Paravichaya Kokiatsirikul. Pretreatment and posttreatment change of clinical dental arch form in angle's classification II division 1 in Thai . Master's Degree(Orthodontics). Mahidol University. : Mahidol University, 2008.
Pretreatment and posttreatment change of clinical dental arch form in angle's classification II division 1 in Thai
Abstract:
The purpose of the present study was to define a generalized equation describing
a Thai person’s dental arch form as specified in Angle’s classification II, Division 1.
This was done by applying a computer-curve fitting program to compare the
pretreatment and posttreatment clinical dental arch form, and to determine arch wire
selection for treatment in Angle’s classification II, Division1 malocclusion in Thais.
The study was comprised of 22 sets (8 males and 14 females) of pretreatment and
posttreatment dental models which initially expressed Angle’s Classification II,
Division 1 malocclusion. The following describes the pretreatment and posttreatment
clinical dental arch form : Fourteen and twelve dental landmarks on the bracket
positions from the buccal surface of molars, premolars, the labial surface of the
canines and incisors of each dental models were triggered and recorded using the
Coordinate Measuring Machine and reported into their corresponding coordinates (X-,
and Y- direction). These coordinates were processed through a computer curve-fitting
program to define the parameter of beta function in order to describe their dental
arches.
The dental arch forms of Thai people who had a Class II, Division 1
malocclusion were shown to be accurately represented mathematically by the beta
function. The coefficient of the determination between the measured arch-shape data
and the mathematical arch shape was expressed by the beta function. The average
coefficient was 0.97 with a standard deviation of 0.02. When pretreatment and
posttreatment Class II were compared, there was a statistically significant decrease in
a-parameter (arch depth) and intermolar width both in maxillary and mandibular
arches, but the remaining parameters were not statistically significant different. When
sexual dimorphism was examined, males showed a larger arch form than the females
but only in pretreatment maxillary arch depth (a-parameter) maxillary and mandibular
intermolar width. The results revealed that gender seemed to have little influence on
arch form differences. For the arch wires selection, Class I and Class II, Division 1
dental arch form fitted quite nicely with the OrthoForm tapered-shaped preformed
arch wire.