- Email: [email protected]
The prevalence of tooth contact in eccentric movements of the jaw: its clinical implications
44/402 • THE JO URNAL OF THE A M E R IC A N DENTAL A SSO C IA TIO N
either for a short period or for a length of time, such as military service, his practice will be properly cared for and ethically returned to him when he comes back. Someone said “A n institution is but the lengthening shadow of one man.” This is usually very true in dental groups at the start, but as ihe group grows the shadows of many men merge to strengthen that institution.
Las,t, and to me the greatest advan tage of all, is the spirit of fraternity that binds our group together and makes the practice of dentistry a thing of great joy. Truly I can say as I greet my associates in the hall every morning, “ It’s going to be a great day!” 2 5 0 0 Bissell A v e n u e Presented before the Eleventh National Dental Health Conference, American Dental Association, Chicago, April 25-27, I960.
The prevalence of tooth contact in eccentric m ovem ents of the jaw : its clinical im plications
L a w re n ce A . W ein b e r g , D .D .S ., B rooklyn , N . Y .
S ixty patien ts w ere exa m in ed fo r signs o f tooth to to o th co n ta ct in e cc en tric p osi tions o f the jaw s. O f
1,540 tee th
ex
a m in ed , 1,309 ( 8 4 p e r c e n t ) exh ib ited w ear fa cets. T h e e x a ct cause o f to o th to tooth con ta cts has n ot b een established. O cclu sa l equ ilibration tech n ics and re con stru ctiv e
d en tistry
shou ld
p ro d u ce
h arm oniou s ecc en tric co n ta ct as w ell as g o o d cen tric occlu sion .
T h e classic concepts of occlusal equilibra tion pioneered by Box,1 Schuyler,2 and Sorrin3 have been severely challenged in recent years. Some claim that the teeth do not meet when chewing except during deglutition.4 Tooth to tooth contact in eccentric positions of the jaws is attrib uted to bruxism and dismissed as a minor problem. I f this theory is accepted as the truth, then occlusal equilibration1' 3’ 5'8 would
consist of preliminary grinding and cen tric correction only. A ll attempts to im prove eccentric contact in complete den tures and complete mouth reconstruction would be superfluous; fixed and remov able prostheses could be constructed on a simple hinge articulator. Accurate imi tation of certain eccentric condylar move ments with the gnathoscope9 and all at tempts to learn more about the various guidances of mandibular movements10"12 might be viewed as academic with little practical value. T h e object of this article is to examine the extent of tooth to tooth contact in eccentric positions. I f the majority of patients exhibit these contacts then the goal in therapy must be to provide an equilibrated occlusion in centric and in eccentric positions. Tooth to tooth contact, when the jaw is in eccentric positions, creates a sharply delineated area ■of wear commonly re ferred to as a “ wear facet.” These wear
W EINBERG . . . VO LUM E 62, APRIL 1961 • 45/403
facets are located on the tooth surfaces related to working, balancing, and pro trusive excursions. Sometimes they occur as a result of atypical individual habits. Sharply delineated wear facets should not be confused with the rounding effect of food abrasion. The majority of eccentric wear facets occur as a result of occasional occlusal contact or habitual bruxism. The teeth can penetrate a soft bolus but, for the pur poses of this paper, it is not important whether the teeth actually penetrate the bolus. The important fact is that if ec centric wear facets are present they re flect actual tooth to tooth contact. M ETH O D
A random selection of 60 patients having at least 20 contacting teeth was used as a preliminary requirement; the patients were not selected on the basis of the exist
the root length, (5 ) bone loss up to two thirds of the root length. Each patient was asked if he was aware of clenching or grinding his teeth. OBSERVATIONS
O f the 60 patients used in this study, 59 (98.3 per cent) showed some signs of tooth to tooth contact in eccentric posi tions. A total of 1,540 teeth was examined and 1,309 (84 per cent) exhibited eccen tric wear facets. Working side facets were observed on 822 teeth and 414 teeth exhibited balanc ing side facets. Thus there were approxi mately half as many wear facets on the balancing side as on the working side. A history of each of the 60 patients revealed that 48 were aware of occa sional occlusal clenching, or gritting or rubbing the teeth together. Only two pa tients reported an awareness of habitual
ence or absence of periodontal disease, although the information was recorded in the observations. Study casts and a full mouth series of roentgenograms were made of each patient in the study. The number of patients showing signs of ec centric wear facets was recorded as well as the number o f teeth exhibiting eccen
clenching and bruxism. The remaining ten patients denied any knowledge of tooth contact other than during the swal lowing and chewing of food. The periodontal condition of each pa
tric wear facets (see table). For comparative purposes' the number of working side and balancing side facets was recorded separately. The occlusal portions of the cusps are described as the buccal or lingual cusp inclines ; the buccal and lingual surfaces of the cusps are de scribed as the buccal or lingual slopes. Working side facets occur when the lower buccal slope contacts the upper buccal cusp incline and the lower lingual cusp
thirds of the root length. The etiology of periodontal disease is too broad to per mit any conclusions about its relation to bruxism on the basis of this study.
