Management of complicated crown-root fractures using intentional replantation: two case reports.

The management of complicated crown-root fractures is a challenge. Intentional replantation with 180° rotation may be a useful procedure to overcome this problem. In Case 1, a 23-year-old woman with complicated crown-root fractured teeth #11, #21, and #22 was referred for treatment. All fractured teeth were extracted, rotated 180°, and replanted in a slightly extruded position. After 3 months, root canal treatment was completed and the final restorations fabricated. At the 18-month follow up, the patient was asymptomatic, the tooth was functional, and no root resorption was observed radiographically. At the 90-month follow up, slight cervical root resorption of tooth #11 was noted. In Case 2, a 27-year-old woman with a crown-root fractured tooth #21 was referred for treatment. Despite immediate repositioning of the coronal fragment and a 2-week stabilization with a wire splint, the coronal fragment remained separated from the apical tooth segment. The apical segment was extracted, rotated 180°, and replanted in a slightly extruded position. After 1 and 4 weeks, the root canal treatment was completed and the final restoration fabricated, respectively. At the 24-month follow up, the patient was asymptomatic and apical healing was completed.

Effects of simvastain and enamel matrix derivative on Portland cement with bismuth oxide-induced growth and odontoblastic differentiation in human dental pulp cells.

INTRODUCTION: We previously reported that bismuth oxide containing Portland cement (BPC) showed similar biocompatibility to Portland cement (PC) in periodontal ligament cells. However, the bioactivity of simvastatin and Emdogain (Biora AB, Malmö, Sweden) on BPC was not reported. The aim of this study was to evaluate the effects of simvastatin and Emdogain on BPC compared with mineral trioxide aggregate (MTA) in human dental pulp cells (HDPCs). METHODS: Cell growth was determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay. Differentiation was evaluated by alkaline phosphatase (ALP) activity, alizarin red staining, and reverse-transcriptase polymerase chain reaction. RESULTS: The cell growth of HDPCs exposed to Emdogain and simvastatin plus BPC was superior to those administered BPC alone and similar to those that received MTA for 14 days. The simvastatin and Emdogain groups increased the odontogenic potential of the BPC group with respect to ALP activity, mineralization nodules, messenger RNA expression of ALP, osteopontin, osteocalcin, Runx2, and osterix. CONCLUSIONS: These results suggest that simvastatin and Emdogain improved cell growth and the differentiation of the BPC group in HDPCs and may be useful ingredients in BPC as pulp-capping material.

Effect of EDTA treatment on the hybrid layer durability in total-etch dentin adhesives.

The effect of the ethylenediaminetetraacetic acid (EDTA) treatment on the hybrid layer durability of total-etch dentin adhesives was investigated. A flat dentin surface was exposed and treated with 37% phosphoric acid or 0.1 M EDTA. Dentin adhesive was applied and a 4 mm thick composite resin was built-up. Twenty 0.9×0.9 mm(2) resin-dentin beams were fabricated in each experimental group. Artificial aging with 10% NaClO was performed in half of the experimental groups for 1 hour. A micro-tensile bond strength (µTBS) test was performed and the bonded interface was analyzed with transmission electron microscopy (TEM). The 37% phosphoric acid-treated group showed a lower µTBS after artificial aging, whereas the 0.1 M EDTA-treated group did not. TEM analysis revealed collagen fibrils dissolved in the 37% phosphoric acid-treated group but not in the 0.1M EDTA-treated group. Undissolved minerals were observed in the 0.1 M EDTA-treated group. In conclusion, a dentin treatment with 0.1M EDTA is effective in improving the hybrid layer durability.

A comparison of nickel-titanium rotary instruments manufactured using different methods and cross-sectional areas: ability to resist cyclic fatigue.

OBJECTIVE: This study examined the effect of the manufacturing methods (ground, electropolished, and twisted) and the cross-sectional area (CSA) of nickel-titanium (NiTi) rotary instruments on their cyclic fatigue resistance. STUDY DESIGN: A total of 80 NiTi rotary instruments (ISO 25/.06 taper) from 4 brands (K3, ProFile, RaCe, and TF) were rotated in a simulated root canal with pecking motion until fracture. The number of cycles to failure (NCF) was calculated. The CSA at 3 mm from the tip of new instruments of each brand was calculated. The correlation between the CSA and NCF was evaluated. All fractured surfaces were analyzed using a scanning electron microscope to determine the fracture mode. RESULTS: The TF instruments were the most resistant to fatigue failure. The resistance to cyclic failure increased with decreasing CSA. All fractured surfaces showed the coexistence of ductile and brittle properties. CONCLUSION: The CSA had a significant effect on the fatigue resistance of NiTi rotary instruments.