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At least 397 records · Page 22Linked to original sources
PubMed2006

Bone regeneration in dehiscence-type defects at chemically modified (SLActive) and conventional SLA titanium implants: a pilot study in dogs.

OBJECTIVES: The aim of the present study was to evaluate bone regeneration in dehiscence-type defects at titanium implants with chemically modified (mod) and conventional sand-blasted/acid-etched (SLA) surfaces. MATERIAL AND METHODS: Standardized buccal dehiscence defects (height: 3 mm, width: 3 mm) were surgically created following implant site preparation in both the upper and lower jaws of four beagle dogs. modSLA and SLA implants were inserted bilaterally according to a split-mouth design. The animals were sacrificed after 2 and 12 weeks (n=2 animals each). Dissected blocks were processed for histomorphometrical analysis: defect length, new bone height (NBH), percent linear fill (PLF), percent of bone-to-implant contact (BIC-D) and area of new bone fill (BF). RESULTS: Wound healing at SLA implants was predominantly characterized by the formation of a dense connective tissue at 2 and 12 weeks, without significant increases in mean NBH, PLF, BIC-D or BF values. In contrast, modSLA implants exhibited a complete defect fill at 12 weeks following implant placement. In particular, histomorphometrical analysis revealed the following mean values at 12 weeks: NBH (3.2+/-0.3 mm), PLF (98%), BIC-D (82%) and BF (2.3+/-0.4 mm(2)). CONCLUSION: Within the limits of the present study, it was concluded that modSLA titanium surfaces may promote bone regeneration in acute-type buccal dehiscence defects at submerged implants.

Acid Etching, Dental↗
PubMed2004

Reproducibility and accuracy of automated probe measurements of gingiva and bone levels on stone casts following guided bone regeneration treatment.

OBJECTIVES: For evidence-based evaluation of guided bone regeneration (GBR), accurate registration of changes in gingiva and bone levels is needed. A new method is introduced and evaluated. METHODS: In a clinical trial with 30 patients, alginate impressions of the surgical area including the interproximal gingiva and alveolar bone at the adjacent teeth were made in duplicate prior to and during GBR surgery, fixture installation and abutment connection. Poured in hard stone, the casts were used for repeated measurements of the level of the free gingival margin and the alveolar bone with an automated probe (Florida disc-probe(R)), using the incisal edge as a fixed reference point. The reproducibility and accuracy of these measurements were evaluated by means of the Intraclass Correlation Coefficients and Generalizability Theory. The effect of treatment was evaluated by multivariate analysis of variance. RESULTS: Generalizability Theory indicated a high accuracy of the gingiva- and bone-level measurements: the Intraclass Correlation Coefficients for gingiva and bone levels were 0.99 and 0.98, respectively. The intra-cast reproducibility was 0.09+/-0.07 mm (mean+/-SD) and the inter-cast reproducibility was 0.10+/-0.09 and 0.20+/-0.07 mm for gingiva and bone levels, respectively. Clinical applicability is demonstrated by the fact that manova revealed on average a small but highly significant (p=0.001) effect of the staged surgical intervention on the gingiva and bone levels at the adjacent teeth. CONCLUSION: It is concluded that the presented method makes it possible to evaluate reproducibly and accurately changes in gingiva and bone levels for GBR studies.

Alveolar Bone Loss↗
PubMed2000

A histochemical investigation of the bone formation process by guided bone regeneration in rat jaws. Effect of PTFE membrane application periods on newly formed bone.

BACKGROUND: Guided bone regeneration (GBR) has been widely utilized for the promotion of bone augmentation in bone loss areas. However, little information has been available regarding chronological changes in newly formed bone and alterations in the nature of newly formed bone after removal of a barrier membrane. The present study attempted to establish a GBR model for rat maxillae. We also examined the effects of membrane application periods on newly formed bone and its remodeling process after removal of the membrane in this experimental model. METHODS: Thirty-five Wistar rats were divided into 2 groups: a membrane application group and a membrane removal group. The chronological changes of newly formed bone were evaluated histologically and statistically. RESULTS: At 2 weeks after the GBR procedure, bony cavities had completely filled the newly formed bone in the experimental side. In the control side, corticalization on the surface of the newly formed bone proceeded with a decrease in the bone marrow cavity, whereas the bone marrow space had enlarged by 12 weeks post-surgery in the experimental side. In the membrane removal group, the osteoblasts appeared on newly formed bone at 1 week after membrane removal. Comparatively thick compact bone had formed on the surface of the newly formed bone at 4 weeks after membrane removal, and corticalization proceeded later. CONCLUSIONS: The long-term application of a barrier membrane induces the enlargement of the bone marrow spaces. We suggest that PTFE membrane removal in adequate time promotes the corticalization and maturation of the newly formed bone by the GBR technique.

