Abstract:

Objective This work aims to observe the healing of periimplant mucosal tissue injury in beagle dogs after subgingival retraction cord placement by examining the gingival index (GI), quantity of gingival crevicular fluid (GCF), and the proinflammatory cytokine in the GCF. Methods In eight beagle dogs, the fourth mandibular premolars on the left side were extracted (n=8); after two months of healing, bone-level implants were installed. A plaque control regimen was performed throughout the duration of the experiment. After three months, retraction cords were placed subgingivally for 5 min before the cement-retained implant-supported crowns were cemented. GI, GCF quantity, and levels of tumor necrosis factor-alpha (TNF-α) in GCF were assessed before application and on days 1, 3, 7, 14, 28, and 56 after application. Results GI, quantity of GCF, and TNF-α were significantly increased on days 1, 3, and 7 compared with those at the baseline and on days 14, 28, and 56 (P<0.05), and no statistically significant differences were observed among those on days 14, 28, and 56 and the baseline (P>0.05). Conclusion Under the circumstances of good oral hygiene, acute injury caused by placing retraction cord subgin-givally in periimplant mucosal tissue of bone-level implant is reversible. GI, the quantity of GCF, and TNF-α on day 14 return to the baseline levels.

Key words: gingival retraction, periimplant mucosal tissue, gingival index, gingival crevicular fluid, tumor necrosis factor-α