Examination of gutta-percha cones for microbial contamination during chemical use

OBJECTIVE: The aim of this study was to evaluate the degree of microbial contamination in packaged gutta-percha cones before and during use in clinical conditions. MATERIAL AND METHODS: Sealed packages of #15-40 gutta-percha cones were opened under aseptic laboratory conditions. Two gutta-percha cones from each size were randomly drawn and added to tubes containing glass beads and 750 µL of saline. The tubes were vortexed, serially diluted and samples of 250 µL were cultured on agar plates. The plates were incubated at 37ºC for 3 days and colonies were counted. The initially sampled packages were distributed to 12 final year dental students. The packages were collected at the end of the first and the third clinical practice days and sampled as described above. RESULTS: Baseline microbial counts did not exceed 3 CFU. At the end of the first and the third day, additional contamination was found in five and three of the packages, respectively. The ratio of contaminated packages at the first day and the third day was not significantly different (z-test; p >; 0.05). The numbers of microorganisms cultured at the first day (8 ± 9.9 CFU) and the third day (4.5 ± 8.3 CFU) were not significantly different (Wilcoxon signed-rank test; p >; 0.05). No significant correlation was found between the number of filled root canals and cultured microorganisms at either the first day (Spearman's rho; r = 0.481, p = 0.113) or the third day (r = -0.034, p = 0.917). CONCLUSIONS: Gutta-percha cones taken directly from manufacturer's sealed package harbored microorganisms. Clinical use of the packages has been found to be associated with additional contamination of the gutta-percha cones. The counts of cultured microorganisms did not correlate well with the number of filled root canals

THE EFFECT OF BOND STRENGTH AFTER LASER APPLICATION OF ADHESIVES APPLIED ON THE CORONAL AND ROOT CANAL DENTIN

Er:YAG lazer, diş hekimliğinde frezlerin yerine kullanılmaya çalışılsa da adezivlerin dentine bağlanmasında frez preparasyonları kadar iyi sonuç vermemektedir. Bu çalışmada, Er:YAG lazerle prepare edilmiş dentin yüzeylerine uygulanan 4 farklı adezivin (Scotchbond Multi- Purpose, Adper Single Bond, Clearfil SE ve Clearfil S3) Nd:YAG lazer uygulanarak ısıtılmasıyla, koronal dentine bağlanma dayanımlarında bir farklılık olup olmadığının incelenmesi ve frezle prepare edilmiş yüzeylerdeki bağlanma dayanımlarıyla kıyaslanması amaçlanmıştır. Çalışmada ayrıca post boşluklarına uygulanan adezivlerde aynı işlemin yarar sağlayıp sağlamadığı araştırılmıştır. Araştırmanın birinci bölümünde, koronal dentin, tungsten karbid frez veya Er:YAG lazer ile hazırlandı. Er:YAG lazer grubundaki dişlerin bir kısmına uygulanan adezivler polimerizasyondan önce Nd:YAG lazer (100 mJ, 10 Hz) uygulanarak ısıtıldı. Grupların bağlanma dayanımı mikrogerilim deneyiyle incelendi. Frez grupları beklendiği gibi Er:YAG lazer gruplarından iyi bulundu. Nd:YAG lazer uygulamasının bütün adezivlerde bağlanma dayanımını arttırdığı, nominal olarak daha düşük değerler elde edilse de frez gruplarıyla aradaki istatistiksel anlamlı farklılığın ortadan kalktığı saptandı. Araştırmanın ikinci bölümünde, kök kanalı prepare edildi ve dolduruldu. Post boşluğu bir post frezi ile hazırlandı. Daha sonra post boşluğuna uygulanan adezivin üzerine polimerizasyondan önce Nd:YAG lazer uygulandı. Bağlanma dayanımı push-out deneyi ile incelendi. Nd:YAG lazer uygulamasının yine tüm adezivlerde bağlanma dayanımını arttırdığı bulundu. SEM incelemelerinde kök ve koronal dentinde adeziv üzerine polimerizasyondan önce Nd:YAG lazer uygulamasının adezivin tübül penetrasyon derinliğini arttırdığı gözlendi. Bu çalışmanın sonunda adezivin ısısının arttırılmasının dentine bağlanma dayanımını geliştirdiği bulundu.Er:YAG laser can be used instead of air-turbine for cavity preparation in dentistry. However, the bond strength achieved after Er:YAG preparation is not as good as that achieved after bur preparation. In this study the effect of Nd:YAG-treatment on the adhesive applied onto Er:YAG prepared coronal dentin was investigated. The bond strength achieved so was compared with that achieved after bur preparation. Also, the effect of Nd:YAG-treatment on adhesive was tested in the root canal post space. In the first part, coronal dentin was prepared either with tungsten carbid bur or Er:YAG laser. Then, adhesive (Scotchbond Multi- Purpose, Adper Single Bond 2, Clearfil SE and Clearfil S3) was applied onto the dentin. In some of the teeth in Er:YAG preparation, the adhesive was heated with Nd:YAG lasing (100mJ, 10Hz). The bond strength as evaluated using the microtensile test. The bur group, as expected, revealed higher bond strength. Nd:YAG-treatment increased the bond strength in all adhesive systems. While bond strength values were stil lower in the Nd:YAG-treated group, but statistically significant difference was not found between the Nd:YAG-treated and bur groups. In the second part, root canal was prepared and obturated. A post space was then prepared using a post dril. The adhesive was applied into the post space and heated with Nd:YAG lasing prior to polimerization in some of the teeth. The bond strength was evaluated using the push-out test. Again, Nd:YAG application was found to increase the bond strength in all adhesive systems. SEM analysis showed that coronal or root canal dentinal tubule penetration was greater when the adhesive was treated with Nd:YAG laser prior polimerization. As conclusion, heating of adhesive using Nd:YAG laser was found to develop the bond strength on coronal and root canal dentin

