Horizontal Condylar Inclination Research Articles

A comparative assessment of condylar inclination in completely edentulous patients using cone beam computed tomography and Arcus digma II

Statement of problemCondylar inclination affects denture fabrication and placement, especially when bilateral balanced occlusion is provided. However, comparisons between radiographic techniques and clinical procedures are lacking. PurposeThe purpose of this clinical study was to investigate the effects of cone beam computed tomography (CBCT) and Arcus digma II on horizontal condylar inclination and bilateral balanced occlusion. Material and methodsTwelve completely edentulous individuals were provided with complete dentures with teeth in bilateral balanced occlusion. The horizontal condylar angle was measured using CBCT and the Arcus digma II with a 6-mm mandibular protrusion. The CBCT had a real-time 3D image, and the Arcus digma II method recorded mandibular movement using electronic sensors. To evaluate the clinical performance, the horizontal condylar angle was measured using the 2 methods and applied to the semi-adjustable articulator to evaluate the balanced occlusion. The Shapiro-Wilk test was used to assess normality, and a paired t test was used to assess the normally distributed data (α=.05). ResultsThe horizontal condylar guidance angle values for both sides of Arcus digma II were significantly higher than from CBCT (P<.05). No difference was found in the clinical performance of balanced occlusion of complete dentures in the 2 methods. ConclusionsThe Arcus digma II method yielded higher horizontal condylar angle measurements than from CBCT. However, no significant difference was found between Arcus digma II and CBCT in terms of the effect on balanced occlusion. Arcus digma II appears to be a reliable technique for measuring the horizontal condylar angle, similar to CBCT, and can be used as an alternative method.

Analysis of Mandibular Movement after insertion of Fixed Partial Dentures using Cadiax Compact II®

The aim of this clinical study was to analysis the mandibular movement in patients after insertion of fixed partial dentures using Cadiax Compact II and compares the Horizontal condylar angles and Bennette angles before and after insertion of posterior fixed partial denture.Material and methods: Mandibular movement of thirty two patients, sixteen males and sixteen female planed for posterior fixed partial dentures), had been recorded using Cadiax Compact II® for Horizontal Condylar Inclination and Bennette Angle. Three records had been obtained R1 before the abutments teeth preparations of the Fixed Partial Dentures, R2 after the cementation of the Fixed Partial Dentures and R3 after one month of the Fixed Partial Dentures cementation.Results: Statistical highly significant difference was found between R1&amp;R2 for Bennette angles in both males and females, and significant difference in group R1&amp;R3 for Horizontal condylar Inclination in females only. The other groups show no statistical significant difference.Conclusion: Within the limit of this clinical study, the insertion of fixed partial denture have no changing effect on the Horizontal Condylar inclination in males but in females have mild change. For Bennette angle there is highly significant change in both males and females immediately after the fixed partial denture cementation, but after one month this change disappeared.

The prevalence of temporomandibular disorder and temporomandibular morphology among diverse chronotype profiles

ABSTRACT This study investigates the influence of chronotype on the prevalence of temporomandibular joint disorders (TMD) and the morphology of temporomandibular joint (TMJ). According to the Morningness–Eveningness Questionnaire-Self-Assessment, the participants were divided into morning group (n = 30), intermediate group (n = 83), and evening group (n = 30). Thirty participants were randomly selected from the intermediate group for subsequent examination and measurements. The morphology of TMJs was investigated using questionnaire and clinical examination form in Diagnostic Criteria for Temporomandibular Disorder. Meanwhile, the morphological results of TMJs were measured from cone-beam computed tomography images. The prevalence rate of TMD in the morning group (23%) was significantly lower than that in the intermediate group (56.7%), while there was no difference between the evening (53.4%) and intermediate groups. As to morphological measurements, there was no significant difference among three groups in mediolateral width of condylar process, anteroposterior width of condylar process, radius of condyle, medial joint space, lateral joint space, condylar stress angle, horizontal condylar inclination, width of glenoid fossa, depth of glenoid fossa, and posterior joint space, while there was a significant difference in horizontal condylar angle (p = 0.00490), articular eminence inclination (p < .0001), anterior joint space (p = 0.0163), and superior joint space (p = 0.0004). The morphology of TMJ in the morning group was better than that in the evening and intermediate groups. An association was found between TMD prevalence, temporomandibular morphology, and chronotype.

