Regeneration of bone graft donor sites

When crestal volume is greatly insufficient for the placement of dental implants, bone grafting is usually the most reliable ridge augmentation procedure. The grafts are most often taken in parietal or mandibular symphysis regions. Though not too noticeable, it seems contra-indicated and even potentially dangerous to leave zones like the cranium to repair spontaneously. Guided bone regeneration techniques have shown their ability to regenerate new bone under difficult conditions in jaws. Their use in bone graft donor sites is simple and the results are consistent. This report shows that 2 types of resorbable membranes are equally as efficacious in terms of new-bone formation.     

Clinical outcome of autogenous bone blocks or guided bone regeneration with e‐PTFE membranes for the reconstruction of narrow edentulous ridges

The aim of this study was to analyse the clinical outcome of two different surgical methods for the reconstruction of narrow edentulous ridges before implant installation: guided bone regeneration with e-PTFE membranes and autologous bone chips or grafting of autologous bone blocks without e-PTFE membranes. Thirty partially edentulous patients, presenting insufficient bone width (less than 4 mm) in the edentulous sites for installation of screw-type titanium implants, were selected and assigned to two different treatment modalities. Fifteen patients (group 1) were treated by means of guided bone regeneration with e-PTFE membranes supported by stainless steel screws and autologous bone chips taken from intraoral sites. Fifteen patients (group 2) were treated by means of autologous bone blocks taken from intraoral or extraoral sites (anterior iliac crest and calvaria) and stabilized with titanium microscrews. Six to 8 months later, during re-entry for implant insertion, the gain of ridge width obtained was measured. In group 1 the average amount of bone gain was 2.7 mm, whereas in group 2 the value was 4.0 mm. Five to 6 months after implant placement prosthetic rehabilitation was started. The mean follow-up after prosthetic load has been 22.4 months. Success rates of implants according to Albrektsson criteria has been 93.3% in group 1, and 90.9% in group 2. Although a statistical comparison between the two treatment modalities may not be feasible, due to the bias resulting from the choice of treatment by the clinician and from the differences in donor sites and defect extension, some considerations can be made: 1) both methods are a reliable means for the correction of narrow edentulous ridges; 2) both techniques necessitate overcorrection of the defect because of interposition of connective tissue beneath the membrane in the first group and bone resorption in the second one; 3) the use of semipermeable barriers increases the costs of the surgical procedure, as compared to bone grafting without membranes; 4) guided bone regeneration presents a higher risk of infection because of wound dehiscence and membrane exposure. Therefore, in case of wide edentulous areas, reconstruction of narrow ridges should be performed with bone blocks without membranes.     

Treatment of severe peri‐implant bone loss using autogenous bone and a resorbable membrane. Case report and literature review.

Clinical case reports and animal studies have demonstrated that the principle of guided bone regeneration can be applied for surgical treatment of moderate to profound peri‐implant bone loss (peri‐implantitis). However, the degree of bone regeneration within the peri‐implant osseous defect was reported to be variable depending on different clinical factors and on the postoperative course. Most papers dealing with surgical treatment of peri‐implantitis advocate the use of a non‐resorbable ePTFE membrane for secluding the peri‐implant bone defect enabling bone regeneration. Additionally some surgeons fill the defects with allografts or alloplasts. The present case report demonstrates another surgical approach by using autogenous cancellous bone for grafting into the peri‐implant bone defect and placing a bioresorbable polylactide membrane as a matrix barrier. The successful out‐come of this modified surgical approach enabled the patient to maintain the implant for prosthetic reconstruction after early but severe bone loss.     

