Comprehensive review of current endodontic sealers.

Endodontic sealers for non-surgical root canal treatment (NSRCT) span many compositions and attributes. This comprehensive review discusses current types of endodontic sealers by their setting reaction type, composition, and properties: zinc oxide-eugenol, salicylate, fatty acid, glass ionomer, silicone, epoxy resin, tricalcium silicate, and methacrylate resin sealers. Setting time, solubility, sealing ability, antimicrobial, biocompatibility, and cytotoxicity are all aspects key to the performance of endodontic sealers. Because sealing ability is so important to successful outcomes, the relative degree of microleakage among all the relevant sealers was calculated by way of a meta-analysis of relevant literature. Compared to AH Plus, tricalcium silicate sealers show the lowest relative microleakage among the sealers assessed, followed by silicone sealers and other non-AH Plus epoxy resin sealers. Tricalcium silicate sealers also exhibit the most favorable antimicrobial effect and excellent biocompatibility. Future sealers developed should ideally combine a hermetic seal with therapeutic effects.

Current status of direct pulp-capping materials for permanent teeth.

Direct pulp-capping is a method for treating exposed vital pulp with dental material to facilitate the formation of reparative dentin and to maintain vital pulp. Two types of pulp-capping materials, calcium hydroxide and mineral trioxide aggregate, have been most commonly used in clinics, and an adhesive resin has been considered a promising capping material. However, until now, there has been no comprehensive review of these materials. Therefore, in this paper, the composition, working mechanisms and clinical outcome of these types of pulp-capping materials are reviewed.

Review of methyl methacrylate (MMA)/tributylborane (TBB)-initiated resin adhesive to dentin.

This review, focusing mainly on research related to methyl methacrylate/tributylborane (MMA/TBB) resin, presents the early history of dentin bonding and MMA/TBB adhesive resin, followed by characteristics of resin bonding to dentin. Bond strengths of MMA/TBB adhesive resin to different adherends were discussed and compared with other bonding systems. Factors affecting bond strength (such as conditioners, primers, and medicaments used for dental treatment), bonding mechanism, and polymerization characteristics of MMA/TBB resin were also discussed. This review further reveals the unique adhesion features between MMA/TBB resin and dentin: in addition to monomer diffusion into the demineralized dentin surface, graft polymerization of MMA onto dentin collagen and interfacial initiation of polymerization at the resin-dentin interface provide the key bonding mechanisms.

Dentin permeability reduction by a sequential application of calcium and fluoride-phosphate solutions.

OBJECTIVE: A sequential topical application of calcium and fluoride-phosphate solutions was reported to occlude open dentin tubules, mainly with fluoroapatite precipitates by a rapid ionic reaction, and to be effective at treating dentin hypersensitivity. However, its ability to reduce dentin permeability (Lp) is unknown. The aim of this in vitro study was to evaluate the effect of this treatment on Lp. METHODS: Nine extracted human third molars were sectioned transversely to obtain 0.5 mm-thick discs, which were then etched and rinsed. Aqueous solutions of 5% (w/w) disodium phosphate containing 0.3% (w/w) sodium fluoride (A) and 10% (w/w) calcium chloride (B) were prepared. The sequential application of the A&B solutions was repeated three times on each disc, which was then rinsed with distilled water. The Lp of the discs was measured before and after the application using a modified Pashley's fluid flow measuring system. The differences in the Lp values between the conditions before and after the solution applications were analysed using a generalized estimating equation method and paired t-test. Scanning Electron Microscopy (SEM) was used to observe the dentin surfaces. RESULTS: All nine discs consistently indicated reduced Lp following the application of the A&B solutions. There was a significant decrease in the mean Lp [microL/(cm(2) s cm H(2)O)] from baseline (-0.27+/-0.25, p=0.011). Overall, an average decrease of 34% Lp occurred after the application of the A&B solutions. SEM observation indicated that the reaction products covered the entire dentin disc surface. CONCLUSION: The application of the A&B solutions was effective at reducing the Lp of the dentin discs.

Influence of molecular weight of PMMA in PMMA/MMA-TBB resin on durability of adhesion to titanium against thermal stress in water.

