Condylar guidance: correlation between protrusive interocclusal record and panoramic radiographic image: a pilot study

Purpose: 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. Materials and Methods: 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. Results: 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. Conclusion : 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.     

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. Aims and objectives: 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: 20–29 years, Group II: 30–39 years, Group III: 40–49 years, Group IV: 50–59 years. 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.     

解析法分析(牙合)架参数测量误差导致的前伸(牙合)误差

目的:理论计算ARCUSdigma系统测量架参数误差所导致的牙合架前伸牙合误差。方法:通过推导数学公式,建立解析法分析下颌第一磨牙区域前伸误差的方法。并计算ARCUSdigma系统对各前伸髁导斜度、切导斜度设定值的最大、最小和平均测量值所导致的前伸牙合误差。结果:前伸髁导斜度小于30°时,最大、最小和平均测量值导致的咬合误差均小于0.2mm;而切导斜度的最大、最小测量值导致的咬合误差稍大。当切导斜度为80°、前伸髁导斜度达到45°时,测量平均值也会导致较大的前伸误差。结论:采用ARCUSdigma系统获取牙合架参数误差所导致的前伸误差较小。如前伸髁导斜度小于30°,不需多次测量;而前伸切导斜度应取多次测量结果的平均值。对于大于30°前伸髁导斜度、大于70°切导斜度的测量值的采用,则要慎重。     

The Effect of the Articulator Settings on the Cusp Inclines as Measured by a Coordinate Measuring Machine

Purpose The purpose of the study was to learn the effect of changes in the articulator settings on the cusp angles during working, nonworking, and protrusive movements; the purpose was also to determine the ability of the coordinate measuring machine to measure the movements. Materials and Methods The condylar angles and the anterior guide angles on a Hanau 96H2 articulator (Teledyne Hanau Corp, Buffalo, NY) were varied; 432 working, nonworking, and protrusive cusp angles were measured at the first molar by a coordinate measuring machine. Results The data from the coordinate measuring machine was used to produce formulas. The formulas were used to calculate the working, nonworking, and protrusive cusp angles that will occur as a result of 72 different articulator settings. Conclusions The coordinate measuring machine is useful for making measurements of articulator movements. Additional research may measure the movements of other articulators or compare articulators (such as the arcon and nonarcon).     

Effects of changes in articulator settings on generated occlusal tracings. Part I: Condylar inclination and progressive side shift settings

An occlusal scribing device attached to a fully adjustable articulator was used to generate occlusal tracings. The tracings were analyzed to determine the effect changes in progressive side shift and condylar inclination settings had on molar occlusal morphology. The progressive side shift adjustment affected the cusp height and ridge and groove position, primarily in the nonworking excursion. The condylar inclination adjustment affected the cusp heights in the protrusive and nonworking excursion without affecting the working excursion.     

Effect of interocclusal records on the condylar path of the articulator

Although there are studies on materials used for interocclusal records, there are no scientific data how the condylar path is influenced by the positional interocclusal records. The purpose of this in vitro study was to determine the effects of different interocclusal mediums on condylar inclination of the articulator. The materials selected for this experiment were: two addition type silicone pastes, two silicone putty materials and two waxes. The samples of protrusive records were performed on a Quick-Master semiadjustable articulator (FAG Dentaire). The same pre-established eminentia angles were used during the experiment for each type of materials. To improve the control of the condylar angles a protractor was mounted to the upper member of the articulator at right angels to each condylar fossa housing. A stylus moving simultaneously with the condylar fossa marked the eminentia angle on the protractor. 108 interocclusal records were performed and in 24 hours they were returned to the articulator. Then the articulator was adjusted and the settings of the eminentia angle were recorded. Numerical deviations between the pre-established and the adjusted settings in degrees were subjected to statistical analysis. The results indicated that these deviations for addition type silicones were significantly smaller than that of the other materials. The two waxes proved to be the least accurate materials. It is concluded that the condylar inclination is influenced by the properties of the registration materials, which may increase the shortcomings of the protrusive bite records.     

