6 research outputs found

    Orthodontische behandeling en wortelresorptie

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    Root resorption caused by different orthodontic force regimes

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    Comparison of facial morphology in two populations with complete unilateral cleft lip and palate from two different centers.

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    Contains fulltext : 50528.pdf (publisher's version ) (Closed access)OBJECTIVE: To identify differences in craniofacial morphology of two populations with a history of complete unilateral cleft lip and palate (UCLP) treated under different protocols. DESIGN: Retrospective longitudinal cohort study. SETTING: Cleft Center of the University of Nijmegen, The Netherlands, and the Cleft Lip and Palate Program, The Hospital for Sick Children, Toronto, Canada. SUBJECTS: Nineteen patients (16 male, 3 female) from Nijmegen and 19 patients (16 male, 3 female) from Toronto. Each patient was matched for sex and age with a patient from the other group. The mean ages at which lateral cephalometric radiographs were available for the Nijmegen group were 5.5, 9.9, and 18.3 years, while for the Toronto group these were available at mean ages of 5.3, 10.1, and 18.3 years, respectively. Eighteen patients from the Nijmegen group received an alveolar bone graft at a mean age of 9.5 years (range 8.2 to 13.5 years). None of the patients from Toronto received bone grafts. MAIN OUTCOME MEASURES: Eighteen cephalometric variables per radiograph were calculated at each time registration, using Dentofacial Planner cephalometric software. Statistical evaluation was performed with repeated-measures analysis of variance. RESULTS: No differences were seen in the maxillary measurements. The patients in the Toronto group had significantly larger mandibles at all three time registrations. CONCLUSIONS: The Nijmegen and Toronto protocols resulted in similar maxillary projections in patients with UCLP. Comparison of data from other studies supports the contention that the larger profile convexity of the Nijmegen group is a reflection of a genetically determined smaller mandibular size in the Dutch population

    Incidence and severity of root resorption in orthodontically moved premolars in dogs.

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    Contains fulltext : 58131.pdf (publisher's version ) (Closed access)OBJECTIVES: To study treatment-related factors for external root resorption during orthodontic tooth movement. DESIGN: An experimental animal study. SETTING AND SAMPLE POPULATION: Department of Orthodontics and Oral Biology, University Medical Centre Nijmegen, The Netherlands. Twenty-four young adult beagle dogs. EXPERIMENTAL VARIABLE: Mandibular premolars were bodily moved with continuous or intermittent controlled orthodontic forces of 10, 25, 50, 100, or 200 cN according to standardized protocols. At different points in time histomorphometry was performed to determine the severity of root resorption. OUTCOME MEASURE: Prevalence of root resorptions, defined as microscopically visible resorption lacunae in the dentin. Severity of resorption was defined by the length, relative length, depth, and surface area of each resorption area. RESULTS: The incidence of root resorption increased with the duration of force application. After 14-17 weeks of force application root resorption was found at 94% of the root surfaces at pressure sides. The effect of force magnitude on the severity of root resorption was not statistically significant. The severity of root resorption was highly related to the force regimen. Continuous forces caused significantly more severe root resorption than intermittent forces. A strong correlation (0.60 < r < 0.68) was found between the amount of tooth movement and the severity of root resorption. CONCLUSIONS: Root resorption increases with the duration of force application. The more teeth are displaced, the more root resorption will occur. Intermittent forces cause less severe root resorption than continuous forces, and force magnitude is probably not decisive for root resorption
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