The present study examined the effect of the molecular weight of poly(methyl methacrylate) (PMMA) used in PMMA/ MMA-tributylborane (TBB) resin cement on the durability of adhesion to titanium against repeated thermal stress in water. PMMA beads with the same diameter and molecular weights of 1427, 239, 116, 78, and 66 (x 10(3)) were used. Titanium disks bonded to stainless steel or acrylic rods with the PMMA/MMA-TBB resin were subjected to a thermal cycling test (500 and 2,000 cycles) in water followed by tensile testing. Change in molecular weight of the resin cements collected after thermocycling and tensile testing was examined using size exclusion chromatography (SEC). The acrylic specimens exhibited a significant decrease in post-thermocycling bond strength as compared to the stainless steel specimens. It was also found that the molecular weight of PMMA powder in PMMA/MMA-TBB resin had little influence on adhesion durability to titanium. In terms of the molecular weight of resin cements, they decreased and then increased after 500 and 2,000 cycles respectively.

Polymerization characteristics of ethyl methacrylate-based resin initiated by TBB.

Polymerization characteristics of 4 types of ethyl methacrylate (EMA)-based resin, composed of EMA and EMA/methyl methacrylate (MMA) copolymers and initiated by tributylborane (TBB), were studied from the aspects of long term changes of residual monomer (RM) and molecular weight (Mw). The resins were polymerized at room temperature for 30 min, stored at 37 degrees C for 24 hr, 1 and 4 weeks and then analyzed by high performance liquid chromatography and size exclusion chromatography to determine RM and Mw. RM decreased significantly from 4.47-11.61% after 30 min to 0.94-7.73%, 0.81-7.81%, and 0.78-7.10% after 24 hr, 1 and 4 weeks, respectively, demonstrating a tendency to decrease with time for each resin. Mw showed a tendency to decrease from 427 x 10(3)-551 x 10(3) after 30 min to 354 x 10(3)-530 x 10(3) after 4 weeks. TBB-initiated EMA resin had polymerization characteristics similar to those for TBB-initiated MMA resin in the temporal changes in RM and Mw during postpolymerization.

Properties of a new injectable type of root canal filling resin with adhesiveness to dentin.

The properties of a new, injectable type of root canal wall, adhesive filling resin, which we developed, were studied for its physical properties, adhesiveness to dentin and the root canal, and sealing ability. The new resin consisted of a powder composed of a specially selected poly(methyl methacrylate) and barium sulfate radiopacifier and liquid composed of methyl methacrylate monomer and tributylborane catalyst. A mixture of both components had a consistency suitable for injection. The physical properties, including radiopacity, were evaluated according to the ISO standard. The adhesiveness to dentin and the root canal was investigated by bond strength testing or by scanning electron microscopy. The apical sealing ability of the new resin was compared by a dye penetration test with that of gutta-percha/sealer. The findings of this study indicated that the new filling resin had physical properties satisfying all the ISO requirements for dental root canal sealing materials: a tensile bond strength to dentin of 7.3 MPa, a significantly better sealing ability compared with gutta-percha/sealer, the capability of forming resin tags in dentinal tubules, and removability.

Studies on MMA-tBB resin. I. Comparison of TBB and other initiators in the polymerization of PMMA/MMA resin.

Polymerization characteristics of poly (methyl methacrylate)(PMMA)/(methyl methacrylate) (MMA) resin initiated by tributylborane (TBB) were compared with those by benzoyl peroxide (BPO)/N,N-dimethyl-p-toluidine and camphorquinone (CQ)/N,N-dimethylaminoethyl methacrylate from the aspects of temporal changes of residual MMA and molecular weight up to 4 weeks at 37 degrees C. Residual MMA 30 min after polymerization decreased from 8.15% for TBB resin, 8.39% for the BPO resin, and 9.19% for the CQ resin to 0.48%, 3.54%, and 6.79%, respectively, after 4 weeks. The molecular weights at 30 min and 4 weeks after polymerization were 409 x 10(3) and 247 x 10(3) for TBB resin, 297 x 10(3) and 282 x 10(3) for the BPO resin, and 267 x 10(3) and 231 x 10(3) for the CQ resin, respectively. The present results revealed that the TBB-initiated polymerization had unique and different characteristics compared with those initiated by the other common initiators: (1) The decrease in residual MMA was fast, sustained for a long time and resulted in very low value; (2) high molecular weight PMMA was formed first and then decreased with time.