Influence of Er:YAG laser surface treatment on flexural and bond strengths to glass-infiltrated zirconia-reinforced ceramic.

To evaluate the effect of Er:YAG laser conditioning of a glass-infiltrated alumina-based zirconia-reinforced ceramic on its flexural strength and on bonding to a resin cement. Sixteen blocks (5 × 5 × 4 mm) and 50 discs (Ø 12 mm, 1 mm thickness) of In-Ceram Zirconia (ICZ) obtained from CAD-CAM blocks were infiltrated with glass. For the microtensile bond strength (µTBS) test, all blocks were treated with aluminum oxide (AOX) and divided into 4 groups (n = 4): G1 (AOX), no combined surface treatment; G2 (ROC), tribochemical silica-coating; G3 (EY200), Er:YAG laser 200 mJ/15 Hz; and G4 (EY250), Er:YAG laser 250 mJ/10 Hz. The ceramic blocks were silanated and cemented with a resin cement (Panavia F2.0/Kuraray) to composite resin blocks and subjected to the µTBS test. For the flexural strength evaluation, the discs were divided into 5 groups (n = 10) as described above, in addition to a control group (G5 - CTRL, mirror-polished without further treatment). Each surface treatment was submitted to qualitative evaluation under SEM. One-way ANOVA (α = 5%) revealed the highest bond strength value for EY200 with no significant difference from ROC. The groups AOX and EY250 showed similar µTBS values that were statistically lower than those of EY200. For flexural strength, ROC was the only group with significantly lower values when compared with the CTRL. The use of Er:YAG laser at 200 mJ/15 Hz can be considered an innovative and effective alternative for surface conditioning of ICZ since it did not reduce the flexural strength of the ceramic and improved the resin cement bond to this substrate.

Microtensile bond strength analysis of adhesive systems to Er:YAG and Er,Cr:YSGG laser-treated dentin.

The aim of this in vitro study was to evaluate the effect of different surface treatments (control, diamond bur, erbium-doped yttrium aluminum garnet (Er:YAG) laser, and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser) on sound dentin surface morphology and on microtensile bond strength (µTBS). Sixteen dentin fragments were randomly divided into four groups (n = 4), and different surface treatments were analyzed by scanning electron microscopy. Ninety-six third molars were randomly divided into eight groups (n = 12) according to type of surface treatment and adhesive system: G1 = Control + Clearfil SE Bond (SE); G2 = Control + Single Bond (SB); G3 = diamond bur (DB) + SE; G4 = DB + SB, G5 = Er:YAG laser (2.94 µm, 60 mJ, 2 Hz, 0.12 W, 19.3 J/cm(2)) + SE; G6 = Er:YAG + SB, G7 = Er,Cr:YSGG laser (2.78 µm, 50 mJ, 30 Hz, 1.5 W, 4.5 J/cm(2)) + SE; and G8 = Er,Cr:YSGG + SB. Composite blocks were bonded to the samples, and after 24-h storage in distilled/deionized water (37 °C), stick-shaped samples were obtained and submitted to µTBS test. Bond strength values (in megapascal) were analyzed by two-way ANOVA and Tukey tests (α = 0.05). G1 (54.69 ± 7.8 MPa) showed the highest mean, which was statistically significantly higher than all the other groups (p < 0.05). For all treatments, SE showed higher bond strength than SB, except only for Er,Cr:YSGG treatment, in which the systems did not differ statistically from each other. Based on the irradiation parameters considered in this study, it can be concluded that Er:YAG and Er,Cr:YSGG irradiation presented lower values than the control group; however, their association with self-etching adhesive does not have a significantly negative effect on sound dentin (µTBS values of >20 MPa).

Microtensile bond strength of composite resin to glass-infiltrated alumina composite conditioned with Er,Cr:YSGG laser.

Tribochemical silica-coating is the recommended conditioning method for improving glass-infiltrated alumina composite adhesion to resin cement. High-intensity lasers have been considered as an alternative for this purpose. This study evaluated the morphological effects of Er,Cr:YSGG laser irradiation on aluminous ceramic, and verified the microtensile bond strength of composite resin to ceramic following silica coating or laser irradiation. In-Ceram Alumina ceramic blocks were polished, submitted to airborne particle abrasion (110 µm Al(2)O(3)), and conditioned with: (CG) tribochemical silica coating (110 µm SiO(2)) + silanization (control group); (L1-L10) Er,Cr:YSGG laser (2.78 µm, 20 Hz, 0.5 to 5.0 W) + silanization. Composite resin blocks were cemented to the ceramic blocks with resin cement. These sets were stored in 37°C distilled water (24 h), embedded in acrylic resin, and sectioned to produce bar specimens that were submitted to microtensile testing. Bond strength values (MPa) were statistically analyzed (α ≤0.05), and failure modes were determined. Additional ceramic blocks were conditioned for qualitative analysis of the topography under SEM. There were no significant differences among silicatization and laser treatments (p > 0.05). Microtensile bond strength ranged from 19.2 to 27.9 MPa, and coefficients of variation ranged from 30 to 55%. Mixed failure of adhesive interface was predominant in all groups (75-96%). No chromatic alteration, cracks or melting were observed after laser irradiation with all parameters tested. Surface conditioning of glass-infiltrated alumina composite with Er,Cr:YSGG laser should be considered an innovative alternative for promoting adhesion of ceramics to resin cement, since it resulted in similar bond strength values compared to the tribochemical treatment.

