Trueness of full-arch IO scans estimated based on 3D translational and rotational deviations of single teeth—an in vitro study

Abstract

Objectives To three-dimensionally evaluate deviations of full-arch intraoral (IO) scans from reference desktop scans in terms of translations and rotations of individual teeth and different types of (mal)occlusion. Materials and methods Three resin model pairs reflecting different tooth (mal)positions were mounted in the phantom head of a dental simulation unit and scanned by three dentists and three non-graduate investigators using a confocal laser IO scanner (Trios 3®). The tooth-crown surfaces of the IO scans and reference scans were superimposed by means of best-fit alignment. A novel method comprising the measurement of individual tooth positions was used to determine the deviations of each tooth in the six degrees of freedom, i.e., in terms of 3D translation and rotation. Deviations between IO and reference scans, among tooth-(mal)position models, and between dentists and non-graduate investigators were analyzed using linear mixed-effects models. Results The overall translational deviations of individual teeth on the IO scans were 76, 32, and 58 µm in the lingual, mesial, and intrusive directions, respectively, resulting in a total displacement of 114 µm. Corresponding rotational deviations were 0.58° buccal tipping, 0.04° mesial tipping, and 0.14° distorotation leading to a combined rotation of 0.78°. These deviations were the smallest for the dental arches with anterior crowding, followed by those with spacing and those with good alignment (p < 0.05). Results were independent of the operator’s level of education. Conclusions Compared to reference desktop scans, individual teeth on full-arch IO scans showed high trueness with total translational and rotational deviations < 115 µm and < 0.80°, respectively. Clinical relevance Available confocal laser IO scanners appear sufficiently accurate for diagnostic and therapeutic orthodontic applications. Results indicate that full-arch IO scanning can be delegated to non-graduate dental staff members.

Factors Affecting Trueness of Intraoral Scans: An Update

“…Furthermore, the operator's experience with IOS has also been found to be directly proportional to IOS trueness [22]. The operator's educational level, however, is suggested not to be a factor affecting IOS trueness, as similar results were reported for dentists and dental students [21]. This can be considered evidence of the usefulness of IOS and digital dentistry in dental education [29].…”

“…After initial screening of the publications using titles, abstracts and keywords, 13 articles were considered within the inclusion criteria. After the application of exclusion criteria, a total of nine studies (6 in vitro and 3 in vivo) were finally identified (Figure 1) as eligible to be discussed [19][20][21][22][23][24][25][26][27]. All papers assessed were available on both databases used in this study.…”

Unified protocol to evaluate intraoral scanner resolution, trueness and precision: the RTP-protocol

“…Then, it is possible to build a 3D mesh, i.e., a set of faces whose vertices are the measured points and to project on it the image in order to get a three-dimensional representation of the teeth structure. Over the years, various applications of this data acquisition system have been developed in different aspects of dentistry, such as orthodontics or prosthodontics treatments [2][3][4][5][6]. The performance of an IOS for optical impressions in fixed prostheses has been widely studied in recent years.…”