Guidance Angle Research Articles

Comparative analysis of sagittal condylar guidance by protrusive interocclusal records with panoramic and lateral cephalogram radiographs in dentulous population: A clinico-radiographic study.

Aim:To evaluate and compare the correlation between sagittal condylar guidance obtained by protrusive interocclusal records mounted on semi-adjustable articulator with panoramic and Lateral cephalogram radiograph tracings in dentulous population.Materials and Methods:One-hundred twenty dentulous subjects between age group of 20–40 years, free of signs and symptoms of any temporomandibular diseases were selected. The sagittal condylar guidance was determined by protrusive interocclusal records and transferred to a semi-adjustable articulator through a face bow. The condylar guidance angles obtained were tabulated. The sagittal outline of the articular eminence and glenoid fossa were traced on panoramic and lateral cephalogram radiographs. The sagittal condylar path inclination was constructed. This was related to the Frankfurt's horizontal plane on radiograph to determine the radiographic angle of sagittal condylar guidance. The comparison of protrusive interocclusal records was done with the angles obtained by panoramic and lateral cephalogram radiograph tracings.Results:The mean difference between the condylar guidance values obtained using panoramic and lateral cephalogram radiographs was 0.13° and 0.67° on right side and 1.0° and 1.54° on left side with the radiographic values being higher. A Significant positive correlation was observed with P values 0.001 and 0.005 in left and right respectively.Conclusion:This study highlighted on the correlation between protrusive interocclusal records and the lateral cephalogram radiograph tracings which were more positively related than the panoramic radiograph. The values of lateral cephalogram radiograph tracings are closer as separate radiographs for left and right side were taken, causing the amount and quality of image distortion less. Lateral cephalogram radiograph may be taken as an important tool to rely on for recording the Sagittal condylar guidance angle.

An in vivo study to compare and correlate sagittal condylar guidance obtained by radiographic and extraoral gothic arch tracing method in edentulous patients

Purpose: To compare the sagittal condylar guidance angle obtained by extra oral gothic arch tracing and orthopantomogram in completely edentulous subjects. Material and Methods: Ten completely edentulous subjects were selected by the inclusion and exclusion criteria. Conventional steps in the fabrication of complete denture with balanced occlusion were carried out. Extra oral gothic arch tracing records were obtained for every patient. Protrusive interocclusal records were used to program the Hanau wide vue semiadjustable articulator, thus obtaining the sagittal condylar guidance angle by clinical method. On the orthopantomogram obtained for every patient in the study, orbitale and porion were located and the Frankfurts horizontal reference line was drawn. The most superior and the inferior points on the glenoid fossa curvature were located and a mean curvature line was obtained. A third reference line passing through the most superior and the inferior points on the glenoid fossa was extended to intersect the Frankfurts horizontal plane, thus obtaining the radiographic sagittal condylar guidance. These values were tabulated and subjected to Wilcoxon Signed Ranks test. Results: There is statistically significant difference between the sagittal condylar guidance values obtained between right and left sides with extra oral gothic arch tracing and orthopantomographic method (p value is 0.014 and 0.007 respectively). Conclusions: The use of orthopantomogram to set the condylar guidance on the semi adjustable articulator for complete denture therapy is questionable.

Local reactive obstacle avoidance approach for high-speed unmanned surface vehicle

Unmanned surface vehicles (USVs) are important autonomous marine robots that have been extensively studied and gradually applied. However, the autonomy of USVs is still restricted by the performance of autonomous navigation technology. At present, various local obstacle avoidance algorithms have been proposed for USVs. However, the majority of algorithm results have only been verified by simulations, with only a few demonstrated by low-speed USVs (≤5 knots) in the sea. Therefore, the issues of obstacle avoidance for high-speed USVs in complicated obstacles environments have to be studied. This paper presents a novel general local reactive obstacle avoidance algorithm for high-speed USVs. In this algorithm, the direction steady-state model and the translational velocity model are proposed for the base normal motion and base motion control characteristics of high-speed vessels. During navigation, USV motion depends on the guidance angle and guidance translational velocity. The validity of the proposed algorithm is verified by experiments in simulations and sea trials on a high-speed USV (≥20 knots) in real marine environments. Results show that the algorithm adapts to the characteristics of high-speed USVs and can guide high-speed USVs (≥20 knots) in realizing safe navigation in real marine environments.

