Alveolar bone regeneration for immediate implant placement using an injectable bone substitute: an experimental study in dogs

BACKGROUND: The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute for bone regeneration around dental implants placed into fresh extraction sockets. METHODS: Third and fourth mandibular premolars were extracted from three beagle dogs and the interradicular septa were surgically reduced to induce a mesial bone defect. Thereafter, titanium implants were immediately placed. On the left side of the jaw, mesial bone defects were filled with an injectable bone substitute (IBS), obtained by combining a polymer and biphasic calcium phosphate ceramic granules. The right defects were left unfilled as controls. After 3 months of healing, specimens were prepared for histological and histomorphometric evaluations. RESULTS: No post-surgical complications were observed during the healing period. In all experimental conditions, histological observations revealed a lamellar bone formation in contact with the implant. Histomorphometric analysis showed that IBS triggers a significant (P<0.05) increase in terms of the number of threads in contact with bone, bone-to-implant contact, and peri-implant bone density of approximately 8.6%, 11.0%, and 14.7%, respectively. In addition, no significant difference was observed when number of threads, bone-to-implant contact, and bone density in the filled defects were compared to the no-defect sites. CONCLUSION: It is concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate significantly increases bone regeneration around immediately placed implants.     

Immunohistochemical characterization of guided bone regeneration at a dehiscence-type defect using different barrier membranes: an experimental study in dogs

Objectives: The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes. Material and methods: Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen‐coated bone grafting material (BOC) in combination with either a native, three cross‐linked, a titanium‐reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin – OC, transglutaminase II – angiogenesis) and histomorphometrical analysis [e.g., bone‐to‐implant contact (BIC), area of new bone fill (BF)]. Results: In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10–12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group. Conclusion: Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level.     

Alveolar crest height and alveolar bone density in experimental osteopenia

General and alveolar osteopenia was provoked in young rats by Ca and /or deficiency. The alveolar bone density was assessed histometricall, the alveolar crest height between lower molars 1and 2 histometrically and/or radiographically. During the periods of the experiments no change fo the alveolar crest height was induced by the osteopenia. This fact is discussed against the background fo microscopic observations and previous reports.     

应用胶原骨材料进行引导性骨再生手术治疗前、后骨密度变化的临床研究

目的应用胶原骨行引导性骨再生手术,对比手术后拔牙创愈合情况及术前、术后1、4个月牙槽骨密度的变化。方法对慢性牙周炎需要进行位点保存手术的患者15例(共21颗患牙),通过临床检查比较拔牙创愈合情况,利用PLANMECA数字化曲面体层机软件分析系统对牙槽嵴顶以及牙冠部分的灰度值进行测量,采用单因素方差分析对比手术前后牙槽骨密度的改变量。结果术前、术后1个月、术后4个月三组的牙槽嵴骨密度值各为0.35±0.06、0.43±0.03、0.54±0.04,两两比较均有统计学意义(P<0.01)。结论应用胶原骨进行引导性骨再生手术术后牙槽骨密度较术前明显增加,能为Ⅱ期早期种植及最终的美学修复创造有利条件。     

Lethal photosensitization and guided bone regeneration in treatment of peri-implantitis: an experimental study in dogs

The purpose of this study was to evaluate the effect of lethal photosensitization and guided bone regeneration (GBR) on the treatment of ligature-induced peri-implantitis in different implant surfaces. The treatment outcome was evaluated by clinical and histometric methods. A total of 40 dental implants with four different surface coatings (10 commercially pure titanium surface (cpTi); 10 titanium plasma-sprayed (TPS); 10 acid-etched surface; 10 surface-oxide sandblasted) were inserted into five mongrel dogs. After 3 months, the animals with ligature-induced peri-implantitis were subjected to surgical treatment using a split-mouth design. The controls were treated by debridment and GBR, while the test side received an additional therapy with photosensitization, using a GaAlAs diode laser, with a wavelength of 830 nm and a power output of 50 mW for 80 s (4 J/cm2), and sensitized toluidine blue O (100 microg/ml). The animals were sacrificed 5 months after therapy. The control sites presented an earlier exposition of the membranes on all coating surfaces, while the test group presented a higher bone height gain. Re-osseointegration ranged between 41.9% for the cpTi surface and 31.19% for the TPS surface in the test sites; however differences were not achieved between the surfaces. The lethal photosensitization associated with GBR allowed for better re-osseointegration at the area adjacent to the peri-implant defect regardless of the implant surface.     

