Effect of dental arch convexity and type of archwire on frictional forces
Received 26 November 2007; received in revised form 7 June 2008; accepted 7 June 2008.
Introduction
Friction measurements in orthodontics are often derived from models by using brackets placed on flat models with various straight wires. Dental arches are convex in some areas. The objectives of this study were to compare the frictional forces generated in conventional flat and convex dental arch setups, and to evaluate the effect of different archwires on friction in both dental arch models.
Methods
Two stainless steel models were designed and manufactured simulating flat and convex maxillary right buccal dental arches. Five stainless steel brackets from the maxillary incisor to the second premolar (slot size, 0.22 in, Victory, 3M Unitek, Monrovia, Calif) and a first molar tube were aligned and clamped on the metal model at equal distances of 6 mm. Four kinds of orthodontic wires were tested: (1) A. J. Wilcock Australian wire (0.016 in, G&H Wire, Hannover, Germany); and (2) 0.016 × 0.022 in, (3) 0.018 × 0.022 in, and (4) 0.019 × 0.025 in (3M Unitek GmbH, Seefeld, Germany). Gray elastomeric modules (Power O 110, Ormco, Glendora, Calif) were used for ligation. Friction tests were performed in the wet state with artificial saliva lubrication and by pulling 5 mm of the whole length of the archwire. Six measurements were made from each bracket-wire combination, and each test was performed with new combinations of materials for both arch setups (n = 48, 6 per group) in a universal testing machine (crosshead speed: 20 mm/min).
Results and Conclusions
Significant effects of arch model (P = 0.0000) and wire types (P = 0.0000) were found. The interaction term between the tested factors was not significant (P = 0.1581) (2-way ANOVA and Tukey test). Convex models resulted in significantly higher frictional forces (1015-1653 g) than flat models (680-1270 g) (P <0.05). In the flat model, significantly lower frictional forces were obtained with wire types 1 (679 g) and 3 (1010 g) than with types 2 (1146 g) and 4 (1270 g) (P <0.05). In the convex model, the lowest friction was obtained with wire types 1 (1015 g) and 3 (1142 g) (P >0.05). Type 1 wire tended to create the least overall friction in both flat and convex dental arch simulation models.
aPostgraduate student, Department of Orthodontics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
bProfessor and research associate, Department of Dentistry and Dental Hygiene, Clinical Dental Biomaterials, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
cProfessor, Department of Orthodontics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
Reprint requests to: Mutlu Özcan, University Medical Centre Groningen, University of Groningen, Department of Dentistry and Dental Hygiene, Clinical Dental Biomaterials, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.
ABSTRACT