Inclination of the osseous components of the temporomandibular joint related with disc displacement: Magnetic resonance and cone beam computed tomography imaging-based study

ABSTRACT Objective To assess the association between three-dimensional inclination of the osseous structures of temporomandibular joints (TMJ) and the risk of disc displacement (DD). Methods The 120 TMJs of 60 patients were evaluated. According to magnetic resonance images, disc position was classified as normal, anterior DD with reduction (ADDWR) and without reduction (ADDWoR) and as normal, medial DD (MDD), and lateral DD (LDD) on the sagittal and coronal views, respectively. Condyle and eminence inclinations were measured using cone beam computed tomography. Results Smaller horizontal condylar inclination was associated with ADDWoR (p < 0.05). Larger coronal condylar inclination was associated with ADDWR (p < 0.05) and LDD (p < 0.05). There was no association between sagittal eminence inclination and DD (p < 0.05). Conclusion Medial condylar rotation in the axial view may be associated with ADDWoR. The condyle head horizontally inclined in the coronal view may be associated with ADDWR and LDD.

Comparative evaluation of condylar guidance obtained by three different interocclusal recording materials in a semi-adjustable articulator and digital panoramic radiographic images in dentate patients: An in vivo study.

Aim:The Aim of the study was to evaluate the reproducibility of condylar inclination values obtained using three different interocclusal recording materials in Hanau Wide-Vue semi-adjustable articulator and to compare those values of condylar inclination with panoramic radiographic images.Settings and Design:In Vivo Comparative study.Materials and Methods:The clinical trial was carried out in the Department of Prosthodontics, M. R Ambedkar Dental College and Hospital, Bengaluru. A total of 30 dentulous subjects aged between 20 and 40 years were selected, without any signs and symptoms of temporomandibular joint disorders. With the help of a custom-made protrusive guide, protrusive records for three materials were made. These records were used for programming the articulator and the respective horizontal condylar inclination (HCI) value, and panoramic radiographs were made. The values obtained were statistically analyzed.Statistical Analysis Used:Independent t-test, multiple comparisons using Bonferroni method followed by Analysis of variances (ANOVA) were used.Results:Among each pair of groups there exists a significant difference, i.e., the mean condylar inclination (degree) was found to be statistically significant between wax and polyvinyl siloxane (P < 0.01) as well as between wax and polyether (P < 0.01). No significant difference was observed between polyvinyl siloxane and polyether (P > 0.05).Conclusion:HCI values differed depending on the type of material employed. The study concluded that the protrusive condylar guidance angles obtained by panoramic radiograph can be used in programming the semi-adjustable articulator and among the materials polyether gave the highest Condylar Guidance values with less variability and wax gave lowest values with greater variation.

Impact of mounting methods in computerized axiography on assessment of condylar inclination

Objective: Valid and reliable recording is a key requirement for accurately simulating individual jaw movements.Methods: Horizontal condylar inclination (HCI) and Bennett’s angle were measured using a digital jaw tracker (Cadiax® Compact 2) in 27 young adults. Three mounting methods (paraocclusal tray adapter, periocclusal tray adapter, and tray adapter with mandibular clamp) were tested.Results: The mean values of the HCI differed by up to 10° between the mounting methods; however, the values for Bennett’s angle did not differ substantially. While the intersession reliability of the Bennett’s angle assessment did not depend on the mounting method, the reliability of the HCI assessment was only fair to good for the paraocclusal mounting method but poor for both periocclusal mounting methods.Discussion: For attaching the tracing bow of jaw trackers to the mandible, a paraocclusal tray adapter should be applied, to achieve the most reliable results.

