ENDO, 01/2013

tisIntroduction: The purpose of this study was to examine and compare the capacity of a mineral trioxide aggregate-based (MTA) root canal sealer with two resin self-etch root canal sealers (RealSeal SE and MetaSEAL) to induce oxidative stress and apoptosis on human fibroblasts, MRC-5 cells. Methods: For cytotoxicity testing, cells were exposed to the selected test materials then evaluated after 24 hours and 7 days using [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] MTT assay. The extent of the apoptosis was determined using propidium iodide and Annexin V-FITC double staining. Results: MTA was significantly the least toxic material at both observation times (P < 0.05) and the toxicity of RealSeal SE significantly decreased after 7 days, showing no significant difference to MTA (P < 0.05). MetaSEAL was significantly the most toxic material at both observation times (P < 0.05), and time had no significant effect on it (P > 0.05). RealSeal SE induced the highest number of apoptotic cells as well as apoptotic/necrotic cells, than both MTA and MetaSEAL. Conclusions: The cytotoxicity of RealSeal SE significantly decreased with time to show MTA's mild cytotoxicity on viable cells. While time had no effect on the toxicity of MetaSEAL, this root canal sealer displayed severe toxic effects on viable cells. Keywords: apoptosis, cytotoxicity, flow cytometry, MetaSEAL, MTA, MTT assay, oxidative stress, RealSeal SE

Aim: The aim of this study was to evaluate the in vitro efficacy of the RinsEndo device to remove the smear layer and debris in root canals. Materials and methods: Three groups of teeth (20 teeth in each) were instrumented with ProTaper files to F3 and irrigated as follows: Group 1 (control): syringe irrigation with 20 ml of 3% sodium hypochlorite (NaOCl), then a flush-flow with 2 ml 8% ethylenediaminetetraacetic acid (EDTA) solution and a final rinse with 3 ml 3% NaOCl; Group 2: irrigation by RinsEndo with the same irrigants and volumes as in Group 1; Group 3: irrigation by RinsEndo, 20 ml NaOCl then 2 ml EDTA, and the final rinse with 3 ml 3% NaOCl activated by passive ultrasonic irrigation. Teeth were split longitudinally, and the middle and apical thirds of the root walls were observed by a scanning electron microscope (SEM). Mean scores for the smear layer and debris were compared between the groups (Kruskal-Wallis and Mann-Whitney tests). Results: No significant difference was found between the smear layer scores (P > 0.05). For debris, Group 3 showed significant differences from Group 1 (P = 0.001) in the apical third. Conclusions: RinsEndo used alone did not show improved removal of debris and smear layer when compared with manual syringe irrigation. RinsEndo used in conjunction with ultrasonic irrigation removes debris better than manual irrigation. Keywords: debris, irrigation, RinsEndo, smear layer, ultrasonic

This case describes the treatment of a horizontal root fracture with dislocation of a left central maxillary incisor. A 17-year-old male patient presented himself 17 days after a sports accident without any expedient therapy. Since repositioning of the tooth failed, extraction of both tooth segments and extraoral root canal treatment of the coronal segment was conducted. The coronal fragment was replanted and fixed with a rigid splint for 4 weeks in its physiological position. Follow-up examinations from 1-6 years showed validity of treatment. An expected infraposition of the replanted tooth was recognised after 24 months. Then 6 years after the intentional replantation of the coronal tooth segment, the measurement of the infraposition was approximately 1 mm. Keywords: dislocation, horizontal root fracture, replantation, rigid splinting, root canal treatment

Aim: Dens invaginatus is a malformation of the teeth, probably resulting from an infolding of the dental papilla during tooth development. The maxillary lateral incisor is the most commonly affected tooth, though not necessarily the only one. This case report shows a successful root canal treatment of a maxillary lateral incisor with this anomaly and an associated periradicular radiolucent lesion. Methods: A 12-year-old male patient with severe pain and facial swelling was referred by his general dentist for root canal treatment of the left maxillary lateral incisor. After clinical and radiographic examinations, the diagnosis resulted in an acute alveolar abscess with a periapical lesion. Radiographic examination revealed an aberrant tooth anatomy. Results: The symptoms disappeared a few days after root canal treatment was carried out and the patient's recovery was satisfactory. Regular clinical and radiographic monitoring over the following years demonstrated complete healing of the periradicular lesion. Conclusions: Accurate diagnosis of dens invaginatus led the clinician to clean, shape and fill this complex root canal system properly in order to achieve satisfactory periradicular healing without surgical intervention. Results are supported by 5 years of follow-up examination reviews. Keywords: dens invaginatus type III, "dens in dente", endodontic treatment, maxillary lateral incisor

