Calcium alginate film used for guided bone regeneration in mandible defects in a rabbit model

The objective of this research was to study a new bioabsorbable membrane material, calcium alginate film (CAF), used for guided tissue regeneration (GTR) or guided bone regeneration (GBRL). Circular bone defects of five mm diameter were created in the corners of the mandibles in 45 rabbits. The defects covered with calcium alginate film (CAF) served as the experimental sites, and collagen membrane (CM) or no membrane served as the control sites without considering left or right side, just with a mark on the ear of the same side. The healing condition was analyzed by histological studies and histometry analysis after one, two, four, six, and eight weeks. The histological evaluation showed that the bone regeneration pattern was centripetal in growth from the defect rim. The quantitative histometry analysis showed significantly more and faster newly generated bone in CAF defects than that in CM defects or in empty defects (p < 0.01) at two, four, six, and eight weeks postsurgically. Calcium alginate film was more effective for GTR and GBR than the collagen membrane.     

Effect of two different bioabsorbable collagen membranes on guided bone regeneration: a comparative histomorphometric study in the dog mandible

BACKGROUND: This study compared bone regeneration following guided bone regeneration with two bioabsorbable collagen membranes in saddle-type bone defects in dog mandibles. METHODS: Three standardized defects were created, filled with bone chips and deproteinized bovine bone mineral (DBBM), and covered by three different methods: control = no membrane; test 1 = collagen membrane; and test 2 = cross-linked collagen membrane (CCM). Each side of the mandible was allocated to one of two healing periods (8 or 16 weeks). The histomorphometric analysis assessed the percentage of bone, soft tissue, and DBBM in the regenerate; the absolute area in square millimeters of the bone regenerate; and the distance in millimeters from the bottom of the defect to the highest point of the regenerate. RESULTS: In the 8-week healing group, two dehiscences occurred with CCM. After 8 weeks, all treatment modalities showed no significant differences in the percentage of bone regenerate. After 16 weeks, the percentage of bone had increased for all treatment modalities without significant differences. For all groups, the defect fill height increased between weeks 8 and 16. The CCM group showed a statistically significant (P = 0.0202) increase over time and the highest value of all treatment modalities after 16 weeks of healing, CONCLUSIONS: The CCM showed a limited beneficial effect on bone regeneration in membrane-protected defects in dog mandibles when healing was uneventful. The observed premature membrane exposures resulted in severely compromised amounts of bone regenerate. This increased complication rate with CCM requires a more detailed preclinical and clinical examination before any clinical recommendations can be made.     

海藻酸钙膜引导下颌骨缺损再生机理的实验研究

目的:实验已经研究了海藻酸钙膜应用于骨缺损再生的有效性和优越性,作者进一步探讨其引导骨再生的机制。方法:以家兔为研究对象,在其双侧下颌骨形成洞形骨缺损,实验侧骨缺损上覆盖海藻酸钙膜,对照侧未覆盖任何膜,分别在术后1、2、4、6、8周时取出下颌骨,进行大体观察、X线观察、组织学光镜观察、电镜观察以及TGF-β、VEGF免疫组化染色。结果:海藻酸钙膜4～6周吸收;实验侧术后18天X线观察可见骨密度接近正常皮质骨,对照侧4周才达到;前者大体观骨缺损愈合表面平整,后者表面不连续;实验侧术后2周光镜下可见骨小梁构成编织骨,对照侧4周方可见;电镜下术后6周实验侧骨痂致密,对照侧骨痂疏松。TGF-β、VEGF免疫组化表达则有其成骨作用的时空性。结论:海藻酸钙膜通过对骨诱导因子的早期调控引导骨再生,更快地促进骨缺损的愈合,且4～6周降解不影响骨再生修复。     

Bone apposition around two different sandblasted, large-grit and acid-etched implant surfaces at sites with coronal circumferential defects: an experimental study in dogs

