Effect of Er:YAG laser and diamond drill on hybrid layer morphology obtained with self-etch adhesive: analysis by SEM and confocal laser scanning microscopy (CLSM)

This study aimed to evaluate the effect of Er:YAG (L) and diamond drills (DD) on: 1) the microshear bond strength (MPa); 2) the adhesive interface of two-step (TS) – Adper Scotchbond Multipurpose and one-step (OS) adhesives – Adper EasyOne, both from 3M ESPE. Material and methods: According to the preparation condition and adhesives, the samples were divided into four groups: DD_TS (control); DD_OS; L_TS and L_OS. 60 bovine incisors were randomly divided into experimental and groups: 40 for microshear bond strength (n = 10) and 20 for the adhesive interface morphology [6 to measure the thickness of the hybrid layer (HL) and length of tags (t) by CLSM (n = 3); 12 to the adhesive interface morphology by SEM (n = 3) and 2 to illustrate the effect of the instruments on dentine by SEM (n = 1)]. To conduct the microshear bond strength test, four cylinders (0.7 mm in diameter and 1 mm in height with area of adhesion of 0.38 mm) were constructed with resin composite (Filtek Z350 XT – 3M ESPE) on each dentin surface treated by either L or DD and after adhesives application. Microshear bond strength was performed in universal testing machine (EMIC 2000) with load cell of 500 kgf and a crosshead speed of 0.5 mm / min. Adhesive interface was characterized by thickness of hybrid layer (HL) and length of tags (t) in nm, with the aid of UTHSCSA ImageTool software. Results: Microshear bond strength values were: L_TS 34.10 ± 19.07, DD_TS 24.26 ± 9.35, L_OS 33.18 ± 12.46, DD_OS 21.24 ± 13.96. Two-way ANOVA resulted in statistically significant differences only for instruments (p = 0.047). Mann-Whitney identified the instruments which determined significant differences for HL thickness and tag length (t). Concerning to the adhesive types, these differences were only observed for (t). Conclusion: It can be concluded that 1) laser Er:YAG results in higher microshear bond strength values regardless of the adhesive system (TS and OS); 2) the tags did not significant affect the microshear bond strength; 3) the adhesive interface was affected by both the instruments for cavity preparation and the type of adhesive system used.

The effect of final irrigation on the penetrability of an epoxy resin-based sealer into dentinal tubules: a confocal microscopy study

Introduction The aim of this study was to compare the effect of QMix, BioPure MTAD, 17 % EDTA, and saline on the penetrability of a resin-based sealer into dentinal tubules using a confocal laser scanning microscope (CLSM) and to describe the cleaning of root canal walls by SEM. Methods Eighty distobuccal roots from upper molars were selected and randomly divided into four groups (n=20) before root canal preparation according to the solution used in the final rinse protocol (FRP): QG (QMix), MG (BioPure MTAD), EG (17 % EDTA), and CG (control group: saline). Ten roots of each group were prepared for SEM, and images (×2000) from the canal walls were acquired. The remaining canals were filled with a single gutta-percha cone and AH Plus with 0.1 % Rhodamine B. The specimens were horizontally sectioned at 4 mm from the apex, and the slices were analyzed in CLSM (×10). Sealer penetration was analyzed with Adobe Photoshop software. Results QG and EG presented similar amounts of sealer penetration (P>.05). MG and CG presented the lowest penetrability values (P<.05). The best results for smear layer removal of the apical third of the root canal were achieved by the QG and EG groups when compared with MG and CG (P<.05). Conclusions Seventeen percent EDTA and QMix promoted sealer penetration superior to that achieved by BioPure MTAD and saline. Clinical relevance Despite studies have not confirmed the relationship between sealing ability of endodontic sealers and their penetration in dentinal tubules, sealer penetration assumes importance, since endodontic sealers, unlike guttapercha, are able to penetrate in dentinal tubules, isthmus, and accessory canals, filling the root canal system.

Elucidating the real-time Ag nanoparticle growth on alpha-Ag2WO4 during electron beam irradiation: experimental evidence and theoretical insights

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A combined experimental and theoretical study on the formation of ag filaments on beta-Ag2MoO4 induced by electron irradiation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Correlative light-electron fractography of interlaminar fracture in a carbon-epoxy composite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)