Protrusive Interocclusal Record Research Articles

Comparison of Sagittal Condylar Guidance Angle Obtained by Radiographic Methods and Manual Programming of Articulators in Dentate Patients – A Clinico-radiographic Study

Background: The ultimate goal of advanced procedures in prosthetic dentistry is to construct a prosthesis based on the accurate reproduction of condylar guidance. Aim: To compare the sagittal condylar inclination obtained using the cone-beam computed tomography (CBCT), panoramic image, and two articulator systems. Settings and Design: A cross-sectional study was carried out in 20 dentate patients in the age group of 20–40 years. Materials and Methods: Sagittal condylar guidance angles (SCGAs) were measured on two semi-adjustable articulators (Hanau Wide Vue and Denar Mark 320) using protrusive interocclusal record. SCGAs were also measured on the CBCT scans (CBCT reconstructed panoramic image and CBCT sagittal cross section) and the panoramic images obtained from the patients. The angles were determined on the radiographs by joining two lines: Frankfort’s horizontal plane and the other plane were drawn by connecting the superior-most point on the glenoid fossa and the inferior-most point on the articular eminence. All the measurements were done twice by two operators independently. Statistical Analysis Used: The data were analyzed using the paired t-test and Pearson’s correlation coefficient with a P ≤ 0.05. Results: There was no significant difference between the right and the left side in any of the groups (P ≥ 0.05). In addition, there was no significant difference between the clinical methods (P ≥ 0.05). However, there was a significant difference between the clinical and the radiographic methods (P ≤ 0.05). Furthermore, there was a strong correlation between the clinical and radiographic methods with Pearson’s Correlation coefficient above 0.67. Conclusion: There is a strong correlation between the clinical and radiographic methods. Thus, CBCT and OPG can be used an adjunct to clinical methods to record sagittal condylar guidance.

A systematic review and meta-analysis of accuracy between protrusive interocclusal record and horizontal condylar guidance angle recording methods in dentulous patients.

This systematic review and meta-analysis aimed to evaluate the accuracy of different methods used for measuring horizontal condylar guidance (HCG) angle in comparison with protrusive interocclusal record (IOR) for dentulous patients. The design involves systematic review and meta-analysis following the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. An electronic search was carried out by two reviewers in the Google Scholar search engine and the EBSCO host, Cochrane Library, and PubMed/MEDLINE databases for quasi-experimental studies, in vivo studies, and cross-sectional studies published from January 2005 to February 2023 determining the HCG angle in dentulous patients. Meta-analysis was performed to evaluate the quantitative data. A total of 577 articles were identified, 29 analytical cross-sectional studies that fulfilled the eligibility criteria were included for qualitative synthesis and 26 studies were included for meta-analysis. A statistically significant difference was observed for the right and left HCG angles obtained by the panoramic radiograph method and cone-beam computed tomography (CBCT) method and for the right side HCG angle obtained by cephalogram method showing higher values than the protrusive IOR method. No statistically significant difference was observed for the left side HCG angle obtained by the cephalogram method and both the right and left side HCG angles obtained by the intraoral tracer method. The panoramic radiograph, cephalogram, and CBCT obtained higher HCG angles in dentulous patients than the protrusive IOR method.

A comparative evaluation of sagittal condylar guidance obtained by the protrusive interocclusal record and panoramic radiographic tracing in both dentulous and edentulous patients

A comparative evaluation of sagittal condylar guidance obtained by the protrusive interocclusal record and panoramic radiographic tracing in both dentulous and edentulous patients

Comparative Evaluation Of Clinical And Radiographic Horizontal Condylar Guidance Angle Values By Using Two Different Interocclusal Recording Materials In Dentulous Patients

