[ effect of spring loaded posterior occlusal bite-block on treatment of skeletal open bite]

One of the most difficult procedures in orthodontics is the treatment of skeletal open bite. This malocclusion is characterized by backward rotation of mandible, an obtuse gonial angle, an increased anterior facial height, and a long face appearance. The treatment strategy of skeletal open bite has been mainly based on vertical growth inhibition, forward autorotation of mandible, and intrusion of posterior dentoalveolar structures. Early treatment of this malocclusion is of great interest because the therapeutic approach is functional before growth has been completed and is surgical afterwards. Posterior bite-blocks are one of the functional appliances which are commonly used. The purpose of this study was to evaluate the effect of spring loaded posterior occlusal bite block [SLPOBB] on dento-facial structures in patients with skeletal open bite. In this clinical trial study, our sample group consisted of 23 skeletal open bite subjects [9 males and 14 females] having a mean age of 9.8, treated by SLPOBB until the open bite was completely dissolved and a favorable overjet was achieved. Cephalometric tracing was carried out on the lateral cephalograms taken prior to and after treatment. The data were analyzed using paired t-test to determine significant changes [alpha=0.05]. Skeletal changes: A statistically significant increase in SNB, ArGoGn, mandible length, anterior facial height, UFH, LFH, and posterior facial height was found. Decrease in ANB, Palatal plane/MeGo, SArGo, SNGoAr, and Y-Axis was also significant. Dental changes: The results revealed a significant increase in Upper1/Palatal plane height, Lower1/GoMe height and Upper6/Palatal plane height and a decrease in Lower1/GoMe angle. SLPOBB was found to be effective in treatment of skeletal open bite by: 1] A significant decrease of mandibular posterior angles, an increase of posterior facial height, and upward and forward rotation of mandible. 2] Intrusion of mandibular first molars. 3] Extrusion of anterior dentoalveolar height, and lingual inclination of lower incisors