Abstract
OBJECTIVES: To compare the 5-year outcomes in patients with congenitally missing maxillary lateral incisors (MLIs) rehabilitated with two different narrow-diameter implants (NDIs). MATERIALS AND METHODS: One-hundred patients rehabilitated with a cement-retained bi-layered zirconia single-unit crown on either a Ø2.9 mm (Test) (n = 50) or a Ø3.3 mm (Control) (n = 50) (T1) were assessed at 1-, 3-, and 5-year follow-up (T2, T3, T4). Clinical, radiographic, patient-reported outcome measures (PROMs), biological/technical complications, and esthetic ones were recorded. After the acquisition of intraoral optical scans (IOS) (T4), three different soft tissue profilometric profiles (linear, concave, and convex) were identified. RESULTS: At T4, 66 patients (n = 33 per group; drop-outs n = 33; implant survival rate: 99%; early implant loss n = 1) were evaluated. Between T1 and T4, crestal bone level (CBL) changes at Ø3.3 and at Ø2.9 mm implants were comparable (difference: 0.24 mm; p > 0.05). Despite the positive recorded esthetic scores (i.e., Score 1-2), at T4, 9.1% of Ø2.9 mm versus 18.2% of Ø3.3 mm implants displayed alveolar process deficiency (Score 3). The frequency of soft tissue profilometric profiles was linear (21.2% vs. 40.6%), concave (72.7% vs. 37.5%) and convex (6.1% vs. 21.9%) (Ø2.9 mm vs. Ø3.3 mm group [p > 0.01]). Complications included decementation, ceramic chipping of the incisal edge (3× each), abutment loosening (1×) and a buccal fistula (3×). The statistically significant improved PROMs values at T1 remained stable up to T4 for both groups (p > 0.05). CONCLUSION: The use of Ø2.9 or Ø3.3 mm implants showed comparable positive long-term results. Clinicians can rely on both implant types to replace congenitally missing MLIs.