Incorporation of fiber reinforcement to enhance mechanical properties of bisacrylic resin temporary bridges

Abstract

Aim: To evaluate the effect of fiber reinforcement on flexural strength (FS), marginal adaptation (MA) and resistance to fatigue (RF) of bisacrylic resin provisional bridges. Methods: Two metal cores fixed to a metal base at a distance of 10mm of each other reproduced a simulated cast for a three-teeth bridge with an extracted molar. A metal bridge was manufactured for this cast, representing teeth 45, 46 (phantom) and 47. This master-piece was used to obtain a polyether matrix (Impregum Regular, 3M Espe, Seefeld, Germany) for the production of provisional bridges for the three treatment groups using the following materials: A) PMMA; B) Bisacrylic resin (ProTemp 3, 3M Espe, St. Paul, USA); C) Bisacrylic resin + fiber reinforcement (Interlig, Angelus, Brazil). For each test, samples were supported using the metal base as a fixed platform. FS was assessed using a Universal Testing Machine (Digimess MX5000) at a crosshead speed of 1mm/min. FS was expressed in Newtons as the load at fracture of the samples. MA was evaluated as the distance between the distal-cervical margins of the crowns and the shoulder of the metal cores, at three moments of load charge (initial, 500N and 800N). RF was tested using dynamic forces as the number of cycles until fracture using a load charge of 80% of the static maximum force. Mann-Whitney U test (p<0.05) was used for statistical analysis. Results: Mean FS values were 810(80)N, 800(20)N y 990(20)N for groups A, B and C respectively. Bisacrylic resin groups resisted significantly more cycles until fracture than PMMA, being group C the one that resisted the most. Regarding MA test, a great dispersion of values among the three groups was observed. Conclusion: Addition of glass-fibers increased FS and RF of bisacrylic provisional bridges without an effect on MA