Immediate Placement of Implants into Periodontally Infected Sites in Dogs. Part 2: A Fluorescence Microscopy Study

Purpose: Polychromatic sequence labeling of bone was used to study the effect of periodontal infection on the immediate placement of Frialit-2 implants. Materials and Methods: In the surgical first phase, periodontitis was induced with ligatures involving the mandibular premolars of 5 mongrel dogs, and the contralateral teeth were used as controls (received only prophylaxis). After 3 months, the second phase was initiated and 40 implants were placed in the alveoli of both experimental and control teeth. During the healing period, fluorescent bone markers were injected to study bone formation around the implants. The dyes were injected in the following sequence: oxytetracycline hydrochloride at 3 days after implant placement, calcein green 4 weeks after implant placement, oxytetracycline 8 weeks after implant placement, and alizarin red S 3 days before sacrifice. Following a healing period of 12 weeks, the animals were euthanized and the hemimandibles were removed, dissected, fixed, and prepared for histomorphometic analysis of the percentage of each bone marker present. Results: Fluorescence microscopy showed a similar sequence of bone remodeling (Mann-Whitney test) for both groups: experimental group, 9% bone formation at 3 days, 29% at 4 weeks, 21.6% at 8 weeks, and 52% at 12 weeks; control group, 14% at 3 days, 35.2% at 4 weeks, 32.3% at 8 weeks, and 45.8% at 12 weeks. Discussion: Remodeling in both groups had similar characteristics in the degree of bone formation. Conclusions: It was concluded that periodontal disease does not affect bone remodeling around immediate implants. Although the healing in periodontally infected sites was slower initially, it reached the levels of the non-diseased sites after 12 weeks.