Objective: The study was designed to evaluate bone apposition around SLA (sandblasted, large-grit and acid-etched) implants compared with modified SLA (modSLA) ones at sites with different sizes of circumferential gaps.
Material and methods: All mandibular premolars and first molars of six beagle dogs were extracted. After a healing period of 3 months, three 10-mm-long implants were inserted in each side of the mandible. One implant was inserted with a 0.5-mm and one with a 1-mm gap between the implants and bone around the coronal 5 mm of the implants. The third implant was inserted without a gap as a control. The dogs were sacrificed respectively at weeks 2, 4 and 8 after implant placement for histological and histomorphometric analyses.
Results: The histomorphometric results showed similar pattern of bone apposition for the two surfaces. At 2 and 4 weeks of healing, the percentage of newly formed bone-to-implant contact (BIC%), new bone fill (NBF%) and the distance between the most coronal position of BIC and the defect bottom (B–D) were significantly higher for modSLA ( P <0.05). At 8 weeks of healing, this difference was not significant ( P >0.05). With regard to the defect size, the histological analyses showed no significant differences between the two defect sizes at all time points ( P >0.05).
Conclusion: Significantly more bone apposition was found for the modSLA surface than for the SLA surface at early stage of healing, indicating that modSLA surface may enhance bone apposition in coronal circumferential defects at non-submerged implants. Gap size within 1 mm may not need any kind of regenerative procedures.     

A randomized, controlled clinical trial to evaluate a new membrane for guided bone regeneration around dental implants

Objectives: The use of barrier membranes in guided bone regeneration (GBR) procedures for the treatment of alveolar bone defects is common practice. The objective of this study was to test whether a synthetic bioresorbable polyethylene glycol (PEG) hydrogel membrane could result in a similar amount of vertical bone fill as a standard collagen membrane, both combined with a membrane supporting material.
Material and methods: The study enrolled 37 patients requiring implant treatment with an expected osseous defect in the posterior maxilla or mandible. After raising a mucoperiosteal flap, the implant sites were prepared and dental implants placed. The defect height was then measured and defects <3 mm were excluded from the study. Defects were grafted with bovine bone mineral and randomly covered with either a collagen membrane (control group, 18 patients) or a PEG hydrogel membrane (test group, 19 patients), which is applied as a liquid. After a healing period of 6 months, surgical re-entry was performed and the change in vertical bone height from baseline evaluated.
Results: Well-vascularized hard tissue was apparent at all sites and the regenerated bone was similar to the surrounding native bone. Mean vertical defect fill after 6 months was 5.63±1.84 mm at test sites and 4.25±1.16 mm at control sites, and the mean defect fills were 94.9% and 96.4% at test and control sites, respectively. More soft tissue complications were observed with the PEG membrane (e.g., delayed or incomplete wound healing) but all sites recovered uneventfully.
Conclusions: The new PEG hydrogel membrane was as successful as a standard collagen membrane in the treatment of bony dehiscence defects around dental implants with simplified clinical handling.     

Comparison of calcium alginate film with collagen membrane for guided bone regeneration in mandibular defects in rabbits

PURPOSE: We sought to compare calcium alginate film (CAF) with collagen membrane (CM) regarding their effects on guided bone regeneration. MATERIALS AND METHODS: Circular bone defects with 5-mm diameter were created in the region anterior to both mandibular angles in 34 rabbits. The defects on one side were covered with a CAF, and the contralateral side with CM. Healing condition was analyzed with gross, radiographic, electromicroscopic, histologic, and immunohistochemical studies and image pattern analysis system after 1, 2, 4, 6, and 8 weeks. RESULTS: CM absorbed more slowly but collected fewer osteoinductive factors (P <.05) in the early period. CAF induced dense bone formation, whereas CM produced less newly formed bone. CONCLUSION: CAF is more efficacious than CM in guided bone regeneration in this animal model.     

Wound healing following regenerative procedures in furcation degree III defects: histomorphometric outcomes

Degree III furcation involvements were surgically created at four first molars in each of three monkeys. Following 6 weeks of healing, full-thickness flaps were elevated. Following 24% EDTA gel conditioning, the defects were treated with one of the following: (1) enamel matrix proteins (EMD), (2) guided tissue regeneration (GTR) or (3) a combination EMD and GTR. The control defects did not receive any treatment. After 5 months of healing, the animals were sacrificed. Three 8 μm thick histological central sections, 100 μm apart, were used for histomorphometric analysis in six zones of each tooth either within the furcation area or on the pristine external surface of the root. In all specimens, new cementum with inserting collagen fibres was formed. Following GTR or GTR + EMD, cementum was formed up to and including the furcation fornix indicating complete regeneration on the defect periphery. Periodontal ligament fibres were less in all four modalities compared to pristine tissues. In the teeth treated with GTR and GTR + EMD a higher volume of bone and periodontal ligament tissues was observed compared to EMD. After 5 months of healing, regenerated tissues presented quantitative differences from the pristine tissues. In the two modalities where GTR alone or combined with EMD was used, the regenerated tissues differed in quantity from the EMD-treated sites.     

