Immediate implant placement using a digital surgical guide with hydroxyapatite nano-coated versus uncoated implants: 1-year results of a single-blind randomized controlled trial.

PURPOSE: The primary purpose of this study was to compare 1-year implant success rates between hydroxyapatite (HA) nano-coated implants and uncoated sandblasted, large-grit, acid-etched (SLA) implants placed with a digital surgical guide in the posterior maxilla. Secondary aims were to evaluate peri-implant clinical parameters, placement accuracy, emergence angle, and the influence of abutment height.

METHODS

Twenty-four implants in 19 patients in the HA nano-coated group and 26 implants in 18 patients in the uncoated group were placed flaplessly using digital surgical guides. Outcomes included implant success, probing depth, mucosal recession, keratinized mucosa, vestibular depth, modified plaque index, modified sulcular bleeding index, marginal bone levels (MBLs), implant placement accuracy, and abutment height. Linear mixed-effects models included guide type and implant surface as fixed effects and patient as a random intercept; guide type was categorized as tooth-supported or free-end extension. Regression analyses were used to assess associations between abutment height and emergence angle.

RESULTS

At 1 year, implant success did not differ significantly between groups. Clinical indices and MBLs remained stable. Most emergence angles were <30°. In unadjusted comparisons, several deviations from the planned implant position were smaller in the HA nano-coated group. However, in mixed-effects models, guide type was the principal determinant of deviation, with tooth-supported guides showing smaller deviations than free-end extension guides. Abutment height was negatively correlated with emergence angle, and an abutment height of approximately 2 mm was associated with an emergence angle of approximately 30°.

CONCLUSIONS

At 1 year, HA nano-coated and uncoated SLA implants showed comparable clinical and radiographic outcomes after immediate placement in the posterior maxilla. HA nano-coating provided no measurable benefit, possibly due to a ceiling effect of contemporary SLA surfaces. Digital guide to ensure sufficient abutment height and implant depth may help maintain emergence angles ≤30° and support peri-implant tissue health.

TRIAL REGISTRATION: Clinical Research Information Service (CRIS) Identifier: KCT0006364.