Retno Widayati

Comparison of tumor necrosis Factor-α concentrations in gingival crevicular fluid between self-ligating and preadjusted edgewise appliances in the early leveling stage of orthodontic treatment

Introduction: Tumor necrosis factor-α (TNF-α) is an important proinflammatory cytokine that regulates the early phase of inflammation reaction during orthodontic tooth movement. The aim of the present study was to compare TNF-α concentrations in the gingival crevicular fluid (GCF) between preadjusted edgewise appliance (PEA) and self-ligating (SL) systems during the early leveling stage of orthodontic treatment. Materials and Methods: Eighteen patients (aged 15–35 years) who participated in this study were divided into two experimental groups (PEA and SL) and control group (without orthodontic treatment). The GCF was taken at five sites in the maxilla anterior teeth from each participant just before bracket bonding and at 1, 24, and 168 h after the initiation of tooth movement. Cytokine levels were determined through ELISA. Results: The concentration of TNF-α was significantly higher in the experimental groups than in the control group at 24 h after force application. TNF-α levels were significantly decreased at 168 h after force application in the PEA group. Meanwhile, in the SL group, the level of TNF-α at 168 h was still increased, although there was no statistically significant difference. Conclusion: TNF-α concentration was increased at 1 h and 24 h after orthodontic force application in both the PEA and SL groups. In the PEA group, TNF-α concentration was significantly decreased at 168 h, meanwhile in the SL group, this value remained increased at this time point. The differences in TNF-α concentration between the PEA and SL groups may be caused by their different types of brackets, wires, and ligation methods.

Initial estimation of landmark location for automated cephalometric analysis using template matching method

An initial estimator algorithm, aims to localize the position of anatomical landmarks in lateral cephalogram, is presented. This proposed algorithm explores the use of affine transform and template matching to detect three essential reference points: two cephalostat projections (ear rods and nasal-positioner) and menton. The detection of cephalostat projections using template matching method are conducted in the first step. The second step, in which the initial menton positions and small expectation windows for menton are computed, is implemented using affine transform. The exact position of menton is then located within the expectation window using template matching method with sum of squared differences-based similarity measurement in the final step. Using a ten-fold cross validation scheme, we test the algorithm on 106 direct-digital lateral cephalograms. The experimental results show that the initial estimator can efficiently limit the search areas. The obtained detection rate within 4 mm accuracy window is 92.5 percent.