Tooth structure and fracture strength of cavities.

This study evaluated, in vitro, the loss of tooth substance after cavity preparation for direct and indirect restorations and its relationship with fracture strength of the prepared teeth. Sixty sound human maxillary first premolars were assigned to 6 groups (n=10). MOD direct composite cavities (Groups I, II and III) and indirect inlay cavities (Groups IV, V and VI) were prepared maintaining standardized dimensions: 2-mm deep pulpal floors, 1.5-mm wide gingival walls and 2-mm high axial walls. Buccolingual width of the occlusal box was established at 1/4 (Groups I and IV), 1/3 (Groups II and V) or 1/2 (Groups III and VI) of the intercuspal distance. Teeth were weighed (digital balance accurate to 0.001 g) before and after preparation to record tooth substance mass lost during cavity preparation. The prepared teeth were submitted to occlusal loading to determine their fracture strength using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (alpha= 0.05). 1/4-inlay cavities had higher percent mean mass loss (9.71%) than composite resin cavities with the same width (7.07%). 1/3-inlay preparations also produced higher percent mean mass loss (13.91%) than composite resin preparations with the same width (10.02%). 1/2-inlay cavities had 21.34% of mass loss versus 16.19% for the 1/2-composite resin cavities. Fracture strength means (in kgf) were: GI = 187.65; GII = 143.62; GIII = 74.10; GIV = 164.22; GV = 101.92; GVI = 50.35. Statistically significant difference (p<0.05) were observed between Groups I and IV, II and V, III and VI. Higher tooth structure loss and lower fracture strength were recorded after preparation of inlay cavities, regardless of the width of the occlusal box, compared to the direct composite resin cavities.

Microhardness of composite resins at different depths varying the post-irradiation time

OBJECTIVE: The purpose of this study was to assess the microhardness of posterior composite resins at different depths varying the post-irradiation time. MATERIALS AND METHODS: For each composite resin [Solitaire 2 (SO) - Heraus Kulzer, P60 (P) - 3M, Prodigy Condesable (PC) - Kerr, Surefil (S) - Dentsply and Alert (A) - Pentron], 6 specimens (3 mm in diameter; 4mm high) were prepared using a black polyurethane cylindrical matrix. The resins were inserted in a bulk increment and light cured for 40 seconds. Microhardness was analyzed at different depths (top, 0.4 mm, 1.0 mm, 2.0mm, 3.0 mm and 4.0 mm) and at two moments (20 minutes and 24 hours after light-curing). Data were analyzed by ANOVA and Tukey's test (p<0.05). RESULTS: Overall, microhardness means decreased significantly with the increase of depth, being lower in the first moment tested. P, S and PC showed the highest microhardness means. CONCLUSION: It may be concluded that the tested composite resins presented a gradual decrease of microhardness as depth increased and this drop was more accentuated for depths beyond 2 mm. For all materials, higher microhardness means were recorded 24 hours after light activation. P60 yielded the best results at the different depths evaluated.

Microhardness of composite resins at different depths varying the post-irradiation time.

OBJECTIVE: The purpose of this study was to assess the microhardness of posterior composite resins at different depths varying the post-irradiation time. MATERIALS AND METHODS: For each composite resin [Solitaire 2 (SO) - Heraus Kulzer, P60 (P) - 3M, Prodigy Condesable (PC) - Kerr, Surefil (S) - Dentsply and Alert (A) - Pentron], 6 specimens (3 mm in diameter; 4 mm high) were prepared using a black polyurethane cylindrical matrix. The resins were inserted in a bulk increment and light cured for 40 seconds. Microhardness was analyzed at different depths (top, 0.4 mm, 1.0 mm, 2.0 mm, 3.0 mm and 4.0 mm) and at two moments (20 minutes and 24 hours after light-curing). Data were analyzed by ANOVA and Tukey's test (p<0.05). RESULTS: Overall, microhardness means decreased significantly with the increase of depth, being lower in the first moment tested. P, S and PC showed the highest microhardness means. CONCLUSION: It may be concluded that the tested composite resins presented a gradual decrease of microhardness as depth increased and this drop was more accentuated for depths beyond 2 mm. For all materials, higher microhardness means were recorded 24 hours after light activation. P60 yielded the best results at the different depths evaluated.

