Retrospective study of endodontic treatment performed by undergraduate students using reciprocating instrumentation and single-cone obturation.

OBJECTIVES: The aim of this cross-sectional retrospective study was to evaluate radiographically the technical quality of root canal treatment performed by undergraduate students using reciprocating NiTi instrumentation and single-cone obturation. METHODS: Endodontic treatment on 1102 teeth performed by undergraduate students from the School of Dentistry of the University of Santa Cecilia (Brazil) was evaluated. All root canal preparations were performed using Reciproc files and were irrigated with 1% NaOCl. The root canal was filled with gutta-percha, along with AH Plus sealer, using the single-cone obturation technique. The technical quality of the root canal treatment was evaluated based on immediate postoperative radiographs. Distance between the end of the filling and the radiographic apex, the filling density, and the taper of the root filling was assessed. Inter-examiner agreement statistic (Kappa) and Chi-square statistic test were used for statistical evaluation of the results. Differences were considered statistically significant when p < 0.05. RESULTS: Anterior teeth, maxillary premolars, and molars presented better results than mandibular premolars and molars (p < 0.05). Mandibular premolars presented a high incidence of a short length of obturation (33.34%) and mandibular molars presented a high incidence of overfilling (6.55%). The majority of the treatment analyzed (62.46%) fulfilled all the criteria showing acceptable working length, taper, and density of obturation. Instrument fractures occurred in eighteen root canals (0.81%). CONCLUSIONS: The use of NiTi reciprocating instruments with the single-cone obturation technique provided an acceptable quality of endodontic treatment in the majority of the cases performed by undergraduate students.

Effects of risedronate on osteoblastic cell cultures.

OBJECTIVE: Bisphosphonates (BPs) have been widely used in the treatment of bone disorders due to their ability to modulate bone turnover. The biological mechanisms through BFs exert their effects on osteoclasts are well established. However, the role of BFs on the osteoblasts is controversial. The present study aimed to evaluate the effects of risedronate on osteoblastic cells. DESIGN: MC3TE-E1 cells were exposed to risedronate at 0, 10(-8), 10(-6), 10(-4), and 10(-3)M. The following parameters were assayed: (1) cell proliferation by hemocytometer counting after 24, 48 and 72h, (2) cell viability by MTT assay after 24, 48 and 72h, (3) Type I Collagen quantification by ELISA after 24, 48 and 72h, (3) alkaline phosphatase activity after 7 and 10days and (4) matrix mineralization after 14days. RESULTS: After 24h, risedronate did not affect both cell proliferation and viability (p>0.05). However, after 48 and 72h, a decrease in cell proliferation and viability was detected in osteoblastic cultures exposed to risedronate at 10(-4) and 10(-3)M (p<0.05). After 48 and 72h, Type I Collagen synthesis was stimulated by risedronate at 10(-4)M (p<0.05). High levels of ALP activity were detected in cultures exposed to risedronate at 10(-4)M after 7 and 10days (p<0.05). After 14day, high calcium content was observed in cultures exposed to risedronate at 10(-4)M (p>0.05). CONCLUSION: These results indicated that risedronate can promote osteoblast differentiation.