A reflection on radiographic cephalometry: the evaluation of sagittal discrepancy

Facial improvement after mandibular midline distraction and surgically assisted rapid maxillary expansion

This case report describes the retreatment of a 49-year-old woman with severe crowding in the mandibular incisor region and tapered maxillary and mandibular arches. Treatment consisted of mandibular midline distraction and surgically assisted rapid maxillary expansion to increase arch length. The need for proper presurgical orthodontics is described, and the complications during treatment are discussed. The results of treatment, including the superimposition of 3-dimensional facial scans, are presented. The treatment approach we used is typically indicated for patients with previous extractions of all first premolars who develop significant crowding after treatment. Surgical planning in 3 dimensions and the use of a 3-dimensional designed surgical osteotomy guiding wafer should improve the predictability of this treatment approach.

Evaluation of the influence of patient positioning on the reliability of lateral cephalometry

Two-dimensional cephalometry is widely used for monitoring orthodontic treatments and for quantifying the outcome of maxillofacial surgery. Despite careful use of a cephalostat, successive radiographs might differ due to slight differences in patient posture. This study evaluates the reliability of lateral cephalometric measurements and estimates the impact of patient positioning on this reliability. We studied cephalograms of 104 patients; 31 of them had two radiographs because the first was deemed unsuitable for cephalometric analysis. Using AudaxCeph 3.0 (Audax, Ljubljana, Slovenia), two observers traced each cephalogram twice, one month apart. We evaluated intra- and interobserver agreement via Bland-Altman analysis, intraclass correlation coefficient (ICC), standard error of measurement, and smallest detectable difference (SDD). First, we studied the reliability of the hard tissue part of the Tweed-Merrifield analysis for 73 single cephalograms and for the better ones of patients with two exposures. Then, we studied 31 unsatisfactory cephalograms, and the ones recorded at improved patient posture. Although intraobserver bias was less than 0.5° or 0.3 mm, interobserver bias was significant for most measurements. Intraobserver reliability was high (ICC > 0.9), whereas interobserver reliability was good (ICC > 0.83) except for FMPA, FMIA and OP. Head rotations and inclinations had little impact on reliability (e.g., interobserver SDD decreased for 3 of 11 measurements). We conclude that averaging the positions of bilateral structures enables a reliable cephalometric analysis in spite of imprecise patient posture. Retaking cephalograms is ethically questionable in such cases.