Tooth structure and fracture strength of cavities

This study evaluated, in vitro, the loss of tooth substance after cavity preparation for direct and indirect restorations and its relationship with fracture strength of the prepared teeth. Sixty sound human maxillary first premolars were assigned to 6 groups (n=10). MOD direct composite cavities (Groups I, II and III) and indirect inlay cavities (Groups IV, V and VI) were prepared maintaining standardized dimensions: 2-mm deep pulpal floors, 1.5-mm wide gingival walls and 2-mm high axial walls. Buccolingual width of the occlusal box was established at 1/4 (Groups I and IV), 1/3 (Groups II and V) or 1/2 (Groups III and VI) of the intercuspal distance. Teeth were weighed (digital balance accurate to 0.001 g) before and after preparation to record tooth substance mass lost during cavity preparation. The prepared teeth were submitted to occlusal loading to determine their fracture strength using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (alpha= 0.05). 1/4-inlay cavities had higher percent mean mass loss (9.71 percent) than composite resin cavities with the same width (7.07 percent). 1/3-inlay preparations also produced higher percent mean mass loss (13.91 percent) than composite resin preparations with the same width (10.02 percent). 1/2-inlay cavities had 21.34 percent of mass loss versus 16.19 percent for the 1/2-composite resin cavities. Fracture strength means (in kgf) were: GI = 187.65; GII = 143.62; GIII = 74.10; GIV = 164.22; GV = 101.92; GVI = 50.35. Statistically significant difference (p<0.05) were observed between Groups I and IV, II and V, III and VI. Higher tooth structure loss and lower fracture strength were recorded after preparation of inlay cavities, regardless of the width of the occlusal box, compared to the direct composite resin cavities.

O objetivo deste estudo foi avaliar, in vitro, a perda de estrutura dentária após o preparo cavitário para restaurações diretas e indiretas e sua relação com a resistência à fratura do dente. 60 pré-molares superiores humanos foram divididos em 6 grupos (n=10). Cavidades MOD para resina composta direta (Grupos I, II e III) e cavidades "inlay" (Grupos IV, V e VI) foram preparadas mantendo dimensões padronizadas. A extensão vestíbulo-lingual da caixa oclusal foi estabelecida em 1/4 (Grupos I e IV), 1/3 (Grupos II e V) ou 1/2 (Grupos III e VI) da distância intercuspídea. Os dentes foram pesados, em uma balança de precisão, antes e após o preparo cavitário para aferir a perda de massa dentária. Os dentes preparados foram submetidos à força de compressão para determinar a resistência à fratura em uma máquina universal de ensaios sob uma velocidade de 0.5 mm/min. Os dados foram submetidos à análise de variância a dois critérios e ao teste de Tukey (alfa = 0.05). As cavidades do tipo "1/4-inlay" apresentaram maior percentual de perda de massa (9.71 por cento) em relação às cavidades para resina composta com mesma extensão (7.07 por cento). As cavidades do tipo "1/3-inlay" também apresentaram maior percentual de perda de massa (13.91 por cento) quando comparada às cavidades para resina composta com a mesma extensão (10.02 por cento). As cavidades do tipo "1/2-inlay" apresentaram 21.34 por cento de perda de massa, enquanto as cavidades com extensão de 1/2 para resina composta apresentaram uma perda de 16.19 por cento. As médias de resistência à fratura (em kgf) foram: GI = 187.65; GII = 143.62; GIII = 74.10; GIV = 164.22; GV = 101.92; GVI = 50.35. Diferenças estatisticamente significantes (p<0.5) foram observadas entre os Grupos I e IV, II e V, III e VI. Maior perda de estrutura dentária e menor resistência à fratura foram verificadas após os preparos do tipo "inlay" quando comparados aos preparos para resina composta direta.

Comparison of marginal microleakage of flowable composite restorations in primary molars prepared by high-speed carbide bur, Er:YAG laser, and air abrasion.

