Ultrasonographic Tissue Perfusion in Peri-implant Health and Disease

Abstract

Color flow ultrasonography has played a crucial role in medicine for its ability to assess dynamic tissue perfusion and blood flow variations as an indicator of a pathologic condition. While this feature of ultrasound is routinely employed in various medical fields, its intraoral application for the assessment of tissue perfusion at diseased versus healthy dental implants has never been explored. We tested the hypothesis that quantified tissue perfusion of power Doppler ultrasonography correlates with the clinically assessed inflammation of dental implants. Specifically, we designed a discordant-matched case-control study in which patients with nonadjacent dental implants with different clinical diagnoses (healthy, peri-implant mucositis, or peri-implantitis) were scanned and analyzed with real-time ultrasonography. Forty-two posterior implants in 21 patients were included. Ultrasound scans were obtained at the implant regions of midbuccal, mesial/distal (averaged as interproximal), and transverse to compute the velocity- and power-weighted color pixel density from color velocity (CV) and color power (CP), respectively. Linear mixed effect models were then used to assess the relationship between the clinical diagnoses and ultrasound CV and CP. Overall, the results strongly suggested that ultrasound's quantified CV and CP directly correlate with the clinical diagnosis of dental implants at health, peri-implant mucositis, and peri-implantitis. This study showed for the first time that ultrasound color flow can be applicable in the diagnosis of peri-implant disease and can act as a valuable tool for evaluating the degree of clinical inflammation at implant sites.

Keywords: blood flow velocity; dental implant; evidence-based dentistry; peri-implant disease; peri-implantitis; ultrasonography.

Figure 1.

The ultrasound setup in this study (top) and an example of an implant with peri-implantitis as viewed in different ultrasound scans (bottom). (A) The Mindray dental ultrasound machine. (B) Front view of the miniature probe prototype (L30-8) prior to preparation. (C) Front and (D) lateral views of the probe prototype after preparation for clinical intraoral use. (E) An example of the application of the ultrasound probe at the time of acquiring an image. Note that an anterior site is selected for demonstration purposes. The bottom series of images present (F) the clinical image of an implant with peri-implantitis and its (G) midbuccal, (H) mesial, (I) distal, and (J) transverse ultrasound B-mode scans. Abt, implant abutment; C, crown; CB, crestal bone; DP, distal papilla; I, implant; MP, mesial papilla; mpC, mesial portion of crown; PL, peri-implant lesion; ST, soft tissue.

Figure 2.

Representations of the ultrasound imaging modes (B-mode, color velocity, color power) and the 4 implant regions of dental implants in each clinical diagnosis group. The displayed color velocity visualizes the velocity (speed) at which blood flows, while color power shows the amount of blood flowing within the ultrasound beam in field of view. Color velocity imaging was performed with a constant velocity scale (±2.3 cm/s), with red indicating blood flow toward the transducer and blue denoting blood flow in the opposite direction. Color power is displayed in a single hue of red.

Figure 3.

Ultrasound color velocity and color power of a patient who contributed 2 symmetrical dental implants with different clinical diagnoses. The ultrasound imaging modalities employed in this study, alongside the clinical and 2-dimensional radiographic representation of the dental implants, are shown for the 4 peri-implant regions. Note that for the midbuccal, mesial, and distal scans, the ultrasound probe was oriented parallel to the long axis of the implant and perpendicular to the occlusal plane, while for the transverse scan, the probe was oriented parallel to the occlusal plane. The video file of this figure is available as Appendix Video 1.

Figure 4.

Box plots visualizing the quantified color velocity (left) and color power (right) measures per implant region and clinical diagnosis. Diamond, mean; asterisk, outlier; horizontal line, median; vertical lines, 95% CI. Statistically significant differences based on Akaike information criterion comparisons between pairs of clinical diagnoses are shown with braces and asterisks.