OBJECTIVE: This in vitro study investigated the effect of immediate dentin sealing and provisional cements on micro tensile bond strength (μTBS) of resin bonded glass ceramic to dentin. METHOD AND MATERIAL: Occlusal surfaces of sixty maxillary premolars were cut perpendicular to the long axis of the teeth to expose dentin. A total of 60 pressable lithium disilicate glass ceramic specimens (Emax press, Ivoclar, FL) were laboratory fabricated. Prepared teeth were classified into 6 groups according to dentin conditioning as follow: Group 1:(C), freshly cut dentin (control group). Group 2: (IDS), immediate dentin sealing. Group 3:(IDS-RC), immediate dentin sealing plus resin based provisional cement (Provitemp, ITENA Clinical, France). Group 4: (IDS-CC), immediate dentin sealing plus conventional provisional cement (NTEC, Meta Biomed, South Korea). Group 5: (C-RC), dentin without sealing plus resin based provisional cement and Group 6: (C-CC), dentin without sealing plus conventional provisional cement. Universal adhesive (Tetric-N-bond universal, Ivoclar, FL) was used for IDS, then provisional restorations were temporarily inserted to prepared teeth using provisional cements. Test groups (IDS-CC, IDS-RC, CCC and C-RC) were covered with provisional restorations and kept in water bath for 2 weeks. Intaglio surfaces of ceramic specimens were etched using 9.5% hydrofluoric acid for 15 seconds then rinsed with water and ultrasonically cleaned for 3 minutes in 99% alcohol and air dried. Universal primer (Monobond N, Ivoclar, FL) was applied immediately to the etched intaglio surfaces. Selfadhesive resin cement (Multilink Speed, Ivoclar, FL) was mixed and applied to the intaglio surfaces of ceramic restorations. Then ceramic restorations were bonded to conditioned teeth, excess cement was removed. All specimens were light polymerization for 20 seconds from 4 directions. Finally bonded specimens were artificially aged as follow; one hour after bonding, specimens of all test groups were stored in water bath at 37°C for 5 months followed by thermal cycling for 5000 thermal cycles to simulate clinical condition. μTBS were recorded in MPa. Tukey's HSD test (P≤0.05) was used for statistical analysis. RESULTS: Compared to control group (C) (6.37±3.26), immediate dentin sealing significantly increased μTBS (P.05). CONCLUSION: Immediate dentin sealing had a significant impact on resin bonding to lithium disilicate glass ceramic.
Kamal et al. (Tue,) studied this question.