Résumé
Objectives: The goal of every prosthetic management is to simulate nature and be in harmony with nature within the physiological limits. The occlusal forces on a fixed dental prosthesis are transmitted to the surrounding structures through pontics, connectors and retainers and more stresses are seen at the connector region. To analyze the stress patterns in cast and soldered connectors between the two pontics and between the retainer and pontic of a four unit fixed dental prosthesis on axial and non axial loading and also to observe and ascertain the need to modify the design of the rigid connectors. Materials and Methods: Subsequently four models each of cast and soldered connectors with cylindrical and triangular design, of dimension 3 × 4 mm and thickness 0.5 mm was designed for the study. The first premolar and second molar were considered as the abutments and 2 nd premolar and 1 st molar as the pontics. The analysis was done using ANSYS version 8.0 software and by placing axial and non-axial load of 40 Newtons each. Results: Von Misses stresses were observed at the connector region between the two pontics, especially in the cervical region. Conclusion: The cylindrical cast connectors showed less stress in comparison to triangular design and the difference in the stress distribution of cast and soldered connectors were marginal. Clinical Significance: The occlusal forces on a fixed dental prosthesis are transmitted to the surrounding structures through pontics, connectors and retainers with maximum stresses concentrated at the connectors. Hence this three-dimensional finite element analysis study investigated stress distribution in a four unit posterior fixed dental prosthesis, having cylindrical and triangular connector designs.
Résumé
Background: Establishment of a proper occlusal plane is needed for developing an occlusion that is compatible with the biomechanics of a stomatognathic system. There has been a great deal of controversy regarding the anatomic reference point/s taken for identifying the Camper's plane (Ala-Tragus) to which the occlusal plane is oriented parallel in regular complete denture Prosthodontic practice. There has been no study in literature to correlate the occlusal plane to the Camper's plane in various skeletal malocclusions using landmarks on a lateral Cephalogram. Aim : The aim of the study isto determine the relative parallelism of the occlusal plane to ala- tragal lines in various malocclusions. Methodology: A total of sixty subjects belonging to Class I, Class II and class III malocclusions were selected for the study. Markings with radiopaque marker of 1 mm diameter were adhered against the superior, middle and inferior border of the tragus and against the lower borer of ala of the nose. Lateral cephalograms were obtained for all of the pateints. Tracing was performed for all of these radiographs. Statistical Analysis Used: Analysis of Variance (ANOVA) test and Post-Hoc test of Bonferroni were used to compare the angles formed at the superior, middle and inferior borders with the occlusal plane. Results: The result from the present study showed that in Class I and Class III malocclusion, the line drawn from the lower border of ala of the nose to the inferior position of the tragus (Camper' plane C) was relatively parallel to occlusal plane; and, in Class II malocclusion, the line drawn from the lower border of ala of nose to middle border of tragus (Camper's plane B) was relatively parallel to occlusal plane.