Comprehensive Optical Assessment of Peri-Implant Mucosa

Esthetic outcomes with implants begin with proper implant placement, but the predictability of the peri-implant esthetic outcome is also affected by patient’s pre-existing or reconstructed local tissue. An unpleasant optical phenomenon where the peri-implant mucosa appears gray has been documented in the literature. However, it’s etiology and solutions have not yet been fully investigated. The overall goal of this project is to perform comprehensive optical examination and to establish the clinical guideline to achieve optimal peri-implant mucosa. A. Specific Aim 1: Assess the optical properties of the peri-implant mucosa. A total of 40 patients who has a healthy, single bone level implant in the maxillary anterior zone is recruited at HSDM. For each patient, the test site (peri-implant mucosa) and the control site (adjacent natural gingiva) are identified. Using a dental spectrophotometer, CIELAB color coordinates, translucency parameter (TP), and thickness of test and control site are measured. We found that the color of peri-implant mucosa of bone level implants is significantly different from adjacent gingiva (p=0.0003). We further found that while color of the peri-implant mucosa are significantly different from those of the adjacent gingiva, the thickness and TP do not contribute to this color difference. B. Specific Aim 2: Evaluate the vascular morphology change of the peri-implant mucosa. Studies have shown that a significant vascular reconstruction takes place around a dental implant. Therefore, using a narrow band imaging endoscope, interpapillary capillary loops (IPCL) around a dental implant are compared to those around a natural tooth. We found that there are more interpapillary capillary loops in peri-implant mucosa compared to gingiva (p=0.02). C. Specific Aim 3: Determine the threshold for soft tissue color discernment While many studies have demonstrated the color threshold for shades of teeth and restorations, there is very little information with respect to soft tissue colors. Therefore, in controlled in-vivo and ex-vivo settings, color threshold of soft tissue was investigated, and a correlation between the objective color threshold (ΔE) and subjective color threshold for soft tissue color were also determined. For soft tissue, objective threshold is found to be ΔE=6.50-6.99, and the correlation between subjective and objective evaluations is significant (r=0.67) in ex-vivo setting. D. Specific Aim 4: Evaluate the efficacy of the newly developed colored abutment on improving the optical property. In order to improve this gray optical phenomenon, a pink colored abutment system has been developed. In a randomized manner, we investigated the color of the peri-implant mucosa with pink and gray abutment. We found that this pink colored abutment can significantly improve the aforementioned optical phenomenon, especially in those with thin tissue (<2mm) (p=0.04) and those with pink neck implant (p=0.04). The clinical significance, however, still needs to be determined.