Prognostic factors for alveolar regeneration: effect of tissue occlusion on alveolar bone regeneration with guided tissue regeneration

OBJECTIVES: Design criteria for guided tissue regeneration (GTR) devices include biocompatibility, cell occlusion, space-provision, tissue integration, and ease of use. The objective of this study was to evaluate the effect of cell occlusion and space-provision on alveolar bone regeneration in conjunction with GTR. METHODS: Routine, critical-size, 6 mm, supra-alveolar, periodontal defects were created in 6 young adult Beagle dogs. Space-providing ePTFE devices, with or without 300-microm laser-drilled pores were implanted to provide for GTR. Treatments were alternated between left and right jaw quadrants in subsequent animals. The gingival flaps were advanced for primary intention healing. The animals were euthanized at week 8 post surgery. The histometric analysis assessed regeneration of alveolar bone relative to space-provision by the ePTFE device. RESULTS: A significant relationship was observed between bone regeneration and space-provision for defect sites receiving the occlusive (beta = 0.194; p < 0.02) and porous (beta = 0.229; p < 0.0004) GTR devices irrespective of treatment (p = 0.14). The bivariate analysis showed that both space-provision and device occlusivity significantly enhanced bone regeneration. Hence, sites receiving the occlusive GTR device and sites with enhanced space-provision showed significantly greater bone regeneration compared to sites receiving the porous GTR device (p = 0.03) or more limited space-provision (p = 0.0002). CONCLUSIONS: Cell occlusion and space-provision may significantly influence the magnitude of alveolar bone regeneration in conjunction with guided tissue regeneration.     

Prognostic factors for alveolar regeneration: effect of a space-providing biomaterial on guided tissue regeneration

OBJECTIVES: There is a limited understanding of the effect of bone biomaterials on the healing potential when used in conjunction with guided tissue regeneration (GTR). The objective of this study was to evaluate the effect of a space-providing coral-derived biomaterial on alveolar bone regeneration in conjunction with GTR. METHODS: Bilateral, critical-size, 6-mm, supra-alveolar, periodontal defects were created in four young adult Beagle dogs. In a split-mouth design, the animals received an ePTFE device to provide for GTR in contralateral defect sites with or without the coral biomaterial. The animals were euthanized at 4 weeks post surgery. A histometric analysis assessed vertical regeneration of alveolar bone relative to space-provision by the ePTFE device. Because of the correlation of within-dog measurements, a mixed model ANOVA was used to analyze the data. RESULTS: There was significantly greater mean bone regeneration in sites receiving calcium carbonate coral implant GTR (cGTR) compared to GTR (p < 0.0001). Sites providing larger wound areas exhibited greater bone regeneration compared to sites exhibiting smaller wound areas (p < 0.0001). However, grouping the sites by wound area thresholds showed that bone regeneration was not significantly different in sites receiving cGTR compared to sites receiving GTR alone, irrespective of the size of the wound area (p > 0.5). Conclusions: Space-provision has a significant effect on bone regeneration following GTR. The coral biomaterial effectively enhances space-provision, and this appears to be the principal mechanism by which this biomaterial supports bone regeneration rather than postulated osteoconductive properties.     

Augmentation of the rat jaw with autogeneic cortico-cancellous bone grafts and guided tissue regeneration

The aim of the present study was to evaluate the effect of augmenting the maxillary alveolar ridge and the lateral aspect of the mandible with onlay autogeneic cortico-cancellous bone grafts that were covered with e-PTFE membranes. The experiment was carried out in 51 rats. In 15 rats, the edentulous maxillary jaw between the incisor and the first molar was augmented by means of an autogeneic ischiac bone graft that was fixed with a gold-coated microimplant. In one side, the graft was covered with an e-PTFE membrane, while the other side, which served as control, was treated without a membrane. In the other 36 rats, the lateral aspect of the mandible was augmented in both sides by means of an autogeneic ischiac bone graft that was fixed with a gold-coated or a titanium microimplant. In one side, the augmented area was covered with an e-PTFE membrane, while the contralateral side was treated without a membrane. Histological analysis at 60, 120 and 180 days after augmentation of the maxilla showed that, in the case of the test sites (where most of the membranes were either exposed or lost), the bone grafts presented extensive resorption and there was a lack of bone continuity between the graft and the recipient site. Similar findings were made at the non-membrane-treated control sides. In the case of augmentation of the mandible with membranes, the bone grafts were not resorbed, but were integrated into newly formed bone at the recipient site. In the control sides, the grafts presented varying degrees of resorption and integration into the recipient bone. It is concluded that, in comparison to bone grafting alone, onlay ischiac bone grafting combined with guided tissue regeneration eliminates the risk of bone graft resorption and ensures integration of the graft into newly formed bone at the recipient site, provided that closure of the operated area can be maintained during healing.     

Bone regeneration using the principle of guided tissue regeneration

The biological principle of "guided tissue regeneration" (GTR) was developed for regenerating periodontal tissues, lost as a result of periodontal disease. This principle was based on the hypothesis that non-desirable types of tissue cells can be prevented from migrating into a wound by means of a membrane barrier and at the same time giving preference to those particular cells to repopulate the wound, which have the capacity to regenerate the desired type of tissue. This principle may have its application in many areas of surgery, aimed at regeneration of lost tissues. One such area is osseous surgery aimed at bone regeneration. In the present paper, a series of experiments in laboratory animals using the method of GTR for regeneration of various types of bone defects are presented as well as examples of application in humans for regeneration of jaw bone defects in conjunction with the placement of dental implants.     

