Effect of primers and resins on the shear bond strength of resin composite to zirconia

Objective. To evaluate the effects of various surface conditioning methods and agents. Methods. The intaglio zirconia substrates were air particle abraded with Al2O3 (Ø 50 μm) for 10 s. An air pressure of 450 kPa and a nozzle distance of 10 mm were used. Surface conditioning by groups: A = silane coupling agent  + organophosphate adhesive; B = organophosphate primer + silane coupling agent + organophosphate adhesive; C = organophosphate primer; D = methacrylate adhesive; E = thiophosphate primer + methacrylate adhesive. Composite stubs were bonded to substrates and photo-polymerized. The specimens were thermocycled 8000 times 55±1∘C and 5±1∘C and kept in distilled water for 14 d. The shear bond strengths were measured with a universal testing machine. Results. Shear bond strengths (MPa ± SD): Group A 25.8±6.7, Group B 26.5±8.6, Group C 16.7±8.5, Group D 2.6±0.7, and Group E 4.2±1.2. ANOVA: significant differences among groups (P<.05). Groups A and B: mainly cohesive fractures, Group C: mixed or adhesive fractures, Groups D and E: adhesive fractures. Conclusions. A value of 10–13 MPa is the minimum acceptable shear bond strength. Groups A, B, and C exceeded this limit, Groups D and E could not achieve the limit.published_or_final_versio

Thermocycling effects on resin bond to silicatized and silanized zirconia

Various techniques have been introduced to create a durable resin composite bond to sintered zirconia (Y-TZP). Shear bond strength values achieved through tribochemical treatment have been investigated in numerous studies, but less is reported about long-term durability. The objective here was to evaluate the effects of thermocycling and silane on shear bond strength of a composite luting cement to silicatized Y-TZP. Two groups of Y-TZP (Procera Zirconia, Nobel Biocare), both consisting of 40 specimens were prepared. The specimen surfaces were air particle abraded with silica-coated aluminum trioxide particles (particle size 110 μm, duration 15 s, air pressure 300 kPa, nozzle distance 10 mm). The silica-coated surfaces in group ZA were silanized with an acrylate-functional silane (Experimental laboratory-made acrylate silane, Toray Dow Corning Silicone) and in the other group ZM with a pre-activated methacrylate silane (ESPE Sil, 3M ESPE). The surfaces were coated with adhesive system (Scotchbond 1, 3M ESPE) and photo-polymerized for 10 s. Resin composite luting cement (RelyX ARC, 3M ESPE) stubs were bonded to substrates and photo-polymerized for 40 s. The test specimens were thermocycled for 0, 1000, 3000, 8000 or 15 000 times (temperature 5-55°C, exposure time 20 s). The shear bond strengths of luting cement to ceramics were measured with a crosshead speed of 1.0 mm/min. ANOVA was used for statistical analysis. ANOVA revealed that both silane and thermocycling affected significantly (p < 0.001) the shear bond strength. Short term hydrolytic stability of acrylate silane was superior. It was concluded that evaluation of bonding requires extended thermocycling. © 2009 VSP.postprin

Load-bearing capacity of human incisor restored with various fiber-reinforced composite posts

Objectives. The aim of this study was to evaluate the load-bearing capacity and microstrain of incisors restored with posts of various kinds. Both prefabricated titanium posts and different fiber-reinforced composite posts were tested.Methods. The crowns of human incisors were cut and post preparation was carried out. The roots were divided into groups: (1) prefabricated serrated titanium posts, (2) prefabricated carbon fiber-reinforced composite posts, (3) individually formed glass fiber-reinforced composite posts with the canal full of fibers, and (4) individually formed "split" glass fiber-reinforced composite posts. The posts were cemented and composite crowns were made. Intact human incisors were used as reference. All roots were embedded in acrylic resin cylinders and stored at room temperature in water. Static load was applied under a loading angle of 45 degrees using a universal testing machine. On half of the specimens microstrain was measured with strain gages and an acoustic emission analysis was carried out. Failure mode assessment was also made.Results. The group with titanium posts showed highest number of unfavorable failures compared to the groups with fiber-reinforced composite posts. Significance. With fiber-reinforced composite posts the failures may more often be favorable compared to titanium posts, which clinically means repairable failures. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved

Fiber-reinforced Composite for Chairside Replacement of Anterior Teeth: A Case Report

A variety of therapeutic modalities, from implant to conventional Maryland prosthesis, can be used for the replacement of a missing anterior tooth. Whenever a minimal tooth reduction is preferred, a fiber reinforced composite (FRC) prosthesis could be a good alternative to conventional prosthetic techniques, chiefly as temporary restoration before making a final decision on the treatment. The purpose of this case report is to describe the clinical procedure of fabricating anterior chairside FRC prosthesis with pre-impregnated unidirectional E-glass fibers and veneered particulate filler composite. Fiber-reinforced composite in combination with adhesive technology appears to be a promising treatment option for replacing missing teeth. However, further and long-term clinical investigation will be required to provide additional information on the survival of directly-bonded anterior fixed prosthesis made with FRC systems