Histological morphology of the e‐FTFE/tissue interface in humans subjected to guided bone regeneration in conjunction with oral implant treatment

The purpose of the present investigation was to study the histological morphology of the e‐PTFE membrane/tissue interface in 5 humans subjected to GBR treatment in conjunction with oral implant treatment. Oral implants (Bråemark System®) were inserted in extraction sockets 1 to 2 months after extraction of periodontally diseased teeth. The implants were placed approximately 2 mm below the surrounding bone margins. Specially designed 3 mm high cover‐screws with horizontal slits for tissue ingrowth were applied to the implants and covered with e‐FIFE membranes (GoreTex Augmentation Material). Reentry was made 7 months later, except in 1 case where the membrane was removed 1 month postoperatively due to exposure and infection. In the remaining 4 sites, circular biopsies comprising membranes, tissues and cover‐screws were retrieved. The specimens were fixated, processed and sectioned for light‐ and transmission electron microscopy. The space between the membrane and the cover‐screw was occupied by fibrous tissue and varying amounts of bone. A cell‐ and vessel‐rich fibrous tissue separated the bone from the membrane in the majority of the specimens. The membrane itself was penetrated by fibrous tissue. Fibroblasts and macrophages were the main cell types found in the fibrous issue. The presence of irregularly shaped cells and unevenly distributed collagen fibres, indicated that the absence of bone formation may be due either to micromovements in the e‐PTFE/tissue interface or to formation of fibrous tissue underneath the membrane by penetrating fibroblasts or a combination of these 2 phenomena.     

Guided bone regeneration around endosseous implants using a resorbable membrane vs a PTFE membrane

The aim of the present experimental pilot study was to assess bone regeneration underneath resorbable barrier membranes vs non-resorbable extended polytetrafluoroethylene (ePTFE) membranes in peri-implant defects. Two implants were inserted into surgically created defects on each side of the mandibles of 6 adult beagle dogs 3 months after extraction of all premolar teeth. One implant on each side was covered with a porous polylactic acid membrane or a ePTFE membrane, respectively, while the second implant served as control. Fluorochrome labelling was administered during the 1st, 5th, 12th and the 18th week. Three animals each were evaluated after 3 and 6 months. Bone regeneration was assessed by measuring the distance from the first fluorochrome label to the level of the regenerated bone immediately adjacent to the implant surface and to the top of the newly formed alveolar contour both on the lingual and buccal side. The increase in bone height was significantly higher compared to the controls under both barrier membranes after 3 months at the top of the alveolar crest but not immediately adjacent to the implant surface. After 6 months, bone height was significantly increased only at the top of the alveolar contour underneath the ePTFE membranes, while bone underneath the polylactic acid membranes showed signs of superficial resorption. It is concluded that guided bone regeneration underneath barrier membranes can restore alveolar bone contour but is not necessarily associated with a higher bone/implant contact. The use of resorbable membranes may be associated with untoward biological effects at later stages, when membrane degradation starts due to degradation products of the polymer material or decreasing membrane stability. Future efforts have to refine the relation between degradation kinetics, membrane porosity and mechanical properties of degradable barrier membranes to improve membrane performance.     

Localized edentulous ridge augmentation with upside down osteotomy prior to implant placement

Abstract –  Localized bone defects may be seen following the extraction of teeth with periapical lesion or advanced periodontal disease, or as a result of trauma. When these regions are considered for treatment with implants, localized ridge augmentation will be necessary. Autogenous bone grafts are used exclusively for ridge augmentation. This case report represents the treatment of a localized edentulous ridge with an upside down osteotomy technique at the symphysis region prior to implant placement. Systemically healthy 21-year-old female patient, who was missing a lower right incisor tooth, was scheduled for an implant treatment. However, the crestal width was only 1 mm. The augmentation was planned and the region was treated with an upside down osteotomy technique. Nine months after the augmentation procedure, the computed tomography (CT) examination of the area revealed that the width of the crest was 7 mm, and the height of the crest was in good relation with the cementoenamel junction of the adjacent teeth. Flipping a bone block graft, which was harvested from the edentulous area, upside down may provide a successful result in partially edentulous ridges, in both maxilla and mandible.     

