Objective: To compare the clinical efficacy of angulated screw-retained and cemented single implant crowns(SIC) in esthetic region.

Methods/Design: The study was a prospective, single center, randomized controlled clinical trial. Patients with the needs of single tooth restoration in esthetics region were recruited from Oct. 2018 to Aug. 2019. Sixty patients were enrolled in the present study and they were randomly assigned into two groups: angulated screw-retained group(AG, 30 patients) and cemented group (CG,30 patients). Clinical and radiological evaluations were performed on the day of final crowns delivery and 12 months later. Implant survival rate, marginal bone loss(MBL), pro-inflammatory cytokinesin peri-implant crevicular fluid (PICF)(TNF-α, IL-6), mechanical complications, peri-implant conditions(mPI, PD, BOP%), pink esthetics score/white esthetics score (PES/ WES) and patients satisfaction were assessed.

Inclusion Criteria:

• 1) age≥18;
• 2) Single dental implant in the esthetic region;
• 3) adjacent to natural teeth;
• 4) absence of oral mucosal disease and oral infection;
• 5)implants withconical connection (Nobel Active, Nobel Biocare® or NobelReplace Conical Connection, Nobel Biocare®);
• 6)patients with the willingness of all-ceramic permanent restorations.

Exclusion Criteria:

• 1)Multiple implants in the esthetic region, or the restoration is a bridge;
• 2)Heavy smokers (>10 cigarettes/day);
• 3) the angle between implant axis and restoration axis>25°;
• 4) uncontrolled periodontitis;
• 5) with systematic diseases that may affect implant therapy, such as uncontrolled diabetes mellitus (Fasting blood-glucose>7.2mmol/L, Glycosylated hemoglobin >7%), current intake of bisphosphonates (treatment for malignancy), pregnant(or plan to get pregnant), with history of radiation therapy in head and neck region;
• 6) Unwilling to participate in the present study.