Ascertaining of temporomandibular disorders (TMD) with clinical and instrumental methods in the group of young adults

Introduction. During the diagnostic process, the clinical examination of the masticatory system combined with jaw movement measurements can indicate the presence of temporomandibular disorders (TMD) symptoms. Aim. The aim of the present study was to determine the presence of clinical symptoms of TMD in a group of subjects aged 19–27 years and to analyze the measurable parameters obtained from examinations carried out using the Arcus®digma.Material and methods. Eighty four dentate subjects from 19 to 27 years were recruited from students. Objective signs were studied with Helkimo Anamnetic index (Ai) and the subjective symptoms were evaluated with Gsellmann’s Occlusal Index (OI). Functional examination of the masticatory system was performed using Helkimo Clinical Dysfunction index (Di). Pain symptoms were determined in clinical examination using visual analogue scale. Software of Arcus®digma allowed the analysis of Bennett’s angle and movement, the horizontal condylar inclination, retrusion, anterior guidance and Immediate Side Shift.Results. Occasional pain occurred in 39% of students and correlated with increase of OI index, subjects with higher Di displayed higher values of OI. Comparison of Bennett’s angle values for the right and left TMJ showed the significant asymmetry, similarly like the values of Bennett’s movement and retrusion between the left and right TMJ.Conclusions. Bennett’s angle, Bennett’s movement and retrusion were significant parameters in instrumental evaluation of TMD symptoms. The questionnaire and clinical examination supplemented with axiographic recordings revealed the presence of TMD symptoms in students who were not fully aware of TMJ disorders.

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 newer technique to program a semi adjustable articulator.

Introduction:The difficulty in reproducing accurate angle of condylar guidance in semi-adjustable articulators.Purpose:The purpose of this study was to determine the correlation between the angle of horizontal condylar inclination obtained on a semi-adjustable articulator and the corresponding angle traced on a temporomandibular joint (TMJ) radiograph in completely edentulous subject.Materials and Methods:The horizontal condylar inclination angle was obtained in a semi-adjustable articulator by means of height tracer (extra oral tracing device) and interocclusal records to program the articulator in 21 subjects. TMJ radiograph were recorded by the same operator with same orthopantomogram (OPG) machine (planmeca). Tracings of inclines of articular eminence on the radiograph were compared with the angle obtained on a semi-adjustable articulator. Each measurement was made using manual methods of measuring angle. The results were subjected to the Pearson correlation statistical analysis (α =0.01).Results:The outline of the articular eminence in a TMJ tomogram radiographic image was identified and traced. A significant correlation was found between the horizontal condylar inclination on a semi-adjustable and the corresponding TMJ tomogram radiographic image for both right (R = 0.789; P = 0.001) and left (i = 0.747; P = 0.004) sides.Conclusion:The articular eminence traced on a TMJ tomogram image represents the horizontal condylar inclination with a mean difference of 5° in 21 subjects evaluated.

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.

Evaluation of the Cadiax Compact® II Accuracy in Recording Preadjusted Condylar Inclinations on Fully Adjustable Articulator

Mandibular movement analysis is a critical step in making the functional occlusal morphology and improving the diagnosis and treatment of temporomandibular joint disorders (TMDs). Cadiax Compact® is an electronic condylograph that claims to record the horizontal condylar inclination (HCI), Bennett angle (BA) and relative shape of the articular eminence. This study aims at assessing the accuracy of Cadiax Compact® II in its claimed abilities. The electronic condylograph (Cadiax Compact®II) was fitted on the fully adjustable articulator (gamma dental reference-SL). After setting of HCI and BA on the arbitrary degrees, eccentric movements were produced manually on the articulator. The Cadiax recorded these preadjusted angles and the accuracy of its recordings was assessed by comparison of the results with the preadjusted HCI, BA and color inserts as references. The majority of the comparisons showed statistically significant differences between articulator settings and Cadiax recordings. However, the maximum difference was about 2.50 which seems acceptable for clinical practice. The obtained results showed that Cadiax Compact is an accurate and reliable instrument for diagnostic purposes, yielding reproducible measurements. Despite this, Cadiax is a technically sensitive device that can preclude its routine usage.

