Nifedipine regulated periodontal ligament remodeling: an experimental study in rats.

OBJECTIVE: The aim of this study was to investigate the effects of nifedipine on periodontal ligament remodeling during orthodontic tooth movement. MATERIAL AND METHODS: Sixty male Sprague-Dawley rats were randomly divided into an orthodontic group and groups that received either 10 mg/kg or 40 mg/kg nifedipine (NIF). Immunohistochemical staining and image analysis were used to investigate the expression of matrix metalloproteinase (MMP)-1, -10, -13 and collagen-I in PDL, and maxillary 1st molar displacement was measured. RESULTS: Expression of MMP-1, -10, and -13 was significantly decreased in both NIF groups, while collagen-I expression was markedly increased. NIF significantly inhibited tooth movement. CONCLUSIONS: NIF affects the expression of MMP-1, -10, -13 and collagen-I and tooth movement induced by orthodontic force in rats, thus indicating that calcium channels might be important in mediating PDL remodeling.

[Treating high angle bimaxillary protrusion with three kinds of extraction method: a clinical study].

OBJECTIVE: To compare the effect of three kinds of extraction model on high angle bimaxillary protrusion patients. METHODS: A total of 30 patients with Class I malocclusion and bimaxillary protrusion, aged 14-25 years old, were selected and divided into three groups. Four first premolars were extracted in the first group. The two maxillary first premolars and two mandibular first molars were extracted in the second group. The two maxillary first premolars and two mandibular first molars were extracted in the third group, and two additional micro-implants used as orthodontic anchorage in maxilla. Three groups were all treated with MBT appliance. Cephalometric analysis were carried out before and after treatment, and the results were analyzed with statistics. RESULTS: 1) About the hard tissues, compared with the first group, there were statistically significant differences of N-Me, SGo/NMe, ANS-Me, FH/MP, SN/MP, and ODI in the second and the third group after treatment (P<0.01). 2) About the soft tissues, the teeth and the alveolar bone, compared with the first group, there were statistically significant differences of Pg-Pos, Li-SnPos, Si-LiPos, LL-E, L1-NB, L1/NB, U1/L1, L7-MP in the second and the third group after treatment (P<0.01). 3) All patients received consummate orthodontic treatment and obtained fine occlusion. Facial profiles were improved significantly after orthodontic treatment. CONCLUSION: 1) After orthodontic treatment with mandibular first molars extraction, FH/MP, SN/MP, N-Me, ANS-Me, L1-NB and L1/NB decreased respectively, and soft tissue profiles were improved significantly. 2) Additional micro-implant used as orthodontic anchorage in maxilla significantly contributed to the maxillary incisor retraction and subsequent soft tissue change. 3) The first molars extraction and additional micro-implant used as orthodontic anchorage are efficient in improving the facial profiles for high angle bimaxillary protrusion patients.

[Clinical application of modified distal-jet appliance in distalization of maxillary molar].

OBJECTIVE: To investigate the clinical effects of the maxillary molar distalization with modified Distal-Jet appliance. METHODS: 15 patients (average age 12.3 year-old) with maxillary molars shifting mesially were selected as the subjects. Maxillary molars of all patients were distalized with modified Distal-Jet appliance. RESULTS: All patients achieved good occlusion, normal overjet and overbite with modified Distal-Jet appliance. CONCLUSION: Modified Distal-Jet appliance can distalize maxillary molars effectively.