大鼠骨髓基质细胞与胶原复合后修复牙槽骨缺损的研究

目的：探寻以大鼠骨髓基质细胞为种子细胞和胶原复合物为支架材料,构建组织工程骨的原理和方法修复齿槽骨缺损。方法：将SD大鼠骨髓基质细胞（Bone Marrows Stromal Cell,BMSc）进行体外培养并利用矿化液诱导为成骨样细胞,加入胶原（collagen）培养1d后,植入大鼠下颌骨缺损处,2周和4周后处死,取其下颌骨切片,观察成骨效应。结果：术后2周实验侧缺损区可见骨小梁形成,而对照侧无明显骨修复,4周后实验侧新骨形成量逐渐增加,而对照侧只有一些纤维组织修复。HE染色和mallory三色法染色结果也表明实验侧有新骨形成且逐渐增多。结论：应用胶原加体外诱导的成骨样细胞复合体移植可修复大鼠自体的牙槽骨缺损,为组织工程化骨在颌面外科及修复科领域的临床应用奠定了基础。     

Bone formation after sinus augmentation with engineered bone

Objectives: The aim of the following investigation was to quantify the resorption rate of tissue-engineered bone grafts in the maxillary sinus using volume measurements. MATERIAL AND METHODS: Sinus floor augmentation using autologous bone grafts from the iliac crest (n=17, group 1) was compared with commercially produced transplants of human cells seeded on polyglycolid-polylactid (PLGA) scaffolds (Oral Bone) (n=14, group 2). RESULTS: The total resorption rate for autologous transplants 3 months post operation was 29%, while the tissue-engineered bone showed a resorption rate of 90%. The autologous bone had a bone density of up to 266-551 Hounsfield units (HU), while sufficient mineralization of tissue-engineered bone was found in only one case (152 HU). CONCLUSION: In this clinical study, the use of autologous cancellous bone grafts in sinus augmentation was more reliable than scaffolds containing cultured osteoblasts. Further tissue-engineered bone transplants should be examined to draw general conclusions about the use of tissue-engineered grafts compared with autologous bone grafts for maxillary sinus augmentation.     

Lateral alveolar ridge augmentation using a synthetic nano-crystalline hydroxyapatite bone substitution material (Ostim): preliminary clinical and histological results

OBJECTIVES: The purpose of this preliminary two-center clinical prospective study was to evaluate the tissue composition of augmented sites after the use of a nano-crystalline hydroxyapatite (ncHA) bone substitution material by clinical and histological examinations. MATERIAL AND METHODS: A synthetic ncHA augmentation material was used without any additives in 14 patients requiring lateral ridge augmentation 6-7 months before (10 patients) or at implant placement (four patients). The ncHA material was covered by a titanium mesh for space maintenance. Clinical and radiographic parameters were evaluated and bone biopsy cores, obtained 6-7 months following augmentation, were assessed histologically and histomorphometrically. RESULTS: One patient showed gingival swelling, redness and pain at the augmentation site requiring removal of the titanium mesh 6 weeks postoperatively. In seven patients, a premature exposure of the titanium mesh without any inflammatory symptoms was noted. The width of the fixed gingival and the alveolar ridge height did not change significantly at least 6 months following augmentation (P>0.5), whereas a significant gain in alveolar ridge width (P=0.01) was noted. After a median period of prosthetic loading of 24 months, no implant was considered to be a failure. Histology revealed ncHA remnants in peripheral and central parts of biopsy cores obtained from seven patients after at least 6 months without histological symptoms of inflammation, whereas histomorphometry of bone cores revealed no significant differences of the mean percentage area of ncHA in peripheral (23.4%) and central (15.1%) parts of biopsy cores (P=0.262). The mean percentage area of bone colonizing the defect was 52.3%. CONCLUSIONS: Small amounts of ncHA were found after at least 6 months in bone biopsies. The former defect space was filled with bone. The alveolar ridge width gain was found to be significant after lateral augmentation utilizing ncHA, providing a quantitatively and qualitatively sufficient site for primary stable implant placement.     

