Microthreaded versus smooth implant collars: A randomized trial on peri-implant inflammatory cytokines and crestal bone levels

AIMS: To evaluate the impact of implant collar design on peri implant inflammatory biomarkers and crestal bone levels over a 6-month period. SETTINGS AND DESIGN: This pragmatic, randomized, parallel-group clinical trial was conducted at the Department of Prosthodontics and Crown and Bridge, Manav Rachna Dental College, between May 2023 and May 2024. MATERIALS AND METHODS: The study included 30 systemically healthy patients aged 20-60 years with a single missing tooth in the mandibular molar region. Patients were randomly assigned to two groups based on the implant collar design - smooth or microthreaded. Implants were placed following a standardized two stage surgical protocol. Peri-implant crevicular fluid was collected at the time of implant placement, 3 months, and 6 months postplacement to assess inflammatory biomarkers (interleukin-1 [IL-1β] and tumor necrosis factor alpha [TNF-α]) using ELISA. Peri-implant crestal bone levels were measured radiographically at the same intervals. STATISTICAL ANALYSIS USED: Statistical analysis was performed using the SPSS (version 21.0). The data were analyzed using appropriate statistical tests. P < 0.05 was considered statistically significant. RESULTS: IL-1β and TNF-α increased in both groups at the 3-month follow-up, reflecting a typical postsurgical inflammatory response and subsequently decreased at 6 months. The changes in cytokine levels were not significantly different (P > 0.05) between groups, suggesting a similar inflammatory response regardless of collar design. Crestal bone levels in implants with microthreaded collar design exhibited significantly lower loss (0.44 mm) compared to smooth collar implants (0.94 mm), with a statistically significant mean difference of 0.5 mm (P = 0.019). Correlation analysis revealed no statistically significant relationships between crestal bone levels and inflammatory markers at any time point. CONCLUSION: Although both collar designs had a limited influence on the early peri-implant inflammatory response, but microthreaded collars were more effective in preserving crestal bone.