Mechanical properties of the bond interface associated with nd:yag laser

Abstract

<p class="western" lang="en-US"><span style="font-family: Arial, sans-serif;"><strong>ABSTRACT</strong></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"><strong>Objective</strong></span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">:This study evaluated the </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">hardness and modulus of elasticity</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">of the </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">dentin </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">bond interface</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"> using total-etch (Single Bond /SB) and self-etch (Clearfil SE Bond/CSEB) adhesives associated with Nd:YAG Laser irradiation through the unpolymerized adhesives.</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"><strong>Material and Methods</strong></span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">: The occlusal surfaces of 12 human third molars were ground until superficial dentin was exposed. A standardized circular cavity was performed on the occlusal surface. Specimens were sectioned in the mesio-distal direction, and the 24 hemi-crowns were divided into four groups: Group SB/Control - SB + polymerization; Group SB/Laser - SB</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"><em> +</em></span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"> Nd:YAG laser (</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">174.16J/cm</span></span></span><span style="color: #000000;"><sup><span style="font-family: Arial, sans-serif;"><span lang="en-US">2</span></span></sup></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">/60s/non-contact) + polymerization; Group </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">CSEB/</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">Control – </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">CSEB + </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">polymerization; Group </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">CSEB</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">/Laser - </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">CSEB + </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">Nd:YAG laser (</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">174.16J/cm</span></span></span><span style="color: #000000;"><sup><span style="font-family: Arial, sans-serif;"><span lang="en-US">2</span></span></sup></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">/cm</span></span></span><span style="color: #000000;"><sup><span style="font-family: Arial, sans-serif;"><span lang="en-US">2</span></span></sup></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">/60s/non-contact) + polymerization. </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">Composite </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">were placed in the cavities and polymerized. The specimens were immersed in distilled water and stored in an oven at 37ºC for 24h and then submitted to nanoindentation in a Nano Indenter® XP appliance. </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"><strong>Results</strong></span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">: The results were submitted to ANOVA, Tukey’s test and Student's-</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"><em>t</em></span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"> test (p < 0.05). </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"><strong>Conclusão: </strong></span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">It was concluded that the application of the Nd:YAG laser in both adhesive systems did not changed the hybrid layer hardness; however, it increases the modulus of elasticity </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en">in the hybrid layer </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US">for both adhesives tested and it maybe preserves the integrity of the adhesive interface and its durability.</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"><strong> Clinical relevance:</strong></span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"> The application of Nd:YAG laser prior to photopolymerization of adhesive systems can increase the modulus of elasticity </span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en">in the hybrid layer and</span></span></span><span style="color: #000000;"><span style="font-family: Arial, sans-serif;"><span lang="en-US"> may contribute to stress distribution in the adhesive interface during the polymerization preserving the integrity of the adhesive interface and its durability.</span></span></span></p>

Effect of Diode Laser Irradiation of Bonding Agents Before Curing Versus Standard Bonding Protocol on the Shear Bond Strength Between Resin Cement and Dentin

“…In addition, the presence of MDP and NaF in the Clearfil Liner Bond F may have contributed to the increased bond strength. Barcellos et al [27] found laser irradiation to increase the modulus of elasticity of the formed hybrid layer, causing less polymerization shrinkage stresses at the interface. This may explain the intact hybrid layer seen in group TS-L.…”

“…The authors theorized that the heat energy from the laser formed a new substrate in which the hydroxyapatite has been melted and fused in the presence of bond monomers. [23] The use of laser energy on the bonding agent before its curing has since been evaluated in further studies and has been further hypothesized to increase bond penetration [24], help evaporate the solvent [25], increase its degree of conversion (DC) [26], and increase the modulus of elasticity of the hybrid layer [27]. All supposedly through the photothermal effect of the laser on the adhesive.…”