Comparison of final irrigation techniques in removal of calcium hydroxide.

The aim of this study was to compare new irrigation systems with a conventional irrigation technique for the removal of inter-appointment calcium hydroxide [Ca(OH)2 ]. Forty-seven extracted human single-rooted teeth were instrumented, and Ca(OH)2 paste was placed into root canals by using a lentulo spiral at the apical third. Teeth were randomly divided into three groups according to different irrigation protocols using a 30-gauge slot-tipped needle, EndoVac system and ProUltra® PiezoFlow™ ultrasonic irrigation system. Scanning electron microscopic images of the selected root canal surfaces (cervical, middle and apical third) were evaluated using a 5-grade scale. The influence of the irrigation system was evaluated using a two-way analysis of variance test and Tukey's test. The EndoVac and PiezoFlow groups demonstrated the lowest scale values (cleanest canals); however, there was no statistical difference between these two groups. The conventional irrigation group exhibited significantly higher scores (P < 0.05). The conventional needle irrigation was not sufficient to remove Ca(OH)2 from the root canal system. Irrigation with EndoVac and PiezoFlow™ ultrasonic irrigation systems improved the removal of the intracanal medicament resulting in cleaner root canal walls.

Effect of sodium ascorbate on the bond strength of silorane and methacrylate composites after vital bleaching.

We investigated the effect of sodium ascorbate (SA) on the microtensile bond strengths (MTBSs) of different composites to bovine enamel after vital bleaching with hydrogen peroxide (HP) or carbamide peroxide (CP). Thirty bovine incisors were randomly divided into five groups and treated with no bleaching application (control), 35% HP alone, 35% HP+10% SA for 10 minutes (HP+SA), 16% CP alone, or 16% CP+10% SA for 10 minutes (CP+SA). Specimens were restored with Silorane adhesive and Filtek Silorane composite (designated as S/group) or with Clearfil SE bond and Filtek Supreme XT (designated as F/group). Composite build-up was created on the enamel. Sectioned specimens (n=10 per group; 1 mm2; cross-sectional area) were created and stressed in a universal testing machine at 1 mm/min crosshead speed. The application of 10% SA immediately after bleaching with 16% CP or 35% HP increased the enamel MTBS, regardless of the adhesive/composite resin used. The resulting MTBS values were similar to those of the control groups. Use of 16% CP and 35% HP alone decreased the enamel MTBS, regardless of the adhesive/composite resin used, with F/CP+SA=F/HP+SA=F/CP=S/CP+SA=S/HP+SA=S/C>S/CP=S/HP=F/CP=F/HP (p<0.05). We concluded that the application of SA for 10 minutes immediately after vital bleaching increases the enamel BS for dimethacrylate- and silorane-based composites.

Effect of sodium ascorbate on the bond strength of silorane and methacrylate composites after vital bleaching

We investigated the effect of sodium ascorbate (SA) on the microtensile bond strengths (MTBSs) of different composites to bovine enamel after vital bleaching with hydrogen peroxide (HP) or carbamide peroxide (CP). Thirty bovine incisors were randomly divided into five groups and treated with no bleaching application (control), 35% HP alone, 35% HP + 10% SA for 10 minutes (HP + SA), 16% CP alone, or 16% CP + 10% SA for 10 minutes (CP + SA). Specimens were restored with Silorane adhesive and Filtek Silorane composite (designated as S / group) or with Clearfil SE bond and Filtek Supreme XT (designated as F / group). Composite build-up was created on the enamel. Sectioned specimens (n = 10 per group; 1 mm2; cross-sectional area) were created and stressed in a universal testing machine at 1 mm/min crosshead speed. The application of 10% SA immediately after bleaching with 16% CP or 35% HP increased the enamel MTBS, regardless of the adhesive / composite resin used. The resulting MTBS values were similar to those of the control groups. Use of 16% CP and 35% HP alone decreased the enamel MTBS, regardless of the adhesive / composite resin used, with F / CP + SA = F / HP + SA = F / CP = S / CP + SA = S / HP + SA = S / C > S / CP = S / HP = F / CP = F / HP (p < 0.05). We concluded that the application of SA for 10 minutes immediately after vital bleaching increases the enamel BS for dimethacrylate- and silorane-based composites.

Effects of air-polishing powders on color stability of composite resins.

