The influence of controlled occlusal overload on peri-implant tissue. part 4: a histologic study in monkeys.

PURPOSE: The purpose of this study was to observe, after removing occlusal trauma and conducting plaque control, possible macroscopic and histologic changes in peri-implant tissue that had deteriorated resulting from experimental peri-implantitis, and to investigate the necessity for treatment procedures for peri-implantitis. MATERIALS AND METHODS: Four monkeys (Macaca fascicularis) in good general health were used in this experiment. Three months after the second premolar and the first molar were extracted from the right mandible, 2 IMZ experimental implants were placed in each monkey. After a 3-month osseointegration period, a second surgery was conducted, followed by making an impression for fabrication of the prosthesis. Excessive occlusal height of the prosthesis was adjusted to 250 microm, and the experiment was continued for 8 weeks after placement of the prosthesis. Three models were created: (1) A superstructure with an excessive occlusal height was used for 8 weeks without any brushing (positive control, model P); (2) after the first 4 weeks with a prosthesis with excessive occlusal height and no brushing, the superstructure was removed and not used for the last 4 weeks while brushing was conducted (experimental model, model E); and (3) for 8 weeks, a prosthesis with an appropriate occlusal height was used with brushing (negative control, model N). RESULTS: When these 3 models were compared with each other, macroscopic findings indicated inflammation only in model P. Mobility of implants was not seen in any model. Histopathologic observations revealed a slight difference between model E and model P in terms of the degree of inflammatory cell infiltration in the connective tissue. DISCUSSION: No difference was found in the degree of bone resorption. Partial tearing was observed at the contact region between epithelial tissue and implant surfaces. CONCLUSIONS: (1) The contact between implants and epithelial or connective tissue is fragile; (2) inflammation and occlusion must be controlled more prudently than in the case of natural teeth; and (3) once peri-implantitis has progressed, the control of occlusion and inflammation is probably not sufficient to promote the healing mechanism.

Osteocalcin, deoxypyridinoline and interleukin-1beta in peri-implant crevicular fluid of patients with peri-implantitis.

The aim of the present study was to analyze the levels of osteocalcin, deoxypyridinoline (Dpd) and interleukin-1beta as markers of bone metabolism in peri-implant crevicular fluid (PICF) from peri-implantitis patients. PICF was sampled from a total of 34 endosseous titanium implants from 16 patients; nine females (mean age 52.8, range 40-62 years) and seven males (mean age 56.0, range 36-66 years). The implants had been in place for a period of 9-112 months (mean; 35.8 months) since the loading. These sites were categorized as six peri-implantitis, eight peri-implant mucositis and 20 healthy implant. PICF volume from peri-implantitis sites was significantly higher than mucositis and healthy implant sites (P < 0.01). Osteocalcin levels in PICF from mucositis sites were significantly higher than healthy implants (P < 0.05), whereas peri-implantitis sites were not significantly different from either mucositis or healthy implant sites. Dpd could not be detected in any of the samples examined. IL-1beta levels in PICF from peri-implantitis sites were significantly higher than levels from peri-implant mucositis (P < 0.05) and healthy implant sites (P < 0.01). In conclusion, osteocalcin in PICF may reflect increased local bone turnover around implants. Further, IL-1beta should be a useful marker for peri-implant inflammation.