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

Abstract

The aim of this study was to assess the effectiveness of dual wavelength (2780 nm Er,Cr:YSGG, 940 nm diode) laser in elimination of smear layer comparing it with Er,Cr:YSGG laser in terms of radicular dentin permeability and ultrastructural changes of root canal walls. Fifty-one sound single-rooted extracted teeth were instrumented up to size F4 and divided into three groups: group Co, non-irradiated samples; group A, irradiated with Er,Cr:YSGG laser; group B, irradiated with the dual wavelength laser. Afterward, the roots were made externally impermeable, filled with 2% methylene blue dye, divided horizontally into three segments reflecting the cervical, middle, and apical thirds then examined under microscope. Using analytical software, the root section area and dye penetration area were measured, and then, the percentage of net dye penetration area was calculated. Additionally, scanning electron microscope investigations were accomplished. Analysis of variance (ANOVA) showed significant differences between all groups over the three root thirds. Dye permeation in dual wavelength laser group was significantly higher over the whole root length: cervical, middle, and apical compared to Er,Cr:YSGG laser group and non-irradiated samples (p < 0.001). Scanning electron micrographs of dual wavelength irradiated samples showed a distinctive removal of smear layer with preservation of the annular structure of dentinal tubules. Er,Cr:YSGG laser root canal irradiation produced uneven removal of smear layer, in efficient cleanliness especially in the apical third. There was no sign of melting and carbonization. Within the studied parameters, root canal irradiation with dual wavelength laser increased dentin permeability.

The effect of bleaching gel and (940 nm and 980 nm) diode lasers photoactivation on intrapulpal temperature and teeth whitening efficiency

“…This may be as a result of the selective absorption of the laser light by the gel, then photothermally, accelerating hydrogen peroxide dissociation by heating up the bleaching gel, thus decreasing heat transmission to the tooth. Otherwise, in the absence of bleaching gel scattering domains over absorption and a direct transmission of the laser energy to the thermocouple occurs .…”

Temperature elevation during root canal treatment with a 445-nm diode laser—an in vitro study

“…Each root was put into a mold that had been filled with polyurethane resin material mixed in a ratio of 5:1 (ISO-PUR K 760; Elze, Germany); the hardening process of polyurethane resin changed at regular intervals, and it took 40 to 45 min to harden completely. This casting resin was chosen for its thermal conductivity of 0.6 W/Km which is similar to that of cortical bone (0.58 W/Km) [23,30]. Before the resin hardened, the access holes to the root canal and to the drilled holes on both sides of the root canal were exposed.…”

“…Unlike the conventional method, lasers of suitable wavelengths have an excellent capacity for bacterial reduction at elimination depths exceeding 1000 μm in deep dentin tubules [13,21,22]. However, despite the potential benefits of lasers, too high, a dose of the absorbed energy may cause thermal damage to periodontal ligaments and lad to bone necrosis [15,23,24]. To achieve favorable outcomes and avoid thermal damage to the surrounding tissue, safe parameters must be identified [25,26].…”

Influência de diferentes protocolos de irrigação nas paredes do canal radicular em relação à retenção das restaurações de resina composta utilizadas como reforço de raízes fragilizadas

“…A introdução de compósitos fotopolimerizáveis tem sido defendida para reforçar raízes debilitadas (GODDER et al, 1994;LUI, 1994;MARTINS, 1995;SAUPE et al, 1996;OLIVEIRA Jr., 1997;TJAN et al, 1997;DE PAULA et al, 1998;MIRANZI et al, 2001;COELHO, 2003;HOU et al, 2003;MARCHI et al, 2003;ARUNPRADITKUL et al, 2004;SUMPANSIRIKUL et al, 2004;Al-KARADAGHI et al, 2015;BORZANGY et al, 2017) entretanto, algumas dificuldades se interpõem em decorrência de situações adversas que tende minimizar o sucesso almejado. A permeabilidade dentinária na região que receberá o reforço é bastante desfavorável em detrimento da situação anatômica que se apresenta, e seria uma causa relevante a se considerar.…”

“…A permeabilidade dentinária na região que receberá o reforço é bastante desfavorável em detrimento da situação anatômica que se apresenta, e seria uma causa relevante a se considerar. As implicações clínicas desse fato se devem a perda da dentina radicular interna, tanto mecanicamente pelo profissional como por processos patológicos, e o remanescente torna-se menos permeável por apresentar canalículos com menor diâmetro e menor número (GARBEROGLIO; BRÄNNSTRÖN, 1976;KARADAGHI et al, 2015;BORZANGY et al, 2017), e a aderência do material proposto para o reforço estaria comprometida. Estes fatos são fortes indícios da necessidade em buscar meios que promovam melhor união da resina composta à dentina remanescente, consequentemente maior retenção da restauração radicular.…”