| Objective: Dental implantation is an important treatment option for missing teeth.However,the clinical situation is often faced with insufficient bone mass in the implant area,and bone augmentation surgery is required to ensure enough bone mass around the implant.Autologous block graft is one important bone augmentation technique,has been widely used in the case of insufficient alveolar ridge bone mass.The apical region has been investigated as a bone donor site for block graft,which could avoid opening additional operative area to achieve minimally invasive operation.In this study,CBCT images of patients with maxillary incisor loss were collected and analyzed,to observe the size of maxillary incisor root apical region as a bone donor site.In addition,we evaluated the bone augmentation effect of apical bone extraction combined with GBR technique for block graft in beagle dog model including the width of alveolar ridge pre-and postoperation as well as the histological characteristics of the generated alveolar bone.Materials and methods: 1.Radiographic measurement study on the bone extraction from the apical region of the maxillary incisor for block graft.A total of 61 cases(2019.9-2019.12)of dentistry CBCT images of patients with missing incisors in the upper anterior region were collected from the Department of Stomatology,The First Affiliated Hospital of Dalian Medical University.Measurement range: the distal boundary of the bone extraction area is located 2mm from the root of the maxillary canine.The proximal border of the bone extraction area should be 2mm away from the midline,to avoid damage to the anterior nasal spine and shape of the face.The upper border of the bone extraction area should be located at the bottom of nasal cavity,to avoid damage to cortical bone at bottom of nasal cavity.When a single incisor was missing with the adjacent incisor on the same side had undergone complete root canal treatment in the bone extraction area,the lower boundary of the bone extraction area is located at the 2mm from the root tip of the remaining incisor.When all incisors were missing in the bone extraction area,the lower boundary of bone extraction was located at 8mm from the top of the alveolar ridge.The Demand 3D Dental software was used to measure and calculate the width and length of the bone block.We counted the number(N)of bone block: the length of the bone block is greater than 8mm,and the width is greater than mesiodistal diameter of the alveolar ridge of the natural tooth neck.We calculated the proportion of these bone blocks in all the measured bone blocks ? = N / 61 × 100%.2.Animal experimental study of bone harvesting from apical region for block graft.The beagle's premolars were removed and the animal model of tooth loss was established three months later.Block grafts were performed in the area of tooth loss.The apical region was used as the bone donor site.Guided Bone Regeneration(GBR)was performed at the same time.The buccal-lingual width of the alveolar ridge in the bone augmentation area was measured before operation,immediately after operation and 3 months after operation,Paraffin sections were prepared from the bone graft area,and histopathological observation was carried out on the bone augmentation area after HE staining and Masson staining.We evaluated the bone augmentation effect of apical bone extraction combined with GBR technique for block graft.Results: 1.Through the measurement and analysis of CBCT images,the average length of the bone in the apical region of the unilateral maxillary incisor was 11.10 ± 1.47mm(maximum of 15mm),and the average width of the bone was 8.36 ± 2.63mm(maximum of 16.75mm),The number and proportion of bone blocks that could be transplanted at the maxillary central incisor and lateral incisor were 50(81.97%)and 58(95.08%),respectively.2.In the Beagle dog animal model,the average alveolar ridge width before block grafting was 3.77 ± 0.57 mm,and the average alveolar ridge width immediately after operation was 5.46 ± 0.90 mm,and the average alveolar ridge width at 3 months after operation was 5.82 ± 0.94 mm.There was no significant difference in alveolar ridge width between the three months and immediately after operation(P = 0.383> 0.05).The width of the alveolar ridge increased significantly at 3 month and immediately after operation(P<0.05).3.In the beagle dog model,the bone augmentation was observed histologically at 3 months after block grafting: the newly mineralized bone,newly unmineralized bone and bone powder,no fibrous tissue was found in the bone augmentation area.Conclusion: 1.Through CBCT imaging measurement of the patients with anterior tooth loss,either a single upper incisor was missing with the adjacent incisor on the same side that had undergone root canal treatment or all unilateral upper incisors were missing,more than 81.97% of patients can harvest a bone block that meets the requirements of a single maxillary incisor implantation from the apical area of unilateral maxillary incisors.2.In beagle dog model,we measured the width of alveolar ridge and observed histological characteristics of the generated alveolar bone after three months operation.The results show that the apical bone extraction combined with GBR technique for block graft can achieve good bone augmentation effect,which is a feasible bone augmentation program. |
PDF Full Text Request