incline contacts the upper lingual slope. Balancing side facets occur when the lower buccal cusp incline contacts the upper lingual cusp incline. The periodontal conditions were classi
exhibited more wear than others as well as multiple facet formation caused by protrusive as well as lateral movements. N o attempt was made to classify the degree of wear o f the facets in relation to missing teeth, age, or emotional factors. A similar preliminary report on 40 pa tients13 revealed that 39 had evidences of
fied as: (1) normal, (2 ) gingivitis, (3) bone loss up to one third of the root length, (4) bone loss up to one half of
tient was noted for general information. The conditions varied from normal gin gival tone through bone loss up to two
D ISC U SSIO N OF OBSERVATIONS
Fifty-nine of the 60 patients studied (98.3 per cent) showed sharply delineated wear facets caused by tooth contacts when the jaw was in eccentric positions. Some teeth
46/404 • THE JO U R N A L OF THF A M E R IC A N DENTAL A SSO C IA T IO N
Table • Observations made in study of tooth contact in eccentric positions Patient no.
Occasional bruxism
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
yes yes yes no yes yes yes yes yes no yes no yes yes yes yes yes no yes yes yes no yes no no yes yes yes yes yes yes no yes no yes habitual yes yes yes yes yes yes yes yes no yes yes yes yes yes yes yes yes yes yes habitual yes yes yes yes
Total
No. of teeth
N o. of teeth with facets
Working side facets
Balancing side facets
28 29 25 26 27 30 28 30 28 28 20 26 25 26 30 27 27 22 27 20 28 21 24 26 27 28 26 27 27 22 24 27 26 27 24 28 23 28 29 28 28 26 22 24 25 29 31 23 21 29 23 23 26 24 30 32 23 26 20 26
26 29 12 26 27 26 21 18 28 none 20 26 20 26 12 (anterior) 27 25 18 25 20 28 16 21 4 27 24 23 27 9 22 24 8 22 18 22 28 23 20 27 26 28 26 21 20 23 29 29 22 21 17 23 23 23 22 28 30 18 13 20 22
14 22 12 16 18 20 20 10 20 none 12 18 17 18 none 18 16 10 15 12 18 8 13 2 19 12 15 20 9 14 15 4 14 10 14 20 14 14 16 18 16 16 14 14 12 19 18 12 12 16 18 15 12 12 14 18 12 8 13 12
12 14 8 10 12 12 16 8 8 none 8 6 none 8 none 8 8 none 8 6 8 2 5 — 14 10 10 4 4 8 9 4 4 4 8 14 10 8 10 12 12 8 — 4 6 12 14 10 10 10 . 10 8 8 ■ — 12 4 — 2
1,560
1,309
822
414
6
—
Periodontal condition
Zz
bone loss Ms bone loss gingivitis bone loss gingivitis gingivitis gingivitis bone loss gingivitis gingivitis gingivitis bone loss bone loss Z3 bone loss Ms bone loss bone loss gingivitis Mi bone loss bone loss bone loss bone loss bone loss bone loss bone loss Z2 bone loss normal bone loss bone loss bone loss bone loss bone loss normal normal gingivitis gingivitis gingivitis bone loss Vincent's gingivitis gingivitis gingivitis bone loss bone loss gingivitis ■ bone loss gingivitis gingivitis bone loss bone loss bone loss bone loss gingivitis bone loss gingivitis bone loss gingivitis bone loss gingivitis Z2 bone loss bone loss
Zz
Vz
Zz Zz
Zz
Zz Zz Zz Zz Zi Zz Zz Zz Zz Zz Zz
Zz
Vz Zz Zz
Zz Zz Zz Zz Zz Zz Zz Zz
W EINBERG . . . VO LUM E 62, APRIL 1961 • 47/405
