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.