Clinical Bonding of Resin Nano Ceramic Restorations to Zirconia Abutments: A Case Series within a Randomized Clinical Trial.

Abstract

New dental materials are introduced and promoted in the field without extensive clinical testing. Using those materials in a clinical setting might result in unacceptable early failure rates. The purpose of this paper was to analyze bonding of a new dental restorative material to either zirconia stock abutments or zirconia customized abutments. Fifty participants seeking single implant treatment were included in a prospective study. Resin Nano Ceramic (RNC, Lava Ultimate, 3M ESPE, Seefeld, Germany) crowns were digitally manufactured and extraorally bonded to either a stock or a customized zirconia abutment (ZirDesign and ATLANTIS, DENTSPLY Implants, Mölndal, Sweden) by means of a resin composite cement (RelyX Ultimate in combination with Scotchbond Universal, 3M ESPE), strictly following the manufacturer's recommendations. The final restorations were screw-retained to the implants and followed during 12 months. Primary outcome parameter was uncompromised survival of the restoration, and secondary outcome parameter was mode of failure. No implants were lost. The uncompromised survival rate of the RNC crowns bonded to zirconia abutments after 1 year of clinical service was only 14% (n = 7). Catastrophic failure occurred in three cases (6%), whereas bonding failure between RNC crowns and zirconia abutments occurred in 80% of the cases (n = 40) within the first year of service. No statistical significant difference in uncompromised survival rate could be identified between abutment types (χ2 = 1.495, p = .209). Uncompromised survival rate after 1 year was highly significantly different (χ2 = 104.173, p < .001) from a reference standard, which was set at 95%. RNC crowns luted to stock and customized zirconia implant abutments with the particular resin composite cement in this trial have a poor prognosis, regardless of the abutment type used.