Comparative Study of the Effect of Three Different Interocclusal Recording Materials on Reproducibility of Horizontal Condylar Registrations in Two Different Semiadjustable Articulators: A Clinical Study

ABSTRACT Purpose Simulation of jaw movements in an articulator requires one of the important condylar parameters, i.e. horizontal condylar inclination (HCI) to be registered in the patient and transferred to a mechanical device (articulator). The most popular and commonly used technique to determine horizontal condylar inclination (HCI) is by use of interocclusal records. Clinical studies comparing the effects of different interocclusal recording materials on reproducibility of protrusive settings in semiadjustable articulators have not been studied much. Hence, the present clinical study was conducted to comparatively assess the effects of three commonly used interocclusal recording materials; namely wax, polyvinylsiloxane, polyether in obtaining HCI values in two commonly used semiadjustable articulators; namely Hanau Wide-Vue (arcon) and Dentatus ARH type (non-arcon). Materials and methods One healthy female patient with intact dentition and no signs and symptoms of TMJ problems was selected for the study. With the help of a custom-made protrusive guide, 10 individual protrusive records for each of the interocclusal recording materials were made. These records were used for programming the two articulators and the respective HCI values were noted. The results obtained were tabulated and subjected to statistical analysis. Results The HCI values obtained using each of the interocclusal recording materials in both the semiadjustable articulators was found to be statistically significant. Among the materials polyether gave the highest values with less variability and wax gave low values with greater variation. Conclusion The results of this study indicate that HCI values vary both according to the type of interocclusal recording material employed and the articulator selected.

Reproducibility of jaw movements in patients with craniomandibular disorders

It has never been investigated, if mandibular movements of patients with craniomandibular disorders (CMD) result in a lower reproducibility of dynamic functional parameters which are used for the individual articulator setting. The aim of the present study was to compare the reproducibility of electronically registered functional parameters in patients with CMD and in a control group. Dynamic functional parameters were recorded in 30 patients and 30 volunteers with a computerized ultrasound system (ARCUSdigma). The whole registration was performed three times during one session and three times at a second session 1 week later. The horizontal condylar inclination in the patient group gave a standard deviation of 2.17 degrees +/- 0.95 degrees , indicating poorer reproducibility than in the volunteer group, for which the standard deviation was 1.37 degrees +/- 0.42 degrees . The reproducibility of measurements of the Bennett angle was also poorer in the patient group than in the volunteer group, with standard deviations of 1.70 degrees +/- 0.62 degrees and 1.22 degrees +/- 0.40 degrees , respectively. The standard deviations calculated for determination of incisal inclination during laterotrusion was 3.02 degrees +/- 1.49 degrees for patients and 2.30 degrees +/- 1.17 degrees for volunteers. The standard deviations for incisal inclination during protrusion was 2.02 degrees +/- 0.95 degrees for patients and 2.06 degrees +/- 1.82 degrees for volunteers. The reproducibility of measurement of horizontal condylar inclination, Bennett angle and incisal inclination during laterotrusion therefore showed significantly lower reproducibility in the patient group than in the volunteer group (P < 0.05). The overall reproducibility of the measurements was nevertheless good in both groups, with standard deviations under 3.1 degrees , so that an individual setting of an articulator seems useful even in patients with CMD.

Axiographic findings in patients undergoing orthodontic treatment with and without premolar extractions.

Mechanical axiography was performed on 49 (37 female, 12 male) patients prior to orthodontic treatment, after removal of the fixed appliance, and at the end of retention. Twenty-five subjects (mean age 12.8 years) underwent orthodontic treatment without premolar extractions (group 1) and 24 subjects (mean age 13.5 years) with premolar extractions (group 2). The axiographic tracings of the protrusive movements were analysed using a digitizer and specially designed software. A statistically significant increase (P < 0.05) in the values for horizontal condylar inclination (HCI) was found for both groups over the entire observation period. Group 1 showed a higher increase (P < 0.05) between the beginning of treatment and removal of the brackets, and group 2 between bracket removal and the end of retention. At the end of retention, a similar increase in HCI values was found for both groups. Over the observation period, the frequency of pathological axiographic findings decreased, which seems to be a positive effect of orthodontic treatment.

