Cusp Height Research Articles

Measurement of cusp height and ridge and groove direction using an electrical transducer. Part I: Instrumentation

Measurement of cusp height and ridge and groove direction using an electrical transducer. Part I: Instrumentation

The effect of reducing cusp height on the rate of approximal drift of cheek teeth in adult monkeys ( Macaca irus)

The cusps of cheek teeth were reduced in height on one side of the mouth in six adult males. Approximal migration was significantly more rapid in the first two to three weeks than on the side with intact cusps. The effect became less evident after longer periods. It is concluded that interdigitation of cusps during normal function tends to retard experimental approximal drift.

Minor congenital variations of cusp size in tricuspid aortic valves. Possible link with isolated aortic stenosis.

Clinically isolated aortic stenosis is most commonly caused by a congenitally malformed aortic valve. Many elderly patients with isolated aortic stenosis have a tricuspid aortic valve. It has been suggested in the past that inequalities in individual cusp size could be a factor leading to the development of the stenoses in these cases. In this study the width and height of individual aortic valve cusps were measured at necropsy in 200 hearts of patients without clinical signs of aortic stenosis, though the majority of valves obtained from elderly persons showed some ageing changes. The results were compared with similar measurements in 16 hearts of patients with clinically diagnosed and necropsy proven isolated aortic stenosis. The results show that inequality in cusp size is the rule rather than the exception. Indeed, only 5 of the 200 'normal' tricuspid aortic valves had 3 cusps of identical height and width, and each of the 16 cases with isolated aortic stenosis has cusps of differing size. The results seem to contradict the aforementioned hypothesis. However, the striking similarities between isolated aortic stenosis and the ageing aortic valve, suggest that isolated tricuspid aortic stenosis is an extreme with a spectrum of ageing alterations. Inequality in cusp size, with differences in mechanical tissue stress as a consequence, could then play a role in the pathogenesis of the stenosis by accelerating the ageing process.

Application of “cusp writer” findings to practical and theoretical occlusal problems. Part II

The cusp writer is a teaching aid to facilitate understanding of the correlation between cusp angulations and the various occlusal determinants. The cusp writer provides graphic evidence that the occlusal determinants which influence configurations (i.e., incisal guidance, condylar guidance, plane [curve] of occlusion, curve of Spee [compensating curve], and plane of motion) are reciprocal, one tempering the value of the other. Cusp writings demonstrate the following: (1) The angle of the plane (curve) of occlusion to the plane of motion in concert with the other occlusal infuluence determines the optimal height and angulation of the cusps. (2) Cusps appear to be steep or shallow relative to each other, to the plane of occlusion, and to the plane of motion. (3) The steepness of the curve of Spee determines the relative cusp height and angulation of one tooth to another, from an anterior to a posterior direction in the dental arch. (4) The angle of the tangent to any segment of the curve of Spee to the plane of motion determines the optimal height and angulation of the cusps of the segment. (5) The graphs show that the flatter the curve of Spee, the more uniform the cusp height and angulations are from anterior to posterior teeth. The steeper the curve of Spee, the more irregular the cusp height and angulations are with steeper anterior cusps and flatter posterior cusps. (6) The steeper the curve of Spee, the flatter the molar cusp angulations must be to avoid deflective and/or interceptive occlusal contacts on the balancing side. (7) With the syndrome of a steepening curve of Spee due to the loss of one or more lower posterior teeth, the cusps of the remaining opposing teeth must be constantly flattened by wear or selective grinding and reshaping to avoid traumatic occlusion, unless the drifting is interrupted by restorative dentistry. (8) Cusp angulation of artificial teeth should be chosen to harmonize with the angle of incidence of the compensating curve tangents to the plane of motion. (9) Condylar guidance has less influence on cusp angulation in comparison to incisal guidance and the other occlusal determinants. (10) Changing the hinge axis location 1/2 inch (12.5 mm.) distally and/or superiorly has very little effect on the influence of the above occlusal determinants on cusp configuration, if the vertical dimension of occlusion remains constant.

Canine role in dental wear patterns: Macaca nemestrina

AbstractA study of variables and patterns in dental wear among 30 individuals in a colony of Macaca nemestrina shows that consideration of age and sex are crucial for understanding differential wear degrees on molar occlusal planes. With advanced age, this species of non‐human primate undergoes obliteration of initial morphological characteristics through the gradual erosion of enamel. Wear gradients are differential from PM1‐M3 in both sexes. It appears that there is a functional relationship between degrees of occlusal plane wear and the degree of wear on the canines, and that females show a greater degree of wear changes relative to males of equivalent age because of initial differences in canine length and robusticity due to sexual dimorphism. It appears that there is a direct relationship between occlusal wear plane changes and the degree of wear on the canines, with advanced differential wear showing up in individuals in whom years of maxillary canine honing, canine damage, and the normal wear of mastication has reduced dimensions of unworn permanent canines. Other considerations included in this study are the honing functions of the deciduous first mandibular molars and molar cusp height relative to canine function.