Introduction: The success of prosthodontic procedures can be accurately determined by the exact replication of the patient’s condylar path using a semi-adjustable articulator. It allows the clinician to determine the morphology of the occlusal surfaces in relation to the condylar pathway during mandibular movements. If condylar guidance is not exactly registered, it might result in occlusal interferences during movements of the mandible and lengthen chairside adjustment time, which is inconvenient for the patient and dentist.Materials and methods: A total of 20 dentulous patients from 20 to 30 years of age group attending the department of prosthodontics at Sibar institute of dental sciences were selected for the study. Alu wax and jet bite were used to obtain the protrusive interocclusal record (PIR). Protrusive records were then used to program the semi-adjustable articulator to obtain HCGA values on both sides. Using the same protrusive records CBCT radiograph was taken. Radiographic images were traced on tracing paper and HCGA values were measured using Frankfort’s horizontal reference line (the line connecting porion and orbitale) and the mean curvature line (most-superior and most-inferior points of the curvatures) on both sides using a protractor. The data were analyzed by paired sample t-tests and Pearson’s correlation tests.Results: There was no significant difference between the right and left sides in the clinical and radiographic methods using Alu wax PIR. In the clinical method utilizing jet bite PIR, the right side had significantly higher HCGA values than on the left side. On CBCT, no such differences were found.Conclusion: CBCT horizontal condylar guidance angle values were higher than those obtained using the clinical method by using both records. Values obtained from both the methods, i.e., protrusive interocclusal record and cone-beam computed tomography, were compared and correlated.

Evaluation of Sagittal Inclination of Occlusal Plane and Horizontal Condylar Guidance Using Various Anterior Reference Points on Arcon and Nonarcon Articulators.

Aim:The aim of the study was to determine the effect of different anterior reference points during facebow transfer, on sagittal inclination of occlusal plane (SIOP) and horizontal condylar guidance (HCG) values obtained on arcon and nonarcon articulators.Materials and Methods:Facebow records of 25 participants were made and transferred to Hanau Wide-Vue (WV) and Hanau H2 (H2) articulators using conventional indirect transfer (CIT), superior annular groove (SAG), and inferior annular groove (IAG) as anterior reference points. Maxillary casts were mounted on each articulator followed by mandibular mountings. Protrusive interocclusal record was used to determine HCG, and SIOP was measured as an angle between the occlusal plane of mounted maxillary cast and upper member of the articulator. Both, HCG and SIOP were measured on a digital lateral cephalogram and the values obtained were compared with previously determined values from both the articulators. Intergroup comparison was done by analysis of variance and pair-wise comparison by Tukey post hoc test.Results:Values of SIOP significantly (P = 0.00) changed on both the articulators when CIT, SAG, and IAG were the anterior reference points. The ratio of SIOP and HCG on both articulators was comparable to that of the cephalogram for CIT, IAG, but it was substantially low for SAG.Conclusions:The variation of anterior reference point changes the value of SIOP recorded on Hanau WV and H2 articulators; however, it had no effect on HCG values recorded on both the articulators. The angle between SIOP and HCG changed with variations in superior-inferior position of the mountings on both articulators.

Comparison Of Sagittal Condylar Angle Obtained Using Cone Beam Computed Tomography And Interocclusal Record Materials- An In Vivo Study

: The sagittal condylar guidance angle (SCCA) is calculated by the condyle and articular disc traversing the contour of the glenoid fossa and the articular eminence. The condylar path is controlled by the shape of the fossa, the attachments of the ligaments, the biting load during movement (muscular influence), and the amount of protrusion. The SCGA on an articulator is determined using protrusive records of the patient. Intraoral registrations may compromise accuracy because of dimensional instability of registration materials and it becomes difficult for the dentist to select an appropriate material. The use of cone beam computed tomography (CBCT) has recently become much more common, and when measuring the SCGA using CBCT, more reliable results can be expected. This study was designed to compare the SCGA obtained using CBCT and protrusive interocclusal record made using polyvinyl siloxane and aluwax. Thirty dentulous subjects were selected. SCGA was calculated using CBCT scans for each subject. Intraoral protrusive records were made using polyvinyl siloxane and aluwax bite registration materials at 6mm of protrusion. Records were used to program the articulator and variation in the SCCA was noted. No significant difference was observed between right and left mean values of SCGA in CBCT, polyvinyl siloxane and aluwax. Positive correlation was found between all the three groups; however, significant difference was found in the mean values of SCGA between CBCT and polyvinyl siloxane, CBCT and aluwax (P=0.0001). No significant difference was found in the mean values of SCGA between polyvinyl siloxane and aluwax (P=0.9254). CBCT gave higher mean SCGA values than those obtained using polyvinyl siloxane and aluwax on semi-adjustable articulator in dentulous subjects; whereas mean SCGA values were comparable between polyvinyl siloxane and aluwax. The right and left SCGA values were comparable in each method.

