PubMed · 3075216
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B D Hoffman. 1988. Indirect bonding with a diagnostic setup.. https://pubmed.ncbi.nlm.nih.gov/3075216/
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BACKGROUND AND OBJECTIVES: Previous studies have shown that during the laser irradiation of dentin and bone, thermal damage can be minimized by using a highly absorbed laser wavelength, laser pulses shorter than the thermal relaxation time of the deposited laser energy at that wavelength, and the addition of a layer of water to the tissue surface before ablation. The objective of this study was to investigate the influence of laser pulse duration and wavelength with and without the added water layer on the bond strength of composite to laser prepared dentin surfaces. The specific hypothesis that was tested was that thermal damage to the collagen matrix in dentin compromises the bond strength to composite restorative materials. STUDY DESIGN/MATERIALS AND METHODS: Three laser systems were employed that were tuned to water, collagen, and mineral absorption with pulse durations less than the thermal relaxation time of the deposited energy. The surfaces of human dentin were irradiated by laser irradiation from free-running and Q-switched Er:YSGG lasers, pulsed CO(2) lasers operating at 9.6-microm, and a Q-switched Nd:YAG laser operating at 355-nm. A motion control system and a pressurized spray system incorporating a microprocessor controlled pulsed nozzle for water delivery, were used to ensure uniform treatment of the entire surface. Shear bond testing was used to evaluate the adhesive strength in order to access the suitability of laser treated surfaces for bonding. Bonded interfaces were examined by SEM. RESULTS: All the laser groups had significantly lower bond strengths than the positive acid etch control group. The highest bond strengths were for the short pulse (< 5-microsecond) Er:YSGG and CO(2) laser groups with water. Laser groups without water had significantly reduced bond strengths and thicker layers of thermally damaged dentin. CONCLUSIONS: Thermal damage to the collagen matrix profoundly influences the bond strength to composite restorations.
The aim of this study was to investigate differences between plasma and halogen light polymerization in relation to the attainable shear bond strength of brackets bonded with various adhesives. 720 brackets were divided into 72 different groups of n = 10. The brackets were bonded to 240 flat polished test specimens produced from bovine teeth, Pontor MPF alloy, and extra hard plaster (type III) respectively. Transbond XT, Kurasper F or Fuji Ortho LC served as adhesives to bond either ceramic (Transcend 6000) or stainless steel brackets (Mini Uni-Twin). 50% of all brackets were bonded with a minimum layer of adhesive, and the remaining 50% with an adhesive layer thickness of 1.0 mm. In 360 cases the adhesive was polymerized with a plasma light (PAC), and in a further 360 cases with a halogen light (Optilux 401). The light curing time was 10 s with plasma light and 40 s with halogen light. After 24 h of storage in deionized water at room temperature, all brackets were subjected to a shear bond strength test according to ISO standard 10477. The measured shear bond strength did not differ significantly between the two curing light sources. The 1 mm adhesive layer thickness group showed significantly higher shear bond strengths in comparison to the minimum layer thickness group.
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