Gelatinolytic activity after dentin pretreatment with dimethyl sulfoxide (DMSO) combined to dental bonding systems: Perspectives for biological responses.

Endogeneous proteolytic responses in dentin bonding interface have addressing to strategies to preventive and therapeutic approaches of clinical use of dentin bonding systems (DBSs), but still present limitations. The aim of this study was to examine the gelatinolytic profile by means of in situ zymography regarding the use of 1% dimethyl sulfoxide (DMSO) as an aprotic solvent. Sound human third molars were prepared and randomized in 10 groups, following the factors 1- DBS: Adper™ Scotchbond Multipurpose [MP], Adper™ Single Bond 2 [SB], Clearfil™ SE Bond [CSE] and Adper™ Scotchbond Universal - Etch-and-rinse [SU-ER] mode and self-etch mode [SU-SE], 2- dentin pretreatment: Control - Water [C], 2% CHX and 1% DMSO and 3- time: Initial-24 h [I], 6 months [6M] and 30 months [30M]. Pretreatments were applied before primer application for 30s. After restoration, specimens were cut into slices, in which one third were incubated with fluorescein-conjugated gelatin for 24h at 37 °C and analyzed by confocal laser scanning microscopy. The other two-thirds were stored for 6 or 30 months at 37 °C. Fluorescence was quantified using Image J and data was subjected for two-way ANOVA followed by Tukey test (p<0.05). Neither DMSO nor CHX affected initial analyses for any tested conditions. After 6 months, it was observed increased fluorescence for MP using both pretreatments and for SB using only DMSO. Regardless time and pretreatment, CSE and SU-SE showed stabilized gelatinolytic pattern. For SU-ER, both CHX and DMSO were able to maintain a lower fluorescence compared to control group after 6 months. 30-month performance states the susceptibility of degradation for all etched-dentin systems. DMSO pretreatment can be promising to reduce gelatinolytic activity combined with an universal adhesive system under etch-and-rinse mode. For self-etching strategies, DMSO was successful to stabilize the gelatinolytic reactions.

Performance of MDP-based system in eroded and carious dentin associated with proteolytic inhibitors: 18-Month exploratory study.

The aim of this study was to explore the impact of the interaction between an MDP-based universal adhesive system in etch-and-rinse mode and two proteolytic inhibitors on the longevity of restorations bonded to artificially-affected-dentin substrates. 90 sound human third molars were randomly distributed into three groups according to the substrate: N-no challenges-control (stored in artificial saliva), ACD-artificial caries dentin (6 h DE + 18 h-RE/5 days + 48 h RE) and ERO-artificial erosion dentin (3 × 5 min/5 days with orange juice). They were further redistributed according to dentin pretreatment: W- water (control), CHX-2% digluconate chlorhexidine and E64- 5 µM E64-Trans-Epoxysuccinyl-L-Leucylamido-(4-guanidino) butane, which resulted in the following 9 groups (n = 10): N-W, N-CHX, N-E64, ACD-W, ACD-CHX, ACD-E64, ERO-W, ERO-CHX and ERO-E64. All specimens were restored with Adper Single Bond Universal (Etch-and-rinse mode)/Filtek Z250. Sticks (0.64 mm2) were obtained and subjected to microtensile test (µTBS) in a universal testing machine at 0.5 mm/min for 7-days, 6 and 18-month analyses. Failure modes were classified using optical microscopy (40X). Data were statistically analyzed by three-way ANOVA and Tukey tests (p < 0.05). All individual factors (p < 0.0001) and interaction between factors were statistically significant (substrate X pretreatment (p = 0.00093); substrate X time (p = 0.01035) and pretreatment X time (p = 0.0035). Caries-affected substrate was the most compromised one, disregarding the pretreatment. CHX was mostly affected compared with E64 up to 18 months, possibly due to its calcium-dependent mechanism.

Use of sodium trimetaphosphate in the inhibition of dentin matrix metalloproteinases and as a remineralizing agent.

OBJECTIVES: Because of its ability to act as an antiproteolytic agent, the effect of sodium trimetaphosphate (STMP) against specific enzymes extracted from sound dentin and its performance under acidic challenge on demineralized dentin were investigated. METHODS: The antiproteolytic potential of STMP (0.5%, 1.0%, and 1.5%) was assessed in triplicate by zymography. For the evaluation of remineralization activity, 50 bovine-root dentin specimens were selected and randomly divided into 5 groups (n=10). Three areas were determined for each specimen: 1) control (no treatment); 2) demineralized (artificial caries-like challenge); 3) treated (demineralized and subjected to pH-cycling for 7days, and treated for 10min with 1.5% STMP, 1.5% STMP+calcium hydroxide (Ca[OH]2), 1.5% STMP+sodium fluoride (NaF), NaF, or deionized H2O). The dentin specimens were analyzed for superficial hardness (SH) and cross-sectional hardness (CSH) at different depths (10, 30, 50, 70, 90, 110, and 220µm) using a Knoop penetrator (10g/10s). Statistical analyses were performed with analysis of variance (ANOVA) and Tukey tests (p<0.05). RESULTS: The zymographic analysis showed that 1.5% STMP promoted complete inhibition of gelatinolytic activity. Therefore, 1.5% STMP was investigated in association with supplemented calcium or fluoride; a combination of 1.5% STMP and Ca(OH)2 significantly increased the mechanical properties of the treated dentin. CONCLUSION: 1.5% STMP serves as an antiproteolytic agent against matrix metalloproteinases extracted from human dentin. Furthermore, when supplemented with Ca(OH)2, 1.5% STMP may potentially induce remineralization. CLINICAL SIGNIFICANCE: STMP can be introduced as a novel strategy that combines enzymatic inhibition and remineralizing potential, which can serve to strengthen dentin and improve stability. STMP may have potential in the treatment of demineralized dentin lesions, especially when supplemented with calcium.