Abstract: The position of mandible in centric relation is the initial position in prosthodontic rehabilitation. This fact is especially significant today when, due to development of implantology, the use of osseointegrated prostheses is increasingly discussed. The aim of the study is to define if the peak of the articulating surface of mandible in centric relation position is directed towards the zenith of madibular fossa, or is in the retroposition. The research was conducted on macerated human sculls in anthropometric system, based on objective measuring techniques and methods. The results showed that if the zenith of mandibular fossa is determined according to the vertical line of the Frankfurt horizontal, the peak of the mandibular caput articulating surface is in retroposition. The relation of the lower joint surface to the mandibular fossa zenith is the same on both right and left side. The correlation coefficient demonstrates a high correlation between the sides, highly significant with probability level of p<0,01. If the peak of mandibular fossa is determined according to the vertical line of the Frankfurt horizontal, the peak of the articulating surface of mandibular caput is in retroposition in relation to the peak of the upper jaw surface. This original scientific work will help better understanding of x-ray analysis and understanding of relationship of TMJ surfaces, what is necessary for treatment of TMD and occlusal imbalances.

Abstract: Reproducibility of the centric relation position for patients with temporomandibular disorders (TMD) is not documented in the current literature. It was the objective of this study to assess clinical variability of the centric relation position for TMD patients with a muscle-determined technique by means of an anterior deprogramming device, the leaf gauge. A sample of 60 patients with signs of TMD was selected, 8 men (Mean age 28,6, SD 5,2) and 52 women (Mean age 30,5, SD 10,1). All patients were examined with the Research Diagnostic Criteria, including pain on movement and/or function, mouth opening, joint sounds and palpation of masticatory muscles. All 60 patients were allocated to one of the following diagnostic subgroups: myofascial pain, disk displacement with reduction, disk displacement without reduction, osteoarthritis, trauma. Twelve control subjects were taken from a previous study. Three sequential centric relation records were taken; the first one was used to mount a set of casts to an articulator. Criteria of precision were formulated beforehand: 2 out of 3 centric relation records had to be identical in a split-cast procedure. Variables XL and XR represented mandibular displacement in the sagittal plane, variables YL and YR in the transversal plane, and ZL and ZR in the vertical plane, on the left and right condylar level respectively. Variables XMIN, YMIN and ZMIN represented the minimal sagittal, transversal and vertical displacement left or right respectively. Likewise, variables XMAX, YMAX and ZMAX represented the maximal sagittal, transversal and vertical displacement left or right. XDIFF, YDIFF and ZDIFF represented the difference between the minimal and maximal values of X, Y and Z. The diagnostic subgroup trauma was excluded, because there was only one patient. The null-hypothesis of no between-group differences in within-subject and total variability was tested with an analysis of variance (ANOVA). The level of significance was set at 0.05. To minimize type I errors caused by multiple testing Scheffe's test was used to maintain an overall significance of 0.05. No significant difference between patients and control subjects could be found for variables XL, XR, YL, YR, ZR and ZL. Variables XMIN, YMIN, ZMIN, XMAX, YMAX, ZMAX, XDIFF, YDIFF and ZDIFF showed no significant differences. Scheffe's testing for the variables XL, XR, YL, YR, ZL and ZR, as well as the variables XMIN, YMIN, ZMIN, XMAX, YMAX, ZMAX, XDIFF YDIFF and ZDIFF showed no significant differences. The results of this study suggest no variability in centric relation position between TMD-patients and control subjects by means of the leaf gauge.

Abstract: Objectives: This article reported three patients developed anterior open bite seemed to be related to TMJ anterior disc dislocation without reduction(ADD WO R), but no evidence of condylar destructive or collapse and analyzed the craniofacial skeletal structure by means of cephalometric analysis. Results: All patients suddenly developed a centric relation/centric occlusion discrepancy, an increased overjet and an anterior open bite following ADD WO R. All patients had Angle's Class I occlusion and shallow bite, but they had skeletally Class III and Class II pattern and all were vertically significant hyperdivergent type. Conclusions: These 3 patients had characteristics of common facial morphology including: (1)Angle classification Class I and shallow bite, (2)high mandibular plane angle, (3)high gonial angle. Developed anterior open bite resulted from clockwise rotation of the mandible related TMJ ADD WO R, rather than a result from the eruption of posterior teeth. We hypothesize rotation may relate to attached direction of masticatory muscle.

Abstract: Despite comprising one of the routine duties of dental practitioners, the methods used for the determination of the vertical and horizontal jaw position differ considerably from dentist to dentist. For the overwhelming majority of patients, however, the techniques generally applied for the maxillomandibular relationship record appear to lead to acceptable results. No method seems to be clearly superior to the other. As far as the determination of the horizontal mandibular position (centric relation interocclusal record) is concerned, bimanual manipulation has shown to be particularly reliable. The decisive factor, apart from any preferred method, is that the chosen therapeutic mandibular position be reproducible for both the treatment provider as well as the patient.