Surface morphology and in vitro leachability of soft liners modified by the incorporation of antifungals for denture stomatitis treatment.

OBJECTIVE: To evaluate the surface morphology and in vitro leachability of temporary soft linings modified by the incorporation of antifungals in minimum inhibitory concentrations (MIC) for Candida albicans biofilm. METHODOLOGY: Specimens of soft lining materials Softone and Trusoft were made without (control) or with the addition of nystatin (Ny), miconazole (Mc), ketoconazole (Ke), chlorhexidine diacetate (Chx), or itraconazole (It) at their MIC for C. albicans biofilm. The surface analyses were performed using Confocal laser scanning microscopy after 24 h, 7 days, or 14 days of immersion in distilled water at 37ºC. In vitro leachability of Chx or Ny from the modified materials was also measured using Ultraviolet visible spectroscopy for up to 14 days of immersion in distilled water at 37ºC. Data (µg/mL) were submitted to ANOVA 1-factor/Bonferroni (α=0.05). RESULTS: Softone had a more irregular surface than Trusoft. Morphological changes were noted in both materials with increasing immersion time, particularly, in those containing drugs. Groups containing Chx and It presented extremely porous and irregular surfaces. Both materials had biexponential release kinetics. Softone leached a higher concentration of the antifungals than Trusoft (p=0.004), and chlorhexidine was released at a higher concentration than nystatin (p<0.001). CONCLUSIONS: The surface of the soft lining materials changed more significantly with the addition of Chx or It. Softone released a higher concentration of drugs than Trusoft did, guiding the future treatment of denture stomatitis.

Cytotoxicity of Etch-and-Rinse, Self-Etch, and Universal Dental Adhesive Systems in Fibroblast Cell Line 3T3.

The aim of this study was to evaluate in fibroblast cultures the direct cytotoxic effects of etch-and-rinse, self-etch, and universal adhesive systems. The sterile glass cover slips (n = 3) were then immersed in culture medium to obtain the eluates for the experimental groups: (1) Adper™ Single Bond 2; (2) Ambar; (3) Adper™ Scotchbond™ Multi-Purpose; (4) Scotchbond™ Universal; (5) Ambar Universal; and (6) OptiBond All-In-One. As a negative control, sterile glass cover slips were immersed in culture medium only. After 24 h, the eluate obtained was applied on fibroblast culture. Cell viability and cell morphology were evaluated by MTT assay and SEM, respectively. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 0.05). All adhesive systems except universal reduced cell viability in 3T3 cells to between 26.04% and 56.57%, and Scotchbond Universal and Ambar Universal reduced cell viability to 2.13% and 3.57%, respectively, when compared to the negative control. Cytoplasmic membrane shrinkage and cell-free areas with residual membrane fragments from dead cells were observed. In conclusion, improvements in universal adhesive system formulations and their mechanisms of action are not accompanied by increased toxicity compared with those in other systems, warranting commitment to the use of these dentin-pulp complexes.

Morphology of root canal surface: A reflection on the process of cementation of the composite relined glass fiber post.

BACKGROUND: The present study was conducted to evaluate the bond strength in the different root thirds (premolars and maxillary central incisors) of composite relined glass fiber posts compared to untreated glass fiber posts cemented with dual- or chemical-cure cements. MATERIALS AND METHODS: Sixty human single-rooted premolars (flat canal) (n = 15) and 12 maxillary central incisors were used (round canal) (n = 3). The teeth were sectioned, and the roots received endodontic treatment. The standardized preparation of the canals was carried out, and the roots were randomly divided into four groups according to the cementation systems: G1: cemented posts (dual: Ambar/Allcem); G2: relined posts (dual: Ambar/Allcem); G3: cemented posts (chemical: Fusion Duralink/Cement Post); and G4: relined posts (chemical: Fusion Duralink/Cement Post). The roots were cut to give two slices of each third of the root canal per specimen. Push-out test was conducted at a speed of 0.5 mm/min. Data were analyzed by analysis of variance and Tukey's post hoc test (α = 0.05). RESULTS: There was no statistically significant difference between groups for the premolars (flat canal) (P = 0.959). There was a significant difference in the central incisors between the middle and apical thirds in the cemented group when using the dual system (P = 0.04) and between the middle and apical thirds (P = 0.003) and cervical and apical thirds (P = 0.033) when using the chemical system. CONCLUSION: Due to the anatomy of the root canal, flat canal of the premolars does not require relining, but round canal of the maxillary central incisors demands it for more secure in the bond strength.

