Conditioning of enamel with Nd:YAG and CO2 dental laser systems and with phosphoric acid. An in-vitro comparison of the tensile bond strength and the morphology of the enamel surface.

Abstract

MATERIAL AND METHOD 1: The first stage of a three-stage in-vitro investigation used 146 maxillary incisors to identify optimum setting parameters for two CO2 and Nd:YAG standard laser systems applied in enamel conditioning for bracket bonding. 31 of the 75 parameter combinations investigated for the Nd:YAG laser and nine of the 71 investigated for the CO2 laser proved appropriate for further investigation of tensile strength. MATERIAL AND METHOD 2: In a second stage, tensile bond strength for the selected laser settings was determined in comparison to the conventional acid-etch technique for a further 210 teeth as the control group. The highest average tensile strength for the Nd:YAG laser was 4.1 MPa, with comparable values of 3.3 MPa for the CO2 Laser and 4.9 MPa for the acid-etch technique. MATERIAL AND METHOD 3: The third stage of the investigation involved comparative scanning electron microscopy of enamel surface morphology following laser application and acid-etching. The CO2 laser was found to produce craters of various dimensions, while the Nd:YAG laser produced honeycomb structures regionally similar to enamel samples from the acid-etch technique. The CO2 and Nd:YAG dental lasers tested produce enamel conditioning and tensile bond strength sufficient to meet the requirements of bracket bonding.