Influence of Different Enamel Substrates on Microtensile Bond Strength of Sealants After Cariogenic Challenge

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Purpose: To evaluate the microtensile bond strength (mu TBS) of resin sealer on enamel substrates after cariogenic challenge. Materials and Methods: Enamel blocks were obtained from human third molars and randomly divided into 6 groups (n = 10) according to enamel substrates (S: sound, CL: caries-like lesion, or CLTF: caries-like lesion + topical fluoride application) and sealant material (F: FluroShield, or H: Helioseal Clear Chroma). Sealants were placed on enamel surfaces, stored in 100% humidity (24 h, 37 degrees C), and longitudinally sectioned into hourglass shapes. According to the groups, pH cycling was applied and the mu TBS test was performed. The fracture patterns were assessed by SEM. Results: Regarding substrates, the highest mu TBS values in MPa were observed for CLTF enamel (26.0 +/- 7.6), followed by S (22.0 +/- 7.4) and CL (15,5 +/- 4.9). A significant interaction was found between material and pH cycling (p = 0.0395). F (23.9 +/- 7.6) showed higher mu TBS values than H (18.3 +/- 7.5) when submitted to pH cycling. The majority of samples presented mixed failure. Conclusions: Enamel substrate significantly affected mu TBS, with the highest values for remineralized caries-like enamel lesions. Furthermore, mu TBS values were dependent on both materials and pH cycling.132131137Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/60595-1

Effects of resin luting agents and 1% NaOCl on the marginal fit of indirect composite restorations in primary teeth

Objective: The purpose of this study was to provide information regarding the marginal adaptation of composite resin onlays in primary teeth previously treated with 1% sodium hypochlorite (NaOCl) (pulp irrigant) using two different resin luting agents. Material and Methods: Forty extracted sound primary molars had their crowns prepared in a standardized machine and were randomly divided into 4 groups (n=10): G1 (1% NaOCl irrigation+EnForce); G2 (EnForce); G3 (1% NaOCl irrigation+Rely X); G4 (Rely X). The onlays were made with Z250 composite resin on plaster models. After luting, the tooth/restoration set was stored in 100% relative humidity at 37 degrees C for 24 h and finished with Soflex discs. Caries Detector solution was applied at the tooth/restoration interface for 5 s. The specimens were washed and four digital photos of each tooth were then taken. The extents of the gaps were measured with Image Tool 3.0 software. The percentage data were submitted to a Kruskal-Wallis test (alpha=0.05). The Relative Risk test analyzed the chance of a gap presence correlated to each group. Results: There were no statistically significant differences (p>0.05) among the groups. The relative risk test revealed that some groups were more apt to have a presence of gaps than others. Conclusion: Neither the 1% NaOCl treatment nor the resin luting agents caused any alterations in the dental substrate that could have influenced the marginal adaptation of composite onlays in primary teeth.19545546

Marginal adaptation of pit and fissure sealants after thermal and chemical stress. A SEM study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Purpose: To evaluate the in vitro marginal adaptation (gap formation) in the fissure of different sealer materials (resin sealant, glass-ionomer cement, resin-modified glass-ionomer cement, and adhesive system) submitted to thermal and chemical stress, using scanning electron microscopy evaluation (SEM). Methods: 80 impacted human third molars were randomly assigned to the following experimental groups (n=10): FluroShield (F), Helioseal Clear Chroma (H), Vitremer (V), Fuji II-LC (FII), Ketac-Molar (KM), Fuji IX (FIX), Single Bond (SB), and Clearfil Protect Bond (CF). All groups were subjected to thermocycling and 14 days of pH cycling. A blinded and calibrated examiner performed SEM analysis. Gap formation was scored according to: 0= no sealant marginal gaps; 1= sealant marginal gaps present or total sealant loss. The score 0 was considered a success, while score 1 represented failure. Data were analyzed by Kruskal-Wallis and Bonferroni tests (P< 0.05). Results: The success rates of SB (100%) and V (90%) were similar, but statistically superior to F (30%), H (20%), FIX (20%0), and CF (0%) (P< 0.05). A tendency for similar behaviors of FII and KM to SB and V was observed and for similar behaviors of F, FIX and H to CF. The worst results were obtained for CF. (Am J Dent 2008;21:377-382).216377382Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