Peel bond strength of soft lining materials with antifungal to a denture base acrylic resin.

The effect of the addition of nystatin, miconazole, ketoconazole, chlorhexidine, and itraconazole into the soft lining materials Softone and Trusoft on their peel bond strength to a denture base acrylic resin was evaluated. Specimens of soft lining materials (n=7) were made without (control) or with the incorporation of antifungals at their minimum inhibitory concentrations to the biofilm of C. albicans and bonded to the acrylic resin. Peel testing was performed after immersion in distilled water at 37ºC for 24 h, 7 and 14 days. Data (MPa) were analyzed by 3-way ANOVA/Tukey-Kramer test (α=0.05) and the failure modes were classified. The addition of nystatin and ketoconazole did not affect the peel bond strength for up to 14 days. Most failures were predominantly cohesive within soft lining materials. With the exception of itraconazole, incorporating the antifungals into the soft lining materials did not result in values below those recommended for peel bond strength after 7 and 14 days of analysis.

Effect of conventional water-bath and experimental microwave polymerization cycles on the flexural properties of denture base acrylic resins.

The effect of polymerization cycles on flexural properties of conventional (Vipi Cril(®)-VC) or microwave-processed (Vipi Wave(®)-VW) denture base acrylic resins was evaluated. Specimens (n=10) were submitted to the cycles: WB=65ºC for 1 h+1 h boiling water (VC cycle); M630/25=10 min at 270 W+5 min at 0 W+10 min at 360 W (VW cycle); M650/5=5 min at 650 W; M700/4=4 min at 700 W; and M550/3=3 min at 550 W. Specimens were submitted to a three-point bending test at 5 mm/min until fracture. Flexural strength (MPa) and elastic modulus (GPa) data were analyzed by 2-way ANOVA/Tukey HSD (α=0.05). Overall, VC showed higher values than VW. The results obtained with microwave polymerization did not differ from those obtained with water-bath for both acrylic resins. The results observed when polymerization cycles using medium power and shorter time were used did not differ from those when manufacturer's recommended microwave cycle was applied. Conventional VC might be microwave-processed without compromising its flexural properties.

An innovative quaternary ammonium methacrylate polymer can provide improved antimicrobial properties for a dental adhesive system.

A quaternary ammonium methacrylate polymer (QAMP) with antimicrobial potential was synthesized. The resulting product (QAMP) was characterized by FTIR spectroscopy, NMR spectroscopy, visible spectrophotometry, XRPD and TGA. The in vitro susceptibility tests against Streptococcus mutans of QAMP were investigated prior and after incorporation into a commercial adhesive system (Clearfil™ SE Bond). The release of quaternary ammonium compounds from the experimental adhesive system (Clearfil™ SE Bond + 5% QAMP) was performed during 1, 7, 14, 21 and 30 days. Spectroscopic data confirmed that QAMP was successfully obtained. Thermogravimetric analysis indicated that QAMP was heat stable. Prior incorporation into the adhesive system, QAMP revealed an inhibition halo of 18.33 ± 0.6 mm. By agar disk diffusion test, Clearfil™ SE Bond containing 5% QAMP presented an inhibition halo (16.67 ± 1.5 mm) similar to Clearfil™ Protect Bond (positive control, 17.00 ± 1.7, p = 0.815) and significantly higher than Clearfil™ SE Bond (negative control, 11.00 ± 1.0, p = 0.006). The minimum inhibitory/bactericidal concentrations for Clearfil™ SE Bond containing 5% QAMP were 20 µL mL(-1). The release of quaternary ammonium compounds from the experimental adhesive containing QAMP was very low (5.1%) when compared to Clearfil™ Protect Bond that released 47.2% of its quaternary ammonium monomer (MDPB) after 30 days. The QAMP can offer enhanced antimicrobial properties for self-etching adhesive systems.

PHBV/PCL microparticles for controlled release of resveratrol: physicochemical characterization, antioxidant potential, and effect on hemolysis of human erythrocytes.

