The effects of increasing the reverse curve of Spee in a lower archwire examined using a dynamic photo-elastic gelatine model.
This paper describes the development and testing of a dynamic in vitro photo-elastic model for evaluating the effects of orthodontic mechanics on an entire arch of teeth. A model of a mandibular arch was made and the teeth were embedded in a gelatine material with a high level of mechanical creep which permitted tooth movement in response to orthodontic forces. The excellent photo-elastic properties of this material also facilitated the analysis of the stress distribution around the roots of the teeth. The model of a mandibular arch was used to investigate the tooth movements and stress distributions produced by increasing the reverse curve of Spee in a 0.018 x 0.025-inch stainless steel archwire. The results revealed that a 1-mm reverse curve of Spee increased the arch length by 1.6 mm, but increasing the reverse curve of Spee to 5 mm did not increase arch length further. Photo-elastic analysis showed an increased stress distribution around the roots of the incisors and molars as the reverse curve of Spee was increased in the archwire.
Orthodontic Division, School of Clinical Dentistry, Queen's University of Belfast, UK.
P M
PM
Clifford
J F
JF
Orr
D J
DJ
Burden
D001718:Birefringence; D002508:Cephalometry; D003724:Dental Arch / Q000033:anatomy & histology* / Q000502:physiology; D003799:Dental Stress Analysis / Q000379:methods*; D005780:Gelatin; D006801:Humans; D008310:Malocclusion / Q000628:therapy*; D008334:Mandible / Q000502:physiology; D008954:Models, Biological; D003765:Models, Dental; D009969:Orthodontic Wires; D014087:Tooth Movement Techniques
D005780:Gelatin