Relationship between jaw movement and masticatory performance in adults with natural dentition

Objective. This study determines the relationship between several characteristics of jaw movement and masticatory performance determined by multiple regression analysis and adjusted for occlusal contact area and bite force. Materials and methods. Forty-two young adults with natural dentition participated in this cross-sectional study. Occlusal contact area was determined at the maximum intercuspal position by scanning interocclusal records. Maximum unilateral force was measured by means of a gnathodynamometer. The height and amplitude of mastication, occlusal glide length, lateral guidance angle, anterior–posterior distance and cycle duration were recorded using the ARCUSdigma II system. Masticatory performance was determined by sieving the Optosil particles resulting from 20 chewing cycles. Results. Median particle size was negatively associated with height of mastication, maximum bite force, occlusal contact area and amplitude of mastication. Stepwise multiple linear regression analysis revealed that the height of mastication and dental guidance angle are the characteristics of jaw movement most closely related to masticatory performance. Conclusions. In adults with natural dentition, a large vertical height of mastication and a small dental guidance angle are the characteristics of jaw movement most closely associated with good masticatory performance, determined by multiple regression analysis and adjusted for occlusal contact area and bite force.

Assessment of the repeatability of condylar guidance angles obtained from panoramic radiographic images

Assessment of the repeatability of condylar guidance angles obtained from panoramic radiographic images

A Comparative Evaluation of Condylar Guidance Value from Radiograph with Interocclusal Records made During Jaw Relation and Try-in: A Pilot Study.

The purpose of this study was to evaluate the reliability of programming the articulator using the radiographs and the interocclusal records made during Jaw relation (Arrow point tracing) and Try-in stage. The study comprised of 15 edentulous subjects with well formed maxillary and mandibular ridges, with no signs and symptoms of temporomandibular joint disorders and neuromuscular disorders. Digital Orthopantomograph was taken for all the subjects. The condylar guidance angles were traced on Orthopantomograph for right and left sides and the values were recorded. The protrusive interocclusal records were made at jaw relation stage and at try-in stage using bite registration paste (Bitrex- vinyl polysiloxane) for all subjects. These interocclusal records were used to programme the Semi-adjustable articulator (Hanau Wide Vue) and the condylar guidance values on the right and left sides were recorded. The condylar guidance values so obtained were compared with the values obtained by Orthopantomograph. The condylar guidance values obtained by the various procedures were subjected to statistical analysis. The results showed statistically significant difference between the condylar guidance values obtained from Orthopantomograph (Radiograph) and the condylar guidance values obtained at the stage of jaw relation and also between Orthopantomograph and condylar guidance values obtained at the stage of Try-in. Condylar guidance values obtained from the Radiographs were higher than those obtained at the stage of Jaw relation and at the stage of Try-in. However, we notice that the mean condylar guidance values obtained at the stage of Try-in were nearer to the mean condylar guidance values obtained on the Radiographs.

Temporomandibular Disorders: The Habitual Chewing Side Syndrome

BackgroundTemporomandibular disorders are the most common cause of chronic orofacial pain, but, except where they occur subsequent to trauma, their cause remains unknown. This cross-sectional study assessed chewing function (habitual chewing side) and the differences of the chewing side and condylar path and lateral anterior guidance angles in participants with chronic unilateral temporomandibular disorder. This is the preliminary report of a randomized trial that aimed to test the effect of a new occlusal adjustment therapy.MethodsThe masticatory function of 21 randomly selected completely dentate participants with chronic temporomandibular disorders (all but one with unilateral symptoms) was assessed by observing them eat almonds, inspecting the lateral horizontal movement of the jaw, with kinesiography, and by means of interview. The condylar path in the sagittal plane and the lateral anterior guidance angles with respect to the Frankfort horizontal plane in the frontal plane were measured on both sides in each individual.ResultsSixteen of 20 participants with unilateral symptoms chewed on the affected side; the concordance (Fisher’s exact test, P = .003) and the concordance-symmetry level (Kappa coefficient κ = 0.689; 95% confidence interval [CI], 0.38 to 0.99; P = .002) were significant. The mean condylar path angle was steeper (53.47(10.88) degrees versus 46.16(7.25) degrees; P = .001), and the mean lateral anterior guidance angle was flatter (41.63(13.35) degrees versus 48.32(9.53) degrees P = .036) on the symptomatic side.DiscussionThe results of this study support the use of a new term based on etiology, “habitual chewing side syndrome”, instead of the nonspecific symptom-based “temporomandibular joint disorders”; this denomination is characterized in adults by a steeper condylar path, flatter lateral anterior guidance, and habitual chewing on the symptomatic side.