PURPOSE: The purpose of this study was to assess in vitro the influence of 3 cavity preparation devices (carbide bur, Er:YAG laser, and air abrasion) on the microleakage of flowable composite restorations in primary teeth. METHODS: Fifteen primary second molars were selected, and Class V cavities were prepared on the buccal/lingual surfaces, being assigned to 3 groups (n= 10). Group 1 (control) was prepared using a high-speed handpiece and was acid etched. Group 2 was prepared and treated with a Er:YAG laser (400mJ/4Hz and 80mJ/4Hz, respectively) and was acid etched. Group 3 was prepared and treated with an air abrasion system and was acid etched. Cavities were restored and stored for 7 days. Restorations were polished, thermocycled, immersed in 0.2% rhodamine B, sectioned, and analyzed for leakage. RESULTS: Er:YAG laser-prepared cavities showed the highest degree of infiltration. The performance of the air abrasion device was comparable to that of the high-speed handpiece. CONCLUSION: It may be concluded that the method of cavity preparation affected the microleakage of Class V cavities restored with flowable composite in primary teeth.

Evaluation of the surface hardness of composite resins before and after polishing at different times

PURPOSE: The aim of this study was to evaluate the surface hardness of six composite resins: Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables), Silux Plus (microfilled) and Z100 (minifilled) before and after polishing at different times. MATERIALS AND METHODS: For this purpose, 240 specimens (5mm diameter, 1.4mm high) were prepared. Vickers hardness was determined before and after polishing at different times: immediately, 24h, 7 and 21 days after preparation of the samples. Statistical analysis was performed by ANOVA and Tukey test. RESULTS: There was no difference in the hardness of flowable resins, which had lower hardness than the minifilled resin. The minifilled resin showed the highest surface hardness as compared to the other materials (p<0.01). All materials exhibited higher hardness after polishing, being more evident after 7 days. CONCLUSION: It may be concluded that, regardless of the composite resin, surface hardness was considerably increased when polishing was delayed and performed 1 week after preparation of the samples.

PROPOSIÇÃO: O objetivo deste estudo foi avaliar a dureza superficial de seis resinas compostas - Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables), Silux Plus (micropartículas) e Z100 (híbrida) - antes e após o polimento realizado em diferentes tempos. MATERIAL E MÉTODO: Foram confeccionados 240 corpos-de-prova circulares (5mm de diâmetro e 1,4mm de altura). A dureza Vickers foi obtida antes e após o polimento realizado em diferentes tempos: imediatamente, 24 horas, 7 dias e 21 dias após a confecção do corpo-de-prova. Os dados foram analisados estatisticamente por meio da ANOVA e do Teste de Tukey. RESULTADOS: Não houve diferença entre as resinas compostas flowable, as quais apresentaram os menores valores de dureza. A resina composta híbrida demonstrou os melhores resultados. Todos os materiais exibiram aumento de dureza após a realização do polimento, que foi mais evidente após 7 dias. CONCLUSÃO: Pôde-se concluir que, independente do tipo de resina composta, a dureza superficial foi consideravelmente maior quando o polimento foi realizado 1 semana após a confecção dos corpos-de-prova.

Evaluation of the surface hardness of composite resins before and after polishing at different times%Avaliação da dureza superficial de resinas compostas antes e após o polimento em diferentes tempos

PROPOSIÇÃO: O objetivo deste estudo foi avaliar a dureza superficial de seis resinas compostas - Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables), Silux Plus (micropartículas) e Z100 (híbrida) - antes e após o polimento realizado em diferentes tempos. MATERIAL E MÉTODO: Foram confeccionados 240 corpos-de-prova circulares (5mm de diâmetro e 1,4mm de altura). A dureza Vickers foi obtida antes e após o polimento realizado em diferentes tempos: imediatamente, 24 horas, 7 dias e 21 dias após a confecção do corpo-de-prova. Os dados foram analisados estatisticamente por meio da ANOVA e do Teste de Tukey. RESULTADOS: Não houve diferença entre as resinas compostas flowable, as quais apresentaram os menores valores de dureza. A resina composta híbrida demonstrou os melhores resultados. Todos os materiais exibiram aumento de dureza após a realização do polimento, que foi mais evidente após 7 dias. CONCLUSÃO: Pôde-se concluir que, independente do tipo de resina composta, a dureza superficial foi consideravelmente maior quando o polimento foi realizado 1 semana após a confecção dos corpos-de-prova

Evaluation of the surface hardness of composite resins before and after polishing at different times.

