RESUMEN

OBJECTIVE: This five-phase, single-blind, crossover in situ trial evaluated the effects of desensitizing or anti-erosive toothpastes on dentin erosive wear and tubule occlusion. MATERIALS AND METHODS: Some characteristics such as relative dentin abrasivity (RDA), viscosity (V), cytotoxicity, and fluoride and calcium (Ca) availability of the toothpastes were also tested. Samples were positioned on removable intraoral appliances from 15 volunteers (n=4), according to the groups, C-control (0 ppm fluoride), F-sodium monofluorophosphate (MFP), A-MFP and arginine+calcium carbonate, CSP-calcium sodium phosphosilicate, and CS-MFP and calcium silicate+sodium phosphate. Erosion-abrasion cycling was performed (1% citric acid, 2min, 6×/day; toothbrushing, 5s, 2×/day). Surface loss (SL) was evaluated by optical profilometry. Environmental scanning electron microscopy images (ESEM) counted the number of open dentin tubules (ODTs). Data were statistically analyzed (α=0.05). RESULTS: There were no significant differences in SL among groups (p=0.468). The ODT for CSP, CS, and A groups were significantly lower than the control. CSP and CS presented significantly less ODT than F, but they did not significantly differ from A. F and CS were more abrasive than all the other toothpastes; CSP was more abrasive than A, and C was the least abrasive. CSP presented higher V (p<0.05). All toothpastes presented lower cell viability than the control without toothpaste exposure. F and A presented significantly higher values of F- (p<0.05). All fluoride toothpastes had similar amount of Ca, differing from the control (p<0.05). CONCLUSION: Although the toothpastes caused similar degree of erosive wear, CSP and CS were able to occlude the dentin tubules. CLINICAL RELEVANCE: Desensitizing toothpastes containing calcium, sodium, phosphate, and silicate could be a suitable option for treating dentin hypersensitivity.

Asunto(s)

Erosión de los Dientes , Desgaste de los Dientes , Fluoruros , Humanos , Silicatos , Método Simple Ciego , Fluoruro de Sodio , Erosión de los Dientes/prevención & control , Cepillado Dental , Pastas de Dientes

RESUMEN

OBJECTIVE: The objective of this study was to evaluate the effect of erosion or erosion-abrasion on bioactive materials and adjacent enamel/dentin areas. METHODS AND MATERIALS: Enamel and dentin blocks (4×4×2 mm) were embedded side by side in acrylic resin, and a standardized cavity (1.2×4×1.5 mm) was prepared between them. Preparations were restored with the following materials: composite resin (Filtek Z350, control); experimental composite containing di-calcium phosphate dihydrate particles (DCPD); Giomer (Beautifil II), high viscosity glass ionomer cement (GIC, Fuji IX); and a resin-modified GIC (Fuji II LC). The specimens were submitted to two cycling models (n=10): erosion or erosion-abrasion. The challenges consisted of five-minute immersion in 0.3% citric acid solution, followed by 60-minute exposure to artificial saliva. Toothbrushing was carried out twice daily, 30 minutes after the first and last exposures to acid. Dental and material surface loss (SL, in µm) were determined by optical profilometry. Data were analyzed with Kruskal-Wallis and Dunn tests (α=0.05). RESULTS: Under erosion, for enamel, only the GIC groups presented lower SL values than Z350 (p<0.001 for Fuji IX and p=0.018 for Fuji II LC). For dentin, none of the materials showed significantly lower SL values than Z350 (p>0.05). For material, the GICs had significantly higher SL values than those of Z350 (p<0.001 for Fuji IX and p=0.002 for Fuji II LC). Under erosion-abrasion, the enamel SL value was significantly lower around Fuji II LC compared with the other materials (p<0.05). No significant differences were observed among groups for dentin SL (p=0.063). The GICs and Giomer showed higher SL values than Z350 (p<0.001 for the GICs and p=0.041 for Giomer). CONCLUSION: Both GIC-based materials were susceptible to erosive wear; however, they promoted the lowest erosive loss of adjacent enamel. Against erosion-abrasion, only Fuji II LC was able to reduce enamel loss. For dentin, none of the materials exhibited a significant protective effect.

