effect of duration of finishing and polishing on the surface roughness of two composite resins

The purpose of this study was to evaluate the effect of duration of finishing and polishing procedures on the surface roughness of two different types of composite resins. Forty samples of 6 mm in diameter and 2 mm in depth were prepared, 2 types of composite resins were used [nanocomposite and hybrid composite resin]. Twenty samples of each type of material were prepared and divided into two main groups and then each main group subdivided randomly into two subgroups of 10 samples for each subgroup [one]. Ten samples of each material were submitted to finishing by using a finishing kit. The available finishing kits used in this study containing discs, cups and points that were used with a slow-speed hand piece in a dry field and with a light intermittent pressure for about 15 seconds. While the other 10 samples of each material were finished for about 30 second; then the analysis of the surface roughness was carried out, three readings were made on each surface using a stylus tip and the extension of each reading was 2 mm stroke. There was non significant difference between the groups that were finished and polished for 15 second and the other groups that were finished and polished for 30 second for the two different types of composite resin. Increasing duration of finishing and polishing has no effect on the surface roughness of the two different types of composite resin

Coronal sealing ability of different sealers on teeth obturation and the effectiveness of two different obturation techniques

The purpose of this study was to evaluate the effect of two sealers on coronal seal and the coronal sealing ability of two obturation techniques. Forty extracted single-rooted human teeth were instrumented with the step-back technique and were irrigated with 5.25% sodium hypochlorite [NaOCl]. The smear layer was removed by washing with 10 ml of 17% ethylene diamine tetra-acetic acid [EDTA] and 10 ml of 5.25% [NaOCl]. All instrumented root canals were randomly divided into two experimental groups; Group A: 20 roots epoxy resin sealer [AH26] was used, Group B: 20 roots Zinc oxide euginol [ZOE] sealer was used. Each group of main groups were subdivided randomly into two obturation groups; 1. 10 roots obturated by thermo plasticized technique [obtura II], 2. 10 roots obturated by cold lateral compaction tech-nique. The root surfaces were then coated with nail polish except for the coronal, then dye penetration study was conducted and samples were examined under the stereomicro-scope. Data had been collected from three independent examiners and statistically analyzed using student t-test. There were significant differences between AH26 with ZOE in group obturated by obtura II and when obtura II technique compared with the cold lateral compaction technique in group of AH26 sealer. Epoxy resin sealer [AH26] and obtura II gave the best results in coronal sealing when compared with Zinc oxide euginol sealer and cold lateral compaction technique

Obturation of internally prepared cavities [simulating internal resorption] with three different techniques

There is controversy as to which instrumentation and/or obturation techniques to choose for the treatment of the internal resorption defects. This in vitro study compared the instrumentation and obturation quality of simulated internal resorption cavities [IRC] with 3 different techniques. Ninety extracted human roots were used and sectioned transversely 5 mm from the apex and hemi-circular cavities were prepared in both sections. The sections were glued back together using superglue and embedded in plaster mold, thus obtaining root canals with cavities simulating internal resorption. The samples were randomly divided into 3 groups of 30 roots and instrumented by protaper rotary files, hybrid technique, or stepback technique, then each group subdivided into three subgroups of 10 roots and obturated with cold lateral condensation, warm vertical compaction, or injectable thermoplasticized technique. After obturation, the samples were radiographed in Bucco-lingual and Mesiodistal view. After that, the plaster molds were removed, and the samples were then sectioned at the previous level and the quality of the obturation of the IRC were viewed under stereomicroscope. There was highly significant difference between protaper rotary files compared with hybrid and stepback techniques. The results of obturation techniques radiographically and by stereomicroscope showed that there was highly significant difference in between injectable thermo-plasticized compared with other two techniques. The pro-taper rotary files and injectable thermo-plasticized technique gave the best results for treatment of simulated internal resorption cavities [IRC]