M V S Lemos

Efficacy of new natural biomodification agents from Anacardiaceae extracts on dentin collagen cross-linking

OBJECTIVESnSeveral polyphenols from renewable sources were surveyed for dentin biomodification. However, phenols from cashew nut shell liquid (CNSL, Anacardium occidentale) and from Aroeira (Myracrodruon urundeuva) extract have never been evaluated. The present investigation aimed to compare the dentin collagen crosslinking (biomodification) effectiveness of polyphenols from Aroeira stem bark extract, proanthocyanidins (PACs) from grape-seed extract (Vitis vinifera), cardol and cardanol from CNSL after clinically relevant treatment for one minute.nnnMETHODSnThree-point bending test was used to obtain the elastic modulus of fully demineralized dentin beams before and after biomodification, whilst color change and mass variation were evaluated after four weeks water biodegradation. Color aspect was assessed by optical images after biodegradation whereas collagen cross-linking was investigated by micro-Raman spectroscopy. Statistical analysis was performed with repeated-measures two way ANOVA and Tukeys test (p<0.05).nnnRESULTSnThe increase in elastic modulus after biomodification was in the order cardol>cardanol>aroeira=PACs with cardol solution achieving mean 338.2% increase. The mass increase after biomodification followed the same order aforementioned. Nevertheless, after four weeks aging, more hydrophobic agent (cardanol) induced the highest resistance against water biodegradation. Aroeira and cardol attained intermediate outcomes whereas PACs provided the lower resistance. Tannin-based agents (Aroeira and PACs) stained the specimens in dark brown color. No color alteration was observed with cardol and cardanol treatments. All four agents achieved crosslinking in micro-Raman after one minute application.nnnSIGNIFICANCEnIn conclusion, major components of CNSL yield overall best dentin biomodification outcomes when applied for one minute without staining the dentin collagen.

Dentin bonding and physicochemical properties of adhesives incorporated with epigallocatechin-3-gallate

The aim was to assess dentin adhesion and physicochemical properties of experimental etch-and-rinse and self-etch adhesives doped with epigallocatechin-3-gallate (EGCG), a well-known collagen crosslinker obtained from green tea (Camellia sinensis). Experimental adhesives were prepared without (0xa0wt%), with 0.1 or 0.5xa0wt% EGCG addition. Their degree of conversion was surveyed by FTIR, and bar-shaped specimens were tested to obtain flexural strength and modulus initially and after 1-week ethanol storage. Extracted human molars were prepared, bonded, and cut into resin–dentin sticks for microtensile bond strength test, which was conducted after 24xa0h or 6-month water storage. Statistical analyses were performed with two-way ANOVA and Tukey’s test (pu2009<u20090.05). Degree of conversion outcomes depicted a significant polymerization reduction by the addition of EGCG in self-etch adhesive in both concentrations. However, only 0.1% reduced the conversion of etch-and-rinse adhesive. Flexural modulus and strength were significantly diminished (pu2009<u20090.05) by the addition of both concentrations of EGCG for the two model adhesives. Dentin-bond strength was reduced after aging with the addition of EGCG to self-etch adhesive. Nevertheless, 0.5% EGCG increased the bond strength of etch-and-rinse adhesive after aging, conversely to the significant reduction for EGCG-free control adhesive. In conclusion, EGCG at 0.5% provides optimal improvements on dentin bonding without altering final polymerization of a model etch-and-rinse adhesive.