Trueness comparison of intraoral scans for diverse arch lengths in pediatric dental models.

Background/purpose: Spacing between teeth is a common trait across different stages of dentition. With the tide of the digital impression, the scanning trueness of the intraoral scanner (IOS) is a hot subject. This study aimed to determine the correlation between the level of the spaced dentition and trueness of the intraoral scanning.

Materials and methods: Four arch lengths of deciduous tooth models (spacing Model 1, Model 2, Model 3, Model 4 = 0, 1, 2, 3 mm; maxillary arch length = 73.268, 81.922, 90.776, 97.698 mm; mandibular arch length = 69.092, 76.160, 86.228, 94.344 mm) were designed to measure trueness via an IOS. Statistical analysis included one-way analysis of variance followed by post hoc Tukey tests for comparisons of the data.

Results: The trueness varied across different levels of spacing, with the highest deviation observed between intraoral and desktop scans in Model 3, followed by Model 4, Model 2, and Model 1 in the maxillary arch. In the mandibular arch, the sequence of deviation from highest to lowest was Model 4, Model 3, Model 1, and Model 2. Significant differences were observed among these models in both the maxilla and mandible (P < 0.001).

Conclusion: In both the maxilla (2 mm spacing, arch length ≥81.922 mm) and mandible (3 mm spacing, arch length ≥86.228 mm), scanning accuracy decreases with longer arch lengths. This indicates that as arch length increases, so does the deviation in scanning accuracy. Therefore, the clinician should notice the deviation when using IOSs for the spaced cases.