Heloisa Gusman

Scanning Electron Microscopic Investigation of the Effectiveness of Phosphoric Acid in Smear Layer Removal When Compared with EDTA and Citric Acid

INTRODUCTION The smear layer adheres to dentinal surface, thus occluding the dentinal tubules. Because this layer disfavors the penetration of irrigant solutions and root canal fillings, it should be removed. The aim of this study was to compare the effectiveness of 37% phosphoric acid with that of 17% EDTA and 10% citric acid in the removal of smear layer. MATERIALS AND METHODS Fifty-two maxillary single-rooted human canines were accessed and instrumented. Between each instrument used, the canals were irrigated with sodium hypochlorite. After instrumentation, the teeth were irrigated with distilled water and then divided into groups according to the time and substances employed. The substances used were 17% EDTA, 10% citric acid, and 37% phosphoric acid solution and gel. The experimental time periods were of 30 seconds, 1 minute, and 3 minutes. The samples were prepared and observed by means of scanning electron microscopy. Three photomicrographs (2,000×) were recorded for each sample regarding the apical, middle, and cervical thirds. A score system was used to evaluate the images. RESULTS None of the substances analyzed in this study was effective for removing the smear layer at 30 seconds. In the 1-minute period, the phosphoric acid solution showed better results than the other substances evaluated. In the 3-minute period, all the substances worked well in the middle and cervical thirds although phosphoric acid solution showed excellent results even in the apical third. CONCLUSIONS These findings point toward the possibility that phosphoric acid solution could be a promising agent for smear layer removal.

Ex vivo antimicrobial efficacy of the EndoVac® system plus photodynamic therapy associated with calcium hydroxide against intracanal Enterococcus faecalis

AIM To evaluate the ex vivo efficacy of the EndoVac system and photodynamic treatment (PDT) as adjuncts to chemomechanical debridement associated with calcium hydroxide (CaOH2 ) in reducing the levels of intracanal Enterococcus faecalis. METHODOLOGY One hundred and twenty-five sterile premolar teeth were conventionally accessed, prepared and then contaminated with E. faecalis (ATCC 29212) for 30 days. Teeth were randomly divided into 4 groups: Control (chemomechanical debridement with conventional irrigation); Endovac (chemomechanical debridement with EndoVac system); PDT (chemomechanical debridement with conventional irrigation and PDT) and Endovac+PDT (chemomechanical debridement with EndoVac and PDT). The irrigants used in all groups were 5.25% sodium hypochlorite and 17% EDTA. After treatment, an intracanal dressing (CaOH2 ) was applied in all canals for 7 days. Samples were obtained before (T1) and after the therapeutic procedures (T2) and, after intracanal medication (T3), plated onto BHI media and incubated (37 °C, 48 h) to determine the colony-forming units (CFU mL(-1) ). RESULTS The overall mean cell counts (CFU mL(-1) ) of E. faecalis were high at the initial contamination (T1). A significant reduction (P < 0.05) of E. faecalis mean counts was observed in all groups from baseline (T1) to both post-therapy samplings (T2 and T3); no differences amongst the groups were detected. No significant change in bacterial counts from T2 to T3 was detected. CONCLUSION The adjunctive use of the EndoVac system and the photodynamic treatment, in combination or not, was as effective as the conventional chemomechanical debridement associated with CaOH2 on reducing the counts of intracanal E. faecalis.

A Comparative Study on the Frequency, Location, and Direction of Accessory Canals Filled With the Hydraulic Vertical Condensation and Continuous Wave of Condensation Techniques

The present study compared the frequency, location, and direction of accessory canals filled with two different filling techniques. Sixty-four mandibular first molars were accessed, prepared, and divided into two groups of 32 teeth each. The teeth from group A and group B were filled using the hydraulic vertical condensation technique and the continuous wave of condensation technique, respectively. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators. There was no significant difference (t test, p < 0.05) between the two groups in relation to the total number of filled ramifications. Moreover, there was no significant difference among the three thirds of the roots in relation to the number of filled ramifications (analysis of variance, p < 0.05). The filled ramifications were more frequently detected toward lingual, buccal, distal-lingual, and distal-buccal directions. It was concluded that the two filling techniques are not different in relation to the frequency, location, and direction of the ramifications filled.

Effect of disinfectant solutions on gutta-percha and resilon cones.

