Validation of a 3D laser scanner for odontometric measurements

Measurement of crown size diameters provides important information in the diagnosis and treatment planning of intra- and inter-arch disharmony. Furthermore, patterning of detailed crown size diameters can be linked to genotype studies to help to understand the aetiology of various dental conditions such as, anomalies of tooth number. 3D methods have recently replaced the manual and 2D methods in odontometric studies. However, it is important to validate any new 3D scanner of study models to provide accurate recordings of tooth dimensions. Objectives: To validate a new 3D laser scanner against the manual method using 3-dimensional measurements. Methods: Two permanent tooth types (the upper right central incisor and the upper left first molar) on 20 randomly selected study models were used to carry out the measurements. These were the mesio-distal (MD), bucco-lingual (BL) and inciso-gingival (IG) or occluso-gingival (OG) dimensions. Each of two operators has carried out the measurements twice 2 weeks apart using the manual and 3D laser scanner. Intra- and inter-operator reliability was assessed using the intra class correlation coefficient (ICC). Results: The inter-operator reliability for all variables ranged from 0.77-0.90 and 0.75-0.94 for the manual and 3D methods respectively. The intra-operator reliability between the manual and 3D method and for all variables ranged from 0.69-0.88 for operator 1 and 0.68-86 for operator 2. The intra- and inter-operator reliability was substantial or excellent for all but two of the variables. These two variables were the IG of the upper right central incisor for operator 1 with an inter-operator reproducibility of 0.69 and the MD of the upper right central incisor for operator 2 with an inter-operator reproducibility of 0.68. Conclusions: Detailed tooth crown diameters can be undertaken using the new 3D laser scanner with substantial or excellent reproducibility.