Effect of Intracrevicular Restoration Margins on Peri-implant Health: Clinical, Biochemical, and Microbiologic Findings Around Esthetic Implants up to 9 Years

Purpose: The aim of the present study was to evaluate longitudinally the stability of a cohort of esthetic implants that had been in function for at least 1 year prior to the baseline examination. Materials and Methods: Sixty-one maxillary anterior ITI implants in 45 systemically healthy patients, supporting single crown restorations, were randomly selected and examined. Clinical, microbiologic, and biochemical parameters were recorded at baseline and again after 3 years. Clinical examination included Plaque Index, Gingival Index, bleeding on probing, probing pocket depth (PPD), distance between implant shoulder and mucosal margin (DIM), and mobility. Dark-field microscopy and immunofluorescence were used to evaluate the bacteria morphotypes and the presence of 5 specific pathogenic bacteria, respectively. Peri-implant crevicular fluid (PICF) was collected at the mesial and distal sites of each implant, and total amounts of 3 biochemical markers were assessed: alkaline phosphatase was measured by using p-nitrophenyl-phosphate as substrate, elastase activity was measured by the use of a low-molecular-weight fluorogenic substrate, and the inhibitor α2-macroglobulin (α2M) was measured by enzyme-linked immunosorbent assay. Results: The only statistically significant differences between baseline and follow-up examination concerned PPD and DIM measurements, which increased slightly. The remainder of the clinical measurements and almost all of the microbiologic and biochemical parameters did not change significantly. Furthermore, no associations were observed between the above results and the number of years that implants had been in function. Discussion and Conclusions: Based on an observation period of 4 to 9 years (mean 6.8 years at the time of the follow-up examination), it can be concluded that in patients with appropriate oral hygiene, the intracrevicular position of the restoration margin does not appear to adversely affect peri-implant health and stability.