As the trend of miniaturization advances in the industry, micro gears are becoming increasingly crucial across various sectors. They are an integral part of micro-mechanical systems and are used, for example, in medical technology for the kinematic transmission of torque in dental instruments. Simultaneously, the need to control competition-critical acoustic emissions and vibrations during manufacturing sets new quality assurance targets. Findings from extensively studied macro gears are often not applicable to micro gears, which are currently underrepresented in existing standards. Owing to the limitations of existing manufacturing technologies, micro gears typically exhibit significant geometric deviations concerning their structural dimensions, which must be minimized for the quality driven series production of the future. To overcome this deficit, a strategy for adaptive in-line quality control in micro gear manufacturing is presented. The developed approach enables machine-oriented control of quality-critical features by using 100% in-line measurements based on optical focus variation technology. Established on statistical methods, an in-line capable measurement program can be developed with low measurement uncertainty within the cycle time. Additionally, the implementation of near-real-time kinematic rotary path simulation enables more accurate predictions of functional parameters, minimizing uncertainty. The developed approach is validated in an industrial application focusing on serial production for dental instrument manufacturing. The results reveal that it is feasible to adaptively adjust production based on an in-line quality assessment to achieve specifications close to the technological limits. Furthermore, function-oriented parameters are captured at 100%. This approach demonstrates that complex micro gears can be optimized for quality improvement by integrating in-line measurement technology within advanced control loop.