Abstract

COMPARISON OF FRACTURE RESISTANCE OF CAD/CAM INTERIM BRIDGE AND CONVENTIONAL INTERIM RESIN BRIDGE

Alaa Hussein Jasim*, Dr. Lateef Essa Alwan and Akhlas Zeid Abood

Abstract

Background: Interim fixed restorations are important to protect pulp, protect abutment after preparation, assess the parallelism, preventing migration of abutments and improve esthetic appearance in anterior region. Moreover interim prostheses could assist in periodontal therapy, orthodontic therapy, occlusal treatment and implant therapy. Essentially, it should have good resistance to fracture, especially when used for extended treatment periods. Objective: evaluate and compare the fracture resistance between Cad/ Cam interim bridges and conventional interim bridges. Material and Method: Ideal model of full dental arch was used as a pattern to simulate three Units Bridge with (maxillary first molar and maxillary first premolar) as abutments. This model was then duplicated and resulted cast sectioned by cutting disk to produce a small cast that limited to the prepared bridge area only. This cast was then duplicated and poured by molten wax to produce wax pattern that was modified before casting with the use of radial shoulder finishing line design instead of chamfer finishing line that came with the original ideal model. From this wax pattern, metal master model was produced by lost wax technique. Thirty two impressions for master model with two stage putty- wash impression technique were taken and poured with die stone to produce thirty two stone models. The stone models then divided into four groups with eight models per group, according to the material and fabrication technique used to produce interim bridge and as follow: Group 1: Ivoclar CAD CAM (Telio CAD); Group 2: Ivoclar conventional (Telio Lab); Group 3: Vita CAD CAM(Vita CAD-Temp) and Group 4: Vita conventional (Vita VM CC). In fracture resistance test, each interim bridge was seated over master model then subjected to three points bending test using universal testing machine at cross head speed of (1mm/min.) till fracture occurred. Results: The results showed that the highest mean value of fracture resistance was recorded by Group 1 (735.9N) followed by Group 3 (585N), Group 2 (508.8N) and Group4 (460.8N) respectively. Concerning fracture mode, the connector area showed the weakest and most frequent area of fracture. Conclusion: CAD CAM groups had better fracture resistance values than conventional groups with Ivoclar Telio CAD material showing the highest fracture resistance means value. The most frequent failure mode was within the connectors of interim bridges. CAD CAM fabricated interim bridges are recommended to be used for long term and long span interim treatment.

Keywords: CAD CAM Interim Bridge, conventional, Fracture Resistance.