Apical microleakage and SEM analysis of dentin surface after 980 nm diode laser irradiation

Abstract

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.

Evaluation of chemical and morphological changes in radicular dentin after different final surface treatments

“…The analysis of the morphological alterations after 980 nm diode laser irradiation showed a prevalence of a laser-modified smear layer and exposed dentinal tubules, which most resembled the group treated with NaOCl and EDTA without irradiation, resulting in less intense changes compared to the other lasers. These results are consistent with previous studies (Alfredo et al, 2009;Faria et al, 2011;Marchesan et al, 2008).…”

“…Each type of laser has its specificity and interacts differently with the hard dental tissues (Esteves‐Oliveira et al, ; Faria et al, ; Lopes et al, ; Saydjari et al, ). Also, the ultrastructural features and chemical changes of dentin depend mainly on the laser parameters such as output power, frequency and application mode, because these parameters are directly related to the increase in temperature (Alfredo, Marchesan, Sousa‐Neto, Brugnera‐Junior, & Silva‐Sousa, ; Beer et al, ; Faria, Souza‐Gabriel, Alfredo, Messias, & Silva‐Sousa, ; Lopes et al, ). Accordingly, previous studies have evaluated the thermal, morphological, and chemical effects in dentin irradiated with high power lasers, to determine parameters for a safe clinical application (Abad‐Gallegos, Arnabat‐Dominguez, Espana‐Tost, Berini‐Aytes, & Gay‐Escoda, ; Alfredo et al, ; Beer et al, ; Lopes et al, ; Marchesan, Brugnera‐Junior, Souza‐Gabriel, Correa‐Silva, & Sousa‐Neto, ; Yamazaki, Goya, Yu, Kimura, & Matsumoto, ).…”

Investigations of radicular dentin permeability and ultrastructural changes after irradiation with Er,Cr:YSGG laser and dual wavelength (2780 and 940 nm) laser

“…These findings were mainly resulted from combining a chemical irrigant like EDTA or NaOCl with diode laser, taking into account when water was set as an irrigant solution with diode laser (similar to our study) dye penetration that was much lower [27][28][29].…”

Comparative SEM Study on the Effect of Irrigating the Radicular Dentine with NaOCl and EDTA Through Conventional Techniques and Diode Laser

“…The choice for the two power settings (1.5 and 3W), as well as the 100 Hz frequency was based on the results presented by Alfredo et al who proved that these parameters resulted in a temperature increase of approximately 10 ° C, a value that is not above the threshold beyond which thermal damage may appear at the periapical thermal layer level [17,18].…”