Reliability of measurements on virtual models obtained from scanning of impressions and conventional plaster models

Abstract

Aim: To evaluate the reliability of linear measurements in virtual models by comparing measurements performed on virtual models obtained from alginate impression scans, plaster model and measurements performed on conventional plaster model. Methods: The sample comprised 26 randomly selected patients to have impressions of their upper and lower jaws taken using alginate and their bite registration using a wax bite. The virtual models were obtained by scanning the alginate impression and the plaster model in a laser surface scanner (R700; 3Shape, Copenhagen, Denmark), and the measurements were performed using the Ortho Analyser (3Shape) proprietary software. The linear measurements of the size of the teeth mesial to distal, arch perimeter, intercanine distance and intermolar distance in the upper and lower arches were performed on plaster models, digital impressions and digital models, by three observers and repeated after 15 days on 8 models for intra-observer evaluations. Data were tabulated and analyzed statistically. Intra-class correlation to check the agreement of intra and inter-observers and ANOVA test were used to analyze the differences between measurements of digital models from impression and digital models from plaster. Results: The results showed a statistically significant difference (pd"0.05) for the posterior teeth, anterior teeth, upper arch perimeter and lower inter-canine distance, comparing the digital models with plaster models, but these differences are considered clinically non-significant. Conclusions: Digital models were proven be reliable and clinically acceptable for measuring tooth width, perimeter arches, intercanine and intermolar distances.

Variations in dental arch morphology are outcomes of the complex adaptive system associated with the developmental variation of hypodontia

“…An ICC reading of greater than 0.75 is indicative of good reliability and an ICC of 1 is an identical match in measurements. Studies have also indicated that digital models are a more reliable and clinically acceptable method of assessing inter-molar and inter-canine distances [5,[13][14][15][16]. In the literature, it is suggested that variations can arise in measurements relating to the operator position and point chosen on the digitized casts.…”

“…When many models are collected over a long period, they can take up a considerable amount of space which also incurs a cost. Additionally, when measuring and using models over a long period they are subjected to a degree of wear and tear, which can alter the measurements [12][13][14][15][16].…”

“…With the development of scanning technologies, it has become increasingly relevant to apply this technology to the dental arch and test the accuracy of measuring dental scans between operators [14].…”

Variation in tooth crown size and shape are outcomes of the complex adaptive system associated with the tooth number variation of hypodontia

“…Variability also exists between operators measuring with traditional calipers, plaster models, and where the points have been 5.583 0.08299 n/a n/a n/a Mean: 0.091012857 4.195 0.9016 n/a n/a n/a Mean: 0.5820925 marked for them to measure; simply due to the slight variation in the manual positioning of the calipers [13]. Previous studies have demonstrated that, while there is inter-operator error when measuring on a 3D model, this is still less than traditional plaster models and calipers [13][14][15]. Digital models may be more reliable than hand calipers because of the ability to zoom in and rotate the models in multiple planes [15].…”

The Reliability and Validity of the Measurements in Unilateral Cleft Lip and Palate Laser Scanned 3D Dental Casts

“…Affected patients suffer a multitude of problems, including both functional and aesthetic diversities. A wide variety of dental anomalies such as angulation and alignment of the tooth, missing tooth, severe crowding are observed in CLP patients compared to the normal patients [14][15][16][17][18][19][20][21][22]. The maxillary dental arch dimension is compromised in affected people than normal patients [23].…”