The evaluation of the surface micro-hardness values in different depth of resin blocks

Objective: Computer-aided design and manufacturing technology has shown great improvement in dentistry since the 1980s. This technology is based on a one-stage restoration using prefabricated blocks. Two main types of materials are used during CAD / CAM indirect restorations:  glass-ceramic / ceramic and resin composite. CAD / CAM resin blocks are polymerized under high temperature and pressure. Polymerization depth affects the surface hardness of composite resins. When preparing a restoration, different depth layers of the resin block are used. The aim of this study is to show that adequate polymerization is achieved in each layer of the resin blocks and that the hardness of each layer is the same. Two composite resin block materials and one hybrid resin block material were included in this study. Material and method: The CAD/CAM block materials evaluated in this study were Cerasmart, Lava  and Vita Enamic Square specimens (n=5/material) of approximate dimensions 10×10×2 mm blocks were sectioned (5 slices/block) from commercially available CAD-CAM materials using a diamond saw (exakt 300 cl Apparatebau, Norderstedt, Germany) with water cooling. All specimens were abraded followed by 500,1200,2500 grid using SiC abrasive paper (exakt 400 cs Apparatebau, , Norderstedt, Germany). After storage in distilled water at 37 °C for 24 hours the Knoop hardness test was performed using a hardness testing machine (Buehler MMT 3 digital micro hardness tester, Lake Bluff, IL, USA) using a load of 500 gf and a loading time of 10s. Results: The material with the highest hardness number was Vita Enamic block, whereas the lowest numbered group was the Cerasmart. The rank order of surface hardness was as follows: Vita Enamic> Lava Ultimate >Cerasmart. Conclusion: The hardness measurements of the layers of blocks were similar

Effect of irrigation technique for removal of triple antibiotic paste on bond strength of MTA to root dentin

