Preformed hydroxylapatite blocks for palatal grafting in orthognathic surgery

Hydroxylapatite has been used as a bone substitute for ridge augmentation, ridge maintenance and periodontal defects for many years. This is a preliminary report of the use of hydroxylapatite blocks as a grafting material in midpalatal splits in orthognathic surgery. With the advent of hydroxylapatite blocks, the need for autogenous bone grafting will, in most cases, be obviated.     

Use of porous hydroxylapatite blocks for augmentation of atrophic mandibles

A clinical study of the use of porous blocks of hydroxylapatite (Interpore 200) for augmentation of atrophic residual mandibular ridges was performed. Fifteen patients each had three preoperatively customized blocks placed. They were then examined clinically and radiographically for at least 2 years. Six patients had skin-graft vestibuloplasties performed over the blocks 3 months after implantation; dentures were made for 11 of the patients. No clinical or radiographic evidence of migration or resorption of the blocks was found; however, all 15 patients suffered complications. Eleven developed ulcerations over the blocks with persistent exposure, six had suture line dehiscence leading to exposure, two infections occurred, and two patients developed chronic pain in the area of block insertion. The skin graft took only partially in all patients undergoing subsequent vestibuloplasties. To date, 37 of the original 45 blocks have required complete removal. Histologic examination of removed blocks has revealed partial filling of the pores with lamellar bone. The use of blocks of porous hydroxylapatite to reconstruct atrophic residual mandibular ridges was found to have an unacceptably high rate of failure and the ability to sustain an overlying split-thickness skin graft was unpredictable.     

Use of blocks of hydroxylapatite for secondary reconstruction of the orbital floor

Malposition of the globe and failure to fuse images may be the result of orbital trauma. Five patients are reviewed in whom secondary correction of enophthalmos, sunken globe and diplopia was performed by implantation of blocks of dense hydroxylapatite.     

Osseointegration of titanium fixtures in onlay grafting procedures with autogenous bone and hydroxylapatite. An experimental histometric study.

The aim of the present study was to determine the degree of osseointegration of fixtures in different onlay grafting materials. Hydroxylapatite blocks of 2 different pore sizes and free monocortical bone grafts from the iliac crest were inserted in Gijttingen minipigs and fixed with 2 titanium fixtures. The extent of the bone/implant interface area on the fixture surface was determined from histological specimens by morphometric measurements and related to the total thread surface of the fixtures. Fixtures inserted into bone grafts showed the most complete degree of osseointegration, whereas the smallest bone/implant interface area was found with fixtures inserted into those HA blocks with the smaller pore size. There was a significant decrease in the degree of osseointegration between the host bone site and the augmentation material only with the fixtures inserted into the HA blocks of smaller pore size.     

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.     

Augmentation of an atrophic edentulous mandible by interpositional grafting with hydroxylapatite

The clinical use of densely sintered calcium hydroxylapatite as a substitute for autogenous bone in interpositional grafting of an atrophic edentulous mandible is described. Results indicate this material appears to be a successful bone substitute for use in the rebuilding of the atrophic mandible.     

Advanced techniques in bone grafting procedures

Technological advancement in bone grafting procedures using purified proteins or stem cells to induce osteogenesis is a significant contribution to patient care. Patients who would otherwise not have been suitable candidates for major autologous bone grafting procedures can continue to benefit from implant reconstruction, with a less debilitating bone reconstructive procedure.     

Use of collagen tube contained implants of particulate hydroxylapatite for ridge augmentation

A preliminary report on the use of collagen tubes containing particulate hydroxylapatite for alveolar ridge augmentation is presented. The surgical technique is described and the results in 20 patients are discussed.     

Use of collagen tubes for implantation of hydroxylapatite: an experimental study

Collagen tubes were compared with routine injection for placement of hydroxylapatite in mandibular defects. It was found that the collagen film containers were effective in providing easier handling, more effective shaping, and less migration of particles.     

Present status of osseous grafting procedures.

Osseous grafting techniques represent one mode of therapy to manage combination pocket-osseous defects. They have their greatest applicability in the intrabony defect although encouraging results have been noted in furcation and suprabony sites. Like all treatment modalities, their usage is dictated by the therapeutic objectives for specific problems and whether their respective advantages and limitations outweigh other management techniques. They are neither a panacea nor an unproven experimental venture. When properly employed, they are a valuable component of currently accepted therapy. When compared with other treatment approaches, the following relative advantages and limitations have been noted with osseous grafts: Advantages 1. Reconstruct lost periodontium. 2. Idealistic therapeutic objective. 3. Reversal of disease process. 4. Increase tooth support. 5. Enhance esthetics. 6. Improve function. Limitations 1. Additional treatment time. 2. Autograft disadvantages. 3. Availability of graft material. 4. Additional postoperative care. 5. Unique postoperative problems. 6. Variations in repair. 7. Longer post-treatment evaluation interval. 8. Predictability. 9. Greater expense. 10. Multistep therapy common. 11. Vulnerability to recurrence.     

