Fatigue behavior of dental resin composites: flexural fatigue in vitro versus 6 years in vivo.
ABSTRACT To evaluate fatigue behavior of direct resin composite restorations (Tetric Ceram vs. Grandio) in vitro and in vivo over an observation period of 6 years.
For the in vitro part, Young's moduli (YM) were calculated and both initial (FS: flexural strength) and fatigue flexural strength (FFL: flexural fatigue limit) were evaluated in a four-point bending setup (n = 15) in distilled water at 37°C. For the in vivo part, 30 patients received 68 direct resin composite restorations of the same materials (Grandio bonded with Solobond M; Tetric Ceram bonded with Syntac). Patients revealed a minimum of two different class II restorations in different quadrants. Epoxy replicas of restored teeth were analyzed under a scanning electron microscope (SEM) at 30× magnification for fatigue characteristics, and 11 selected restorations per group were assessed for marginal fatigue characteristics at 200×.
In vitro, YM was 15.7 GPa (Grandio) and 8.7 GPa (Tetric Ceram; p < 0.05), FS was 115.0 MPa (Grandio) versus 101.5 MPa (Tetric Ceram; p > 0.05), and FFL was 63.0 MPa (Grandio) versus 44.3 MPa (Tetric Ceram; p < 0.05). In vivo, no significant difference in fatigue behavior (cracks, chippings) was evaluated for the different materials under investigation. However, marginal breakdown was more pronounced under the SEM for Tetric Ceram (7.9% vs. 4.8% for Grandio; p < 0.05), but without being clinically relevant. SEM analysis exhibited distinct wear patterns after 6 years with no significant differences among materials as well.
Despite higher in vitro values for YM, FS, and FFL for Grandio, clinical outcome for both resin composite materials over 6 years of clinical service was similar. Higher FFLs in vitro seem to be related to less marginal composite fractures in vivo but without any influence on clinical outcome until the 6 years recall.
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ABSTRACT: Packable composites, promoted for the restoration of stress-bearing posterior teeth, have captured clinicians' interest. The authors tested three packable composites (Alert, Jeneric/Pentron; Solitaire, Heraeus Kulzer, Wehrheim, Germany; SureFil, Dentsply De Trey, Konstanz, Germany); a new packable organically modified ceramic, or ormocer (Definite, Degussa AG, Hanau, Germany); a hybrid composite (Tetric Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) and an ion-releasing composite (Ariston pHc, Ivoclar Vivadent, Schaan, Liechtenstein). They determined modulus of elasticity according to EN 24049:1993 of the European Committee for Standardization. They measured Vickers hardness using a 200-gram load for 40 seconds. To determine the materials' depth of cure, they used both a scraping method (International Standards Organization standard CD 4049:1997) and a hardness profiling method. The authors calculated means and standard deviations from 10 replications of each test and used one-way analysis of variance and post hoc Tukey tests (alpha = .05). The materials had significant differences (P < .001) in all characteristics. Solitaire had the significantly lowest elastic modulus and microhardness; Alert had the highest values for these characteristics. Ariston pHc exhibited the significantly lowest depth of cure. There was a significant correlation between the two methods of measuring depth of cure (r2 = 0.9945; P = .021). The material group of packable composites is rather inhomogeneous in terms of mechanical and physical data. Our data suggest that bulk curing of packable composites in deep cavities still is not recommendable. The clinician needs to select packable composites carefully, as it seems that not all of these materials quality for stress-loaded posterior restorations.Journal of the American Dental Association (1939) 05/2001; 132(5):639-45. · 1.82 Impact Factor
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ABSTRACT: To evaluate the clinical behavior of two different resin composites in Class II cavities over a period of 2 years in a controlled prospective split-mouth study. 30 subjects received 68 direct resin composite restorations (Grandio bonded with Solobond M: n=36, Tetric Ceram bonded with Syntac: n=32) by one dentist in a private practice. All restorations were replacement restorations, 24 cavities (35%) revealed no enamel at the bottom of the proximal box, in 33 cavities (48%) the proximal enamel width was < 0.5 mm. The restorations were examined according to modified USPHS criteria at baseline, and after 0.5, 1, and 2 years. At each recall, impressions were taken to prepare replicas. Replicas of 44 selected subjects were assessed for marginal quality under a stereo light microscope (SLM) at x130, and 22 replicas were assessed under a SEM at x200. Both recall rate and survival rate were 100% after 2 years of clinical service. No significant difference was found between the restorative materials (P > 0.05; Mann-Whitney U-test). A significant deterioration was found over time for marginal integrity, tooth integrity, restoration integrity and proximal contact (P < 0.05; Friedman test). SLM and SEM analysis of restoration margins only revealed differences in the amount of detectable perfect margins, in favor of Tetric Ceram (P < 0.05). Both materials performed satisfactorily over the 2-year observation period.American journal of dentistry 08/2009; 22(4):228-34. · 1.06 Impact Factor
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ABSTRACT: Posterior composite restorations have been in use for approximately 30 years. The early experiences with this treatment indicated there were more clinical challenges and higher failure rates than amalgam restorations. Since the early days of posterior composites, many improvements in materials, techniques, and instruments for placing these restorations have occurred. This paper reviews what is known regarding current clinical challenges with posterior composite restorations and reviews the primary method for collecting clinical performance data. This review categorizes the challenges as those related to the restorative materials, those related to the dentist, and those related to the patient. The clinical relevance of laboratory tests is discussed from the perspective of solving the remaining clinical challenges of current materials and of screening new materials. The clinical problems related to early composite materials are no longer serious clinical challenges. Clinical data indicate that secondary caries and restoration fracture are the most common clinical problems and merit further investigation. The effect of the dentist and patient on performance of posterior composite restorations is unclear and more clinical data from hypothesis-driven clinical trials are needed to understand these factors. Improvements in handling properties to ensure void-free placement and complete cure should be investigated to improve clinical outcomes. There is a general lack of data that correlates clinical performance with laboratory materials testing. A proposed list of materials tests that may predict performance in a variety of clinical factors is presented. Polymerization shrinkage and the problems that have been attributed to this property of composite are reviewed. There is a lack of evidence that indicates polymerization shrinkage is the primary cause of secondary caries. It is recommended that composite materials be developed with antibacterial properties as a way of reducing failures due to secondary caries. Post-operative sensitivity appears to be more related to the dentin adhesives' ability to seal open dentinal tubules rather than the effects of polymerization shrinkage on cuspal deflections and marginal adaptation.Dental Materials 02/2005; 21(1):9-20. · 3.77 Impact Factor