Acid Phosphatase↗
PubMed2004

Effects of cortical bone perforation on experimental guided bone regeneration.

This study was designed to evaluate the effects of cortical bone perforation histologically and histomorphometrically on guided bone regeneration (GBR) in rabbits. After elimination of the periosteum, cortical bone defects of two sizes were made in the external cortical plate of the frontal bone (Group A: 1 x 15 mm; Group B: 3 x 15 mm). A non-resorbable membrane filled with autogenous blood was placed in the experimental area and secured with titanium pins. After 1 and 2 weeks, vascularized connective tissue and new bone were generated in the space surrounding the defects in both the groups. The amount of vascularized connective tissue generated in Group B was greater than that in Group A at 1 week. Alkaline phosphatase (ALP) was expressed on the bone surrounding the perforation. The expression of ALP was more extensive in Group B than in Group A and was proportional to the breadth of perforation. At 2 weeks, the perforated region was almost covered with new bone in Group A. ALP was expressed at the periphery of newly formed bone. The expression of ALP was proportional to the breadth and height of perforation. At 6 weeks, semicircular outgrowth of bone towards the periphery of the perforated region was observed in both the groups. Newly formed bone volume and ALP expression in Group B were more extensive than those in Group A. At 12 weeks, the space was filled with bone and connective tissue in both the groups. There was no difference in ALP expression between Groups A and B. Histomorphometric analysis showed significant differences between both the groups (two-way ANOVA, P<0.01). We conclude that a larger perforation is associated with prompter bone formation in the secluded space during GBR.

Alkaline Phosphatase↗
PubMed2000

[Histological study on the polyhydroxybutyric ester(PHB) membrane used for guided bone regeneration around titanium dental implants].

OBJECTIVE: To evaluate the effects of PHB membrane around dental titanium implants used in guided bone regeneration technique. METHODS: Endosseous cylindrical implants were placed in dogs' mandibles after extraction of all the mandibular premolars and the first molars immediately. Ideal implant placement sites were modified by creating standardized 3 mm x 5 mm facial dehiscent defects. The defects were covered with PHB membrane and titanium membrane respectively, then the membranes were fixed on the periosteum by sutures, and the remainder served as controls. Tissue closure was achieved with mattress and interrupted single sutures, and antibiotic injection was given to the dogs in the following 3 days. The dogs were divided into three groups according to the healing time of 1, 2 and 3 months, then the three groups of dogs were sacrificed. After that, tissue blocks containing the implants and the control ones were removed and studied by gross observation, X-ray radiograph and fluorescence microscope, and the surfaces of the membranes were observed by scanning electron microscope. The specimen used for light microscope study were fixed with 10% formaldehyde for 24 hours, and decalcified with 0.5 mol/L EDTA for 2 weeks. After the titanium implants were carefully removed, the tissue blocks were embedded into the paraffin wax, and the sections were obtained. RESULTS: The PHB membrane degraded slowly and partly 3 months after placement, and the biodegradable property of the PHB membrane deserved a longer period of study; The bone defects covered with PHB and titanium membrane were filled with much more new bone than that of the control group. CONCLUSION: PHB membrane can enhance bone formation and can be used for guided bone regeneration.

Animals↗
PubMed1998

Evaluation of a new bioresorbable barrier to facilitate guided bone regeneration around exposed implant threads. An experimental study in the monkey.

The aim of this study was to evaluate the effectiveness of a new bioresorbable barrier alone or in combination with BioOss for guided bone regeneration around dental implants with exposed implant threads. Five adult Macaca fascicularis monkeys were used in this investigation. After extraction of all premolars and first molars, two endosteal oral implants were installed in each quadrant and the bony defects were randomly treated with either: 1) placement of the new bioresorbable device alone (group 1); 2) placement of the new bioresorbable barrier in combination with BioOss (group 2); 3) placement of an ePTFE barrier in combination with BioOss (group 3); or (4) control (group 4). After a period of six months the animals were killed and the histological processing was performed. There was a significant difference in the amount of new bone regeneration around the implants between the four groups (i.e. groups 1, 2, 3 and 4) (P=0.0122). There was no difference, however, between group 2 and group 3. It can be concluded that the new bioresorbable barrier in combination with BioOss appears to obtain the same results in this type of bony defects as the grafting material in combination with an ePTFE barrier.