Setting the sagittal condylar inclination on a virtual articulator by using a facial and intraoral scan of the protrusive interocclusal position: A dental technique

Setting the condylar inclination of a dental articulator enables the delivery of prostheses without occlusal interferences. This technique article describes obtaining the sagittal condylar inclination (SCI) by using a facial and an intraoral scan of the protrusive interocclusal position. The SCI can be used on a virtual articulator in dental computer-aided design (CAD) software programs, which can facilitate the fabrication of functional prostheses without occlusal interferences.     

Analysis of the lateral condylar adjustment of nonarcon semiadjustable articulators

An analysis of the lateral condylar inclination adjustment of the slot-track semiadjustable articulator was performed by using a fully adjustable articulator as a simulated patient. Pantographic tracings were made and transferred to the semiadjustable articulator. The lateral condylar inclination of the articulator was then rotated to allow it to follow the pantographic tracings as closely as possible. The results indicate that the Hanau formula or an arbitrary setting of 15 to 20 degrees does not provide the most accurate articulator setting possible.     

Reproducibility of lateral excursive tooth contact in a semi-adjustable articulator depending on the type of lateral guidance

The purposes of this study were (i) to compare the reproducibility of lateral tooth contacts of casts mounted in a semi-adjustable articulator when condylar guidance was set by different methods and (ii) to assess the margin of error of the variations of condylar guidance without changing lateral tooth contacts, depending on the type of lateral guidance. In subjects with different types of lateral guidance, intraoral lateral tooth contacts identified with occlusal registration strips were compared with those identified by use of a semi-adjustable articulator, setting the condylar guidance in four different ways: using protrusive wax wafers, by axiography and by adding and subtracting 5 degrees from the value of condylar guidance obtained by protrusive wax wafers. Tolerance to variations of condylar guidance without changing lateral tooth contacts was determined by increasing and decreasing the value of condylar guidance until lateral tooth contacts changed. Different ways of setting condylar guidance on a semi-adjustable articulator give rise to different values of condylar guidance in the same subject. The occlusal repercussions of these variations of condylar guidance values depend on the type of lateral guidance. Canine protection had the greatest tolerance to variations in the setting of condylar guidance without changing lateral occlusal contacts.     

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.     

A comparison of protrusive interocclusal records to pantographic tracings

The rationale for recording protrusive mandibular movement is to accurately adjust an articulator. Techniques to record condylar inclination include radiographic interpretation, extraoral tracings, and intraoral recording materials. This study compared the protrusive settings on an articular adjusted by a pantograph to protrusive settings recorded by two intraoral recording materials, one a polyvinyl siloxane material and one a laminated, metalized wax. Pantographs were completed for 20 patients by using a kinematic hinge axis and conventional pantographic techniques. The patients also had three protrusive interocclusal records made with two intraoral registration materials completed and averaged. The average condylar inclination recorded with a pantograph (29.5 degrees) was greater than the recording by either intraoral registration material. Standard deviations ranged from 4.1 degrees to 6.6 degrees. An analysis of variance showed that the condylar inclination recorded by wax was statistically less than recorded with a pantograph. A comparison between the pantograph and the polyvinyl siloxane displayed no statistically significant difference in recording condylar inclination.     

Recording sagittal condylar angles using a mandibular facebow

summary The aim of this study was to determine the average sagittal condylar inclination angles of dentate subjects using a mandibular facebow with pencil tracing styli, to relate these angles to values assigned to articulators, and to assess the repeatability accuracy of drawing a tangent to a traced curve. The right and left sagittal condylar inclination angles of 103 subjects were recorded using a mandibular facebow with pencil tracing styli which marked a graph card during protrusive excursions. Tangents to the tracings were measured with a protractor allowing assessment of reproducibility. The mean left and right sagittal condylar inclination angles were 32° and 31.5°, respectively, with no significant differences ( P =0.609). Individual right and left measurements within each group showed significant differences ( P = 0.0000). The mean of the tangents drawn through three sagittal condylar angle tracings by 10 operators was 33.3°, and the mean of 10 tangents drawn through the same three tracings by one of the authors was 32.9°, with no significant difference ( P = 0.634). The average sagittal condylar inclination angles found in this study are in agreement with those reported in the literature. In fixed sagittal condylar angle articulators 30° appear to be an appropriate setting. The reproducibility of this method of recording sagittal condylar inclination angles was found to be accurate for the individual operator and between operators.     

