Influence of addition of 2-[3-(2H-benzotriazol-2-YL)- 4-hydroxyphenyl] ethyl methacrylate to an experimental adhesive system.

The aim of this study was to evaluate the addition of 2-[3-(2HBenzotriazol- 2-yl)-4-hydroxyphenyl]ethyl methacrylate (BTAM) to an experimental adhesive resin. An experimental base adhesive resin was formulated with BisGMA, TEGDMA and HEMA, to which BTAM was added at 1, 2.5 and 5%, in weight. One group with no addition was used as control. The experimental adhesives were evaluated for antibacterial potential (against Streptococcus mutans), degree of conversion with FTIR, softening in solvent and microRaman interface analyses. Data were analyzed by Kruskal-Wallis, paired t test and ANOVA and Tukey, considering a 5% level of significance. The results showed antibacterial activity of 5% BTAM against S. mutans (p<0.05), however, no difference was found among BTAM groups (p> 0.05). The results of degree of conversion and softening of solvent showed no statistical difference between BTAM and control groups (p>0.05). The addition of 5% BTAM showed higher antibacterial activity than the negative control, and copolymerization with comonomer blend of adhesive resin and BTAM was detected at the dentin/ adhesive interface.

Glycerol salicylate-based containing α-tricalcium phosphate as a bioactive root canal sealer.

The use of bioactive materials instead of inert materials to fill the root canal space could be an effective approach to achieve a hermetic seal and stimulate the healing of periapical tissues. The purpose of this study was to develop and characterize an endodontic sealer based on a glycerol salicylate resin and α-tricalcium phosphate (αTCP) at physical and chemical properties. Different sealers were formulated using 70% of a glycerol salicylate resin and 30% of a mixture of calcium hydroxide and αTCP (0, 5, 10, or 15%, in weight). Sealers formulated were characterized based on setting time, in vitro degradation over time, pH, cytotoxicity, and mineral deposition. Sealers presented setting time ranging from 240 to 405 min, and basic pH over 8.21 after 28 days. Higher αTCP concentration leads to sealers with low solubility. Cell viability after 48 h in direct contact with sealers was similar to a commercial sealer used as reference. The 10% and 15% αTCP sealers exhibited a calcium-phosphate layer on the surface after immersion in water and SBF for 7 days. Glycerol salicylate sealers with 10% and 15% α-tricalcium phosphate showed reliable physical-chemical properties and apatite-forming ability.

Oral hygiene caregivers' educational programme improves oral health conditions in institutionalised independent and functional elderly.

OBJECTIVE: The goal of this study was to determine the impact of an oral hygiene education programme for caregivers on the oral health of institutionalised elderly and to examine the effect of disability and low muscle strength on programme outcomes. MATERIALS AND METHODS: The subjects of this study were geriatric patients (n = 80) from a nursing home. Katz Index for activities of daily living, handgrip strength and mucosal-plaque score (MPS) was evaluated at baseline and 1 year after intervention. The intervention consisted of an educational programme and specific guidelines for caregivers (to perform oral hygiene for dependent elderly and to supervise the independent elderly during oral hygiene practices). Differences on MPS were evaluated using a paired-sample t-test. A stratified analysis was carried out to identify differences in response to the programme according to the Katz Index and handgrip strength of elderly. RESULTS: The MPS was significantly reduced (p = 0.001) at follow-up; however, a separate analysis showed that only the independent elderly (p = 0.002) and those with normal muscle strength (p = 0.006) showed a reduction in MPS during the follow-up examination. CONCLUSION: The oral hygiene education programme for caregivers resulted in a positive impact on oral hygiene of the independent and functional elderly.

Polymerization kinetics and reactivity of alternative initiators systems for use in light-activated dental resins.

OBJECTIVES: The purpose of this study was to evaluate the reactivity and polymerization kinetics behavior of a model dental adhesive resin with water-soluble initiator systems. METHODS: A monomer blend based on Bis-GMA, TEGDMA and HEMA was used as a model dental adhesive resin, which was polymerized using a thioxanthone type (QTX) as a photoinitiator. Binary and ternary photoinitiator systems were formulated using 1mol% of each initiator. The co-initiators used in this study were ethyl 4-dimethylaminobenzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), 1,3-diethyl-2-thiobarbituric acid (BARB), p-toluenesulfinic acid and sodium salt hydrate (SULF). Absorption spectra of the initiators were measured using a UV-Vis spectrophotometer, and the photon absorption energy (PAE) was calculated. The binary system camphorquinone (CQ)/amine was used as a reference group (control). Twelve groups were tested in triplicate. Fourier-transform infrared spectroscopy (FTIR) was used to investigate the polymerization reaction during the photoactivation period to obtain the degree of conversion (DC) and maximum polymerization rate (R(p)(max)) profile of the model resin. RESULTS: In the analyzed absorption profiles, the absorption spectrum of QTX is almost entirely localized in the UV region, whereas that of CQ is in the visible range. With respect to binary systems, CQ+EDAB exhibited higher DC and R(p)(max) values. In formulations that contained ternary initiator systems, the group CQ+QTX+EDAB was the only one of the investigated experimental groups that exhibited an R(p)(max) value greater than that of CQ+EDAB. The groups QTX+EDAB+DPIHFP and QTX+DPIHFP+SULF exhibited values similar to those of CQ+EDAB with respect to the final DC; however, they also exhibited lower reactivity. SIGNIFICANCE: Water-soluble initiator systems should be considered as alternatives to the widely used CQ/amine system in dentin adhesive formulations.

Influence of chain extender length of aromatic dimethacrylates on polymer network development.

OBJECTIVE: To investigate the role of chain extender size from Bis-EMA monomers on the polymerization profiles and properties of the crosslinked polymers. Additionally, the influence of Bis-GMA was also evaluated. METHODS: The polymer network from homopolymers Bis-EMA4, Bis-EMA10 and Bis-EMA30 was characterized, as well as copolymers formed among these monomers and Bis-GMA. The degree of conversion from neat and blended monomers as a function of photo-activation time was evaluated by FTIR. Rate of polymerization, network parameter and cross-link density from materials were demonstrated. Water sorption and solubility were determined according to ISO 4049 specification and the data obtained were analyzed by two-way ANOVA/Tukey's test (alpha=0.05). Flexural strength and Young's modulus from polymerized monomers/co-monomers were measured after 24h water storage at 37 degrees C and the results were analyzed by one-way ANOVA/Tukey's test (alpha=0.05). RESULTS: Monomers with larger ethylene oxide units presented the highest values regarding the degree of conversion and cross-link density. The effect of the chain extender length was also observed in water sorption and solubility polymer characteristics, with Bis-EMA4 being the most hydrophobic polymer. Bis-EMA10 and Bis-EMA30 homopolymers were not able to be tested with the three point bending test due to their great flexibility. The addition of Bis-GMA produced stronger and more rigid Bis-EMA polymers (p<0.05). SIGNIFICANCE: Aromatic dimethacrylates with different chain extender lengths can be a useful alternative in controlling the properties of a dental material, adjusting those to specific applications.