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The Inverted Cusp Tooth*
THE INVERTED CUSP TOOTH* B y R U P E R T E. H A L L , D .D .S., C hicago, 111.
T
H IS paper deals with occlusion in longer retain their finely perfected rela a new, simple and practical manner tions. The case is now a failure, and we free of theories and complicated pro must rebase or remake it, to find that the process merely repeats itself, with the end cedures. It shows the w ay and the means for making more efficient, more comfort result that the patient loses his once w ell able and more nearly permanent dentures, formed, efficient ja w ridges, and is understandable to any dentist and appli thenceforth a dental cripple for life. W ho could be happy in a business— cable to the practice of all. for, indeed, dentistry has a business side After many years’ experience as a practitioner of dentistry, the greater part — delivering to an unsuspecting and of which has been devoted to the specialty trusting public a service so unsatisfac of denture prosthesis, it appeared evident tory? How much better it would be to be to me that the subject, w ith special ref erence to occlusion, was enshrouded in able to make a set of dentures for a much confusion and with many imprac patient that would be efficient and com tical procedures; that, in fact, the dentist fortable, and would be reasonably per was not the master of the subject, but the manent and would preserve the jaw ridges. subject the master of the dentist. The conventional cusp teeth, with In a consideration of occlusion as based their occlusal relations, because of the on the so-called “modern” ideas and interlocked cusps, predetermined and re procedures, results are, on the whole, unsatisfactory and disappointing. The stricted to these relations, are a failure dentures are not efficient nor comfort since they do not provide reciprocal ac able, and they are not so nearly per commodation to compensate for discrep manent as is desirable and possible of ancies arising in their making and for relational changes that occur between the attainment. dentures because of atrophy of the sup B y the time the modern denture can porting tissues, and settling and shifting be made comfortable, the supporting of the dentures. Furthermore, the cusp tissues w ill have become atrophied, which tooth is not efficient because the extent permits relational changes between the and direction of force required to make dentures, and the .whole machine is it so dislodges the dentures and trau thrown out of gear. The once beautifully matizes the supporting tissues. occluded, balanced, interlocking cusps no The secret of the success in eliminating *Read before the Section on Full Dentures at the M idw inter Clinic of the Chicago Den tal Society, Jan . 14, 1930.
Jour. A . D. A., December, 1981
the difficulties enumerated lay in improv ing on the form of tooth employed in denture prosthesis. W ith this thought,
2366
H all— Inverted Cusp Tooth the inverted cusp tooth was conceived and designed. As it is not possible to anchor artificial teeth as natural teeth are anchored in the alveoli of the jaw s to resist the required forces necessary to effect efficient masti cation, it is desirable to provide a form of tooth mechanically suited to the re quirements of the conditions to which it is to be adapted and under which it is to function. There are two points to be considered in the designing of such a tooth: 1. T he cutting, grinding and triturat ing surfaces of the teeth should effect efficient mastication with the minimum amount of muscular force, and direct the forces of mastication favorably to the retention and stabilization of the denture. 2. T he occlusion of the teeth should be reciprocal to compensate for the in evitable relational changes that always occur between the dentures from tissue atrophy and change of jaw relations. The inverted cusp tooth fulfils the foregoing requirements. T he scope of adaptability of the in verted cusp tooth is without lim it. It is equally applicable to all types of cases. It serves in the difficult case in a manner heretofore unequaled, and if used in the more favorable case, it naturally w ill function even better, and w ill insure against the case becoming an “unfavor able” one. T he inverted cusp tooth is not a tooth for the select, difficult case alone, but a tooth for any case-—-a mechanical tooth for artificial use under artificial condi tions. SO M E O F T H E P O IN T S O F A D V A N T A G E I N IN V E R T E D C U S P T E E T H
1. Inverted cusp teeth are easier to set up than cusp teeth. 2. In the use of inverted cusp teeth,
2367
the arrangement (form of occlusion) is optional. There is no restricted prede termined occlusal interdigitation required between the upper and lower teeth as called for with inverted cusp teeth. They may be set lingually or bucally (regular or crossbite), distally or mesially (or thognathic or prognathic case), without consideration of definite interdigital oc clusal relation. The teeth of both the upper and the lower ja w can be set over the ridges, and leverages are thus min imized. 3. In the use of inverted- cusp teeth, increased tongue room is afforded because more cases can be set in crossbite relation. 4. Grinding in the occlusion of the in verted cusp teeth improves their masticat ing efficiency rather than destroys it as is the case with cusp teeth. Extra ma terial is added in the manufacture of inverted cusp teeth for the purpose of allowing for adjustment of the occlusion. 5. Dentures made with inverted cusp teeth are more efficient and require less pressure to effect mastication because of the relatively small occlusal areal con tacts and the sharp scissor-like action of the peripheral edges. 6. Dentures made with inverted cusp teeth function without cusp interference. Tipping and rocking of the dentures is therefore minimized, and trauma, sore ness and tissue change are likewise min imized, w ith the result that the dentures are more comfortable and the duration of service of the dentures is increased. T his eliminates much of the need for rebasing and the construction of new dentures, which is necessary with the use of interlocked cusp teeth. 7. In the use of inverted cusp teeth, relations between the dentures are per mitted to change (reciprocal or compen sating occlusion), as a result of settling
