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PubMed1996

Guided bone regeneration to facilitate implant and prosthodontic therapy: three case reports.

In some patients, lack of bone at a desired fixture site has resulted, by necessity, in the placement of endosseous implants in less than favorable locations. The principles of guided bone regeneration can be used to restore lost alveolar bone and permit the placement of implants at more ideal locations, or to provide a more favorable ridge form to support a removable prosthesis. The advantages of a two-stage technique involving bone grafting followed by a healing period prior to implant placement are discussed. Different methods of membrane tenting to provide space for bone growth are illustrated by three case reports. Evidence of bone augmentation is provided by computed tomography.

Adult↗
PubMed2003

Guided bone regeneration around titanium plasma-sprayed, acid-etched, and hydroxyapatite-coated implants in the canine model.

BACKGROUND: Endosseous dental implants with rough surfaces have been designed to improve early healing, especially in areas of poor bone or insufficient bone quantity. The aim of this study was to histomorphometrically assess the bone-to-implant contact on 3 different rough-surfaced implants following guided bone regeneration. METHODS: Mandibular premolars and first molars were extracted in 12 dogs, and healing was allowed for 6 months. Six implant osteotomy sites were prepared, 3 per side, followed by the creation of 7.3 mm wide by 5 mm deep surgical defects in the coronal section of the osteotomy sites. Ten-mm long titanium screw-type implants with titanium plasma-sprayed (TPS), hydroxyapatite-coated (HA), or acid-etched (AE) surfaces were placed; the surrounding defects were filled with canine demineralized freeze-dried bone allograft; implants/grafts were covered with expanded polytetrafluoroethylene membranes; and the tissue was closed. Following a healing period of 4 months, the animals were sacrificed and mandibular blocks were harvested for histomorphometric analysis. RESULTS: The mean percentage of bone-to-implant contact in the defect and non-defect areas for the different implant surfaces was: AE 16.24% defect, and 28.78% non-defect; TPS 25.08% defect, and 16.96% non-defect; and HA 48.25% defect and 26.60% non-defect. Within the defect, the mean difference in the bone-to-implant contact was significant for HA compared to TPS (P < 0.0001) and HA versus AE (P < 0.0001); TPS versus AE was not significant (P = 0.063). In the non-defect areas, the mean difference in the bone-to-implant contact was significant for AE versus TPS (P = 0.010); all other comparisons were not significant. There were 18 membrane exposures in the 72 implant sites. Data were analyzed again to assess the impact of membrane complications. Using a 1-way analysis of variance, the bone-to-implant contact was compared between the sites with and without membrane complications. No significant differences were seen in the defect areas or in the non-defect areas between the sites with and without membrane complications. CONCLUSION: In this study, the bone-to-implant contact in regenerated bone was greatest when an HA-coated implant was used.

Acid Etching, Dental↗
PubMed2004

Guided bone regeneration may be negatively influenced by nicotine administration: a histologic study in dogs.

BACKGROUND: A series of animal and in vitro data confirms that nicotine impairs bone healing, diminishes osteoblast function, and causes autogenous bone graft morbidity. Therefore, this study aimed to investigate the impact of nicotine on the healing of bone defects treated by the guided bone regeneration (GBR) principle. METHODS: Sixteen mongrel dogs were used. One defect was surgically created bilaterally and randomly assigned as an expanded polytetrafluoroethylene (ePTFE) membrane site or a non-membrane control site. The animals were randomly assigned to one of the following groups: group 1, placebo (n = 8) and group 2, subcutaneous administration of nicotine (2 mg/kg) twice daily (n = 8). After 4 months, the animals were sacrificed and the specimens routinely processed for semi-serial decalcified sections. The evaluated parameters were bone height, bone width, bone density, and bone area of newly formed bone. RESULTS: Intergroup analysis (Kruskal-Wallis) showed that membrane-protected defects in the placebo group demonstrated an increased bone area when compared to membrane-protected defects in the nicotine group and non-membrane sites, regardless of nicotine administration (P < 0.05). In addition, nicotine administration significantly affected bone density in membrane- and non-membrane-protected sites (P < 0.05). CONCLUSIONS: Within the limits of the present study, nicotine might affect, but not prevent, bone healing in defects treated by guided bone regeneration. The mechanisms of this effect should be investigated further.