Reconstruction of curved mandibular angle defects using a new internal transport distraction device: an experiment in goats

A new internal distraction device, comprising a square-bodied bow, a transport plate, a traction mechanism, and two stabilisers, was developed to allow transportation of bone around an arc. Eight adult goats were studied. A curved mandibulectomy 3cm long was made on the mandibular angle. The distractor was implanted to restore the defect. The bone was distracted at a rate of 1mm per day after a 5-day latent period. Distraction lasted 25 to 32 days. Curvilinear distraction was successful in six of the eight goats. After consolidation periods of four or eight weeks, smooth curved bone masses were restored in the distracted areas. Radiographically, there was considerable bone density in the distraction area and opaque columns streamed in the direction of distraction. Histological examination showed membranous bony regeneration in the restored bone. These results suggest that restoration of curved bone defects using the new internal transport distraction device was feasible in goats.     

Healing of onlay mandibular bone grafts covered with collagen membrane or bovine bone substitutes: a microscopical and immunohistochemical study in the sheep

The objective of this study was to evaluate the role of collagen membrane and Bio-Oss coverage in healing of an onlay graft to the mandible. Twelve adult sheep each received an onlay bone graft (experiment 1), bone graft+Bio-Gide (experiment 2), and bone graft+Bio-Oss/Bio-Gide (experiment 3) on the lateral surface of the mandible. The animals were euthanized at 4, 8, 12 or 16 weeks after surgery, and findings were analysed by routine microscopy and immunohistochemistry for proliferation (Ki67) and apoptotic (Caspase-3) markers. Grafts were fully incorporated in all specimens. Pronounced resorption was observed in experiment 1. Minimal loss of graft volume was seen in experiment 2 specimens without membrane displacement. A remarkable increase in the augmented region of the mandible was observed in experiment 3. A high number of osteoclasts were expressed within the grafts during the early healing period, and thereafter declined markedly. Osteoblasts within the grafts expressed a moderate level of Ki67 at 8 weeks, which thereafter declined markedly. The strongest expression of Caspase-3 on the bone surface was observed after 16 weeks. In conclusion, the effect of collagen membrane coverage on bone graft volume maintenance was dependent on membrane stability during healing. An autogenous bone graft covered with Bio-Oss particles resulted in a remarkable increase in augmented lateral surface of the mandible. The late stage of bone graft healing was associated with a high apoptotic induction pathway of osteoblasts lining the surfaces of the new bone, demonstrated by strong positive Caspase-3 immunoreactivity.     

影响人工骨植入隆鼻术效果若干问题的探讨

对影响致密多晶羟基磷灰石微粒人工骨植入隆鼻术效果的有关问题，如材料粒度的选择、植入床的设计和手术操作中的误差等进行了探讨，并提出了应注意的有关事宜。     

The effects of an immediately pre-surgical chlorhexidine oral rinse on the bacterial contaminants of bone debris collected during dental implant surgery

Dental implant surgery produces bone debris that can be used in the "simultaneous augmentation" technique. Although this debris is contaminated with oral bacteria, a stringent aspiration protocol has been shown to reduce the levels of contamination. Chlorhexidine mouthrinse is a well-proven antibacterial rinse that has been shown to reduce infectious complications associated with dental implants. This study examined the effect of pre-operative rinsing with a 0.1% chlorhexidine digluconate mouthrinse on the bacterial contaminants present in collected bone debris bone (CBD). Twenty partially edentate patients were randomly allocated into equal groups and underwent bone collection using the Frios Bone Collector (FBC) during the insertion of two dental implants. In group T a pre-operative chlorhexidine rinse was used, whilst in group C sterile water was used. For both groups, a stringent bone collection protocol was used. Bone samples were immediately transported for microbial analysis. Colonial and microscopic morphology, gaseous requirements and identification kits were utilised for identification of the isolated microbes. Thirty-nine species were identified including a number associated with disease, in particular Actinomyces odontolyticus, Clostridium bifermentans, Prevotella intermedia, and Propionibacterium propionicum. Samples from group T (chlorhexidine mouthrinse) yielded significantly fewer organisms (P < 0.001) than in group C (sterile water mouthrinse). Gram-positive cocci dominated the isolates from both groups. It is concluded that if bone debris is to be used for the purpose of immediate simultaneous augmentation, a preoperative chlorhexidine mouthrinse should be utilised in conjunction with a stringent aspiration protocol to reduce further the bacterial contamination of CBD.     