2368
The Journal of the American Denial Association
of the dentures or relationship change be most difficult to accomplish and to main tween the jaws, or both, without pro tain. Dentures are in occlusion today, ducing malocclusion not automatically maybe, and out of occlusion tomorrow. corrected by wear or readjustment co M ake baseplates, trace the gothic arch, incidental w ith any change or not easily register the condyle paths, take test-bites and simply corrected w ith the stone or and check-bites, adjust the facebow, mount the case in the articulator, adjust by mouth grinding. 8. As the last point, but not the least the articulator, grind in the occlusion, important, the use of inverted cusp teeth regrind the occlusion, test the occlusion places denture work on an economical with carbon paper in the mouth, grind and business basis, making it profitable to down the points of interference, cutting both the patient and the dentist. M uch off the cusps w ith the stone in the hand less time is required to make and service piece until they are flat, have the patient dentures w ith the use of inverted cusp chew carborundum, hold the dentures in teeth. place with “corega” or plate powder be T he last fifteen years of my dental cause of looseness as result of tissue activities have been devoted exclusively change, rebase and finally remake the to the one subject, denture prosthesis. I case — such is the denture cycle — and have given the experience gained in these what a nightmare! many years the following name and de Occlusion, the once mystifying, timescription : consuming, inefficient and disappointing T H E D E N TU RE CYCLE part of denture work, is now made sim In practice, occlusion, using inter ple, efficient and satisfactory with the use locked cusp teeth, has been the condition of inverted cusp teeth.
A DENTAL PERSPECTIVE OF THREE HUNDRED FIFTYFIVE CASES OF GASTRIC CARCINOMA* B y HAROLD GOLDSTEIN, D.D.S., Rochester, M inn.
A
SERIES of three hundred and fifty- apical lesions and of periodontal involve five cases of gastric carcinoma in ment, often called pyorrhea. Grading which dental examinations have was done on a basis of 1 to 4, grade 1 been made in the M ayo C linic were denoting the least involvement, and studied. In each case, roentgenograms grade 4, the most extensive involvement. of the entire mouth were taken and care Only cases graded 2 or more, from a ful clinical examinations were made. periapical or periodontal aspect, were re Each case was graded as to degree of garded as sufficiently advanced for con infection from the standpoint of peri sideration. T he accompanying tabulation shows *W ork done in the Section on Dental Sur the incidence by number and percentage gery, the M ayo Clinic.
Jour. A . D. A ., December, 1931
T
H IS paper deals with occlusion in longer retain their finely perfected rela a new, simple and practical manner tions. The case is now a failure, and we free of theories and complicated pro must rebase or remake it, to find that the process merely repeats itself, with the end cedures. It shows the w ay and the means for making more efficient, more comfort result that the patient loses his once w ell able and more nearly permanent dentures, formed, efficient ja w ridges, and is understandable to any dentist and appli thenceforth a dental cripple for life. W ho could be happy in a business— cable to the practice of all. for, indeed, dentistry has a business side After many years’ experience as a practitioner of dentistry, the greater part — delivering to an unsuspecting and of which has been devoted to the specialty trusting public a service so unsatisfac of denture prosthesis, it appeared evident tory? How much better it would be to be to me that the subject, w ith special ref erence to occlusion, was enshrouded in able to make a set of dentures for a much confusion and with many imprac patient that would be efficient and com tical procedures; that, in fact, the dentist fortable, and would be reasonably per was not the master of the subject, but the manent and would preserve the jaw ridges. subject the master of the dentist. The conventional cusp teeth, with In a consideration of occlusion as based their occlusal relations, because of the on the so-called “modern” ideas and interlocked cusps, predetermined and re procedures, results are, on the whole, unsatisfactory and disappointing. The stricted to these relations, are a failure dentures are not efficient nor comfort since they do not provide reciprocal ac able, and they are not so nearly per commodation to compensate for discrep manent as is desirable and possible of ancies arising in their making and for relational changes that occur between the attainment. dentures because of atrophy of the sup B y the time the modern denture can porting tissues, and settling and shifting be made comfortable, the supporting of the dentures. Furthermore, the cusp tissues w ill have become atrophied, which tooth is not efficient because the extent permits relational changes between the and direction of force required to make dentures, and the .whole machine is it so dislodges the dentures and trau thrown out of gear. The once beautifully matizes the supporting tissues. occluded, balanced, interlocking cusps no The secret of the success in eliminating *Read before the Section on Full Dentures at the M idw inter Clinic of the Chicago Den tal Society, Jan . 14, 1930.