tooth to tooth contact in eccentric posi tions. I f both reports are combined, 98 of the 100 patients examined showed evi dence of tooth to tooth contact in eccen tric positions; 83 per cent of the total 2,656 teeth examined had one or more eccentric wear facets. The evidence indicates that a majority of patients have tooth to tooth contacts in eccentric positions. It is reasonable to conclude that therapy, whether it is peri odontal or reconstructive, should provide harmonious eccentric relationships. R e construction should be performed with the aid of an adjustable articulator of choice followed by occlusal adjustments in the mouth as necessary. Forty-eight o f the 60 patients indi cated that they were aware of occasional occlusal clenching or grinding or both.
terceptive contacts in the second and third molars on the balancing side, (2) temporomandibular impingement during the anteromedial movement of the con dyle on the balancing side aiid (3) muscle complex imbalance (entire mandibular musculature) due to excessive lateral ex cursions in a horizontal transverse plane. Cuspid contact during the extended range of lateral excursions does not con tradict the idea of equilibrated contacts in lateral excursions through the normal range o f motion. It also does not imply a cuspid protected occlusion during all ranges of lateral excursions. The nor mal range of the lateral bruxism type
T en denied any knowledge of even occa sional clenching or grinding although they exhibited eccentric wear facets. Only two
of movement is from centric occlusion to the molar cusp height. Deviation from this motion would be considered an atypical individual habit pattern. Interceptive contacts on the balancing side can mechanically produce greater torque than when they occur on the
patients admitted habitual clenching and grinding. It was not objectively deter mined if the patients that admit to occa sional clenching are prone to habitual
working side.14 These added forces asso ciated with bruxism may contribute to periodontal disease15" 17 and temporo mandibular dysfunction.
bruxism. Therefore, it cannot be said that the eccentric wear facets observed in the majority of the patients were due to ha bitual bruxism.
C O N C L U S IO N S
most often included the cuspid and bi cuspid teeth. Extreme lateral movements, past the cusp heights posteriorly, resulted in only cuspid contact on the working side. Fewer balancing side contacts were observed than on the working side. It may be significant that a larger number
O n the basis of the patients studied, it is thought that some distinction should be made between the etiology and effect of occasional and habitual clenching and bruxism. A majority of patients show eccentric wear facets which indicate ec centric occlusal contacts. The exact cause of these tooth to tooth contacts has not been established although occasional clenching and bruxism movements seem to play a major role. Occlusal equilibra tion technics and reconstructive dentistry,
of balancing contacts were evident than is commonly accepted as the average. These balancing side contacts often in cluded the second and third molars.
therefore, should produce harmonious eccentric contact as well as good centric occlusion. 51 5 O ce a n A v e ., B rooklyn , N . Y.
