Assessing accuracy in measurements of orthodontic study model: Digital caliper vs 3 dimensional digital intraoral scanner

*Corresponding author: Bhoomika M Gowda. Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Assessing accuracy in measurements of orthodontic study model: Digital caliper vs 3 dimensional digital intraoral scanner Bhoomika M Gowda *, Naveen Suvarna and Asmitha Dayanad Department of orthodontics and dentofacial orthopaedics,AJ Institute of Dental Sciences,Mangalore,Karnataka,India. World Journal of Biology Pharmacy and Health Sciences, 2025, 23(03), 074-080 Publication history: Received on 22 July 2025; revised on 29 August 2025; accepted on 02 September 2025 Article DOI: https://doi.org/10.30574/wjbphs.2025.23.3.0804 Abstract Objectives: The interest on intraoral scanners for digital impressions has been growing and new devices are continuously introduced on the market. It is timely to verify whether the several scanners proposed for full-arch digital impressions have been tested under clinical conditions for validity, repeatability, reproducibility, as well as for time efficiency, and patient acceptance. Materials and methods: 20 Pretreatment study models of patients were obtained. The sample size was divided into Group 1 (prime scan),15 subjects under Group 2 (3 shape) and Group 3 (digital caliper).linear measurements were assessed via transferring STL file to NEMOCEPH software. One Way ANOVA and significant results will be analysed for post hoc test Results: is that there was no statistically significant difference between scanners in mean values of intracanine width. (P = 0.6), Inter premolar width (P = 0.75), intra molar width (P = 0.37), Arch length (P = 0.85), Arch perimeter (P = 0.94), mesiodistal width (of 41) (P = 0.34) and cervicoincisal width (of 41) (P = 0.58) respectively. Conclusion: Mean values of intercanine width, Interpremolar width, Intermolar width and arch perimeter were more when scanned using Prime Scanner. In addition, mean values of arch length and Cervicoinsical width (of 41) were more when scanned using Digital Caliper. Keywords: Intraoral Scanner; Nemo ceph; Digital caliper; Study model 1. Introduction Digital technology began entering dental and orthodontic practices with the advent of Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) in 1973. Innovations like intraoral scanning, cone beam computed tomography (CBCT), and 3D printing have since ushered in the digital era of dentistry. (1,2) Intraoral scanners represent a major milestone in this technological evolution and hold great promise for the future. These devices are designed to capture direct optical impressions in dentistry (3,4,5) Scanners have advanced considerably, now offering high-resolution mapping of both hard and soft tissues, making them a reliable replacement for traditional plaster models (6) The hassle of pouring and trimming plaster casts, along with the need to retrieve them from storage at every visit, is no longer necessary. Today, teeth can be viewed and manipulated in 3D on a computer screen across various devices, greatly enhancing communication with the patient. (7) World Journal of Biology Pharmacy and Health Sciences, 2025, 23(03), 074-080 75 For orthodontists, digital scanning offers numerous advantages, including enhanced diagnosis and treatment planning, higher case acceptance rates, quicker submission of records to laboratories and insurance providers, fewer retakes, reduced chairtime, standardized office procedures, decreased storage needs, faster lab turnaround, greater appliance accuracy, streamlined workflow, lower inventory costs, and potentially shorter treatment durations.Patients also benefit from improved case presentations and a more comfortable, less anxiety-inducing orthodontic experience. Additional advantages include shorter appointments, easier replacement of lost or broken appliances, and the possibility of reduced overall treatment time. (8) Before gaining acceptance within the orthodontic community, a scanner must demonstrate that it provides a valid and reliable representation of the dentoalveolar structures. Studies have shown that digital models produced by intraoral scanners are valid when compared to direct measurements taken from traditional plaster models, with the differences between the two methods falling within clinically acceptable limits (9.10) For example, Flugge and coworkers found that scanning with the ITero is less accurate than scanning with the D250 (11). In order to lean towards the usage of intraoral scanners, evidence should be provided that accuracy, reliability, time requirement, and patient perception of the several available intraoral scanners are comparable to that of the conventional technique for full-arch impressions The purpose of this study was to compare the reliability and validity of intraoral (prime scanner and 3 shape) scanners and digital caliper.The results of this study will help in validating the use of intraoral scanners in the field of orthodontics for Treatment Simulation, 3D Study Models,Integration with CBCT and Other Software and Clear Aligner Therapy 1.1. Aim To compare measurements on plaster model using digital caliper and on 3-dimensional digital model. 