膜引导骨组织再生技术应用于即刻种植的实验研究

目的:探讨膜引导骨组织再生技术(membrane guided bone regeneration,mGBR)在即刻种植中的应用。方法:16颗钛75种植体种植于犬下颌第3、4前磨牙新鲜拔牙创,左侧(实验侧)置胶原膜,右侧无膜对照,术后4周、12周通过形态学和定量组织学分析研究种植体骨界面。结果:全部实验动物伤口愈合良好,术后4周和12周实验侧新骨形成均多于对照侧;实验测种植体直接骨接合率(DCLF,%)分别为32.93±2.66和65.95±7.00,对照侧为21.71±3.20和45.72±3.51。组间比较P<0.01。结论:mGBR可提高即刻种植成功率。     

In vivo experimental study on bone regeneration in critical bone defects using an injectable biodegradable PLA/PGA copolymer

OBJECTIVES: An assessment was done of the bone-healing rate after implantation of a polylactide/polyglycolide copolymer (PLA-PGA) 50/50 dispersed in aqueous solution of PGA and dextran, used as bone substitutes in an animal model. STUDY DESIGN: Two groups of 5 rabbits each were used. In both the femoral condyles, a critical size defect of 6x10 mm was made. On the right side PLA/PGA was inserted; the left side remained empty. Thirty and 90 days after surgery the animals were killed. RESULTS: Defects left unfilled showed no spontaneous healing after 30 and 90 days. Sites filled with experimental materials showed new bone ranging between 11.46% and 76.82% after 30 days, and 75.98% and 95.34% after 90 days. Histomorphometry showed an increase in bone maturation between day 30 and 90 in experimental sites. At day 90, no statistical difference was seen as compared to normal bone. CONCLUSION: PLA/PGA copolymer dispersed in hydrosoluble matrix seems to be suitable as osteoconductive material in critical size defects.     

Biological properties of an anti‐bacterial membrane for guided bone regeneration: an experimental study in rats

Objective: The biosafety and efficacy of silver–hydroxyapatite–titania/polyamide nanocomposite (nAg–HA–TiO₂/PA) membrane as a guided bone regeneration (GBR) barrier were investigated based on a rat subcutaneous and critical‐size calvarial defect model. Material and methods: Thirty‐six Sprague–Dawley albino rats were divided into nAg–HA–TiO₂/PA membrane test, expanded polytetrafluoroethylene (e‐PTFE) membrane control and blank control. Inflammatory response and bone regeneration in each group were evaluated using morphological, serological, radiographic and histological techniques at 1, 4 and 8 weeks, respectively, after implantation. Results: For subcutaneous implantation, slight degradation of nAg–HA–TiO₂/PA membranes was observed by scanning electron microscope at 4 and 8 weeks. Histopathologic examination demonstrated a thinner layer of granulation tissue in the vicinity of nAg–HA–TiO₂/PA membranes than that of e‐PTFE membranes. For cranial defect implantation, the serum alkaline phosphatase level was remarkably higher in nAg–HA–TiO₂/PA group than that in e‐PTFE group. Radiographic and histomorphometric analysis showed a fully closed cranial defect for both nAg–HA–TiO₂/PA and e‐PTFE groups at 8 weeks. No remarkable difference was found between the two groups regarding the integral optical density of neo‐bone at each time interval. Conclusion: nAg–HA–TiO₂/PA membranes demonstrated better biocompatibility and similar osteoinductive activity compared with e‐PTFE membranes. nAg–HA–TiO₂/PA composite membranes provided a good prospect for further research and development in anti‐bacterial GBR membrane. To cite this article:
Zhang JC, Xu Q, Huang C, Mo AC, Li JD, Zuo Y. Biological properties of an anti‐bacterial membrane for guided bone regeneration: an experimental study in rats.
Clin. Oral Impl. Res. 21 , 2010; 321–327.
doi: 10.1111/j.1600‐0501.2009.01838.x     

Management of peri-implant bone loss using guided bone regeneration: a clinical report

This clinical report presents a patient who developed peri-implant bone loss around 2 maxillary endosseous root-form implants after restoration with cement-retained single crowns. Significant localized bone loss occurred around 1 of the implants due to retained excess cement. Reparative treatment consisted of a guided bone regeneration technique. Following a 9-month period of submerged healing, the implants were re-exposed and restored to complete function.     