Relationship between the Preferred Chewing Side and the Angulation of Anterior Tooth Guidance

Objectives: The aim of this study was to evaluate a possible relationship between preferred chewing side (PCS) and the anterior guidance angle. Subjects and Methods: Forty dental nurses and technicians, aged 24-46 years, were each given a piece of chewing gum, which they chewed for about 3 min. At 7 regular intervals (every 15 s), they were interrupted by the principal investigator (P.L.) in order to observe on which side of their mouths they had the bolus of chewing gum. Moulds of their jaws were made and the position of the maxillary arch relative to temporomandibular joints was recorded with a facebow and transferred to a semi-adjustable articulator. After mounting the stone casts of each subject, a measure of the anterior guidance angle was taken with an adjustable incisal table. Results: Of the 40 subjects, 14 (35%) presented a PCS. Among the 14 subjects who preferred a chewing side, there was a correlation between the PCS and a low angulation of teeth constituting the anterior guidance on that side, but this correlation was statistically nonsignificant. Conclusion: In this study, we found that unilateral chewing creates uneven wear on the anterior teeth and changed the anterior guidance angulation.

A Comparative Evaluation of Static and Functional Methods for Recording Centric Relation and Condylar Guidance: A Clinical Study

To evaluate and compare the centric relation and horizontal condylar guidance using interocclusal wax and extra oral Gothic arch methods and subjective evaluation of dentures thus fabricated. Centric relation and horizontal condylar guidance was recorded by using interocclusal wax and gothic arch tracing in 28 completely edentulous patients. These records were transferred to the articulator and difference in both values was recorded. After that patients were divided in two groups according to the centric relation and horizontal condylar guidance recording method used to achieve balanced occlusion. Response of the dentures was subjectively evaluated using "Woelfel subjective evaluation criteria". Centric relation recorded by both the methods did coincide in 7.14% of patients. Centric relation recorded by interocclusal wax was posterior to Gothic centric relation in 21.43% of patients, and anterior to Gothic centric relation in 71.42% patients. Gothic arch tracings gave higher mean guidance values on both the sides as compared to protrusive wax record in all the subjects, although the difference was statistically insignificant (P>0.05). Subjective evaluation showed statistical insignificance for all the parameters in both groups. Gothic arch method records the centric relation at a more posterior position than the Static method, but it does not make any difference in clinical performance of the complete denture. Horizontal condylar guidance angle was approximately similar by both the methods.

Condylar Guidance: Correlation between Protrusive Interocclusal Record and Panoramic Radiographic Image: A Pilot Study

The purpose of this study was to compare the sagittal condylar angles set in the Hanau articulator by use of a method of obtaining an intraoral protrusive record to those angles found using a panoramic radiographic image. Ten patients, free of signs and symptoms of temporomandibular disorder and with intact dentition were selected. The dental stone casts of the subjects were mounted on a Hanau articulator with a springbow and poly(vinyl siloxane) interocclusal records. For all patients, the protrusive records were obtained when the mandible moved forward by approximately 6 mm. All procedures for recording, mounting, and setting were done in the same session. The condylar guidance angles obtained were tabulated. A panoramic radiographic image of each patient was made with the Frankfurt horizontal plane parallel to the floor of the mouth. Tracings of the radiographic images were made. The horizontal reference line was marked by joining the orbitale and porion. The most superior and most inferior points of the curvatures were identified. These two lines were connected by a straight line representing the mean curvature line. Angles made by the intersection of the mean curvature line and the horizontal reference line were measured. The results were subjected to statistical analysis with a significance level of p < 0.05. The radiographic values were on average 4° greater than the values obtained by protrusive interocclusal record method. The mean condylar guidance angle between the right and left side by both the methods was not statistically significant. The comparison of mean condylar guidance angles between the right side of the protrusive record method and the right side of the panoramic radiographic method and the left side of the protrusive record method and the left side of the panoramic radiographic method (p= 0.071 and p= 0.057, respectively) were not statistically significant. Within the limitations of this study, it was concluded that the protrusive condylar guidance angles obtained by panoramic radiograph may be used in programming semi-adjustable articulators.

