Cone Beam Computed Tomography(CBCT)Study Of The Alveolar Bone Change For Combined Orthodontic-Periodontal Treatment

BACKGROUNDPeriodontal disease is an inflammatory, destructive disease which implicates in periodontal supporting tissue (includes gum, periodontal membrane, alveolar bone and cementum). Occlusal trauma resulting from many kinds of malocclusion is a very important local promoting factor. When people have periodontal disease which caused by plaqude, trauma plays a part of co-destruction. Elimination of occlusal trauma, cure malocclusion. aligning crowding teeth, retrusion anterior flaring teeth, adjustment occluding relation and occlusal force direction undergoing orthodontic treatment could create benign environment for periodontal tissue, which is an important comprehensive treatment for periodontal disease. But in clinical practice, we can see obvious attachment loss and increased teeth mobility even when the periodontal disease was controlled in a non-active condition. So it seems that the orthodontic treatment sometimes makes the periodontal disease more serious. But there are so little study about that.PURPOSEIn order to make sure the security of orthodontic treatment for periodontic,12samples were chosen for the combined periodontal-orthodontic therapy. The first stage of orthodontics including alignment and leveling arches was observed. CBCT was used to measure the alveolar bone density change during orthodontic treatment.METHOD12patients were chosen in Shandong Provincial Hospital Dept. Orthodontics (female8male4), which accept the CBCT exam before and after orthodontic treatment. The software "Easydent" was used to measure the alveolar bone density between incises, incise and lateral incise, lateral incise and canine. The study can analyze the law of alveolar bone density change and the difference between different teeth, evaluate the clinical effect of the treatment of combined periodontic-orthodontic therapy, in order to provide basis for clinical treatment.RESULT1. CBCT was an advanced technique by3D reconstructions from acquired volumetric data set, producing more precise data of alveolar bone density. Landmarks in the interest area were repeatable and results were reliable and comparable.2.The alveolar bone density decreased in different degree after the orthodontic treatment。3. There were no statistical significant differences between different teeth in the same jaw.4. The alveolar bone density in mandible was higher than maxillary, and the degree of decrease was also higher than maxillary.5. Individual patients after orthodontic treatment CBCT3D reconstruction images show the buccal bone plate disappear and individual teeth alveolar bone was found a vertical bone absorption.CONCLUSION1. CBCT was a noninvasive technique, providing a quantitative and accurate data. Landmarks of interest area were reproducible and the results were reliable, comparable and effective.2. The alveolar bone density decreased obviously even when the periodontal disease was under a non-active stage, which suggest the method used in our normal clinical practice was too heavy for the periodontitis, so the destruction of periodontal tissue was more than reconstruction.3. There were no significant difference between different teeth in the same jaw. That suggest that the reflection of alveolar bone in different teeth were almost the same under the same orthodontic force. 4. The alveolar bone density decrease degree was more significant in mandible than in maxillary, that is to say, mandible was more sensitive for the orthodontic treatment. This phenomenon maybe could be explained as buttressing bone formation in response to occlusion trauma, which was stress-susceptible and pathologic alveolar bone. The abnormal alveolar bone was easier to be absorbed than normal one. As for how long the alveolar bone density could recover, and whether it could recover to the initial stage were still problems for further study.5. Individual patients experienced alveolar bone vertical absorption.Speculation is due to use the method of orthodontic to lower imperfected dislocation tooth, because the periodontal ligament will have the drag effect and cause conical bone absorption, long and narrow infrabony pocket formed. There were3patients after orthodontic treatment CBCT3d reconstruction images showed the buccal bone plate disappear.The reasons of this phenomenon, on the one hand, is in the process of orthodontic, aligned teeth to reciprocating movement to come into line caused buccal bone plate absorbs, reduced bone mineral density, bone plate thickness thin, on the other hand, CBCT3D reconstruction will inevitably have part of the loss of image information, the thin alveolar bone in the reconstructed image can not display.