Increasing the articular eminence by the use of blocks of porous coralline hydroxylapatite for treatment of recurrent TMJ dislocation

Surgical operations are performed on some patients with recurrent dislocation of the temporomandibular joint. The surgical procedures applied are usually eminectomy and augmentation of the articular eminence. In this article, a surgical procedure for increasing the articular eminence using coralline porous hydroxylapatite is described. The implant is used as an interpositional bone graft placed into a gap created by an osteotomy of the articular eminence. Meniscoplasty is performed simultaneously as an additional operation. This procedure has been performed on eight TMJ's in five patients who had had severe recurrent dislocation. The immediate and further postoperative results were highly successful and no recurrence of dislocation was observed during this period of time.     

Use of polyglycolic acid mesh to confine particulate hydroxylapatite for augmentation of bone in the rat

A preliminary report of the use of polyglycolic acid (PGA) mesh to contain particulate nonresorbable hydroxylapatite (HA) used for augmentation of bone in rats is presented. PGA mesh tubes, approximately 2 mm in diameter and 5 mm in length, were fabricated, filled with HA, and placed in surgically created subperiosteal pockets against the medial cortex of the tibia in rats. Specimens were obtained at two, six, 12, and 18 weeks. The results showed that when the HA was contained within the PGA mesh, severe displacement of particles was prevented and greater HA augmentation was possible. Absorption of the mesh took place between six and 12 weeks, after which the histologic features were the same as those seen when HA was implanted alone. Grossly, the implants appeared to hold firmly to bone even two weeks after implantation. A new, more efficacious delivery system is proposed for the augmentation of atrophic alveolar ridges using HA contained within PGA mesh tubes.     

Predictable synthetic bone grafting procedures for implant reconstruction: part two

When teeth are missing, the surrounding bone and soft tissue is challenged as a result of the natural resorptive process or from traumatic destruction subsequent to extraction. The diminished structural foundation for prosthetic reconstruction with or without implants can therefore be compromised. Recent technological innovations in computer hardware and software have given clinicians the tools to determine 3-dimensional anatomy, quality, and density of bone, which can aid in the diagnosis and treatment planning for reparative or augmentative grafting procedures. Advanced synthetic bioactive resorbable bone graft (SBRG) materials and innovative surgical techniques have made it possible to predictably alter the defective site to create favorable osseous conditions for implant placement. The synthetically derived, resorbable, cluster-like, hydrophilic, particulate, bone-grafting material, having similar mechanical and chemical properties as the host bone, can provide the means to modify existing bone topography by aggressively overpacking the material for ridge preservation, ridge augmentation, or to enhance the bony site and subsequent prosthetic rehabilitation. Since bone does not bridge in empty spaces, the aggressive overfill, commonly referred to as force mineralization, controls excessive bleeding and eliminates voids. Part 1 of this 2-part series presented evidence of safety and effectiveness of the SBRG materials, crystal morphology, chemical properties, and characterization through animal and clinical studies. The osteoconductive cluster particulate assists in the bridging of lost bone anatomy by chemotactic response and resorption concurrent with regeneration of new bone formations. Part 2 demonstrates specific clinical handling characteristics and use of this material to facilitate implant placement and/or prosthetic reconstruction through clinical case applications. Additionally, in a unique clinical presentation, a composite graft mixture consisting of the SBRG and dense, ceramic, bovine-derived HA (sintered at 1,150 degrees C) was compared using electron microscopy.     

Use of hydroxylapatite/ polymer-composite in facial bone augmentation. An experimental study

On purpose to achieve better and more controlled alveolar ridge augmentation, biodegradable polyglycolide (PGA) curved implants with porous, particulate hydroxylapatite (HA) were developed to be used in an experimental augmentation in sheep mandible. Prior to surgery curved PGA implants were loaded with particulate HA with help of a rather fast degrading adhesive, polyglycolide/polylactide (PGA/PLA) copolymer. This augmentation device was inserted into the ridge using a slight modification of the tunnelling technique. Macroscopically, a dehiscence with loss of HA particles was observed in 3 of the 16 augmentations. Bone ingrowth was seen in a noticeable degree in one sheep at 24 weeks. Instead, foreign body-type cells were shown at the interface of mandibular bone and hydroxylapatite deposit, as well as abundant connective tissue reaction inside HA deposits. The results of the study give rise to concern about bony integration in the presence of biodegradable polyglycolide substances in HA augmentation. The findings call in question even their use as a carrier for bone forming agents in combination with HA.