A clinico-radiographic analysis of sagittal condylar guidance determined by protrusive interocclusal registration and panoramic radiographic images in humans

Purpose:To evaluate the correlation between sagittal condylar guidance obtained by protrusive interocclusal records and panoramic radiograph tracing methods in human dentulous subjects.Materials and Methods:The sagittal condylar guidance was determined in 75 dentulous subjects by protrusive interocclusal records using Aluwax through a face bow transfer (HANAU™ Spring Bow, Whip Mix Corporation, USA) to a semi-adjustable articulator (HANAU™ Wide-Vue Articulator, Whip Mix Corporation, USA). In the same subjects, the sagittal outline of the articular eminence and glenoid fossa was traced in panoramic radiographs. The sagittal condylar path inclination was constructed by joining the heights of curvature in the glenoid fossa and the corresponding articular eminence. This was then related to the constructed Frankfurt's horizontal plane to determine the radiographic angle of sagittal condylar guidance.Results:A strong positive correlation existed between right and left condylar guidance by the protrusive interocclusal method (P 0.000) and similarly by the radiographic method (P 0.013). The mean difference between the condylar guidance obtained using both methods were 1.97° for the right side and 3.18° for the left side. This difference between the values by the two methods was found to be highly significant for the right (P 0.003) and left side (P 0.000), respectively. The sagittal condylar guidance obtained from both methods showed a significant positive correlation on right (P 0.000) and left side (P 0.015), respectively.Conclusion:Panoramic radiographic tracings of the sagittal condylar path guidance may be made relative to the Frankfurt's horizontal reference plane and the resulting condylar guidance angles used to set the condylar guide settings of semi-adjustable articulators.

Midline shift and lateral guidance angle in adults with unilateral posterior crossbite

Unilateral posterior crossbite is a malocclusion that, if not corrected during infancy, typically causes permanent asymmetry. Our aims in this study were to evaluate various occlusal parameters in a group of adults with uncorrected unilateral posterior crossbite and to compare findings with those obtained in a group of normal subjects. Midline shift at maximum intercuspation, midline shift at maximum aperture, and lateral guidance angle in the frontal plane were assessed in 25 adults (ages, 17-26 years; mean, 19.6 years) with crossbites. Midline shift at maximum intercuspation was zero (ie, centric midline) in 36% of the crossbite subjects; the remaining subjects had a shift toward the crossbite side. Midline shift at maximum aperture had no association with crossbite side. Lateral guidance angle was lower on the crossbite side than on the noncrossbite side. No parameter studied showed significant differences with respect to the normal subjects. Adults with unilateral posterior crossbite have adaptations that compensate for the crossbite and maintain normal function.

Association of the canine guidance angle with maxillary and mandibular intercanine widths and anterior alignment relapse: Extraction vs nonextraction treatment

Long-term stability is an important measure of the success of orthodontic treatment. Research in the 1970s suggested that premolar extraction treatment had poor stability over the long term. The purpose of this prospective follow-up study was to investigate changes in intercanine widths and the irregularity index during the postretention phase in patients treated with and without extractions. Associations between the maxillary canine guidance angle and the mandibular intercanine widths and the mandibular irregularity index were also examined. Two groups of 30 patients each, with and without premolar extractions, were studied and the results compared. Records were taken at pretreatment, at bracket removal, at the end of retention, and out of retention. The times out of retention were 6.3 years for the nonextraction group and 6.5 years for the extraction group. Stone casts were mounted on an articulator with an anatomical facebow and a central wax record. The measurements were made with a 3-dimensional digitizer. Maxillary and mandibular intercanine distances behaved differently. The mandibular intercanine distance showed a net decrease between pretreatment and follow-up, whereas the maxillary arch had a net increase. The maxillary canine guidance angle at the end of retention, measured to the axis-orbital plane, was highly associated with relapse of mandibular anterior alignment and change of the mandibular intercanine distance. Methods are needed that consider the anatomical configuration of the teeth for bracket selection before treatment. Individualized brackets (torque) should then be coordinated with the guidance angle of the maxillary teeth.