Alveolar Bone Loss↗
PubMed2000

[The bone regeneration process under chymotrypsin exposure (an experimental study)].

Disturbance of femur diaphysis compact substance was induced experimentally in rabbits. In the course of the operation single administration of crystalline chimotripsin into the wound was performed and its influence on bony structures regeneration was studied. Methods of light and scanning electron microscopy revealed that reparative processes started earlier and were more active than that in control. This promotes regenerate formation and complete healing of bone defect. Intramuscular administration of proteolytic enzyme does not exert essential influence on bone regeneration.

Animals↗
PubMed1998

Recombinant human bone morphogenetic protein-2 and collagen for bone regeneration.

The study reported describes a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen (C) to regenerate bone. Unilateral critical-sized defects (CSDs) were prepared in radii of 32 skeletally mature New Zealand white rabbits. Rabbits were divided evenly among four treatments: autograft, absorbable C (Helistat), 35 microg of rhBMP-2 combined with absorbable C (rhBMP-2/C), and untreated CSDs. The two euthanasia periods were 4 and 8 weeks. Radiographs were taken the day of surgery, every 2 weeks, and at term and the percent of radiopacity was measured. Data analysis revealed a time-dependent increase in the percent radiopacity with rhBMP-2/C. Histological examination revealed the rhBMP-2/C treatment regenerated osseous contour by 8 weeks. According to quantitative histomorphometry, the CSD and C groups had significantly less new bone than either autograft or rhBMP-2/C (p < or = 0.05). The results suggest that rhBMP-2/C could be an effective therapy to restore segmental bone defects.

Animals↗
PubMed2004

[Experimental study on guiding bone regeneration with bovine pericardium membrane].

OBJECTIVE: To explore the feasibility of bovine pericardium used as a material for guiding bone regeneration. METHODS: 1 cm x 1 cm x 0.5 cm defects were created on both buccal sides of the mandibles of 11 dogs. One side was covered with Glutaraldehyde (GA) cross-linking bovine pericardium; no membrane covered side was used as control. The animals were sacrificed in 2 weeks, 4 weeks, 8 weeks and 16 weeks after operation to observe the repair of the bone defects. RESULTS: (1) Wounds healed well in 10 dogs. Meanwhile, wounds in dogs of 16 weeks group healed badly and severe inflammatory response was found in bovine pericardium treated area. (2) The pericardium can be maintained in vivo for 16 weeks without absorption, there were only mild inflammatory cells invading. (3) The bone defects covered with bovine pericardium repaired better than control groups significantly. CONCLUSION: (1) GA bovine pericardium have the effect on guiding bone regeneration in the repair of dog experimental bone defects and it is possible that the bovine pericardium will be used as a new kind of GBR material; (2) GA bovine pericardium has good biocompatibility.

Animals↗
PubMed2000

Simultaneous and staged approaches for guided bone regeneration.

Two approaches for obtaining bone augmentation around implants by guided tissue regeneration are described. In the first, bone is regenerated simultaneously with implant placement, which is a time saving tactic. However, when initial stability of the implant cannot be obtained because of insufficient bone volume, a staged approach must be considered. In the staged approach, the bone is augmented and the implant is inserted later. The staged approach offers improved primary stability, allows the implant to be inserted in mature bone, and enables examination of the newly augmented bone before a decision is made whether or not to use it as an implant site. Two case reports are presented which illustrate the approaches.

Adolescent↗
PubMed2001

[Risks and complications of membrane-guided bone regeneration. Retrospective analysis].