Microparticles of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL) containing resveratrol were successfully prepared by simple emulsion/solvent evaporation. All formulations showed suitable encapsulation efficiency values higher than 80%. PHBV microparticles revealed spherical shape with rough surface and presence of pores. PCL microparticles were spherically shaped with smooth surface. Fourier-transformed infrared spectra demonstrated no chemical bond between resveratrol and polymers. X-ray powder diffraction patterns and differential scanning calorimetry analyses indicated that microencapsulation led to drug amorphization. These PHBV/PCL microparticles delayed the dissolution profile of resveratrol. Release profiles were better fitted to biexponential equation. The hypochlorous-acid-scavenging activity and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation discoloration assay confirmed that the antioxidant activity of PHBV/PCL microparticles was kept, but was dependent on the microparticle morphology and dissolution profile. Resveratrol-loaded PHBV/PCL microparticles showed no cytotoxic effect on red blood cells.

Effect of the regional variability of dentinal substrate and modes of application of adhesive systems on the mechanical properties of the adhesive layer.

AIM: This study assessed the effect of the dentin depth and the application mode on the hardness and elastic modulus of the adhesive layer. MATERIALS AND METHODS: Occlusal surfaces of 48 caries-free human third molars were removed, at two levels: Superficial and deep dentin. For each type of surface, the test specimens were randomly divided into groups which underwent the application: A conventional two-step adhesive system (Adper™ Single Bond [SB]) and self-etch adhesives system (Adper™ SE Plus [SE] and AdheSE(®) [AD]). The adhesives applied were active or passive. Composite build-ups were constructed incrementally. The teeth were sectioned, embedded, and polished. The nanoindentation test was performed in the adhesive layer. The results were analyzed by ANOVA and Tukey tests. RESULTS: In the adhesive layer, the higher hardness (0.307 ± 0.006 GPa) and elastic modulus (4.796 ± 0.165 GPa) of SE were obtained in superficial dentin in passive application. The elastic modulus of SE (4.115 ± 0.098 GPa) was lowest in active application in superficial dentin. The active application significantly increased the hardness of the SB in the deep dentin (0.011 ± 0.314 GPa) compared the superficial dentin (0.280 ± 0.010 GPa). For the AD, only the mode of application was statistically significant (P=0.0041) for the hardness, active application (0.289 ± 0.015 GPa) being higher than passive application (0.261 ± 0.013 GPa) (P=0.0042) in deep dentin. CONCLUSION: The experimental results reveal that the mechanical properties were influenced for the application mode of adhesive systems and dentin depth.

Customized fiber glass posts. Fatigue and fracture resistance.

PURPOSE: To evaluate the root fracture strength of human single-rooted premolars restored with customized fiberglass post-core systems after fatigue simulation. METHODS: 40 human premolars had their crowns cut and the root length was standardized to 13 mm. The teeth were endodontically treated and embedded in acrylic resin. The specimens were distributed into four groups (n=10) according to the restorative material used: prefabricated fiber post (PFP), PFP+accessory fiber posts (PFPa), PFP+unidirectional fiberglass (PFPf), and unidirectional fiberglass customized post (CP). All posts were luted using resin cement and the cores were built up with a resin composite. The samples were stored for 24 hours at 37 degrees C and 100% relative humidity and then submitted to mechanical cycling. The specimens were then compressive-loaded in a universal testing machine at a crosshead speed of 0.5 mm/minute until fracture. The failure patterns were analyzed and classified. Data was submitted to one-way ANOVA and Tukey's test (alpha = 0.05). RESULTS: The mean values of maximum load (N) were: PFP - 811.4 +/- 124.3; PFPa - 729.2 +/- 157.2; PFPf- 747.5 +/- 204.7; CP - 762.4 +/- 110. Statistical differences were not observed among the groups. All groups showed favorable restorable failures. Fiberglass customized post did not show improved fracture resistance or differences in failure patterns when compared to prefabricated glass fiber posts.