English

BACKGROUND One of the most widely used methods to record horizontal condylar guidance is the use of protrusive interocclusal records. Therefore, this study was done to evaluate the reliability of protrusive interocclusal record with and without the influence of anterior determinant on horizontal condylar guidance among dentulous patients. METHODS Diagnostic impressions of 21 participants were made and casts were poured. Facebow record were obtained and transferred to semi-adjustable articulator. Protrusive interocclusal records were made using Alu-wax. In group 1, protrusive interocclusal records were obtained at incisal edge to edge position (conventional method). In group 2, 3 and 4 protrusive interocclusal records were obtained at a distance of 4 mm, 6 mm and at incisal edge to edge position respectively using a customized flat anterior jig. Programming of the Hanau articulator were done for all the 4 groups. One-way ANOVA test and Pearson’s correlation tests were done to compare and correlate horizontal condylar guidance. RESULTS The mean values obtained for flat anterior jig at incisal edge to edge position, at 4 mm and 6 mm provided good Pearson correlation values for the right (R = 0.773, R = 0.779, R = 0.632) as well as the left side (R = 0.631, R = 0.601, R = 0.545) respectively, on comparison with the conventional incisal edge to edge values. This indicated a positive correlation which was statistically significant. CONCLUSIONS The horizontal condylar guidance is influenced by anterior determinant. Therefore, the reliability of protrusive records is dependent on eliminating the influence of anterior determinant. KEY WORDS Horizontal Condylar Guidance, Anterior Determinant, Protrusive Interocclusal Records

A Novel Technique to Align the Intraoral Scans to the Virtual Articulator and Set the Patient-Specific Sagittal Condylar Inclination.

Customized cast orientations and parameter settings of the virtual articulator according to the patient's condyles are indispensable parts of today's digital workflows in prosthodontics. This article describes a digital technique to align the intraoral scans to a virtual articulator by using a facial scanner to locate the patient's cutaneous landmarks of the arbitrary hinge axis and the reference plane, and to customize the sagittal condylar inclination of the virtual articulator through a digital protrusive interocclusal record and a dental computer-aided design software program. It enables individual cast orientations and virtual articulator parameter settings without conventional facebow transferring and bite registration procedures and can be easily integrated with most virtual articulator systems on the market to allow clinicians and technicians to work in a complete digital workflow and facilitate customized treatment planning and dental prosthesis fabrication.

Reproducibility of Sagittal Condylar Path Inclination Assessed by Protrusive Interocclusal Record with Two Different Techniques of Facebow Registration

Purpose: The purpose is to validate whether the data obtained for sagittal condylar inclination are correctly reproduced on the semi-adjustable articulator using protrusive interocclusal records for conventional facebow registration method (orbitale (OR) as an anterior point of reference) and facebow registration using bubble leveler (BL) as an anterior point of reference and compared these values with the values obtained by lateral cephalogram (gold standard). Materials and Methods: In total, 30 individuals (20 males and 10 females) with proper teeth alignment, facebow registrations were recorded using OR as an anterior point of reference (Group A, conventional technique) and WBL as an anterior point of reference (Group B). The sagittal condylar path inclination was measured and compared using protrusive interocclusal records for both the groups. These values compared with the values for sagittal condylar path inclination obtained using lateral cephalogram (Group C) using one-way analysis of variance (P < 0.05). Results: There was no statistically significant differences observed in the values of sagittal condylar inclination for all three groups with P = 0.583. Conclusion: This study suggests that BL technique can be used for the orientation of maxillary cast on the semi-adjustable articulator as accurately as the conventional approach, for those practitioners who find difficulty in locating the OR for those patients with deformity in facial region. Lateral cephalogram provides almost the same measurements of sagittal condylar path inclination as obtained using protrusive interocclusal record on facebow registrations using OR and BL as an anterior point of references.

