Objectives: To compare the ability of SureSmileTM, InsigniaTM and InvisalignTM to achieve predicted intra-arch tooth positions and further compare their objective grading scores for alignment/rotations, marginal ridge relationships and buccolingual inclination.
Materials and methods: The study was a prospective clinical trial of 145 arches from 44 females and 29 males (54 SureSmileTM arches, 35 InsigniaTM arches, and 56 InvisalignTM arches). All arches were treated by a non-extraction approach and had ≤7 mm of crowding and 45° of tooth rotation. The manufacturer’s recommendations were followed for each group and the final scans were acquired before refinements, rebonding, or wire bending. The virtual set-ups were superimposed on the final scans and the coordinates of 34 landmarks per arch were compared. One hundred and twenty-six end-of-participation arches were suitable for 3D printing and were compared using the American Board of Orthodontics Objective Grading Scores (OGS) for alignment/ rotations, marginal ridge relationships, and buccolingual inclination.
Results: No statistically significant differences were identified in the mean deviation between the target and achieved the position of the anterior landmarks within the treatment groups. The exception was the Suresmile group which had greater vertical discrepancies in the position of the labial CEJ. Although the mean differences between the target and achieved anterior landmark positions for all groups were under 0.5 mm, the range of maximum discrepancy was between 0.7 mm and 4.1 mm. The InsigniaTM system showed significantly greater deviation in upper posterior landmark positions in the transverse and sagittal dimensions, and lower posterior landmarks in the transverse dimension. However, this was due to the InsigniaTM initial set-ups being wider. There was no statistically significant difference between the three systems in combined intra-arch OGS. However, the InvisalignTM system had a significantly poorer alignment/rotation score than the SureSmileTM group. The InsigniaTM system performed better in achieving buccolingual tooth inclination compared to SuresmileTM, and the InvisalignTM system performed better than the SuresmileTM system in the marginal ridge score.
Conclusions: The three systems were comparable in achieving the predicted tooth positions of the anterior teeth in non-extraction, mild-to-moderate, crowded cases. Large discrepancies requiring operator intervention were common within the three systems. Although the three systems had no statistically significant difference in overall intra-arch OGS scores, there were significant differences in the score components.
