Evaluation of the fit of preformed nickel titanium arch wires on normal occlusion dental arches

Aim: To determine the fits of preformed nickel titanium [NiTi] archwires on dental arches with normal occlusion

Methods: Forty sets of upper and lower plaster models were obtained from men and women with Class I occlusions. Preformed 0.016'' × 0.022'' NiTi archwires from Rocky Mountain Orthodontics [RMO], 3 M Unitek, Ormco, and Dentaurum were evaluated in terms of their fits on dental arches from male, female, and combined cases. Data were analyzed by using fourth- and sixth-order polynomial equations, analysis of variance [ANOVA], and the Duncan post hoc test

Results: In the upper arches, the best fit and least error were obtained with RMO Ovoid and Ormco Orthos Large archwires for male cases, but with 3 M Orthoform LA archwires for female and combined cases. In the lower arches, the best fit and least error were obtained with Ormco Orthos Large for male cases, with 3 M Orthoform LA and RMO Normal for female cases, and with 3 M Orthoform LA, RMO Normal, Ormco Orthos Large, and Ormco Orthos Small for combined cases. When both dental arches were matched, Ormco Orthos Large was the best wire for male cases. 3 M Orthoform LA was the best wire for female and combined cases

Conclusions: Using an archwire form with the best fit to the dental arch should produce minimal changes in the dental arch form when NiTi wires are used and require less customization when stainless-steel wires are used

applicability of a non-anatomical soft and hard tissue centroid line [S and H centroid] in cephalometrics

The applicability of a newly introduced non-anatomical soft and hard tissue cephalometric centroid line [S and H centroid] was investigated. The "S and H centroid" line established from 12" X 14" lateral cephalometric radiographs of 57 selected adults was used as a base to create a new cephalometric reference line "Centroid-Nasion". The reliability and the use of the newly created "Centroid-Nasion" as a reference line was tested against the conventional "Sella-Nasion" cephalometric reference line to evaluate the sagittal and vertical maxillary and mandibular relationship. Pearson's correlation coefficient, one way ANOVA, and Tukey multiple comparison post Hoc statistical tests were used. The digitization technique was reliable. The "Centroid-Nasion" cephalometric reference line created by utilizing the "S and H centroid" line, was found to be as useful as the conventional "Sella-Nasion" cephalometric plane in establishing and differentiating between sagittal and vertical intermaxillary relationships