OBJECTIVES: The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials. MATERIAL AND METHODS: Thirty cylindrical specimens (15×2 mm) were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex). The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C) and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder). A standard air-polishing unit (ProSmile Handly) was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90°. Specimens were stored in 100 mL of coffee (Nescafe Classic) for 24 h at 37°C. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300). Color differences (∆E*) between the 2 color measurements (baseline and after 24 h storage) were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p<0.05). RESULTS: According to the 2-way ANOVA results, composite resin restorative materials, air-polishing powders, and their interaction were statistically significant (p<0.05) For Aelite Aesthetic Enemal, Filtek Z250, Grandio, CeramX Mono, and Quixfil composite resin restorative materials, no significant difference was observed between Group-PS and Group-CP (p>.05) and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less ∆E* values than the other composite resins tested. The highest ∆E* values were observed in Quixfil. CONCLUSION: Except for Quixfil, all control groups of composite resins that were polished Sof-Lex exhibited clinically acceptable ∆E values (<3.7). Air-polishing applications increased the color change for all composite resin restorative materials tested. Composite restorations may require re-polishing after air-polishing.

Effect of filler ratio in adhesive systems on the shear bond strength of resin composite to porcelains.

This in vitro study evaluated the effect of six different adhesive systems on the shear bond strength of resin composite to feldspathic and low-fusing porcelains. Sixty porcelain blocks were prepared for each low-fusing (Matchmaker) and feldspathic (MVK95) porcelain specimen. After surface preparation, the porcelain specimens were divided into six groups (n = 10) for different adhesive systems (Adper Prompt L-Pop, QuadrantUnil Bond, Te-Econom, PQ1, One-StepPlus and Prime&Bond NT). After adhesive application, a universal resin composite (FiltekZ250) was condensed on the specimens. The prepared specimens were then stored in distilled water at 37 degrees C for 24 hours, then all the samples were thermal cycled 1000 times between 5 degrees C and 55 degrees C. Shear testing was performed on a universal test machine using a crosshead speed of 0.5 mm/minute. The statistical analysis of the bond strength data included two-way ANOVA. Then, the means were compared by Tukey HSD test (alpha = 0.05). The lowest bond strength was observed in Adper Prompt L-Pop. No statistically significant difference was observed between One-Step Plus and Prime&Bond NT. The highest bond strength was observed in PQ1. When low-fusing or feldspathic porcelain restorations are repaired with resin composite, self-etching adhesive systems may not be indicated. If maximum bond strength is the goal in porcelain resin bonding, adhesive systems that have a high filler ratio should be used.

Effects of polishing procedures on color stability of composite resins.

The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme). Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd), polishing discs then diamond polishing paste (PdP), polishing discs then a liquid polishing system (Biscover) (PdB), and combinations of these (PdPB) were used. Unpolished specimens served as the control (C). The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change (DeltaE*) were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (alpha=0.05). The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme). The posterior (Filtek P60) and universal (Filtek Z250) composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA), were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme) and universal (Quadrant LC) composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish system (PdB and PdPB groups).

The pH changes of calcium hydroxide mixed with six different vehicles.

OBJECTIVE: The aim of this study was to determine the pH values of calcium hydroxide mixed with sterile saline, glycerin, Xylocaine pump spray, Citanest Octapressin, 0.2% chlorhexidine solution, and Ultracaine DS. STUDY DESIGN: pH values of all vehicles were measured by a pH microelectrode before calcium hydroxide powder was added to 2 mL of the vehicle until the solutions were saturated (n = 10). After all the saturated samples were prepared, pH was remeasured at 0, 10, 20, 30, and 45 minutes; 1, 24, and 48 hours; and 7 days. RESULTS: When pH changes over the time course were compared, there were no statistically significant differences among mean pH values of 0, 10, 20, 30, 45 minutes, 1 hour, and 24 hours (P = .754) and mean pH values of these groups were significantly lower than the mean pH value of 48 hours and 7 days (P < .05). The highest mean pH value was observed at day 7. When different vehicles were compared, the lowest mean pH value was observed in sterile saline. The mean pH value of Xylocaine was the highest (P < .05). CONCLUSION: The result of this study indicated that when calcium hydroxide powder was mixed with glycerin, Xylocaine pump spray, Citanest Octapressin, 0.2% chlorhexidine solution, Ultracaine DS, and sterile saline solution, the mixtures became very highly alkaline. However, the pH values of the mixtures increased significantly after 24 hours. When one of these vehicles is used for root canal medication, a calcium hydroxide mixture might be left in place at least 7 days.

Nonsurgical endodontic retreatment of geminated teeth: a case report.

