Evaluation of glass fibre post with varying ferrule lenghts

Statement of problem: The presence of ferrule is hypothesized to protect the tooth from wedging stresses in post restored teeth. Restoration design must provide enough strength to restoration and to abutment teeth to resist occlusal forces. It is important to evaluate the optimum ferrule length in various post and core restorations that must be incorporated in endodontically treated teeth to increase its fracture resistance. Purpose: The purpose of this study was to evaluate the effect of different length of ferrule on fracture resistance and mode of failure of endodontically treated teeth restored with two different post systems, including glass fibre post and composite system and Ni-Cr cast metal post and core system. Methods: Eighty freshly extracted human maxillary central incisors were endodontically treated. Teeth were randomly divided into two groups of 40 teeth each. Each group was further subdivided into four subgroups of 10 teeth each depending upon the length of ferrule preparation i.e., 0mm, 1mm, 2mm and 3mm. The Group A was restored with glass fiber-reinforced post and composite resin core (GFRP) and the Group B was restored with Ni-Cr cast post and core (CP). All the specimens were loaded to fracture using a universal testing machine and mode of failure was recorded by visual inspection. Data were statistically analyzed. Results: The mean fracture resistance was found to be highest at ferrule length of 2mm in both groups. Conclusions: This in vitro study demonstrated that the optimum ferrule length required is 2mm.