The labiopalatal impacted canine: Accurate diagnosis based on the position and size of adjacent teeth: A cone-beam computed tomography study.

INTRODUCTION: Labiopalatal impacted canines (L-PICs) occur when the canines lie between central and lateral incisors, with their tip palatal to the central incisor and part of their crown labial to the lateral incisor. Because of their unusual position, they are often misdiagnosed, and their orthodontic resolution fails. This study aims to provide clinicians with pathognomonic features for early and accurate positional diagnosis of L-PICs. METHODS: The L-PIC sample included 21 subjects with full diagnostic records. The control group of normally erupted canines was taken from a previous study. Clinical photographs, 2-dimensional radiographs, and cone-beam computed tomography were used to evaluate the positions of the adjacent incisors and first premolars, the canine incisor index, and the mesiodistal width of the lateral vs central incisors. RESULTS: Central incisors adjacent to L-PICs showed significant mesial root angulation, labial root inclination, and mesiolabial crown rotation, whereas lateral incisors presented significant distal root angulation, palatal root inclination, and mesiolabial crown rotation, in comparison to controls. The roots of the central and lateral incisors were divergent, in contrast to the controls, in which they were slightly convergent. The first premolar positions were not affected. The mean canine incisor index was significantly bigger in L-PICs vs the controls, suggesting a palatal canine. The lateral incisor widths were similar between the groups. CONCLUSIONS: This study provides the orthodontist with evidence-based clinical and radiographic red flags for diagnosing L-PIC, which may allow timely initiation of orthodontic treatment and correct planning of mechanotherapy.

Influence of common fixed retainers on the diagnostic quality of cranial magnetic resonance images.

INTRODUCTION: Orthodontists are often asked to remove fixed retainers before magnetic resonance imaging (MRI). This study was undertaken to assess the effects of 2 commonly used fixed retainers on MRI distortion and whether they should be removed. METHODS: MRI scans were performed on a dry skull with Twistflex (Dentaurum, Ispringen, Germany) and Ortho Flex Tech (Reliance Orthodontic Products, Itasca, Ill) retainers. Two neuroradiologists independently ranked the distortions. The influence of the fixed retainers' alloys, their distance to the area of diagnosis, location, strength of the magnetic field, and the spin-echo sequence were examined. Statistical analysis included kappa and Pearson chi-square tests. RESULTS: Ortho Flex Tech retainers caused no distortion. Twistflex retainers caused distortion in 46% of the tests in areas close to the retainer (tongue and jaws). Maxillary fixed retainers and the combination of maxillary and mandibular fixed retainers further increased the distortion. Greater distortion was observed with 3-T magnetic fields and T1-weighted spin-echo sequences. CONCLUSIONS: Removal of the Ortho Flex Tech retainer is unnecessary before MRI. Removal of the Twistflex should be considered if the MRI scans are performed to diagnose areas close to the fixed retainers, when 3-T magnetic fields and T1-weighted sequences are used, and when both maxillary and mandibular fixed retainers are present.

Periodontal status of impacted maxillary incisors uncovered by 2 different surgical techniques.

PURPOSE: The aim of this retrospective study was to compare the postretention clinical appearance and the pulpal and periodontal status of surgically exposed and orthodontically aligned impacted maxillary central incisors, treated by 2 different surgical techniques-open eruption (OE) versus closed eruption (CE). PATIENTS AND METHODS: The OE group consisted of 11 patients, age 15 to 38 years. The 11 patients in the CE sample (aged 14-28 years) were selected from a larger group of patients treated by this method, by carefully matching them to the patients in the OE group, in terms of cause and height of impaction. The length of the follow-up period was comparable for both groups (median of 9 years for the CE group and 10 years for the OE group). The clinical and radiographic variables were compared by paired t and chi(2) tests. RESULTS: The only parameters where statistically significant differences between the 2 study groups were found were crown length and bone support; that is, the central incisors uncovered by the OE technique had longer clinical crowns (by a mean of 1.37 mm) and decreased bone support (7.5% less on the mesial side) compared with those treated with the CE technique. Pulp changes with crown discoloration were only seen in the trauma-related group, independent of surgical technique. CONCLUSIONS: The choice of surgical technique in the exposure of impacted central incisors has important implications in the success of the orthodontic treatment of impacted incisors, in the long term, in relation to periodontal support and to appearance.