The aim of this study was to evaluate the effects of the 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), and MTAD solutions on the surface of gutta‐percha and Resilon cones by using atomic force microscopy (AFM). Accessory cones were washed and dried. The cones were randomly divided into six groups: gutta‐percha immersed in NaOCl, CHX, and MTAD, and Resilon immersed in NaOCl, CHX, and MTAD. AFM images of the same area were made in different periods of time. JPK™ Image Processing Software was used to evaluate the images. The parameters used to evaluate the changes were RMS and line profiles. No statistically significant change was observed in the RMS values. The line profiles detected changes only for gutta‐percha surfaces after immersion in NaOCl and MTAD solutions. In conclusion, 5.25% NaOCl and MTAD are associated with local changes in surface roughness of gutta‐percha cones. No change was observed when 2% CHX was used. The use of all tested solutions did not produce any changes on Resilon surface. Microsc. Res. Tech. 75:791–795, 2012.

The use of auxiliary devices during irrigation to increase the cleaning ability of a chelating agent

Objectives This study investigated the cleaning ability of ultrasonically activated irrigation (UAI) and a novel activation system with reciprocating motion (EC, EasyClean, Easy Equipamentos Odontológicos) when used with a relatively new chelating agent (QMix, Dentsply). In addition, the effect of QMix solution when used for a shorter (1 minute) and a longer application time (3 minutes) was investigated. Materials and Methods Fifty permanent human teeth were prepared with K3 rotary system and 6% sodium hypochlorite. Samples were randomly assigned to five groups (n = 10) according to the final irrigation protocol: G1, negative control (distilled water); G2, positive control (QMix 1 minute); G3, QMix 1 minute/UAI; G4, QMix 1 minute/EC; G5, QMix 3 minutes. Subsequently the teeth were prepared and three photomicrographs were obtained in each root third of root walls, by scanning electron microscopy. Two blinded and pre-calibrated examiners evaluated the images using a four-category scoring system. Data were statistically analyzed using Kruskal-Wallis and Dunn tests (p < 0.05). Results There were differences among groups (p < 0.05). UAI showed better cleaning ability than EC (p < 0.05). There were improvements when QMix was used with auxiliary devices in comparison with conventional irrigation (p < 0.05). Conventional irrigation for 3 minutes presented significantly better results than its use for 1 minute (p < 0.05). Conclusions QMix should be used for 1 minute when it is used with UAI, since this final irrigation protocol showed the best performance and also allowed clinical optimization of this procedure.

Effect of photodynamic therapy and non-thermal plasma on root canal filling: analysis of adhesion and sealer penetration

Abstract Objective The aim of this study was to evaluate the effect of photodynamic therapy (PDT) and non-thermal plasma (NTP) on adhesion and sealer penetration in root canals. Material and Methods Sixty single-rooted premolars were used. The teeth were prepared using a crown-down technique. NaOCl and EDTA were used for irrigation and smear layer removal, respectively. The root canals were divided into three groups: control, PDT, and NTP. After treatments, the roots were filled using gutta-percha and either AH Plus (AHP) or MTA Fillapex (MTAF) sealers. Samples were sectioned at 4, 8, and 12 mm from the apex (1-mm slices)and analyzed by the push-out bond strength test (adhesion) and confocal laser scanning microscopy (sealer penetration). Data were statistically evaluated using Kruskal-Wallis, Dunn’s, and Spearman’s tests. Results Regarding AHP, bond strength was similar in the NTP group and in the control group, but significantly lower in the PDT group. As to MTAF, both therapies showed lower values than the control group. In the confocal analysis of AHP, maximum and mean penetration, and penetrated area were statistically higher in the control group than in the PDT and NTP groups. Penetrated perimeter was similar among groups. Regarding MTAF, all parameters yielded better results in the NTP than in the control group. The PDT and control groups showed similar results except for penetrated area. Conclusion PDT and plasma therapy affected the adhesion and sealer penetration of root canals filled with AH Plus and MTA Fillapex and there is no positive correlation between adhesion and sealer penetration.

Influence of Heat Treatment of Nickel-Titanium Rotary Endodontic Instruments on Apical Preparation: A Micro-Computed Tomographic Study

INTRODUCTION The aim of this study was to make a 3-dimensional comparison of the canal transportation and changes in apical geometry using micro-computed tomographic imaging after canal preparation with K3 (SybronEndo, Orange, CA) and K3XF (SybronEndo) file systems. METHODS Twenty-eight mandibular molars were randomly divided into 2 groups according to the rotary system used in instrumentation: K3 or K3XF. The specimens were scanned by micro-computed tomographic imaging before and after instrumentation. Images before and after instrumentation from each group were compared with regard to canal volume, surface area, and structure model index (SMI) (paired t test, P < .05). After instrumentation, the canals from each group were compared regarding the changes in volume, surface area, SMI, and canal transportation in the last 4 apical mm (t test, P < .05). RESULTS Instrumentation with the 2 rotary systems significantly changed the canal volume, surface area, and SMI (P < .05). There were no significant differences between instrument types concerning these parameters (P > .05). There were no significant differences between the 2 groups with regard to canal transportation in the last 4 apical mm (P > .05). CONCLUSIONS Both rotary systems showed adequate canal preparations with reduced values of canal transportation. Heat treatment did not influence changes in root canal geometry in the apical region.