A systematic review of the survival of implants in bone sites augmented with barrier membranes (guided bone regeneration) in partially edentulous patients

The aim of the present systematic review was to assess the survival of implants in regenerated bone applying the method of guided bone regeneration (GBR) compared with the survival of implants in non-regenerated bone. Studies to be included in this review needed to provide at least 12-month results following prosthetic reconstruction of titanium implants in bone regenerated by GBR with or without membrane supporting materials. The outcome measures were implant survival described as presence of implant, implant success (according to the criteria in the respective study), absence of clinical implant mobility, absence of implant fracture, absence of progressive peri-implant crestal bone loss as assessed on radiographs without clinical signs of peri-implant infection, absence of peri-implant infection with suppuration. A MEDLINE search and a hand search of relevant scientific journals were conducted including studies from the year 1990 to May 2001. A total of 11 studies could be identified fulfilling the inclusion criteria. All studies except two had the characteristics of case series or cross-sectional surveys. The two different studies had both test and control implants included in their analysis and qualified as controlled clinical trials. Cumulative success or survival rates, respectively, for implants in regenerated bone ranged from 100% after 5 years to 79.4% after 5 years of function. Regarding survival data, no significant differences were found in the controlled clinical trials between implants in regenerated compared to implants in non-regenerated bone. Within the limits of this systematic review characterized by second and third levels of evidence, the following conclusions can be drawn: The survival rate of implants placed into sites with regenerated/augmented bone using barrier membranes varied between 79% and 100% with the majority of studies indicating more than 90% after at least one year of function. The survival rates obtained in the present systematic review are similar to those generally reported for implants placed conventionally into sites without the need for bone augmentation.     

Long‐term stability of osseointegrated implants in bone regenerted with the membrane technique. 5‐year results of a prospective study with 12 implants.

The purpose of the present clinical study was to evalutate the 5‐year results of the first 12 implants inserted at the University of Berne in regenerated bone following successful ridge augmentation with the membrane technique. The patients were recalled and examined with clinical and radiographic paramenters routinely utilized in prospective studies with standard implants in non‐regenerated bone. Based on clinical and radiographic findings, all 12 implants were considered successfully integrated according to strict criteria of success. The detailed analysis of clinical parameters revealed no differences to results of prospective studies on standard implants in non‐regenerated bone. All implants demonstrated ankylotic stability which was confirmed by a mean Periotest value of ‐2.08. The radiographic analysis showed stable bone crest levels with a mean bone loss between the 1‐ and 5‐year examination of 0.30 mm. However, 2 implants exhibited a bone loss of more than 1 mm between the 1‐ and 5‐year examination. Therefore, the prognosis of these 2 implants seems questionable at the present time. It can be concluded that bone regenerated with the membrane technique reacts to implant placement like non-regenerated bone, since all 12 implants achieved successful tissue integration with functional ankylosis. Furthermore, this bone is also load‐bearing, since all 12 implants maintained osseointegration over a 5‐year period.     

Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine‐derived xenograft: a randomized,controlled clinical trial

Objectives: The aim of this randomized, controlled clinical trial was to compare the potential of a synthetic bone substitute or a bovine‐derived xenograft combined with a collagen membrane to preserve the alveolar ridge dimensions following tooth extraction. Methods: Twenty‐seven patients were randomized into two treatment groups following single tooth extraction in the incisor, canine and premolar area. In the test group, the alveolar socket was grafted with Straumann Bone Ceramic^® (SBC), while in the control group, Bio‐Oss^® deproteinized bovine bone mineral (DBBM) was applied. In both groups, a collagen barrier was used to cover the grafting material. Complete soft tissue coverage of the barriers was not achieved. After 8 months, during re‐entry procedures and before implant placement, the horizontal and vertical dimensions of the residual ridge were re‐evaluated and trephine biopsies were performed for histological analysis in all patients. Results: Twenty‐six patients completed the study. The bucco‐lingual dimension of the alveolar ridge decreased by 1.1±1 mm in the SBC group and by 2.1±1 in the DBBM group (P<0.05). Both materials preserved the mesio‐distal bone height of the ridge. No differences in the width of buccal and palatal bone plate were observed between the two groups. The histological analysis showed new bone formation in the apical part of the biopsies, which, in some instances, was in direct contact with both SBC and DBBM particles. The coronal part of the biopsies was occupied by a dense fibrous connective tissue surrounding the SBC and DBBM particles. Conclusion: Both biomaterials partially preserved the width and the interproximal bone height of the alveolar ridge. To cite this article:
Mardas N, Chadha V, Donos N. Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine‐derived xenograft: a randomized, controlled clinical trial.
Clin. Oral Impl. Res. 21 , 2010; 688–698.     

