Celecoxib treatment does not alter recruitment and activation of osteoclasts in the initial phase of experimental tooth movement

In a previous study, we reported that the short-term treatment with celecoxib, a nonsteroidal anti-inflammatory drug (NSAID) attenuates the activation of brain structures related to nociception and does not interfere with orthodontic incisor separation in rats. The conclusion was that celecoxib could possibly be prescribed for pain in orthodontic patients. However, we did not analyze the effects of this drug in periodontium. The aim of this follow-up study was to analyze effects of celecoxib treatment on recruitment and activation of osteoclasts and alveolar bone resorption after inserting an activated orthodontic appliance between the incisors in our rat model. Twenty rats (400420 g) were pretreated through oral gavage with celecoxib (50 mg/kg) or vehicle (carboxymethylcellulose 0.4%). After 30 min, they received an activated (30 g) orthodontic appliance, set not to cause any palate disjunction. In sham animals, the appliance was immediately removed after introduction. All animals received ground food and, every 12 h, celecoxib or vehicle. After 48 h, they were anesthetized and transcardiacally perfused through the aorta with 4% formaldehyde. Subsequently, maxillae were removed, post-fixed and processed for histomorphometry or immunohistochemical analyses. As expected, incisor distalization induced an inflammatory response with certain histological changes, including an increase in the number of active osteoclasts at the compression side in group treated with vehicle (appliance: 32.2 +/- 2.49 vs sham: 4.8 +/- 1.79, P<0.05) and celecoxib (appliance: 31.0 +/- 1.45 vs sham: 4.6 +/- 1.82, P<0.05). The treatment with celecoxib did not modify substantially the histological alterations and the number of active osteoclasts after activation of orthodontic appliance. Moreover, we did not see any difference between the groups with respect to percentage of bone resorption area. Taken together with our previous results we conclude that short-term treatment with celecoxib can indeed be a therapeutic alternative for pain relieve during orthodontic procedures.

Experimental model of tooth movement in mice: A standardized protocol for studying bone remodeling under compression and tensile strains

During orthodontic tooth movement (OTM), alveolar bone is resorbed by osteoclasts in compression sites (CS) and is deposited by osteoblasts in tension sites (TS). The aim of this study was to develop a standardized OTM protocol in mice and to investigate the expression of bone resorption and deposition markers in CS and TS. An orthodontic appliance was placed in C57BL6/J mice. To define the ideal orthodontic force, the molars of the mice were subjected to forces of 0.1 N, 0.25 N, 0.35 N and 0.5 N. The expression of mediators that are involved in bone remodeling at CS and TS was analyzed using a Real-Time PCR. The data revealed that a force of 0.35 N promoted optimal OTM and osteoclast recruitment without root resorption. The levels of TNF-alpha, RANKL, MMP13 and OPG were all altered in CS and TS. Whereas TNF-a and Cathepsin K exhibited elevated levels in CS. RUNX2 and OCN levels were higher in TS. Our results suggest that 0.35 N is the ideal force for OTM in mice and has no side effects. Moreover, the expression of bone remodeling markers differed between the compression and the tension areas, potentially explaining the distinct cellular migration and differentiation patterns in each of these sites. (C) 2012 Elsevier Ltd. All rights reserved.

Angle class II correction with MARA appliance

Objective: To assess the effects produced by the MARA appliance in the treatment of Angle’s Class II, division 1 malocclusion. Methods: The sample consisted of 44 young patients divided into two groups: The MARA Group, with initial mean age of 11.99 years, treated with the MARA appliance for an average period of 1.11 years, and the Control Group, with initial mean age of 11.63 years, monitored for a mean period of 1.18 years with no treatment. Lateral cephalograms were used to compare the groups using cephalometric variables in the initial and final phases. For these comparisons, Student’s t test was employed. Results: MARA appliance produced the following effects: Maxillary growth restriction, no change in mandibular development, improvement in maxillomandibular relationship, increased lower anterior facial height and counterclockwise rotation of the functional occlusal plane. In the upper arch, the incisors moved lingually and retruded, while the molars moved distally and tipped distally. In the lower arch, the incisors proclined and protruded, whereas the molars mesialized and tipped mesially. Finally, there was a significant reduction in overbite and overjet, with an obvious improvement in molar relationship. Conclusions: It was concluded that the MARA appliance proved effective in correcting Angle’s Class II, division 1 malocclusion while inducing skeletal changes and particularly dental changes.