An in vitro evaluation of the reliability and validity of an electronic pantograph by testing with five different articulators

Statement of problem The degree of reliability and validity of a new electronic pantographic instrument, the Cadiax Compact, has not been established. Purpose The purpose of this study was to test the reliability and validity of the electronic pantograph in calculating condylar settings for 5 different articulators (Denar D5A, Denar Mark II, Whip Mix 8500, Hanau Modular, and Panadent PCH). Material and methods Pantograph sensors were mounted to each articulator with custom-made mounting devices. Border movements were made on each articulator with known condylar settings to produce readings at 3-, 5-, and 10-mm condylotrack distances. The condylar settings investigated included horizontal condylar inclination (HCI), immediate mandibular lateral translation (IMLT), progressive mandibular lateral translation (PMLT), top wall, and rear wall. Reliability was assessed by the relative size of standard deviations. Validity was tested with 1-way analysis of variance and the Tukey HSD Test (α=.05). Results The reliability readings for the condylar settings at the 10-mm condylotrack distance, for the most part, were more consistent than those at the 5-mm distance, which, in turn, were more consistent than those at the 3-mm distance. When there were exceptions to this trend, the differences in standard deviations were very small (0.006 mm for IMLT, 0.03 and 0.12 degrees for HCI). When comparing validity between the condylotrack distances, the smallest deviations, in general, were found at the 10-mm distance, the next smallest at the 5-mm distance, and the largest, at the 3-mm distance for HCI. For PMLT, in general, the 10-mm and 5-mm deviations were smaller than the 3-mm deviation. For IMLT, there was no significant difference between the 3-, 5-, and 10-mm deviations. In analyzing validity between the articulators, the smallest deviations from the preset values, in general, were found with the Denar Mark II. Conclusion The standard deviations for assessing reliability and the mean deviations for assessing validity were both relatively small in comparison to the average values of the condylar determinants. Therefore, the electronic pantograph was determined to be both reliable and valid.

A comparative analysis of optical and conventional axiography for the analysis of temporomandibular joint movements

Statement of problem Currently available systems for pantographic tracing are heavy, bulky, and can interfere with jaw movements. Purpose This study describes the development and clinical application of optoelectronic axiography designed to overcome system inherent problems of conventional bulky frame-based registration axiography. The purpose of this study is the comparison of the newly developed system and conventional axiography. Material and methods Three-dimensional recordings of condylar pathways were acquired by means of infrared digitizers interfaced to newly developed software. Ten distinct curves in each of 10 subjects were recorded by synchronous optoelectronic axiography (100 tracings) and by conventional axiography (100 tracings). Usually, two 3-dimensional (3D) light weight sensors are provisionally fixed to the facial surface of a maxillary and mandibular incisor by means of a single orthodontic bracket. To allow for direct comparison of all 100 pairs of curves in this study, the 3D sensors of the optoelectronic system were attached to the bulky double face-bow system of the axiograph. The conformity of tracings (protrusion, opening/closing, mediotrusion, and laterotrusion) was evaluated by means of correlation analysis. Resulting axiographic recordings from both systems were evaluated by 3 experts (dentists, experienced in axiographic investigations, who were blind to the source of the data), focusing on standardized qualitative criteria of the recordings (homogeneity/smoothness, pathway-characteristics, excursion, and left/right-symmetry). After testing for normal distribution of the ratio scaled data (length of pathway, horizontal condylar inclination [HCI], Bennett angle) with the Kolmogoroff-Smirnov test (α=.01), axiographic curves were quantitatively compared by means of an intraclass correlation coefficient ([ICC] α =.01). The Wilcoxon test (α=.01) was used to evaluate equivalence of ordinally scaled values (homogeneity of tracings) and Cohen's Kappa was used to compare excursion and left/right symmetry. Results High correspondence between curves recorded by conventional and optoelectronic axiography was observed. The mean differences of lengths between the protrusive, opening/closing, and mediotrusive pathways were 0.0 mm, 0.6 mm, and 0.1 mm, respectively. Pathways and values for HCI were found highly correlated (pathways: 95% CI of ICC 0.9776-0.9908; HCI: 95% CI of ICC 0.8641-0.9597). The 95% CIs for differences of pathways, HCI-value, and Bennett angle were −0.1mm/0.3mm, −3.4 degrees/1.9 degrees, and −2.8 degrees/4.8 degrees, respectively. Pathway characteristics also corresponded well (Cohen's Kappa: 0.73 for symmetric and 0.72 for asymmetric movements), 0.77 for left/right symmetry, whereas other characteristics showed less significant correlation (Cohen's Kappa of excursion: 0.21 for symmetric and 0.09 for asymmetric movements, homogeneity: 0.08 for symmetric and 0.15 for asymmetric movements). Conclusion Within the limitations of this study, optoelectronic axiography proved to be an applicable, promising technique, leading to diagnostic interpretations equivalent (with respect to the CIs) to conventional axiography.

