Progression of dental erosion after Nd:YAG laser irradiation

Abstract

In order to evaluate, by optical profilometry, the progression of toothware after treatment with Nd:YAG laser irradiation and fluoride, 120 single-rooted bovine teeth will be used after prophylaxis. Roots will be removed from the crowns with the aid of double blade disc at low speed. The teeth will be positioned in a metallographic machine to obtain samples from dentin (4x4x2 mm). The samples will be embedded in acrylic resin and polished with abrasive paper and felt disc with diamond paste. Then, the specimens will be subjected to an ultrasound bath for 3 minutes. After that the polished surfaces will receive a tape of UPVC, which will leave an exposed window center 4x1mm. To induce acid erosion in vitro, the samples will be inserted two times daily for 5 days in 80 ml of 0.05m citric acid (citric acid monohydrate - C6H8O7. H2O), M = 210.14 g / mol) pH 2.3 at room temperature for 20 minutes. After this period, it is believed the formation of an erosion damage. Thus there will be the second reading by perfilometry (Per-2). With the lesions, the samples will be then separated into eight groups (n = 15): G1. control (untreated), G2: acidulated phosphate fluoride (F), G3: Nd:YAG (Power LaserTM ST6, Lares Research) - contact mode, pulsed, focused, perpendicular, fiber 400 m m (L) (Protocol 1: 0.5 W/10Hz, 10s, 50J, 41.66 J/cm2), G4: Nd: YAG (protocol 2: 0.75 W/10Hz, 10s, 75J, 62.50 J/cm2), G5: Nd:YAG (protocol 3: 1W/10Hz, 10 s, 50J, 83.33 J/cm2), G6 (F) + L1, G7 (F) + L2, G8: (F) + L3. After the treatments, the groups will be subjected to new acid challenges, so that the samples will be evaluated at the 3rd and 5th. challenges (Per-Per-3 and 4, respectively). After cycling, the tape will be removed and the surface test will be analyzed with an optical profilometer (Proscan 2100, Scantron) to determine the loss of surface. The values obtained will be statistically analyzed to determine the homogeneity and normality of the sample. From this analysis it will be choosen the most appropriate statistical test for comparison between the experimental groups performed. (AU)