During the extended lateral range of motion, past the posterior cusp heights, the working side cuspid contact may pro tect the patient fro m : (1) continued in-
I. Box, H. K. Traumatic occlusion and traumatogenic occlusion. Oral Health 20:642 Dec. 1930.
M any more patients should be exam ined to substantiate a trend that was ob served. Although the working side facets were widely distributed, these contacts
48/406 • THE JO U R N A L O F THE A M E R IC A N DENTAL A SSO C IA T IO N
2. Schuyler, C . H. The correction of occlusal dishar mony of the natural dentition. New York D. J . 13:445 Oct. 1947. 3. Sorrin, S. Traumatic occlusion, Its detection and correction. D. Digest 40:170 May; 202 June 1934. 4. Jankelson, B. Physiology of the human dental oc clusion. J.A .D .A . 50:664 June 1955. 5. Miller, S. C . Textbook of periodontia, ed. 3, Philadelphia, The Blakiston Co., 1950, p. 343-384. 6. Blass, J . L. Occlusal equilibration in periodontal treatment. New York D. J . 22:121 March 1956. 7. Simring, M. Occlusal equilibration of the denti tion. J.A .D .A . 56:643 May 1958. 8. Weinberg, L. A . A visualized technique of occlusal equilibration. J . D. Me.d, 7:9\Jan. 1952. 9. McCollum, B. B. Fundamentals involved in pre scribing restorative dental remedies. D. Items Interest 61:522 June; 641 July; 724 Aug.; 852 Sept.; 942 Oct. 1939.
10. Cohen, R. The relationship of anterior guidance to condylar guidance in mandibular movement. J . Pros. Den. 6:758 Nov. 1956. 11. Weinberg, L. A . The transverse hinge axis: real or imaginary. J . Pros. Den. 9:607 July-Aug. 1959. 12. Weinberg, L. A . Incisal and condylar guidance in relation to cuspal inclination in lateral excursions. J . Pros. Den. To be published. 13.. Weinberg, L. A . Occlusal equilibration in ec centric positions. New York D. J . 23:310 Aug.-Sept. 1957. 14. Weinberg, L. A . Force distribution in mastica tion, clenching, and bruxism. D. Digest 63:58 Feb.; 116 March 1957. 15. Sorrin, S. Traumatic occlusion and occlusal equi libration. J.A .D .A . 57:477 Oct. 1958. 16. Blass, J . L. Personal communication. 17. Witkin, George. Personal communication.
Looking ahead in pedodontics
R a lp h E . M c D o n a ld ,* D .D .S ., M .S ., In d ian apolis
In terest in d en tistry fo r child ren w ill c o n tinu e to
rise and will be
reflected in
chan ges in u n d erg ra d u a te, grad u ate and postgradu ate ed u ca tion . T h e p ed od on tist will assum e m o r e responsibility fo r m in or to o th m o v e m e n t and o rth o d o n tic p r e v e n tive p ro ced u res. P r ev e n tiv e p r o ced u res to c o n tro l caries an d in fla m m atory changes in th e g in g iva l and su p p ortin g tissues will be w id ely a c ce p ted . R esea rch in p e d o d on tics alread y en com passes alm ost all aspects o f d entistry. T h e r e is a pressing n eed fo r e x p a n d e d clin ical research, p a r ticularly in su ch su b jects as child b e h avior, oral habits, th e rea ction o f teeth to tra um atic in ju ry, and p eriod on ta l dis ease in child ren .
In an incredibly short time, slightly over 30 years, the practice of dentistry for children has grown and has become rec ognized as one of the most important,
if not the most important, responsibility of the dental profession. The founders of the first organization in pedodontics, The American Society of Dentistry for Chil dren, could not have foreseen in 1927 such phenomenal growth and recogni tion of this part o f the practice of den tistry. It is difficult, therefore, to discuss “Looking Ahead in Pedodontics” without perhaps being unrealistically conservative in estimating what the accomplishments will be in the future. Dental caries continues to be the num ber one problem in dentistry, and in everyday practice this problem should re ceive major attention, not only from the standpoint o f restorative procedures, but in preventive procedures designed to re duce the problem. M any studies1"3 have been conducted recently to determine the dental needs of children and young adults. Almost without exception, these surveys show that the dental caries prob lem is still acute. Dental caries begins at a very early
either for a short period or for a length of time, such as military service, his practice will be properly cared for and ethically returned to him when he comes back. Someone said “A n institution is but the lengthening shadow of one man.” This is usually very true in dental groups at the start, but as ihe group grows the shadows of many men merge to strengthen that institution.
