Predictors of Infrazygomatic Crest Implant Failure: A Prospective Study on Risk Factors, Stability, and Clinical...

Infrazygomatic crest (IZC) implants are widely used for orthodontic anchorage. However, their success is influenced by multiple factors. This study aimed to evaluate the failure rates of IZCs and identify key predictors, including age, sex, implant placement characteristics, loading protocols, inflammation, mobility, bone density, and oral hygiene. Understanding these factors can help optimize treatment strategies and improve implant survival rates.

This prospective, cross-sectional observational study was conducted at the Department of Orthodontics from August 2022 to December 2024. Sixty patients requiring IZC implants were enrolled, with the systematic exclusion of those with systemic conditions affecting bone metabolism. The implants (Dentos Absoanchor, 12/14 mm length, 2 mm diameter) were placed at an insertion angle of 0-90⁰ under standardized surgical protocols. Bone density was assessed using cone-beam computed tomography (CBCT), and the patients were divided into immediate and delayed loading groups. Implant failure was defined as loss or removal within eight months of placement. Statistical analyses included univariate regression, receiver operating characteristic (ROC) curve analysis, and odds ratio (OR) calculations.

Of 60 implants, 18 (30%) failed. Patients aged > 18 years had a higher failure rate (~35%) than those aged < 18 years (~25%), while females exhibited a greater failure rate than males. Implants placed at 0-45⁰ had a higher failure rate (~40%) than those at 45-90° (~30%). Shorter implants (12 mm) had a failure rate of ~35%, whereas longer implants (14 mm) had a ~25% failure rate. The immediate and delayed loading protocols showed similar failure risks (~30%). Inflammation (~55% risk of failure) and mobility (~90% risk of failure) were the most significant predictors of implant failure. Poor oral hygiene was strongly associated with treatment failure (OR = 0.06). A bone density below 914 Hounsfield units (HU) was linked to higher failure rates, although ROC analysis indicated a moderate predictive ability.

IZC implant failure is multifactorial, with mobility, inflammation, and poor oral hygiene emerging as critical risk factors. Although bone density played a role, implant placement characteristics significantly influenced success. Clinicians should prioritize optimal insertion angles (45-90⁰), longer implants (14 mm), and strict peri-implant hygiene.