Masticatory function and oral rehabilitation.

SummaryExamination of many different animal dentitions suggests that in those whose function is mastication rather than merely prehension, tooth wear is not only normal but essential to achieve full efficiency. A similar character is found in man among Eskimos and Aborigines where these people live on completely natural diets, and also in Anglo‐Saxon skulls. It is suggested that attrition should be a normal process in the human dentition, and compensatory mechanisms for the loss of tooth substance are discussed. The significance of the unworn cusp in relation to dental and other diseases of Western civilisation is considered, together with the suggestion that sufficient evidence now exists to justify simple cusp height reduction as a prophylactic measure.

Controlled functional waxing instrumentation for fixed occlusal reconstruction

A method of controlling the waxing of a posterior occlusal reconstruction has been described. This method produces an occlusal scheme which has a common Curve of Spee and Wilson on a plane of occlusion which has common arcial central fossae, cusp heights and inclination of buccolingual grooves, and marginal ridge heights. This procedure develops an occlusal morphology to which an opposing occlusal functional reconstruction can be made.

Relative growth within the human first upper permanent molar during the prenatal period

Twelve measurements were made on each of thirty-one developing human M 1 tooth germs: width across the mesial and distal parts of the crown; length of the buccal and lingual portions of the tooth; height of buccal cusps; diameters of buccal and lingual root openings; distance between the tips of the main cusps. Double logarithmic plots were made against mesial width and regression coefficients calculated. No change in slope was detected at the initiation of calcification. Regression against foetal age also showed no change of specific growth rate at this time, but very young specimens (< 25 weeks) had a higher growth rate. Significant differences in the specific growth rates of various measurements were found: the tooth grows faster in length than in width, and its distal portion grows faster than its mesial portion. Paracone height grows at the same rate as mesial crown width. The highest growth rates found were those of the intercuspal distances, the lowest those of the diameters of the root openings.

An evaluation of basic articulators and their concepts: Part III. Fully adjustable articulators

Many dentists eliminate tooth contacts on the balancing side in fixed restorative work. In view of this, a true perspective of the value of the instrument can be seen. The maximum total error at the second molar cusp height on the working side is only 0.2 mm. Therefore, the instrument has real practical value for fixed restorative dentistry on the condition that it accepts the lateral interocclusal records. The percentage of records that the instrument will accept has not been determined.

Occlusion as it relates to fixed restorations

1. The longevity of fixed restorations depends upon bone support as much as any other one factor. However, the metabolic activity of the bone for each patient is different. Recognition of this variation eliminates many errors in the diagnosis, treatment planning, and prognosis of dental restorations. 2. An attempt to alter the existing interocclusal distance should be approached with caution. All available methods, including tracings of cephalometric roentgenograms, should be employed to accurately determine the amount of this space between the teeth in rest position. 3. Worn-out dentitions require that the functional surfaces of cusps be developed with a parabolic form if that dentition is to take its place as an efficient organ of a healthy masticatory system. 4. The cusps of dental restorations which will maintain functional equilibrium in the patient's mouth are dependent upon the condylar guidance, incisal guidance, plane of occlusion, Spee's curve, and cusp height. The influence of each of these factors was discussed. 5. An adjustable anatomic articulator is an indispensable tool in the development of functional occlusal surfaces. However, the results will be only as good as the thinking of the dentist who uses the instrument. 6. The value of the hinge axis determination was discussed, as well as the necessity for harmony between centric relation and centric occlusion. All deflective occlusal contacts must be removed before fixed restorations are placed in the existing occlusion. 7. Dental restorations must be developed from a dynamic point of view. This includes the straight protrusive, lateral protrusive, and lateral excursive movements of the mandible. 8. A technique for the generation of the occlusal surfaces of wax patterns that will be in functional occlusion for each individual patient has been described. 9. A thorough knowledge of the subject of functional occlusion without any preconceived ideas and an ability to apply sound biologic principles to methods of treatment will consistently produce fixed restorations of the highest degree of perfection.

