Effects of primers on the microtensile bond strength of resin cements to cobalt-chromium alloy / 대한치과보철학회지

PURPOSE: The aim of this study is to evaluate the effects of various primers on the microtensile bond strength (µTBS) of resin cements to cobalt-chromium (Co-Cr) dental casting alloy. MATERIALS AND METHODS: Four adhesive primers (Universal primer, Metal primer II, Alloy primer, and Metal/Zirconia primer) and two resin cements (Panavia F2.0, G-CEM LinkAce) were tested. One hundred fifty Co-Cr beams were prepared from Co-Cr ingots via casting (6 mm length × 1 mm width × 1 mm thick). The metal beams were randomly divided into ten groups according to the adhesive primers and resin cements used; the no-primer groups served as the control (n = 15). After sandblasting with aluminum oxide (125 µm grain), the metal and resin cements were bonded together using a silicone mold. Prior to testing, all metal-resin beams were examined under stereomicroscope, and subjected to the µTBS test. The mean value of each group was analyzed via one-way ANOVA with Tukey's test as post hoc (α = .05) using SPSS software. RESULTS: The mean µTBS of all groups was ranged from 20 to 28 MPa. There is no statistically significant difference between groups (P > .05). Mixed failure, which is the combination of adhesive and cohesive failures, is the most prevalent failure mode in both the Panavia F2.0 and G-Cem LinkAce groups. CONCLUSION: The µTBS of all tested groups are relatively high; however, the primers used in this study result in no favorable effect in the µTBS of Panavia F2.0 and G-Cem LinkAce resin cement to Co-Cr alloy.

Flexibility of resin splint systems for traumatized teeth / 대한치과보철학회지

PURPOSE: The aim of this study is to evaluate the flexural strength of flexible resins and the flexibility of different resin splint (RS) systems in comparison with resin wire splint (RWS) system. MATERIALS AND METHODS: Three different resin materials (G-aenial flo, GA, GC; Superbond, SB, Sun medical; G-fix, GF, GC) were tested flexural strength test in accordance with ISO-4049:2000. For the flexibility test of splint systems, a artificial model with resin teeth was used to evaluate three types of resin splint systems (GA, SB, and GF) and one resin wire splint system. The left central incisor was simulated ‘injured teeth’ with third degree mobility. Three consecutively repeated measurements of periotest value were taken in horizontal direction, before and after splinting to access tooth mobility. The splinting effect was calculated through the periotest value. Differences were evaluated through One-way Anova and Tukey HDS post-hoc tests for pair-wise comparison (α= .05). RESULTS: Although GA group showed significant higher flexural strength than SB and GF groups, all of three different resin splint systems produced a significantly higher and rigid splinting effect compared with 016" resin-wire splint system (P < .05). CONCLUSION: Within the limits of an in vitro study, it can be stated that resin splint systems are too rigid and may not be acceptable to treat tooth avulsion.

Management of horizontal root fractures by fabrication of canine protected occlusion using composite resin

Traumatic injuries of the face often involve root fractures especially in anterior teeth. The prognosis and the treatment of the root fracture depend on the extent of the fracture line, general health and patient compliance. This case report outlines a new conservative trial treatment modality to stabilize the maxillary central incisors with horizontal root fracture on the cervical to middle third by fabricating canine guidance to remove loading on the traumatized maxillary central incisors during eccentric movements and thus inducing spontaneous healing of the fractured line between the fragments. Radiographs after thirty months showed adequate healing with no signs of pathological changes including root resorption, ankylosis or displacement. Long term follow-up revealed that vitality, stability and aesthetics were maintained and the patient was satisfied with the outcome.

BONE REGENERATION WITH INJECTABLE MPEG-PCL DIBLOCK COPOLYMER AND BONE MARROW MESENCHYMAL STEM CELL

Effects of activators contained in adhesives on dentin bond strengths / 대한치과보철학회지

STATEMENT OF PROBLEM: An incompatibility between the initiator systems of self-curing composite resins and light-curing adhesives was supposed recently. PURPOSE: The purpose of the study was to evaluate the influence of activators for self/dual bonding on dentin shear bonding strengths. MATERIAL AND METHODS: Fifty human molars were divided into 5 groups. A flat dentin surface was created for each tooth. A self-curing composite resin (Luxacore) was bonded with the following adhesives (n = 10): One-Step, Prime and Bond NT, AdheSE, Prime and Bond NT and AdheSe were also used in combination with activators. Shear bond strengths were measured after 24 hours of water storage. The specimens were loaded in shear in the Instron until failure at a 1 mm/min crosshead speed. Data were compared using one-way ANOVA and Tukey HSD test (alpha = 0.05). RESULTS: The dentin adhesive systems in order of decreasing median bond strength were One-Step > Prime & Bond NT with activator, AdheSe with activator > Prime and Bond NT, AdheSe. Among adhesives, One-Step had the highest bond strength. Prime & Bond NT with activator had higher bond strengths than Prime and Bond NT that was used alone, and so was AdheSe. CONCLUSION: Shear bond strengths were increased in Prime and Bond NT and AdheSe when these were used with activators comparing used without activators. But using activators was not effective clinically comparing One-Step.