Dentoskeletal changes induced by the Jasper jumper and the activator-headgear combination appliances followed by fixed orthodontic treatment

Introduction: The aim of this study was to compare the dentoskeletal changes of patients with Class II Division 1 malocclusion treated with either the Jasper jumper appliance or the activator-headgear combination, both associated with fixed appliances. Methods: The sample comprised 72 subjects with Class II Division 1 malocclusion divided into 3 groups: group 1 included 25 subjects treated with fixed appliances and the force modules of the Jasper jumper at an initial mean age of 12.72 years, group 2 included 25 subjects treated with the activator-headgear combination followed by fixed appliances at an initial mean age of 11.07 years, and group 3 included 22 untreated subjects at an initial mean age of 12.67 years. Initial cephalometric characteristics and dentoskeletal changes were compared with analysis of variance. Results: Both experimental groups had similar dentoskeletal changes: restrictive effect on the maxilla, clockwise mandibular rotation and a slight increase in anterior face height, retrusion of the maxillary incisors, distalization of the maxillary molars, protrusion of the mandibular incisors, extrusion of the mandibular molars, and significant improvements of the maxillomandibular relationship, overjet, overbite, and the molar relationship. Conclusions: The effects of the Jasper jumper and the activator-headgear combination followed by fixed orthodontic appliances were similar in Class II malocclusion treatment.

The impact of healing time before loading on orthodontic mini-implant stability: a histomophometric study in minipigs

Objective: To evaluate healing time before loading, areas compression and tension and location of insertion on mini-implant stability. Design: Six minipigs were used. Each animal received 3 mini-implants in each quadrant: 1 mini-implant was used as an unloaded control (G1, n = 24); the other 2 were loaded with 150 g-force at three time intervals (G2: immediate loading, G3: after 15 days and G4: after 30 days), with 16 mini-implant in each experimental group. After 120 days, tissue blocks of the areas of interest were harvested. Clinical analysis (exact Fisher test) determined the survival rate. Histological analysis (Kontron KS 300TM, Zeiss) quantified the fractional bone-toimplant contact (%BIC) and bone area (%BA) at each healing time point, areas of interest, and insertion site (ANOVA and t tests for dependent and independent samples). Results: The mini-implant survival rates were G1: 71%, G2: 50%, G3: 75% and G4: 63%, with no statistical differences between them. The groups presented similar %BIC and %BA. There were no differences between the compression and tension sides or maxillary and mandibular insertion sites. Conclusions: These results suggest that low-intensity immediate or early orthodontic loading does not affect mini-implant stability, because similar histomorphometric results were observed for all the groups, with partial osseointegration of the mini-implants present.

Evaluation of the stability of open bite treatment using a removable appliance with palatal crib combined with high-pull chincup

OBJECTIVE: The aim of this prospective study was to cephalometrically analyze the stability of dentoalveolar and skeletal changes produced by a removable appliance with palatal crib associated to high-pull chincup in individuals with anterior open bite treated for 12 months, and compare them to individuals with similar malocclusion and age, not submitted to orthodontic treatment, also followed for the same period. METHODS: Nineteen children with a mean age of 9.78 years old treated for 12 months with a removable appliance with palatal crib associated with chincup therapy were evaluated after 15 months (post-treatment period) and compared with a control group of 19 subjects with mean age of 9.10 years with the same malocclusion that was followed-up for the same period. Seventy-six lateral cephalograms were evaluated at T1 (after correction) and T2 (follow-up) and cephalometric variables were analyzed by statistical tests. RESULTS: The results did not show significant skeletal, soft tissue or maxillary dentoalveolar changes. Overall, treatment effects on the experimental group were maintained at T2 evaluation with an increase of 0.56 mm in overbite. Overjet and maxillary incisors/molars position (vertical and sagittal) remained essentially unchanged during the study period. Only mandibular incisors showed significant changes (labial inclination and protrusion) compared to control group. CONCLUSIONS: Thus, it can be concluded that the early open bite treatment with a removable appliance and palatal crib associated with high-pull chincup therapy provided stability of 95%.