ABSTRACT
OBJECTIVES: To compare mandibular incisor root volume change (RVC) after 6 months between an anterior bite plane fabricated from acrylic resin (ABP) and thermoplastic materials (TBP) in a group of growing patients. MATERIALS AND METHODS: Thirty-four deep bite patients (age: 11.57 ± 1.30 years) were randomized into the ABP or TBP group. The RVC from before treatment (T0) to 6 months after treatment (Tct) at the labio-coronal (La1), labio-middle (La2), labio-apical (La3), linguo-coronal (Li1), linguo-middle (Li2), and linguo-apical (Li3) segments were investigated from cone beam computed tomography (CBCT) images. Cephalometric changes between T0 and the visit that normal overbite was achieved (Tcep) were also assessed (α = 0.05). RESULTS: Thirty-four patients completed the trial. Treatment duration was 5.0 ± 2.9 months. Significant decrease in root volume (RV) was found at the La2, La3, and Li3 segments of the ABP group (P < .05). No significant RVC was found in any segment of the TBP group (P ≥ .05). Comparing between groups, the RVC at La3 and Li3 of the ABP group was significantly greater than that of the TBP group (P < .05). However, total RVC between groups was not significantly different (P ≥ .05). CONCLUSIONS: Growing patients undergoing deep bite correction for 6 months with ABP displayed more apical RVC of mandibular incisors than those who used TBP. However, total RVC between appliances was not significantly different.
Subject(s)
Incisor , Overbite , Humans , Child , Incisor/diagnostic imaging , Overbite/therapy , Prospective Studies , Acrylic Resins , Mandible/diagnostic imagingABSTRACT
BACKGROUND: Anterior bite planes are bite-raising appliances used for deep bite correction. However, muscle responses to anterior bite planes of different harnesses may vary. OBJECTIVES: To prospectively evaluate masticatory muscle activity, muscle balance and maximum bite force (MBF) responses to anterior bite planes fabricated from acrylic resin (ABP) or bi-laminate thermoplastic (TBP) over 6 months in children with a deep bite. METHODS: Sixty-six children were randomly assigned to the ABP, TBP or untreated control groups. Masticatory muscle activity, activity index (AC) and percentage overlapping coefficient (POC) were assessed by surface electromyography; MBF, using a custom-made bite force sensor. Data were collected before, immediately after appliance insertion and after 2 weeks and 1, 3 and 6 months of treatment. Within- and between-group differences were analysed using the one-way ANOVA/Kruskal-Wallis and Mann-Whitney U tests (α = .05); Friedman's tests were used to assess within-group differences over time (α = .08). RESULTS: At rest, no dependent variables changed throughout the study. At maximum clenching, masticatory muscle activity immediately dropped significantly but returned to baseline values and was equal to the control group at 1-3 months. The ABP group had significantly lower masseter activity and AC than the TBP group after insertion. Neither POC nor MBF were significantly different within or between groups. CONCLUSION: Masticatory muscle activity reduced after anterior bite plane insertion but returned to baseline after 1-3 months. Masseter activity decreased significantly more in the ABP group than TBP group. Neither appliance significantly affected POC or MBF. CLINICAL TRIAL REGISTRATION: Thai Clinical Trial Registry (TCTR20210330002).
