Morphological changes of the root surface and fracture resistance after Treatment of root fracture by CO2 laser and glass ionomer or mineral trioxide Aggregates

摘要

Objectives: Background and objectives: This in vitro study evaluated the morphological changes of the root surface and fracture resistance after Treatment of root cracks by CO2 laser and glass ionomer or mineral trioxide aggregates (MTA). Materials and methods: Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5mm~2 and a depth of 1.5mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scaning electron microscope was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Tukey s Honestly Significant Difference (HSD) tests. Results: SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cemetum and glass ionomer and melted masses and globular like structure between cemetum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Conclusions: Glass ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO laser increase the resistance of the teeth to fracture.