The third point of reference and its effect on the protrusive condylar guidance angles obtained in semi-adjustable articulator

Context: Clinicians have questioned the transferability of occlusal plane relationship from the patient to the articulator when Orbitale was used as anterior point of reference for the facebow transfer. Aims: The aim of this study was to evaluate the effect of 4 different anterior reference points on the protrusive condylar guidance angles in using an articulator. Settings and Design: Twelve dentate patients were selected for the study. Hanau Wide Vue (No. 183, Teledyne Water Pik, Fort Collins, Colorado, USA) and corresponding SpringBow (Teledyne Water Pik, Fort Collins, Colorado, USA) were used in the study. Materials and Methods: Four maxillary casts were obtained for each patient and mounted on a Hanau Wide Vue articulator with the help of a SpringBow using Orbitale, Orbitale minus 7 mm, and the inferior and superior annular notches of the articulator incisal guide pin as four points of references. The mandibular casts were hand articulated in the maximum intercuspal position. Protrusive records were made using Polyether Bite Registration material (Ramitec, 3M ESPE, St. Paul, MN), and the articulator was programmed for all the 4 mountings in each patient. The protrusive condylar path angles to Frankfort plane were obtained from lateral cephalometric tracings made in maximum intercuspation and protrusive position for comparison. Statistical Analysis Used: Statistical analysis was done using paired t test and Wilcoxon's signed rank test ( P < 0.05) to make a comparison between the protrusive condylar guidance angles obtained from the interocclusal records with the mountings using 4 different third points of references and those of radiographic tracings. Results: The protrusive condylar guidance values obtained on the casts related to the third point of reference with the superior annular notch and Orbitale minus 7 mm reference points differed significantly from the radiographic values ( P < 0.05). The mean protrusive condylar guidance angles differed from the mean radiographic values in an ascending order: inferior annular notch (-2.4 degrees), Orbitale (5.2 degrees), Orbitale minus 7 mm (13.1 degrees), and superior annular notch (17.0 degrees) respectively ( P < 0.05). The protrusive condylar guidance registrations for the right and the left sides on the casts related to the third point of reference with Orbitale (R = 41.8 degrees and L = 36.9 degrees) and inferior annular notch (R = 49.4 degrees and L = 44.8 degrees) were found to be closer to radiographic values (R = 47.0 degrees and L = 41.0 degrees) ( P < 0.05). Conclusions: Within the limitations of this study, the Orbitale and inferior annular notches were found to be more accurate anterior points of references than the superior annular notch and Orbitale minus 7 mm reference points to mount the casts in Hanau Wide Vue articulator using Hanau SpringBow.

Comparative evaluation of hight tracer, Chandra tracer, intraoral tracer, functiograph and checkbite: A clinical study

PURPOSE: Centric and eccentric relations of mandible can be recorded through check bites, graphic recordings, functional recordings and cephalometrics. These records are then transferred to a semi-adjustable articulator so that it can be set to simulate the human system. This study is an attempt to compare the relative accuracy of the checkbite and graphic recordings using cephalometrics as a standard. AIMS: • To compare the efficiency of hight tracer, Chandra tracer, Conventional intraoral tracer, Functiograph and Checkbite in determining centric relation. • To compare the efficiency of hight tracer, Chandra tracer, Conventional intraoral tracer, Functiograph and Checkbite in determining horizontal condylar guidance angle on Hanau H2 articulator with the aid of both centric and eccentric records. • To compare the horizontal angle values thus obtained on the Hanau H2 articulator with horizontal angle values in cephalometric tracings. MATERIALS AND METHODS: Hight tracer, Chandra tracer, Conventional intraoral tracer, Functiograph and Checkbite were used on 10 edentulous subjects to obtain centric and protrusive records. Lateral cephalograms were made at both centric and protrusive positions with each method and the horizontal condylar values thus obtained were compared with those obtained on Hanau H2 articulator. RESULTS: • There was no statistical difference between the cephalometric and articulator values in all the five experimental methods. • There was no significant difference between Hight tracer, Chandra tracer, Intraoral tracer, Functiograph and Checkbite methods. • Ranking the experimental methods in the order of efficiency: the first was the Intraoral tracer, second being Functiograph followed by Chandra tracer, Checkbite and Hight tracer. • Checkbite alone can be used to set the horizontal angles on the articulator in edentulous subjects, clinically. • Tracings can be used as a verificatory method. • Centric relation position was found to be the same in a subject with all the experimental methods. • Each experimental method can influence the condylar path differently in the eccentric position. CONCLUSIONS: The articulator value of horizontal condylar angle was higher than cephalometric value in majority of the subjects in all the five experimental methods.

