Absolute Bone Support-type Rapid Maxillary Expansion Of Animal Studies

The traditional teeth-borne rapid maxillary expansion (TB-RME) is anchoraged by teeth to expand the midpalatal suture. Patients who are younger than 12 years will achieve good results, when they receive TB-RME. Unfortunately, to adult, teeth anchorage can lead to unwanted effects, such as teeth tipping and extrusion, roots resorption, alveolar ridge crest and no rigid anchorage to hold the suture widen effects. Recent years, absolutely bone-borne rapid maxillary expansion (BB-RME) is a new treatment to adult transverse maxillary deficiency. Because of palatal ossteointegrated implants used as the ideal anchorage, forces occurring during RME can be directly transmitted to the bone to reduced side-effects. However, BB-RME is accompanied with presurgical bilateral osteotomy and fracture of the midpalatal suture to release the resistance of cranial bone. Patients and their orthodontists may feel that the malocclusion is not sufficiently disfiguring or functionally compromising to justify the risks and costs of a surgical procedure.In our research, we established the BB-RME animal model with nosurgical assisted split and evaluated the feasibility. Then we compared the difference results between the BB-RME and the TB-RME with non-surgical assisted split. Last the extent of anchorage teeth root resorption was observed.From our study, we observed the efficiency of BB-RME was higher than TB-RME in adult mini-pig. After TB-RME, the animal's anchorage teeth were underwent severe damage. The result of this present study was expected to provide more foundation data to clinical studyPart oneSelection of the optimum laboratory animal for absolutely bone-borne rapid maxillary expansionObjective: To select the optimum laboratory animal for BB-RME.Methods: Compare the skull of the New Zealand white rabbits, cats, beagle dogs and GuangXi bama mini-pigs. Observe the maxillary complex and measure the thickness of palate and mucous membrane.Result: The maxillary complex of non-human primates animal is most similar to the human; GuangXi bama mini-pig has ideal the thickness of palate.Conclusion: 22-month-old GuangXi bama mini-pig is ideal laboratory animal for absolutely bone-borne rapid maxillary expansion.Part TwoEstablishment of animal model of absolutely bone-borne rapid maxillary expansionObjective: To establish BB-RME animal model.Methods: Four 22-month-old female miniature pigs were used. One animal was served as untreated controls. Three animals were used tooth-borne RME. The appliance was expanded average 1.0 mm per adjustment. After 12 days adjustment, the total extension was 12 mm and the period of early retention was 30 days.Result: The mid-palatal suture was expanded successfully.Conclusion: Successfully establish the BB-RME animal model.Part threeComparison between absolutely bone-borne rapid maxillary expansion and tooth-borne rapid maxillary expansion in adult mini-pigsObjective: To compare and evaluate the efficiency of BB-RME with TB-RME.Methods: eight 22-month-old female miniature pigs were used. One animal was served as untreated controls. Three animals were used tooth-borne RME. Four animals were treated by bone-borne RME. The appliance was expanded average 1.0 mm per adjustment. After 12 days adjustment, the total extension was 12 mm and the period of early retention was 30 days. Standardized occlusal radiographs were taken periodically and analyzed for the changes of tooth and bone.Result: The palatal mid-suture were successfully expanded in two groups and statistically significant greater in bone-borne RME than those in tooth-borne RME in mature suture. Conclusion: To adult animal, the BB-RME is more efficient than the TB-RME.Part FourObservation of damage on the mini-pig's anchorage teeth root surface during teeth-borne rapid maxillary expansionObjective: To compare and evaluate the damage of anchorage teeth in BB-RME with TB-RME.Methods: analyze 48 anchorage teeth through histomophometrically evaluation. The root resorption area, number of odontoclasts, osteoclasts, mononuclear cells on root surface, tartrate-resistant acid phosphatase. (TRAP)-positive on the root, bone, and in the periodontal ligament (PDL) were compared between TB-RME and BB-RME animals.Result: significant increase in root resorption, the number of odontoclasts, mononuclear cells on root surface, and TRAP-positive cells on the root, PDL and bone for TB-RME group.Conclusion: To adult animal, TB-RME can induce more active damage of anchorage teeth.