American Board of Orthodontics (ABO) Practice Exam

Invisalign is designed to move teeth through a series of custom-made, removable aligners that exert gentle force on the teeth. However, when it comes to molar movement, especially bodily movement, there are inherent limitations due to the biomechanics involved and the physical characteristics of the aligners.

The correct answer indicates that the effectiveness of Invisalign for moving molars is limited to approximately 1.5 mm. This limitation arises because molars are larger teeth with more complex root structures, and they are anchored more firmly in their sockets compared to anterior teeth. The design of the aligners, which relies on a series of small movements, is more effective for the anterior teeth. Additionally, achieving significant molar movement may require additional anchorage or auxiliary devices to help overcome the anchorage loss that typically occurs with aligner treatment.

In contrast, options suggesting that Invisalign can achieve greater bodily movement, such as 3 mm or without limitation, do not take into account the mechanical constraints of using clear aligners specifically on molars. The understanding of these limitations is crucial for clinicians to set realistic treatment goals and expectations when utilizing Invisalign for comprehensive orthodontic therapy.