Durability of Resin Bonding to Zirconia Using Products Containing 10-Methacryloyloxydecyl Dihydrogen Phosphate

Purpose: To examine the durability of composite bonding to zirconia after artificial aging using different products containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Materials and Methods: Conditioning methods were: none (control [Ctr]; Clearfil SA Luting [CSL]; Panavia SA Luting Plus [PSLP]), MDP-containing zirconia primers (Z-Prime Plus [ZP]; Clearfil Ceramic Primer [CCP]), and MDP-containing universal adhesives (Single Bond Universal [SBU]; Clearfil Universal Bond [CUB]). For the Ctr, ZP, CCP, SBU, and CUB groups, the Y-TZP plates were bonded with MDP-free composite cement. For the remaining two groups, each Y-TZP plate was bonded with one of MDP-containing self-adhesive composite cements (CSL; PSLP). The specimens in each group (n = 30) were divided into two subgroups, with one subgroup of samples subjected to 24-h water storage and the other to aging through 30,000 thermocycles plus 180-day water storage. Shear bond strength (SBS) was measured. For each conditioning method, inductively coupled plasma-mass spectrometry (ICP-MS) was used to quantify the release of phosphorus, and microleakage was evaluated through a methylene-blue dyeing technique. Results: The Ctr group exhibited the lowest SBS regardless of aging. Thermocycling and water storage significantly decreased the SBS in all groups, with the exception of the groups with the MDP-containing zirconia primers. Groups with MDP-containing universal adhesives and self-adhesive composite cements presented brand-dependent higher SBS, even after aging. ICP-MS detected phosphorus release from all of the MDP-containing products. Microleakage was identified at the interfaces of all bonded specimens, with the highest rate detected in the Ctr group. Conclusion: MDP-containing primers, universal adhesives, and composite cements create bonds to zirconia with acceptable strength after long-term aging. Parole chiave: yttrium stabilized tetragonal zirconia polycrystals, phosphate ester monomer, MDP, bonding, primer, microleakage, ICP-MS, shear bond strength