The frequency of the extra-distal root on the mandibular first molar was 20%, and the incidence of three canals (Vertucci's type 8 classification) with separate apical foramina at the apex of the mesial root was 6%. The three-rooted variation of the mandibular first molar appears to be a genetic characteristic of an Asiatic racial background.

* Connective tissue grafts can be used to manage mucosal fenestration. * Periradicular surgery and connective tissue grafts can be used in combination.

The leakage of arsenic trioxide paste from tooth fillings has been associated with widespread necrosis of the supporting periodontal tissues. This report describes two cases of arsenic trioxide paste-induced gingival and localized alveolar bone necrosis in the mandible, following the use of arsenic trioxide paste as a pulp-devitalized agent. The first case was a 54-year-old female complaining of a painful white patch on the gingival tissue of the left mandibular second molar (tooth #37) after treatment by a private dentist. She underwent completely debridement of all necrotic soft tissue with physical saline irrigation. The gingival tissue was gradually replaced with vascular tissue and completely healed after 7 weeks. The second case was a 30-year-old female complaining of severe pain and continuous gingival bleeding from the right maxillary first bicuspid (tooth #14) following treatment by a private dentist. She finally accepted debridement of the sequestrum and necrotic alveolar bone with decortication to induce active bleeding. A partial thickness gingival flap was made to cover the wound. Four weeks later, the supporting tissues had completely healed. Arsenic trioxide paste is a cytotoxic agent and may cause harmful adverse effects on adjacent periodontium and supporting hard tissue if leakage occurs, or it is used carelessly. There is no indication for the use of arsenic trioxide paste in modern dental practice.

Background/purpose Atmospheric-pressure plasma is a new technology for biomedical applications. Utilization of an ionized gas (plasma) to achieve disinfection is an alternative sterilization technique that has become popular recently due to its safety, cost effectiveness, and superior performance to traditional methods. The purpose of this study was to evaluate the germicidal effectiveness of a low-temperature atmospheric-pressure plasma device by treating Enterococcus faecalis for different durations. Materials and methods A novel low-temperature atmospheric-pressure plasma device was developed for this study. A suspension of E. faecalis (BCRC 10789) was standardized to 10 7 colony-forming units (CFUs)/mL, as confirmed by an optical spectrophotometer. E. faecalis was first transferred and spread on 70 sterile cover glasses measuring 18 mm 2 . Each batch of 10 specimens was exposed to the low-temperature plasma device and treated for 1 minute, 2 minutes, 3 minutes, 5 minutes, 10 minutes, and 15 minutes; the specimen treated for 0 minute served as the control. The cover glasses containing plasma-treated bacteria were then immersed into 10 mL deionized distilled water and vibrated with an ultrasonic device to detach the residual fluid. Bacterial colonies were finally inoculated into Luria–Bertani agar plates and cultured at 37°C for 24 hours. The numbers of bacterial colonies were counted to evaluate the germicidal efficacy of the plasma device, and the results were expressed as CFUs. Meanwhile, field emission scanning electron microscopy was performed to observe the cell morphology of E. faecalis prior to and after plasma treatment. Results Quantitative analysis of sterilization revealed a reduction in the number of bacterial colonies with time duration. When specimens were treated for 10 minutes, colonies of E. faecalis decreased from 10 5 CFUs to 10 2 CFUs. The sterilization D -value (90% cell reduction) of experiments was 2 minutes. Conclusion The novel low-temperature atmospheric-pressure device was capable of achieving effective sterilization of E. faecalis within a 2-minute interval. Further studies are needed to validate complete inactivation, refine the laboratory-made low-temperature plasma device, and develop a new plasma-jet device, which will be superior to traditional sterilization methods and can be used in root canal environment. This novel sterilization method can also be used as a clinical reference tool.

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KEYWORDS apical seal; extended working time root canal sealers; post-space preparation; zinc oxideeeugenol sealerAbstract Background/purpose: The purpose of this study was to compare the effect of different post-space preparation time intervals on the apical sealing ability of filling material using two different extended setting time root canal sealers. Materials and methods: A total of 100 single-canal teeth were incrementally cleaned with crown-down instrumentation using K3 rotary nickeletitanium instruments and randomly divided into four groups. There were 30 teeth in the experimental groups (Groups 1e3) and 10 teeth in the control group (Group 4). We obturated the teeth using a warm gutta-percha vertical compaction technique with pulp canal sealer (Group 1), Tubli-Seal EWT (Group 2), and pulp canal sealer EWT (Group 3). We then stored all the specimens in 100% humidity at 37 C for 1 week. We used heated pluggers to create post space at three different intervals postobturation (i.e., immediately after obturation, on Day 3, and on Day 7), leaving 5-mm gutta-percha filling at the apices. We then immersed the teeth in 2% methylene blue solution for 72 hours, and finally sectioned them longitudinally into two halves. The amount of apical dye leakage was measured under a stereomicroscope. Results:The results showed no significant difference (P > 0.05) in dye leakage between the standard and extended working time root canal sealers. Apical leakage tended to increase more severely in Group 1 at the three different intervals was considered. Conclusion: Extended working time root canal sealers do not affect microleakage results using a warm gutta-percha vertical compaction technique. The sealing ability of extended working

Teeth treated by vertical compaction and injectable thermoplasticized gutta-percha techniques showed less leakage than those treated by lateral compaction. The least amount of dye leakage existed when the post space preparation was made on day 7 after root canal obturation.

Background/purpose The prevalence of pulpal calcifications was widely studied in the past. The purposes of this study were to investigate the incidence of pulpal calcifications of periodontally involved teeth in a Taiwan Chinese population using radiographic and histological examinations, and to find out any association of pulpal calcification with systemic disease and dental conditions. Materials and methods A total of 197 teeth freshly extracted because of severe periodontal destruction were collected and prepared for histological and radiographic studies of the incidence of pulpal tissue calcifications. The occurrences of calcifications were recorded based on the different types of classifications proposed by Seltzer (1972). The number of examined teeth with pulpal calcifications was calculated, and they were statistically analyzed with the Chi-square test. Results The patient population ranged in age from 16 years to 85 years. Of them, 165 (84%) were male and 32 (17%) were female. The results show that the incidence of pulpal calcifications of periodontally involved teeth was 62% in histological and 30% in radiographic examinations. The occurrences were slightly higher than that reported in some previous studies and significantly different between the two examined methods. No significant association of pulpal calcification with age and systemic disease was found. Moreover, molars were observed to have more pulpal calcifications than bicuspids and incisors statistically (P < 0.001). Conclusion The true incidence of pulpal calcifications of periodontally involved teeth is likely to be higher in histological examination because pulpal calcifications with a small diameter may not be seen on radiographs. The prevalence of pulpal calcifications was found to increase significantly in molar teeth, and the results indicated that localized calcifications occur mostly in the radicular area of the pulp tissue.