranged to carry out the required treatment as soon as possible. Dentures were considered to be satisfactory at a recall appointment when the retention was good, there was no detectable midline rock and no inflammati0.n at the borders, and the occlusion had not changed since the last visit. In any 12-month period, the treatment varied for individual patients from minor adjustments to new dentures.
RESULTS The attrition of subjects in an 8-year clinical study is inevitably high. Only eight of the original 65 subjects returned for evaluation at the end of 8 years. The subjects were grouped according to sex and type of denture required. The groups were as follows: (1) complete upper denture opposing an essentially complete arch of natural teeth; (2) complete upper denture opposing lower natural teeth in the anterior region with a removable partial denture in the posterior; and (3) complete upper and lower dentures. The results indicate that there was a steady rise in biting force in all subjects for the first 1% to 24-month period. Subsequently a leveling-off took place which was maintained throughout the observation period, provided that follow-up treatment was given. Figs. 1 and 2 illustrate the results of the survey over an 8-year period. An analysis of the treatment that was carried out throughout the investigation showed that each subject had approximately 26 appointments following the extraction visit. The treatment given for each
THE JOURNAL
OF PROSTHETIC
DENTISTRY
143
RALPH
18
34
36
43
30
73
34
36
montnm
Fig. 1. The combined average maximum biting forces for each of the three male groups studied. For the majority of 6-month intervals, the group with complete upper dentures opposed by natural teeth produced the highest forces, while the group with complete upper and lower dentures produced the lowest. The average force levels maintained to the eighth year compared favorably with the average force recorded for young dentulous adult men. Triangle, Complete upper denture opposing natural teeth. Square surrounding a dot, Complete upper denture opposing natural teeth and a removable partial denture. Dot, Complete upper and lower dentures.
0
3
7
il
A F’N % F’tJ+P . F/P
2
A
A
20
; 12 Y
Q
A
@IQ l
.
l
l
m
A *
1
A
A
Q
.
“r”,..
A
*
A
m*
.
.
.
m
. l
A
.
l
.
. 5
t 13
24
38
02 monthr
20
72
24
32
Fig. 2. The combined average maximum biting forces for each of the three female groups studied. At each of the (j-month intervals the group with complete upper dentures opposed by natural teeth recorded the highest forces, while the group with complete upper and lower dentures recorded the lowest forces. The average force levels maintained to the eighth year compared favorably with the average force recorded for young dentulous adult women. Triangle, Complete upper denture opposing natural teeth. Square surrounding a dot, Complete upper denture opposing natural teeth and a removable partial denture. Dot, Complete upper and lower dentures.
144
FEBRUARY
197’9
VOLUME
41
NUMBER
2
DENTAL
TREATMENT
AND
BITING
FORCE
subject averaged five adjustments, three relines, and two remakes. The average useful life of a denture was 2 to 3 years, but there was an indication that this period was increasing toward the end of the survey.
DISCUSSION Clinical examination at recall appointments frequently revealed evidence of resorption by the presence of inflammation at the borders of the denture, a midline rock, and/or some change in the occlusion of the teeth. However, most patients found their dentures quite satisfactory and were reluctant to undergo further dental treatment. However, by demonstrating that their biting force had decreased from the previous visit, the requirements for new dentures or further treatment were more readily accepted. With new or adjusted dentures, the limitation to the force produced was not pain or discomfort, but the possibility that the patients had reached the limit of their muscular activity. Such speculation may be correlated with Johnson’s observations on bone resorption during immediate denture treatment. There appears to be an inverse relationship between bone resorption and biting force, in that after the initial resorption takes place, the dentures apparently “settle in” and there is a steady increase in biting force. Once a.stable base is established and the dentures are maintained in occlusion, an “acceptable” level of force can be achieved. The parameters of this force level are still to be determined by further work on the forces which are required to
COPYRIGHT
masticate the average modern diet. However, the maintenance of such an “acceptable” biting force is probably more important in maintaining muscle tone, facial contours, and a stable bony base than it is from the point of view of mastication alone. Although it might appear that the amount of treatment given over an 8-year period was excessive, it compares reasonably well with what is expected in a specialty practice where patients are g-iven a high level of treatment. The figure was greater than anticipated, probably due to the fact that objective rather than subjective methods were used to assess denture function. This suggests that at the present time an immediate denture treatment program which includes only a reline or new dentures at the appropriate time interval is not optimal treatment. It is therefore suggested that a bite-force meter can be of considerable adjunctive value in assessing the performance level of dentures. REFERENCES 1. 2.
Atkinson, H. F., and Ralph, W. J.: Tooth loss and biting force in man. J Dent Res 52:225, 1973. Johnson, K.: A three year study of the dimensional changes occurring in the maxilla following immediate denture treatment. Aust Dent J 12:152. 1967.
Re@nt requests to: DR. W.J. RALPH UNIVERSITY OF MELBOURNE SCHOOL OF DENTAL SCIENCE 711 ,kIZABETH ST. MELBOURNE. 3000 AUSTRALIA
INFORMATION
The appearance of a code at the bottom of the first page of an original article in this journal indicates the copyright owner’s consent that copies of the article may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per copy fee through the Copyright Clearance Center, Inc., P.O. Box 765, Schenectady, N. Y. 12301, 518-374-4430, for copying beyond that not extend
permitted
by Sections
107 or 108 of the U. S. Copyright
Law.
to other kinds of copying, such as copying for general distribution, promotional purposes, for creating new collective works, or for resale.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
This
consent
for advertising
does
or
145
