Sanford S. Rothstein

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.

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.

Long-term study of hydroxylapatite implants in canine alveolar bone

Routine light and fluorescence microscopic examination of hydroxylapatite root implants showed that, in general, bone formed above the original superior surface of the ceramic implant on the lingual crest. In the 40 experimental specimens recovered, 30% also showed new bone completely covering the implant, proceeding from the buccal to the lingual area. Sixty per cent of the specimens that exhibited complete osseous covering were the more posteriorly placed implants from the fourth premolar and the first molar areas. Thirty-three per cent of the specimens exhibited bone formation at or over the superior buccal margin of the implant.

Tissue response in dogs to dense hydroxylapatite implantation in the femur

Six and eight years after the implantation of both granular and solid ceramic hydroxylapatite forms in the femurs of beagle dogs, histologic examination demonstrated that the implants were totally encased in dense mature bone. The endosteal and periosteal surfaces appeared normal, and no resorption of the solid implants was observed. However, at six years, a few granules located at the periosteal surface showed interdigitation of connective tissue stalks, with large multinucleated cells at the interface with the implant. This phenomenon may represent some limited resorptive activity on the surfaces of these few isolated granules. Initially, radiographs showed exaggerated degrees of bone deposition on the endosteal surface under the solid implants (discs), as opposed to a less pronounced endosteal response to the implants of particulate material. In some cases, particularly with the disc implants, cracks were found in the ceramic material six years after implantation. These cracks, on staining, were found to be filled with amorphous material, suggesting an osseous matrix. The results of these long-term studies indicate that such hydroxylapatite implants in bone are highly biocompatible. Bone deposition and maturation on the implant surface resulted in a homogeneous bone/implant interface in which the host tissues appeared to respond to the implant as if it were normal bone.

Passive immunization for hepatitis B

Numerous studies have been conducted to assess the effectiveness of gamma globulin in preventing type B hepatitis. These investigations have evaluated the effectivenesses of standard immunoglobulin (IG) and hepatitis B immunoglobulin (HBIG) in pre-exposure and postexposure settings. The current data suggest that HBIG and standard IG containing some antibody to hepatitis B surface antigen may be effective for pre- and postexposure prophylaxis of hepatitis B. It is recommended that HBIG be used for the postexposure prophylaxis of individuals sustaining accidental needle-stick or mucosal exposure to blood known to contain hepatitis B surface antigen. If HBIG is unavailable, then standard IG may be beneficial. While pre-exposure prophylaxis with gamma globulin may be effective, there are appropriate environmental control methods available that may significantly reduce the transmission of hepatitis B, and these should be fully implemented.