PURPOSE: The aim of this study was to evaluate the surface hardness of six composite resins: Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables), Silux Plus (microfilled) and Z100 (minifilled) before and after polishing at different times. MATERIALS AND METHODS: For this purpose, 240 specimens (5mm diameter, 1.4mm high) were prepared. Vickers hardness was determined before and after polishing at different times: immediately, 24h, 7 and 21 days after preparation of the samples. Statistical analysis was performed by ANOVA and Tukey test. RESULTS: There was no difference in the hardness of flowable resins, which had lower hardness than the minifilled resin. The minifilled resin showed the highest surface hardness as compared to the other materials (p<0.01). All materials exhibited higher hardness after polishing, being more evident after 7 days. CONCLUSION: It may be concluded that, regardless of the composite resin, surface hardness was considerably increased when polishing was delayed and performed 1 week after preparation of the samples.

Effect of individual or simultaneous curing on sealant bond strength.

PURPOSE: The objective of this study was to assess the shear bond strength of resin sealants to saliva-contaminated and noncontaminated enamel, comparing 2 curing protocols: (1) individual light-curing of the intermediate bonding agent layer and the sealant; or (2) simultaneous curing of both materials. METHODS: Seventy-two enamel test surfaces were obtained from 24 third molars and randomly assigned to 2 groups (N=36): (A) saliva-contaminated; (B) noncontaminated. Each group was divided into 3 subgroups, according to the bonding technique: (1) Prime&Bond and Fluroshield were light cured separately; (2) Prime&Bond and Fluroshield were light cured together; (3) Fluroshield was applied alone. Shear bond strength was tested at a crosshead speed of 0.5 mm/minute. RESULTS: Means (MPa) were: IA-15.61(+/-4.74); IIA-15.71(+/-6.18); IIIA-13.83(+/-1.50); IB-24.73(+/-4.34); IIB-22.41(+/-4.16); IIIB-18.20(+/-3.58). Statistical analysis revealed that overall bond strength to saliva-contaminated enamel was remarkably lower (P < .05) than that recorded under dry conditions. In both contaminated and noncontaminated groups, significantly higher shear bond strength (P < .05) was observed when the bonding agent was applied underneath the sealant. Comparing the curing protocols for contaminated specimens, no statistically significant difference (P > .05) was observed between individual and simultaneous curing. Conversely, for noncontaminated specimens, bond strength was higher and statistically different (P < .05) when the materials were light cured separately. CONCLUSIONS: Individual or simultaneous curing of the intermediate bonding agent layer and the resin sealant does not seem to affect bond strength to saliva-contaminated enamel. When dry, noncontaminated conditions are maintained, however, the intermediary and the sealing materials should preferably be light cured separately.

Influence of different beverages on the microhardness and surface roughness of resin composites.

This study assessed the influence of different beverages on the microhardness and surface roughness of microfilled (A110, 3M/ESPE), hybrid (Z250 3M/ESPE) and flowable (Flow, 3M/ESPE) resin composites, over time. Twenty-four disc-shaped specimens (10 mm; 2-mm thick) of each resin composite were fabricated, thereby forming three groups (n=24). Knoop microhardness and surface roughness (Ra) were analyzed at predetermined evaluation periods: 24 hours, and 7, 30 and 60 days after specimens fabrication. The 24-hour measurements were recorded after storage in artificial saliva. Next, each group (n=24) was divided into four subgroups (n=6) according to the test beverages: Coca-Cola, sugar cane spirit, coffee and artificial saliva (control). Control specimens were kept in saliva throughout the experiment (60 days). For experimental specimens, a 60-day testing cycle was carried out: specimens were initially stored in saliva for four hours, then submitted to a five-minute immersion in the beverages (Coca-Cola, sugar cane spirit, coffee) intercalated by immersions in saliva three times daily. Microhardness/roughness measurements were done at 7-, 30- and 60-day intervals. Data were submitted to three-way ANOVA and Scheffée test (p<0.05). It was observed that the tested beverages somewhat altered (p<0.05) the composites' microhardness and/or surface roughness. Knoop microhardness-for all resin composites, microhardness remained stable up to the 30-day record, decreasing significantly at the 60-day evaluation. During the interaction beverage X evaluation period, it was observed that the microhardness of materials immersed in coffee and Coca-Cola remained stable up to the seven-day measurement, showing a decrease at the 30-day record and a more accentuated drop at the 60-day evaluation (p<0.05). Specimens immersed in sugar cane spirit exhibited no significant change in microhardness up to the seven-day measurement, increasing significantly at the 30-day record and later decreasing at the 60-day evaluation. Surface Roughness--For all resin composites, surface roughness increased at the seven-day measurement, while decreasing at the 30-day record and even more at the 60-day record. In the interaction beverage X evaluation period, the surface roughness of specimens immersed in test beverages increased at the seven-day measurement, showing a gradual decrease at the following records (30- and 60-day evaluations). The findings of the reported research disclosed that all beverages altered, to some degree, the microhardness and/or surface roughness of the tested resin composites. The alterations' effects ranged from slightly adverse to a markedly negative impact on the composites' microhardness and surface roughness, depending on the characteristics of the materials, type of beverage and the evaluated period. Generally, the greater number of immersions in beverages resulted in a more accentuated impact on the resins' properties.