Accuracy of recording horizontal condylar inclination and Bennett angle with the Cadiax compact.

This study assessed the accuracy of an electronic hinge axis tracing device (Cadiax compact) in measuring the horizontal condylar inclination (HCI) and the Bennett angle. The hinge axis movements were simulated with an articulator to which the hinge axis tracer was attached. On the articulator the pre-set HCI values were 20 degrees, 40 degrees and 60 degrees, the pre-set Bennett angles were 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees. The maximum measuring errors ranged from 0 to 3.4 degrees (in average 1.2 degrees ) and yielded statistically significant differences between articulator setting and Cadiax compact measurement (P < 0.05) except the HCI of 40 degrees and the Bennett angle of 0 degrees. Because of the small range of the maximum measuring error the Cadiax compact represented reasonable accuracy for clinical application in anterior guidance restorations.

顔面非対称患者の正貌骨格形態と下顎頭運動路の関連

It has been reported that skeletal facial asymmetry is correlated with condyle path asymmetry on protrusive movement. In this article, we investigated the degree and the direction of the condyle path asymmetry on open, protrusive, and lateral movements, and their relationship with skeletal asymmetry in the frontal dimension.The subjects were 35 patients with various facial patterns, (26 females, and 9 males ; mean age, 21.9±4. 8years). Standardized PA cephalograms were used for morphological analysis. The linear and angular measurements were based on the x-y coordinates, the Lo-Lo' plane as the x-axis, and the vertical line through Nc as the y-axis. Reference points, such as Mo, Mo', Go, Go', and Me, were chosen to analyze horizontal and vertical skeletal asymmetries. The measurements were used as skeletal asymmetry variables.Condylar movements were recorded with a computeraided Axiograph (CADIAXR, Gamma). Both horizontal condylar inclination (HCN) on the sagittal plane and the Bennet angle (BEN) on the horizontal plane were measured 5 mm from a reference point (RP), and the shortest distance between RP and the most translated position of the condyle (DIS) on the sagittal plane was measured. The difference between the right and left condyles was calculated and used as a condylar path asymmetry variable. Stepwise linear regression analysis was performed to pick up a valid skeletal asymmetry variable for describing the condylar path asymmetry variable.On open movement, stepwise linear regression analysis selected only deviation of Me as a valid parameter for the HCN difference between both condyles. Deviation of Me was also revealed to be a valid parameter for explaining the differences in HCN, BEN, and DIS on protrusive movement, and the differences in HCN and DIS on lateral movement. Upper dental arch asymmetry and horizontal cant of the occlusal plane were found to be effective parameters for HCN difference on protrusive movement. Upper dental arch asymmetry was also an effective parameter for BEN difference on lateral movement. These results indicated that horizontal and vertical skeletal facial asymmetry had a relationship with condylar path asymmetry in every mandibular movement.

Guided versus unguided mandibular movement for duplicating intraoral eccentric tooth contacts in the articulator

Statement of problem. The extent to which intraoral excursive tooth contacts are duplicated correctly in the articulator is constantly being investigated. Purpose. This study evaluated whether data from unguided or guided hinge axis movement are superior in duplicating excursive tooth contacts. Material and methods. Intraoral records of tooth contacts from intercuspal position to 4 mm protrusion and laterotrusion were obtained from 50 subjects by using occlusogram wax. These movements were simulated in a SAM2 “P” articulator using horizontal condylar inclination and Bennett angle from recorded guided and unguided mandibular movements. Occlusograms were compared with contacts generated by the articulator. Results. On average, the articulator duplicated approximately 73% of intraoral protrusive and 81% of intraoral laterotrusive contacts for up to 4 mm of movement, using either data from unguided or guided movements. Both movements yielded identical means and no significant difference of duplicated contacts. However, individual differences scattered within approximately ±32%. Conclusion. Exclusive recommendation of guided movement can be questioned for accurate imitation of dynamic tooth contacts. In addition to the type of movement, other factors must be detected to enhance articulator adjustment and workings. (J Prosthet Dent 1999;81:14-22.)

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.