Accuracy of a new, slim, and rigid CAD-CAM transfer tray: An in vivo study

The objective of this study was to evaluate the in vivo transfer accuracy of a new slim and rigid computer-aided design and manufacturing (CAD-CAM) transfer tray.

Seventeen patients (9 males and 8 females; average age, 14.3 years) with permanent dentition undergoing orthodontic treatment were enrolled. Digital models were obtained, and brackets and molar tubes were virtually positioned. The CAD-CAM transfer tray was designed and 3-dimensionally printed, and the bonding procedure was performed. Transfer accuracy was assessed by measuring linear and angular deviations between planned and in vivo bonded bracket positions by superimposition using a local best-fit alignment performed by a semiautomatic algorithm in the analysis software Geomagic Control (3D System Inc, Rock Hill, NC).

A total of 408 teeth (208 maxillary and 200 mandibular) were superimposed. All mean linear deviations were <0.5 mm, although some exceeded the 0.25-mm cutoff (4.4% of mesiodistal measurements, 4.2% of vertical, and 0.2% of buccolingual). Angular discrepancies were greater, especially when using a 1° cutoff (25.7% for torque, 33.8% for rotation, and 18.6% for tip). However, these discrepancies decreased significantly when the cutoff was raised to 2° (in 5.6%, 9.3% and 3.4% respectively). Considering all brackets, no directional bias was detected, except in buccolingual measurements (35% vestibular and 65% lingual). Transfer accuracy was influenced by the variables tooth type, tooth position, and arch, which had various impacts across specific measurements.

The new CAD-CAM transfer tray demonstrated good overall transfer accuracy and some clinical advantages, although refinement of the design is required to enhance its performance.