Aim: The aim of this in vitro study was to determine if accelerating the setting time of mineral trioxide aggregate, without altering its physical properties, would improve clinical efficiency. This involved examining whether the setting expansion of ProRoot MTA (Dentsply Tulsa Dental Specialities, Tulsa, OK, USA) was affected by adding an accelerant, 5% calcium chloride (CaCl2) and to investigate the setting expansion of a Portland cement clinker (PCC) mixed with a super plasticiser, 5.0 µl Glenium 7710 (SP). Materials and methods: Thirty-six samples were randomly divided into six groups: Groups 1 and 2 - grey and white MTA (GMTA, WMTA) prepared according to manufacturer's directions; Groups 3 and 4 - GMTA and WMTA mixed with water and accelerant; Group 5 - Type I Portland cement (PC) mixed with water; Group 6 - PCC mixed with water and SP. Each sample was vibrated into a 10 mm cylindrical mould and submerged in Hank's Balanced Salt Solution to simulate a physiologic environment. A linear variable displacement transformer dilatometer, accurate to 0.002%, measured setting expansion over a 24-hour period. A one-way ANOVA and a Tukey post hoc test (α = 0.05) were used to analyse the data. Results: A highly significant difference in expansion was found between the GMTA groups and all other groups (P = 0.001). There were no significant differences between the grey accelerated and nonaccelerated MTA groups, or between the white accelerated and non-accelerated MTA groups. The PCC with SP expanded significantly less than the GMTA groups but similarly to the WMTA groups. Conclusion: The setting expansion of MTA was not affected by adding an accelerant. Keywords: accelerant, calcium chloride, expansion, MTA

Objective: To evaluate the percentage of filled area of oval-shaped root canals. Materials and methods: Thirty-four mandibular incisors, 42 mandibular premolars and 50 mandibular molars (distal roots only) (n = 126 teeth) were resected 1 and 5 mm from the apex and the cross sections evaluated. All treatments were performed by undergraduate students, who were not aware of the cross-sectional shape of the canal. Obturation was performed using the lateral compaction technique of gutta-percha with sealer. Results: The findings demonstrated that although all treated root canals were oval-shaped at 5 mm short, the vast majority of them were round at the 1-mm level. The percentage of the total filling area at the 1-mm level was 79% (range: 20-100%) for incisors, 89% (range: 46-100%) for premolars, and 97% (range: 60-100%) for the molar distal root. Correspondent values for the 5-mm level were 92% (range: 52-100%) for incisors, 99% (range: 86-100%) for premolars, and 96% (range: 78-100%) for molars. Gutta-percha was always the major component of the filling mass. At the 1-mm level, the mean proportion of gutta-percha ranged from 66% to 79%, while at the 5-mm level it ranged from 62.5% to 76%. Conclusion: The findings confirmed that the quality of the root canal filling is compromised in ovalshaped canals, and suggested that this may be more likely a limitation of the technique than a matter of the operator's expertise. Keywords: endodontic treatment, gutta-percha, lateral compaction technique, oval root canals, pre-clinical training, root canal filling

Aim: This study was undertaken to determine the antimicrobial and antifungal effect of BioPure MTAD, Metapex and aztreonam against Enterococcus faecalis and Candida albicans. Materials and method: The testing of the antimicrobial and antifungal efficacy of selected medicaments against Enterococcus faecalis and Candida albicans was done by the agar disc-diffusion method. Pre-sterilised Whatman paper discs, 6 mm in diameter and soaked with the test solution, were prepared and placed onto the previously seeded agar petri plates. Each plate was incubated at 37°C for 48 hours. A zone of inhibition was recorded for each plate and the results were analysed statistically. Saline and ethanol were used as control groups in this study. Results: BioPure MTAD was effective against all the test microorganisms with a substantial zone of inhibition. Saline and ethanol used as controls were ineffective. Metapex and aztreonam showed a significantly larger average zone of inhibition against E. faecalis, but were not effective against C. albicans. Conclusions: BioPure MTAD was found to be superior in its antimicrobial and antifungal abilities compared with the other irrigants used. When Metapex and aztreonam were compared, Metapex showed a greater antimicrobial effect, but both failed to show any antifungal effect. Keywords: aztreonam, Biopure MTAD, C. albicans, E. faecalis, Metapex

