[The dry skull model in orthodontics].
Orthodontic therapy aims to displace teeth by means of orthodontic appliances. Forces, applied on the teeth, induce remodeling of the alveolar process in upper and lower jaw resulting in a new position of the teeth into both jaws. In this publication an attempt has been made to test a model (dry skull model) which could provide a better understanding of the effect of force application on tooth and bone displacement. Initial tooth displacement (microscopical), right after force application, could give an indication for the longitudinal tooth displacement to be expected. Variables as the point of force application, the amount and direction of the force and the localisation of the centre of resistance are determining factors for the final tooth displacement. This study attempts to forecast the longitudinal tooth displacement by evaluating the initial displacement on the dry skull. Initial tooth displacement has been measured by means of laser measuring techniques (holography, speckle interferometry and laser reflection technique). These techniques are non-invasive (non-destructive testing) and permit the measurement of small tooth and bone displacements varying between 0.5 and 15 microns. According to the results of the animal studies, it became obvious that initial tooth and bone displacements are indicative for the longitudinal effect of the same sort of force application on a short time basis (5 to 8 weeks). The final conclusion is that initial tooth displacement measured on a dry skull has a predictive value for the longitudinal effect of orthodontic force application. Moreover, the creation of a finite element model looks very promising in this respect. More research is needed to test the finite element model further and to make it useful for testing the effect of force application on skull and tooth structures of a patient.
Dermaut
L R
LR
RUG, Vakgroep Tandheelkunde Afdeling Orthodontie, UZ De Pintelaan 185, B 9000 Gent.
D000818:Animals; D006801:Humans; D008954:Models, Biological; D009967:Orthodontic Appliances; D009970:Orthodontics / Q000379:methods*; D011312:Pressure; D014085:Tooth Migration