The influence of erbium:yttrium–aluminum–garnet laser ablation with variable pulse width on morphology and microleakage of composite restorations

Abstract

The objective of this study was to evaluate the influence of various pulse widths with different energy parameters of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mum) on the morphology and microleakage of cavities restored with composite resin. Identically sized class V cavities were prepared on the buccal surfaces of 54 bovine teeth by high-speed drill (n = 6, control, group 1) and prepared by Er:YAG laser (Fidelis 320A, Fotona, Slovenia) with irradiation parameters of 350 mJ/ 4 Hz or 400 mJ/2 Hz and pulse width: group 2, very short pulse (VSP); group 3, short pulse (SP); group 4, long pulse (LP); group 5, very long pulse (VLP). All cavities were filled with composite resin (Z-250-3 M), stored at 37 degrees C in distilled water, polished after 24 h, and thermally stressed (700 cycles/5-55 degrees C). The teeth were impermeabilized, immersed in 50% silver nitrate solution for 8 h, sectioned longitudinally, and exposed to Photoflood light for 10 min to reveal the stain. The leakage was evaluated under stereomicroscope by three different examiners, in a double-blind fashion, and scored (0-3). The results were analyzed by Kruskal-Wallis test (P > 0.05) and showed that there was no significant differences between the groups tested. Under scanning electron microscopy (SEM) the morphology of the cavities prepared by laser showed irregular enamel margins and dentin internal walls, and a more conservative pattern than that of conventional cavities. The different power settings and pulse widths of Er:YAG laser in cavity preparation had no influence on microleakage of composite resin restorations.

Laser Technology for Caries Removal

“…In contrast, the use of high-speed drills for cavity preparation promotes enamel and dentin cavities flattened, with smooth internal walls and geometrically well-defined shapes, with closed dentinal tubules and presence of smear layer Navarro et al, 2010). These characteristics, as well as the changes in chemical and crystalline structure in remaining tissue promoted by laser irradiation, must be taken into consideration in order to choose an appropriate adhesive system for composite restoration, since the adhesive systems interact in a different way with laser or bur treated tissues (Moretto et al, 2011).…”

“…During cavity preparation, the ablation of sound enamel by Er:YAG laser promotes cavities with rough enamel margins, with irregular and rugged walls, with depth that depends on the energy density and pulse width (Navarro et al, 2010). As well, it is reported the absence of smear layer, cracks, carbonization or melting if the adequate parameters and refrigeration were used ).…”

In vitro microleakage of class v composite restorations prepared by Er,Cr:YSGG laser and carbide bur

“…Later, another laser of the erbium family, the Er,Cr:YSGG was also approved for the same application 1 . Despite the initial concerns about the safety of the laser irradiation, several studies showed that a laser is as safe as the conventional high-speed drills 13,14 . The erbium family of lasers can be used on dental hard tissues.…”

The Effect of Er:YAG Laser Irradiation and Different Concentrations of Sodium Hypochlorite on Shear Bond Strength of Composite to Primary Teeth’s Dentin

“…1 Among all types of lasers, Erbium-Doped Yttrium Aluminum Garnet laser (Er:YAG( is commonly used in dental hard tissues 2 and its ability for removing enamel and dentin is comparable to conventional methods. 1 Cavity preparation with Er:YAG laser has advantages such as removing dental hard tissues with minimal pulp injury, 3,4 creating a rough and irregular surface, 2 less side effects due to severe heat produced by conventional methods e.g.…”