Antimicrobial photodynamic therapy against a dual-species cariogenic biofilm using a ruthenium-loaded resin-based dental material.

BACKGROUND: Streptococcus mutans and Candida albicans are associated with caries recurrence. Therefore, this study evaluated the combination of a Ru(II)-loaded resin-based dental material (RDM) and antimicrobial photodynamic therapy (aPDT) against a dual-species biofilm of S. mutans and C. albicans. METHODS: An aPDT protocol was established evaluating Ru(II)'s photocatalytic activity and antimicrobial potential under blue LED irradiation (440-460 nm, 22.55 mW/cm2) at different energy densities (0.00, 6.25, 20.25, 40.50 J/cm2). This evaluation involved singlet oxygen quantification and determination of minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). The biofilm was grown (72 h) on resin disks prepared with Ru(II)-doped RDM (0.00, 0.56, or 1.12 %) and samples were exposed to aPDT or dark conditions. The biofilm was then harvested to analyze cell viability (CFU counts) and formation of soluble and insoluble exopolysaccharides. RESULTS: The photocatalytic activity of Ru(II) was concentration and energy density dependent (p < 0.05), and MIC/MBC values were reduced for the microorganisms after LED irradiation (40.5 J/cm2); therefor, this energy density was chosen for aPDT. Although incorporation of Ru(II) into RDM reduced the biofilm growth compared to Ru(II)-free RDM for both species in dark conditions (p < 0.05), aPDT combined with an Ru(II)-loaded RDM (0.56 or 1.12 %) potentialized CFU reductions (p < 0.05). Conversely, only 1.12 % Ru(II) with LED irradiation showed lower levels of both soluble and insoluble exopolysaccharides compared to Ru(II)-free samples in dark conditions (p < 0.05). CONCLUSIONS: When the Ru(II)-loaded RDM was associated with blue LED, aPDT reduced cell viability and lower soluble and insoluble exopolysaccharides were found in the cariogenic dual-species biofilm.

Calcium silicate-coated porous chitosan scaffold as a cell-free tissue engineering system for direct pulp capping.

OBJECTIVES: This study aimed to develop and characterize different formulations of porous chitosan scaffolds (SCH) associated with calcium silicate (CaSi) and evaluate their chemotactic and bioactive potential on human dental pulp cells (hDPCs). METHODS: Different concentrations of CaSi suspensions (0.5%, 1.0%, and 2.0%, w/v) were incorporated (1:5; v/v) /or not, into 2% chitosan solution, giving rise to the following groups: SCH (control); SCH+ 0.5CaSi; SCH+ 1.0CaSi; SCH+ 2.0 CaSi. The resulting solutions were submitted to thermally induced phase separation followed by freeze-drying procedures to obtain porous scaffolds. The topography, pH, and calcium release kinetics of the scaffolds were assessed. Next, the study evaluated the influence of these scaffolds on cell migration (MG), viability (VB), proliferation (PL), adhesion and spreading (A&S), and on total protein synthesis (TP), alkaline phosphatase (ALP) activity, mineralized matrix deposition (MMD), and gene expression (GE) of odontogenic differentiation markers (ALP, DSPP, and DMP-1). The data were analyzed with ANOVA complemented with the Tukey post-hoc test (α = 5%). RESULTS: Incorporation of the CaSi suspension into the chitosan scaffold formulation increased pore diameter when compared with control. Increased amounts of CaSi in the CH scaffold resulted in higher pH values and Ca release. In Groups SCH+ 1.0CaSi and SCH+ 2.0CaSi, increased VB, PF, A&S, GE of DSPP/DMP-1 and MMD values were shown. However, Group SCH+ 2.0CaSi was the only formulation capable of enhancing MG and showed the highest increase in TP, MMD, and GE of DMP-1 and DSPP values. SIGNIFICANCE: SCH+ 2.0CaSi formulation had the highest chemotactic and bioactive potential on hDPCs and may be considered a potential biomaterial for pulp-dentin complex regeneration.

Exploring the use of a Ruthenium complex incorporated into a methacrylate-based dental material for antimicrobial photodynamic therapy.