Comparative evaluation of sagittal condylar guidance obtained from a clinical method and with cone beam computed tomography in dentate individuals

Statement of problemProgramming semiadjustable and fully adjustable articulators involves time-consuming clinical steps which can be avoided if an accurate radiographic method can accurately determine the condylar guidance angles. PurposeThe purpose of this clinical study was to compare the sagittal condylar guidance in dentate individuals as determined by a clinical method, protrusive interocclusal record, and a radiographic method, cone beam computed tomography. If the methods show a correlation, then cone beam computed tomography can be used as a time-saving method of programming an articulator for patients requiring a cone beam computed tomography scan. Material and methodsA total of 40 participants (20 men and 20 women) within the 20 to 40 years age group were enrolled according to the inclusion and exclusion criteria. Cone beam computed tomography scans were obtained, and by using an appropriate software program, the sagittal condylar guidance was measured for both sides. A protrusive interocclusal record was obtained by using polyvinyl siloxane material. The maxillary cast of each participant was mounted on a semiadjustable articulator with a facebow transfer, and the mandibular cast was mounted with a maximum intercuspal record. The protrusive record was then transferred to the articulator for programming. ResultsThe right and left sagittal condylar guidance values obtained from both the protrusive interocclusal record and cone beam computed tomography method were comparable, with no significant differences (P>.05). The difference in condylar inclination values for both sexes obtained from both methods for both sides were not statistically different (P>.05). With increasing age, condylar inclination values obtained from both methods tended to decrease. The values for sagittal condylar guidance obtained from both methods (protrusive interocclusal record and cone beam computed tomography) were comparable and correlated. ConclusionsCone beam computed tomography measurement involves stable bony landmarks and can be standardized, whereas clinical methods are time consuming and can provide inaccurate results because of the instability of the materials used to register the maxillomandibular relationship. Thus, cone beam computed tomography can be used to obtain the sagittal horizontal guidance for programming semiadjustable and fully adjustable articulators for patients requiring a cone beam computed tomography scan.

A Comparative study to measure the horizontal condylar guidance obtained by protrusive interocclusal records and panoramic radiographic images in completely edentulous patients

Background & Objectives:The study was conducted with objective to compare the horizontal condylar guidance (HCG) obtained by protrusive interocclusal records and panoramic radiographic images in completely edentulous patients.Materials & Methods:The horizontal condylar guidance was measured in 25 completely edentulous patients by protrusive interocclusal records using zinc oxide eugenol paste through a face bow transfer (HanauTM Spring bow, Whip Mix Corporation, USA) to a semi-adjustable articulator (HanauTM Wide-Vue Articulator, Whip Mix Corporation, USA). In the same patients, HCG was traced in the panoramic radiograph. The angles formed by the intersection of two lines: Frankfurt’s horizontal plane and posterior slope of articular eminence was measured using protractor to represent the horizontal condylar guidance angle on each side.Results:The mean difference between the horizontal condylar guidance angles values obtained using protrusive interocclusal record and panoramic radiograph was 2.68 degrees and 3.40 degrees for the right and the left side respectively, with the panoramic radiograph values being higher. This difference between the values was found to be highly significant between the two methods for the right side (t = 2.70, p = 0.012) and left side (t = 3.69, p = 0.001). A significant positive correlation was found between the horizontal condylar guidance obtained from protrusive interocclusal record and panoramic radiograph for the right (r = 0.643, p = 0.001) and left sides (r = 0.622, p = 0.001) separately.Conclusion:The panoramic radiographic tracing can be used to calculate the mean horizontal condylar guidance in the completely edentulous patients and these values can be used to programme semi-adjustable articulators avoiding the cumbersome process of obtaining protrusive interocclusal records.

A clinico-radiographic study to compare and co-relate sagittal condylar guidance determined by intraoral gothic arch tracing method and panoramic radiograph in completely edentulous patients.

Purpose:The purpose of this study was to compare and correlate sagittal condylar guidance determined by intraoral gothic arch tracing method and panoramic radiograph in edentulous patients.Materials and Methods:Twelve completely edentulous patients were selected by the inclusion and exclusion criteria. Conventional steps in the fabrication of complete denture till jaw relation were carried out. Intraoral gothic arch tracing and protrusive interocclusal records were obtained for each patient. Protrusive interocclusal record was used to program the Hanau Wide-Vue semi-adjustable articulator, thus obtaining the sagittal condylar guidance angle. Using RadiAnt DICOM software, on the orthopantomogram obtained for each patient in the study, two reference lines were drawn. The Frankfort's horizontal plane and the mean curvature line (joining the most superior and the inferior points on the glenoid fossa curvature) were drawn. The mean curvature line was extended to intersect the Frankfort's horizontal plane, thus obtaining the radiographic sagittal condylar guidance angle. The condylar guidance angles obtained by these two methods were compared and subjected to paired t-test.Results:There was no statistically significant difference between the sagittal condylar guidance angles obtained between right and left sides with intraoral gothic arch tracing and radiographic methods (P = 0.107 and 0.07, respectively).Conclusion:Within the limitations of this study, it was concluded that the protrusive condylar guidance angles obtained by panoramic radiograph may be used for programming semi-adjustable articulators.

