The ectopic mandibular canines can start tooth formation in three different locations: a case series study based on single orthopantomograms from 47 individuals.

INTRODUCTION: A former study on orthopantomograms from young children with abnormal dental development (not canine ectopia) demonstrated that the tooth bud of the mandibular canine, compared to a stable longitudinal canine axis, could be located normally, anteriorly or posteriorly, with close relation to the first premolar. AIM: The aim of the present study is to analyse on orthopantomograms if the canine axis can demonstrate where the ectopic mandibular canine started tooth formation. MATERIALS: The material consists of orthopantomograms with ectopic mandibular canines and presence of primary mandibular canines from 47 cases (29 cases 9-21 years old and 18 cases with unknown ages). The primary canines demonstrated from minor apical resorption to more severe apical resorption. METHODS: Based on canine maturity, location of the canine axes and the interrelationships between the roots of the permanent canine and first premolar, the location from where the canine started tooth formation was determined. Canine maturity. Maturity stage below half root length and maturity stage above half root length revealed that 11 ectopic canines had less than half root length and 36 cases more than half root length. Canine axes. The canine axis, through the length of the primary canines Ax, is inserted on drawings of the orthopantomograms using the tracing programme Inkscape®. Interrelationship between roots. By visual inspection, the distance between the canine and first premolar was designated close distance, normal distance and extended distance. RESULTS: The results are divided into 3 groups. Group 1: The initial site of the permanent ectopic canine is located within the canine axis (6 cases). Group 2: The initial site of the permanent ectopic canine is located posterior to the canine axis (36 cases). Group 3: The initial site of the permanent ectopic canine is located anterior to the canine axis (5 cases). CONCLUSION: The study explained that the canine axis could divide cases of ectopic canines into three groups according to the location from where tooth formation starts. For getting closer to the pattern of the ectopic canine eruption, it is necessary to analyse series of orthopantomograms taken from the same individual over several years.

The location of the permanent mandibular canine as identified in orthopantomograms from children younger than 5 years of age: a case series study.

AIM: The aim of this case series study is to describe where the crowns of the permanent mandibular canines are located in early childhood in relation to the preceding primary canines. MATERIALS AND METHODS: From a sample of 31 orthopantomograms from children, younger than 5 years of age, the location of the mandibular canines was analysed by visual inspection. The radiographs were taken due to different deviations in the dentition and forwarded during a period of 28 years for elucidating different diagnostic questions. From an embryological point of view, the primary canine was considered as a stable structure in the jawbone. A longitudinal axis through the primary canine was named the canine axis. The initial site of the permanent crown was the site, where the permanent lamina "placed" the tooth bud for final development. A normal site was determined when the canine axis passed though the permanent crown and a pathological site was determined when this did not happen. RESULTS: Normal sites for the permanent crowns were observed in 19 cases and abnormal sites in 8 cases. In four cases, the interrelationship between the canine axis and the permanent crown could not be decided. The study demonstrated that the tooth germ for the permanent canine can start initial formation misplaced distally or mesially to the preceding primary tooth. CONCLUSION: The study demonstrates different malpositions of the initial crowns of the permanent mandibular canines in children younger than 5 years of age. The results are considered of importance for future understanding of the aetiology behind ectopic mandibular canines.

Long-term side effects on the temporomandibular joints and oro-facial function in patients with obstructive sleep apnoea treated with a mandibular advancement device.

Patients with obstructive sleep apnoea (OSA) in long-term treatment with a mandibular advancement device (MAD) to increase the upper airway space may develop changes in the temporomandibular joint (TMJ) and the oro-facial function due to the protruded jaw position during sleep. The aim was to investigate the influence of long-term MAD treatment on the TMJs, oro-facial function and occlusion. This prospective study included 30 men and 13 women (median age 54) with OSA [Apnoea-Hypopnoea Index (AHI): 7-57]. They were examined with the Nordic Orofacial Test Screening (NOT-S), the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and cone beam computed tomography (CBCT) of the TMJs. The examination was performed before MAD treatment (T0), and 3-6 months (T1, no CBCT), 1 year (T2) and 3 years (T3) after treatment start. The results were analysed as long term (T0-T3, n = 14) and short term (T0-T2, n = 24) by t-test, Fisher's exact test and anova. Both long- and short-term analyses revealed a reduction in AHI (P < 0·002). Significant long term were increased scores in the NOT-S Interview (P < 0·045), reduced vertical overbite (P < 0·031) and increased jaw protrusive movement (P < 0·027). TMJ changes were found as joint sounds in terms of reciprocal clicking and crepitus, short term as a decrease and subsequent recurrence (P < 0·053; P < 0·037). No significant radiological changes were found. In conclusion, MAD treatment is beneficial to some OSA patients, but might induce changes in the TMJs, the oro-facial function and the occlusion. However, these changes seemed to be less harmful than previously reported with careful adaptation, control and follow-ups.

Cervical vertebral column morphology in patients with obstructive sleep apnoea assessed using lateral cephalograms and cone beam CT. A comparative study.

OBJECTIVES: Few studies have described morphological deviations in obstructive sleep apnoea (OSA) patients on two-dimensional (2D) lateral cephalograms, and the reliability of 2D radiographs has been discussed. The objective is to describe the morphology of the cervical vertebral column on cone beam CT (CBCT) in adult patients with OSA and to compare 2D lateral cephalograms with three-dimensional (3D) CBCT images. METHODS: For all 57 OSA patients, the cervical vertebral column morphology was evaluated on lateral cephalograms and CBCT images and compared according to fusion anomalies and posterior arch deficiency. RESULTS: The CBCT assessment showed that 21.1% had fusion anomalies of the cervical column, i.e. fusion between two cervical vertebrae (10.5%), block fusions (8.8%) or occipitalization (1.8%). Posterior arch deficiency occurred in 14% as partial cleft of C1 and in 3.5% in combination with block fusions. The agreement between the occurrence of morphological deviations in the cervical vertebral column between lateral cephalograms and CBCT images showed good agreement (κ = 0.64). CONCLUSIONS: Prevalence and pattern in the cervical column morphology have now been confirmed on CBCT. The occurrence of morphological deviations in the cervical vertebral column showed good agreement between lateral cephalograms and CBCT images. This indicates that 2D lateral cephalograms (already available after indication in connection with, e.g. treatment planning) are sufficient for identifying morphological deviations in the cervical vertebral column. For a more accurate diagnosis and location of the deviations, CBCT is required. New 3D methods will suggest a need for new detailed characterization and division of deviations in cervical vertebral column morphology.