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PubMed1985

Compressive strength measurement and microstructure studies of hydroxyapatite cones.

Compressive strength measurement and microstructure studies of standard, diamond bur-ground, and fracture surfaces of durapatite cones were reported. The compressive strength measurements of durapatite cones were variable and strongly dependent on the test method. The fracture force ranged from 1090 to 3692 N and the calculated compressive strengths ranged from 113 (16,333 psi) to 389 mN/m2 (56,462 psi). The outer surface of durapatite cones was rough, irregular, and dense. Sharp fracture lines occurred along the longitudinal axis of the cones. Isolated porosity was seen in the fracture surface of one specimen. Grinding hydroxyapatite cones using a high-speed diamond bur with water spray produced a surface grinding feature, an irregular surface topography, and microcracks. The microcrack directions were perpendicular to the direction of the diamond bur cutting features.

Durapatite↗
PubMed1989

Permeability of apical barriers.

The purpose of this work was to measure the permeability (hydraulic conductance) of root canal apical barriers in vitro. In 30 extracted teeth, the pulp tissue was removed and the apical opening standardized and enlarged using endodontic files. One-millimeter thick barriers of either autogenous dentin chips, calcium hydroxide powder, or durapatite particles were placed just inside the apical opening. The prepared teeth were mounted in a special chamber, fluid pressure applied, and the resultant flow measured. The permeability of dentin chip barriers in 10 additional teeth with nonstandardized apical openings was measured also. The standardized canals with the autogenous dentin chip barriers had a mean permeability of 0.0010 microliter/s/psi at 20 psi applied pressure. Teeth with calcium hydroxide barriers averaged 0.0012 microliter/s/psi. The durapatite particle barriers were much more permeable and averaged 0.0220 microliter/s/psi. It was concluded that this technique is useful in evaluating the effectiveness of apical barrier materials. For the materials tested, autogenous dentin chips and calcium hydroxide barriers have significantly lower permeability than durapatite barriers (p = 0.05).

Calcium Hydroxide↗
PubMed1977

Tissue, cellular and subcellular events at a bone-ceramic hydroxylapatite interface.

A new polycrystalline form of hydroxylapatite, durapatite, has been examined as a cortical bone implant in dogs. Utilizing histological and electron optical techniques, it has been found that durapatite does not elicit a foreign body response and that all new bone surrounding the material is normally calcified. Bone was found to strongly adhere to durapatite and preliminary evidence suggests this bonding may be due to direct chemical attachment of bone to the material.

Animals↗
PubMed1991

An in vivo study of the use of a nonresorbable ceramic hydroxyapatite as an alloplastic graft material in periapical surgery.

This study evaluated reactions to a hydroxyapatite after endodontic treatment and periapical surgery. Thirty-eight root canals in two Macaca speciosa monkeys were endodontically treated. Apicoectomy was then performed, leaving bony defects at the apex of each root. The defects were either packed with Durapatite ceramic crystals or allowed to fill with blood. Each animal received at least one dose of Procion red, a hard-tissue marking agent. After healing periods of 2 to 6 months, the apices were examined clinically, radiographically, and histologically. The ceramic material was well tolerated clinically with no gross evidence of inflammation or rejection. Histologically, the material was biocompatible. Healing of the experimental sites consisted of an initial investment of the apatite crystals in fibrous connective tissue followed by eventual replacement of the connective tissue with bone. Despite its excellent biocompatibility, the material appeared to retard osteogenesis by its physical presence. Although the ceramic eventually became entrapped in bone, without an intervening layer of connective tissue, there was a significantly greater amount of new bone in control sites.

Animals↗
PubMed1984

Use of hydroxylapatite for the augmentation of deficient alveolar ridges.