牙槽突裂治疗方法的研究进展

牙槽突裂整复术现已成为唇腭裂序列治疗的重要环节,上颌骨裂隙骨移植在20世纪初就已提出,但至今,对牙槽突裂的治疗方法仍存在许多争议,本文就牙槽突裂整复术的手术时机、植入物选择、手术方法、术前术后正畸干预等方面的研究进展作一综述。     

牙槽突裂骨移植治疗进展

牙槽突裂骨移植是口腔颌面部裂隙畸形重建的重要步骤。初期肋骨移植能使上颌骨连续,消除口鼻腔瘘,不影响面中部发育,有助于防止双侧唇裂上颌骨节段性塌陷。二期髂骨移植成功率高,能稳定地产生小梁骨,恢复上颌骨连续性,提供正畸支持。牙槽突植骨能否产生足够的牙槽骨支持后期的正畸治疗,尚需进一步研究。本文就牙槽突裂骨移植治疗的进展作一综述。     

Digital subtraction radiography in assessing bone changes in periodontal defects following guided tissue regeneration

19 patients with a total of 23 periodontal lesions were selected for the study. Following flap-elevation, an occlusive membrane (Gore Tex) adjusted to the size and shape of the lesion was applied. The membrane was removed 4-6 weeks later by a 2nd operation. Clinical attachment levels were measured and intraoral radiographs taken prior to surgery, and 6 and 12 months postoperatively. The root length and marginal bone level were measured on paper drawings of the teeth magnified (15x) from the conventional radiographs. The radiographs were digitized for analysis of the subtraction images between the preoperative and the 6- and 12-month postoperative images. Clinical attachment gain was seen in 78% of the teeth after 6 months and 70% after 12 months. Bone gain was recorded in 56% and 22% after 6 months and in 44% and 66% after 12 months by conventional and digital subtraction radiography, respectively. The bone level measurements on conventional radiographs differed significantly (p = 0.001) between the preoperative and 6-month postoperative, but not between the 6- and 12-month, (p = 0.29) conventional radiographs. There was no significant relationship between the clinical measurements and the assessments of bone changes on conventional radiographs (r = 0.28, p = 0.25), while a stronger relationship was observed between assessment of clinical attachment gain and assessment of bone changes on the subtraction images (r = 0.58, p = 0.01).     

Evaluation of guided tissue regeneration in interproximal defects

Abstract This study clinically evaluates the use of expanded polytetrafluoroethylene (ePTFE) membranes with or without the addition of decalcified freeze-dried hone allograft (DFDBA) in the treatment of interproximal intraosseous defects, 25 patients (26 paired defects) diagnosed with advanced periodontitis and having at least 2 bilateral interproximal probing depths of s6 mm participated in the study. After the hygiene phase, measurements were made to determine soft tissue recession, pocket depth, and clinical attachment levels. Defects from each pair were randomly treated with either ePTFE alone (control), or ePTFE + DFDBA (experimental). Measurements were made during the surgery to determine crestal resorption, defect resolution and defect fill. Membranes were removed at 4 to 6 weeks. At 6 months, the soft and hard tissue measurements (surgical reentry) were repeated. Both groups showed statistically significant improvement when compared to baseline (p<0.001), but no difference was determined between groups. Control sites showed a 50% bone fill and experimental sites had 54% bone fill. The defect resolution changes were also similar between control and experimental groups, respectively (80%, 74%). For this short-term study, it was concluded that either technique was beneficial for the treatment of intraosseous defects. Other studies are needed to assess the long-term stability of the improvements rendered by these treatments.     

引导组织再生术诱导兔下颌骨正中缝骨融合的研究

目的观察引导组织再生术诱导发育性骨裂隙骨再生融合的作用,为引导组织再生术在唇腭裂骨性裂隙修复中的应用提供实验依据。方法将国产聚四氟乙烯膜盖于兔下颌骨正中缝唇舌两侧,通过放射和病理检查,观察骨缝融合的情况。结果引导组织再生术能在4周左右诱导骨裂隙完全骨融合。结论引导组织再生术是修复骨性裂隙的有效方法,有可能用于齿槽裂、跨裂的骨性修复。     

膜引导齿槽突裂骨缺损区组织再生的实验动物研究

目的 :评价膜引导齿槽突裂骨再生的效果。方法 :全麻下 ,分别在每组 2只兔双上颌形成人工齿槽突裂 ,随机作 :①聚乳酸 (PLA) 胶原 rhBMP 2膜覆盖 ;②PLA膜覆盖 ;③胶原膜覆盖 ;④空白对照。分别于术后 2周 ,1、2、3、6月处死动物切取标本 ,摄X线片 ,组织学观察 ,酶组化分析。结果 :膜覆盖骨裂 ,新生骨外形良好 ,骨改建成熟早 ,特别是PLA 胶原 rhBMP 2膜组 ,可持续控释rhBMP 2并提高骨缺损区浓度 ;空白对照组 ,生成骨质量、外形不良。结论 :引导组织再生膜具有促进齿槽突裂骨修复的作用。