AIM OF THE STUDY: The aim of this retrospective study was to determine the number of premature membrane exposures and to evaluate possible predisposing factors. PATIENTS AND METHODS: A total of 72 patients were treated with ePTFE membranes (GoreTex Augmentation Material) for membrane-guided bone regeneration (GBR) of periimplant bone defects (median age 38.5 years, minimum 18 years, maximum 68 years; 39% male and 61% female patients, data collection between 03/1993 and 02/2000). Sixty-one percent of the membranes were applied in the upper jaw and 39% in the lower jaw; 61% of all GBR procedures were performed in conjunction with single tooth replacements. RESULTS: Premature membrane exposure (PME) was found at 44% of the sites. Of these PMEs 72% occurred after a primary, uneventful healing period subsequent to membrane implantation. Statistical analysis revealed a significant correlation between the parameters "premature membrane exposure", "membrane covering the alveolar ridge" (P = 0.0004) and "membrane located beneath the incision line" (P = 0.0004). Additionally a tendency for correlation was calculated for the parameters "defect configuration" (P = 0.08) and "smoking" (P = 0.04). CONCLUSIONS: The defect morphology, the flap and incision design and the smoking habits of the patients have to be carefully considered if guided bone regeneration is planned. Non-space-maintaining defect configurations, smoking habits and crestal incisions crossing the planned membrane location seem to be contraindications for the use of ePTFE membranes. In such cases, alternative treatment methods should be considered.

Adolescent↗
PubMed2003

Le Fort I osteotomy in atrophied maxilla and bone regeneration with pure-phase beta-tricalcium phosphate and PRP.

Le Fort I osteotomy is a versatile procedure in oral and maxillofacial surgery for the correction of dysgnathias as well as for an easy approach to the surgical site in neurosurgery; however, it is rarely performed for a vertical advancement of the maxilla. This paper presents the successful use of the synthetic pure-phase beta-tricalcium phosphate (beta-TCP) Cerasorb (Curasan, Kleinostheim, Germany), together with autogenous bone at a ratio of 4:1, in combination with patients' own platelet-rich plasma for a vertical augmentation of completely atrophied maxillae, resulting in an advancement of 16 and 14 mm, respectively. After a period of 8 months the beta-TCP was completely resorbed and the x-ray control showed no residual granules in the defect sites. Pure-phase beta-TCP proved to be a bone-regeneration material, providing the patient with vital bone at the defect site in a reasonable time, making a second surgical procedure for bone harvesting (e.g., at the iliac crest) unnecessary. The relapse of approximately one third in the second case did not affect the success of treatment and was attributed to the combination of platelet-rich plasma with a resorbable polylactic membrane. Thus, in the combination of pure-phase beta-TCP and platelet-rich plasma, the use of nonresorbable membranes and suture materials is recommended. These results encourage the qualified surgeon to use the pure-phase beta-TCP for bone regeneration even when performing augmentations of this dimension.

Alveolar Bone Loss↗
PubMed1998

Age-related changes on bone regeneration in midpalatal suture during maxillary expansion in the rat.

The purpose of the present study was to investigate age-related changes in bone regeneration during expansion of a midpalatal suture in rats. When the midpalatal suture was expanded for 7 days in rats of four different ages (6, 15, 24, and 52 weeks), it was found to have significantly widened in all groups by the analysis of a histomorphometric method. The expansion-induced widening of the suture was similar in 6, 15, and 24-week-old rats but was significantly less in 52-week-old rats. When the newly mineralized bone area and the osteoid area along the suture in all groups were quantified, newly mineralized bone area in all expansion groups significantly increased compared with corresponding controls, but expansion-induced newly mineralized bone area decreased in an age-dependent manner. Osteoid area also significantly increased by expansion, but expansion-induced osteoid area unexpectedly increased with age up to the 24-week-old rats. In the expansion-induced total bone area (expansion-induced newly mineralized bone area plus osteoid area), there was no significant difference among 6, 15, and 24-week-old rats, but it was markedly decreased in 52-week-old rats. Alkaline phosphatase activity in the suture strongly increased in all expansion groups, whereas increase in the rate of alkaline phosphatase activity clearly was less in 24 and 52-week-old rats. These results suggested that the difficulty of rapid-palatal expansion in 52-week-old rats and age-related decrease in bone regeneration after expansion of the suture within 24-week-old rats may be caused by decrease in mineralization of the bone matrix. Therefore, midpalatal suture can expand even in the cases exceeding the pubertal growth period, but more time may be necessary for mineralized bone to regenerate in the suture.