Tensile bond strength of self-etching adhesive systems to primary dentin.

PURPOSE: To assess in vitro the bond strength of three self-etching adhesive systems to primary teeth dentin. METHODS: Fifteen crowns of primary molars were sectioned mesiodistally and embedded in acrylic resin (n=30). Dentin was exposed and the specimens were randomly assigned in groups (n=10): (1) Clearfil SE Bond; (2) Prime & Bond NT/NRC; and (3) One Up Bond F. A 3 mm-diameter dentin bonding site was demarcated, the adhesive systems were applied and resin composite cones were bonded. After 24 hours in distilled water, tensile bond strength was tested to failure (0.5 mm/minute). Data were submitted to statistical analysis using one-way ANOVA and Scheffé test. RESULTS: Means were (MPa): (1) 16.60 (+/- 4.10); (2) 8.48 (+/- 4.51); and (3) 6.75 (+/- 1.26). CSE Bond yielded significantly higher bond strengths (P < 0.05). Prime & Bond NT/NRC and One Up Bond F means were markedly low and no statistically significant difference was observed between them.

Bond strength of self-etching primer and total-etch adhesive systems to primary dentin.

PURPOSE: The objective of this study was to assess in vitro the tensile bond strength of a self-etching and 2 total-etch, single-bottle adhesive systems to primary dentin. METHODS: Thirty-six sound primary canine buccal surfaces were randomly assigned to 3 groups (N = 12), corresponding to the tested adhesive systems: (1) group I = Excite (EX); (2) group II = Single Bond (SB); and (3) group III = Prompt L-Pop (PLP). After 24-hour storage in distilled water, tensile bond strength was tested for failure at a crosshead speed of 0.5 mm/min. RESULTS: Means (MPa) and standard deviation (+/-) were: (1) EX = 12.72 (+/- .89); (2) SB = 10.86 (+/- 2.09); (3) PLP = 8.66 (+/- 2.23). Single Bond and Excite showed statistically similar results (P >.05) and provided the highest means. Prompt L-Pop was statistically different from the other groups (P < .05) and reached the lower bond strength to primary dentin. CONCLUSIONS: Total-etch agents provided the best overall bonding performance, whereas the all-in-one, self-etching, self-priming adhesive system yielded remarkably lower bond strength to primary teeth dentin.

Microleakage at sealant/enamel interface of primary teeth: effect of Er:YAG laser ablation of pits and fissures.