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.     

Effects of the combination with α-tricalcium phosphate and simvastatin on bone regeneration

Background: Although local application of statins stimulates bone formation, high dose of simvastatin induces inflammation.
Objective: A study was conducted to test the hypothesis that maximum bone regeneration with less inflammation would be achieved by combining an optimal dose of simvastatin with α-tricalcium phosphate (α-TCP), which is an osteoconductive biomaterial capable of releasing the drug gradually.
Material and methods: Bilateral 5-mm-diameter calvarial defects were created in adult Wistar rats and filled with preparations of different doses of simvastatin (0, 0.01, 0.1, 0.25 and 0.5 mg) combined with α-TCP particles or left empty. The animals were sacrificed at 2, 4 and 8 weeks and analyzed radiologically and histologically. Half of the animals of 4 and 8 weeks were labeled with fluorescence dyes and histomorphometrically analyzed.
Results: Simvastatin doses of 0.25 and 0.5 mg caused inflammation of the soft tissue at the graft site whereas control and other doses did not. The micro-CT analysis revealed that the α-TCP with 0.1 mg simvastatin (TCP-0.1) group yielded significantly higher bone volumes than untreated control group at all three time points (249%, 227% and 266% at 2, 4 and 8 weeks, respectively). The percentage of defect closure, bone mineral content and bone mineral density were also higher in the TCP-0.1 group than in the other groups.
Conclusion: When combined with α-TCP particles, 0.1 mg simvastatin is the optimal dose for stimulation of the maximum bone regeneration in rat calvarial defects without inducing inflammation and it could be applied as an effective bone graft material.     

海藻酸钙膜引导成骨作用的初步研究

目的 评价海藻酸钙膜在骨缺损应用中的有效性和优越性。方法 以家兔为研究对象,在其双侧下颌角前切迹处形成直径5mm的骨缺损,以覆盖海藻酸钙膜作为实验组,以覆盖胶原膜以及不作处理作为两个对照组。术后1、2、4、6周时取出下颌骨,进行常规组织学观察并进行组织计量学分析,计算成骨面积。结果 在各组内,覆盖海藻酸钙膜的缺损区新生骨面积均明显高于覆盖胶原膜以及空白对照组（P<0.01）。术后4周,覆盖海藻酸钙膜的缺损区已达骨性愈合,而覆盖胶原膜组组织反应明显,空白组纤维结缔组织较多。结论 海藻酸钙膜比胶原膜效果更好,能更快地促进骨缺损的愈合,组织反应过程短、程度轻。     

Open flap debridement and guided tissue regeneration after 10 years in infrabony defects

Objective: Evaluation of the 10-year results after open flap debridement (OFD) and guided tissue regeneration (GTR) therapy of infrabony defects in a randomized controlled clinical trial.
Materials and Methods: In 16 periodontitis patients OFD or polylactide acetyltributyl citrate barriers (GTR; n =23) were assigned randomly to 44 infrabony defects. In a subgroup of 10 patients exhibiting 2 contra-lateral defects each OFD and GTR was assigned to either side (split-mouth). At baseline, 12, and 120 ± 12 months after surgery clinical parameters were obtained.
Results: Fifteen patients (41 defects) were available at 120 months. Twelve and 120 ± 12 months after therapy both groups showed statistically significant ( p <0.01) attachment gain (split-mouth: OFD: 12 months: 3.60 ± 2.67 mm; 120 months: 3.65 ± 3.36 mm; GTR: 12 months: 3.50 ± 1.90 mm; 120 months: 2.85 ± 2.24 mm; parallel: OFD: 12 months: 3.47 ± 2.80 mm; 120 months: 3.41 ± 2.75 mm; GTR: 12 months: 3.67 ± 2.11 mm; 120 months: 2.89 ± 2.12 mm). From 12 to 120 months both groups experienced insignificant attachment changes, however, six teeth (two OFD, four GTR) were lost (all for prosthodontic reasons). The study failed to show statistically significant attachment gain differences between both groups after 120 months.
Conclusions: Ten years after OFD and GTR in infrabony defects 35 of 41 teeth were still in place.     