Correlation between sagittal condylar guidance angles obtained using radiographic and protrusive occlusal record methods.

PURPOSEThis study compared the SCGAs measured in three types of radiographic images (panoramic, CBCT panoramic-section, and CBCT cross-section images) with values measured using the protrusive occlusal record.MATERIALS AND METHODSSCGAs were measured in 20 patients on a semi-adjustable articulator using the protrusive interocclusal record. Panoramic and CBCT images were obtained. SCGAs were measured on CBCT images in panoramic and cross sections. In all of the radiographic images, SCGAs were measured using the Frankfort horizontal reference line and the mean curvature line. The most-superior and most-inferior points of the curvatures were identified to determine the mean curvature line. Each measurement was performed twice by two operators independently. The data were analyzed by the t-test, Pearson's correlation test, and Cronbach's α using SPSS (α=.05).RESULTSThe mean right and left SCGAs were as follows: protrusive occlusal record (30.1 and 30.2 degrees, respectively), panoramic (38.9 and 38.7 degrees), CBCT panoramic sections (35.4 and 36.8 degrees), and CBCT cross sections (35.3 and 36.1 degrees). The SCGAs differed significantly among the groups. The Pearson coefficients for the correlations with the protrusive occlusal record measurements on the left and right sides were as follows: panoramic (0.834 and 0.791, respectively), CBCT panoramic-section (0.918 and 0.837), and CBCT cross-section (0.918 and 0.845) images.CONCLUSIONStrong correlations were found between SCGAs obtained using radiographic images and the protrusive occlusal record.

Evaluation of condylar inclination of dentulous subjects determined by axiograph and to compare with manual programming of articulators using protrusive interocclusal record.

Aims:To determine the average condylar inclination using ultrasonic axiograph; to determine the average condylar inclination using protrusive interocclusal bite records; to compare whether there is any marked difference in the values obtained by these techniques.Settings and Design:This clinical study compares the mean horizontal condylar inclination of the ultrasonic axiograph (Axioquick system) and the manual programming using protrusive interocclusal records.Materials and Methods:The study was conducted on a group of 30 subjects reporting to Department of Prosthodontics. Axioquick software system of SAM III (School Articulator Munich) fully-adjustable articulator was used, and interocclusal recording of condylar inclination is the manual method used in semi-adjustable articulators using Aluwax. The condylar inclination of the articulator was adjusted and set using protrusive interocclusal record.Statistical Analysis:The horizontal condylar inclination values of both methods were collected, and the mean of right and left condylar inclination was compared using paired t-test.Results:A statistically significant difference exists between Axioquick system and the manual method of programming articulator with protrusive interocclusal records (P ≤ 0.001).Conclusions:Within the limitations of the present study, the following conclusions were drawn: The average condylar inclination by axiograph is 42.125°. The average condylar inclination by interocclusal record is 33.25°. Comparison of both values shows a difference of 8.88° ± 4.03° that showed a significant difference (P < 0.001).

A clinical study of the variation in horizontal condylar guidance obtained by using three anterior points of reference and two different articulator systems

Background and Objectives:For mounting the maxillary cast to articulator, minimum three reference points not on single line, decide the plane to which maxillary cast is mounted. Variations exist in condylar guidance when different anterior reference points are used to mount the cast. Type of articulator may have influence on condylar guidance. A clinical study was planned to evaluate the effects of different anterior points of reference and two different articulator systems on condylar guidance.Materials and Methods:Total 15 subjects were selected. Six sets of maxillary casts were obtained. Face bow record was made using orbitale as anterior point of reference and the record was transferred to the Arcon and Non-Arcon articulator. The second and third mounting on Arcon and Non-Arcon articulator were done using Superior and inferior annular groove on incisal pin of articulator. Protrusive interocclusal records were made for all the subjects. Two lateral cephalograms one in maximum intercuspation and the other in protrusion for left and right side were taken. Anatomic condylar guidance of the subject were obtained from radiograph tracing. Arcon and Non-arcon articulator were programmed with Protrusive interocclusal record of the subjects and the condylar guidance was tabulated for right and left side. The procedure was repeated for all three mountings for both the articulators.Results:The orbitale is the best reference point which mounts maxillary cast closer to anatomic position. Inferior annular groove can also be used as anterior point of the reference. The superior annular groove is not recommended anterior point of reference.

