INTRODUCTION: To present the 3-year clinical, radiographic, and aesthetic outcomes in patients with congenitally missing lateral incisors rehabilitated with two narrow-diameter implants (NDIs).

METHODS: The original population consisted of 100 patients rehabilitated with a cement-retained bi-layered zirconia single-unit crown supported by either a Ø2.9 mm (Test) or a Ø3.3 mm (Control) NDI (n = 50). At the 1- and 3-year follow-up (T2, T3), implant survival rate, crestal bone level (CBL) changes, biological, and technical complications were recorded, while the assessment of the aesthetic outcomes was performed using the Copenhagen Index Score.

RESULTS: Seventy-four patients Ø2.9 mm (n = 39) or Ø3.3 mm (n = 35) reached T3, as 24 patients were lost to follow-up and 1 implant (Ø3.3 mm) was removed. Throughout the observation period, minimal CBL changes (i.e., <1 mm) were detected between groups. Despite the positive aesthetic scores recorded (i.e., 1-2), at T3 20% of patients rehabilitated with a Ø3.3 mm versus 2.6% of patients Ø2.9 mm displayed an alveolar process deficiency (Score 3). No additional technical and/or mechanical complications were recorded between T2 and T3. Tooth vitality was maintained in all neighboring teeth. Peri-implant probing depths and plaque scores remained low in both groups (p > 0.05).

CONCLUSION: The use of 2.9 or 3.3 diameter implants showed comparable favorable mid-term results in terms of survival rate, CBL, and aesthetic outcomes. Hence, clinicians should rely on the use of such NDIs when replacing maxillary lateral incisors.