Asunto(s)

Esmalte Dental , Cementos de Ionómero Vítreo , Materiales Dentales , Dentina , Saliva Artificial , Cepillado Dental

RESUMEN

OBJECTIVE: The aim of this study was to investigate the influence of the cementation strategy on the fatigue resistance of zirconia crowns. The null hypothesis was that the cementation strategy would not affect the fatigue resistance of the crowns. METHODS AND MATERIALS: Seventy-five simplified molar tooth crown preparations were machined in glass fiber-filled epoxy resin. Zirconia crowns were designed (thickness=0.7 mm), milled by computer-aided design/computer-aided manufacturing, and sintered, as recommended. Crowns were cemented onto the resin preparations using five cementation strategies (n=15): ZP, luting with zinc phosphate cement; PN, luting with Panavia F resin cement; AL, air particle abrasion with alumina particles (125 µm) as the crown inner surface pretreatment + Panavia F; CJ, tribochemical silica coating as crown inner surface pretreatment + Panavia F; and GL, application of a thin layer of porcelain glaze followed by etching with hydrofluoric acid and silanization as crown inner surface pretreatment + Panavia F. Resin cement was activated for 30 seconds for each surface. Specimens were tested until fracture in a stepwise stress fatigue test (10,000 cycles in each step, 600 to 1400 N, frequency of 1.4 Hz). The mode of failure was analyzed by stereomicroscopy and scanning electron microscopy. Data were analyzed by Kaplan-Meier and Mantel-Cox (log rank) tests and a pairwise comparison (p<0.05) and by Weibull analysis. RESULTS: The CJ group had the highest load mean value for failure (1200 N), followed by the PN (1026 N), AL (1026 N), and GL (1013 N) groups, while the ZP group had the lowest mean value (706 N). Adhesively cemented groups (CJ, AL, PN, and GL) needed a higher number of cycles for failure than the group ZP did. The groups' Weibull moduli (CJ=5.9; AL=4.4; GL=3.9; PN=3.7; ZP=2.1) were different, considering the number of cycles for failure data. The predominant mode of failure was a fracture that initiated in the cement/zirconia layer. Finite element analysis showed the different stress distribution for the two models. CONCLUSION: Adhesive cementation of zirconia crowns improves fatigue resistance.

Asunto(s)

Cementación/métodos , Coronas , Diseño de Prótesis Dental , Fracaso de la Restauración Dental , Abrasión Dental por Aire , Diseño Asistido por Computadora , Porcelana Dental , Análisis del Estrés Dental , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Cementos de Resina , Propiedades de Superficie , Cemento de Fosfato de Zinc , Circonio

RESUMEN

This study investigated the effect of nonrinse conditioners (ie, Ketac Nano Primer [KNP] and GC Self Conditioner [SC]) used as substrate pretreatment and their respective paste-paste resin-modified glass-ionomer cement (RMGIC) (ie, Ketac Nano [KN] and Fuji Filling LC [FF]) on microtensile bond strength to dentin and marginal sealing when compared with traditional RMGIC (ie, Photac Fil [PF] and Fuji II LC [FII]) used in association with polyacrylic acid (ie, Ketac Cavity Conditioner [KC] and GC Cavity Conditioner [CC]). A total of 192 extracted human molars were allocated into eight groups: KNP-KN, KC-KN, KNP-PF, KC-PF, SC-FF, CC-FF, SC-FII, and CC-FII. For microtensile bond strength, the teeth were sectioned to expose occlusal dentin and restored according to the group. After 24 hours the teeth were cut to yield nine beams per tooth (±0.8 mm(2)). Testing was done using a universal testing machine followed by failure mode classification. For microleakage testing, standardized cavity preparations were made on the buccal cementoenamel junction and restored according to the group. The teeth were thermocycled (500 cycles, 8°C to 48°C), sealed, immersed in methylene blue for 24 hours, and then assessed for microleakage using a stereomicroscope. Microtensile bond strengths in megapascals (mean±SE) were KNP-KN: 14.9 ± 1.6, KC-KN: 17.2 ± 1.5, KNP-PF: 31.2 ± 1.6, KC-PF: 26.2 ± 1.2, SC-FF: 23.6 ± 1.5, SC-FII: 31.2 ± 1.5, and CC-FII: 21.9 ± 1.5. Cervical margins showed more microleakage compared with occlusal margins. Overall, the use of nonrinse conditioners in association with traditional RMGICs demonstrated superior microtensile bond strengths to dentin when compared with the paste-paste RMGICs. Meanwhile, the association between polyacrylic acid (CC) and a traditional RMGIC (FII) led to the least microleakage for cervical locations when compared with all other groups.

