Studies have failed to identify the molecular mechanisms that regulate the genotoxic and cytotoxic effects of methacrylate resins, which are important in the biocompatibility of dental materials. Interleukin (IL)-6 has a crucial role in the control of acute-phase protein response during inflammation. In humans, the synthesis and release of two major acute-phase proteins, C-reactive protein and serum amyloid A, are regulated by IL-6. This study focused on IL-6 and activation of its receptors gp80 and gp130 in human gingival fibroblasts in order to assess the effects of the commercial acid resins Jet Kit, Unifast, and Duralay on control of inflammation.
This study evaluated the combined influence of horizontal bone loss and post length on the fracture resistance of endodontically treated teeth (ETT). Twenty premolars were endodontically treated and divided into four groups of two different post insertion depths (5 and 7 mm) and two alveolar bone levels from cement-enamel junction (2 and 5 mm). After posts (RelyX Fiber Post) were cemented using a self-adhesive resin cement (RelyX Unicem Aplicap) and cores were built up (Filtek Supreme XT Universal Restorative, 3M ESPE, USA), cobalt-chrome copings were luted to each prepared tooth. All specimens were subjected to thermocycling and mechanical loading until fracture occurred. Mean fracture loads (N) were 1,445±342.2 (2 mm bone level/5 mm depth), 1,516±413.4 (2 mm bone level/7 mm depth), 1,736.4±1113.8 (5 mm bone level/5 mm depth), 1,038.6±600.2 (5 mm bone level/7 mm depth). No significant differences were found. Therefore, bone level and post length did not seem to influence the fracture resistance of ETT.
To evaluate residual dentin thickness (RDT) after different tooth preparations, 90 sound maxillary anterior teeth were selected and divided into 3 groups according to tooth type (n = 30), namely, maxillary central incisors, maxillary lateral incisors, and maxillary canines. In each group, specimens were randomly divided and prepared for single-crown coverage with shoulder (SHO, n = 10, control), slight chamfer (CHA, n = 10), and knife-edge (KNE, n = 10) finish lines. After tooth preparation, specimens were sectioned and divided into 4 subgroups (buccal, distal, palatal, and mesial) according to measurement area. RDT values were compared by using one-way ANOVA and Tukey's post hoc test (P = 0.05). Significant differences were found between SHO and the other two groups (P < 0.05) but not between CHA and KNE (P > 0.05). SHO was significantly more aggressive than CHA and KNE, which were comparable. Interproximal areas became critical due to thin RDT, which could potentially compromise the structural and biological integrity of teeth. The choice of finish line should be guided by careful clinical evaluation. (J Oral Sci 55, 79-84, 2013)
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