NaOCl effects on primary and permanent pulp chamber dentin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Objectives: The dentin quality of primary and permanent pulp chamber was inspected by Fourier-transformed Raman spectroscopy (FT-Raman) and scanning electron microscopy (SEM). Fragments of pulp chamber dentin were obtained from 20 human molar crowns (primary and permanent). Methods: The fragments were assigned to 8 groups (n = 5)-Primary teeth: G1, pulp chamber dentin; G2, pulp chamber dentin irrigated with NaOCl 1% (30 min); G3, pulp chamber dentin irrigated with NaOCl 1% (30 min) and etched by 35% phosphoric acid; G4, pulp chamber dentin etched by 35% phosphoric acid. Permanent teeth: G5, pulp chamber dentin; G6, pulp chamber dentin irrigated with NaOCl 1% (30 min); G7, pulp chamber dentin irrigated with NaOCl 1% (30 min) and etched by 35% phosphoric acid; G8, pulp chamber dentin etched by 35% phosphoric acid. The spectra were subjected to the Cluster analysis. The SEM images were scored. Results: Inorganic content: There was a difference between primary and permanent dentin. The groups treated with NaOCl were statistically similar between them, but differed from the groups not treated. Organic content: There was no difference between primary and permanent dentin. The groups became similar after NaOCl and phosphoric acid treatments. The microscopic images showed the presence of calcospherites on permanent dentin and their absence on primary dentin. Conclusions: The NaOCl changed the inorganic content in both dentitions; regardless of the following phosphoric acid etching. However, the chemical changes caused by NaOCl were not detected by SEM when it was followed by etching. (C) 2008 Elsevier Ltd. All rights reserved.369745753Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [#05/50811-9, 01/133848

Effects of Chemical Agents on Physical Properties and Structure of Primary Pulp Chamber Dentin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This study evaluated the effects of chemical agents on the physical properties and structure of primary pulp chamber dentin using surface roughness, microhardness tests, and scanning electron microscopy (SEM). Twenty-five primary teeth were sectioned exposing the pulp chamber and were divided into five groups (n=5): NT, no treatment; SH1, 1% sodium hypochlorite (NaOCl); SH1U, 1% NaOCl+Endo-PTC (R); SH1E, 1% NaOCl+17% EDTA; and E, 17% EDTA. After dentin treatment, the specimens were submitted to roughness, microhardness testing, and SEM analysis. Roughness and microhardness data were submitted to one-way ANOVA and Tukey's test (P0.05). Microhardness values could not be obtained in the EDTA groups (SH1E and E). The presence of intertubular dentin with opened dentin tubules was observed in the NT, SH1, and SH1U groups. SH1E showed eroded and disorganized dentin with few opened tubules and the intertubular/peritubular dentin was partially removed. Considering the physical and structural approaches and the chemical agents studied, it can be concluded that NaOCl and NaOCl associated with Endo-PTC (R) were the agents that promoted the smallest changes in surface roughness, microhardness, and structure of the pulp chamber dentin of primary teeth. Microsc. Res. Tech. 77:52-56, 2014. (c) 2013 Wiley Periodicals, Inc.7715256Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/58561-1

Inhibition of enamel mineral loss by fissure sealant: An in situ study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Objectives: This study evaluated the effect of fluoride and non-fluoride sealants on hardness decrease (HD) and marginal adaptation (MA) on enamel substrates after cariogenic challenge. Methods: Occlusal enamel blocks, from human third molars, were randomly divided into six groups (n = 12), according to occlusal fissures condition (S - sound; C - caries-like lesion; CF - caries-like lesion + topical fluoride) and sealants (F - FluroShield; H - Helioseal Clear Chroma). Lesion depths were 79.3 +/- 33.9 and 61.3 +/- 23.9 for C and CF groups, respectively. Sealants were placed on occlusal surface and stored at 100% humidity (37 degrees C; 24 h/d). HD was measured by cross-sectional microhardness analysis at the sealant margin distances: -1 (under sealant), 0 (sealant margin), 1, 2 (outer sealant). Sealant MA was observed by polarized light microscopy and scored according to: 0 - failure (no sealant MA or total sealant loss); 1 - success (sealant MA present). MA and HD were analysed by ANOVA-R and mixed model analysis, respectively. Results: For HD (Delta S), F values (6900.5 +/- 3686.6) were significantly lower than H values (8534.6 +/- 5375.3) regardless of enamel substrates and sealant margin distances. Significant differences were observed among sealant margin distances: -1 (5934.0 +/- 3282.6) < 0 (8701.5 +/- 6175.7) = 1 (8473.2 +/- 4299.4) = 2 (7761.5 +/- 4035.1), regardless of sealant and substrate. MA was similar for all groups (p >= 0.05). Conclusion: MA was not affected by sealant type or substrate condition, whereas enamel HD was favourably impacted by fluoride in the sealant. In addition, sealants were more effective as a physical barrier than as its chemical potency in reducing enamel HD. Clinical significance: Sealing with a fluoride material is a recommended procedure to prevent caries of occlusal permanent molars in high-caries-risk patients, even though those exhibiting white spot lesions, since the enamel hardness decrease when fluoride sealant was used in vitro. (C) 2012 Elsevier Ltd. All rights reserved.4114250Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/60595-1