Las,t, and to me the greatest advan tage of all, is the spirit of fraternity that binds our group together and makes the practice of dentistry a thing of great joy. Truly I can say as I greet my associates in the hall every morning, “ It’s going to be a great day!” 2 5 0 0 Bissell A v e n u e Presented before the Eleventh National Dental Health Conference, American Dental Association, Chicago, April 25-27, I960.
The prevalence of tooth contact in eccentric m ovem ents of the jaw : its clinical im plications
L a w re n ce A . W ein b e r g , D .D .S ., B rooklyn , N . Y .
S ixty patien ts w ere exa m in ed fo r signs o f tooth to to o th co n ta ct in e cc en tric p osi tions o f the jaw s. O f
1,540 tee th
ex
a m in ed , 1,309 ( 8 4 p e r c e n t ) exh ib ited w ear fa cets. T h e e x a ct cause o f to o th to tooth con ta cts has n ot b een established. O cclu sa l equ ilibration tech n ics and re con stru ctiv e
d en tistry
shou ld
p ro d u ce
h arm oniou s ecc en tric co n ta ct as w ell as g o o d cen tric occlu sion .
T h e classic concepts of occlusal equilibra tion pioneered by Box,1 Schuyler,2 and Sorrin3 have been severely challenged in recent years. Some claim that the teeth do not meet when chewing except during deglutition.4 Tooth to tooth contact in eccentric positions of the jaws is attrib uted to bruxism and dismissed as a minor problem. I f this theory is accepted as the truth, then occlusal equilibration1' 3’ 5'8 would
consist of preliminary grinding and cen tric correction only. A ll attempts to im prove eccentric contact in complete den tures and complete mouth reconstruction would be superfluous; fixed and remov able prostheses could be constructed on a simple hinge articulator. Accurate imi tation of certain eccentric condylar move ments with the gnathoscope9 and all at tempts to learn more about the various guidances of mandibular movements10"12 might be viewed as academic with little practical value. T h e object of this article is to examine the extent of tooth to tooth contact in eccentric positions. I f the majority of patients exhibit these contacts then the goal in therapy must be to provide an equilibrated occlusion in centric and in eccentric positions. Tooth to tooth contact, when the jaw is in eccentric positions, creates a sharply delineated area ■of wear commonly re ferred to as a “ wear facet.” These wear
W EINBERG . . . VO LUM E 62, APRIL 1961 • 45/403
facets are located on the tooth surfaces related to working, balancing, and pro trusive excursions. Sometimes they occur as a result of atypical individual habits. Sharply delineated wear facets should not be confused with the rounding effect of food abrasion. The majority of eccentric wear facets occur as a result of occasional occlusal contact or habitual bruxism. The teeth can penetrate a soft bolus but, for the pur poses of this paper, it is not important whether the teeth actually penetrate the bolus. The important fact is that if ec centric wear facets are present they re flect actual tooth to tooth contact. M ETH O D
A random selection of 60 patients having at least 20 contacting teeth was used as a preliminary requirement; the patients were not selected on the basis of the exist
the root length, (5 ) bone loss up to two thirds of the root length. Each patient was asked if he was aware of clenching or grinding his teeth. OBSERVATIONS
O f the 60 patients used in this study, 59 (98.3 per cent) showed some signs of tooth to tooth contact in eccentric posi tions. A total of 1,540 teeth was examined and 1,309 (84 per cent) exhibited eccen tric wear facets. Working side facets were observed on 822 teeth and 414 teeth exhibited balanc ing side facets. Thus there were approxi mately half as many wear facets on the balancing side as on the working side. A history of each of the 60 patients revealed that 48 were aware of occa sional occlusal clenching, or gritting or rubbing the teeth together. Only two pa tients reported an awareness of habitual
ence or absence of periodontal disease, although the information was recorded in the observations. Study casts and a full mouth series of roentgenograms were made of each patient in the study. The number of patients showing signs of ec centric wear facets was recorded as well as the number o f teeth exhibiting eccen
clenching and bruxism. The remaining ten patients denied any knowledge of tooth contact other than during the swal lowing and chewing of food. The periodontal condition of each pa
tric wear facets (see table). For comparative purposes' the number of working side and balancing side facets was recorded separately. The occlusal portions of the cusps are described as the buccal or lingual cusp inclines ; the buccal and lingual surfaces of the cusps are de scribed as the buccal or lingual slopes. Working side facets occur when the lower buccal slope contacts the upper buccal cusp incline and the lower lingual cusp
thirds of the root length. The etiology of periodontal disease is too broad to per mit any conclusions about its relation to bruxism on the basis of this study.