Animals↗
PubMed1999

The use of titanium plates for bone regeneration with root form implants: a case report.

In reconstruction of the partially and totally edentulous ridges that have bony defects due to old trauma or longstanding atrophy, it is necessary to reconstruct both the width and height of the alveolar ridge. This clinical case report covers bone regeneration prior to implant placement to achieve an aesthetic and functional base for prosthetic restoration. The focus of this report will be on bone regeneration, which does not depend on the utilization of a barrier membrane.

Adult↗
PubMed2001

Locally delivered rhTGF-beta2 enhances bone ingrowth and bone regeneration at local and remote sites of skeletal injury.

The purposes of the present study were to determine if recombinant human transforming growth factor-beta-2 (rhTGF-beta2) enhances bone ingrowth into porous-coated implants and bone regeneration in gaps between the implant and surrounding host bone. The implants were placed bilaterally for four weeks in the proximal humeri of skeletally mature, adult male dogs in the presence of a 3-mm gap. In three treatment groups of animals, the test implant was treated with hydroxyapatite/tricalcium phosphate (HA/TCP) and rhTGF-beta2 in buffer at a dose per implant of 1.2 microg (n = 6), 12 microg (n = 7), or 120 microg (n = 7) and placed in the left humerus. In these same animals, an internal control implant treated only with HA/TCP and buffer was placed in the right humerus. In a non-TGF-beta treated external control group of animals (n = 7), one implant was treated with HA/TCP while the contralateral implant was not treated with the ceramic. In vitro analyses showed that approximately 15%, of the applied dose was released within 120 h with most of the release occurring in the first 24 h. The TGF-beta treated implants had significantly more bone ingrowth than the controls with the greatest effect in the 12 microg/implant group (a 2.2-fold increase over the paired internal control (P = 0.004) and a 4-fold increase over the external control (P < 0.001)). The TGF-beta treated implants had significantly more bone formation in the gap than the controls with the greatest effect in the 12 and 120 microg groups (1.8-fold increases over the paired internal controls (P = 0.003 and P = 0.012, respectively) and 2.8-fold increases over the external controls (P < 0.001 and P = 0.001, respectively)). Compared to the external controls, the internal control implants tended to have more bone ingrowth (1.9-fold increase, P = 0.066) and had significantly more bone formation in the gap (1.7-fold increase. P = 0.008). Thus, application of rhTGF-beta2 to a porous-coated implant-stimulated local bone ingrowth and gap healing in a weakly dose-dependent manner and stimulated bone regeneration in the 3-mm gap surrounding the contralateral control implant, a site remote from the local treatment with the growth factor.

Animals↗
PubMed2005

Blood-filled spaces with and without deproteinized bone grafts in guided bone regeneration. A histomorphometric study of the rabbit skull using non-resorbable membrane.

This experimental study evaluated the effects of deproteinized bone grafts on guided bone regeneration (GBR). A groove was made in the bone marrow of the external cortical plate of the skull. A dome of non-resorbable membrane was placed on the groove and secured with titanium pins. The secluded graft space was filled with autogenous blood clots (control group) and deproteinized bone particles (experimental group). The rabbits were sacrificed 2, 4, 8 and 12 weeks after the operation. Decalcified and paraffin-embedded, transverse 3-mum-thick sections were made and stained with hematoxylin and eosin. The proportions of newly formed bone and newly formed bone-graft particle contact surfaces were histomorphometrically measured in the basal, central, and peripheral areas from the cortical plate to the top of the dome. In the control group, the basal area showed a significant increase at 4 weeks (P<0.01) and a significant decrease at 8 weeks (P<0.01). The central and peripheral areas showed gradual increases in the proportion of newly formed bone. The experimental group showed significant increase at 4 weeks in the basal area and at 8 weeks in central and peripheral area (P<0.01). There were significant differences between both groups in basal and central area (P<0.01). The proportion of newly formed bone-graft particle contact length showed significant increases at 4 weeks (P<0.01) and no significant decreases at 8 and 12 weeks in three areas. The present study showed that deproteinized bone grafts maintain newly formed bone in extensive areas for a prolonged period during GBR.