PURPOSE: The objective of this study was to assess microleakage at sealant/enamel interface after treatment of primary teeth occlusal surfaces with 3 etching techniques. METHODS: Thirty sound primary molars were randomly assigned to 3 groups (N = 10): (1) group I = acid etching for 30 seconds; (2) group II = Er:YAG laser (120 mJ; 4 Hz) plus acid-etching; and (3) group III = Er:YAG laser (120 mJ; 4 Hz). Pits and fissures were sealed with a resin-based sealant (Fluroshield, Dentsply/Caulk). Teeth were isolated, thermocycled, immersed in a 0.2% rhodamine B solution for 24 hours, and serially sectioned. Cuts were analyzed for leakage using an optical microscope connected to a video camera. The images were digitized, and a specific software (Axion Vision) assessed microleakage quantitatively (millimeters). The sealant extension on buccal/lingual cusp heights was measured separately, and the percentage of dye penetration along enamel/sealant interface, in relation to the sealant extension, was calculated. Means of dye penetration were: (1) group I = 2%(+/- 3.75); (2) group II = 2%(+/- 3.38); and (3) group III = 4%(+/- 6.26). Data were submitted to ANOVA and Tukey test. RESULTS: A statistically significant difference (P < .05) was observed between the nonetched lased specimens (group III) and those in the other groups. No significant difference (P >.05) was found between the acid-etched and lased/acid-etched groups (I and II). Fissures prepared with Er:YAG laser alone showed the highest degree of microleakage. All specimens exhibted some degree of leakage. CONCLUSIONS: Laser irradiation did not eliminate the need for acid etching enamel prior to the placement of a pit-and-fissure sealant. The ablation of pits and fissures with an Er:YAG laser device did not yield significantly better marginal sealing at primary enamel/sealant interface, compared to conventional acid etching.

Efeito da técnica adesiva na morfologia da interface adesivo/dentina de vários sistemas adesivos / Effect of the bonding technique on the morphology of dentin/adhesive interfaces bonded with various adhesives systems. SEM investigation

Este estudo analisou, em MEV, o efeito da técnica de adesão na morfologia dasinterfaces adesivas de cinco sistemas total-etch (Scotchbond MP, Single Bond, Optibond FL, Stae, Unibond) e um self-etching (Etch&Prime 3.1). As técnicas úmida e seca foram comparadas. Dezoitodiscos de dentina foram preparados, smear layer padronizada foi produzida e os discos divididos ao meio. Os seguintes protocolos de secagem foram realizados: num hemi-disco, a dentina foimantida úmida; no outro foi seca. Os sistemas adesivos foram aplicados e uma camada da resina Z250 foi acomodada na superfície dentinária e polimerizada. Os espécimes foram seccionados, polidos e preparados para MEV. As interfaces resina-dentina foram analisadas quanto à formação de camada híbrida, enfocado suas características e qualidade. O sistema self-etching não foi capaz de produzir uma camada híbrida consistente, independente da técnica de adesão. As camada híbridas produzidas pelos adesivos total-etch, foram mais espessas e homogêneas quando a técnica úmida foi realizada

This study analyzed, by SEM, the effect of bonding technique on the morphology of dentin/adhesive interfaces of five total-etch (Scotchbond MP, Single Bond, Optibond FL, Stae and Unibond) and one self-etching system (Etch&Prime 3.1). Moist and dry bonding techniques were compared. Eighteen dentin disks were prepared, standardized smear layer was produced and the disks were bisected. The following drying protocols were accomplished: on one half, dentin was kept moist; on the other, dentin was dried. The adhesive systems were applied and a layer of Z250 resin was placed on dentin surface and light-cured. Specimens were sectioned, smoothened and prepared for SEM. The resin-dentin interfaces were analyzed as to the formation of a hybrid layer, focusing on its characteristics and quality. The self-etching system did not produce a consistent hybrid layer, regardless of the bonding technique. The hybrid layers produced by the total-etch adhesives, were always thicker and more homogeneous when the moist technique was performed

Bonding of self-etching and total-etch systems to Er:YAG laser-irradiated dentin. Tensile bond strength and scanning electron microscopy.