Jour. A . D. A., December, 1981
the difficulties enumerated lay in improv ing on the form of tooth employed in denture prosthesis. W ith this thought,
2366
H all— Inverted Cusp Tooth the inverted cusp tooth was conceived and designed. As it is not possible to anchor artificial teeth as natural teeth are anchored in the alveoli of the jaw s to resist the required forces necessary to effect efficient masti cation, it is desirable to provide a form of tooth mechanically suited to the re quirements of the conditions to which it is to be adapted and under which it is to function. There are two points to be considered in the designing of such a tooth: 1. T he cutting, grinding and triturat ing surfaces of the teeth should effect efficient mastication with the minimum amount of muscular force, and direct the forces of mastication favorably to the retention and stabilization of the denture. 2. T he occlusion of the teeth should be reciprocal to compensate for the in evitable relational changes that always occur between the dentures from tissue atrophy and change of jaw relations. The inverted cusp tooth fulfils the foregoing requirements. T he scope of adaptability of the in verted cusp tooth is without lim it. It is equally applicable to all types of cases. It serves in the difficult case in a manner heretofore unequaled, and if used in the more favorable case, it naturally w ill function even better, and w ill insure against the case becoming an “unfavor able” one. T he inverted cusp tooth is not a tooth for the select, difficult case alone, but a tooth for any case-—-a mechanical tooth for artificial use under artificial condi tions. SO M E O F T H E P O IN T S O F A D V A N T A G E I N IN V E R T E D C U S P T E E T H
1. Inverted cusp teeth are easier to set up than cusp teeth. 2. In the use of inverted cusp teeth,
2367
the arrangement (form of occlusion) is optional. There is no restricted prede termined occlusal interdigitation required between the upper and lower teeth as called for with inverted cusp teeth. They may be set lingually or bucally (regular or crossbite), distally or mesially (or thognathic or prognathic case), without consideration of definite interdigital oc clusal relation. The teeth of both the upper and the lower ja w can be set over the ridges, and leverages are thus min imized. 3. In the use of inverted- cusp teeth, increased tongue room is afforded because more cases can be set in crossbite relation. 4. Grinding in the occlusion of the in verted cusp teeth improves their masticat ing efficiency rather than destroys it as is the case with cusp teeth. Extra ma terial is added in the manufacture of inverted cusp teeth for the purpose of allowing for adjustment of the occlusion. 5. Dentures made with inverted cusp teeth are more efficient and require less pressure to effect mastication because of the relatively small occlusal areal con tacts and the sharp scissor-like action of the peripheral edges. 6. Dentures made with inverted cusp teeth function without cusp interference. Tipping and rocking of the dentures is therefore minimized, and trauma, sore ness and tissue change are likewise min imized, w ith the result that the dentures are more comfortable and the duration of service of the dentures is increased. T his eliminates much of the need for rebasing and the construction of new dentures, which is necessary with the use of interlocked cusp teeth. 7. In the use of inverted cusp teeth, relations between the dentures are per mitted to change (reciprocal or compen sating occlusion), as a result of settling
2368
The Journal of the American Denial Association
of the dentures or relationship change be most difficult to accomplish and to main tween the jaws, or both, without pro tain. Dentures are in occlusion today, ducing malocclusion not automatically maybe, and out of occlusion tomorrow. corrected by wear or readjustment co M ake baseplates, trace the gothic arch, incidental w ith any change or not easily register the condyle paths, take test-bites and simply corrected w ith the stone or and check-bites, adjust the facebow, mount the case in the articulator, adjust by mouth grinding. 8. As the last point, but not the least the articulator, grind in the occlusion, important, the use of inverted cusp teeth regrind the occlusion, test the occlusion places denture work on an economical with carbon paper in the mouth, grind and business basis, making it profitable to down the points of interference, cutting both the patient and the dentist. M uch off the cusps w ith the stone in the hand less time is required to make and service piece until they are flat, have the patient dentures w ith the use of inverted cusp chew carborundum, hold the dentures in teeth. place with “corega” or plate powder be T he last fifteen years of my dental cause of looseness as result of tissue activities have been devoted exclusively change, rebase and finally remake the to the one subject, denture prosthesis. I case — such is the denture cycle — and have given the experience gained in these what a nightmare! many years the following name and de Occlusion, the once mystifying, timescription : consuming, inefficient and disappointing T H E D E N TU RE CYCLE part of denture work, is now made sim In practice, occlusion, using inter ple, efficient and satisfactory with the use locked cusp teeth, has been the condition of inverted cusp teeth.
A DENTAL PERSPECTIVE OF THREE HUNDRED FIFTYFIVE CASES OF GASTRIC CARCINOMA* B y HAROLD GOLDSTEIN, D.D.S., Rochester, M inn.
A
SERIES of three hundred and fifty- apical lesions and of periodontal involve five cases of gastric carcinoma in ment, often called pyorrhea. Grading which dental examinations have was done on a basis of 1 to 4, grade 1 been made in the M ayo C linic were denoting the least involvement, and studied. In each case, roentgenograms grade 4, the most extensive involvement. of the entire mouth were taken and care Only cases graded 2 or more, from a ful clinical examinations were made. periapical or periodontal aspect, were re Each case was graded as to degree of garded as sufficiently advanced for con infection from the standpoint of peri sideration. T he accompanying tabulation shows *W ork done in the Section on Dental Sur the incidence by number and percentage gery, the M ayo Clinic.
Jour. A . D. A ., December, 1931