Use of a composite pedicled muscle flap and rhBMP-7 for mandibular reconstruction

The aim of this study was to investigate the feasibility of reconstructing critical size continuity osteoperiosteal defects of the mandible using a composite of recombinant BMP-7 contained in a bovine type-1 collagen carrier wrapped in a pedicled sterno-occipitalis muscle flap. At 3 months following surgery, bridging of the surgical defect was noted in three subjects (60%). Histologically, the induced bone regenerate showed maturation from woven to lamellar bone. Islands of cartilage were distributed throughout the defect. Replacement ossification of the degenerated muscle was a common feature in all specimens. Microradiography showed a gradual increase in the calcification of mineralized tissue from the margin to the centre of the newly generated bone. This research represents a proof of the concept that bone can be satisfactorily formed within a muscular scaffolding at the site of the created defect in a one-stage procedure.     

Dental implants placed in grafted maxillary sinuses: a retrospective analysis of clinical outcome according to the initial clinical situation and a proposal of defect classification

Objective of the study: To present a classification of maxillary defects necessitating sinus floor elevation procedures (SFEPs) with two objectives: (a) to propose a standardization of surgical procedures according to initial type of atrophy and (b) to allow the evaluation of the success/survival rates of implants placed in the grafted areas according to the initial situation. Materials and methods: Nine‐hundred and fifty‐two consecutive SFEP were performed on 692 patients. Initial defects were classified according to a new classification, which considered not only residual bone height below the sinus but also the width of the alveolar crest and horizontal/vertical intermaxillary relationship. Results were evaluated according to the different classes. The sinuses were grafted with autogenous bone taken from intra‐oral or extra‐oral sites: 579 SFEP were associated with vertical and/or horizontal onlay grafts to correct concomitant alveolar ridge deficits. A total of 2037 implants were inserted into the grafted sinuses either immediately or 4–6 months later. Three to 6 months afterwards, implants were loaded. The mean follow‐up was 59 months (range: 12–144 months). Results: The success rate of the reconstructive procedures varied between 93.2% and 100%, according to class of atrophy; the overall survival and success rates of implants were 95.8% and 92.5%, respectively, whereas the survival and success rates according to class of atrophy varied between 90% and 97.6%, and between 85.4% and 95.5%, respectively. Lower success rates were found in classes presenting with more severe atrophy. Conclusion: The results obtained demonstrated that sinus floor elevation, alone or in association with reconstructive procedures with autogenous bone grafts, is a reliable procedure to allow implant placement in atrophic edentulous maxillae, irrespective of the initial clinical situation. However, it must be underlined that the success rates of reconstructive procedures and implants differ according to class of atrophy, showing lower success rates in classes presenting with more severe atrophy.     

Attachment loss with postmenopausal age and smoking

To determine whether postmenopausal bone loss and factors associated with osteoporosis affect tooth retention, we examined vertebral and proximal femoral (postcranial) bone mineral density in relation to tooth loss and attachment loss in a cross-sectional study of 135 postmenopausal women (age range 41–70 yr). Women had at least 10 teeth and no evidence of moderate or severe periodontal disease. Full-mouth attachment loss measurements were made using a pressure-sensitive probe, and bone density was determined by dual-energy X-ray absorptiometry. Attachment loss was correlated with tooth loss (number of remaining teeth, radiologically determined), but not with vertebral or proximal femur bone density. Multivariate analysis showed current smoking (p = 0.01), years since menopause (p = 0.02) and the interaction of age and current smoking (p < 0.01), to be statistically significant predictors of attachment loss in our study population.