Laminated Orthodontic Removable aligner for Molar Uprighting

Objective: Conventional removable orthodontic appliances are commonly used for molar uprighting. However there are concerns as to patient discomfort, hygiene and esthetics. Use of laminated clear aligners with soft internal lining has demonstrated potential for lower stress to the teeth, associated bone, greater patient comfort and longer term force application for tooth movement. The purpose of this study was to evaluate effectiveness of molar uprighting using a. Clear orthodontic aligners laminated with a soft inner liner and b. Conventional uprighting orthodontic appliance.

Methods: A photoelastic model of a dentulous adult maxilla was fabricated using different teeth and bone simulants with first molar tooth #14 missing and mesial tilting of tooth # 15. The photoelastic model was digitally scanned; tooth # 15 digitally up-righted using CAD/CAM technology. Clear polycarbonate laminated aligner with lower modulus polyurethane was fabricated from the modified printed model. The same photoelastic model was used to test the laminated aligner and conventional orthodontic appliance and resulting stresses observed in the field of the polariscope and photographed. Stress data for the two systems was analyzed using a computer graphics program to quantify stress intensity by fringe number counting.

Results: The conventional appliance demonstrated localized tensile stress along the mesial crestal bone and compressive stress along the distal crestal bone of tooth #15. The laminated aligner demonstrated similar stress distribution patterns. Further, the conventional appliance demonstrated stress on the opposing side at the loop region not seen with the laminated aligner.

Conclusion: Both conventional and laminated orthodontic appliances demonstrated similar stress patterns during molar uprighting study. The laminated aligners may have benefits where ease of hygiene, lower risk of allergic reactions, unwanted stress to teeth and bone outside of the region, esthetics and or greater patient comfort are mandated.