Fracture behaviour of directly restored pulpotomized primary molars with biomimetic versus conventional bilayered structure; An in-vitro study.

Abstract

Objectives:The aim was to evaluate fracture behaviour of directly restored pulpotomized primary molars with two biomimetic and one bilayered structures. Besides, impact of these structures to restore strength of sound molars was evaluated Materials and Methods: Fifteen sound and forty-five carious extracted second primary molars were selected to be used in this study. The 15 sound molars were left intact without any preparation as Group A (Intact structure). While standardized access cavity preparation and pulpotomy procedures were performed on 45 carious molars. The pulpotomized molars were divided randomly and equally (n= 15) according to final composite restoration structure into Group B (everX Posterior + G -aenial Posterior) and Group C (everX flow + G -aenial Posterior) as biomimetic structure and Group D (Filtek Bulk Fill Flow + Filtek Z250 XT) as conventional bilayered structure. Each composite resin and its adhesive were applied with strict adherence to manufacture instructions. After thermocycling , each molar was tested for fracture resistance using instron testing machine at 0.5 mm/ min crosshead speed with 4.5 mm rounded end metallic cone. The compressive force inducing fracture in each specimen was recorded in Newton(N) and the fracture pattern was examined visually with aid of magnifying lens. Statistical analysis was done using ANOVA and post-hoc tests at 5% of significance.Results: Mean fracture resistance value of group A (intact structure) was highly statistically significant than that for groups B and C (biomimetic structures) or group D (bilayered structure) (p<0.05). Despite the high fracture resistance values of biomimetic structure groups (groups B and C) than that of bilayered structure group (group D), no statistically significant difference was found on comparison between them (p>0.05). Majority of fracture pattern in intact group was type I, while majority in biomimetic groups and bilayered group was types II and III respectively.Conclusions: Biomimetic restoration showed most favorable outcomes for pulpotomized molars regarding strength and fracture pattern.