This study investigated the effect of Er:YAG laser on bonding to dentin and the interaction pattern of different adhesive systems with the lased substrate. Tensile bond strength of a self-etching [Clearfil SE Bond (CSEB)] and two total-etch [Single Bond (SB) and Gluma One Bond (GOB)] systems to lased and non-lased dentin was evaluated and the adhesive interface morphology was examined by SEM. Dentin was either treated following the manufacturers' instructions (A) or submitted to Er:YAG lasing (80 mJ; 2 Hz) + adhesive protocol (B). Resin cones were bonded to demarcated dentin sites and tested for tensile strength. For SEM, dentin discs were obtained, bisected and the halves were treated (A or B). The adhesive interfaces were examined. Means of tensile bond strength (in MPa) were: CSEB: (A) 20.65+/-1.81, (B) 14.06+/-1.88; SB: (A) 18.36+/-1.48, (B) 16.19+/-1.90; GOB: (A) 16.58+/-1.94, (B) 14.07+/-2.13. ANOVA and Tukey tests showed that lasing of dentin resulted in a significant decrease in bond strength (p<0.05). In the non-lased subgroups, CSEB had higher bond strength than the total-etch adhesives (p<0.05). Conversely, in laser-ablated specimens, CSEB had the lowest bond strength, while SB had the highest values (p<0.05). Consistent hybrid layers were observed for conventionally treated specimens, whereas either absent or scarce hybridization zones were viewed for lased subgroups. Er:YAG laser irradiation severely undermined the formation of consistent resin-dentin hybridization zones and yielded lower bond strengths. CSEB self-etching primer appeared to be the most affected by the laser ablation on the dentin substrate, resulting in the weakest adhesion.

Bond strength of glass-ionomer cements to caries-affected dentin.

PURPOSE: The aim of this study was to assess the tensile bond strength of a resin-modified glass-ionomer cement (a: Fuji II LC) and three traditional glass-ionomer cements (b: Ketac-fil; c: Ketac Molar; d: Fuji IX) to caries-affected dentin. MATERIALS AND METHODS: Forty human permanent molars with occlusal caries in dentin were selected, embedded in polyester resin, and ground until the carious dentin was exposed. Infected dentin was removed with curettes according to the atraumatic restorative technique (ART), and the tooth surface was smoothed with SiC paper. A bonding site, limited to 3 mm in diameter, was treated with polyacrylic acid for 10 s. After surface treatment, an inverted glass-ionomer cone was prepared for each specimen, using a split bisected Teflon matrix. The cones were immediately protected with a thin layer of nail varnish or bonding agent. Specimens were stored in distilled water at 37 degrees C for 24 h, and then bond strength to failure was tested. RESULTS: The mean (SD) bond strengths in MPa were: a: 8.33 (2.35); b: 2.46 (1.60); c: 0.83 (1.18), and d: 1.45 (1.70). The data were analyzed using ANOVA and Tukey statistical tests. Fuji II LC, a resin-modified glass-ionomer cement, showed higher bond strength values and was statistically superior to the other groups, containing traditional glass ionomer cements (p < 0.05). CONCLUSION: Findings showed that the traditional glass-ionomer cements tested in this study had lower mean bond strength values to caries-affected dentin than did the resin-modified glass-ionomer cement.

In vitro evaluation of microleakage of a flowable composite in Class V restorations.

The aim of this study was to evaluate microleakage around class V restorations using a flowable composite compared to a hybrid composite. Forty class V cavities were prepared on buccal and lingual surfaces of 20 human teeth, with occlusal and cervical margins at the enamel and cementum/dentin levels, respectively. Specimens were divided into 2 groups with 10 samples each. Group 1: buccal cavities received Paama 2 (conventional bonding agent) + Wave (flowable composite); lingual cavities were restored with Paama 2 + Glacier (hybrid composite). Group 2: buccal cavities received Optibond Solo (self-priming bonding agent) + Wave; lingual cavities were restored with Optibond Solo + Glacier. After being stored in distilled water and finished, the teeth were thermocycled, immersed in a 50% silver nitrate solution and embedded in resin. They were sectioned and the depth of tracer penetration was scored. The results were analyzed using Kruskal-Wallis and Wilcoxon tests. The restorations with flowable composite and those with hybrid composite from the same group showed similar results of microleakage for both occlusal and cervical margins. Optibond Solo improved the sealing of the restorations when compared with Paama 2 (p < 0.01). None of the restorative materials completely sealed the tooth/restoration interface at the cervical margins.

Assessing microleakage in resin composite restorations rebonded with a surface sealant and three low-viscosity resin systems.

