ABSTRACT
INTRODUCTION: Deepbites can be corrected by intrusion of mandibular anterior teeth. Direct anchorage with miniscrews simplifies complex tooth movements; however, few studies have reported their use for mandibular anterior intrusion. The purpose of this study was to evaluate, by means of the finite element method, initial tooth displacement and periodontal stress distribution using various mandibular anterior intrusion mechanics. Miniscrews were used as skeletal anchorage devices. METHODS: Cone-beam computed tomography scans were used for 3-dimensional reconstruction of the mandible and the mandibular anterior dentition. Models included the 4 incisors with or without the canines. After all surrounding periodontal and bony structures were determined brackets, segmental archwires, and miniscrews were added. Finite element studies were performed to assess initial tooth displacement and periodontal stress distribution with multiple intrusion force vectors. Changes in the location of the miniscrews and loading points on the archwire created 14 scenarios. RESULTS: Minimum buccolingual displacements, a uniform distribution of periodontal stress, and overall group intrusion for both 4-tooth and 6-tooth scenarios were best achieved when applying distointrusive vectors. The highest peaks of periodontal stress were observed when the force was directed at the corners of the segmental archwire. It was found that, in addition to distointrusive vectors, 4 loading points on the archwire were necessary for pure intrusion and uniform distribution of periodontal stress in the 6-tooth scenarios. CONCLUSIONS: The simulations in this study suggest that group intrusion of all 6 mandibular anterior teeth might be achieved by applying distointrusive vectors. Inserting a pair of miniscrews distal to the canine roots, 1 screw per side, and directing 4 loading points on the archwire generates uniform periodontal stress distribution and minimum buccolingual displacements. Local conditions, such as narrow bone width and attached gingiva level, play significant roles in the clinical viability of the proposed virtual scenarios.
Subject(s)
Dental Implants , Finite Element Analysis , Imaging, Three-Dimensional/methods , Incisor/surgery , Mandible/surgery , Orthodontic Anchorage Procedures/instrumentation , Tooth Movement Techniques/instrumentation , Tooth Movement Techniques/methods , Adult , Alveolar Process , Biomechanical Phenomena , Computer Simulation , Cone-Beam Computed Tomography/methods , Elastic Modulus , Female , Humans , Image Processing, Computer-Assisted/methods , Incisor/pathology , Malocclusion, Angle Class I/therapy , Mandible/pathology , Mechanical Phenomena , Models, Biological , Orthodontic Appliance Design , Orthodontic Brackets , Orthodontic Space Closure/methods , Orthodontic Wires , Stress, MechanicalABSTRACT
OBJECTIVES: To determine the effectiveness of a motivational interviewing-based educational program in reducing the number and intensity of new caries and bacterial dental plaque levels at 6 months post randomization. STUDY DESIGN: A randomized and single blind clinical trial in 100 schoolchildren between 6-10 years of age presenting the highest risk score of caries according to the Caries Management by Risk Assessment (CAMBRA) criteria was performed. These patients were randomized to two groups: control (in which the mothers initially received an oral prevention informative session) and experimental (in which the mothers received the initial informative session, followed by individual motivational interviewing sessions during a period of 6 months). The International Caries Detection and Assessment System (ICDAS) scores and bacterial plaque were evaluated at baseline, at 6 and 12 months. RESULTS: After 12 months, children in the experimental group had 2.12 ± 0.8 new caries versus 3.5 ± 0.9 in the control group (t=7.39; p<0.001). Caries in the experimental group was seen to be limited to the enamel, with a median intensity of 2 (range 0-3) versus 3 (0-6) in the control group (U=1594; p<0.0001). Bacterial plaque determined by the O'Leary index decreased in both groups; however, it decreased more in the experimental than in the control group (34.3 vs. 20.6; t=-3.12, p= 0.002) respectively. CONCLUSIONS: Motivational interviewing is better than traditional educational programs in preventing caries and decreasing bacterial plaque. Key words:Health educational, motivational interviewing, caries risk.