Wear in the upper and lower incisors in relation to incisal and condylar guidance.

The incisors of 85 patients were examined for tooth wear with the aim to evaluate possible association between the degree of wear and anterior guidance. Apart from clinical functional analysis electronic axiography using the system CADIAX was carried out. Anterior guidance in protrusive movement was marked on individually mounted plaster casts and scanned using a pantograph. The cephalometric analysis program CADIAS was used for the metric determination of the anterior guidance angle to the axis-orbital plane, and in order to relate the anterior guidance to the horizontal condylar inclination. The interincisal angle was included in the evaluation as a further functional angle and according to overjet and overbite there were classified typical incisor relations. Where both anterior guidance and incisor inclination and relation were in the normal range, there was an increase in incisal tooth wear in the group investigated. With reduced functional space, frequently found together with anterior deep bite, incisor wear was less extensive. While the occurrence of parafunction was shown not to be related to anterior guidance and incisor inclination and relation parafunctions were the decisive factor in the occurrence of severe incisor wear. Where anterior guidance and incisor inclination and relation are normal, the area of enamel under load is smaller and the space for bruxism larger. Parafunctional forces thus appear to result in a higher degree of wear than is found with the reduced functional space of a steep incisor position. Anterior guidance could not be evaluated as a parafunctonal inducing factor, but only as determining the wear pattern in the individual.

Investigation of the effects of a variable lateral guidance incline on the pantronic registration of mandibular border movement: Part II

This study was designed to test the hypothesis that changes in lateral guidance inclination could affect the condylar registrations in the recordings of an electronic pantograph. In seven healthy subjects, pantronic registrations of immediate side shift, progressive side shift, and orbiting and protrusive condylar paths were recorded with lateral anterior guidance inclinations of 0, 20, 30, 45, and 60 degrees from the same pin height. Analysis of variance with repeated measures showed a significant decrease in the immediate side shift ( p 0.016) and the progressive side shift ( p 0.051) as the lateral guidance angle increased and no significant effect on the orbiting registrations. These observations, together with those from other studies, suggest that the concept of fabricating the working-side tooth guidance exactly according to instrument condylar settings (which themselves may be subject to a variable recording lateral anterior guidance) appears untenable and demands further study.

Temporomandibular joint vibration analysis in a sample of non-patients.

In a sample of 20 non-patients, 60% of the subjects had an absence of subjective temporomandibular joint (TMJ) complaints (noises/sounds) that agreed with objective joint vibration analyses (electrovibratography). Among the remaining 40% of subjects, only 50% of the examined joints showed agreement between subjective and objective findings. Subjects appeared to be unable to reliably detect "weak" (early) symptoms of TMJ dysfunction but were able to reliably detect "strong" (late) symptoms of TMJ dysfunction and possibly disease. As measured through active protrusion and laterotrusion of the mandible, the guidance angles of the anterior teeth could not explain the absence and presence of TMJ vibrations.

The concept of the sagittal condylar guidance: biological fact or fallacy?

The clinical concept of a sagittal condylar guidance pertaining to the human temporomandibular joint is discussed in the light of selected studies on the anatomy, radiography and cineradiography of this joint, and clinical attempts at recording a sagittal condylar guidance. It seems as if there is no single and well defined sagittal condylar guidance in vivo, and thus no single and well defined sagittal condylar guidance angle applicable to the adjustable articulator.

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.