Alveolar bone formation at dental implant dehiscence defects following guided bone regeneration and xenogeneic freeze‐dried demineralized bone matrix

The present study evaluated rate and extent of alveolar bone formation in dental implant dehiscence defects following guided bone regeneration(GBR) and implantation of xenogeneic freeze‐dried demineralized bone matrix (xDBM). A total of 16 titanium plasma‐sprayed (TPS) and 16 hydroxyapatite‐coated (HA) titanium cylinder implants were inserted in 4 mongrel dogs following extraction of the mandibular premolar teeth. Four implant sites per jaw quadrant (2 TPS and 2 HA implant sites) were prepared into extraction sockets in each dog. Buccal alveolar bone was removed to create 3 x 5 mm dehiscence defects. Two jaw quadrants in separate animals received GBR, GBR+xDBM, xDBM (control), or gingival flap surgery alone (GFS; control). Thus, four conditions were available for each implant type (TPS or HA): GBR, GBR+xDBM; xDBM and GFS. The animals received fluorescent bone labels to allow observations of rate and extent of bone formation. Animals were sacrificed at 12 weeks postsurgery and block sections were harvested for histologic analysis. There were no apparent histologic differences between TPS and HA implant defects. GBR and GBR+xDBM resulted in almost complete bone closure of the dental implant dehiscence defect. Rate of bone formation appeared higher following GBR alone. Extent of bone formation appeared somewhat greater following GBR+xDBM; however, delayed. xDBM alone did not adequately resolve the bony defect. In conclusion, GBR results in rapid, clinically relevant bone closure of dental implant dehiscence defects. Adjunctive implantation of xDBM does not appear to significantly improve the healing response in the model used.     

Guided tissue regeneration procedure with bioresorbable membranes versus conventional flap surgery in the treatment of infrabony periodontal defects

AIM: Claims are being made that clinical results of periodontal flap surgery are enhanced when membranes are employed to aid GTR in intrabony pockets. It was the aim of our study to determine whether this assumption was true for a certain bioresorbable membrane (Guidor Matrix Barrier). METHOD: 44 intrabony defects were treated in 16 patients. In 21 lesions, conventional flap surgery only was performed, while in 23, similar lesion membranes were placed as an additional treatment task. Results were evaluated over a time span of 12 months. RESULTS: In all surgical areas, treatment resulted in significant improvement of parameters such as attachment levels and probing depths, as well as index values for plaque and bleeding on probing. This occurred whether membranes had been used or not, without any significant differences when comparing the collective results of both treatment groups. CONCLUSIONS: Placement of membranes during periodontal surgery for the enhancement of tissue regeneration in intrabony pockets is often both difficult and time consuming. In the light of our clinical results with resorbable membranes, such extra effort seems hardly warranted.     

Interest in periodontology and preferences for treatment of localized gingival recessions

OBJECTIVES: The purpose of this study was to evaluate the views, knowledge and preferences of a large sample of practising dentists in periodontics, focusing specifically on the treatment of gingival recessions, and to compare the findings with the current evidence available in the dental literature. METHODS: We conducted a cross-sectional postal survey of 3780 dentists, representing the majority of all dentists working in Switzerland. The questionnaire consisted of 17 questions, most of them giving the possibility of multiple choices of answers. The demographic profile, interests and satisfaction in periodontics were associated with the choice of treatment options offered for the management of six clinical situations. RESULTS: One thousand two hundred and one dentists sent back the questionnaire within three months and were thus included in the analysis. In general, the interest and the satisfaction in periodontics were moderate to high (6-7 on an analogue scale from 1 to 10). Specialists in periodontics indicated a significantly higher interest and satisfaction in periodontics than the general dentists (p<0.001), and practitioners working in urban areas indicated a slightly higher interest (p=0.027) and satisfaction (0.047) than their colleagues established in a rural setting. The predominant indication of root coverage procedures was aesthetics (90.7%). The region in which dentists worked was the only significant predictor for choosing "no treatment" of buccal recessions: dentists from the German-speaking part were significantly less inclined to surgically treat gingival recessions than their colleagues from the French or Italian part. For those who opted for therapy, a free tissue graft was generally the favourite option, followed by a connective tissue graft and a coronally advanced flap. Throughout, only a small fraction of the dentists considered using a guided tissue regeneration procedure. The relative odds for not extracting teeth with severe periodontal disease were higher if the dentist was a specialist than a generalist. Satisfaction in practicing periodontics also positively strengthened the inclination towards keeping severely compromised teeth. CONCLUSIONS: Aesthetic concerns were the predominant indication for root coverage procedures. Further research should therefore include aesthetic aspects as primary clinical outcome variables. Specific training of dentists and their satisfaction in periodontics influenced treatment decisions. Specialists involved in continuing education should inform practicing dentists more efficiently on the potential and usefulness of periodontal therapy for saving and maintaining periodontally compromised teeth.     

