Microhardness of Radicular Dentin Treated with 980-nm Diode Laser and Different Irrigant Solutions

Abstract

Objective: The aim of this study was to evaluate the microhardness of radicular dentin after treatment with 980-nm diode laser and different irrigant solutions. Background data: There are few reports of the consequences of diode laser irradiation emitted at 980 nm on the mechanical properties of dentin. Methods: Seventy-two single canal, human canines with complete root formation were randomly distributed among three groups (n = 24), according to the irrigant solution used in the biomechanical preparation: distilled water; 1% NaOCl; and, 1% NaOCl + 17% EDTA. These groups subsequently were divided into three subgroups (n = 8), according to the diode laser parameter: no irradiation (control); 1.5 W/100 Hz; and 3.0 W/100 Hz. Laser was applied with helicoidal movements for 20 sec. Roots were sectioned in slices and the fragment corresponding to the middle third was submitted to the microhardness test (KHN) at depths of 30, 90, 150, and 300 lm. Results: ANOVA and Tukey tests showed that the microhardness of the groups irradiated with 1.5 W/100 Hz (49.7 -11.2) and 3.0 W/ 100 Hz (50.6 -11.9) were statistically similar to each other ( p > 0.05) and different ( p < 0.05) from the nonirradiated group (45.0 -9.7). Higher microhardness values were obtained at 150 lm (49.2 -11.0) and 300 lm (52.3 -11.3) which were similar among themselves and different ( p < 0.05) only at the depth of 30 lm (44.4 -10.5). No differences were found among the irrigant solutions ( p > 0.05). Conclusions: The microhardness of the radicular dentin increased after irradiation with 980-nm diode laser.

Impact of chemical agents for surface treatments on microhardness and flexural strength of root dentin

“…25 Additionally, the root resistance to fracture can be adversely affected by reduction in microhardness 26 and flexural strength. 21 The present study assessed the microhardness and flexural strength of root dentin exposed to chemical agents.…”

Effects of mechanical instrumentation and chemical irrigation on the root canal dentin and surrounding tissues

“…When root canals following preparation and irrigation with different irrigants (NaOCl, water, NaOCl/EDTA) were irradiated with a 980‐nm diode laser with 1 W/100 Hz, or 3 W/100 Hz, fracture resistance was not altered when compared to untreated controls . Following laser irradiation of root canals in extracted teeth with a 980‐nm diode laser with 1 W/100 Hz or 3 W/100 Hz for 20 s, the microhardness test (KHN) revealed increased microhardness when compared to non‐irradiated controls . Following irrigation with EDTA and the use of a 980‐nm diode laser, most of the dentin was free of a smear layer; open tubules and melted areas were detected .…”

Efeito da irradiação com lasers de alta potência na adesividade do cimento resinoso às paredes do interior do canal radicular e análise da interface adesiva

“…Os mais utilizados para essa finalidade são o carvão mineral/vegetal e o diaminofluoreto de prata a 12% (CALMON, 2001;JORDÃO, 2011). Como há a possibilidade da provocação de microfusões na superfície dentinária, foram adotados parâmetros seguros para minimizar esse risco, como a fixação da potência de 1.5 W e a frequência de 100 Hz, pulsátil (VIAPIANA et al, 2012;FARIA et al, 2012). Além desses parâmetros, a sinergia do tamanho e espessura adequados de fibra também foram fundamentais, e melhoraram a segurança e a utilização da técnica (JORDÃO, 2011).…”

“…No tratamento dos canais radiculares, os lasers são utilizados para a remoção do tecido pulpar residual e da camada de debris e smear (MICHIELS et al, 2010;MOURA et al, 2010;REDDY et al, 2013;SAHAR-HELFT et al, 2015), e na desinfecção do canal radicular por meio da redução significativa do número de bactérias (YASUDA et al, 2010;FRANZEN et al, 2011;PIRNAT et al, 2011;HSU et al, 2015). Porém, podem influenciar negativamente na dureza e permeabilidad e dentinária (MICHIELS et al, 2010;PIRNAT et al, 2011;MANEESHA et al, 2013;SAHAR-HELFT et al, 2015), visto que podem causar microfusões da superfície dentinária (HUIXIA et al, 2009;VIAPIANA et al, 2012). Essa possibilidade pode ser agravada pela elevação excessiva na temperatura durante a irradiação intracanal, mas é facilmente controlada mediante a utilização de parâmetros seguros (ALFREDO et al, 2008;HUIXIA et al, 2009;HMUD et al, 2010HMUD et al, , 2010a) e fibras adequadas para o procedimento em questão WALSH, 2011;MANEESHA et al, 2013).…”