OBJECTIVES: The aim of this study was to assess the ability of three low-viscosity resin systems (Unibond, Single Bond, and Fluorseal), used as rebonding agents, and a specific surface-penetrating sealant (Fortify) to prevent microleakage in Class V resin composite restorations. METHOD AND MATERIALS: Fifty Class V cavities with the occlusal margin in enamel and the cervical margin in dentin and cementum were prepared on both the buccal and lingual surfaces of sound extracted premolars and restored with a hybrid light-cured resin composite. After finishing and polishing, restorations were randomly assigned to one of five equal groups (n = 10): a control, without surface sealing, and four experimental groups in which margins were etched and rebonded. Specimens were thermocycled, immersed in a 50% silver nitrate solution, sectioned longitudinally, and analyzed for leakage at the occlusal and cervical interfaces. RESULTS: Statistical analysis showed significantly less leakage at the enamel margins for all groups. Fortify and Unibond were statistically similar and provided better marginal sealing at dentin and cementum interfaces. Fluorseal showed the poorest ability to prevent microleakage. CONCLUSION: The rebonding technique may substantially minimize microleakage at dentin and cementum margins of composite restorations, when a resin system with sufficiently low viscosity is used as a surface sealant, regardless of whether it has been specified for such a purpose.

In vitro evaluation of microleakage of a flowable composite in class V restorations

The aim of this study was to evaluate microleakage around class V restorations using a flowable composite compared to a hybrid composite. Forty class V cavities were prepared on buccal and lingual surfaces of 20 human teeth, with occlusal and cervical margins at the enamel and cementum/dentin levels, respectively. Specimens were divided into 2 groups with 10 samples each. Group 1: buccal cavities received Paama 2 (conventional bonding agent) + Wave (flowable composite); lingual cavities were restored with Paama 2 + Glacier (hybrid composite). Group 2: buccal cavities received Optibond Solo (self-priming bonding agent) + Wave; lingual cavities were restored with Optibond Solo + Glacier. After being stored in distilled water and finished, the teeth were thermocycled, immersed in a 50 percent silver nitrate solution and embedded in resin. They were sectioned and the depth of tracer penetration was scored. The results were analyzed using Kruskall-Wallis and Wilcoxon tests. The restorations with flowable composite and those with hybrid composite from the same group showed similar results of microleakage for both occlusal and cervical margins. Optibond Solo improved the sealing of the restorations when compared with Paama 2 (p<0.01). None of the restorative materials completely sealed the tooth/restoration interface at the cervical margins

Avaliaçäo in vitro da microinfiltraçäo marginal em restauraçöes classe V de materiais restauradores estéticos / In vitro evaluation of marginal microleakage on class V restoration of esthetics materials

O propósito deste estudo foi avaliar in vitro a infiltraçäo marginal de duas resinas compostas modificadas por poliáciso - F2000(3M) e Freedom (SDI) - comparando-as a um cimento de ionômero de vidro modificado por reina - Vitremer (3M). Para tanto, 30 preparos classe V - com 2 mm de profundidade e dimensöes mesiodistal e ocluso-gengival de 4 mm e 3 mm, respectivamente - foram confeccionados em pré-molares e caninos humanos e divididos aleatoriamente em 3 grupos iguais (n=10). As cavidades foram tratadas e entäo restauradas seguindo-se as instruçöes da bula de cada material. Os dentes ficaram armazenados por 7 dias em 100 por cento de umidade relativa a 37ºC em estufa e após esse período foi realizado o polimento. Os espécimes foram submetidos a ciclagem térmica (600 ciclos), impermeabilizados com esmalte cosmético, deixando-se uma janela de 1 mm em torno da restauraçäo sem isolar, e a seguir foram imersos em soluçäo de nitrato de prata a 50 por cento por 8 horas. Os dentes foram lavados, incluídos em resina acrílica, seccionados longitudinalmente e avaliados seguindo-se escores de 0 a 3. A análise estatística dos dados pelos testes de Wilcoxon e Kruskall-Wallis revelou que na regiäo de esmalte os materiais testados apresentaram completo vedamento marginal em praticamente todos os espécimes, näo havendo diferença estatística significante entre eles. Na margem dentina/cemento, o Vitremer e o F2000 promoveram melhor selamento quanto comparados ao Freedom, que apresentou os resultados mais insatisfatórios. Com base nesses dados pode-se concluir que nenhum dos materiais testados propiciou completo vedamento da margem com término cervical em dentina/cemento