Periodontal repair in dogs: a bioabsorbable calcium carbonate coral implant enhances space provision for alveolar bone regeneration in conjunction with guided tissue regeneration

BACKGROUND: Collapse or compression of a barrier device into a periodontal defect or onto the root surface compromises outcomes following guided tissue regeneration (GTR). Bone biomaterials have been suggested to support regeneration of alveolar bone and to improve space provision with GTR devices. The objective of this study was to evaluate space provision, alveolar bone, and cementum regeneration following use of a bioabsorbable, calcium carbonate biomaterial in conjunction with GTR. METHODS: Routine, critical size, 5 to 6 mm, supraalveolar, periodontal defects were created in 5 young adult beagle dogs. Alternate jaw quadrants in consecutive animals received GTR and the coral biomaterial (cGTR) or GTR alone. The animals were euthanized 4 weeks postsurgery and tissue blocks processed for histometric analysis. RESULTS: The coral implant particles were surrounded by newly-formed bone or immersed in connective tissue and appeared to resorb and be replaced by bone. There was limited, if any, appreciable cementum regeneration. Space provision was enhanced in cGTR compared to GTR sites (6.1 +/- 1.6 versus 2.4 +/- 0.8 mm2; P<0.05). Bone regeneration (height) was significantly increased in cGTR compared to GTR sites averaging 1.9 +/- 0.6 and 1.2 +/- 0.6 mm, respectively (P<0.05). Bone regeneration (area) was 2-fold greater in cGTR sites compared to the GTR control (3.3 +/- 1.8 versus 1.4 +/- 0.5 mm2), however the difference was not statistically significant (P>0.05). CONCLUSIONS: The coral implant significantly enhanced space provision for GTR while alveolar bone formation appeared to be enhanced by its use. Increased healing intervals are needed to fully understand the biologic value of the coral implant as an adjunct to GTR.     

Guided bone regeneration using rhGDF-5- and rhBMP-2-coated natural bone mineral in rat calvarial defects

Objectives: The aim of the present study was to assess the influence of either recombinant human growth and differentiation factor 5 (rhGDF-5)- or recombinant human bone morphogenetic protein 2 (rhBMP-2)-coated natural bone mineral (NBM) on guided bone regeneration in a rat calvarial defect model.
Material and methods: Two monocortical critical-size calvarial defects (diameter 6 mm, depth 1.5 mm) were prepared in a total of 90 rats each ( n =180 defects) and randomly allocated to the following groups: (1) NBM+collagen membrane (BG), (2) rhBMP-2+NBM+BG, (3) rhGDF-5+NBM+BG, (4) autogenous bone (AB)+BG, or (5) untreated control (C). At 1, 2, 4, 8, 16, and 24 weeks, dissected blocks were processed for histological [e.g. area (mm²) of mineralized tissue (MT)] and immunohistochemical (osteocalcin – OC, angiogenesis – TG) analysis.
Results: At 2 weeks, both coated NBM groups exhibited the formation of a thin hard tissue bridge underneath the BG. All test groups revealed significantly higher mean MT values than the C group at 24 weeks. rhBMP-2+NBM+BG-treated defects revealed significantly higher mean MT values in comparison with the AB+BG (8 and 24 weeks), NBM+BG (2 and 4 weeks), and rhGDF-5+NBM+BG (2, 16, and 24 weeks) groups, respectively. Immunoreactions to either OC or TG were comparable in all test groups.
Conclusion: It was concluded that (i) all treatment procedures investigated supported bone regeneration at 24 weeks and (ii) rhBMP-2 might have the potential to improve the outcome of healing, particularly during the early stages of healing.     