Effects of auxiliary device use on smear layer removal

This study evaluated the effects of different auxiliary irrigation devices on smear layer removal with a chelating solution (QMix). Fifty single-rooted permanent human teeth were shaped with a sequence of nickel-titanium instruments. A 2% chlorhexidine gel was used as a chemical auxiliary substance during preparation. Samples were assigned to five groups (n = 10 each) according to final irrigation protocol, namely, distilled water (control group), QMix 1 min, QMix + passive ultrasonic irrigation (PUI), QMix + plastic endodontic finishing file (EC), and QMix 3 min. Teeth were prepared and evaluated by scanning electron microscopy, and three photomicrographs (magnification, 1,000×) were obtained for each root third. Two blinded and precalibrated evaluators analyzed and scored the images, and the data were statistically analyzed by the Kruskal-Wallis and Dunn tests (P < 0.05). Groups were ranked according to the extent of smear layer removal. The total area of the root canal walls and apical root thirds was calculated, and the groups ranked PUI > EC = QMix 3 min > QMix 1 min > control. QMix 1 min was effective for smear layer removal only when used with auxiliary devices, and QMix + passive ultrasonic irrigation yielded the best results, particularly for the apical third.(J Oral Sci 58, 561-567, 2016).

Effectiveness of three methods for evaluating root canal anatomy of mandibular incisors.

This study compared the effectiveness of clinical observation, clinical microscopic observation, and tooth-clearing technique in determining the number of canals in mandibular incisors. Root canal ramifications were also analyzed. Using clinical and microscopic analyses, we determined the number of canal entrances in 277 mandibular incisors. In addition, tooth-clearing technique was used to determine the number of canals and frequency of ramifications in the samples. The kappa coefficient was used to compare the different methods with regard to frequency of canals. Most teeth had one canal entrance. The proportion of teeth with two canals was 23.5% by tooth-clearing analysis, 5.8% by clinical microscopy, and 1.1% by clinical analysis. A large number of samples had some type of ramification (40.1%), and most ramifications were present in teeth with two canals. The most frequent ramification was lateral canals (8.3%). Clinical microscopy improved identification of a second canal in mandibular incisors. However, it did not identify second canals in all teeth with two canals. (J Oral Sci 58, 347-351, 2016).

Antimicrobial efficacy of the EndoVac system plus PDT against intracanal Candida albicans: an ex vivo study.

This study evaluated the ex vivoantimicrobial efficacy of the EndoVac system and the photodynamic therapy (PDT) associated with chemomechanical debridement (CMD) and intracanal medication on Candida albicans. Seventy-eight sterile premolars were contaminated withC. albicans (ATCC 21433) for 30 days. The teeth were randomly assigned into four groups: Control (CMD with conventional irrigation); Endovac (CMD with EndoVac system); PDT (CMD with conventional irrigation and PDT); and Endovac + PDT (CMD with EndoVac and PDT). After the therapies, intracanal dressing (calcium hydroxide) was applied to all teeth for seven days. Samples were obtained before (T1) and after the therapeutic procedures (T2), and after intracanal medication (T3), plated onto BHI agar and incubated (37°C, 48 h) to determine the colony-forming units (CFU)/mL. The overall mean level ofC. albicans at baseline was relatively high (1.85 x 106 ± 2.7 x 106 CFU mL-1). A significant reduction of C. albicans(p < 0.05) was observed over time (T1 to T2 and T1 to T3) in all groups. An additional significant reduction from T2 to T3 was observed only in the Endovac group (p < 0.05). No differences in mean reduction of C. albicans were observed among groups. However, the Endovac group presented the lowest mean counts of C. albicans at T3, whereas the PDT group had the highest counts of this microorganism (p < 0.05). The EndoVac system of irrigation/aspiration associated with CMD was the most effective therapeutic protocol for reducing intracanal levels of C. albicans. PDT showed a very limited efficacy against this species.