The purpose of this case presentation is to describe nonsurgical retreatment of anterior teeth with gemination. A 21-year-old male patient was referred for endodontic treatment of his maxillary left lateral incisor. In the clinical examination, a large crown was observed in the left maxillary incisor region when compared with the right maxillary lateral incisor. In the present case, a tooth gemination of a maxillary lateral incisor has been described. A periapical radiograph showed that the tooth had partially separated two crowns having a single root and one root canal, but the access cavity of the distal crown had not been opened, and the root canal had been obturated with single cone technique. Nonsurgical endodontic retreatment was decided for geminated lateral incisor. At the 6-month follow-up, the tooth was asymptomatic and there was no radiolucency around the apical region.

Effects of different root canal obturation techniques on bacterial penetration.

OBJECTIVES: The aim of this study was to compare bacterial penetration following obturation with 5 different techniques. STUDY DESIGN: This study was performed on 120 teeth including negative control (n = 10), positive control (n = 10), and experimental groups (n = 100). One hundred teeth were randomly divided into 5 groups of 20 teeth each and obturated with System B (Sb), Lateral Compaction (Lc), Thermafil (T), Single ProTaper Gutta-percha (P), and laterally compacted ProTaper Gutta-percha (PLc). Enterococcus faecalis was used for determination of the bacterial penetration. Evaluation was carried out for 60 days. RESULTS: At 30 days, the chi2 test showed that the slowest penetration was observed in Group Sb and Group PLc, which were not significantly different from each other. The fastest penetration in the all experimental groups was observed in Group T and Group P, which were not significantly different from one another. Also, there was no statistically significance difference (P > .05) among all groups at 60 days. CONCLUSION: It may be concluded that under the conditions of this study System B and laterally compacted ProTaper Gutta-percha prevent bacterial penetration of the root canal at 30 days. Furthermore, there was no difference among obturation techniques at 60 days.

Color stability of resin composites after immersion in different drinks.

The purpose of this study was to evaluate the discoloration of two nanohybrids, two microhybrids, and a posterior composite resin restorative material upon exposure to different drinks--namely tea, cola, coffee, red wine, and water. The colors of all specimens before and after storage in the solutions were measured by a colorimeter based on CIE Lab system, and the color differences thereby calculated. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's HSD test. According to ANOVA, the restorative material, staining agent, and their interaction were found to play a statistically significant role (P = 0.0001) in color change. Among the staining agents, water consistently showed the lowest deltaE* value for all materials, whereas red wine showed the highest deltaE* value. In other words, for all the materials tested, their color change in staining agents ranked in this increasing order: water < cola < tea < coffee < red wine. In terms of comparison among the five restorative materials, Filtek P60 and Z250 were observed to manifest less color change than the nanohybrids and Quadrant LC.

Bacterial penetration after obturation with four different root canal sealers.

The aim of this study was to compare bacterial penetration after obturation with lateral compaction technique using four different root canal sealers. This study was performed on 100 teeth including negative control (n = 10), positive control (n = 10), and experimental groups (n = 80). 80 teeth were randomly divided into five groups of 20 teeth each and obturated with AH 26 (A), AH Plus (AP), Sealapex (S), Ketac-Endo (K) root canal sealers. Evaluation was carried out for 60 days. After 30 days of comparing the bacterial penetration values, total penetration was observed in 85% of the Group AP, and group K, 80% of the group S, and 75% of the group A. According to the results of chi(2) test, there was no statistically significant difference observed between any groups (p > 0.05). After 60 days of comparing the bacterial penetration values, total penetration was observed in 100% of the group AP, group K, and group S and 95% of the group A. It may be concluded that under the conditions of this study, there was no difference in the bacterial penetration of the four root canal sealers tested at 30 and 60 days.

Effect of thermal cycling on microleakage of a fissure sealant polymerized with different light sources.

The purpose of this study was to examine the effect of thermal cycling on microleakage of a fissure sealant after it was bonded with different bonding agents and polymerized with different light curing units. To this end, two bonding agents (Xeno III, iBond), three light curing units (Astralis 3, Elipar free-light, Elipar free-light 2), and a fissure sealant (Fissurit FX) were used. Microleakage was then evaluated using a dye penetration method after thermal cycling. When the fissure sealant was polymerized with Elipar free-light and Elipar free-light 2, microleakage at 10,000 cycles was significantly increased compared with that at 5,000 cycles. In terms of comparison among the curing units, the best microleakage score was observed with Astralis 3 (p<0.05). In terms of comparison between the two bonding agents, no significant differences in microleakage score were observed (p>0.05). Further, it was concluded that in order to evaluate microleakage scores appropriately, it was necessary for specimens to be subjected to thermocycling of 10,000 times or more.