Purpose of the study: To determine the influence of the crown-to-implant ratio (C/I ratio) on load distribution, implant stability (ISQ), and the frequency of marginal bone microresorption. Materials and methods: The study included 78 patients who underwent implant-supported restorations after sinus lifting. Cone-beam computed tomography (CBCT) and resonance frequency analysis (RFA) were used to measure implant length, clinical crown height, bone condition, and ISQ values. The C/I ratio was calculated as the ratio of clinical crown height to implant length. Statistical analysis included Pearson correlation and Student’s t-test (p < 0.05). Results: A strong positive correlation was found between an increased C/I ratio (>1.2) and marginal bone microresorption (r = 0.68; p < 0.01), while a negative correlation was observed between C/I and implant stability (r = -0.62; p < 0.01). Conclusion: Maintaining a C/I ratio ≤ 1.1 ensures optimal biomechanical balance, higher implant stability, and reduced risk of bone resorption. Excessive C/I ratios (>1.2) are associated with biomechanical overload and compromised osseointegration.