OBJECTIVES: To evaluate the effects of a blue light photosensitizer (PS), Ruthenium II complex (Ru), on the chemical, physical, mechanical, and antimicrobial properties of experimental dental resin blends. METHODS: The experimental resin (BisEMA, TEEGDMA, HPMA, ethanol, and photoinitiator) was loaded with Ru at 0.00%, 0.07%, 0.14%, 0.28%, 0.56%, 1.12%, 1.2%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% w/w. Samples were evaluated for the degree of conversion (DC) after 30 and 60 s curing-time (n = 6). Selected formulations (0.00%, 0.28%, 0.56%, 1.12%) were further tested for shear bond strength (SBS) (n = 15); flexural strength (FS) (n = 12); and antimicrobial properties (CFUs), in dark and light conditions. These latter tests were performed on specimens stored for 24-h or 2-month in 37°C water. Water sorption (WS) and solubility (SL) tests were also performed (n = 12). Data were analyzed either by a one- or two-factor general linear model (α = 0.05). RESULTS: Overall, Ru concentration above 1.2% resulted in reduced DC. In SBS results, only the 1.12%Ru resin blend samples had statistically lower values compared to the 0.00%Ru resin blend at 24-h storage (p = 0.004). In addition, no differences in SBS were detected among the experimental groups after 2-month storage in water. Meanwhile, FS increased for all experimental groups under similar aging conditions (p < 0.001). Antimicrobial properties were improved upon inclusion of Ru and application of light (p < 0.001 for both) at 24-h and 2-month storage. Lastly, no detectable changes in WS or SL were observed for the Ru-added resins compared to the 0.00%Ru resin blend. However, the 0.28% Ru blend presented significantly higher WS compared to the 0.56% Ru blend (p = 0.007). CONCLUSIONS: Stable SBS, improved FS, and sustained antimicrobial properties after aging gives significant credence to our approach of adding the Ruthenium II complex into dental adhesive resin blends intended for an aPDT approach.

Effects of curing modes on depth of cure and microtensile bond strength of bulk fill composites to dentin.

Objectives To compare the microtensile bond strength (µTBS) and depth of cure (DOC) of bulk-fill composites cured by monowave (MW) and polywave (PW) LED units using different curing times. Methodology Three composites were tested: Tetric EvoCeram Bulk Fill (TBF), Filtek Bulk Fill (FBF), and Tetric EvoCeram (T; control). Flat dentin surfaces treated with adhesive (AdheSE Universal®, Ivoclar Vivadent) were bonded with 4 mm cylindrical samples of each bulk-fill composite material (n=6) and cured with monowave (Satelec) or polywave (Bluephase Style) curing units for 10 or 20 seconds. After 24 hours, teeth were sectioned into individual 0.9 mm2 beams and tested for µTBS. Failure modes were analysed. Moreover, the DOC scrape test (IOS 4090) was completed (n=5) following the same curing protocols. Two-way ANOVA (a=0.05) was performed, isolating light-curing units. Results For samples cured with the MW light-curing unit, no significant effects were observed in the µTBS results between any of the resin composite brands and the curing times. Conversely, when resins were cured with a PW light unit, a significant effect was observed for TBF resin. In general, bulk-fill composites presented greater DOC and longer curing time resulted in higher DOC for all composites. Conclusion The µTBS of the composites to dentin was not affected by the curing mode of the resins, except for TBF cured with PW light unit. Bulk-fill composites exhibit greater DOC than conventional resin-based composites.

Effects of curing modes on depth of cure and microtensile bond strength of bulk fill composites to dentin