Asunto(s)

Recubrimiento Dental Adhesivo/métodos , Cementos de Ionómero Vítreo/uso terapéutico , Recubrimiento Dental Adhesivo/normas , Filtración Dental/prevención & control , Restauración Dental Permanente/métodos , Análisis del Estrés Dental , Cementos de Ionómero Vítreo/normas , Humanos , Técnicas In Vitro , Diente Molar/cirugía , Resistencia a la Tracción

RESUMEN

The aims of this study were to investigate 1) the influence of cleansing methods after saliva contamination and 2) aging conditions (thermocycling and water storage) on zirconia shear bond strength (SBS) with a resin cement. One hundred and eighty zirconia specimens were sandblasted with 50 µm aluminum oxide particles, immersed in saliva for one minute (with the exception of the control group, [C]), and divided into groups according to the cleansing method, as follows: water rinse (W); 37% phosphoric acid gel (PA); cleaning paste (ie, Ivoclean®) containing mainly zirconium oxide (IC); and 70% isopropanol (AL). Scanning electron microscopy was done to qualitatively evaluate the zirconia surface after each cleansing method. For the SBS test, resin cement buttons were bonded to the specimens using a dedicated jig. SBS was evaluated according to standard protocols after 24 hours, 5000 thermal cycles (TC), or 150 days of water storage. Statistical analysis was performed using two-way analysis of variance and Tukey test (p<0.05). Data showed a significant effect for the 150 days of water storage, TC, and 24 hours of water storage (150 days < TC < 24 hours). Group comparisons showed that PA < AL and W < IC and C. SBS ranged from 10.4 to 21.9 MPa (24 hours), from 6.4 to 14.8 MPa (TC), and from 2.9 to 7.0 MPa (150 days). Failure analysis revealed a greater percentage of mixed failures for the majority of the specimens and a smaller percentage of adhesive failures at the ceramic-resin cement interface. Our findings suggest that Ivoclean® was able to maintain adequate SBS values after TC and 150 days of storage, comparable to the uncontaminated zirconia.

Asunto(s)

Cementos de Resina/metabolismo , Saliva/metabolismo , Itrio/metabolismo , Circonio/metabolismo , Recubrimiento Dental Adhesivo , Análisis del Estrés Dental , Humanos , Microscopía Electrónica de Rastreo , Espectroscopía de Fotoelectrones

RESUMEN

This article presents details of fabrication, biological activity (i.e., anti-matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)-encapsulated halloysite nanotube (HNT)-modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives-but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels-we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via ß-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences (p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of encapsulated MMP inhibitors into the synthesis of therapeutic adhesives that may enhance the longevity of hybrid layers and the overall clinical performance of adhesively bonded resin composite restorations.