Abstract This study evaluated the bond strength of mineral trioxide aggregate (MTA) to root canal dentin after the performance of various irrigation procedures to remove triple antibiotic paste (TAP). A total of 56 single-rooted human mandibular premolars were instrumented using a rotary system to size 40 and divided randomly into a control group (no intracanal dressing) and three experimental groups (TAP application for 28 days). TAP was then removed by rinsing with 10 mL 2.5% NaOCl using three irrigation systems (Vibringe sonic irrigation, CanalBrush, and syringe irrigation). The coronal and middle parts of root canals were then obturated with MTA. After storage for 1 week, each specimen was embedded in an acrylic block and sectioned horizontally (2-mm-thick slices) at two levels (coronal and middle). Bond strength of MTA to root canal dentin was assessed in 28 samples per group via push-out test using a universal testing machine. Data from the four groups were compared using one-way analysis of variance. Tukey’s test was used for multiple comparisons. Push-out bond strength values were significantly higher in the control and Vibringe groups than in the CanalBrush and syringe irrigation groups (p < 0.001). TAP removal from root canals with the Vibringe irrigation system may increase the push-out bond strength of MTA compared with the use of the CanalBrush or syringe irrigation

Antibacterial Efficacy of Calcium Hypochlorite with Vibringe Sonic Irrigation System on Enterococcus faecalis: An In Vitro Study

Aim. The purpose of this study was to compare the in vitro efficacy of calcium hypochlorite (Ca[OCl]2) and sodium hypochlorite (NaOCl) associated with sonic (Vibringe) irrigation system in root canals which were contaminated with Enterococcus faecalis. Material and Methods. The root canals of 84 single-rooted premolars were enlarged up to a file 40, autoclaved, inoculated with Enterococcus faecalis, and incubated for 21 days. The samples were divided into 7 groups according to the irrigation protocol: G0: no treatment; G1: distilled water; G2: 2.5% NaOCl; G3: 2.5% Ca(OCl)2; G4: distilled water with sonic activation; G5: 2.5% NaOCl with sonic activation; and G6: 2.5% Ca(OCl)2 with sonic activation. Before and after decontamination procedures microbiological samples were collected and the colony-forming units were counted and the percentages of reduction were calculated. Results. Distilled water with syringe irrigation and sonic activation groups demonstrated poor antibacterial effect on Enterococcus faecalis compared to other experimental groups (p<0.05). There was no statistically significant difference between syringe and sonic irrigation systems with Ca(OCl)2 and NaOCl. Conclusion. The antimicrobial property of Ca(OCl)2 has been investigated and compared with that of NaOCl. Both conventional syringe irrigation and sonic irrigation were found effective at removing E. faecalis from the root canal of extracted human teeth

Examination of gutta-percha cones for microbial contamination during chemical use

OBJECTIVE: The aim of this study was to evaluate the degree of microbial contamination in packaged gutta-percha cones before and during use in clinical conditions. MATERIAL AND METHODS: Sealed packages of #15-40 gutta-percha cones were opened under aseptic laboratory conditions. Two gutta-percha cones from each size were randomly drawn and added to tubes containing glass beads and 750 µL of saline. The tubes were vortexed, serially diluted and samples of 250 µL were cultured on agar plates. The plates were incubated at 37ºC for 3 days and colonies were counted. The initially sampled packages were distributed to 12 final year dental students. The packages were collected at the end of the first and the third clinical practice days and sampled as described above. RESULTS: Baseline microbial counts did not exceed 3 CFU. At the end of the first and the third day, additional contamination was found in five and three of the packages, respectively. The ratio of contaminated packages at the first day and the third day was not significantly different (z-test; p > 0.05). The numbers of microorganisms cultured at the first day (8 ± 9.9 CFU) and the third day (4.5 ± 8.3 CFU) were not significantly different (Wilcoxon signed-rank test; p > 0.05). No significant correlation was found between the number of filled root canals and cultured microorganisms at either the first day (Spearman's rho; r = 0.481, p = 0.113) or the third day (r = -0.034, p = 0.917). CONCLUSIONS: Gutta-percha cones taken directly from manufacturer's sealed package harbored microorganisms. Clinical use of the packages has been found to be associated with additional contamination of the gutta-percha cones. The counts of cultured microorganisms did not correlate well with the number of filled root canals