Age Factors↗
PubMed1998

Guided bone regeneration utilizing expanded polytetrafluoroethylene membranes in combination with submerged and nonsubmerged dental implants in beagle dogs.

Treatment of partial and total edentulism with submerged and nonsubmerged dental implants which follows the concept of osseointegration has become an accepted treatment modality. With compromised implant sites, practitioners have begun to combine one-stage implants with established techniques including guided bone regeneration. However, the clinical evaluation of this technique is limited. Therefore, the purpose of this study was to evaluate osseointegration and bone regeneration around nonsubmerged or submerged implants placed directly into surgically created osseous defects with or without expanded polytetrafluoroethylene (ePTFE) membranes. A total of 24 implants were placed in the mandibles of 4 beagle dogs and randomly assigned to 1 of 3 treatment groups. In group A, nonsubmerged implants were placed into osseous defects and treated with a poncho style ePTFE membrane. These membranes had a hole punched into the center and were slipped over the nonsubmerged implants. In group B, nonsubmerged implants were placed into osseous defects without an ePTFE membrane. In group C, submerged implants were placed into osseous defects and covered with an ePTFE membrane. Histometric measurements of each treatment group were made to determine percent bone gain or loss along the implant surface. Although a number of membrane removals occurred during the healing period, histological analysis indicated osseous ingrowth and osseointegration around nonsubmerged and submerged implants. An overall comparison of the treatment groups with ANOVA revealed that there were no significant differences between treatment groups, P > or = 0.05. However, when the data were stratified into sites which retained or lost the ePTFE membrane, the percent of bone regeneration was reduced in group A. Therefore, it may be recommended that nonsubmerged implants be placed with a submerged or "semi-submerged" protocol when utilized in conjunction with ePTFE membranes.

Animals↗
PubMed2002

[A clinical and histological study of Bio-Oss in combination with guided bone regeneration membrane technique].

OBJECTIVE: To evaluate the reliability of Bio-Oss particles as bone grafts in combination with membrane-technique. METHODS: 6 small biopsy specimens were retrieved without causing iatrogenic damage in 6 patients (implant sites). The Donath's hard tissue section and micro grinding technique was adopted, and Leval Laczko staining method was used. RESULTS: The histological results showed Bio-Oss particles were easily distinguished from the newly formed bone, but new bone was formed among different particles of Bio-Oss, no connective tissue was found. Intimate contact between newly formed bone and particles of the graft was present. CONCLUSIONS: Bio-Oss appears to be highly biocompatible and osteoconductive. It can be used success fully as a bone substitute in combination with guided bone regeneration membrane technique.

Adult↗
PubMed2004

Comparison of canine mandibular bone regeneration by distraction osteogenesis versus acute resection and rigid external fixation.

The present study was performed (1) to explore the mechanism of skeletal healing following distraction osteogenesis of the mandible and to evaluate whether the same process is involved following acute mandibular resection and rigid external fixation, and (2) to examine the role of the periosteum in skeletal healing in both models. The study was performed using 16 mongrel dogs divided into two equal groups. In the first group, distraction of 20 mm was performed at a rate of 1 mm/day. In the second group, bone resection of 20 mm was performed, followed by rigid external fixation. The buccal periosteum was stripped in four dogs from each group, and the periosteum was left intact in the remaining four dogs. Dogs were euthanized after a survival period of either 2 or 3 months, and the new bone regenerate was evaluated. Analysis consisted of three-dimensional computed tomography scanning, histometric analysis, and immunostaining. Analysis of bone mineral content in the residual gap was conducted. Bone mineral content was increased in 3- versus 2-month survival for all groups (p < 0.05). The distracted groups had greater bone mineral content than their acutely resected counterparts, with the difference achieving statistical significance by 3-month survival (p < 0.05). Although periosteal preservation resulted in increased bone mineral content over time for all groups (p = 0.044), periosteal preservation had no significant effect on bone mineral content in the distracted groups. After periosteal stripping, however, bone mineral content was significantly increased in dogs that underwent distraction rather than acute resection and rigid external fixation (p = 0.022). Regarding histometric analysis, analysis of fibrous tissue content in the bone regenerate demonstrated that by 3 months the distracted groups had significantly less fibrous tissue in the new bone regenerate than did the acutely resected groups (p < 0.001). Regarding immunostaining, diffuse localization of transforming growth factor-beta1 was observed in all groups at 2 months, returning to nearly baseline levels by 3 months. These data demonstrate that significant bone formation in a segmental gap can be achieved after acute mandibular resection and rigid external fixation if the periosteum is preserved. However, after periosteal injury or stripping, significant bone formation can only be achieved by distraction osteogenesis. In both processes, bone formation is preceded by up-regulation of transforming growth factor-beta1.