Age Changes in Horizontal Condylar Angle: A Clinical and Cephalometric Study

Determination of condylar inclination is important when restoring the occlusal surfaces of teeth. It is important to know the changing trends in horizontal condylar inclination with age so as to have an idea about the cuspal morphology. a) to determine the effect of age changes in horizontal condylar inclination using articulator method and radiographic method (cephalometry) b) to compare the values of horizontal condylar inclination obtained using articulator method with that of cephalometric method c) to ascertain the symmetry of horizontal condylar angle on both right and left side on an articulator. 40 dentulous individuals with Angle's class I occlusion were selected for the study. They were divided into four groups Group I: 20-29years, Group II: 30-39years, Group III: 40-49years, Group IV: 50-59years. Horizontal condylar inclination was determined on right and left side for each individual using protrusive interocclusal record in a Dentatus (ARL) semiadjustable articulator. Cephalometric recording was carried out twice on the left side, once in centric occlusion position and then in protrusive position. The two radiographs were superimposed to draw a line connecting the shifting position of condylion on an acetate tracing paper. This line when joined with Frankfurt horizontal plane gives the horizontal condylar inclination. Analysis of variance (ANOVA) revealed that there was a significant difference in horizontal condylar angle values in all the four groups which were statistically significant. There is a decrease in horizontal condylar angle values from Group I to Group IV. Horizontal condylar values obtained by articulator method and cephalometric method showed no significant difference for all the four groups tested. When horizontal condylar values obtained on right and left sides of Dentatus articulator were compared there was not much of a significant difference. Horizontal condylar values showed a decreasing trend with increasing age, i.e, as age advances there is a flattening of condylar head. Both articulator and cephalometric method yielded no significantly different values and hence both the methods can be used for determining condylar inclination. The difference in values of horizontal condylar angle on right and left sides were insignificant.

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.

Comparative evaluation of the curve of Spee in two age groups and its relation to posterior teeth disclusion

This study aims to compare the curve of Spee in human permanent healthy dentitions in two age groups to the disclusion in the premolar and molar region during protrusion. Sixty subjects were chosen and equally divided into two age groups of 18-25 years and 35-44 years. The left side of the mandibular dental casts was photographed using a digital camera to measure the curve of Spee. The canine cusp, mesiobuccal cusp of the first molar and the distal cusp of the second molar were marked and joined to form an arc. Using AUTOCAD software, the radius for this arc was obtained. A protrusive interocclusal record was made using rigid bite registration material to measure the amount of posterior disclusion during edge to edge protrusion. A dial gauge with an accuracy of 1/100 of a millimeter was used to measure the distance between the cusp tip indentations at the region of the buccal cusp of the mandibular 2nd premolar and distobuccal cusp of mandibular 1st molar. The results obtained were statistically analyzed. The radius of curve of Spee increased nonsignificantly with age. The mean disclusion values measured in premolar and molar region showed a nonsignificant decrease with age. As age advances, there is a flattening of the curve of Spee and a concurrent reduction in the disclusion values during protrusion.

顎関節症状自覚者のこう合接触状態について

This study was conducted to make clear the extraordinary occlusal contact. The subjects were 16 persons with nomal occlusion and 15 persons with a subjective symptom of TMJ dysfunction. These subjects were recorded intercuspal position and lateral and protrusive interocclusal record by silicone impression materials. They were measured electromyography.1. For subjects with nomal occlusion, the contact teeth number of intercuspal position was at least 18-teeth, At lateral position these 16 persons had a tendency that canine on working side there was contact and on nonworking side no contact. When the molar on working side had the contacts, the molar on nonworking side had the contacts. At protrusive position they had bilateral incisal contacts.2. For subjects with symptom of TMJ dysfunction, there were 3 persons that the contact teeth at intercuspal position were less than 11. At lateral position, these 15 persons had more patterns of occlusal contact than 16 subjects with nomal occlusion. And the different patterns were 11 varieties. At protrusive position, these subjects had more patterns of occlusal contact than 16 subjects.3. In some cases there were relations among the symptons of TMJ dysfunction and the occlusal contact and electromyography.