Light curing resin cements containing iodonium salts promote suitable apical bonding of posts to radicular dentin.

The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.

Light curing resin cements containing iodonium salts promote suitable apical bonding of posts to radicular dentin

Abstract The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.

Trends in restorative composites research: what is in the future?

Clinical trials have identified secondary caries and bulk fracture as the main causes for composite restoration failure. As a measure to avoid frequent reinterventions for restoration replacement, composites with some sort of defense mechanism against biofilm formation and demineralization, as well as materials with lower susceptibility to crack propagation are necessary. Also, the restorative procedure with composites are very time-consuming and technically demanding, particularly concerning the application of the adhesive system. Therefore, together with bulk-fill composites, self-adhesive restorative composites could reduce operator error and chairside time. This literature review describes the current stage of development of remineralizing, antibacterial and self-healing composites. Also, an overview of the research on fiber-reinforced composites and self-adhesive composites, both introduced for clinical use in recent years, is presented.

Trends in restorative composites research: what is in the future?

Abstract Clinical trials have identified secondary caries and bulk fracture as the main causes for composite restoration failure. As a measure to avoid frequent reinterventions for restoration replacement, composites with some sort of defense mechanism against biofilm formation and demineralization, as well as materials with lower susceptibility to crack propagation are necessary. Also, the restorative procedure with composites are very time-consuming and technically demanding, particularly concerning the application of the adhesive system. Therefore, together with bulk-fill composites, self-adhesive restorative composites could reduce operator error and chairside time. This literature review describes the current stage of development of remineralizing, antibacterial and self-healing composites. Also, an overview of the research on fiber-reinforced composites and self-adhesive composites, both introduced for clinical use in recent years, is presented.

Fibre reinforcement enhances bonding of soft lining to acrylic dental and maxillofacial prostheses.

This study evaluated shear bond strength between Molloplast-B and different acrylic surfaces; smooth (group1), rough (group2) and Stick net fibre-reinforced interfaces (group 3). Shear tests were conducted with a universal testing machine. Bond failure categories were adhesive, cohesive and mixed failures. Mean bond strengths (SD) in MPa were Group 1, 0.59 (0.08); Group 2, 0.61 (0.08) and Group 3, 0.70 (0.09). There was statistically signiicant difference (p < or = 0.05) between group 3 and group 1 only. Modes of failure were different; mixed and cohesive only exhibited. StickTech Net fibre-reinforced surfaces exhibited stronger bond to Molloplast-B over non-reinforced interfaces, indicating promising clinical implications.

Time-dependence of coronal seal of temporary materials used in endodontics.

The aim of this in vitro study was to compare parametrically the coronal seal ability over different periods of times of four restorative materials used to seal the pulpal access cavity after endodontic treatment. One hundred and thirty-five mandibular premolars were divided randomly into three time groups (1, 2 and 4 weeks), each of which was in turn divided into four subgroups. Each subgroup was restored using one of four restorative materials: Coltosol, glass ionomer cement (GIC), zinc phosphate (ZP) cement, or intermediate restorative material (IRM) cement. The root canals were prepared using the crown-down technique, and obturated using lateral condensation. Following placement of the restorative material, the samples were incubated in distilled water at 37 degrees C and were subjected to 50 thermocycles (0 +/- 4, 56 +/- 4C). After immersing in (2%) methylene blue dye for 24 h, teeth were longitudinally sectioned and examined under a stereomicroscope. The results showed that Coltosol and GIC cement were significantly superior in sealing ability to ZP and IRM cements (P < 0.05). There was no significant difference between GIC cement and Coltosol. Both Coltosol and GIC after 1 week were significantly better than 4 weeks. There was no significant difference in the seal ability at different time periods when ZP and IRM cements were used.

Effect of glass-fiber reinforcement and water storage on fracture toughness (KIC) of polymer-based provisional crown and FPD materials.

PURPOSE: The effect of glass-fiber reinforcement and water storage on the fracture toughness (KIC) of polymer-based provisional crown and fixed partial denture (FPD) materials was investigated. MATERIALS AND METHODS: Five unreinforced single-edged, notched control specimens and five test specimens reinforced with unidirectional E-glass fibers (Stick) were fabricated from three dimethacrylate-based provisional materials and one monomethacrylate-based provisional material. The specimens were stored in water at 37 degrees C for 1, 7, 30, or 60 days. Specimens were loaded in three-point bending at a cross-head speed of 0.1 mm/s. Mode I plane-strain KIC was calculated using the maximum load, and results of the two groups were compared. The water storage effect on KIC with time was also evaluated. RESULTS: The KIC of provisional materials reinforced with glass fibers (range 7.5 to 13.8 MNm(-1.5)) was significantly higher than that of unreinforced materials (range 1.3 to 3.1 MNm(-1.5)), by a factor of 4.4 to 5.5. A small, gradual decrease of KIC in reinforced specimens occurred with aqueous storage, but it was not statistically significant. CONCLUSION: The KIC of polymer-based provisional crown and FPD materials was significantly increased when they were reinforced with unidirectional E-glass fibers. Water storage for up to 2 months still left the reinforced materials with KIC values in excess of 7 MNm(-1.5). Hence, their performance was satisfactory.