Biomechanically Valid Clear Aligner Therapy for Premolar Extraction Case: A Case Report and Literature Review.

This case report details the successful orthodontic management of an adult female with skeletal Class II malocclusion, protrusive facial profile with perioral muscle tension, and mild crowding using clear aligners following extraction of four first premolars. To address the inherent challenges of "roller-coaster effects," a biomechanically appropriate protocol was implemented including rational case analysis and selection, as well as attachment design, anchorage control, overcorrection strategy, and tooth movement pattern. The treatment process successfully avoided refinements and the "roller-coaster effects," accomplishing the entire therapeutic plan with the initial series of clear aligners. This study demonstrates the individualized biomechanical protocols to bridge discrepancies between virtual treatment predictions and real-world therapeutic efficacy, particularly in premolar extraction cases where uncontrolled tipping threatens predictability.