Intrusion of Overerupted Maxillary Molars with Miniscrew Implant Anchorage: A Radiographic Evaluation

The aim of this retrospective study was to quantitatively evaluate the treatment effects of in- trusion of overerupted maxillary molars using miniscrew implant anchorage and to investigate the apical root resorption after molar intrusion. The subjects included 30 patients whose average ages were 35.5±9.0 years. All patients had received intrusion treatments for overerupted maxillary molars with miniscrew anchorage. There were 38 maxillary first molars and 26 maxillary second molars to be in- truded. Two miniscrews were inserted in the buccal and palatal alveolar bone mesial to the overerupted molar. Force of 100-150 g was applied by the elastic chains between screw head and attachment on each side. Lateral cephalograms and panoramic radiographs taken before and after intrusion were used to evaluate dental changes and root resorption of molars. Only 6 of the 128 miniscrews failed. The first and second molars were significantly intruded by averages of 3.4 mm and 3.1 mm respectively （P〈0.001）. The average intrusion time was more than 6 months. The crown of the molars mesially tilted by averages of 3.1 degrees and 3.3 degrees （P〈0.001） for first and second molars. The amounts of root resorption were 0.2-0.4 mm on average. The intrusion treatment of overerupted molars with miniscrew anchorages could be used as an efficient and reliable method to recover lost restoration space for pros- thesis. Radiographically speaking, root resorption of molars was not clinically significant after applica- tion of intrusive forces of 200 to 300 g.

Extraction treatment of an adult patient with severe bimaxillary dentoalveolar protrusion using microscrew anchorage

Bimaxillary dentoalveolar protrusion is one of the most prevalent malocclusion in Asian population.Traditionally, orthodontic treatment often involves the extraction of four first premolars and demands the least amount of anchorage loss, therefore headgear used to be an unavoid- able fate of these patients. Nowadays, along with the development of implant anchorage, more and more patients have benefited from the implant-aided orthodontic treatment, even escaped from orthognathic surgery. However, for extremely severe cases, orthodontists seem to still have to face the limitation of orthodontic treatment and turn to surgeons for cooperation. In this case, we will see how dramatic changes happened on an adult patient with severe bimaxillary dentoalveolar protrusion malocclusion after the orthodontic treatment with microscrew implants as the temporary skeletal anchorage with the patient＇s written informed consent,