Peri-implant soft tissue health in relation to depth of implants

Abstract

Positioning the implant-abutment interface deeper than 3mm apical to the buccal gingival zenith is frequently observed in the clinical setting. While histological evidence from animal studies has shown that deeper implants exhibited greater biologic widths with greater ratios of junctional epithelium to connective tissue attachment that may impede the effectiveness of oral hygiene practices, there is a lack of evidence from human trials. The objective of this clinical study is to evaluate peri-implant soft tissue health in relation to the depth of implants by evaluating peri-implant inflammation levels. Sixteen subjects with Straumann Bone Level Tapered SLActive Roxolid implants were divided into deep (>3mm) and shallow (≤3mm) groups by digitally measuring the distance from the implant platform to the buccal gingival margin. Peri-implant soft tissue health was evaluated clinically by measuring probing depths, modified plaque indices, and gingival indices. Pro-inflammatory cytokine levels (IL-1β and TNF-α) were measured by collecting peri-implant crevicular fluid via paper strips and performing laboratory analysis. Multiplex protein analysis was performed by the Multiplex Core Facility at ADA Forsyth (Cambridge, MA). Differences between deep and shallow groups were assessed with the Mann–Whitney U test. Probing depths, modified plaque indices, and gingival indices exhibited no statistically significant difference between the two test groups (P > 0.05). Both pro-inflammatory cytokines (IL-1β and TNF-α) showed no statistically significant difference between the two groups (P > 0.05). However, a trend was observed in the data where the deep group demonstrated higher values across IL-1β levels, modified plaque indices, and modified gingival indices. The depth of implants relative to the peri-implant soft tissue margin is expected to be a critical factor in the ability to resolve peri-implant mucositis and effectively prevent peri-implantitis. The results did not mirror those of similar studies on natural teeth, namely that the effectiveness of oral hygiene practices around teeth decreases as pocket depth increases. However, the trend observed in the data may be a starting point for future controlled clinical trials for more evidence that may help both patients and clinicians with better long-term maintenance of dental implants.