ENDO, 01/2016

Aim: The aim of the present study was to evaluate the cytotoxic effects of an epoxy resin sealer (AH Plus, Dentsply DeTrey, Konstanz, Germany) using a three-dimensional (3D) cell culture model. A conventional two-dimensional (2D) cell culture model was used as a reference technique for comparison. Materials and methods: Balb/c 3T3 fibroblasts were cultured in conventional two-dimensional cell culture and in rat tail collagen type I three-dimensional cell culture models. Then, cell cultures were incubated with elutes of freshly mixed AH Plus and with elutes of AH Plus after 7 days of mixing for 24 h. Cell viability was measured by the methyl-thiazol-diphenyltetrazolium assay. Data were statistically analysed by an independent t-test (P 0.05). Results: In all tested conditions, AH Plus exhibited cytotoxic effects; however, it was cell- and timedependent. In both conditions, AH Plus was highly cytotoxic in fresh conditions (P 0.05). Moreover, AH Plus showed high cytotoxic effects in the 2D cell culture model when compared to the 3D cell culture model (P 0.05). Conclusion: A 3D cell culture can be used as an alternative in vitro experimental model, able to provide reliable guidance on endodontic sealer toxicity under more closed conditions, related to the physiological scenario found in real-life 3D tissue microenvironments. Keywords: 3D cell culture, cytotoxicity, Epoxy Resin, root canal sealers

Aim: The purpose of this study was to evaluate the effect of repeated autoclaving on the cyclic fatigue of NRT, Revo-S and ProTaper Universal rotary Ni-Ti instruments. Methods: The instruments selected for this study (n = 120) were divided into three groups according to the type of instrument: the NRT group, the Revo-S group and the ProTaper group. Each group (n = 40) was further subdivided into four subgroups according to the number of sterilisation cycles: subgroup A, in which the instruments were used without any exposure to sterilisation cycles; subgroup B (1 cycle); subgroup C (2 cycles); and subgroup D (3 cycles). All instruments were tested in simulated canals with a 60 degree angle of curvature and a 5 mm radius. The number of cycles to failure (NCF) was calculated and statistical analysis was carried out using the ANOVA test (P ≤ 0.05) and Bonferroni's post-hoc test. Scanning electron microscope analysis was used to analyse fractured instruments. Results: Statistically, significant differences were found between the NCF mean values of the three instruments when exposed to different sterilisation cycles (P 0.001). There was no statistically significant difference between the mean NCF amongst all subgroups in the ProTaper group. However, in the Revo-S and NRT systems, a statistically significant difference was found. The scanning electron microscope analysis of the separated instruments of all groups did not show any signs of plastic deformation on the flutes near the fracture site. Conclusion: The number of sterilisation cycles has a variable effect on cyclic fatigue depending on the type of Ni-Ti instrument. Keywords: autoclaving, cyclic fatigue, rotary nickel titanium instruments

Introduction: There has been long-standing controversy on root canal treatment protocol with regard to single- and multiple-visit endodontic therapy. Amongst other factors, the question stands with regard to the amount of postoperative pain associated with single- and multiple-visit therapy. This is especially true in cases with periapical lesions. Aim: The aim of this split-mouth study was to determine the difference in postoperative pain associated with single- and multiple-visit root canal therapy and to determine if different instrumentation techniques were associated with different amounts of postoperative pain. Materials and methods: Thirty patients with bilateral apical periodontitis indicated for root canal therapy and were treated with single-visit therapy on one side and multiple-visit therapy on the other side. Their postoperative pain was measured using the visual analogue pain scale on 1, 3 and 7 days after the treatment. Out of the 30 patients, 10 were treated using the ProTaper Universal files, 10 using Hero Shaper and 10 using the Self-adjusting File. Results and conclusion: Analysis of postoperative pain in single- and multiple-visit therapy was carried out using the Student's t test and analysis of postoperative pain associated with the different instruments used in single-visit and multiple-visit, respectively, was calculated using the one-way analysis of variance. There was no statistically significant difference (P > 0.05) in postoperative pain of single and multiple root canal treatments. There was no difference in postoperative pain between the three different instrumentation techniques used (P > 0.05). Keywords: Hero Shaper, multiple-visit therapy, postoperative pain, ProTaper Universal, Selfadjusting File

In root canal therapy, radiographic imaging of the teeth and surrounding peri-radicular structures is crucial for diagnosis and management. The valuable data necessary to make a diagnosis can be lost because of the complexity of the maxillofacial skeleton, the inaccuracy of 2D radiographic images and the superimposition of surrounding anatomical structures. This case report describes a larger than normal radiolucency that was not visualised on a periapical radiograph (PA), while this was evident on the orthopantogram (OPG) and cone beam computed tomography (CBCT) images. When prescribing a radiograph, it is imperative to maximise the benefit of acquisition of information while maintaining the radiation safety for the patient; adjunct-imaging techniques such as CBCT must be considered if conventional radiographic techniques do not support clinical signs and symptoms. Keywords: CBCT, dental radiology, diagnosis, intraoral periapical radiograph, radiolucent lesions

The aim of the present report is to describe the unusual finding of mineral trioxide aggregate's (MTA) disappearance from the root-end cavity, several years after successful periapical surgery and complete wound healing. A 32-year-old male patient was referred by a general practitioner for root canal treatment of the right maxillary central and lateral incisors with a sinus track and a large periapical radiolucent lesion. After completion of the root canal treatment, endodontic surgery was performed since symptoms persisted. The retrograde cavity of the lateral incisor was sealed with MTA and the patient was monitored in the subsequent years, in order to evaluate the surgical outcome. Recall examination after 4 months revealed absence of signs and symptoms and reduction of the radiolucent lesion, indicating normal healing. After 2 years, the follow-up radiographic examination revealed further healing of the periapical lesion, with the MTA apical retrograde filling remaining in its place but with signs of disintegration. However, follow-up radiographic examination after 7 years revealed that the former radiolucent area is diminished and the root apex is completely covered by normal periodontal ligament and alveolar bone, whilst the retrograde filling is not visible at all, possibly due to disintegration. Long-term follow-up of apicoectomy cases is mandatory and further research is deemed necessary for the long-term evaluation of MTA, when in contact with periapical and periodontal tissues. Keywords: endodontic surgery, follow-up, MTA dissolution, periapical healing

The C-shaped root canal configuration is one of the most important anatomic variations of the root canal system. It is commonly reported in mandibular second molars. The C-shaped canal configuration in maxillary first molars is rare, even more so, the presence in second maxillary molars has only been reported in one case report in the literature. This paper describes the presence of unusual bilateral C-shaped configuration in maxillary second molars. Keywords: anatomic variations, cone-beam computed tomography, diagnosis, root canal therapy, tooth abnormalities

The aim of this article was to report the presentation and management of a clinical case with neurological and facial skin complications secondary to the extrusion of sodium hypochlorite and calcium hydroxide into the facial soft tissues during root canal treatment. An adult male patient was referred to the endodontic clinic after inadvertent extrusion of sodium hypochlorite and calcium hydroxide into the periapical tissues during root canal treatment. The severe clinical consequences, with particular emphasis on nerve deficit and soft tissue are discussed and its management is highlighted. Early and aggressive treatment is advocated following such incidents in order to reduce potentially serious complications. This article demonstrates the possible detrimental effect of extrusion of sodium hypochlorite and calcium hydroxide intracanal dressing into the periradicular and adjacent soft tissues. Keywords: calcium hydroxide, irrigation, nerve damage, skin scarring, sodium hypochlorite