Effect of Saliva Decontamination Protocols on Resin-Composite CAD/CAM Blocks

Objectives: To evaluate the effect of saliva contamination and the influence of different cleaning protocols on bonding performance and durability of resin-composite CAD/CAM blocks (RCBs).
Methods: Polymer infiltrated ceramic network RCB [PICN-RCB, Vita Enamic (En)] and dispersed filler RCB [DF-RCB, Estelite-P (ESTP)] were alumina-blasted on the adherent surfaces. Then, the RCBs slices were categorized into uncontaminated (Con) and 7 saliva-contaminated groups (n=24). Before cementation, saliva-contaminated slices were cleaned with one of the following methods: water-spray (WS), water-sonication (WU), ethanol (Eth), re-sandblasting (SB), 9.5% hydrofluoric acid (HF), KATANA cleaner (KC), and 40% phosphoric acid (PA). Chemical pretreatment with a mixture of CLEARFIL TRI-S BOND Universal and Porcelain Bond Activator (Kuraray Noritake Dental Inc.) was applied for all groups. RCBs slices were cemented with their counterpart using Panavia V5 cement. Microtensile bond strength (μTBS) test was performed after 24-hours (24h) and 10,000 thermocycling (TC) process. Surface roughness parameters [arithmetical mean height (Sa), and developed interfacial area ratio (Sdr)], and critical surface energy (γc) were measured. The Weibull analysis was performed for μTBS data.
Results: Saliva contamination resulted in decreasing the bond strength for both RCBs (p<0.05). KC revealed the highest µTBS among tested groups for En even compared with control at 24h (p<0.05). However, there was no statistically significant difference among Con, PA, HF, and KC groups after TC (p>0.05). While HF showed significantly higher µTBS in both 24h and TC for ESTP-RCB (p<0.05). Both HF and PA increased the total-γc for both RCBs. While KC improved only polar-γc for tested RCBs. SB and HF increased surface roughness parameters for both substrates.
Conclusions: The application of KC, HF, and PA could effectively clean PICN-RCB. On the other hand, decontamination of DF-RCBs with HF could be a better choice than KC and PA.