The Effect of Chlorhexidine and Dimethyl Sulfoxide on Long-Term Microleakage of Two Different Sealers in Root Canals

Objective: The aim of root canal obturation is to prevent leakage and inhibit microbial invasion. This study aimed to determine the effect of chlorhexidine (CHX) and dimethyl sulfoxide (DMSO) as final irrigants on microleakage of root filling immediately and after 18 months. The hypothesis was that either CHX or DMSO would not affect the immediate or long-term microleakage.Methods: A total of 120 human third molar root canals were obturated with RealSeal SE or Topseal and gutta percha. Before obturation, the canals were irrigated with saline (control), 2% CHX or 5% DMSO. Microleakage of half of each groups (n=10) was measured after 3 days, and of the other half was measured after 18 months with fluid filtration method.Results: In immediate measurements, RealSeal SE performed significantly better in CHX-irrigated group (p=0.035; Mann-Whitney test). For both sealers, DMSO had the lowest mean microleakage values, which were also statistically significantly lower than with CHX irrigation within sealers (p<0.009 for Topseal and p=0.04 for RealSeal SE; Mann-Whitney test). With RealSeal SE, the microleakage with CHX was significantly higher than that in controls (p=0.022; Mann-Whitney test).Conclusion: Neither final irrigant showed statistically significant differences in the immediate microleakage within the two sealers. Irrigation with DMSO caused significantly less microleakage than CHX for both sealers after 18 months

Fracture behavior of single-structure fiber-reinforced composite restorations

Objective: The applications of single-structure fiber-reinforced composite (FRC) in restorative dentistry have not been well reported. This study aimed to clarify the static mechanical properties of anterior crown restorations prepared using two types of single-structure FRC. Materials and methods: An experimental crown restoration was designed for an upper anterior incisor. The restorations were made from IPS Empress CAD for CEREC (Emp), IPS e.max® CAD (eMx), experimental single-structure all-FRC (a-FRC), Filtek™ Supreme XTE (XTE), and commercially available single-structure short-FRC (everX Posterior™) (n = 8 for each material) (s-FRC). The a-FRC restorations were prepared from an experimental FRC blank using a computer-aided design and manufacturing (CAD/CAM) device. A fracture test was performed to assess the fracture load, toughness, and failure mode. The fracture loads were vertically applied on the restorations. The surface micromorphology of the FRC restorations was observed by scanning electron microscopy (SEM). The data were analyzed by analysis of variance (p = .05) followed by Tukey's test. Results: s-FRC showed the highest mean fracture load (1145.0 ± 89.6 N) and toughness (26.2 ± 5.8 Ncm) among all the groups tested. With regard to the micromorphology of the prosthetic surface, local crushing of the fiberglass was observed in s-FRC, whereas chopped fiberglass was observed in a-FRC. Conclusions: The restorations made of short-FRC showed a higher load-bearing capacity than those made of the experimental all-FRC blanks for CAD/CAM. The brittle-like fractures were exhibited in the recent dental esthetic materials, while local crushing fractures were shown for single-structure FRC restorations.</p

Preliminary Clinical Evaluation of Short Fiber-Reinforced Composite Resin in Posterior Teeth: 12-Months Report

This preliminary clinical trial evaluated 12 month clinical performance of novel filling composite resin system which combines short fiber-reinforced composite resin and conventional particulate filler composite resin in high stress bearing applications. A total of 37 class I and II restorations (compound and complex type) were placed in 6 premolars and 31 molars. The restorations were reviewed clinically at 6 months (baseline) and 12 months using modified USPHS codes change criteria for marginal adaptation, post-operative sensitivity, pulpal pain and secondary caries criteria. Photographs and x-rays were obtained for restorative analysis. Results of 12 months evaluation showed 5 restorations having little marginal leakage (B score) and 1 patient had minor pulpal symptom and post-operative sensitivity (B score). No secondary caries or bulk fracture was detected. The majority of restorations exhibited A scores of the evaluated criteria. After 12 months, restorations combining base of short fiber reinforced composite resin as substructure and surface layer of hybrid composite resin displayed promising performance in high load bearing areas

E-Glass Fiber Reinforced Composites in Dental Applications

Fiber reinforced composites (FRCs) are more and more widely applied in dentistry to substitute for metallic restorations: periodontal splints, fixed partial dentures, endodontic posts, orthodontic appliances, and some other indirect restorations. In general in FRCs, the fiber reinforcement provides the composite structure with better biomechanical performance due to their superior properties in tension and flexure. Nowadays, the E-glass fiber is most frequently used because of its chemical resistance and relatively low cost. Growing interest is being paid to enhance its clinical performance. Moreover, various techniques are utilized to reinforce the adhesion between the fiber and the matrix. Oral conditions set special requirements and challenges for the clinical applications of FRCs. The biomechanical properties of dental materials are of high importance in dentistry, and given this, there is on-going scientific interest to develop E-glass fiber reinforced composite systems. FRCs are generally biocompatible and their toxicity is not a concern. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201