Dental Tribune United Kingdom Edition

The Academy A4 Advert FINAL.indd 1 21/09/2012 10:53 T he aim of orthodontic diagnosis is to identify dento-alveolar, skeletal and functional alterations in the maxillo-facial complex. Diagno- sis and treatment planning are based on a combination of study models, intra-oral and extra-oral images, and radiographs, tradi- tionally consisting of panoramic and cephalometric radiographs. Cephalometric analysis (CA) plays an important role in diagno- sis and treatment planning. Traditional CA is based on three different X-ray projections: latero-lateral teleradiography, postero-anterior teleradiography and axial projection. However, conventional radiographs are lim- ited because they provide a 2-D representation of 3-D structures. The traditional system, analysing the three dimensions separately, is insufficient because dento-fa- cial alterations often take place in 3-D space. Thus, the limits of traditional CA are: • Errors in radiographic projec- tion, resulting in enhancements and distortions • Operator errors in the measure- ment systems • Errors in the identification of the cephalometric landmarks owing to superimposition of anatomic structures -Inability to evaluate the three di- mensions of the craniofacial com- plex.1 The recent introduction of CBCT in combination with com- puter software allows the applica- tion of this new methodology to different fields of dentistry, includ- ing its successful use in orthodon- tics (Fig. 1).2 Owing to CBCT, the 3-D morphology of the cranial skeletal structures can be repre- sented properly. With CBCT, the patient is exposed to similar lev- els of radiation as during conven- tional CA and up to 20 times less than during multi-slice-CT exams (Table I).3 At the Orthodontic Depart- ment at the University of Milan, CA is performed with a new 3-D methodology that allows for an easy, effective and repeatable way to decrease operator-driven er- rors.4 It is based on the identifica- tion of 18 points (10 median and 8 lateral), all of which are identi- fied on a hard tissue CT section and verified on the two remaining CT sections. Further verification is then performed on the volume rendering generated by SimPlant OMS (Materialise). The 18 points determine 36 measurements on the sagittal, vertical and transver- sal dimensions (Fig 2). At the Uni- CBCT in Orthodontics Prof Giampietro Farronato, Dr Francesca Bellincioni, Dr Margherita Colombo, Dr Daniela Falzone, Dr Salvadori Sara, Dr Gaia Passaler & Dr Gianfranco Santamaria page 22DTà ‘The recent intro- duction of CBCT in combination with computer software allows the appli- cation of this new methodology to different fields of dentistry, including its successful use in orthodontics’ 21ClinicalOctober 29 - November 4, 2012United Kingdom Edition