Abstract Objectives To compare the microtensile bond strength (µTBS) and depth of cure (DOC) of bulk-fill composites cured by monowave (MW) and polywave (PW) LED units using different curing times. Methodology Three composites were tested: Tetric EvoCeram Bulk Fill (TBF), Filtek Bulk Fill (FBF), and Tetric EvoCeram (T; control). Flat dentin surfaces treated with adhesive (AdheSE Universal®, Ivoclar Vivadent) were bonded with 4 mm cylindrical samples of each bulk-fill composite material (n=6) and cured with monowave (Satelec) or polywave (Bluephase Style) curing units for 10 or 20 seconds. After 24 hours, teeth were sectioned into individual 0.9 mm2 beams and tested for µTBS. Failure modes were analysed. Moreover, the DOC scrape test (IOS 4090) was completed (n=5) following the same curing protocols. Two-way ANOVA (a=0.05) was performed, isolating light-curing units. Results For samples cured with the MW light-curing unit, no significant effects were observed in the µTBS results between any of the resin composite brands and the curing times. Conversely, when resins were cured with a PW light unit, a significant effect was observed for TBF resin. In general, bulk-fill composites presented greater DOC and longer curing time resulted in higher DOC for all composites. Conclusion The µTBS of the composites to dentin was not affected by the curing mode of the resins, except for TBF cured with PW light unit. Bulk-fill composites exhibit greater DOC than conventional resin-based composites.

Nanocrystalline cellulose as a reinforcing agent for electrospun polyacrylonitrile (PAN) nanofibers.

OBJECTIVES: Nanocrystalline cellulose (NCC) is a sustainable material with excellent mechanical properties and can potentially be used as a reinforcement agent. The objective of this work was to test the effects of NCC incorporation on the mechanical properties of electrospun polyacrylonitrile (PAN) nanofibers. METHODS: Eleven percent in weight of PAN (molecular weight 150 kD) in a dimethylformamide (DMF) solution was electrospun at 14.6 kV. Nonfunctionalized NCC was added to the solution at 1%, 2%, or 3 wt% (NCC/PAN). Suspensions were mixed and sonicated for 2 h before spinning. Strips (5 × 0.5 cm) were cut from the spun mat, parallel and perpendicular to the rotational direction of the fiber collection drum. Tensile tests were performed, and ultimate tensile strength (UTS), yield strength (YS; 0.3%), elastic modulus (E), and elongation at maximum stress (EMS, %) were calculated from stress-strain plots. Data were analyzed by multiple t tests and one-way ANOVA (α = 0.05). RESULTS: Among all groups, samples with 3 wt % NCC loading had significantly superior mechanical properties. The fiber mats showed anisotropic behavior. CONCLUSIONS: Regardless of concentration, the addition of NCC resulted in increased UTS, E, and YS of the nanofibers.

Dentin pretreatment with 45S5 and niobophosphate bioactive glass: Effects on pH, antibacterial, mechanical properties of the interface and microtensile bond strength.

OBJECTIVES: The aim of the study was to evaluate the effect of bioactive glass (45S5 and NbG) suspensions on bond strength (µTBS), hardness, modulus of elasticity, pH and antibacterial activity of the resin-dentin interfaces after 3 months. METHODS: Groups with different concentrations (5% and 20%) of two types of glass (45S5 and NbG), and a control group (distilled water) were studied. Twenty-five extracted human third molars were etched with phosphoric acid. The data from µTBS, hardness and modulus of elasticity data were submitted to two-way ANOVA (suspension vs. time) and Holm-Sidak tests (=0.05). The antimicrobial activity data were analyzed by the Kruskal-Wallis test (α = 5%). RESULTS: The interactions were significant among groups for µTBS (p = 0.033). Significant reductions in µTBS were observed after 3 months storage in PBS for the Control and 5% NbG Groups. Suspensions with 5% and 20% 45S5 glass and 20% NbG resulted in stable µTBS values and increased hardness after 3 months. Both 20% suspensions (45S5 and NbG) increased the elastic modulus. A significant greater reduction in bacterial growth was observed with the use of 20% 45S5. CONCLUSION: Rewetting dentin with the suspension of 20% 45S5 glass prevented the reduction in bond strength; increased hardness; modulus of elasticity of the resin-dentin interface, and demonstrated antibacterial activity against Streptococcus mutans.

Effect of conditioning solutions containing ferric chloride on dentin bond strength and collagen degradation.

