Objectives: The usage of CAD/CAM-manufactured single implant restorations is a common method in prosthetic dentistry. Several benefits lead to an adhesive connection of individualized ceramic crowns and prefabricated titanium bonding bases. However, the bonding has to resist permanent thermal, chemical and mechanical stress in the oral cavity. The durability of the bonding is a weak point and especially dependent on sufficient surface pretreatment. Cold atmospheric pressure plasma (CAP) is a conventional method for improving surface characteristics in car industry and space engineering. The aim of this study was to evaluate the impact of CAP on shear bond strength in two-piece abutments.
Methods: Two different pretreatment protocols were tested in this study. Ten CAD/CAM-manufactured and sintered crowns of zirconia and ten prefabricated titanium bonding bases were divided into 2 groups (n=5): (A) as specified by the manufacturer (sandblasting (Al2O3, 50μm, 1bar) + adhesive primer (Ceramic Bond, VOCO GmbH, Cuxhaven, Germany)), (B) sandblasting + CAP + adhesive primer. Optimal pretreatment with CAP (piezobrush PZ2, relyon plasma GmbH, Regensburg, Germany) was evaluated in pretrial studies by analyzing water contact angles on polished surfaces after different duration of exposure. The wetting properties suggested a minimal CAP application time of 15 seconds. After pretreating the interfaces, the pieces were glued together under standardized pressure by using Bifix Hybrid-Abutment-Cement by VOCO. The specimens were thermocycled for artificial aging and then shear bond strength (SBS) was measured.
Results: The SBS in two-piece abutments pretreated with CAP was higher than in those without. Mean values differed significantly (Mann-Whitney-Test, p=0.008) from 601.6±86.3N (Group A) to 755.0±37.2N (Group B).
Conclusions: The study showed that additional usage of CAP for surface pretreatment in two-piece abutments leads to a significant increase of shear bond strength by about 25%. Thus, CAP can be recommended as a pretreatment procedure in this special field of indication. Further investigations by using different ceramic materials and luting cements are intended.