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 new semiadjustable articulator. Part III. An investigation of the capability of the Hanau XP-51 articulator.

A new semiadjustable articulator, the Hanau XP-51, was investigated by comparing its movements at the cusp level to those of a Stuart articulator when guided by straight condylar elements. No clinical trial was undertaken in this investigation, and no mandibular movements were registered on the Stuart articulator for transfer to the Hanau XP-51 articulator. A method of comparison and mathematical formulae were described whereby specific angles were calculated for both articulators. All tabulated angles were correlated by determining the least-squares slope of the observed angular variation as a function of the three independent variables in a computerized program. The standard deviation from these was calculated for each articulator, and the differences were found to be very small. It was concluded that the experimental Hanau XP-51 articulator could reproduce specific movements made by the Stuart articulator. Further, the adjustable posterior wall within the condylar housing was found to compensate for the lack of an adjustable intercondylar distance on this articulator.     

Comparative study of condylar settings of three semiadjustable articulators

The reproducibility of arcon semiadjustable Whip Mix, Denar Mark II, and Hanau 158 articulators was tested using multiple protrusive and lateral edge-to-edge wax interarch registrations made with an interocclusal device. Photographic and cephalometric tracings verified an identical angulation between the axis-orbital craniofacial reference plane and the maxillary occlusal plane for the subject and both the Denar Mark II and Hanau 158 articulators. This angle was 2.5 degrees less in the Whip Mix instrument. Three operators made three settings for each of 12 protrusive and 24 lateral interarch registrations for each articulator. Results showed significant differences between instruments. Whip Mix consistently gave the highest.angulations and Hanau 158 the lowest. For protrusive records there was no significant difference between examiners, but for lateral records a significant difference in examiner registration was found. For both protrusive and nonworking registrations, interaction was seen between instrument and operator and between instrument and registration, and a significant difference was seen between records. This study supports previous studies showing that semiadjustable articulators using interarch records have a low level of reproducibility and are subject to variables of instrument, operator, and occlusal records.     

骨性Ⅲ类偏颌患者髁突与(牙合)平面特征的CBCT研究

目的 利用锥形束CT(CBCT)测量分析骨性Ⅲ类偏颌患者髁突及(牙合)平面特征。方法 选取符合纳入标准的骨性Ⅲ类成年患者40例,所有个体按照颏下点偏离正中矢状面距离进行分组,分别测量各组左右两侧(牙合)平面角、髁突位置及形态,并对数据进行统计学分析。结果 骨性Ⅲ类偏颌患者的偏侧与对侧相比,(牙合)平面角、关节前间隙、关节上间隙、关节外间隙及髁突内外径差异有统计学意义(P<0.05),偏侧关节后位所占比例较大,下颌骨偏移量与偏侧髁突前间隙及对侧(牙合)平面角均呈正相关(P<0.01)。骨性Ⅲ类非偏颌患者的左右两侧(牙合)平面角、髁突位置及形态指标之间差异均无统计学意义(P>0.05),关节以前位、中位为主。结论 骨性Ⅲ类偏颌患者左右两侧(牙合)平面角、髁突位置及形态不对称,偏侧(牙合)平面角及髁突内外径较小,髁突向后下内方移位,且偏颌程度与(牙合)平面角及髁突位置之间存在相关性。     

Measurements of the sagittal condylar inclination: intraindividual variations

Aims: Sagittal condylar inclination is an important parameter during fabrication of prosthetic restorations. Existing data about intraindividual variations of sagittal condylar inclination are scarce. The purpose of this study was to investigate intra- and interindividual variations of the sagittal condylar inclination, depending on the position of the condyle in the temporomandibular joint.