Aim: To evaluate the influence of curvature location along two artificial canals on the cyclic fatigue (CF) of two rotary instruments (Mtwo 35 and Revo-S AS35) by assessing the number of cycles to fracture (NCF) and the morphologic characteristics of the fractured instruments. Methodology: The instruments were tested in artificial curved canals made by milling grooves in stainless steel blocks, with the following measurements: 1.5 mm (width), 20 mm (total length), 3.5 mm (depth), and a U-shaped bottom. In order to enable comparisons, the parameters of curvature varied in two different designs: the canal A curvature was located at the apical portion of the canal, and the canal B curvature was located in the middle of the canal length. All instruments were rotated until fracture and the NCF was recorded. Data were analysed by Student's t test. The fractured surfaces and helical shafts of the instruments were analysed by scanning electron microscopy (SEM). Results: Canals A and B had statistically significantly different (P < 0.05) NCF values, with canal B resulting in the lowest NCF values. Plastic deformation of the shafts was not detected in any of the instruments tested. The fractured surfaces displayed morphological characteristics of ductile mode fracture. Conclusions: Placement of the curvature in the middle of the canal length reduced the NCF of the instruments tested. Keywords: canal curvature geometry, cyclic fatigue, rotary nickel-titanium instruments

Introduction: The aim of this study was to investigate the effect of instrument material, taper and degree of root canal curvature, and the interaction between these factors on the cyclic fatigue of rotary nickel-titanium instruments. Materials and methods: Two types of rotary NiTi root canal instruments made from different materials were tested: ProFile GT and Profile GT Series X (both Dentsply Tulsa Dental, Tulsa, OK, USA). For each system, 60 instruments of similar size (size 30) were divided into three equal groups according to instrument taper (0.04, 0.06, or 0.08). Then each group was tested for cyclic fatigue resistance in simulated root canals exhibiting 5 mm radius of curvature, and either a 45- or 60-degree angle of curvature. The number of cycles to failure were analysed by one-way analysis of variance (ANOVA), followed by Tukey-Kramer multiple-comparison post hoc test. Then three-way analysis of variance was performed to assess the interaction between instrument material, taper and canal curvature on cyclic fatigue. Results: The results of the one-way ANOVA revealed that there was a significant effect for each of the studied variables on cyclic fatigue. The results of the three-way ANOVA revealed that the interaction between the variables significantly but unequally affected cyclic fatigue. Conclusions: The most effective variable was the degree of root canal curvature, followed by instrument taper, and finally the material used for manufacturing of the instruments. Keywords: cyclic fatigue, root canal curvature, rotary nickel titanium instruments, taper

Introduction: The aim of this study was to evaluate the dentine wettability of different endodontic irrigation solutions by measuring the contact angle. Methods: Fifteen roots of recently extracted mandibular premolars were used, and cementum was eliminated. Root canals were instrumented according to the step-back technique using distilled water as an irrigant. The apical and coronal thirds of the roots were eliminated and the middle thirds were transversally sectioned. The 30 segments were embedded in acrylic resin and ground smooth and polished using 400-1200 grit papers. The dentine segments were randomly divided into six groups according to the irrigating solution they were put into contact with at 37°C for 5 mins: distilled water, 1% sodium hypochlorite, 1% citric acid, 17% EDTA, 1% citric acid + 1% sodium hypochlorite, 17% EDTA + 1% sodium hypochlorite. Then a 3 µl drop of distilled water was laid on each dentine surface with a micro-syringe and images were immediately captured with a super steady shot camera and digitalised. The contact angles were measured using ruler software. Results were analysed using one-way ANOVA and Tukey's test. Results: The contact angles were significantly reduced after pre-treatment of the dentine samples with 17% EDTA or 1% citric acid (P < 0.05), either alone or in combination with 1% sodium hypochlorite. The latter showed no significant difference compared to the control (P > 0.05). Conclusion: It was discovered that 1% citric acid and 17% EDTA, alone or in combination, increased the surface free energy of dentine. Keywords: citric acid, contact angle, EDTA, sodium hypochlorite, wettability