Objective To compare the differences in thickness and fitting accuracy between direct-printed aligners(DPA)and conventional thermoformed aligners(TFA),and to provide experimental evidence for the clinical application of clear aligners(CAs).Methods Sixteen adult subjects with mild dental crowding and no significant caries or restorations were recruited.For each subject,CAs were fabricated using direct three-dimensional(3D)printing and conventional thermoforming methods.The CA thickness was measured at the labial/buccal and lingual surfaces of incisors,canines,and first molars using a high-precision electronic thickness gauge.Micro-CT scanning was employed to analyze the gap between the CAs and dental models,followed by statistical analyses.Results The overall mean thickness of the DPA group was(0.60±0.04)mm,significantly higher than that of the TFA group(0.48±0.06)mm(P＜0.000 1),with superior thickness uniformity.The average gap between CAs and dental models in the DPA group was(0.29±0.08)mm,significantly smaller than that in the TFA group(0.31±0.16)mm(P＜0.05),particularly at the incisal edges of incisors,buccal surfaces of canines,and occlusal surfaces of first molars.Conclusions Compared to conventional TFA,DPA demonstrates significant advantages in thickness uniformity and fitting accuracy,indicating that DPA has greater application potential in orthodontic clinical treatment.

Objective To compare the differences in thickness and fitting accuracy between direct-printed aligners(DPA)and conventional thermoformed aligners(TFA),and to provide experimental evidence for the clinical application of clear aligners(CAs).Methods Sixteen adult subjects with mild dental crowding and no significant caries or restorations were recruited.For each subject,CAs were fabricated using direct three-dimensional(3D)printing and conventional thermoforming methods.The CA thickness was measured at the labial/buccal and lingual surfaces of incisors,canines,and first molars using a high-precision electronic thickness gauge.Micro-CT scanning was employed to analyze the gap between the CAs and dental models,followed by statistical analyses.Results The overall mean thickness of the DPA group was(0.60±0.04)mm,significantly higher than that of the TFA group(0.48±0.06)mm(P＜0.000 1),with superior thickness uniformity.The average gap between CAs and dental models in the DPA group was(0.29±0.08)mm,significantly smaller than that in the TFA group(0.31±0.16)mm(P＜0.05),particularly at the incisal edges of incisors,buccal surfaces of canines,and occlusal surfaces of first molars.Conclusions Compared to conventional TFA,DPA demonstrates significant advantages in thickness uniformity and fitting accuracy,indicating that DPA has greater application potential in orthodontic clinical treatment.