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PubMed2006

Enhanced bone regeneration by electrical polarization of hydroxyapatite.

We examined osteogenic cell responses and new bone formation on electrically polarized hydroxyapatite (HAp) plates implanted into calvarial bone defects in rats. In the first group of rats, test pieces were placed with their positively charged surfaces face down on the dura mater. In a second group, test pieces were placed with their negatively charged surfaces facedown on the dura mater. A third group received noncharged test pieces. Histological examination was carried out to characterize the newly formed bone as well as quantification. Enzyme histochemistry involving the detection of alkaline phosphatase and tartrate-resistant acid phosphatase was performed to quantify osteogenic cell activity. Bone growth was enhanced in the groups that received polarized HAp plates, both at the negatively and positively charged surfaces. In addition to the electrostatic force that attracts Ca2+ to the negatively charged surfaces, the suppressive effects on osteoclasts proliferation on the positively charged surfaces may enhance bone formation.

Animals↗
PubMed1999

Guided bone regeneration with barrier membranes--a clinical and radiographic follow-up study after 24 months.

The present follow-up study evaluated clinical and radiographic parameters of dental implants placed with simultaneous guided bone regeneration with expanded polytetrafluoroethylene (e-PTFE) membranes. All implants were functioning well 24 months after insertion. In all, 63 patients with a total of 91 e-PTFE-augmented implants were integrated in a regular maintenance protocol. Modified periodontal data of 85 implants in 59 patients were recorded at 24 months and indicated no difference to implants placed in sufficient pristine bone. The mean plaque score (mplI) was 0.29, 74% of the sites showed no plaque. The sulcular probing depth ranged from 1 to 7 mm with a mean of 2.6 mm (SD +/- 0.8). Of the sites 96.5% were < or = 4 mm deep, in 49% of them probing resulted in bleeding. Periotest values 6 and 24 months (mean: -3.4 and -3.4) after placement revealed stable peri-implant conditions and sustained osseointegration. The radiographic evaluation performed 6, 12 and 24 months post insertion yielded a mean bone loss of 0.93, 1.36 and 1.51 mm ranging from 0 to 4 mm. The short-term results of our clinical study demonstrated stable peri-implant conditions 2 years after membrane-protected osseous regeneration. The newly formed bone seemed to be able to withstand functional loading in a predictable manner after 18 months.

Adult↗
PubMed1997

Guided bone regeneration around dental implants in the atrophic alveolar ridge using a bioresorbable barrier. An experimental study in the monkey.

The aim of this study was to evaluate guided bone regeneration (GBR) around dental implants placed in atrophic alveolar ridges using an experimental, nonporous bioresorbable barrier. In 8 Rhesus monkeys, the maxillary canines and lateral incisors were extracted bilaterally and the remaining alveoli were reduced to create atrophic ridges. After a healing period of 3 months, soft tissue expansion was performed using a subperiosteal tissue expander. After 1 month of tissue expansion, and IMZ implant was placed in the atrophic ridge on each side in such a way that its coronal 4 mm to 5 mm remained circumferentially exposed above the bone level. The test implants were covered with a bioresorbable barrier made of poly (D,L-lactid-co-trimethylencarbonate) in a 70/30 ratio, whereas the control implants were covered with a nonresorbable expanded polytetrafluoroethylene (e-PTFE) barrier. The e-PTFE barriers were stabilized with titanium minipins while the bioresorbable barriers were analogously fixed using bioresorbable minipins made of poly (L-lactid-co-D,L-lactid) 70/30. Clinical healing progressed uneventfully in both groups and no soft tissue dehiscences occurred. Histometric and histomorphometric analyses were performed 5 months post surgery. Both test and control implants exhibited direct bone-to-implant contact to variable extents. The mean direct mineralized bone-to-implant contact length fraction was 32% of the total implant length in the test sites and 58% in the control sites. Control sites exhibited significantly greater bone fill compared to the experimental sites (P < 0.001). Histologic observations of test specimens demonstrated a moderate inflammatory reaction related to the degradation and resorption products of the barrier. In conclusion, the nonresorbable e-PTFE GBR barrier was found to be superior to the bioresorbable barriers tested in the present investigation.