Animals↗
PubMed2004

Strong and rapid induction of osteoblast differentiation by Cbfa1/Til-1 overexpression for bone regeneration.

Core binding factor alpha-1 (Cbfa1), known as an essential transcription factor for osteogenic lineage, has two major N-terminal isoforms: Pebp2alphaA and Til-1. To study the roles of these isoforms in bone regeneration, we applied an adenoviral vector carrying their genes to transduce primary osteoprogenitor cells in vitro and in vivo. Overexpression of the two isoforms induced rapid and marked osteoblast differentiation, with Til-1 being more effective in vitro, by examination of the alkaline phosphatase activity, calcium content, and Alizarin red staining. Til-1 overexpressing cells/porous ceramic composites were transplanted into subcutaneous and bone defect sites in Fischer rats (cultured bone transplantation model) and markedly affected in vivo bone formation and osteoblast markers. The results demonstrated that the reconstitution of bone tissues, such as cortical bone and trabecular bone was accelerated by implantation of Til-1 overexpressing cells/porous ceramic composites. Moreover, the new bone formation by Til-1 overexpression appeared to reflect replacement of new bone within the implant boundaries. To ascertain whether implanted Cbfa1 overexpressing cells could differentiate into osteogenic cells to create bone or whether it stimulated the surrounding recipient tissue to regenerate bone, implanted male donor cells were visualized by fluorescent in situ hybridization analysis. The proportion of implanted cells in the presumptive bone forming region was over 80% and did not change throughout from 3 days to 8 weeks after implantation. These findings suggested that the newly formed bone in the porous area of the scaffold is mostly produced by the implanted donor cells or their derived cells, effectively by Til-1 overexpression.

Adenoviridae↗
PubMed2006

Segmental bone regeneration using a load-bearing biodegradable carrier of bone morphogenetic protein-2.

Segmental defect regeneration has been a clinical challenge. Current tissue-engineering approach using porous biodegradable scaffolds to delivery osteogenic cells and growth factors demonstrated success in facilitating bone regeneration in these cases. However, due to the lack of mechanical property, the porous scaffolds were evaluated in non-load bearing area or were stabilized with stress-shielding devices (bone plate or external fixation). In this paper, we tested a scaffold that does not require a bone plate because it has sufficient biomechanical strength. The tube-shaped scaffolds were manufactured from poly(propylene) fumarate/tricalcium phosphate (PPF/TCP) composites. Dicalcium phosphate dehydrate (DCPD) were used as bone morphogenetic protein-2 (BMP-2) carrier. Twenty-two scaffolds were implanted in 5mm segmental defects in rat femurs stabilized with K-wire for 6 and 15 weeks with and without 10 microg of rhBMP-2. Bridging of the segmental defect was evaluated first radiographically and was confirmed by histology and micro-computer tomography (microCT) imaging. The scaffolds in the BMP group maintained the bone length throughout the duration of the study and allow for bridging. The scaffolds in the control group failed to induce bridging and collapsed at 15 weeks. Peripheral computed tomography (pQCT) showed that BMP-2 does not increase the bone mineral density in the callus. Finally, the scaffold in BMP group was found to restore the mechanical property of the rat femur after 15 weeks. Our results demonstrated that the load-bearing BMP-2 scaffold can maintain bone length and allow successfully regeneration in segmental defects.

Animals↗