In vivo Response to Sol-Gel and Conventional Bioactive Glasses Placed in Extraction Sockets

A clinical limitation in implant dentistry is loss of alveolar bone following tooth removal, leaving insufficient quantity of bone for esthetic placement of implants. Last year, we reported on the use of sol-gel synthesis methods to create bioactive glasses for use as adjuncts in the treatment of osseous defects. Objectives: This investigation compared and characterized the in-vivo osteoconductivity response elicited by sol-gel derived glass with that invoked by conventionally prepared bioactive glass. Methods: Following removal of the three premolars on each side of the mandible in seven beagle dogs, two extraction sockets were grafted, using either conventional melt-derived bioactive glass, Perioglass™ or experimental sol-gel glass. The third site on each side of the mandible was a non-grafted control site. Animals were sacrificed at 3, 9 and 15 weeks post-surgery. Jaws were embedded and serially-sectioned through the socket regions. Back-scattered SEM (combined with GIS software) was used to determine calcification differences and assess the quantity and quality of new bone; light microscopy (in conjunction with NIH image) was used to distinguish soft tissue type and perform standard histomorphometric analyses to provide area fraction data. Analysis of variance with a three-factor nested-design was used to determine relationships between the three conditions. Results: Mineralized tissue area fractions and calcification extent were not significantly different among any of the conditions at any of the time-points. Osteoid area fraction, however, increased significantly (p<.05) with time of healing in glass-grafted sites, but only marginally in control sites. No quantitative differences were observed between the two glass types. Conclusions: Grafting of sockets with these glasses, although it did not result in more bone present within the 15-week time-span, demonstrated a significant enhancement of bone cell conduction into the socket. Maturation of this tissue will ultimately result in greater bone volume in these grafted sites versus control sites.