Three-dimensional morphologic analysis of the maxillary alveolar bone after anterior tooth retraction with temporary anchorage devices.

OBJECTIVES: To investigate three-dimensional (3D) morphologic changes in the alveolar bone around the maxillary central incisors of patients who underwent premolar extraction and subsequent anterior tooth retraction using temporary anchorage devices (TADs). MATERIALS AND METHODS: The subjects consisted of 16 patients with bimaxillary protrusion. The maxillary anterior teeth were retracted using sliding or loop mechanics and TADs for anchorage reinforcement. Cephalograms and computed tomography scans taken pretreatment and posttreatment were registered with respect to the palatal structures. The movement of the maxillary central incisors and morphologic changes in the anterior alveolar bone were evaluated quantitatively. RESULTS: Displacement in the palatal direction was observed in the alveolar bone around the incisors and the interdental septum. The displacement and bone remodeling/tooth movement ratio were larger on the labial side than the palatal side, and decreased progressively from the crest to apex level. The bone thickness was significantly increased on the labial side and decreased on the palatal side. CONCLUSIONS: Regional differences exist in morphologic changes of the alveolar bone during anterior tooth retraction using TADs. Attention should be paid to the crest region of the palatal alveolar bone because of its small original thickness and low remodeling activity.

Effect of vibration on orthodontic tooth movement in a double blind prospective randomized controlled trial.

The purpose of the present study was to investigate the effect of vibration on orthodontic tooth movement and safety assessment based on our previous basic research in animal experiments. A double-blind prospective randomized controlled trial using split-mouth design was conducted in patients with malocclusion. The left and right sides of maxillary arch were randomly assigned to vibration (TM + V) and non-vibration (TM) groups. After leveling, vibrations (5.2 ± 0.5 g-forces (gf), 102.2 ± 2.6 Hertz (Hz)) were supplementary applied to the canine retracted with 100 gf in TM + V group for 3 min at the monthly visit under double-blind fashion, and the canine on the other side without vibration was used as TM group. The amount of tooth movement was measured blindly using a constructed three-dimensional dentition model. The amount of canine movement per visit was 0.89 ± 0.55 mm in TM group (n = 23) and 1.21 ± 0.60 mm in TM + V group (n = 23), respectively. There was no significant difference of pain and discomfort, and root resorption between the two groups. This study indicates that static orthodontic force with supplementary vibration significantly accelerated tooth movement in canine retraction and reduced the number of visits without causing side effects.

A comparative assessment of orthodontic treatment outcomes of mild skeletal Class III malocclusion between facemask and facemask in combination with a miniscrew for anchorage in growing patients: A single-center, prospective randomized controlled trial.

OBJECTIVES: To investigate the hypothesis that there is difference in the treatment outcomes of milder skeletal Class III malocclusion between facemask and facemask in combination with a miniscrew in growing patients. MATERIALS AND METHODS: Patients were randomly divided into two groups. In one group, the patients were treated with facemask therapy (FM group: 12 males, eight females, average age: 10 years, 5 months ± 1 year, 8 months). In the other group, patients were treated with facemask therapy along with a miniscrew (FM+MS group: 12 males, seven females, average age: 11 years, 1 month ± 1 year, 3 months). A lingual arch with hooks was fixed to the maxillary arch in both groups and a protractive force of 500 g was applied from the facemask to the hooks. The patients were instructed to use the facemask for 12 hours per day. In the FM+MS group, a miniscrew was inserted into the palate and fixed to the lingual arch. RESULTS: Mobility and loosening of the miniscrew were not observed during treatment. Lateral cephalometric analysis showed that SNA, SN-ANS, and ANB values were significantly increased in the FM+MS group compared with those for the FM group (SNA, 1.1° SN-ANS, 1.3° ANB, 0.8°). Increase in proclination of maxillary incisors was significantly greater in the FM group than in the FM+MS group (U1-SN, 5.0°). CONCLUSIONS: During treatment of milder skeletal Class III malocclusion, facemask therapy along with a miniscrew exhibits fewer negative side effects and delivers orthopedic forces more efficiently to the maxillary complex than facemask therapy alone.

Synergistic acceleration of experimental tooth movement by supplementary high-frequency vibration applied with a static force in rats.

Several recent prospective clinical trials have investigated the effect of supplementary vibration applied with fixed appliances in an attempt to accelerate tooth movement and shorten the duration of orthodontic treatment. Among them, some studies reported an increase in the rate of tooth movement, but others did not. This technique is still controversial, and the underlying cellular and molecular mechanisms remain unclear. In the present study, we developed a new vibration device for a tooth movement model in rats, and investigated the efficacy and safety of the device when used with fixed appliances. The most effective level of supplementary vibration to accelerate tooth movement stimulated by a continuous static force was 3 gf at 70 Hz for 3 minutes once a week. Furthermore, at this optimum-magnitude, high-frequency vibration could synergistically enhance osteoclastogenesis and osteoclast function via NF-κB activation, leading to alveolar bone resorption and finally, accelerated tooth movement, but only when a static force was continuously applied to the teeth. These findings contribute to a better understanding of the mechanism by which optimum-magnitude high-frequency vibration accelerates tooth movement, and may lead to novel approaches for the safe and effective treatment of malocclusion.