Methodology: The study included 51 subjects with Angle’s Class I occlusion (21–32 years of age, mean 25·1). Measurements were done using an electronic axiograph. After a paraocclusal tray was fixed in the mouth, every subject had to make three protrusive movements, from which the device’s software calculated the mean left and mean right sagittal condylar path. The mean left and right condylar path of each subject was divided into three equal sequences, based on whole condylar path length. Condylar inclination values for the first, second and third movement sequences were calculated.

Results: Results showed significant differences between movement sequences (P<0·05). For the left joint, condylar inclination values in the first condylar movement sequence demonstrated, on the average, 14·4% higher values compared to the second movement sequence, and 39·2% higher values than in the third movement sequence. For the right joint, the first condylar movement sequence demonstrated, on the average, 15·8% higher values compared to the second movement sequence, and 41·5% higher values than the third movement sequence.

Conclusions: Results suggest that condylar movement in the sagittal direction is not uniform. Mean left and mean right condylar inclination values do not necessarily describe the actual condylar path, nor do they give adequate information for articulator setup. Left–right side condylar inclination differences greater than 10° can be considered as normal.     

A comparative study to measure the condylar guidance by the radiographic and clinical methods

PURPOSE

The study was conducted to compare the radiographic and clinical methods of measuring the horizontal condylar guidance (HCG) values.

MATERIALS AND METHODS

The condylar guidance was measured using the radiographic (CT scan) and three clinical methods i.e. the wax protrusive records, Lucia jig record and intraoral central bearing device in 12 patients aged between 20-40 years irrespective of sex. The records were taken and transferred on the semi-adjustable articulator to record the HCG values. The CT scan was taken for 3D reconstruction of the mid facial region. Frankfort horizontal plane (FHP) and a line extending from the superior anterior most point on the glenoid fossa to the most convex point on the apex of articular eminence (AE) was marked on the CT scan. An angle between these two lines was measured on both right and left sides to obtain condylar inclination angle. Three interocclusal protrusive wax and jig records were taken and transferred to the semi adjustable articulator. Three readings were recorded on each side. Similarly the records were taken and transferred to the same articulator using the intra oral central bearing device to record the readings.

RESULTS

The statistical analysis showed insignificant differences in the HCG values between the right and left sides [(P=.589 (CT), P=.928 (wax), P=.625 (jig), P=.886 (tracer)]. The clinical methods provided low Pearsons correlation values [(R = 0.423 (wax), R = 0.354 (jig), R = 0.265 (tracer)] for the right as well as the left sides when compared with the CT values. Among the clinical methods, jig and wax method showed strong level of association which is statistically significant while the intra-oral tracer showed weak association with the other two methods.

CONCLUSION

The right and left HCG values were almost similar. The CT scan showed higher HCG values than the clinical methods and among the clinical methods, values obtained from all the methods were comparable.     

Sagittal condylar guidance as determined by protrusion records and wear facets of teeth.

The maxillary and mandibular casts of 45 healthy and dentulous subjects, with conspicuous wear facets on canines and molars, were mounted on a semiadjustable articulator. The sagittal condylar guidance was determined by two methods: (1) using a protrusion wax interocclusal record and (2) by matching the wear facets of opposing canines and contralateral molars. There was a substantial bilateral symmetry of the right and left sagittal condylar guidance angles using both methods. There were, however, significant differences between the mean angles of the two methods, about 31 degrees (protrusion record) versus about 24 degrees (wear facets). This, in association with rather low coefficients of linear determination, suggested that the two methods of recording the sagittal condylar guidance angle were based on totally different phenomena.     

全口义齿在(牙合)架上前伸运动的计算机三维模拟

目的：探索建立能将三维模拟全口义齿在（牙合）架上进行前伸运动的算法模块。方法：应用激光三维扫描和重建技术，建立全口义齿人工牙列模型，采用Matlab6．5数学计算分析软件，并结合空间解析几何原理，对全口义齿在（牙合）架上的前伸运动进行数学建模和运动模拟。结果：建立了用于模拟全口义齿在（牙合）架上三维前伸运动的算法模块．并在实际病例进行验证。结论：该方法的设计思想可行，为定量研究义齿动态咬合情况奠定了基础。