OBJECTIVE: To investigate the effects of conditioning solutions containing ferric chloride (FeCl3) on resin-dentin bond strength; on protection of dentin collagen against enzymatic degradation and on cathepsin-K (CT-K) activity. METHODS: Conditioning solutions were prepared combining citric acid (CA) and anhydrous ferric chloride (FeCl3) in different concentrations. The solutions were applied to etch flat dentin surfaces followed by bonding with adhesive resin. Phosphoric acid (PA) gel etchant was used as control. The microtensile bond strength (µTBS) was tested after 24h of storage in water and after 9 months of storage in phosphate buffer saline. Dentin slabs were demineralized in 0.5M EDTA, pre-treated or not with FeCl3 and incubated with CT-K. The collagenase activity on dentin collagen matrix was examined and characterized by SEM. Additional demineralized dentin slabs were treated with the conditioning solutions, and the amount of Fe bound to collagen was determined by EDX. The activity of CT-K in the presence of FeCl3 was monitored fluorimetrically. Data were analyzed by ANOVA followed by post-hoc tests as required (α=5%). RESULTS: Slightly higher bond strengths were obtained when dentin was conditioned with 5% CA/0.6% FeCl3 and 5% CA-1.8%FeCl3 regardless of storage time. Bond strengths reduced significantly for all tested conditioners after 9 months of storage. Treating dentin with 1.8% FeCl3 was effective to preserve the structure of collagen against CT-K. EDX analysis revealed binding of Fe-ions to dentin collagen after 15s immersion of demineralized dentin slabs into FeCl3 solutions. FeCl3 at concentration of 0.08% was able to suppress CT-K activity. SIGNIFICANCE: This study shows that FeCl3 binds to collagen and offers protection against Cat-K degradation. Mixed solutions of CA and FeCl3 may be used as alternative to PA to etch dentin in resin-dentin bonding with the benefits of preventing collagen degradation.

Can 1% chlorhexidine diacetate and ethanol stabilize resin-dentin bonds?

OBJECTIVES: To examine the effects of the combined use of chlorhexidine and ethanol on the durability of resin-dentin bonds. METHODS: Forty-eight flat dentin surfaces were etched (32% phosphoric acid), rinsed (15 s) and kept wet until bonding procedures. Dentin surfaces were blot-dried with absorbent paper and re-wetted with water (water, control), 1% chlorhexidine diacetate in water (CHD/water), 100% ethanol (ethanol), or 1% chlorhexidine diacetate in ethanol (CHD/ethanol) solutions for 30 s. They were then bonded with All Bond 3 (AB3, Bisco) or Excite (EX, Ivoclar-Vivadent) using a smooth, continuous rubbing application (10 s), followed by 15 s gentle air stream to evaporate solvents. The adhesives were light-cured (20 s) and resin composite build-ups constructed for the microtensile method. Bonded beams were obtained and tested after 24-h, 6-months and 15-months of water storage at 37°C. Storage water was changed every month. Effects of treatment and testing periods were analyzed (ANOVA, Holm-Sidak, p<0.05) for each adhesive. RESULTS: There were no interactions between factors for both etch-and-rinse adhesives. AB3 was significantly affected only by storage (p=0.003). Excite was significantly affected only by treatments (p=0.048). AB3 treated either with ethanol or CHD/ethanol resulted in reduced bond strengths after 15 months. The use of CHD/ethanol resulted in higher bond strengths values for Excite. CONCLUSIONS: Combined use of ethanol/1% chlorhexidine diacetate did not stabilize bond strengths after 15 months.

Microtensile bond strengths for six 2-step and two 1-step self-etch adhesive systems to enamel and dentin.

