Evaluation of Endosseous Metal Implant Sites in Rhesus Monkeys: With Special Reference to Fluorescence Microscopy to Study the in vivo Distribution of Newly-Forming Bone

Abstract

Endosseous metal implants were placed in the maxilla and mandible of eight Rhesus monkeys. Following placement, three compounds, tetracycline hydrochloride, 2,4-bis[N,N′-di(carbomethyl)-aminomethyl] fluorescein (DCAF), and Alizarin Red S, were administered i.v. at 3, 7 and 14 days, respectively, in dosages of 25 mg/kg body weight. Following sacrifice, the tissues were fixed in 3% glutaraldehyde and phosphate buffer, embedded in paraplast and undecalcified sections 6–8 μ cut on the Jung's Model “K” microtome. Sections were viewed under a fluorescent microscope (Fluorolume) at 365 mμ equipped with a Schott BG-12 exciter filter and a Schott GG-9 yellow-green barrier filter. Each marker used fluoresced a characteristic color: tetracycline, a golden yellow; DCAF, a bright green; and Alizarin Red S, an orange-red. The healing pattern of bone associated with the implant crypt followed a predictable series of events. The fluorescent distribution of the vital dyes illustrated the sequential stages of healing at 3 days, 1 week, and 2 weeks postoperatively. The initial osseous repair to metal implantation was most prominent in the crypt base as well as along the endosteal lingual or palatal cortex. Early activity was noted in adjacent bony areas referred to as extra-alveolar sites, such as the roof of the mandibular canal and floor of the maxillary sinus. Healing was, in general, advanced at 3 weeks. However, crypt tissue still assumed a remodeling configuration. Fluorescent activity was recorded in new bone completing trabecular development in the spongiosa by centripetal closure of the defect. The concentration of the vital fluorophors used in the investigation apparently had no discernable effect on the rapidity of the healing process.