In vitro-evaluation of secondary caries formation around restoration.
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The objective of this in vitro study was to evaluate demineralization around restorations. Class V preparations were made on the buccal and lingual surfaces of each tooth. TPH (Group 1), Fuji II LC (Group 2), Tetric (Group 3), Dyract (Group 4), GS 80 (Group 5) and Chelon Fil (Group 6) were randomly placed in equal numbers of teeth. The teeth were submitted to a pH-cycling model associated with a thermocycling model. Sections were made and the specimens were examined for the presence of demineralization under polarized light microscopy. Demineralization was significantly reduced with Chelon Fil (Group 6). Furthermore, a similar inhibitory effect on the development of demineralization was observed in Groups 2, 4 and 5. (+info)
Ultrastructural examination of one-step self-etch adhesive bonded primary sound and caries-affected dentin.
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PURPOSE: To examine the ultrastructure and silver nanoleakage of the resin-dentin interfaces in sound and caries-affected primary tooth dentin bonded with a 4-META one-step self-etch adhesive. METHODS: Each of five sound and carious primary molars was bonded with Hybrid Bond. Resin-dentin interfaces were observed with TEM micrographs obtained from silver-impregnated, unstained and undemineralized sections of bonded sound and caries-affected primary dentin, and stained and demineralized sections of bonded sound and caries affected primary dentin without silver impregnation. RESULTS: For sound dentin, silver nanoleakage was observed extensively in the patent dentin tubules, within the dentin beneath the hybrid layer, within the hybrid layer in some specimens, and as water trees that partially protruded into the overlying adhesive layer. The hybrid layer was about 1 microm thick. Smear plugs in the dentin tubules and smear on the ground dentin protruded in the hybrid layer. Remnants of demineralized smear were observed overlying the adhesive layer. For caries-affected dentin, the hybrid layer was obscure. Dentin tubules were occluded with mineral deposits. There were no water trees or nanoleakage in the adhesive layer or hybrid layer. However, smear remnants were observed in the adhesive layer and large silver deposits were observed in the highly porous underlying caries-affected dentin. (+info)
Influence of microleakage, surface roughness and biofilm control on secondary caries formation around composite resin restorations: an in situ evaluation.
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Effects of mechanical and thermal aging on microleakage of different fissure sealants.
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The purpose of this study was to examine the microleakage of three different fissure sealants after they were aged by mechanical loading and thermocycling in vitro. To this end, a bonding agent (Prime & Bond NT) and three different fissure sealants (Clinpro, Helioseal F, Teethmate F1) were used, whereby microleakage was evaluated using a dye penetration method after mechanical loading and/or thermocycling. Sealant-treated teeth were allocated into four groups: mechanical loading (50,000 times), thermocycling (10,000 times), mechanical loading (50,000 times) + thermocycling (10,000 times), and one control group. For each fissure sealant, both experimental and control groups showed statistically significant differences in average microleakage score (p < 0.05). Further, for each fissure sealant, the highest average microleakage score was obtained in mechanical loading + thermocycling group. When comparison was done for each aging method, the average microleakage scores showed statistically significant differences among the three fissure sealants (p < 0.05). Based on the results of this study, it was also concluded that it is necessary to develop reliable in vitro test methods for dental materials. (+info)
In vitro evaluation of matched-taper single-cone obturation with a fluid filtration method.
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OBJECTIVE: Widespread use of rotary nickel-titanium systems has caused manufacturers to produce gutta-percha cones that match the taper of the canals prepared with these systems. Obturations with these cones may provide 3-dimensional obturation of the root canal in less time. The aim of this study was to use a fluid filtration method to compare the apical sealing ability of matched-taper single-cone, Thermafil and lateral condensation obturations. MATERIALS AND METHODS: Sixty-six extracted human lower premolar teeth were instrumented to size F3 with ProTaper instruments. The teeth were divided into 3 groups and obturated with matched-taper single-cone, Thermafil and lateral condensation techniques. AH Plus was used as a sealer. Six teeth were used as positive and negative controls. A fluid filtration system was used to evaluate the apical seal. Measurements were made at 2-minute intervals for 8 minutes and the average of these values was recorded. One-way analysis of variance test was used for statistical analysis. RESULTS: Mean leakage values for the lateral condensation, single-cone and Thermafil groups were 0.49 +/- 0.37 microL min(-1), 0.39 +/- 0.24 microL min(-1) and 0.44 +/- 0.25 microL min(-1), respectively. The difference between the groups was not statistically significant (p > 0.05). CONCLUSIONS: The apical sealing ability of matched-taper single-cone obturation was comparable with that of lateral condensation and Thermafil techniques. (+info)
Influence of human and bovine substrate on the microleakage of two adhesive systems.
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Comparison of apical and coronal sealing in canals having tapered cones prepared with a rotary NiTi system and stainless steel instruments.
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The purpose of this study was to compare the sealing ability of different tapered gutta percha cones that were used with lateral compaction and single cones in canals prepared with various root canal instruments. One hundred extracted maxillary incisor roots were used. In group 1, 30 roots were prepared with stainless steel instruments (SS) and then filled by the lateral compaction technique using .02 tapered master cones. In group 2, 30 roots were prepared with ProFile nickel titanium instruments (NiTi) and filled in the same way as group 1. In group 3, 30 roots were filled by the single cone technique using 0.06 tapered gutta-percha cones. The remaining 10 teeth were taken as two control groups. Apical and coronal leakage was evaluated using the fluid filtration model. Considering the effects of the instrumentation, no statistically significant differences were found between the groups prepared with SS and NiTi (P > 0.05). When the effects of obturation technique were taken into consideration, the ProFile instruments and lateral compaction resulted in significantly less coronal leakage than the SS instruments and lateral compaction (P < 0.05). There were no significant differences in apical leakage among any of the groups (P > 0.05). (+info)
Microleakage beneath brackets bonded with flowable materials: effect of thermocycling.
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