Sutural Distraction Osteogenesis (SDO) For Correction Of Midface Hypoplasia: Experimental And Clinical Studies

PartⅠEffect of Aging on Mechanical Properties of Facial SururesObjective The aim of the study is to determine the effect of aging on sutural interdigitation and nanomechanical properties of facial suture in order to provide a experimental basis for feasibility of applying sutural distraction osteogenesis in different ages.Method Using the digital photograghs of the suture specimens to measure the degree of sutural interdigitation and using the atomic force microcopy(AFM) with the nanoindentation method,the nanomechanical properties of four facial sutures-pre -maxillomaxillary(PMS),the nasofrontal(NFS).the zygomatico-temporal(ZTS),the transverse palatine(TPS) -and their corresponding sutural mineralization fronts in two groups of rabbits-3 month-aged and 6 month-aged,were measured and analyzed.Results The marked differences were found in the degree of sutural interdigitation between ZTS and NES.ZTS and PMS,NFS and PMS.ZTS and TPS.PMS ard TPS(p＜0.01),though no significant differences were found between NFS and TPS in 3 month-aged rabbits(p＞0.05).The degree of sutural interdigitation in NFS and TPS are lower than in PMS.though they are higher than in ZTS,while in 6 month rabbits,there are significant difference between all the four sutures and the relatice relation between them is PMS＞NFS＞TPS＞ZTS.There are marked difference between two groups of rabbit.The sutural interdigitation of NFS and PMS is increased with age,though ZTS and TPS were found no significant change with age.The topograghic images of four sutures and their corresponding sutural mineralization fronts are different.The topograghic images of 3 month aged rabbits,ZTS and its corresponding sutural mineralization front are smoother than PMS,NFS and TPS.Though in 6 month-aged rabbits.the topograghic images of PMS are rougher than ZTS.NFS and TPS.The NFS and TPS's topograghic images in 6 month-aged rabbits are smoother than 3 month-aged rabbits.The significant differences were found in the elastic modulus between ZTS and PMS.ZTS and TPS,NFS and PMS.NFS and TPS.though no significant differences were found between ZTS and NFS.PMS and TPS in 3 month-aged rabbits.Also PMS and TPS have higher elastic modulus than ZTS and NFS.The elastic modulus of sutural mineralization fronts followed the same distribution pattern as the elastic modulus of their corresponding sutures in 3 month-aged rabbits.The elastic modulus of sutures and their corresponding sutural mineralization fronts in 6 month-aged rabbits followed the same distribution pattern as the elastic modulus in 3 month-aged rabbits.The elastic modulus of the four facial and their corresponding sutural mineralization fronts in 6 month-aged group are higher than in 3 month-aged group.The average elastic modulus of the sutural mineralization fronts were significantly higher than their corresponding sutures in two groups.Conclusion Using the atomic force microscope can measure the topographic and nanoelastic property of the facial suture in a more natural way which helping us to research the biomechanical properties of the sutures.The elastic modulus of sutures and their corresponding sutural mineralization fronts were measured in order to investigate the relationship between them and the resistance center of maxilla.The changes of aging on the characteristics of the topographic and the elastic modulus of the suture may provide a experimental basis for feasibility of applying sutural distraction osteogenesis in different ages.PartⅡSutural Distraction Osteogenesis(SDO) for Midfacial Advancement in the Cleft lip and palate Patients With Maxillary Hypoplasia:Clinical studyObjective The preliminary research for applying niti-shaped memorial alloy distraction system for sutural distraction osteogenesis of midfacial advancement at different ages and efficacy evaluation.Methods we design springs and hooks made of niti-shaped memorial alloy and use the rigid external distracting device and continuous sutural distraction technical to treat 16 patients with midface hypoplasia after cleft lip and palate operation.12 patients are UCLP and 4 patients are BCLP.The average age of the patients is 12.6(10～19.5).We taked the photos,x-ray for cephalometry,CT,dental cast and nasopharyngeal fiberscope to evaluate the result after distraction and also evaluate the effects of treatment by statistical analysis.Results In our clinical study,14 patients were successfully teated with this technique.2 patients are still in the retention period.The follow-up period of these 14 patients is from 4 month to 3 years.13/14 patients achieved satisfactory face contour and normal occlusal relationship,but 2/14 patients have a slightly relapse with the anterior teeth turning into edge-to-edge occlusion within the follow-up period because of not enough over correction and short retention period or unstable retention device.We found the mid-face bone can maintain growing potential and continuously grom forward within the 1-year follow-up period.Only 1/14 patient had a totally relapse because of only 1 month retention for the first reason.The second reason is the patient underwent operation of correction for the secondar deformity of CLP at the same time when the RED is removed.The velopharyngeal function is evaluated after treatment and We found all but 2 patients had different degree of velopharyngeal insufficiency in the midanaphase of treatment which have different degree of recovery after retention period.There are significant statistical differences in any of the outcome measures of cephalometry between pre-treatment and post-treatment in 10/14 patients.Conclusions The sutural distraction osteogenesis is a kind of less invasive. accessory skeleton growth regenerative technique.Using the niti-shaped memorial alloy distraction system to cure the midface displasia deformity of the CLP patients,it can offer the opportunity for patients to correct the midface hypoplasia with a more simple,safer and effective method.