Custom-Made Root Analog Immediate Dental Implants: A Prospective Clinical Study with 1-Year Follow-up

To compare three different types of custom-made root-analog immediate (RAI) dental implants.

Patients with fractured and/or nonrestorable teeth with uncompromised periodontal ligaments were included in the study. The exclusion criteria were as follows: any uncontrolled systemic disease, bruxism, poor oral hygiene, active periodontal disease, and/or chronic marginal periodontitis. CBCT scans of the teeth were taken, and the datasets were used to reconstruct 3D models that were transferred to 3D modeling software to design the RAIs. Group 1 (GR1) consisted of zirconia RAIs manufactured using a computer numerical control (CNC) machine, group 2 (GR2) consisted of titanium RAIs formed by using a CNC machine, and group 3 (GR3) consisted of titanium RAIs manufactured by using direct laser metal sintering (DLMS) technology, all of which were placed immediately after tooth extraction. Primary stability was measured by using Periotest M. Metal-ceramic single crowns were cemented 3 months later. All implants were evaluated clinically and radiologically 1 year after implant placement.

A total of 51 patients (18 men, 33 women) aged between 18 and 66 years (average 34.2 years) were included in the study. In 4 patients, RAIs could not be placed due to the lack of primary stability, and they were excluded. In the remaining 47 patients, the custom-made RAIs (GR1: n = 21, GR2: n = 17, GR3: n = 18, total: n = 56) were placed into fresh extraction sockets immediately after tooth extraction for each patient. Primary stability was achieved. Periotest values (PTV) were between -1.4 and -6.2 (mean -3.3). The mean initial PTV (PTV0) was -2.3 ± 1.8 for the failed implants and -4.5 ± 0.8 for the surviving implants. PTV0 was an independent risk factor (HR 3.61, 95% CI: 1.56-8.35, P = .004) for survival rate, which was 33.3%, 70.6%, and 44.4% for GR1, GR2, and GR3, respectively. The overall survival rate was 48.2%. There was no significant difference between the groups regarding the probability of survival (P = .051). The survival rate was significantly lower for anterior RAIs (P < .001). Clinically healthy gingival margins were observed without any signs of periodontitis or implant mobility, and the mean PTV was -4.0 ± 1.9 in surviving implants, whereas the mean marginal bone loss was 1.3 ± 0.6 mm (median, 0.8; 95% CI: 0.1-3.4) at the 1-year follow-up.

This study was the first attempt to compare different RAI manufacturing techniques and biomaterials in the literature. Although the probability of survival was not statistically significant between the groups, the survival rate in GR2 was higher than in the other two groups. Nevertheless, the overall survival rate was significantly lower (48.2%) than in the previous reports. Primary stability was an independent risk factor for failure. Further studies with the minimized variables between groups should be designed for precise results.