A New Orthodontic Screw for Removable Bite Jumping Appliances

Abstract

AIM: To develop an advancement device that can be re-activated by the clinician without laboratory support to provide stepwise advancement up to 12 mm and have provision for opening of the posterior segments during advancement of the mandible. MATERIALS AND METHOD: In initial studies, a modified reciprocally expanding rapid palatal expander (RPE) orthodontic screw was incorporated into 40 split monobloc activators. Deficiencies with the modified RPE screw were encountered. To address this, a stronger component was developed. This device incorporated a machined rotating screw fixed to the maxillary appliance with a hinged carrier unit attached to the mandibular appliance. Simultaneously the posterior section of the appliance was allowed to separate occlusally according to the patient’s individual condylar movement. This improved screw design was tested in 10 split monobloc activator appliances and fitted to patients with skeletal Class II malocclusions. RESULTS: The improved appliance comfortably fitted to all patients, maintained protrusion and provided further advancement. No laboratory assistance was required. CONCLUSION: This improved device is a suitable mechanism for applying gradual advancement that is tolerated by patients.