Discussion of “laws of articulation”

I agree in part with both Hanau's and Trapozzano's concepts of the laws of occlusion. 1. I see three fixed factors instead of one, with the orientation of the occlusal plane and the incisal guidance angle being additions to the condylar guidance as fixed factors. 2. The angulation of certain cuspal inclines is more important than the height of the cusps per se. 3. The compensating curve is a device for increasing the effective height of the cusps without changing the forms of the individual teeth. 4. Both the cusp height and the compensating curve are means for solving the problems imposed by the Christensen phenomenon. They are the means whereby the space developed at the posterior end of the occluding surfaces which results from the downward movement of the condyles can be closed by tooth contacts. 5. The occlusal plane should be oriented according to esthetic appearance and intraoral soft tissue anatomy (the retromolar pads and tongue) instead of located according to leverage or mechanical requirements. 6. The orientation of the occlusal plane, i.e., the angle of its deviation from the horizontal, does have an effect upon the things that must be done to the angulation of the cuspal inclines, either by tipping the teeth into a compensating curve or the choice of a posterior tooth form. 7. Dr. Trapozzano's diagram can be helpful toward an understanding of the relationship of the tooth surfaces to the end guidances. In closing, I wish to thank Dr. Trapozzano for stimulating me to put these ideas on paper. I feel certain that he has stimulated the reader as well.

Application of miniaturized electronic devices to the study of tooth contact in complete dentures: A progress report

A method has been developed for incorporating radio transmitters into complete dentures for the study of masticating and nonmasticating contacts of the occlusal surfaces. Both fixed and portable equipment may be used to record these contacts in the laboratory and during normal activities at any time. In the pilot study outlined on 2 patients, patient A exhibited few and fleeting contacts of the teeth in chewing. Patient B exhibited a great deal of tooth contact in chewing most foods. The number and character of the contacts were influenced by the type of cusp form and the harmony of balanced occlusion. The signal came from the cusp height as well as from the centric relation-centric occlusion position. The potentiality of this method in dental research will be greater as new electronic devices are perfected.

Vertical Dimension, Jaw Relation Records and Occlusion

The problems of vertical dimension, jaw relation records and occlusion are complex, and they involve a complete study of what is commonly called the stomatognathic system. There are many methods available for the determination of the correct vertical dimension. Some are dependent on measurements, some on phonetics, others on cephalometrics and still others on tactile sense. The reliability of any of these methods may be questioned because there is no scientific proof of their accuracy, but their true value lies in the fact that they are aids which will help to resolve the problem of vertical dimension. Free-way space and physiologic rest position are the most sought-after aids in the establishment of the desirable vertical dimension for the edentulous patient. The use of jaw relation records is predicated on the fact that the maxillary cast has been properly oriented to the articulator so that the maxillary cast has the same relation to the temporomandibular articulation as it does in the mouth. This is accomplished through the use of the facebow. Jaw relation records generally fall into two main classifications, the interocclusal method and the tracing device method. To obtain the most accurate results from either method necessitates a knowledge of their limitations, advantages, and disadvantages. The complexity of the problem of occlusion has been stressed. The more important factors in the development of the occlusal scheme have been emphasized. Some of the more important points are these: 1. The movements of the temporomandibular articulation are many and varied. 2. The muscles of the body, to be in a state of equilibrium, must be at their true physiologic resting position or in a state of isotonic contraction. 3. Vertical dimension of rest and vertical dimension of occlusion are not one and the same. 4. The composition of bone is such that it cannot withstand a sustained force. Dentures must be constructed with a separation of the teeth when the mandible is at rest, and the teeth must be so positioned as to create forces of occlusion that are favorable to the bone, to prevent rapid resorption. 5. The plane of occlusion should be so positioned that favorable leverages will be exerted on both arches. 6. Centric relation and the hinge axis are considered a terminal position, but to call the rest relation a terminal position would be incorrect. 7. Centric relation is found at the apex of the needlepoint tracing. Patients may also have formed a habit, or functional relationship. With patients who have an acquired or functional eccentric relationship it is not advisable to lock the occlusion to the apex. This may be accomplished by allowing the teeth to gain an additional range of horizontal movement without engaging the inclined planes. 8. Cusp teeth, with their thickness of occlusal pattern and cuspal inclinations, lend themselves well to the establishment of occlusal balance and the reduction of traumatic forces to the underlying bone. 9. Flat teeth, lacking cusp height and inclination, will not be a factor in the reduction of trauma in denture construction. 10. Balanced occlusion means an equalized contact between masticating surfaces within their functional range, which will include centric and eccentric movements. 11. The eccentric movements of the mandible are controlled by condylar guidance, incisal guidance and Bennett movements. 12. The balancing factors for eccentric movements are the plane of orientation, compensating curve, cusp height and inclination. 13. Each patient is an individual in regard to age, sex, physical, mental, and physiologic factors. This obviously means that no one stereotyped pattern of tooth with an arbitrary degree of cuspal inclination will satisfy the needs of all patients.