Alveolar Bone Loss↗
PubMed1998

Hydroxyapatite fiber reinforced poly(alpha-hydroxy ester) foams for bone regeneration.

A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manufactured using a polymer:fiber weight ratio of 7:6. In contrast, high-porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.

Biocompatible Materials↗
PubMed1999

Maintenance of soft tissue closure following guided bone regeneration: technical considerations and report of 723 cases.

The purpose of this paper is to present simple clinical techniques which have been utilized in a significant number of consecutive cases to maintain primary closure throughout the course of regeneration. The maintenance of soft tissue primary closure following guided bone regeneration (GBR) therapy, while considered a considerable challenge, is recognized as contributing to the maximization of therapeutic results. A retrospective analysis of the maintenance of such soft tissue primary closure following the utilization of specific mucoperiosteal flap designs during GBR surgery in 723 consecutively treated cases was carried out. Soft tissue closure was maintained over the membranes for the course of regeneration (a minimum of 6 months) in 695 cases (96.1%). The maintenance of soft tissue primary closure following GBR therapy may be predictably attained through proper surgical planning, technical care, and appropriate postoperative management.

Adult↗
PubMed2002

Enamel matrix derivative and bone healing after guided bone regeneration in dehiscence-type defects around implants. A histomorphometric study in dogs.

BACKGROUND: The goal of this investigation was to histometrically evaluate the effect of enamel matrix derivative (EMD) on bone healing after guided bone regeneration (GBR) in dehiscence-type osseous defects around dental implants; i.e., in the absence of periodontal ligament cells. METHODS: Six mongrel dogs were used. The second, third, and fourth mandibular premolars (p2, p3, and p4) and first molars (ml) were extracted. After 3 months, 2 implant osteotomies were prepared in each side of the mandible, dehiscence-type defects were created on the buccal aspect of each implant osteotomy (3.5 mm x 5.0 mm), and titanium implants were placed (3.75 mm x 8.5 mm). The surgically-created defects were randomly assigned to one of the treatments: EMD, GBR, EMD+GBR, or control. After 2 months, 4 additional defects were created and treated. The animals were sacrificed 3 months after the placement of the first implants, thus allowing the healing periods of 1 and 3 months. Undecalcified sections were obtained for the histometric evaluation including the percentage of bone-to-implant contact and new bone area on the implant threads related to the defect. RESULTS: No statistically significant differences were observed among the groups in the evaluated parameters after 1 month of healing. After 3 months, no statistically significant differences were observed among the groups for the percentage of bone-to-implant contact. The values for the new bone area were: 55.5+/-11.8, 53.8+/-16.3, 62.1+/-18.4, and 36.9+/-25.1 for EMD, GBR, EMD+GBR, and control, respectively. The difference between EMD+GBR and control was statistically significant (P <0.05). CONCLUSIONS: Within the limits of this study, it can be concluded that EMD may positively influence bone healing after GBR around titanium implants. EMD alone, however, had no statistically significant effect.

Alveolar Bone Loss↗
PubMed2006

Long wave ultrasound may enhance bone regeneration by altering OPG/RANKL ratio in human osteoblast-like cells.