incline contacts the upper lingual slope. Balancing side facets occur when the lower buccal cusp incline contacts the upper lingual cusp incline. The periodontal conditions were classi
exhibited more wear than others as well as multiple facet formation caused by protrusive as well as lateral movements. N o attempt was made to classify the degree of wear o f the facets in relation to missing teeth, age, or emotional factors. A similar preliminary report on 40 pa tients13 revealed that 39 had evidences of
fied as: (1) normal, (2 ) gingivitis, (3) bone loss up to one third of the root length, (4) bone loss up to one half of
tient was noted for general information. The conditions varied from normal gin gival tone through bone loss up to two
D ISC U SSIO N OF OBSERVATIONS
Fifty-nine of the 60 patients studied (98.3 per cent) showed sharply delineated wear facets caused by tooth contacts when the jaw was in eccentric positions. Some teeth
46/404 • THE JO U R N A L OF THF A M E R IC A N DENTAL A SSO C IA T IO N
Table • Observations made in study of tooth contact in eccentric positions Patient no.
Occasional bruxism
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
yes yes yes no yes yes yes yes yes no yes no yes yes yes yes yes no yes yes yes no yes no no yes yes yes yes yes yes no yes no yes habitual yes yes yes yes yes yes yes yes no yes yes yes yes yes yes yes yes yes yes habitual yes yes yes yes
Total
No. of teeth
N o. of teeth with facets
Working side facets
Balancing side facets
28 29 25 26 27 30 28 30 28 28 20 26 25 26 30 27 27 22 27 20 28 21 24 26 27 28 26 27 27 22 24 27 26 27 24 28 23 28 29 28 28 26 22 24 25 29 31 23 21 29 23 23 26 24 30 32 23 26 20 26
26 29 12 26 27 26 21 18 28 none 20 26 20 26 12 (anterior) 27 25 18 25 20 28 16 21 4 27 24 23 27 9 22 24 8 22 18 22 28 23 20 27 26 28 26 21 20 23 29 29 22 21 17 23 23 23 22 28 30 18 13 20 22
14 22 12 16 18 20 20 10 20 none 12 18 17 18 none 18 16 10 15 12 18 8 13 2 19 12 15 20 9 14 15 4 14 10 14 20 14 14 16 18 16 16 14 14 12 19 18 12 12 16 18 15 12 12 14 18 12 8 13 12
12 14 8 10 12 12 16 8 8 none 8 6 none 8 none 8 8 none 8 6 8 2 5 — 14 10 10 4 4 8 9 4 4 4 8 14 10 8 10 12 12 8 — 4 6 12 14 10 10 10 . 10 8 8 ■ — 12 4 — 2
1,560
1,309
822
414
6
—
Periodontal condition
Zz
bone loss Ms bone loss gingivitis bone loss gingivitis gingivitis gingivitis bone loss gingivitis gingivitis gingivitis bone loss bone loss Z3 bone loss Ms bone loss bone loss gingivitis Mi bone loss bone loss bone loss bone loss bone loss bone loss bone loss Z2 bone loss normal bone loss bone loss bone loss bone loss bone loss normal normal gingivitis gingivitis gingivitis bone loss Vincent's gingivitis gingivitis gingivitis bone loss bone loss gingivitis ■ bone loss gingivitis gingivitis bone loss bone loss bone loss bone loss gingivitis bone loss gingivitis bone loss gingivitis bone loss gingivitis Z2 bone loss bone loss
Zz
Vz
Zz Zz
Zz
Zz Zz Zz Zz Zi Zz Zz Zz Zz Zz Zz
Zz
Vz Zz Zz
Zz Zz Zz Zz Zz Zz Zz Zz
W EINBERG . . . VO LUM E 62, APRIL 1961 • 47/405
