Taurodontism--a review.

UNLABELLED: Taurodontism is the morpho-anatomical change in the shape of a tooth, which involves enlargement of the body of the tooth and shortening of the roots. It has been reported in permanent and deciduous teeth, in premolars and molars and associated with certain syndromes, particularly in those involving an ectodermal defect. It has clinical implications which are relevant to both the general dental practitioner and the orthodontist. CLINICAL RELEVANCE: This review compiles the available literature concerning taurodont teeth and highlights the management issues raised by the anomaly.

An ex vivo laboratory study to determine the static frictional resistance of a variable ligation orthodontic bracket system.

OBJECTIVE: To determine the effects of static frictional resistance on varying the ligation technique in a Delta Force bracket system (Ortho Organizers Ltd, Hampton, UK) and using increasing degrees of bracket/archwire angulation to simulate binding. DESIGN: An ex vivo laboratory investigation using the Instron Universal Testing Machine (Instron Ltd, High Wycombe, UK) to generate sliding forces on an archwire through the Delta Force bracket. The system was lubricated with Saliva Orthana artificial saliva (Nycomed Ltd, Buckinghamshire, UK). SETTING: Biomaterials Laboratory, Eastman Dental Institute, London, UK. MATERIALS AND METHOD: Ninety Delta Force brackets were tested against 0.018-inch stainless steel wire. Three modes of ligation were tested with three different angulations: 0, 5 and 10 degrees to simulate increasing levels of binding. RESULTS: The average static frictional resistance went from 0.20 N, at 0 degrees angulation and minimum ligation, to 2.37 N with 10 degrees angulation and maximum ligation. Results revealed that the ligation pattern was found to be highly statistically significant (P<0.001) in influencing frictional force. The binding angle showed a trend of increasing frictional force with increasing bracket/archwire angulation. Repeatability testing showed no evidence of bias (P=0.171). CONCLUSIONS: These results suggest that the Delta Force variable ligation system does in fact enable friction to be varied, which may have implications in clinical application.