Yutaka Miyamoto
Tsurumi University, Japan
Biography:
His field of expertise is orthodontics. He is an active member of Japan Lingual Orthodontic Association (JLOA) and a qualified orthodontist of Japanese Orthodontic Society (JOS). He is an assistant professor at the Tsurumi University Department of Orthodontics and actively conducts clinical practice and research.
Abstract:
The modified Palatal Lever Arm System (PLAS) fixes the maxillary first molar via the PLAS from the mid-palatal miniscrews. It provides absolute anchorage to molars. In addition, tipping, rotation and any other side effects of the maxillary first molars are prevented. Moreover, it is possible to perform unique orthodontic tooth movements such as expand dental arch to unilateral side individually, which is considered to be difficult using conventional devices.
Case 1: The patient was a 25-years-old Japanese woman. Her chief complaint was upper teeth protrusion. The degree of overjet was 11.3 mm. Mandibular left second premolar was positioned lingually. Lateral cephalometric analysis showed a skeletal Class II jaw relationship. Maxillary both first premolars and mandibular left second premolar were extracted. Lingual multi-bracket appliances, mid-palatal miniscrews and modified PLAS were applied. The maxillary incisors were retracted with absolute anchorage of the maxillary both first molars. Proper overjet and overbite were achieved.
Case 2: The patient was a 20-years-old Japanese woman. Her chief complaint was crowding of upper teeth. The left molars showed crossbite, and the maxillary left lateral incisor was positioned lingually. The inter-canine Class II relationship was observed. Four first premolars were extracted. By activating the left arm of the PLAS to the buccal side, the left side of maxillary dental arch was expanded and crossbite of the left molars were corrected. The occlusal cusp-fossa relationship was established in the occlusion with Class I canine relationship