Evaluating the effect of poly (amidoamine) treated bioactive glass nanoparticle incorporated in universal adhesive on bonding to artificially induced caries affected dentin.

BACKGROUND: The purpose of this study was to evaluate remineralisation and its effect on microtensile bond-strength of artificially induced caries affected dentin (CAD) when treated with a commercial universal adhesive modified with poly(amidoamine) dendrimer (PAMAM) loaded mesoporous bioactive glass nanoparticles (A-PMBG). MATERIAL AND METHODS: Mesoporous bioactive glass nanoparticles (MBG) were synthesised using sol-gel process, where PAMAM was loaded (P-MBG) and added to commercial adhesive at different weight percentages (0.2, 0.5, 1 and 2 wt%). First, rheological properties of commercial and modified adhesives were evaluated. The effect of remineralization/hardness and microtensile bond-strength (MTBs) of those samples that mimicked the rheological properties of commercial adhesives were evaluated using Vickers hardness tester and universal testing machine respectively. Scanning-Electron microscope was used to visualize failed samples of MTBs and remineralization samples. Both evaluations were carried out at 1-,3 and 6-month intervals, samples being stored in stimulated salivary fluid during each time interval. RESULTS: Addition of nanoparticles altered the rheological properties. With increase in the weight percentage of nanoparticles in commercial adhesive, there was significant increase in degree of conversion, viscosity and sedimentation rate (p < 0.05). The 0.2 and 0.5 wgt% groups closely mimicked the properties of commercial adhesive and were evaluated for remineralization and MTBs. After 6 months, 0.2wgt% group showed increased MTBs (p < 0.05) and 0.5wgt% group increased remineralization/hardness (p < 0.05). CONCLUSION: The complex of PAMAM-MBG-Universal adhesive can remineralize the demineralised CAD thereby improving its bond-strength when evaluated for up to 6-months.

Comparative evaluation of shear bond strength of zirconia restorations cleansed various cleansing protocols bonded with two different resin cements: An In vitro study.

CONTEXT: Yttria partially stabilized tetragonal zirconia polycrystalline restorations have gained widespread use because of its enhanced strength and esthetics. During the try-in process, zirconia is likely to be contaminated with saliva. This contamination leads to a clear weakening of the bond between restorative material and cement. For this reason, zirconia surface should be cleaned before cementation. Hence, the purpose of this study is to compare the shear bond strength of zirconia restorations cleansed with various surface cleansing protocols bonded with two different resin cements. MATERIALS AND METHODS: Eighty samples of zirconia discs were prepared in the dimensions 2.5 mm diameter and 4.5 mm thickness. They were divided into two groups of each forty samples based on luting cement used. Each group was further subdivided into four subgroups of each (n = 10): Group 1: uncontaminated zirconia blocks, Group 2: saliva-contaminated zirconia blocks and cleaned only with distilled water, Group 3: saliva-contaminated zirconia blocks treated with Ivoclean, and Group 4: saliva-contaminated zirconia blocks were air abraded. Eighty human maxillary premolars were then sectioned to expose dentin and were mounted on an acrylic block. A jig was fabricated to bond zirconia with the tooth using two self-adhesive resin cements. The samples were subjected to shear bond strength testing. The data were analyzed using one-way analysis of variance and Tukey's honest significance difference test with a level of significance set at p < 0.05. RESULTS: The mean shear bond strength values of Group 1 and 2 - subgroup B are 10.3 ± 0.4 and 9.80 ± 0.7 (saliva-contaminated zirconia, cleansed with distilled water only), respectively, were lowest among all test subgroups and were significantly less than mean values of subgroup C, Group 1 - 20.45 ± 0.6 and Group 2 - 20.75 ± 0.4 (Ivoclean group) and subgroup D, Group 1 - 20.90 ± 0.3 and Group 2 - 20.60 ± 0.5 (air abrasion group) (p < 0.05) for both test groups. CONCLUSIONS: In a clinical practice, a simple application of Ivoclean can be an effective alternative to air abrasion in removing salivary contaminants and improve resin-zirconia bonding.