PURPOSE: To examine the microtensile bond strengths (microTBS) of six 1-step and one 2-step self-etch systems to dentin and ground enamel. METHODS: Resin composite buildups were bonded to buccal and lingual ground enamel surfaces, and to occlusal dentin of third molars using the following 1-step adhesives: Xeno IV (XE), GBond (GB), Clearfil S3 Bond (CS3); Adper Prompt L-Pop (AD); Go (GO) and All Bond SE (1-step; ABSE), in comparison to the 2-steps (All Bond SE; (2-step ABSE) and Clearfil SE Bond (CSE). After storage in water (24 hour/37 degrees C), the bonded specimens were sectioned into beams approximately 0.9 mm2. These beams were tested until failure at a crosshead speed of 0.5 mm/minute. Data were subjected to appropriate statistical analysis (alpha = 0.05). RESULTS: The total number of specimens/premature debonding specimens (PDS) for each adhesive were, respectively, in enamel: XE (59/36), GB (63/33), CS3 (62/29), AD (47/19), GO (53/14), 1-step ABSE (61/29), 2-step ABSE (57/14) and CSE (58/13); and in dentin: XE (51/24), GB (50/7), CS3 (53/13), ADP (51/1), GO (43/8), 1-step ABSE (59/2), 1-step ABSE (56/0) and CSE (47/0). The fracture pattern was predominantly adhesive/mixture for all adhesives in dentin (51.5 to 99%) and in enamel (34.8 to 75.4%), however XE (61.2) and GB (52.5) had more than 50% PDS. For ground enamel, no significant difference was detected among materials in the same subgroup (with or without PDS). However, there was a significant difference for all adhesives when subgroups (with and without PDS, respectively) were tested against each other: XE (7.9/10.5 double dagger 19.7/5.5), GB (8.6/10.5 double dagger 17.2/7.4), CS3 (8.8/10.3 double dagger 15.7/5.6), AD (13.0/12.0 = 20.3/8.9), Go (18.2/13.8 = 25.1/10.0), 1-step ABSE (15.9/11.4 = 16.2/5.4), 2-step ABSE (8.4/9.1 double dagger 25.3/7.9) and CSE (17.6/16.3 = 19.9/7.8). For dentin, no difference was found when subgroups for the same adhesive were tested against each other (with or without PDS). However, significantly higher resin-dentin bond strength was observed for adhesives in the following order: CSE (38.5/6.5 = 38.5/6.5) > or = 2-step ABSE (41.4/16.3 double dagger 42.4/19.3) = 1-step ABSE (43.9/17.7 = 44.2/17.1) = AD (34.4/14.2 = 35.2/13.3) < or = CS3 (31.9/19.4 = 40.1/13.4) double dagger GB (14.3/6.3 = 16.3/5.9) = Go (14.2/13.9 = 22.4/12.6) double dagger XE (7.1/5.4 = 9.5/5.1), respectively for with PDS and without PDS. All materials showed similar performance on ground enamel. The performance of one-step self-etch systems to dentin appears to be material-dependent. Adper Prompt L-Pop, Clearfil S3 Bond and the 1-step All Bond SE had microTBS similar to Clearfil SE Bond and the 2-step All Bond SE, while Xeno IV and GBond had significantly lower microTBS values. Go had an intermediate performance.

Water interaction with dental luting cements by means of sorption and solubility / Interação da água com cimentos dentais de acordo com a sorção e solubilidade

Water contributes to the setting reaction of self-adhesive luting cements, however, it can also accelerate their degradation. Objectives: The aim of this study was to compare a self-adhesive resin luting cement to other resin-based and glass-ionomer luting materials with regards to water sorption (WS) and solubility (WSB). The tested null hypothesis was that there is no difference in respect to these properties among the materials. Material and methods: Eight specimens from each group (15 mm x 0.5 mm) were prepared from self-adhesive luting cements Biscem (BC) and RelyX Unicem (R), dual-cure cements Bifix (BF), Allcem (A) and Enforce (E), chemical-cure cements C&B (CB) and Cement Post (CP) and a glass-ionomer luting cement Meron C (M) as the control group. The dual-cure products were light-cured beneath an IPS Empress Esthetic ceramic disk (20 mm x 1.5 mm) and for the chemical reaction materials, a 15 min-interval was respected for removal from the mould. The WS and WSB were respectively calculated as (m2-m3/V) and (m1-m3/V). Mass values of m1, m2 and m3 were determined by cycles of desiccation, water-immersion and a new desiccation. For each property, the data was analyzed by one-criteria ANOVA and Tukey tests (p < 0.05). Results: The glass-ionomer cement presented the highest WS, followed by the self-adhesive luting cements. Other resin cements were less susceptible to WS. No materials differed from each other when the WSB was considered, except for the M, which presented the lowest WSB. Conclusions: Self-adhesive luting cements were more prone to WS since water is essential to their setting reaction. However, their WSB was similar to the other resin-based cements.

