Effect of powder air polishing and ultrasonic scaling on the marginal and internal interface (tooth-veneer) of ceramic veneers: an in vitro study.

Objectives: This study investigated the influence of prophylactic treatments and thermocycling on the marginal and internal veneering interface (tooth-veneer) as well as on the surface texture of ceramic veneers.

Materials and methods: A total of 32 extracted human premolars were restored with veneers made of lithium disilicate (LDS) or zirconia-reinforced lithium silicate (ZLS). An artificial aging of the specimens was conducted via five cycles of both thermocycling (5/55°C) and prophylactic treatment (powder air polishing or ultrasonic scaling). Changes in the marginal interface and in the surface texture were examined using confocal laser scanning microscopy. The internal interface and the microstructure were investigated using micro X-ray computed tomography.

Results: Artificial aging resulted in a deepening of the marginal interface across all groups (mean height: 4.51-15.74 μm, maximum height: 10.42-22.71 μm, cross-section: 256.68-1525.84 μm², regardless of the veneer material or prophylaxis method. No change in surface texture was observed. The internal interface exhibited defects for all groups after artificial aging. ZLS showed cracks in five out of eight veneers after exposure to ultrasonic scaling and thermocycling.

Conclusion: Ceramic veneers exhibited a high resistance to prophylactic measures in terms of surface durability, but a deepening of the marginal interface should be taken into account. With regard to the formation of cracks within the material, the use of ultrasonic scaling is not recommended for ZLS veneers.

Clinical relevance: The influence of artificial aging, including prophylactic treatments, plays a critical role in assessing longevity for veneers in defect-oriented and esthetic dentistry.