大分県杵築市女の歯牙彎曲、口蓋と歯列弓形態の研究

Morphological patterns of the occlusion curve, the palate and the dental arch occurring in the female population in Kitsuki city, Oita prefecture were studied on the gnathostatic models which were mounted on the eye-ear planes as bases, and the data obtained were comapred with those obtained from the female in Yawata city, the male and female in Shimonoseki city, the Japanese male and the Manchurian male. The results are summarized as follows. 1) Regulative curve of dental arch In upper jaw the central incisors are the highest from the eye-ear plane, the height decreasing gradually with successive teeth backward. The lower jaw shows a curve similar to the regulative curve of upper jaw against the eye-ear plane. 2) Comparison of the height of individual teeth measured from the eye-ear plane between the female in Kitsuki and the male in Manchuria revealed that there is hardly any difference present with respect to upper jaw, whereas with respect to lower jaw the height in Manchurian male is greater than that in Kitsuki female. 3) In the lateral curve of upper molars in Kitsuki female, it was noticed that the height of buccal cusp of first and second premolars is higher than that of palatal cusps, whereas in the first and second molars the latter cusps are higher than their opponents. However, there is not found any significance of difference in heights of the buccal and palatal cusps of these teeth. 4) The highest point from the eye-ear plane to the curve of median sagittal plane lies on the prosthion with distance of 51mm, the height of the curve becoming gradually lower as it goes farther away from the orbito-sagittal point till it is lowest with distance of 32mm on the average at the point 30mm distant from the orbito-sagittal point (Fig.3). 5) In the comparison on the height from the eye-ear plane to the curve of median sagittal plane of palate between the female in Kitsuki and the male in Manchuria, the height in the former proved higher than that in the latter group. 6) Of the heights from the eye-ear plane to the palatal arch curve examined in the female of Kitsuki, the height at the center is lowest with 32mm on the average and those at both anterior and posterior ends are 45mm on the average, and the curve is of the parabolic type (Fig.4). 7) Comparison between the female in Kitsuki and the Manchurian male on the height from the eye-ear plane to the palatal arch curve does not show any appreciable difference. 8) The degree of incisal occlusion examined on the female in Kitsuki is 3mm on the average which is shown to be smaller than the values obtained for the female in Yawata, the female and male in Shimonoseki and the Japanese and Manchurian male. 9) The over-bite degree examined on the female in Kitsuki is 4mm on the average which is shown to be larger than those values obtained for the Yawata female, Shimonoseki male and female, and for the Manchurian male. 10) The average values for the breadth of dental arch at canine tooth region examined on the Kitsuki female are respectively 35mm in upper jaw, 27mm in lower jaw, and those at the anterior tooth region are respectively 49mm in upper jaw, 43mm in lower jaw, showing relative larger values with upper jaw in every cases. 11) The dental arch breadth or the Kitsuki female is larger than that of the Yawata female, approximately identical with that of the Shimonoseki female, and is smaller than those of the Japanese male and of the Manchurian male. 12) The average values for the anterior dental arch in the Kitsuki female are respectively 18mm in upper jaw, 13mm in lower jaw ; the same values for the posterior dental arch are respectively 32mm in upper jaw, 27mm in lower jaw, indicating that both lengths are larger in upper jaw than in lower jaw. 13) The length of dental arch in the Kitsuki female is larger than that in the Yawata female, approximately the same with those in the Shimonoseki male and female, and smaller

齒牙各咬頭頂と補綴學的平面との位置的關係に就いて : スピー氏彎曲の臨床的觀察

When the artificial full denture be made for the purpose of reconstructing the lost function of patient's mastication and speech or his appearance, care must be taken of the fact that we are dealing with a living body which differs racially in topographic anatomical details. The author made the measurements on one hundred individuals of the various distances from the occlusal plane to each cusp of lower teeth and found that the occlusal plane established hypothetically by Dr. Gysi would be inapplicable for the Japanese jaws. The measurements showed that the lowest point in dental arch should fall on the contact point between the lower second bicuspid and first molar. It was also shown that the height of buccal cusp of second bicuspid came to the height of mucous rise at the glandula retro molare which is said to keep well its previous level even in edentulous jaw. In view of these findings the author think it advisable in arranging the artificial teeth that the disto-buccal cusp of extreme molar be posed at the same height with the posterior margin of trial base plate so as to keep the denture in the natural anatomical position and to reproduce in it the harmonious ralationship between cusps and tongue.