Benefícios dos lasers de alta e baixa potência no procedimento restaurador direto: relato de caso / Benefits of low and high power lasers on direct restorative procedures: a case report

Lasers de alta e baixa potência têm sido amplamente utilizados em diversas especialidadesda Odontologia. Na Dentística, podem ser utilizados em diferentes etapas do procedimento restaurador direto, como na remoção seletiva do tecido cariado e redução de sensibilidade pós¬preparo cavitário. Este artigo tem como objetivo apresentar um relato de caso em que diferentes lasers foram utilizados e discutir, baseado em resultados de estudos já publicados na literatura, os benefícios de cada um deles quando associados ao procedimento convencional.

High and low power lasers have been widely used in different specialties of Dentistry. InRestorative Dentistry, it can be used in different steps of the direct restorative procedure, as for the selectively remova I of caries tissue and for the reduction of tooth sensitivity following cavity preparation. This article aims to present a case report in which different lasers were used and discuss, based on results of studies already published in the literature, the benefits of each laser when associated with conventional procedures.

Influence of intrapulpal pressure simulation on the bond strength of adhesive systems to dentin.

The purpose of this study was to evaluate the influence of intrapulpal pressure simulation on the bonding effectiveness of etch & rinse and self-etch adhesives to dentin. Eighty sound human molars were distributed into eight groups, according to the permeability level of each sample, measured by an apparatus to assess hydraulic conductance (Lp). Thus, a similar mean permeability was achieved in each group. Three etch & rinse adhesives (Prime & Bond NT - PB, Single Bond -SB, and Excite--EX) and one self-etch system (Clearfil SE Bond--SE) were employed, varying the presence or absence of an intrapulpal pressure (IPP) simulation of 15 cmH2O. After adhesive and restorative procedures were carried out, the samples were stored in distilled water for 24 hours at 37 degrees C, and taken for tensile bond strength (TBS) testing. Fracture analysis was performed using a light microscope at 40 X magnification. The data, obtained in MPa, were then submitted to the Kruskal-Wallis test ( a = 0.05). The results revealed that the TBS of SB and EX was significantly reduced under IPP simulation, differing from the TBS of PB and SE. Moreover, SE obtained the highest bond strength values in the presence of IPP. It could be concluded that IPP simulation can influence the bond strength of certain adhesive systems to dentin and should be considered when in vitro studies are conducted.

Avaliação do contorno gengival na estética do sorriso / Evaluation of gingival contour in the aesthetic of the smile

Introdução - A definição de parâmetros e padrões estéticos em Odontologia, bem como a satisfação do paciente frente a um tratamento estético vem sendo bastante discutido atualmente por cirurgiões-dentistas de diferentes áreas. O objetivo deste trabalho foi avaliar a influência do contorno gengival na percepção estética de cirurgiões-dentistas e pacientes. Material e Métodos - Dois grupos formados por 30 cirurgiões-dentistas e 30 pacientes avaliaram 6 figuras com diferentes contornos gengivais de modo a se determinar os contornos mais agradáveis para cada grupo.Os resultados foram avaliados estatisticamente pelo teste Mann-Whitney e Kruskal-Wallis. Resultados - Não houve diferença estatisticamente significante entre os grupos quanto à escolha dos sorrisos mais agradáveis para todas as figuras, com exceção da Figura 3. As Figuras 3, 5 e 7 foram avaliadas positivamente e as Figuras 4, 6 e 8 não foram aceitas por ambos os grupos. Conclusão - Os dois grupos estudados têm escolhas semelhantes quanto à maioria dos contornos gengivais.Os sorrisos mais harmônicos transmitem uma sensação mais agradável aos observadores.

Introduction - The definition of aesthetics guidelines and standards in Dentistry, as well the patient's satisfaction with the aesthetic outcome is a subject that has been discussed between dentists from different areas. The aim of this study was to evaluate the influence of gingival contour in the aesthetic perception of dentists and patients. Material and Methods - Six photos with different gingival contours were classified by 2 experimental groups, dentists and patients to determine the most pleasant contours for each group. The results were submitted to Mann-Whitney and Kruskal-Wallis statistical analysis. Results - There was no statistically significant difference between the groups in the choices for the more pleasant smile, except by the Figure 3. Figures 3, 5 and 7 were positively evaluated. Figures 4, 6 and 8 weren't accepted as pleasant by both groups. Conclusion - Both dentists and patients had similar views of the most gingival contours. The harmonic smiles transmitted a pleasant sensation to the observers.

Influence of intrapulpal pressure simulation on the bond strength of adhesive systems to dentin

The purpose of this study was to evaluate the influence of intrapulpal pressure simulation on the bonding effectiveness of etch & rinse and self-etch adhesives to dentin. Eighty sound human molars were distributed into eight groups, according to the permeability level of each sample, measured by an apparatus to assess hydraulic conductance (Lp). Thus, a similar mean permeability was achieved in each group. Three etch & rinse adhesives (Prime & Bond NT - PB, Single Bond -SB, and Excite - EX) and one self-etch system (Clearfil SE Bond - SE) were employed, varying the presence or absence of an intrapulpal pressure (IPP) simulation of 15 cmH2O. After adhesive and restorative procedures were carried out, the samples were stored in distilled water for 24 hours at 37°C, and taken for tensile bond strength (TBS) testing. Fracture analysis was performed using a light microscope at 40 X magnification. The data, obtained in MPa, were then submitted to the Kruskal-Wallis test ( a = 0.05). The results revealed that the TBS of SB and EX was significantly reduced under IPP simulation, differing from the TBS of PB and SE. Moreover, SE obtained the highest bond strength values in the presence of IPP. It could be concluded that IPP simulation can influence the bond strength of certain adhesive systems to dentin and should be considered when in vitro studies are conducted.