Abstract
Abstract The intrusion of the maxillary first molar is indicated when occlusal clearance is needed for prosthetic rehabilitation. Maxillary molar intrusion may be undertaken using skeletal anchorage systems to avoid complicated mechanics delivered by conventional intra-oral fixed appliances. In the present case report, the efficient use of orthodontic miniscrew anchorage by applying simple mechanics for true maxillary first molar intrusion is described. This was followed by the rehabilitation of the mandibular first molar spaces with implant prostheses. A 16-year-old female patient had masticatory difficulty due to the bilateral overeruption of the maxillary first molars and carious mandibular first molars. True intrusion of each maxillary first molar was achieved using zygomatic and palatal paramedian miniscrews placed in line with the central axis of the teeth. Simultaneously, alignment of the upper arch was achieved via fixed appliance therapy. Using two orthodontic miniscrews to intrude each maxillary molar, orthodontic treatment was simplified by eliminating the need for miniplate placement by extensive surgery and the creation of intra-oral multiunit anchorage. Masticatory efficiency was improved by increasing the occlusal table with prosthetic rehabilitation of the mandibular first molar spaces with dental implant prostheses.
Highlights
Caries involvement of the permanent mandibular first molars in childhood can result in a number of problems should the teeth require extraction
From the biomechanical perspective, it is important to ensure that the line of applied intrusive force is perpendicular to the occlusal plane in a gingival direction and passes through the centre of resistance (Cres) of the molar so that true intrusion occurs without undesired tipping or rotation.[7]
A total of 200 g of intrusive force was applied to each maxillary first molar by the activation of the NiTi closed coil spring tied to the buccal and palatal miniscrews
Summary
Caries involvement of the permanent mandibular first molars in childhood can result in a number of problems should the teeth require extraction. Some clinicians prefer reducing and reshaping the crown of the overerupted maxillary molar (followed by root canal treatment in many cases) to create space for the prosthetic rehabilitation of the mandibular molars. Because of the increased versatility of skeletal anchorage systems, the use of miniplates, miniscrews and prosthetic implants to provide absolute anchorage for maxillary molar intrusion has been reported.[4,5,6]. From the biomechanical perspective, it is important to ensure that the line of applied intrusive force is perpendicular to the occlusal plane in a gingival direction and passes through the centre of resistance (Cres) of the molar so that true intrusion occurs without undesired tipping or rotation.[7].
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