Comparative Evaluation of Modified Vacuum-Formed Aligners Versus Conventional Micro-Implant Anchorage in Molar...

This study aimed to compare the efficacy of modified vacuum-formed aligners (clear aligners with three-dimensional digital design) versus conventional micro-implant anchorage in molar intrusion for pre-restorative orthodontic treatment.

A total of 91 patients requiring pre-restorative orthodontic treatment were enrolled from Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Institute of Stomatology, Nanjing University between January 2022 and December 2025. All participants exhibited overeruption of antagonist molars due to long-term absence of mandibular first or second molars, resulting in insufficient space for implant restoration and occlusal plane disturbance, thus requiring molar intrusion prior to prosthetic rehabilitation. Patients were divided into two groups: the aligner group (n = 44, treated with digitally designed clear aligners) and the anchorage group (n = 47, treated with traditional micro-implant anchorage).

The anchorage group achieved significantly greater buccal and palatal intrusion than the aligner group (p < 0.05). Postoperative VAS scores at 24 h and 3 days in the aligner group were lower than those in the anchorage group (p < 0.05). Both groups showed comparable intrusion of buccal, palatal, mesial, and distal cusps (p > 0.05). The aligner group had a shorter treatment duration (p < 0.05). The complication rate in the aligner group was significantly lower than that in the anchorage group (p < 0.05).

Modified vacuum-formed aligners provided better patient comfort, shorter treatment duration, and fewer complications, whereas micro-implant anchorage demonstrated superior efficiency in molar intrusion. Both techniques achieved satisfactory three-dimensional control, and clinical selection should be based on individual patient needs.