tooth to tooth contact in eccentric posi tions. I f both reports are combined, 98 of the 100 patients examined showed evi dence of tooth to tooth contact in eccen tric positions; 83 per cent of the total 2,656 teeth examined had one or more eccentric wear facets. The evidence indicates that a majority of patients have tooth to tooth contacts in eccentric positions. It is reasonable to conclude that therapy, whether it is peri odontal or reconstructive, should provide harmonious eccentric relationships. R e construction should be performed with the aid of an adjustable articulator of choice followed by occlusal adjustments in the mouth as necessary. Forty-eight o f the 60 patients indi cated that they were aware of occasional occlusal clenching or grinding or both.
terceptive contacts in the second and third molars on the balancing side, (2) temporomandibular impingement during the anteromedial movement of the con dyle on the balancing side aiid (3) muscle complex imbalance (entire mandibular musculature) due to excessive lateral ex cursions in a horizontal transverse plane. Cuspid contact during the extended range of lateral excursions does not con tradict the idea of equilibrated contacts in lateral excursions through the normal range o f motion. It also does not imply a cuspid protected occlusion during all ranges of lateral excursions. The nor mal range of the lateral bruxism type
T en denied any knowledge of even occa sional clenching or grinding although they exhibited eccentric wear facets. Only two
of movement is from centric occlusion to the molar cusp height. Deviation from this motion would be considered an atypical individual habit pattern. Interceptive contacts on the balancing side can mechanically produce greater torque than when they occur on the
patients admitted habitual clenching and grinding. It was not objectively deter mined if the patients that admit to occa sional clenching are prone to habitual
working side.14 These added forces asso ciated with bruxism may contribute to periodontal disease15" 17 and temporo mandibular dysfunction.
bruxism. Therefore, it cannot be said that the eccentric wear facets observed in the majority of the patients were due to ha bitual bruxism.
C O N C L U S IO N S
most often included the cuspid and bi cuspid teeth. Extreme lateral movements, past the cusp heights posteriorly, resulted in only cuspid contact on the working side. Fewer balancing side contacts were observed than on the working side. It may be significant that a larger number
O n the basis of the patients studied, it is thought that some distinction should be made between the etiology and effect of occasional and habitual clenching and bruxism. A majority of patients show eccentric wear facets which indicate ec centric occlusal contacts. The exact cause of these tooth to tooth contacts has not been established although occasional clenching and bruxism movements seem to play a major role. Occlusal equilibra tion technics and reconstructive dentistry,
of balancing contacts were evident than is commonly accepted as the average. These balancing side contacts often in cluded the second and third molars.
therefore, should produce harmonious eccentric contact as well as good centric occlusion. 51 5 O ce a n A v e ., B rooklyn , N . Y.