Acellular dermal matrix as a barrier in guided bone regeneration: a clinical, radiographic and histomorphometric study in dogs

Objectives: The purpose of this study was to evaluate the effectiveness of the acellular dermal matrix (ADM) as a membrane for guided bone regeneration (GBR), in comparison with a bioabsorbable membrane.
Material and methods: In seven dogs, the mandibular pre-molars were extracted. After 8 weeks, one bone defect was surgically created bilaterally and the GBR was performed. Each side was randomly assigned to the control group (CG: bioabsorbable membrane made of glycolide and lactide copolymer) or the test group (TG: ADM as a membrane). Immediately following GBR, standardized digital X-ray radiographs were taken, and were repeated at 8 and 16 weeks post-operatively. Before the GBR and euthanasia, clinical measurements of the width and thickness of the keratinized tissue (WKT and TKT, respectively) were performed. One animal was excluded from the study due to complications in the TG during wound healing; therefore, six dogs remained in the sample. The dogs were sacrificed 16 weeks following GBR, and a histomorphometric analysis was performed. Area measurements of new tissue and new bone, and linear measurements of bone height were performed.
Results: Post-operative healing of the CG was uneventful. In the TG membrane was exposed in two animals, and one of them was excluded from the sample. There were no statistically significant differences between the groups for any histomorphometric measurement. Clinically, both groups showed an increase in the TKT and a reduction in the WKT. Radiographically, an image suggestive of new bone formation could be observed in both groups at 8 and 16 weeks following GBR.
Conclusion: ADM acted as a barrier in GBR, with clinical, radiographic and histomorphometric results similar to those obtained with the bioabsorbable membrane.     

骨形态蛋白复合物联合引导组织再生技术修复牙周骨缺损的实验研究

目的评价骨形态蛋白复合物联合引导组织再生技术修复牙周骨缺损的效果。方法选择6只新西兰兔，制备下前牙牙周骨缺损模型，将其分为3组：GTR组(牙周骨缺损处植入胶原膜)、BMP组(牙周骨缺损处植入骨形态蛋白复合物和胶原膜)和OFD组(牙周骨缺损处未植入任何物，对照组)。术后12周分别观察各组缺损处的组织学变化。结果BMP组骨缺损处只见少量的软组织，新生骨组织的量及其成熟程度明显优于GTR组和OFD组，显示骨组织修复良好。结论骨形态蛋白复合物联合GTR技术修复牙周骨缺损，与传统的GTR术和牙周翻瓣术相比，更能有效促进牙周骨组织再生与修复。     

浓缩生长因子联合微创外科技术治疗牙周炎垂直骨缺损的效果评价

目的    评价浓缩生长因子（concentrated growth factors,CGF）联合微创外科技术（minimally invasive surgical technique,MIST）治疗牙周炎垂直骨缺损的临床效果。方法    选取2020年9月至2021年7月于合肥市口腔医院牙周科就诊的牙周炎垂直骨缺损患者39例,随机分为3组,每组各13例,分别采用牙周引导组织再生术（guided tissue regeneration,GTR）（GTR组）、GTR联合CGF（GTR+CGF组）、MIST（头戴式放大镜+保留龈乳头切口+细针细线改良褥式缝合）联合CGF（MIST+CGF组）进行治疗。比较3组患者术前、术后6个月垂直骨缺损位点的探诊深度（probing depth,PD）、出血指数（bleeding index,BI）、临床附着丧失（clinical attachment loss,CAL）、牙槽骨缺损深度和牙龈退缩深度。结果    3组术前各项测量指标比较,差异均无统计学意义（均P > 0.05）;术后6个月,3组PD、BI、CAL和牙槽骨缺损深度相较于术前均有明显改善,但也均发生了牙龈退缩,差异均有统计学意义（均P < 0.05）;术后6个月,3组各项测量指标比较,差异均无统计学意义（均P > 0.05）。结论    CGF联合MIST治疗牙周炎垂直骨缺损与传统治疗方法一样具有良好的临床效果,其优势有待进一步研究。     

Comparative histologic analysis of coronally advanced flap with and without collagen membrane for root coverage