Influência do tempo de armazenamento na resistência de união à microtração de diferentes sistemas adesivos em dentina superficial e profunda / Influence of water storage time on microtensile bond strength of different adhesive systems on superficial and deep dentin

O objetivo deste estudo foi avaliar a resistência de união (RU) de um sistema adesivo convencional (Adper™ Single Bond 2 [SB] (3M ESPE, St. Paul, MN, EUA)) e de dois autocondicionantes (Adper™ SE Plus [SE] (3M ESPE, St. Paul, MN, EUA) e AdheSE® [AD] (Ivoclar Vivadent, Schaan, Liechtenstein, DDR)) em dentina superficial (DS) e profunda (DP), nos tempos imediatamente e após 6 meses de armazenamento em água. Superfícies oclusais de 24 terceiros molares humanos foram seccionadas e smear layer padronizada. Após procedimentos adesivos, as superfícies dos dentes receberam restaurações em resina composta. Tais dentes foram seccionados obtendo-se espécimes em forma de palitos (0,7 + 0,1mm2). Os espécimes foram testados por meio do ensaio de microtração (0,5 mm/min), imediatamente e após 6 meses de armazenamento em água. Os dados foram submetidos à ANOVA 3 fatores e ao pós-teste de Bonferroni (α=0,05). Na avaliação imediatamente da RU, apenas o fator “adesivo” foi significativo (p<0,05). Os dados de RU após 6 meses mostraram que a interação dos fatores “adesivo e substrato dentinário” foi significativa (p<0,05). AD em DS (IM: 49,0 ± 6,7 MPa) mostrou diminuição significativa da RU após 6M (23,2 ± 7,9 MPa) de armazenamento em água. SE e AD mostraram diferença significativa (p<0,05) tanto em DS como em DP. Em DS o fator tempo foi significativo e em DP o fator adesivo foi significativo. SB tanto em DS como em DP não apresentou diferença estatisticamente significante imediatamente e após 6 meses (p>0,05). Conclui-se que diferentes níveis de profundidade dentinária podem afetar a RU para o mesmo material e que o fator tempo pode influenciar a degradação do sistema adesivo.

The aim of this study was to evaluate the resin-dentin bond strengths (μTBS) of a total-etch adhesive system (Adper™ Single Bond 2 [SB], 3M ESPE, St. Paul, MN, USA) and of two self-etch adhesive systems (Adper™ SE Plus [SE], 3M ESPE, St. Paul, MN, USA and AdheSE® [AD], Ivoclar Vivadent, Schaan, Liechtenstein, DDR) in superficial dentin (SD) and deep dentine (DD) immediately and after 6 months of storage in water. Surface occlusals of 24 carie-free human third molars were exposed to their SD or DD and polished to create a standardized smear layer. After the adhesive procedures, composite buildups were constructed incrementally and sectioned to obtain bonded sticks (0.7 + 0.1 mm2) that were tested in tension (0.5 mm/min) immediately and after 6 months of water storage. The μTBS data were submitted to a three--way analysis of variance (ANOVA) model with Bonferroni tests (α=0.05). In the evaluation of the immediate μTBS, only the “adhesive” factor was significant (p <0.05). After 6 months of storage in water, the interaction of the “adhesive and dentinal substrate” factors was significant (p<0.05). The AD in SD (IM: 49.0 ± 6.7 MPa) showed a significant decrease in the μTBS after 6 months of storage in water (23.2 ± 7.9 MPa). The SE and AD showed a significant difference (p<0.05) in the SD and DD. The most significant factor for the SD was time, while for the DD, it was the adhesive. The SB in the SD and DD showed no statistically significant differences either immediately or after 6 months (p> 0.05). In conclusion, different levels of dentin depth can affect the bond strength for the same material, and time may influence the degradation of the adhesive system.

Maize (Zea Mays L) landraces from the southern region of Brazil: contamination by Fusarium sp, zearalenone, physical and mechanical characteristics of the kernels

This work had as objectives the study of the physical and mechanical characteristics of maize kernels in relation to the contamination by Fusarium sp and by zearalenone in twenty landraces of maize from the southern region of Brazil. From the analyzed samples, 60 percent has been considered to have a hard endosperm type and 40 percent an intermediary one. A correlation between the physical and mechanical variables was observed as an indication that the higher is the proportion of hard endosperm, more dense will be the kernel and more force for its rupture will be necessary. The level of contamination by Fusarium sp was between 5.5 and 24.75 percent among the analyzed grains, correlating positively with the flotation index, indicating that the landraces of maize with a softer endosperm can present a higher contamination by this genus. The presence of zearalenone was verified in 75 percent of the samples, in concentrations varying from 50 to 640 µg kg-1.