Asunto(s)

Antibacterianos/química , Recubrimientos Dentinarios/química , Doxiciclina/química , Nanotubos/química , Silicatos de Aluminio/síntesis química , Silicatos de Aluminio/química , Silicatos de Aluminio/toxicidad , Antibacterianos/síntesis química , Antibacterianos/toxicidad , Caseínas/efectos de los fármacos , Técnicas de Cultivo de Célula , Arcilla , Recubrimiento Dental Adhesivo , Pulpa Dental/citología , Pulpa Dental/efectos de los fármacos , Dentina/efectos de los fármacos , Dentina/ultraestructura , Recubrimientos Dentinarios/síntesis química , Recubrimientos Dentinarios/toxicidad , Doxiciclina/síntesis química , Doxiciclina/toxicidad , Humanos , Ensayo de Materiales , Metaloproteinasa 1 de la Matriz/efectos de los fármacos , Inhibidores de la Metaloproteinasa de la Matriz/química , Nanotubos/toxicidad , Polimerizacion , Cementos de Resina/síntesis química , Cementos de Resina/química , Cementos de Resina/toxicidad , Células Madre/efectos de los fármacos , Streptococcus mutans/efectos de los fármacos , Estrés Mecánico , Resistencia a la Tracción , Factores de Tiempo

RESUMEN

OBJECTIVE: Predisposing factors influencing recurrences of bacterial vaginosis (BV) or vaginitis from Candida remain unidentified for most women. As a component of studies to determine host susceptibility factors to genital tract infections in women, we measured expression of the 60-kDa and 70-kDa heat shock proteins (hsp60 and hsp70, respectively) in the circulation of women with or without a history of recurrent BV or candidal vaginitis and with or without a current lower genital tract infection. Heat shock protein expression is associated with a down-regulation of pro-inflammatory immune responses that would inhibit microbial infection. METHOD: The investigators measured hsp60 and hsp70, antibodies to these proteins, the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), and the anti-inflammatory cytokine interleukin-10 (IL-10) in sera by ELISA. The study population consisted of 100 women who attended a gynecology clinic in Campinas, Brazil. Of those, 55 had a history of recurrent vulvovaginitis (RV), while 45 were controls with no such history. Only women who were asymptomatic for at least 1 month were studied. RESULTS: Although all were asymptomatic, clinical and microbiological examination revealed that five of the women with a history of RV and two controls had a current candidal vaginal infection; 16 RV patients and 12 controls had BV; and six RV patients had both BV and candidiasis. Twenty-eight RV patients and 31 controls had no clinical or microbiological detectable vaginal infection. Among the RV patients, hsp60 and hsp70 were more prevalent in those with current BV (40.9% and 50.0%, respectively) or a candidal infection (45.5% and 54.5%) than in women with no current infection (21.4% and 17.9%). In the women with no history of RV, BV was not associated with a high prevalence of hsp60 (8.3%) or hsp70 (8.3%). Interleukin-10 and TNF were not more prevalent in vaginitis patients or controls with a current candidal infection or BV than in uninfected subjects. CONCLUSION: The high prevalence of circulating hsp60 and hsp70 in women with a history of RV and current BV or vaginal candidiasis, but not in women with no history of RV, suggests that differences in heat shock protein induction may be related to susceptibility to recurrent vaginal infections.

Asunto(s)

Candidiasis Vulvovaginal/inmunología , Chaperonina 60/sangre , Proteínas HSP70 de Choque Térmico/sangre , Vaginosis Bacteriana/inmunología , Adulto , Estudios de Casos y Controles , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Recurrencia

RESUMEN

It was evaluated the Vickers hardness of five high-copper casting alloys, in their original package form and after casting, according to the casting method used. That way, ten ingots, supplied by the manufacturers of each alloy, were included in self-curing acrylic resin, polished, numerated and submitted to Vickers hardness test at load of 200 g during 30 seconds. Afterwards the numerated ingots were removed from the acrylic resin and five of those were cast in an electrical casting machine and the other five in a centrifugal casting machine with an air/gas torch. The specimens obtained were included in self-curing acrylic resin, polished and submitted to Vickers hardness test. As a result it was verified that there is a variation of hardness among the alloys tested, and the use of the electrical casting machine produced lower hardness values than those produced when used the centrifugal casting machine with an air/gas torch. Also, there is a decrease of hardness of the cast alloys when they are tested in their original form and after casting.

Asunto(s)

Aleaciones Dentales , Técnica de Colado Dental , Cobre , Dureza , Pruebas de Dureza