Adhesion of resin cement to dentin: effects of adhesive promoters, immediate dentin sealing strategies, and surface conditioning.

PURPOSE: This study evaluated the shear bond strength (SBS) of resin cement to dentin after applying two adhesive (A) systems with a combination of four different immediate dentin sealing (IDS) strategies, and two surface conditioning (SC) methods. MATERIAL AND METHODS: Human third molars (n = 140) were collected and randomly split (n = 70 each) between the two A systems (Clearfil SE Bond; Kuraray [AC] and Optibond FL; Kerr [AO]). The A groups were further divided into four IDS strategies (2 x one adhesive layer (IDS-1L); 2 x two adhesive layers (IDS-2L); 2 x one adhesive layer and one flowable layer (IDS-F); 2 x no adhesive layer (delayed dentin sealing [DDS]). Finally, each strategy group was categorized into one of the two SC methods (only pumice [SC-P] or pumice and silica coating [SC-PS]), except the DDS group, where only SC-P was used. This resulted in 14 groups of 10 specimens each. The occlusal coronal third was removed from each molar crown with a diamond saw (Isomet 1000), and IDS was applied, followed by temporary restorations. These were removed after 2 weeks of water storage, and the IDS surfaces were subsequently conditioned. The standard adhesive procedure (Syntac Primer and Adhesive, Heliobond; Ivoclar Vivadent) was executed, followed by the application of a resin cement (Variolink II; Ivoclar Vivadent) and photopolymerization. All specimens were subjected to thermocyclic aging (10,000 cycles, 5°C to 55°C). Shear force was applied to the adhesive interface in a universal testing machine (1 mm/min). Fracture types and locations after loading were classified. The data were analyzed using analysis of variance (ANOVA) and independent samples t tests. RESULTS: AO groups exhibited higher mean SBS values (14.4 ± 6.43) than AC groups (12.85 ± 4.97) (P = 0.03). ANOVA showed the main effect of the applications on the SBS in the different groups (P = 0.00). Both DDS groups showed significantly lower SBS values compared with all the IDS groups (IDS-1L, IDS-2L, IDS-F). No significant differences in SBS results were found between the IDS groups (P = 0.43) and between the SC methods (P = 0.76). Dentin-cement interface failures diminished with the application of IDS. CONCLUSION: IDS improves the SBS compared with DDS. No significant differences were found between the tested conditioning methods.

The Clinical Performance of Monolithic Lithium Disilicate Posterior Restorations After 5, 10, and 15 Years: A Retrospective Case Series.

PURPOSE: Lithium disilicate (LDS) glass-ceramic restorations are routinely used, but results over a period longer than 10 years are rare. The objective of this study was to obtain long-term clinical data on monolithic LDS posterior crowns provided by a single restorative dentist. MATERIALS AND METHODS: Eligible patients who received a circumferential LDS crown in the posterior region between 1997 and 2010 were invited to participate in a clinical examination in 2015. This consisted of intraoral inspection and radiographs, performed by one observer and according to standardized criteria. Probability of survival was estimated using Kaplan-Meier survival analysis. RESULTS: A total of 13 patients (n = 87 restorations) fulfilled the inclusion criteria. Of these, 12 patients were available for clinical evaluation (n = 74 restorations). After 5, 10, and 15 years, the cumulative chance of survival of the restoration was 92%, 85.5%, and 81.9%, respectively, with a median observation period of 12.8 years. Of the 74 restorations, 13 failed: 4 because of secondary caries, 2 because of debonding, and 7 because of fracture of the restoration. CONCLUSION: Lithium disilicate can be regarded as a strong and fracture-load-resistant restorative material providing reliable long-term clinical performance.