In vitro and In vivo Evaluationof Different Gingival Retraction Cords

Modern impression techniques used in restorative dentistry require displacementof gingival tissue to expose the subgingival finish lines on the tooth preparation. Many different medications are used on gingival retraction cords in order to minimize hemorrhage from the gingival sulcus during impression making. A common method of accomplishing gingival displacement is by packing cord into the gingival crevice. This is especially critical when using hydrophobic impression materials such as polyvinyl siloxanes. The purpose of this study was to determine whether any of the commonly used gingival retraction medications could inhibit the polymerization of polyvinyl siloxane impression materials when they are in direct contact with the setting material and to evaluate the clinical performance of retraction cords. Many gingival retraction cords in various shapes, sizes and medications are available on the market. The literature is replete with reports on the effects of medicated and non-medicated cords on impression and gingival tissue. In this study, the number of the criteria of evaluation was increased and both in vitro and in vivo studies were conducted together by three prosthodontists

Pilot study of unidirectional E-glass fibre-reinforced composite resin splints: up to 4.5-year clinical follow-up

OBJECTIVES: This prospective clinical pilot study evaluated the performance of fibre-reinforced-composite resin (FRC) splints on mandibular anterior teeth. METHODS: Between June-2003 and January-2008, 19 patients (7 females, 12 males, 45-72 years old) from a group of consecutive patients who completed periodontal therapy received E-glass FRC splints (everStick Perio, StickTech) in combination with two types of flowable and restorative resin-composites (Filtek Flow, Filtek Supreme, n=11; Tetric Flow, Tetric-Ceram, n=8). Only patients with vital teeth, presenting mobility of grade 3, having at least one canine with no mobility on both sides of the dental arch were assigned for a splint therapy. The patients were recalled for periodical follow-up controls first at 6 months and thereafter annually. The evaluation protocol involved technical failures [chipping, debonding or fracture (tooth/restoration)] and biological failures (caries)]. Periodontal pocket depth (PPD) and clinical attachment level (CAL) were measured 6 months after splinting and annually. Six sites were measured for each natural tooth at the mesiobuccal, buccal, distobuccal, distolingual, lingual and mesiolingual sites. RESULTS: All splints were applied from canine to canine in the mandible. In total, 5 recalls were performed and no drop-out was experienced. One partial debonding of the FRC splint with Tetric Flow/Tetric-Ceram combination was observed after 40 months. No caries was found around any of the splints and no teeth had to be extracted until the final follow up. The splinted teeth were found to be vital in the vitality tests. Overall survival rate was 94.8% (Kaplan-Meier). The survival rate was not significantly affected by the composite type (Filtek-Flow/Filtek Supreme: 100%, Tetric Flow/Tetric Ceram: 96% (p=0.92) [Kaplan-Meier, Log Rank (Mantel-Cox) (CI=95%)]. Hazard ratio for Tetric Flow/Tetric Ceram group was 0.05 (95% CI) and for Filtek Flow/Filtek Supreme group 0.00 (95% CI). Whilst overall PPD measurements of the dentition ranged between 6 and 12 mm, the CAL measurements ranged between 4.9 and 10mm at baseline. The mean PPD for the splinted teeth decreased from 8.9±1.8 mm to 5.2±1.2 mm, and CAL decreased from 7.2±1.6 mm to 4.6±1 mm at the end point. CONCLUSION: Direct tooth splinting with E-glass FRC material performed successfully up to 4.5 years. Periodontal status of the splinted teeth showed decreased PPD and CAL

Fracture strength of fiber-reinforced surface-retained anterior cantilever restorations

PubMed ID: 18548961Purpose: This study compared the fracture strength of direct anterior cantilever fiber-reinforced composite (FRC) fixed partial dentures (FPD) reinforced with 3 types of E-glass fibers preimpregnated with either urethane tetramethacrylate, bisphenol glycidylmethacrylate/polymethyl methacrylate, or bisphenol glycidylmethacrylate monomers and 1 ultrahigh molecular weight polyethylene fiber. Failure types were also evaluated. Materials and Methods: A total of 40 caries-free, human maxillary central incisors (n = 10 per group) received surface-retained direct cantilever restoration (1 pontic) after etching and application of bonding agent. Four FRC materials were used (FRC1 = EverStick; FRC2 = BR-100; FRC3 = Interling; FRC4 = Ribbond), and pontics were built up using 1 particulate filler composite (Clearfil Photo Posterior). After the fracture test, failure types were analyzed. Results: No significant difference was found between the 4 FRC types veneered with particulate filler composite (893 ± 459 N to 1326 ± 391 N) (P = .1278). Complete pontic fracture at the connector area was most prominent for FRC4 (90%), followed by FRC3 (70%). Only FRC2 (10%) showed some fiber fractures, with half of the fiber remaining attached on the enamel surface of the abutment. Conclusion: The fracture strengths of cantilever FPDs made of 4 FRC materials with different monomer matrices and architectures, veneered with particulate filler composite, did not show significant differences. However, failure behavior varied between groups

Intra-oral adhesive systems for ceramic repairs: a comparison

WOS: 000187413900003PubMed ID: 14763777The aim of this investigation was to compare the bond strength of restorative composite resin to dental ceramic conditioned with primers and adhesives of various commercial repair kits. Three intra-oral ceramic repair systems-Silistor (Heraeus Kulzer), Cimara (Voco), Ceramic Repair (Vivadent)-were used on all-ceramic (IPS Empress 2, Ivoclar-Vivadent) substrate. Shear bond strength of restorative composite resin to substrate was tested after thermocycling and without thermocycling (n = 10). Substrate surfaces of the specimen after loading were examined microscopically (SEM). The highest bond strengths in both water-stored (7.0 +/- 5.7 MPa) and thermocycled conditions (2.5 +/- 1.8 MPa) were obtained with the Vivadent repair system, while the lowest values were observed with the Cimara system (0.6 +/- 1.4 MPa and 0.0 +/- 0.0 MPa, respectively). Shear bond strengths appeared to be significantly affected by thermocycling (ANOVA, P< 0.05). It is concluded that there are significant differences in the bond strengths of resin composites and ceramic substrate. The roughened surface does not necessarily provide a better bond strength; the bond strength of composite decreases with storage in water and after thermocycling. Bond strength values were generally low for all of the tested materials