BACKGROUND: Guided tissue regeneration (GTR)-based root coverage has been utilized to correct gingival recession defects with promising results. However, limited histologic information is available. Therefore, the aims of this study were to clinically and histologically evaluate the efficacy of GTR-based root coverage using collagen membrane (GTRC) and to compare the healing response to that of coronally advanced flaps (CAF). METHODS: Standardized gingival recession defects were surgically created on the labial surfaces of the maxillary cuspids of 8 mongrel dogs. Plaque was allowed to accumulate for 8 weeks to develop a plaque-infected recession defect. Full-mouth scaling and root planing was then performed coincident with 4 weeks of oral hygiene. Defects were randomly assigned to receive either GTRC or CAF surgery. Four dogs each were sacrificed at 4 and 16 weeks post-treatment. Clinical measurements included: percent root coverage, the amount of keratinized gingiva (KG), and probing depth (PD). Sulcular depth, junctional epithelium and connective tissue attachment, new cementum formation, and new bone formation were evaluated histomorphometrically. RESULTS: Clinically, both treatments (CAF and GTRC) achieved statistically significant (P <0.05) root coverage compared to baseline. KG was significantly increased in CAF-treated sites at 16 weeks, while no significant differences were found for other clinical parameters between treatments. Histometrically, GTRC showed a statistically significant increase of new attachment and newly formed connective tissue when compared to CAF at 16 weeks. CONCLUSION: Within the limits of this preclinical study, both GTRC and CAF can be successfully used for the treatment of gingival recession defects.     

Evaluation of the regenerative effect of a 25% doxycycline-loaded biodegradable membrane for guided tissue regeneration

BACKGROUND: Biodegradable materials have been successfully utilized for guided tissue regeneration (GTR) and local delivery systems (LDS) because they are biocompatible, less cytotoxic, and do not require removal. Several studies have demonstrated that tetracyclines (TCs), when applied topically, stimulated osteogenesis in experimental bone defects. The purpose of this study was to evaluate the regenerative effect of a 25% doxycycline-loaded biodegradable GTR membrane (Doxy-M) in dogs. METHODS: Doxy-M was made by coating the inner surface of a biodegradable membrane (BD-M) with 25% doxycycline. Five male mongrel dogs with 20 created osseous defects were enrolled. The plain BD-M was used as the control membrane. Either Doxy-M or BD-M was applied in 20 randomly selected defects (10 Doxy-M, 10 BD-M) for 12 weeks with the GTR technique. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJP), new cementum height (NCH), new bone height (NBH), and new bone area (NBA). RESULTS: The Doxy-M-treated defects showed more pronounced new bone formation and less crestal bone resorption than the BD-M-treated defects. There were no statistically significant differences between the two groups in DH, AEJP, and NCH. Statistically significantly larger NBH (P <0.05) and NBA (P<0.005) were seen in the Doxy-M-treated defects. CONCLUSIONS: The results strongly suggest that Doxy-M may have a beneficial effect on osteogenesis to favor periodontal regeneration.     

Prognostic factors for alveolar regeneration: osteogenic potential of resident bone

OBJECTIVES: There is a limited understanding of the role of resident bone in periodontal regeneration. The objective of this study was to evaluate the influence of the resident alveolar bone on bone regeneration in conjunction with guided tissue regeneration (GTR) in the presence or the absence of cell occlusivity. METHODS: Critical-size, 6-mm, supra-alveolar periodontal defects were created in six young adult Beagle dogs. Space-providing, occlusive or porous expanded polytetrafluaroethylene devices 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 postsurgery. The histometric analysis assessed regeneration of alveolar bone relative to space-provision by the GTR device and width of the alveolar crest at the base of the defect. RESULTS: There were no significant differences in mean alveolar regeneration between sites receiving the porous GTR device with a narrow versus a wide alveolar ridge after adjusting for wound area (2.22 versus 2.50 mm, respectively; p=0.36). In contrast, analysis using sites receiving the occlusive GTR device revealed significantly greater bone regeneration at sites with a wide compared with a narrow alveolar ridge (3.34 versus 2.53 mm, respectively; p=0.02). Regression analysis showed a significant relationship (p< or =0.05) between space-provision and bone regeneration for all groups except for sites with a wide alveolar ridge receiving the occlusive GTR device (p=0.5). CONCLUSIONS: The resident alveolar bone may significantly influence the magnitude of alveolar bone regeneration. The relative presence of cells from the gingival connective tissue may attenuate this effect.