PubMed · 283109
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N S Simmons. 1979. Enamel calcification.. https://doi.org/10.1177/002203457905800213011
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BACKGROUND AND OBJECTIVES: We have investigated the fundamental aspects of Nd:YAG laser at the picosecond pulse regime interacting with primary teeth. Because little is present in the literature concerning specific laser ablation for primary teeth with respect to enamel and dentin, this work may open perspectives for new investigations. STUDY DESIGN/MATERIALS AND METHODS: Using a picosecond Nd:YAG laser, different power levels (200, 300, and 350 mW) and different exposition times (5, 10, and 15 seconds) were considered. RESULTS: Micro-morphological aspects of the laser-tooth interaction showed collateral effects in enamel more accentuated than in dentin. Penetration depth in dentin seems to scale up in rate as the time of application progress, for enamel the behavior is the opposite. The overall ablated volume is higher in dentin when compared with enamel, which results in a higher ablated rate as well. CONCLUSIONS: Specific ablation characteristics are observed in either dentin or enamel.
This study evaluated by scanning electron microscopy (SEM) the morphological changes in occlusal fissure enamel, of permanent models, irradiated by Er:YAG laser using contact and noncontact fiberoptics in vitro. Previous studies have demonstrated the efficacy of Er:YAG laser for dental hard tissue removal and cavity preparation. The treatment of occlusal fissures in noncarious permanent human molars (n = 9) was carried out with Er:YAG laser (KEY Laser II) using handpiece no. 2051, noncontact, focused (12 mm), water spray-cooled, pulse energy 200 mJ, and frequency 2 Hz (group 1), and handpiece no. 2055 with a quartz fiberoptic 50/10, in contact, air cooled, pulse energy setting of 350 mJ and frequency 2 Hz (group 2) and 400 mJ/2 Hz (group 3). The specimens were sectioned, dehydrated in a graded series of aqueous ethanol, dried, and sputtering with gold. Morphological change analysis on occlusal fissures was performed by SEM. Group 1 showed removal of fissure debris and predominantly enamel etching-like patterns, and groups 2 and 3 showed irregular edges, melting, and recrystallization of fissure enamel, with a lava-like structure and bubble-like voids. The results of this in vitro study suggest that the irradiation of fissures by Er:YAG laser using a fiberoptics (contact and air cooled) produced melting and recrystallization of fissures enamel. Further studies are required with different energy parameters and water cooling to evaluate the thermal effects on teeth.
OBJECTIVE: The aim of this study was to assess the performance of three bonding agents in preventing microleakage of class V cavities prepared and treated by Er:YAG laser associating with acid etching. BACKGROUND DATA: There has been very little research comparing the efficiency of single-component and self-etching adhesive systems in preventing microleakage of cavities prepared and conditioned with Er:YAG laser. MATERIALS AND METHODS: Thirty cavities - with occlusal margin in enamel and cervical in dentin/cementum - were prepared in sound human third molars using a short pulsed Er:YAG laser (500 mJ/5 Hz) The enamel and dentin surfaces were conditioned for 30 sec using lower dosimetries (120 mJ/4 Hz), and the samples were randomly assigned into three groups, according to the adhesive system: (I) Bond-1; (II) Prime & Bond NT; and (III) Etch & Prime 3.0. Groups I and II were acid-etched for 15 sec, and group III did not receive any acid treatment once a self-etching system was employed. Cavities were restored with a light-cured composite resin (JEK-Z250 Filtek-250), and after finishing, the samples were thermocycled, isolated with epoxy resin and nail varnish, immersed in a 0.2% Rhodamine B solution for 24 h, and sectioned longitudinally. The sections obtained were analyzed for leakage using an optical microscope connected to a computer and a video camera. We digitized the images using a special software program that allowed a quantitative evaluation of microleakage in millimeters. RESULTS: Statistical analysis using the Kruskal-Wallis test showed statistically significant difference between both margins, and the occlusal region presented better marginal sealing. Comparing the three resin bonding systems, Prime & Bond NT entirely sealed both margins, while Etch & Prime 3.0 provided the poorest overall results, showing a statistically significant difference (p < 0.01). CONCLUSION: It may be concluded that, for all the tested materials, microleakage values were higher in cervical (dentin/cementum) margins. Additionally, Prime & Bond NT provided a complete elimination of marginal infiltration at both margins, after treating the dental surface with laser irradiation associated with a sequent acid-etching.