A água contribui para a reação de presa dos cimentos auto adesivos, entretanto pode acelerar a sua degradação. Objetivos: O objetivo deste estudo foi comparar cimentos auto adesivos a outros cimentos resinosos e material ionomérico em relação à sorção de água (WS) e solubilidade (WSB). A hipótese nula foi de que não há diferença em relação a essas propriedades entre os materiais. Material e métodos: Oito espécimes de cada grupo (15 mm x 0,5 mm) foram preparados dos cimentos auto adesivos Biscem (BC) e RelyX Unicem (R), cimentos duais Bifix (BF), Allcem (A) e Enforce (E), cimentos químicos C&B (CB) e Cement Post (CP) e um cimento ionomérico Meron C (M) como grupo controle. Os produtos duais foram fotoativados sob um disco cerâmico de IPS Empress Esthetic (20 mm x 1,5 mm) e para os materiais de reação química, um intervalo de 15 min foi respeitado para a remoção do molde. A WS e WSB foram respectivamente calculadas como (m2-m3/V) e (m1-m3/V). Valores de massa m1, m2 and m3 foram determinadas pelos ciclos de dessecação, imersão em água e nova dessecação. Para cada propriedade, os dados foram analisados pelos testes de ANOVA a um critério e Tukey (p < 0.05). Resultados: O cimento ionomérico apresentou a maior WS, seguido dos cimentos auto adesivos. Os demais cimentos resinosos foram menos suscetíveis a WS. Nenhum material diferiu do outro quanto a WSB foi considerada, exceto por M, que apresentou a menor WSB. Conclusões: Cimentos auto adesivos foram mais suscetíveis a WS, uma vez que a água é essencial para sua reação de presa. Entretanto, seu WSB foi similar aos demais cimentos resinosos.

Effect of an additional hydrophilic versus hydrophobic coat on the quality of dentinal sealing provided by two-step etchand-rinse adhesives

OBJECTIVE: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. MATERIAL AND METHODS: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. RESULTS: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. CONCLUSIONS: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent.

Effect of an additional hydrophilic versus hydrophobic coat on the quality of dentinal sealing provided by two-step etch-and-rinse adhesives.

OBJECTIVE: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. MATERIAL AND METHODS: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. RESULTS: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. CONCLUSIONS: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent.

Avaliação da associação de clorexidina com etanol nadurabilidade da adesão à dentina / Evaluation of the adjunctive use of chlorhexidine and ethanol on the durability of resin dentin bonds

A degradação do adesivo e colágeno é considerada uma das principaiscausas de falhas nos processos adesivos à dentina. A completa infiltraçãode resinas hidrofóbas facilitada pelo etanol, associada à presença deinibidores de metaloproteinases presentes na dentina, poderia construir aunião ideal, resistente à hidrólise e atividades enzimáticas. Este estudoexaminou os benefícios do uso combinado de clorexidina como inibidor demetaloproteinases e etanol, na durabilidade de uniões resina-dentina.Foram utilizados 48 terceiros molares hígidos para obter superfícies planasde dentina que foram condicionadas com ácido fosfórico a 32% por 15segundos, lavadas por 30 segundos, e secas com papel absorvente.Imediatamente após, uma das seguintes soluções foi aplicada por 30segundos: água (A); etanol (E); solução aquosa de clorexidina a 1% (CA);solução alcoólica de clorexidina a 1% (CE). O excesso foi removido compapel absorvente e um dos adesivos, All Bond 3 (AB3) ou Excite (EX), foiaplicado à superfície sob agitação por 15 segundos, seguido por um jatode ar por igual tempo, e fotoativado por 20 segundos. Uma coroa deaproximadamente 4 mm foi construída incrementalmente em resinacomposta e os dentes foram armazenados por 24 horas em água destiladaà 370C. A seguir foram cortados em paralelogramos para o teste demicrotração. Um terço dos corpos de prova foi ensaiado imediatamente eos demais permaneceram armazenados por 6 ou 15 meses. Os efeitos dostratamentos e períodos de armazenagem foram analisados para cadaadesivo. Os resultados não demonstraram interação entre os fatores paraambos os adesivos.