Bone morphogenetic protein‐2 for peri‐implant bone regeneration and osseointegration

Recombinant human bone morphogenetic protein‐2 (rhBMP‐2) induced bone regeneration and osseointegration was evaluated in supra‐alveolar peri‐implant defects in 5 beagle dogs. Alveolar bone was reduced 5 mm in height in mandibular premolar areas and the premolars were extracted. Three 10 mm titanium fixtures were placed 5 mm into each reduced alveolar crest, leaving 5 mm in a supraalveolar position. Alternate quadrants in consecutive animals received a surgical implant consisting of 2 ml rhBMP‐2 (0.43 mg/ml) in a type I bovine collagen carrier, or the carrier alone (control). Fixtures and surgical implants were submerged under the gingival flaps. The healing interval was 16 weeks. Histometric and radiographic evaluations were made. Defect height averaged (*SD) 5.3±O.2 and 5.1±0.2 mm for rhBMP‐2 and control defects, respectively ( P >0.05, n =5, paired, f‐test) Bone regeneration (height) averaged 4.2+1.0 and 0.5±0.3 mm for rhBMP‐2 and control defects, respectively ( P >0.05). Bone regeneration (area) averaged 6.1±6.3 and 0.2±0.2 mm² for rhBMP‐2 and control defects, respectively ( P ±0.05). Osseointegration within the confines of the defect averaged 19.1±10.1% and 8.2±4.6% for rhBMP‐2 and control defects, respectively ( P 0.05). The results suggest that there is a potential for rhBMP‐2 induced bone regeneration and osseointegration in surgical peri‐implant defects.     

Mandibular bone harvesting for alveolar reconstruction and implant placement: subjective and objective cross-sectional evaluation of donor and recipient site up to 4 years

Aim: To evaluate the long‐term morbidity of intraoral bone harvesting from two different donor sites (mandibular symphysis or ramus) for bone augmentation procedures before or at the time of implant placement and to evaluate the success and the survival rates of implants placed in sites augmented with mandibular bone. Methods: Seventy‐eight patients who received mandibular bone grafts were recalled after 18–42 months follow‐up (mean 29 months). The group consisted of 36 men and 42 women aged between 18 and 68 years old at the moment of augmentation surgery. Vitality of teeth adjacent to the harvesting sites was investigated. Soft tissue superficial sensory function was assessed by the Pointed‐Blunt Test and the Two‐Point‐Discrimination Test. Implant health status was assessed measuring peri‐implant probing depth and bleeding on probing. Implant survival and success rates were also calculated. In order to evaluate patients' perception of the morbidity of the procedures, the patients were asked to answer several questions by means of visual analogue scales (VAS). Results: Only two teeth (out of 282) in the chin harvesting group needed root canal treatment after surgery. A higher frequency of minor temporary and permanent sensorial disturbances was found in the group of patients who received chin harvesting procedures (2.3% vs. 13%P=0.03), while pain during chewing and bleeding were more frequently recorded after ramus harvesting (9.8% vs. 0%P=0.03). No permanent anesthesia of any region of the skin was reported. Implants' survival and success rate were comparable to implants placed in bone reconstructed with other techniques and were not influenced by the choice of the donor site. Patient's perception regarding the morbidity of the procedures was very low and did not differ between ramus and chin harvesting groups (mean VAS scores <4). Conclusion: The present cross‐sectional retrospective study demonstrated the safety of mandibular grafts that reported excellent results in terms of implant success and survival rates with minor complications regarding the donor site area. When the chin was chosen as donor site, minor sensorial disturbances of mucosa and teeth were recorded. The majority of these disturbances were temporary; only few of them were permanent but still had no impact on patient's life. To cite this article:
Cordaro L, Torsello F, Miuccio MT, Mirisola di Torresanto V, Eliopoulos D. Mandibular bone harvesting for alveolar reconstruction and implant placement: subjective and objective cross‐sectional evaluation of donor and recipient site up to 4 years.
Clin. Oral Impl. Res. 22 , 2011; 1320–1326.
doi: 10.1111/j.1600‐0501.2010.02115.x     

