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The aim of this longitudinal study was to compare the prevalence of malocclusion at ages 3 and 7 years in a sample of children, exploring the hypothesis that prevalence of malocclusion is higher at 3 than at 7 years of age and may be influenced by sucking habits. The study sample comprised 386 children (199 girls and 187 boys), aged 3 years at study start, sourced from three Public Dental Service clinics in Sweden. Malocclusion was diagnosed by clinical examination, using a specific protocol. Data on allergy, traumatic injuries, sucking habits, and breathing pattern including nocturnal breathing disturbances were obtained by means of a questionnaire answered by child and parent in conjunction with the initial and final clinical examination. The overall prevalence of malocclusion decreased significantly, from 70 to 58% (P< 0.0001): predominantly anterior open bite, excessive overjet, and Class III malocclusion. Although high rates of spontaneous correction were also noted for deep bite, Class II malocclusion and posterior and anterior crossbites, new cases developed at almost the same rate; thus, the prevalence was unchanged at the end of the observation period. Anterior open bite and posterior crossbite were the only conditions showing significant associations with sucking habits. The results confirm the hypothesis of higher prevalence of malocclusion at 3 years of age and clearly support the strategy of deferring orthodontic correction of malocclusion until the mixed dentition stage.

This sample revealed a significant percentage of malocclusions and orthodontic treatment need. A substantial number of self-corrections and establishment of new malocclusions occurred during the transition from primary to early permanent dentition.

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Compared to the controls, asymmetry was registered in both dental arches. The crossbite side, measured to the midline, was narrower than the non-crossbite side in the upper jaw but broader in the lower jaw. Differences between upper/lower widths (at intercanine and intermolar level) seem to be of importance for correction or non-correction, both for "untreated" and "treated" children. A narrow crossbite side in the upper arch together with a broad crossbite side in the lower arch was found in non-corrected children in both groups, even among those treated with maxillary expansion, where the SNB angle was larger and the ANB angle smaller than in controls as well as in those with correction (including self-correction). Possibilities and limitations of treatment planning are discussed.

Objective: To evaluate the effect of the extraction of deciduous canines on palatally displaced canines (PDCs), to analyze the impact of the age of the patient on this interceptive treatment, and to assess the outcome of one-sided extraction of a maxillary primary canine on the midline of the maxilla. Materials and Methods: This study included 48 PDCs in 24 consecutive patients with bilateral PDCs. The mean age of the patients at diagnosis was 11.6 years (standard deviation 1.2 years). After randomization, one deciduous canine of each patient was assigned to extraction, and the contralateral side served as control. The patients were then followed at 6-month intervals for 18 months with panoramic and intraoral occlusal radiographs. Results: The rates of successful eruption of the PDCs at extraction and control sites were 67% and 42%, respectively, at 18 months. The difference between the sites was statistically significant, and the effect was significantly more pronounced in the younger participants. A significant decrease in arch perimeter occurred at extraction sites compared to control sites during the observation period. No midline shift toward the extraction side was observed in any patient.

The purpose of this retrospective study was to assess the relationship between the initial position of palatally displaced canines (PDCs) on panoramic radiographs and the duration of the orthodontic treatment and further to estimate the costs of the treatment. Data from panoramic radiographs and patient records of 66 consecutive patients (mean age 14.9 ± 1.7 years) with PDC were analysed. The initial position of the canine, the distance between the canine cusp tip and the occlusal plane, and the inclination of the canine were significantly associated with treatment duration both unadjusted and adjusted for background characteristics. The average estimated cost of the treatment of PDC was €3200 per case. The total annual cost for treatment of PDC in Sweden may therefore be estimated at €600,0000. In this study, duration of treatment averaged 17 months for canines displaced in impaction zone 1 or 2, 2.6 [95% confidence interval (CI) -1.0 to 6.2] months longer for those in impaction zone 3, and 7.6 (95% CI 4.1-11.1) months longer for canines displaced in impaction zone 4 or 5. This information makes it easier, through study of the panoramic radiograph, to estimate the duration of treatment and to give patients more precise information about the expected length of their treatment.

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