Human osteoblast cell line (MG63) cells were treated with long wave (45 kHz, intensity 30 mW/cm(2)) continuous ultrasound (US) for 5 min and incubated for various time periods following the treatment. The reverse transcriptase polymerase chain reaction (RT-PCR) technique was used for observing the genetic expression and real-time PCR for quantitative analysis of receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG) along with alkaline phosphatase (ALP), an early bone marker, and osteocalcin (OCN) a late marker. ELISA was performed to estimate the amount of the cytokine released into the culture media. The osteoblasts responded to US by significantly upregulating both the OPG mRNA and protein levels. There was no RANKL mRNA expression observed in both the US and control groups and the protein levels were also very low in both groups. There was also no TNF-alpha expression and the TNF-alpha protein levels were insignificant. ALP and OCN mRNA were significantly upregulated in the US group. To our knowledge, this is the first study that shows the effect of US on OPG, RANKL and TNF-alpha expression. US appears to upregulate OPG and may downregulate RANKL production. From these findings, we conclude that therapeutic ultrasound may increase bone regeneration by altering the OPG/RANKL ratio in the bone microenvironment.

Alkaline Phosphatase↗
PubMed2005

[The value of methods of bone regeneration evaluation in limb lengthening by the Wagner, Ilizarov methods and by physeal distraction].

Limb lengthening is a long-lasting process, and during new bone formation different complications may occur. Due to this, early diagnosis of disturbances of new bone formation leading to such complications is of importance. The goal of this study is to analyze already used methods of regenerate evaluation. Material consists of retrospective data of 237 patients, who underwent limb lengthening between 1983 and 2002 by one of three methods: Wagner method, Ilizarow method and physeal distraction. During femoral lengthening by Wagner method appropriate shape of regenerate according to Hamanishi was observed in 9 cases (29.0%), and during tibia lengthening--only in 1 case (6.7%). During femoral lengthening by physeal distraction appropriate shape of regenerate (A or B according to Hamanishi) was observed in 24 cases (77.4%), and during tibia lengthening--in 11 cases (78.6%). During femoral lengthening by Ilizarow method appropriate shape of regenerate was observed in 51 cases (72.9%), and during tibia lengthening--in 46 cases (66.7%). Only in Wagner method a correlation between abnormal regenerate shape and bone consolidation complications was noted. Methods of evaluation of bone regeneration during distraction osteogenesis give only descriptive assessment. So far parameters applied for evaluation of distraction osteogenesis in Ilizarow method and physeal distraction do not allow for detailed assessment of bone regeneration process.

Adolescent↗
PubMed2006

Bioactive glass nanofiber-collagen nanocomposite as a novel bone regeneration matrix.

Nanoscale organized organic-inorganic nanocomposite systems have great potential in the development of biomaterials with advanced properties. Herein, we developed a novel nanocomposite biomaterial consisting of bioactive glass nanofiber (BGNF) and collagen reconstituted fibrous matrix for bone regenerative medicine. A sol-gel derived glass with a bioactive composition (58SiO(2). 38CaO.4P(2)O(5)) was electrospun to a nanoscale fiber with an average diameter of approximately 320 nm. The BGNF was subsequently hybridized with type I collagen, which is the main organic constituent of bone matrix. The BGNF and self-assembled collagen sol were combined in aqueous solution, and then crosslinked to produce a BGNF-collagen nanocomposite, in the form of either a thin membrane or a macroporous scaffold, by adopting appropriate processing conditions. The BGNF was observed to be distributed uniformly within the collagen reconstituted nanofibrous matrix. The nanocomposite matrices induced rapid formation of bone-like apatite minerals on their surfaces when incubated in a simulated body fluid, exhibiting excellent bioactivity in vitro. Osteoblastic cells showed favorable growth on the BGNF-collagen nanocomposite. In particular, the alkaline phosphatase activity of the cells on the nanocomposite was significantly higher than that on the collagen. This novel BGNF-collagen nanocomposite is believed to have significant potential in bone regeneration and tissue engineering applications.

Biocompatible Materials↗
PubMed1993

Localized ridge augmentation using guided bone regeneration. 1. Surgical procedure in the maxilla.

A new surgical technique for localized ridge augmentation prior to the placement of dental implants has been developed. The technique is based on the principle of guided bone regeneration utilizing barrier membranes. In the present article, the currently used surgical procedure is presented through two case reports. In addition, the different aspects of the surgical technique needed to achieve a predictable success are discussed.

Adolescent↗