A New Laser-Processing Strategy for Improving Enamel Erosion Resistance

In the present study,a new automatic laser-processing strategy allowing standardized irradiation of natural tooth areas was investigated. the objective was to find a combination of laser parameters that could cause over a 600°c temperature increase at the enamel surface while not damaging enamel,avoiding temperature change above 5.5°c in the pulp and increasing enamel erosion resistance. seventy-seven bovine enamel samples were randomly divided into 6 laser groups and 1 negative control (c/no treatment/n = 11). a scanning strategy (7 × 3 mm) was used for the co2 laser treatment (λ = 10.6 μm,0.1-18 j/cm2) with different pulse durations - namely,20 μs (g20),30 μs (g30),55 μs (g55),and 490 μs (g490),as well as 2 modified pulse distances (g33d,g40d). measurements of temperature change were performed at the surface (thermal camera/50 hz),at the underside (thermocouples),and at the pulp chamber using a thermobath and human molars (n = 10). in addition,histology and x-ray diffraction (xrd/n = 10) were performed. erosion was tested using an erosive cycling over 6 d,including immersion in citric acid (2 min/0.05 m/ph = 2.3) 6 times daily. surface loss was measured using a profilometer and statistical analysis with a 2-way repeated-measures analysis of variance (α = 0.05). only g20 fulfilled the temperature requirements at the surface (619 ± 21.8°c),at the underside (5.3 ± 1.4°c),and at the pulp (2.0 ± 1.0°c),and it caused no mineral phase change and significant reduction of enamel surface loss (-13.2 ± 4.0 μm) compared to c (-37.0 ± 10.1 μm,p < 0.05). a laser-scanning strategy (20 μs/2 khz/1.25 j/cm2,3.4 mm/s) has been established that fulfilled the criteria for biological safety and significantly increased enamel erosion resistance (64%) in vitro. © international & american associations for dental research.