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The use of gradually increasing orthodontic force induces increased activity of osteoblasts during the initial stage of orthodontic tooth movement compared to that induced by a relatively constant orthodontic force.

Objective:Objective: Objective: Objective: The aim of this study is to investigate the effectiveness of the mini-plate zygomatic anchorage for intrusion of maxillary molars in adult skeletal anterior open-bite patients. Materials and Methods: Materials and Methods: Materials and Methods: Materials and Methods: The study group was composed of 10 anterior open-bite patients with posterior dentoalveolar excess. Placement of the mini-plates in the zygomatic buttress was carried out under local anaesthesia. After placement of a double TPA, a closed Ni-Ti coil spring was placed bilaterally between the hook of the mini-plate just mesial and distal to the first molar buccal tube applying intrusive force of 450g per side. Lateral cephalograms and posteroanterior radiographs were taken before intrusion (T1: post upper segmental leveling) and after intrusion (T2). The cephalometric films were measured and compared. Results:Results: Results: Results: The mean amount of accomplished molar intrusion was 3.1mm ± 0.74mm, with a rate of 0.36mm per month ± 0.08mm per month and a bite closure of 6.55mm±1.83mm. Mandibular autorotation followed the molar intrusion, SNB and SN-Pog angles significantly increased while the ANB, MP-SN angle and N-S-Gn angle significantly decreased. There was no significant buccal tip in the right and left molars. Conclusion: Conclusion: Conclusion: Conclusion: Zygomatic anchorage can be used effectively for skeletal open-bite correction through posterior dento-alveolar intrusion.

The objective of this study was to evaluate the canine retraction rate with two low-level laser therapy (LLLT) irradiation protocols, involving both a high and a low application frequency. Twenty patients were randomly divided into two equal groups. In Group A, one side of the maxillary arch randomly received LLLT on days 0, 3, 7, 14, and every 2 weeks thereafter, whereas in Group B, one side received LLLT every 3 weeks. Tooth movement was checked every three weeks since the onset of canine retraction, over the 12-week study period. Moreover, Interleukin-1β (IL-1β) levels in the gingival crevicular fluid were assessed. Results revealed a significant increase in the canine retraction rate on the laser sides of groups A and B, in comparison with the control sides (p < 0.05), with no significant differences reported between the laser sides in both groups (p = 0.08–0.55). Also, IL-1β levels were significantly higher on the laser sides of both groups, in comparison with the control sides (p < 0.05). Therefore, LLLT can effectively accelerate tooth movement, with both frequent and less frequent applications, which is attributed to an enhanced biological response as reflected by the elevated IL-1β levels on the compression sides.