Animals↗
PubMed2005

Osteogenesis and angiogenesis in regenerating bone during transverse distraction: quantitative evaluation using a canine model.

For some patients with a bone defect, curved deformity, or small diameter bone, transverse distraction might be better indicated than bone transport or lengthening. However, detailed quantitative evaluation of osteogenesis or angiogenesis during transverse distraction by creating a well-controlled animal model has not been done. We established a transverse distraction model of the canine tibia. A rectangular cortex was separated for a distraction fragment. Seven days after the operation, 0.5-mm distraction was applied twice daily for 14 days. After a 28-day consolidation period, the animals were sacrificed. Quantitative evaluations of the rates of mineralization and the increases of bone mineral density indicated faster mineralization and earlier corticalization of the regenerating bone in the initial stage of the consolidation period. The average blood vessel volume ratio in the distraction area was more than three times greater than in the intact contralateral tibiae. We hypothesized that adequate preservation of the marrow arteries and stability of the distraction site throughout an experimental period could induce this faster osteogenesis. Our results indicated that the transverse distraction technique was feasible. The transverse distraction technique could be indicated for patients with small-diameter bones or with massive bone defects.

Animals↗
PubMed2003

In vivo evaluation of gene therapy vectors in ex vivo-derived marrow stromal cells for bone regeneration in a rat critical-size calvarial defect model.

Cells genetically modified to produce osteoinductive factors have potential for use in enhancing bone regeneration for reconstructive applications. Genetic modification of cells can be accomplished by a variety of gene therapy vectors. In this study we evaluated the ex vivo genetic modification of rat marrow stromal cells (MSCs) by adenoviral, retroviral, and cationic lipid vectors containing the gene for human bone morphogenetic protein 2 (hBMP-2). We investigated both the in vitro and in vivo osteogeneic potential of MSCs modified by each vector. In vitro, we found that only MSCs modified with the adenoviral vector produced detectable hBMP-2 and demonstrated a statistically significant increase in endogenous alkaline phosphatase activity indicative of osteogeneic differentiation. We further investigated the ability of genetically modified MSCs seeded on a titanium mesh scaffold to facilitate bone formation in vivo. In an orthotopic critical-size defect created in the rat cranium, bone formation was observed in all conditions with MSCs modified by the adenoviral vector demonstrating a small but statistically significant increase in bone formation relative to the other vectors and control. Implants in an ectopic location demonstrated minimal bone formation relative to the orthotopic location, with MSCs modified with cationic lipids forming less bone than the other vectors and control. Our results show that MSCs genetically modified with adenovirus containing the hBMP-2 gene had enhanced osteogeneic capacity relative to unmodified MSCs or MSCs modified by the other vectors. This study was the first to compare three different gene therapy vectors for the genetic modification of cells to produce osteoinductive factors for the purpose to enhance bone regeneration.

Adenoviridae↗
PubMed1996

[Cherubism: regression of the lesions and spontaneous bone regeneration].

Three cases of cherubism belonging to the same genealogical tree which had been followed up since the age of 7 years to adulthood are presented. These cases prove that, without treatment, the regression of the lesions and bone regeneration are real and not anecdotal. Nevertheless, following spontaneous bone regeneration, radiographically some radiolucent areas of low intensity and devoid of trabeculations, and/or areas of sclerotic bone do persist. In one case, cherubism was associated with peripheral giant cell granulomas localized in areas not affected by cherubism.

Adult↗
PubMed2004

Role of guided bone regeneration principle in preventing fibrous healing in distraction osteogenesis at high speed: experimental study in rabbit mandibles.

The formation of fibrous tissues at the distraction gap may result from the accumulation of rapidly migrating fibroblasts at the site of an osteotomy, especially when distraction is rapid. Addition of osteopromotive membranes could theoretically prevent fibroblasts from entering the distraction gap, allowing the osteotomy site to be filled with only osteogenic cells. This study is an attempt to achieve a rapid successful distraction without fibrosis through the use of collagen membranes. Sixteen skeletally mature New Zealand white rabbits were used in this study. They were divided into two groups. One rabbit from each group was excluded from the study because of dislodgement of the distractors. In one group (n = 7), distraction was done as usual. In the other group (n = 7), a collagen membrane surrounded the osteotomy site to be distracted. After a 7-day latency period, distraction started at a rate 2 mm once per day for 5 days. The distractor was left in place for 4 weeks to allow consolidation. Results showed osteogenesis in both groups. Whereas addition of the membrane to distraction increased the quantity of bone formed, absence of the membrane allowed early mineralization (better quality of bone regarding the density). Neither of the two groups showed significant fibrosis or cartilage formation. The endosteum served as a source of blood supply when the periosteum was excluded. The periosteum served as a membrane for guided bone regeneration. Membranes for guided bone regeneration can be used with distraction when the periosteum is lost from trauma or is broken from fast distraction.