Este trabalho teve por objetivos verificar as características físicas, mecânicas, contaminação por Fusarium sp e por zearalenona e suas relações, em vinte variedades crioulas de milho da região sul do Brasil. Verificou-se que das amostras analisadas, 60 por cento foram consideradas como possuidoras de endosperma do tipo duro e 40 por cento com endosperma do tipo intermediário. As variáveis físicas e mecânicas se correlacionaram, indicando que quanto maior a proporção de endosperma vítreo, mais denso e maior a força necessária até a ruptura do grão. A contaminação por Fusarium sp esteve entre 5,5 por cento e 24,75 por cento nos grãos analisados, correlacionando-se positivamente com o índice de flotação, indicando que as variedades crioulas de milho com uma maior proporção de endosperma macio podem apresentar uma maior contaminação por Fusarium sp, sugerindo-se a utilização de variedades crioulas com a textura do endosperma predominantemente vítrea. A presença de zearalenona foi verificada em 75 por cento das amostras, em concentrações que variaram de 50 a 640 µg kg-1.

Impact of adhesive application and moisture on the mechanical properties of the adhesive interface determined by the nano-indentation technique.

OBJECTIVES: This study assessed the nanohardness (NH) and Young's modulus (YM) of resin-dentin bonding components formed by an ethanol/water-based (Adper Single Bond Plus [SBP]) and an acetone-based system (One Step Plus [OSP]) under different moisture conditions and application methods. MATERIAL AND METHODS: On 24 human molars, a flat, superficial dentin surface was exposed by wet abrasion. After acid-etching, two coats of SBP or OSP adhesive were applied on either a dry or rewetted dentin surface under vigorous rubbing action or inactive application. After polymerization of the adhesives (600 mW/cm2/20 seconds), composite buildups were constructed incrementally and the specimens were stored in water (37 degrees C/24 hours). They were cross-sectioned perpendicular to the resin-dentin interface to obtain 1.5 mm-thick slices that were embedded and polished before the test. Nano-indentations were made on the resin composite, adhesive system, hybrid layer and mineralized dentin. The results of NH and YM (GPa) of the adhesive system and hybrid layer were analyzed using three-way repeated measures ANOVA and Tukey's multiple comparison tests (alpha = 0.05). RESULTS: When the dentin was kept wet, the mode of application did not affect the studied properties within the hybrid layer. On the other hand, the vigorous application mode increased the NH and YM of both adhesives applied in air-dried dentin. In the adhesive layer, the highest NH and YM were observed only for SBP, especially when applied in wet dentin under vigorous action. CONCLUSION: It was concluded that: 1) the vigorous application of both adhesives in dry dentin resulted in high nanohardness and Young's modulus values in the hybrid layer and 2) in the adhesive layer, the moisture associated with the vigorous application mode increased the nanohardness and Young's modulus values of Adper Single Bond Plus.

Active application improves the bonding performance of self-etch adhesives to dentin.

OBJECTIVES: To evaluate the effect of application method on immediate and 6-month resin-dentin microtensile bond strength (microTBS) and nanoleakage (NL) of three one-step self-etch adhesives systems (Clearfil S(3) Bond (S3), Xeno III (XE) and Adper Prompt L-Pop (AD)). METHODS: The oclusal enamel of 30 human molar was removed in order to expose a flat dentin surface. The adhesives were applied under two modes: inactive (IN) or active (AC) application. After light-curing (600mW/cm2 for 10s), composite buildups were constructed incrementally and sectioned to obtain bonded sticks (0.8mm2) to be tested in tension immediately (IM) or after 6 months (6M) of water storage. For NL, three bonded sticks from each tooth at each time were coated with nail varnish, placed in silver nitrate and polished down with SiC paper. The microTBS data were submitted to a two-way ANOVA and Tukey's test for each adhesive (alpha=0.05). RESULTS: The AC showed higher microTBS to dentin when compared to IN in both periods of time (p=0.001). Only for AD, lower microTBS was seen after 6M for IN and AC techniques. XE and S3 adhesives applied under IN showed a higher amount of silver penetration throughout the hybrid layer. Low silver nitrate deposition was seen for these adhesives under AC. After 6M, AD showed a higher amount of silver nitrate uptake under IN and AC techniques. CONCLUSIONS: AC improves the bonding performance of all one-step self-etch adhesive systems tested regardless of the time and this tendency was maintained over time.