The evaluation of the effects of maxillary expansion and protraction therapy to the dentofacial structures and TMJ on sceletal class III patients

ABSTRACTKöse, C., The Evaluation Of The Effects Of Maxilary Expansion AndProtraction Therapy On Dentofacial Structures And TemporomandibularJoint In Skeletal Class III Patients. Baskent University Health SciencesInstitute Phd Thesis in Orthodontics, Ankara, 2007. The association betweenorthodontic treatment and temporomandibular joint dysfunction (TMD) has beendiscussed widely in the literature. It was reported that 75% of the force applied byfacemask was delivered to TMJ. The aim of this study was to examine the effectsof maxillary expansion and facemask therapy on dentofacial structures andcondyle-disc-glenoid fossa triple according to each other comparatively to thecontrol group. Patients included in the treatment (N=14) and control groups (N=12)all had skeletal and dental class III discrepancies. Patients were in the prepubertalstage of growth and they presented no signs and symptoms of TMD.The material of this study consists of lateral cephalometric films, hand-wrist films,magnetic resonance images and dental casts obtained before and after thetreatment and control periods. Cephalometric analysis included skeletal,dentoalveolar and soft tissue measurements and the condyle-disc position andshape, fossa morphology was evaluated from the MRI?s. Changes in the molarand canine widths were measured directly from the casts.According to the results, it was observed that, in the treatment group maxillarygrowth was stimulated and mandibular growth was controlled with posteriorrotation. Retraction of lower incisors and increase in the overjet had positiveeffects on the solution of the skeletal discrepancy. The soft tissue profileimproved, reflecting the skeletal and dentoalveolar changes. The evaluation ofdisc-condyle relationship revealed that the disc was slightly displaced anteriorly inthe treatment group, but this was not statistically significant when compared withthe control group. There were no changes in the position of the condyle accordingto the glenoid fossa. It was observed that the condylar angle slightly decreased inthe treatment group, while the difference between the groups was not significant.The fossa morphology did not change significant in either groups. There were anincrease in the position of discs in the compartment B, but this was also notsignificant when compared with the controls. 92.85% of the discs were bi-concaveat the end of treatment which is considered to be a normal disc shape. WhileRME/ face mask therapy had positive effects on the craniofacial structures, it wasnot found to be a predisposing factor for TMD.Keywords: TMJ, MRI, maxillary expansion/face mask, skeletal Class IIImalocclusion.