During the extended lateral range of motion, past the posterior cusp heights, the working side cuspid contact may pro tect the patient fro m : (1) continued in-
I. Box, H. K. Traumatic occlusion and traumatogenic occlusion. Oral Health 20:642 Dec. 1930.
M any more patients should be exam ined to substantiate a trend that was ob served. Although the working side facets were widely distributed, these contacts
48/406 • THE JO U R N A L O F THE A M E R IC A N DENTAL A SSO C IA T IO N
2. Schuyler, C . H. The correction of occlusal dishar mony of the natural dentition. New York D. J . 13:445 Oct. 1947. 3. Sorrin, S. Traumatic occlusion, Its detection and correction. D. Digest 40:170 May; 202 June 1934. 4. Jankelson, B. Physiology of the human dental oc clusion. J.A .D .A . 50:664 June 1955. 5. Miller, S. C . Textbook of periodontia, ed. 3, Philadelphia, The Blakiston Co., 1950, p. 343-384. 6. Blass, J . L. Occlusal equilibration in periodontal treatment. New York D. J . 22:121 March 1956. 7. Simring, M. Occlusal equilibration of the denti tion. J.A .D .A . 56:643 May 1958. 8. Weinberg, L. A . A visualized technique of occlusal equilibration. J . D. Me.d, 7:9\Jan. 1952. 9. McCollum, B. B. Fundamentals involved in pre scribing restorative dental remedies. D. Items Interest 61:522 June; 641 July; 724 Aug.; 852 Sept.; 942 Oct. 1939.
10. Cohen, R. The relationship of anterior guidance to condylar guidance in mandibular movement. J . Pros. Den. 6:758 Nov. 1956. 11. Weinberg, L. A . The transverse hinge axis: real or imaginary. J . Pros. Den. 9:607 July-Aug. 1959. 12. Weinberg, L. A . Incisal and condylar guidance in relation to cuspal inclination in lateral excursions. J . Pros. Den. To be published. 13.. Weinberg, L. A . Occlusal equilibration in ec centric positions. New York D. J . 23:310 Aug.-Sept. 1957. 14. Weinberg, L. A . Force distribution in mastica tion, clenching, and bruxism. D. Digest 63:58 Feb.; 116 March 1957. 15. Sorrin, S. Traumatic occlusion and occlusal equi libration. J.A .D .A . 57:477 Oct. 1958. 16. Blass, J . L. Personal communication. 17. Witkin, George. Personal communication.
Looking ahead in pedodontics
R a lp h E . M c D o n a ld ,* D .D .S ., M .S ., In d ian apolis
In terest in d en tistry fo r child ren w ill c o n tinu e to
rise and will be
reflected in
chan ges in u n d erg ra d u a te, grad u ate and postgradu ate ed u ca tion . T h e p ed od on tist will assum e m o r e responsibility fo r m in or to o th m o v e m e n t and o rth o d o n tic p r e v e n tive p ro ced u res. P r ev e n tiv e p r o ced u res to c o n tro l caries an d in fla m m atory changes in th e g in g iva l and su p p ortin g tissues will be w id ely a c ce p ted . R esea rch in p e d o d on tics alread y en com passes alm ost all aspects o f d entistry. T h e r e is a pressing n eed fo r e x p a n d e d clin ical research, p a r ticularly in su ch su b jects as child b e h avior, oral habits, th e rea ction o f teeth to tra um atic in ju ry, and p eriod on ta l dis ease in child ren .
In an incredibly short time, slightly over 30 years, the practice of dentistry for children has grown and has become rec ognized as one of the most important,
if not the most important, responsibility of the dental profession. The founders of the first organization in pedodontics, The American Society of Dentistry for Chil dren, could not have foreseen in 1927 such phenomenal growth and recogni tion of this part o f the practice of den tistry. It is difficult, therefore, to discuss “Looking Ahead in Pedodontics” without perhaps being unrealistically conservative in estimating what the accomplishments will be in the future. Dental caries continues to be the num ber one problem in dentistry, and in everyday practice this problem should re ceive major attention, not only from the standpoint o f restorative procedures, but in preventive procedures designed to re duce the problem. M any studies1"3 have been conducted recently to determine the dental needs of children and young adults. Almost without exception, these surveys show that the dental caries prob lem is still acute. Dental caries begins at a very early