Bio-degradation of a resorbable collagen membrane (Bio-Gide®) applied in a double-layer technique in rats

Objective: The aim of this study was to evaluate histologically the bio‐degradation of two layers of Bio‐Gide^® (BG) membrane, as compared with that of a single layer. Material and methods: Two circular calvarial bony defects, 5 mm in diameter, were made in 24 Wistar rats. BG membrane, labeled with biotin, was cut into 5‐mm‐diameter disks, and placed in defects either as a mono‐layer membrane (MLM) or as a double‐layer membrane (DLM). Rats were sacrificed after 4 or 9 weeks and histology was performed. Membranes were stained with horseradish peroxidase‐conjugated streptavidin and aminoethyl carbazole as a substrate for detection of biotinylated collagen. The area of collagen and thickness of the residual membranes were measured by image analysis software. Statistical analysis was performed using the non‐parametric Wilcoxon's signed‐ranks test. Results: At 4‐week collagen area per measurement window within the DLM sites (0.09±0.05 mm²) was significantly greater (P<0.01) than that in the MLM sites (0.047±0.034 mm²). At 9 weeks, the collagen area was also greater in the DLM sites (0.037±0.026 mm²) compared with that of the MLM sites (0.025±0.016 mm²); however, this difference did not reach statistical significance. The rate of membrane degradation, calculated as percent membrane lost compared with baseline, was similar for the DLM and MLM at both time points (～60% at 4 weeks and ～80% at 9 weeks). In addition, the residual DLM thickness at 4 weeks (475.5±73.77 μm) was significantly (P<0.01) greater than that of MLM (262.38±48.01 μm). At 9 weeks, membrane thickness was also greater in the DLM sites (318.22±70.45 μm) compared with that of the MLM sites (183.32±26.72 μm); however, this difference did not reach statistical significance. The reduction in thickness between 4 and 9 weeks was 30% for MLM and 33% for DLM. Discussion: The use of a double layer of BG membrane results in a barrier of increased collagen area and thickness, compared with application of a single layer.     

Alveolar distraction osteogenesis vs. vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: a 1-3-year prospective study on humans

The purpose of this prospective study was to compare vertical guided bone regeneration (GBR) and vertical distraction osteogenesis (DO) for their ability in correcting vertically deficient alveolar ridges and their ability in maintaining over time the vertical bone gain obtained before and after implant placement. Eleven patients (group 1) were treated by means of vertical GBR with autogenous bone and e-PTFE membranes, while 10 patients (group 2) were treated by means of DO. In group 1, six patients received implants at the time of GBR (subgroup 1A), while five patients had implants placed at the time of membrane removal (subgroup 1B). In group 2, implants were placed at the time of distraction device removal. A total of 25 implants were placed in group 1 and 34 implants were placed in group 2 patients. Three to 5 months after implant placement, patients were rehabilitated with implant-borne dental prostheses. The following parameters were evaluated: (a) bone resorption of the regenerated ridges before and after implant placement; (b) peri-implant clinical parameters 1, 2, and 3 years after prosthetic loading of implants; (c) survival and success rates of implants. Bone resorption values before and after implant placement were significantly higher in group 1. The results suggested that both techniques may improve the deficit of vertically resorbed edentulous ridges, although distraction osteogenesis seems to be more predictable as far as the long-term prognosis of vertical bone gain is concerned. Implant survival rates as well as peri-implant clinical parameters do not differ significantly between the two groups, whereas the success rate of implants placed in group 2 patients was higher than that obtained in group 1 patients.