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BACKGROUND: Lingual bracket system is the best invisible orthodontic appliance due to its aesthetics and efficiency, but it is difficult to control anterior tooth torque during the distal retraction of the anterior tooth. Thereafter, lots of studies on maxillary anterior teeth have been conducted, but there is less knowledge about the mechanical characteristics of whole mandible dentition distal retaction. OBJECTIVE: To analyze the biomechanical characteristics of the mandibular anterior teeth distal retracted by sliding method in lingual orthodontic treatment. METHODS: A three-dimensional finite element model was constructed using a series of specialized software based on volunteer's CT data and lingual brackets, including the mandible, alveolar bone, periodontal ligament, dentition (removal of the two first premolars), lingual brackets and arch wire with hooks (located between lateral incisor and canine and 11 mm distant from the arch wire plane). Subsequently, 1.5 N lingual forces through the hooks of first molar (2 mm distant from the arch wire plane) and the hooks between the lower lateral incisor and canine were loaded and the biomechanical characteristics of the mandibular anterior teeth movement during the en-masse retraction were analyzed. RESULTS AND CONCLUSION: The finite element model was constructed successfully, and had a higher geometrical similarity and resemblance of clinical situation. The crowns of lower incisors showed the tendency of lingual inclination and extension, and this tendency was more obvious in the lateral incisors. The canines were buccal and mesial inclination and intrusion. The periodontal stress concentration area was corresponded with the tendency of tooth movement. Therefore, the movement tendency of incisors is still lingual inclination when mandibular anterior teeth distal retracted by a longer hook in lingual brackets system, and there is no distal inclination. Overall, lower incisors are easy to exhibit lingual inclination; the long anterior hooks contribute to the movement of canines, but it is not available for the vertical control of incisors during mandibular anterior tooth distal retraction.
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BACKGROUND: Mandibular advancement devices are commonly used in patients with mild to moderate obstructive sleep apnea hypopnea syndrome. But wearing with mandibular protraction appliance makes the mandible in an abnormal position, and inevitably affects the temporomandibular joint (TMJ). As one of the important components of the TMJ, can structural changes of the joint disk impair the TMJ? Are there any differences in the TMJ structure between Angle Class Ⅰ and Class Ⅱ? What will happen to the TMJ structure in the Angle Class Ⅰ and Class Ⅱ during mandibular advancement? Is there a same law of TMJ changes for Angle Class Ⅰ and Class Ⅱ? All of these are undetermined systematically. OBJECTIVE: To compare the changes in the structure of TMJ disk and the differences during mandible advancement between Angle Class Ⅰ and Class Ⅱ adult males. METHODS: Forty non-apnea adult males were divided into two groups (n=20 per group), including Class Ⅰ and Class Ⅱ groups, according to the Angle's classification and sagittal skeletal facial type. Each volunteer was scanned by MRI in three positions, including central occlusion (F0), 75% of the maximum mandible advancement (F75) and maximum of the mandible advancement (F100). These indexes that were correlated with morphology of the joint disk in different mandible advancement positions were measured and calculated by MRI, and then analyzed statistically. RESULTS AND CONCLUSION: In F0, the ratio of disk anterior displacement in the Class Ⅱ group was higher than that in the Class Ⅰ group (P< 0.01). The angle A was decreased as the mandible advanced in both groups from F0to F75(P < 0.01). The rotational angular dimension was increased as the mandible advanced, and the sizes from F0to F100were bigger than those from F0to F75(P < 0.05). Some differences existed in the structure of TMJ disk between Angle Class Ⅰ and Ⅱ adult males. In summary, appropriate mandibular advancement may play a positive role in patients with anterior displacement of the joint disk, but excessive mandible advancement is likely to impair the TMJ disk.
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Purpose To summarize the clinicopathologic features,diagnosis and differential diagnosis of nodular fasciitis (NF) of the breast.Methods Clinicopathologic findings of four mammary NF cases were retrospectively reviewed.Immunohistochemical of EnVision staining was performed in all cases.Results The median age of all patients was 50.5 years.All patients were female,without history of trauma.The average size was 1.2 cm.Among the four cases reviewed,three lesions occurred in the mammary parenchyma and one next to the skin.Histologically,the lesion was composed of plump spindle cells arranged in short fascicles with erythrocytes extravasation and patchy lymphoid infiltration,and the border of three cases was infiltrative.Immunohistochemically,the spindle cells were positive for vimentin,CD10 and SMA,but negative for CK (AE1/AE3),CK5/6,CK14,CAM5.2,ER and PR.All patients underwent surgical resection,with no evidence of recurrence.Conclusion NF of the breast is rare.It should be differentiated from some benign and malignant tumours,such as fibromatosis,phyllodes tumor and low-grade fibromatosis-like metaplastic carcinoma.The immunostaining of vimentin and SMA may helpful for the diagnosis and differential diagnosis of NF of breast.
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<p><b>OBJECTIVE</b>To evaluate the effects and mechanisms of the microscrew implant anchorage (MIA) combined with multi-loop edgewise arch wire (MEAW) technique in the treatment of skeletal Class II adult patients.</p><p><b>METHODS</b>Eleven adult patients with skeletal Class II high-angle malocclusions were treated with fixed appliances. The spaces were closed by the springs from the MIA to the hook on the archwire. The height of the hook and the direction of the force were different according to the intrusion and retraction of upper anterior teeth. In the finishing stage, MEAW technique and modified class II elastics (from the first loop of MEAW to the MIA) were used for final detailing. Cephalometric analysis was used to evaluate the effect after treatment.</p><p><b>RESULTS</b>After treatment, the decrease of SNA, ANB and FMA were (2.86 +/- 1.05) degrees , (2.82 +/- 0.96) degrees and (2.95 +/- 1.35) degrees , respectively. The torque control of upper anterior teeth was good. The protrusion of lower incisors and the molar extrusion were avoided. The upper molars were moved distally by (3.00 +/- 2.19) mm.</p><p><b>CONCLUSIONS</b>The treatment of adult patients with skeletal Class II high angle malocclusions with MIA and MEAW technique could not only improve the facial esthetics but also avoided the common side effects of traditional Class II elastics.</p>