Abstract
BackgroundTo investigate the effects of Er:YAG laser pre-treatment on the dentin structure and shear bond strength of primary teeth.MethodsDentin specimens were prepared using freshly extracted intact primary molars and divided randomly into four groups based on the surface treatment applied. The control and etchant groups received no treatment and conventional acid etching treatment, respectively, while the energy and frequency groups received laser surface treatment with variable energy (50–300 mJ) and frequency (5–30 Hz) parameters. The morphology was observed using scanning electron microscopy. The surface-treated dentin slices were bonded to resin tablets, followed by thermocycle treatment. The shear strength was determined using a universal testing machine and de-bonded surfaces were observed using a stereomicroscope.ResultsSEM observation showed that the surface morphology of the dentin slices changed after etching as well as after Er:YAG laser pre-treatment with different energy and frequency values. The dentin tubules opened within a specific energy (50–200 mJ) and frequency (5–20 Hz) range. Beyond this range, the intertubular dentin showed cracks and structural disintegration. Shear strength tests showed no significant changes after acid etching. The shear strength increased significantly (P < 0.05) after Er:YAG laser pre-treatment compared with that of the control group. The shear strength increased within the same energy (50–200 mJ) and frequency (5–20 Hz) range as the tubule opening, but not significantly (P > 0.05). The most common mode of interface failure was adhesive (interface) failure, followed by mixed and resin cohesive failure.ConclusionsPre-treatment using Er:YAG laser opens the dentinal tubules without the formation of a smear layer and improves the bonding strength between the primary teeth dentin and the resin composites.
Highlights
To investigate the effects of erbium-doped yttrium aluminum garnet (Er):YAG laser pre-treatment on the dentin structure and shear bond strength of primary teeth
Scanning electron microscope (SEM) analysis In order to observe the effects of various treatments on the dentin surface, two dentin specimens were randomly selected from each group and analyzed with SEM (s-4800 Hitachi, Japan)
Shear bond strength testing The shear strength of the specimens were determined using a universal testing machine (AGS 500, Shimadzu, Morphology of dentin surface following laser treatments at a specific frequency (10 Hz) and variable energy levels In the control group, the dentin surface covered with thick smear layer, dentin tubule openings were blocked, and the boundary between the peritubular dentin and intertubular dentin was unclear (Fig. 2a)
Summary
To investigate the effects of Er:YAG laser pre-treatment on the dentin structure and shear bond strength of primary teeth. The Nd:YAG laser operates at a wavelength of 1064 nm, which is appropriate for intermittent laser emission with minimal heat accumulation and the prevention of excessive temperature increase. These characteristics of the Nd:YAG laser result in superior efficacy and a lower possibility of damaging adjacent tissues [4]. The Er:YAG laser causes no pain or discomfort unlike traditional air turbine hand-held devices, making it especially suitable for the treatment of primary teeth in pedodontic patients. The effects of conventional treatment and Er:YAG laser pre-treatment on the dentin structure of primary teeth and the shear bond strength (SBS) to resin composite were investigated. This study provides an experimental and theoretical basis for encouraging the application of Er:YAG laser pre-treatment during clinical treatment of primary teeth among pediatric patients
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