Vertical ridge augmentation with guided bone regeneration in association with dental implants: an experimental study in dogs

AIM: To evaluate the effect of using guided bone regeneration (GBR) with a titanium-reinforced e-PTFE membrane in alveolar bone defects with titanium implants. MATERIAL AND METHODS: Following extraction of three mandibular premolars and a molar on both sides of the jaw in three dogs, alveolar bone defects (depth: 5-7 mm) were produced. After 4 months, three implants were inserted into each defect to a depth of approximately 4 mm, so that their coronal portion was protruding about 5 mm. Four sides in the dogs were assigned to a test group and the remaining two sides to a control group. The 12 implants in the test group were covered with a reinforced e-PTFE membrane. The space under the membrane was filled with peripheral venous blood from the animal, and the flaps were sutured over the membrane. The six control implants received no membrane before the suturing of the flaps to complete wound closure. The animals were sacrificed after 6 months, and non-decalcified histological specimens of the implants and surrounding tissues were prepared. RESULTS: Histologic and histomorphometric analyses revealed a significantly (Mann-Whitney test; P=0.08) larger amount of bone fill in the test group (mean=57.42%) than in the controls (mean=11.65%), and clinical evaluation of one test site showed that the implants were completely covered with tissue resembling bone. In most of the specimens, bone had grown in height close to, or in direct contact with the membrane. However, the new bone generally was not in direct contact with the implants. Regularly, a zone of dense connective tissue was interposed between the implants and the newly formed bone. CONCLUSION: The formation of even considerable amounts of bone following vertical ridge augmentation with GBR and implants was not accompanied by predictable osseointegration of the implants.     

Alveolar bone preservation following tooth extraction: a perspective of clinical trials utilizing osseous grafting and guided bone regeneration

Based on data from the authors' three clinical trials that focused on the role exerted by various regenerative materials and techniques in preserving alveolar ridge dimensions following tooth extraction, there is evidence to support the use of nonresorbable and resorbable membranes in combination with a closed-socket approach. There also is evidence to support a higher predictability of the results with resorbable membranes compared with nonresorbable membranes because the latter can become exposed to the oral environment during healing. A combination of bioactive glass and calcium sulfate using an open-socket approach is of marginal benefit in preserving alveolar ridge dimensions following tooth extraction. More research is necessary on combining osseous graft/guided bone regeneration using a closed-socket approach, on assessing the quality of bone present in the previous extraction socket following various preservation techniques, and on how effectively preserved/regenerated bone supports dental implants.     

Evaluation of a new tricalcium phosphate for guided bone regeneration: an experimental study in the beagle dog

Odontology - This study compared the in vivo behavior of two biomaterials, xenograft (Bio-Oss®) and alloplastic tricalcium phosphate (Sil-Oss®), vs a control (no biomaterial) in beagle...     

Histomorphometric evaluation of guided bone regeneration around implants with SLA surface: an experimental study in beagle dogs

The aim of this study was to evaluate the efficacy of collagen membranes, either alone or combined with a human demineralized freeze-dried bone allograft (DFDBA) or natural bovine bone graft, in bone defects around dental implants with an SLA (sand-blasted, large grit, acid-etched) surface. The experiments were carried out in three beagle dogs using a split-mouth design. On one side of the jaw, three implants were placed and intra-bony defects were created and covered with a collagen membrane, randomly combined in two of the defects with human DFDBA or inorganic bovine bone graft. A control implant, without membrane covering or defect filling, was also placed. On the other side of the jaw, three implants were placed and the bone defects were treated in a similar fashion, but without membrane covering. The studied variables were the percentage of bone-to-implant contact within the limits of the initial bony defect and percentage of the original bony defect occupied by bone tissue. Although no statistically significant differences were found in this study between the membrane and nonmembrane groups, bone defects augmented with anorganic bovine bone and membranes showed the most promising results from a histological and histomorphometric perspective.