Comparison of shear bond strength of brackets bonded with four different bonding protocols at different time intervals; An in vitro study

Abstract

Objective: To test shear bond strength and mode of debonding of brackets bonded using a traditional orthodontic adhesive (Transbond XT), self- adhesive material (Heliosit) and self-etch s after 15 minutes, 24 hours and following aging and thermocycling. Materials and Methods: One hundred and eighty upper first premolar teeth extracted for orthodontic purposes were used in this study. The specimens were equally and randomly allocated into four groups. TXT group (Transbond XT; n=45); HS group (Heliosit group; n=45); VF group (Vertise Flow; n=45) and (VF+P) (Vertise Flow with phosphoric acid etch; n=45). Each group was randomly and equally divided into three equal subgroups; First subgroup (n=15) shear bond strength was tested after 15 minutes of bracket bonding, second subgroup (n=15): shear bond strength was tested after storage in distilled water at 37°C for 24 hours and third subgroup (n=15 per group): shear bond strength was tested after specimens storage in distilled water at 37°C for 6 weeks and subjected to 1000 thermal cycles between 5-55°C. Adhesive remnant index (ARI) was recorded for each specimen and its mean was compared between different groups. Results: Significance level was set to α= 0.05. Vertise flow (either with or without enamel pre-etching) and Transbond had acceptable bond strength at 15minutes debond testing. Heliosit adhesive had a significantly lower SBS at 15 minutes debond. Transbond XT had a significantly higher (SBS) compared to the other 3 groups at 24 hours debond.