Investigations were undertaken to evaluate nonresorbable, particulate ceramic hydroxylapatite (durapatite) for augmentation of deficient alveolar ridges. One hundred and fifteen augmentations in both jaws were reported for 110 patients over a 33-month postoperative period. Subjective and objective data show that the implant was successful for all classes of ridges augmented; height, bulk, contour, and ridge form generally improved, and soft tissue overlying the augmented ridges was firm and immobile. Impressions for dentures were usually obtained four to six weeks after surgery, and the dentures were more stable, retentive, and esthetically pleasing than the preoperative prostheses and required fewer relinings. Other than transiently altered sensations resulting from mental nerve manipulation during surgery, patients had few complications. No infection or bone resorption beneath the implant was observed throughout these studies. It was concluded that hydroxylapatite particles placed through a subperiosteal tunnel offer a highly successful method of ridge augmentation and eliminate the most serious problems associated with the use of autogenous or banked bone, namely, morbidity, risk, costliness, and poor results.

Adult↗
PubMed1984

Histologic observation of soft tissue responses to implanted, multifaceted particles and discs of hydroxylapatite.

The effects on soft tissue of short- and long-term implants of ceramic hydroxylapatite (durapatite) are reported. In rats, after one week and one, six, and 12 months of subcutaneous implantation of hydroxylapatite in multifaceted particle and disc form, neither particles nor discs had resulted in any microscopically remarkable inflammation. In beagle dogs, after subcutaneous implantation of hydroxylapatite as multifaceted particles and as discs for seven and 24 days, nine months, and two and six years, no implant migration was observed. Encapsulation of particles and discs of increasing thickness was seen throughout the six years of observation. Except for a few isolated macrophages seen within the connective tissue stroma at seven and 24 days, no evidence of inflammation was found. In tissue sections taken at six months from beagle dogs in which multifaceted particles had been placed subperiosteally beneath the gingiva, dense connective tissue was observed adjacent to and surrounding the individual particles. These results show that hydroxylapatite implanted subcutaneously in rats and dogs produces little or no inflammatory response and is compatible with tissue irrespective of the shape of the implant.

Animals↗
PubMed1991

Effects of calcium-phosphate-based materials on proliferation and alkaline phosphatase activity of newborn rat periosteal cells in vitro.

The effects of dental materials, intended for bone substitution, on cell growth and alkaline phosphatase activity of newborn rat periosteal cells have been studied in vitro. Confluent periosteal cells were exposed to three apatite-based materials (400 micrograms/mL) with different physico-chemical properties. The materials were a beta-tricalcium phosphate with a microporous granular structure obtained by sinterization (Synthograft, Johnson & Johnson, East Windsor, NY), a 40-60-mesh microporous durapatite ceramic (Periograf, Sterling Drug, Inc., Rensselaer, NY), and a 1-2-mm-diameter hydroxyapatite ceramic (Osprovit, Feldmuhle Aktiengeselschaft, Plochingen, Germany) with macropores larger than 100 microns. Cell proliferation and alkaline phosphatase activity were assessed by incorporation of 3H-thymidine into trichloroacetic-acid-precipitable material and by a fluorimetric method, respectively. Cell viability and compatibility with the materials were determined by morphology in phase-contrast microscopy. Periosteal cells showed increased proliferation following exposure to Synthograft, but were unaffected by Osprovit, whereas Periograf caused significantly reduced cell growth. Alkaline phosphatase activity was unaffected by Osprovit, but was decreased by both Synthograft and Periograf. The results indicated a differential response of periosteal cells to bone-substituting materials with heterogeneous physico-chemical characteristics.

Alkaline Phosphatase↗
PubMed1984

Particle size of periodontal bone grafting materials.

Samples of autogenous bone obtained by high speed burs, low speed burs, hand chisels and bone blending; freeze-dried bone purchased from a tissue bank and alloplastic materials, such as Calcitite, Durapatite, Periograf and Synthograft used as donor material for periodontal bone grafting procedures, were evaluated histometrically. Particle sizes ranged from a mean of 210 X 105 mu for bone blend to 1559 X 783 mu for hand-chisel samples. Except for those two materials, all of the others were in the 300 to 500 microns (0.3-0.5 mm) range that seems to be preferred for use in periodontal defects.

Biocompatible Materials↗