Animals↗
PubMed2007

Clinical significance of incision location on guided bone regeneration: human study.

BACKGROUND: Membrane exposure has been associated with poor clinical outcomes in guided bone regeneration. This prospective human study examined the effect of incision locations on flap survival and membrane exposure. METHODS: Twenty-nine implant-associated buccal dehiscence defects in 25 patients were augmented using particulate mineralized human allograft. Ten sites received a collagen bioabsorbable membrane, 10 sites received acellular dermal matrix, and nine sites were treated with bone graft alone. All implants achieved primary stability and passive flap tension at the time of flap closure. Incision location was measured as the distance from the initial incision line to the mucogingival junction. The same measurements were made at 2 weeks and 1 month to represent the length of the flap that survived. The length of the flap that survived at 2 weeks was compared to the mean width of buccal keratinized gingiva (KG) of adjacent teeth. Other clinical parameters recorded included incidence of early membrane exposure and gingival thickness at mid-crest and 6 mm buccal and lingual to the mid-crest at baseline. RESULTS: At 2 weeks, 10 sites experienced early exposure. Exposed sites that were not covered by 1 month remained exposed. Membrane-treated groups showed no significant difference between the width of adjacent buccal KG and the length of the flap that survived at 2 weeks. The length of the flap that survived beyond the mean width of adjacent KG was significantly greater for the graft alone group (1.6 +/- 0.4 mm; P = 0.002). When the gingival thicknesses of exposed and non-exposed cases were compared, only palatal/lingual gingival thickness showed a significant difference (P = 0.002). CONCLUSIONS: Within the limits of the study, it was concluded that the location of the crestal incision might be a significant factor in reducing the incidence of membrane exposure by minimizing flap necrosis. The mean KG width of adjacent teeth may be used as a guide to determine the initial incision location. However, this effect may be less significant in palatal/lingual gingiva >3.0 mm.

Adult↗
PubMedDate not supplied

Tomodensitometric and histologic evaluation of the combined use of a collagen membrane and a hydroxyapatite spacer for guided bone regeneration: a clinical report.

In this report, the problems of insufficient bone and soft tissue after extraction of maxillary incisors were addressed concurrently prior to endosseous implant placement, by combining the use of a diphenylphosphorylazide-cross-linked Type I collagen membrane and a resorbable space-making biomaterial composed of 200-micron porous hydroxyapatite granules blended in Type I collagen and chondroitin-4-sulfate. Upon flap reflection 8 months postsurgery, the horizontal deficiencies were almost completely resolved, membranes completely resorbed and the defects filled with hard, bonelike tissue, with a few superficial hydroxyapatite granules. Histologic evaluation of the bone biopsies obtained at the implantation sites revealed dense, well-reconstructed alveolar bone with a few traces of hydroxyapatite granules that had been completely resorbed. Tomodensitometric evaluation indicated that bone regeneration ranged from 14% to 58%, with an average bone gain of 29.77%. Four nonsubmerged ITI titanium implants placed in the augmented bone have been in function for more than 5 years, with no clinical or radiographic signs of hard or soft tissue breakdown. Bacterial sampling at dental sites with periodontitis 1 month prior to periodontal therapy and at implant sites for up to 30 months demonstrated rapid colonization of implant surfaces by periodontopathogens without causing any detrimental effect to implant integration.

Absorbable Implants↗
PubMed2002

[Bone regeneration and Mesenchymal stem cells].

Bone marrow mesenchymal stem cells have been considered to differentiate into cells in bone, cartilage, tendon, muscle, and fat. Further analyses revealed that these cell also give rise to myocardial cells, oval cells and nerve cells, indicating high plasticity of these cells. Recent researches have been focused to utilize these cells to regenerate not only bone but also the life-maintaining major organs. As a cell source for the future regeneration of multiple organs, regeneration of the bone marrow is critical and thus studies on the process of bone marrow regeneration will benefit not only bone physiology field alone but also that of many other organs.

English Abstract↗
PubMed1991

Bone regeneration using the principle of guided tissue regeneration.

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

Alveolar Process↗