ABSTRACT
PURPOSE: This study evaluated the effects of peripheral enamel margins on the long-term bond strength (µTBS) and nanoleakage in resin/dentin interfaces produced by self-adhesive and conventional resin cements. MATERIALS AND METHODS: Five self-adhesive [RelyX-Unicem (UN), RelyX-U100 (UC), GCem (GC), Maxcem (MC), Set (SET)] and 2 conventional resin cements [RelyX-ARC(RX), Panavia F(PF)] were used. An additional group included the use of a two-step self-etching adhesive (SE Bond) with Panavia F (PS). One hundred ninety-two molars were assigned to 8 groups according to luting material. Five-mm-thick composite disks were cemented and assigned to 3 subgroups according to water-exposure condition (n = 6): 24-h peripheral exposure (24h-PE-enamel margins), or 1 year of peripheral (1 yr-PE) or direct exposure (1 yr-DE-dentin margin). Restored teeth were sectioned into beams and tested in tension at 1 mm/min. Data were analyzed by two-way ANOVA and Tukey's test. Two additional specimens in each group were prepared for nanoleakage evaluation. Nanoleakage patterns were observed under SEM/TEM. RESULTS: Except for RX, no significant reduction in µTBS was observed between 24h-PE and 1 yr-PE. 1 yr-DE reduced µTBS for RX, PF, GC, MC, and SET. No significant reduction in µTBS was observed for PS, UC, and UN after 1 year. After 1 yr-DE, RX and PS presented the highest µTBS, and SET and MC the lowest. Nanoleakage was reduced when there was a peripheral enamel margin. SET and MC presented more silver deposition than other groups. CONCLUSION: The presence of a peripheral enamel margin reduced the degradation rate in resin/dentin interfaces for most materials. The µTBS values produced by the multi-step luting agents RX and PS were significantly higher than those observed for self-adhesive cement.
Subject(s)
Dental Bonding , Dental Leakage , Resin Cements/chemistry , Analysis of Variance , Composite Resins , Dental Bonding/methods , Dental Enamel , Dental Stress Analysis , Dentin , Humans , Materials Testing , Microscopy, Electron , Molar , Statistics, Nonparametric , Tensile Strength , WaterABSTRACT
STATEMENT OF PROBLEM: Several self-adhesive luting agents have recently been introduced on the market. It is crucial to know the effectiveness of such luting agents prior to their clinical application. PURPOSE: The purpose of this study was to evaluate the microtensile bond strengths (microTBS) produced by different self-adhesive cements and compare them with conventional luting agents. MATERIAL AND METHODS: Six self-adhesive cements (RelyX Unicem (UN), RelyX U100 (UC), SmartCem 2 (SC), G-Cem (GC), Maxcem (MC), and SeT (SET), and 2 conventional luting agents, one that uses a 2-step etch-and-rinse adhesive (RelyX ARC (RX)), and one that uses a 1-step self-etching adhesive (Panavia F (PF)), were used in this study. An additional group included the use of a 2-step self-etching primer adhesive system (Clearfil SE Bond) prior to the application of Panavia F (PS). Fifty-four human molars were abraded to expose occlusal surfaces and were assigned to 9 groups according to the luting material (n=6). Five composite resin (Filtek Z250) discs (12 mm in diameter, 5 mm thick) were cemented on the teeth according to manufacturers' instructions. After 24 hours of water storage, restored teeth were serially sectioned into beams with a cross-sectional area of approximately 1 mm2 at the bonded interface and were tested in tension with a crosshead speed of 1 mm/min. Failure mode was determined using scanning electron microscopy. Data were statistically analyzed by 1-way ANOVA and Tukey's studentized range HSD test (alpha =.05). RESULTS: Mean bond strengths (SD) in MPa were: RX, 69.6 (16.6)A; PS, 49.2 (9.7)A; PF, 33.7 (13.9)AB; GC, 16.9 (10.3)BC; UC, 15.3 (3.4)BC; UN, 12.5 (2.4)C; MC 11.5 (6.8)CD; SC, 8.5 (4.9)CD; SET, 4.6 (0.5)D. Groups with different uppercase letters were significantly different from each other (P<.05). The predominant failure mode of the self-adhesive cements was adhesive between the resin cement and dentin. CONCLUSIONS: The bond strengths produced by the multistep luting agents were significantly higher than those observed for most self-adhesive cements.
Subject(s)
Dental Bonding , Dental Cements/chemistry , Bisphenol A-Glycidyl Methacrylate/chemistry , Cementation/methods , Composite Resins/chemistry , Dental Enamel/ultrastructure , Dental Etching , Dental Stress Analysis/instrumentation , Humans , Materials Testing , Methacrylates/chemistry , Microscopy, Electron, Scanning , Molar/ultrastructure , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Resin Cements/chemistry , Stress, Mechanical , Tensile Strength , Time Factors , Water/chemistryABSTRACT
The esthetic success of a dental treatment depends on the correct diagnosis, treatment plan and clinical and laboratory procedures. This clinical report describes a diagnostically based protocol for conservative preparations on anterior teeth for adhesively retained composite and porcelain restorations. The diagnostic additive wax-up, periodontal esthetic crown-lengthening, direct acrylic mock-up, conservative preparations for ceramic laminate veneers, luting procedures, direct restorations with composite resin used for the esthetic rehabilitation of a patient presenting conoid lateral incisors, and an unsatisfactory class IV restoration in the left central incisor are presented. An accurate diagnostic and interdisciplinary approach is necessary for obtaining improved, conservative and predictable esthetic results in esthetically compromised areas, such as the anterior maxillary dentition.
