Condylar lateral movements in patients with mandibular deviation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To record condylar movements of patients with mandibular deviation and analyze their characteristics.</p><p><b>METHODS</b>Computer aided diagnosis axiography (CADIAX III) was used to record and analyze condylar lateral movements in 31 patients (9 males, 22 females and the age range 12 - 26, mean age 18 years old) with mandibular deviation. Paired-t test and rank sum test were used to compare condylar movements. Multinomial logistic analysis was used to clarify the relationship between condylar movement and mandibular deviation.</p><p><b>RESULTS</b>The condylar lateral movements in patients with mandibular deviation were asymmetric. The tracing of the shifted side was longer than the contralateral side (P < 0.01). The transverse inclination of the shifted side was smaller than the contralateral side (P < 0.01). With the increase of deviation, the movement length difference between the two sides increased and the length of contralateral side decreased (P < 0.01).</p><p><b>CONCLUSIONS</b>The patients with mandibular deviation not only have morphological asymmetry but asymmetric condylar movement length and inclination in lateral movements. There is specific relationship between condylar movement and mandibular deviation.</p>

The relationship of wire offset and lingual component force on first molar / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To measure the strength of lingual component force on first molar while retraction canine by 150 g tractive force with different sizes of arch wire and with different widths of molar offset on the wire.</p><p><b>METHODS</b>Wires with different sizes and different materials [0.40 mm and 0.45 mm stainless round wires, 0.40 mm and 0.45 mm Australia wires, 0.41 mm x 0.56 mm (0.016 x 0.022 inch) and 0.46 mm x 0.63 mm (0.017 x 0.025 inch) rectangular stainless wires] were ligated in ideal arch Typodont when the canine was retracted with 150 g force in the direction from the molar buccal hook to the central point of canine bracket's distal wing under different widths of molar offset (1 mm, 2mm, 3mm). the lingual force applied on the first molar was measured by a self-made dynamometer.</p><p><b>RESULTS</b>1. There is lingual component force applied to the first molar while retracting canine with 150 g tractive force. 2. the bigger the cross section area of the wire and the stronger the rigidity of the wire, the smaller the lingual component force turns. The ability of the wire in deducting the lingual component force is in direct ratio with the cross section area and the rigidity of the wire. 3. While the width of wire offset increases, the lingual force produced by the tractive force applied to the first molar decreases lineally.</p><p><b>CONCLUSION</b>There is lingual force produced on the anchorage molar when retracting canine. In clinic for avoiding the lingual movement of the first molar, increasing the size of wire or increasing the width of wire offset is suggested.</p>