AB3 foi significantemente afetado pela armazenagem,mas não pelos tratamentos. EX foi significantemente afetado pelotratamento, mas não pela armazenagem. Concluiu-se que o uso declorexidina/etanol não melhorou a estabilidade da união após 15 meses.AB3 quando tratado com A ou CA, e EX com todos os tratamentos nãoforam afetados pela armazenagem.

Both adhesive and collagen degradation have been regarded as majorcauses of resin-dentin bonds failures over time. Complete infiltration ofhydrophobic resins facilitated by ethanol, and the presence of MMPs’inhibitors within the hybrid layer would build the ideal interface, resistantto hydrolysis and enzymatic activities. This study examined the benefits ofthe adjunctive use of chlorhexidine and ethanol on the durability of resindentin bonds. Forty-eight flat dentin surfaces were etched (32%phosphoric acid), rinsed (30s) and blot-dried with absorbent paper. Thesurfaces were re-wetted with either water (Water); 1% chlorhexidinediacetate in water (CHX/Water); 100% ethanol (Ethanol); and 1%chlorhexidine diacetate in ethanol (CHX/Ethanol) solutions for 30s. Theywere then bonded with All Bond 3 (AB3, Bisco) or Excite (EX, Ivoclar-Vivadent) using a smooth, continuous rubbing application (15s), followedby 15s gentle air dry. The adhesives were light-cured (20s) and resinbuild-ups constructed incrementally for the microtensile method. Bondedbeams were obtained and tested after 24-hours, 6-months, and 15-months water storage at 370C. Effects of treatment and testing periodswere analyzed (ANOVA, Holm-Sidak, p<0.05) for each adhesive. Therewere no interactions between factors for both adhesives. AB3 wassignificantly affected by storage, but not by treatments. Excite wassignificantly affected by treatments, but not by storage. Adjunctive use ofethanol/chlorhexidine did not improve bond stability after 15 months. AB3treated either with ethanol or CHX/ethanol resulted in reduced bondstrengths after 15 months. AB3 treated with water or CHX/water and alltreatments for Excite were not affected by storage.

Effects of a combined application of potassium oxalate gel/adhesive agent on dentin permeability in vitro.

PURPOSE: To test the effects of sequential application of potassium oxalate gel/adhesive agent on in vitro dentin permeability. MATERIALS AND METHODS: Full crown preparations were made in extracted human molars to expose deep coronal dentin. The roots and pulp were removed and the resulting crown segments were connected to a special device (Flodec) to permit the measurement of the permeability of the specimens before and after treatments. Minimum and maximum permeability were recorded after smear layer and phosphoric acid treatment. A new smear layer was created and the permeability measured after the crowns were bonded with Single Bond (3M ESPE), One-Up Bond F (Tokuyama), and AdheSE (Ivoclar Vivadent), either according to manufacturer's instructions or after treating the acid-etched dentin with a 3 wt% potassium oxalate gel. The results were expressed as a percentage of maximum permeability values. Impressions and epoxy resin replicas from the crown segments were produced for SEM examination. RESULTS: None of the adhesives were able to eliminate the fluid flow through dentin. Two-way ANOVA revealed that the application of potassium oxalate prior to the bonding procedures was the most effective technique in reducingthe dentin permeability (p < 0.05), regardless of the adhesive used. SEM micrographs showed that transudation of dentinal fluid could be identified on the surfaces of all replicas. CONCLUSION: The use of potassium oxalate gel was effective in reducing the permeability of bonded dentin.

Resinas compostas posteriores: análise de longevidade e comportamento clínico / Posterior composite restorations: analysis of longevity and clinical performance

A proposta deste estudo foi determinar como as resinas compostas inseridas em dentes posteriores têm se comportado clinicamente. A influência de fatores como higiene oral e risco à cárie, tamanho e localização da cavidade a ser restaurada, características físico-químicas das resinas compostas e a técnica operatória foram analisadas. As principais causas de falhas que determinam a substituição da restauração são a infiltração marginal e o desgaste. os critérios e o bom senso clínico para indicar uma restauração de resina composta em dentes posteriores são de importância fundamental para que elas tenham razoável longevidade. A otimização de resultados a longo prazo depende diretamente da análise crítica do profisional frente à cada situação clínica e dos cuidados com a técnica restauradora que ele emprega