1.2. Objectives • To check intercanine width, interpremolar width,intermolar width,arch length,arch perimeter, cervicoincisal length and mesiodistal width of lower right central incisor using intraoral scanners. • To check intercanine width, interpremolar width, intermolar width, arch length, arch perimeter, cervicoincisal length and mesiodistal width of lower right central incisor using digital caliper. 2. Materials and methods The study was approved by the institutional Ethics Committee, AJ Institute of dental sciences. 2.1. Sampling technique The study participants will be selected based on convenience sampling, according to the following Inclusion and Exclusion criteria. 2.1.1. Inclusion criteria • No missing teeth except third molars. • Age 16-30 years. • No previous orthodontic treatment. 2.1.2. Exclusion criteria • Any habits like bruxism • Any fractures or carious lesion 2.2. Source of data Pretreatment orthodontic study models of 20 patients are obtained from department of orthodontics and dentofacial orthopedics, AJ institute of dental sciences, Mangalore. Alginate impression of upper and lower arch was taken and orthocal stone was poured into the tray to obtain study models. World Journal of Biology Pharmacy and Health Sciences, 2025, 23(03), 074-080 76 All teeth had normal morphology with no teeth in casts displaying visible attrition, caries or restorations affecting the mesio-distal crown diameter. 2.3. Scanning of models Each models was scanned with prime scanner, 3 Shape scanner and measured with digital caliper. Measurements taken were • Intercanine width (ICM) • Interpremolar width (IPW) • Intermolar width (IMW) • Arch length (diagonal line between mesiobuccal cusp tip of1st molar and mesial contact area of central incisor.Both right and left side ). • Arch perimeter. • Mesiodistal width of 41 (MDW) • Cervicoincisal length of 41. (CIL) The scanned casts was taken in STL format and put in nemoceph software and measurements were done by articulating in the software and 2 dimensional measurements were done accordingly. Figure 1 Measurements in Nemo Ceph Software 2.4. Sample size estimation N= [ (Z α + Z β )/C] 2 + 3 where: N= sample size Z α = 1.96 at 95% Confidence interval and error of 5% Z β = 0.842 C= 0.67 [correlation coefficient as computed from r = 0.585; from key article] So, N= [ (1.96 + 0.842)/0.67] 2 N= 20 World Journal of Biology Pharmacy and Health Sciences, 2025, 23(03), 074-080 77 Thus, minimum required sample size is 20 in each group. 3. Results The data was analysed using SPSS for Windows [SPSS ver 22.0, Armonk, NY]. Data was assessed for normality the Shapiro Wilk test. Descriptive statistics was used and results were presented as graphs and tables. Inter group comparison for normally distributed data was done using One Way ANOVA and significant results will be analysed for post hoc test. The level of significance was set at P ≤ 0.05. Figure 2 Comparision value Table 1 Comparison of mean values of various parameters measured using Digital Caliper Prime Scanner and 3 Shape N Mean SD df F P value ICM Digital Caliper 20 33.1 2.2 59 0.477 P = 0.6 Prime Scanner 20 33.7 2.3 NS 3 shape 20 33.1 2.07 IPW Digital Caliper 20 39.4 2.4 59 0.28 P = 0.75 Prime Scanner 20 39.9 2.4 NS 3 shape 20 39.5 2.5 IMW Digital Caliper 20 48.2 2.2 59 0.99 P = 0.37 Prime Scanner 20 49.1 2.1 NS 3 shape 20 48.4 2.3 Arch Length Digital Caliper 20 75.3 4.5 59 0.16 P = 0.85 Prime Scanner 20 74.9 4.9 NS 3 shape 20 74.5 5.1 Arch Perimeter Digital Caliper 20 91.3 5.8 59 0.05 P = 0.94 Prime Scanner 20 91.7 6.04 NS 3 shape 20 91.1 6.01 World Journal of Biology Pharmacy and Health Sciences, 2025, 23(03), 074-080 78 MDW of 41 Digital Caliper 20 5.2 0.49 59 1.1 P = 0.34 Prime Scanner 20 5.2 0.38 NS 3 shape 20 5.09 0.4 CIW of 41 Digital Caliper 20 6.91 0.87 59 0.54 P = 0.58 Prime Scanner 20 6.89 0.88 NS 3 shape 20 6.66 0.78 N-Number; SD-Standard Deviation; df-degree of freedom; NS-Not significant using One Way ANOVA Results is that there was no statistically significant difference between scanners in mean values of intracanine width. (P = 0.6), Interpremolar width (P = 0.75), intramolar width (P = 0.37), Arch length (P = 0.85), Arch perimeter (P = 0.94), mesiodistal width (of 41) (P = 0.34) and cervicoincisal width (of 41) (P = 0.58) respectively. 4. Discussion The purpose of a dental impression is to copy a patient’s intraoral situation, transforming it into a model. Obtaining a model of good quality, true to the original, is extremely important for the success of a treatment. Different types of materials and impression techniques have been used over the years to achieve the desired accuracy (12) It was a remarkable observation that only few studies have evaluated complete-arch scans acquired directly in the patient’s mouth (13,14,15). Verification of accuracy and reliability should be a prerequisite for the clinical application of any new technology (16) The study models selected for this study comprised Class I, Class II, and Class III malocclusions. They were chosen to represent the variety of patients who could be encountered in orthodontic practice. six of the 10 cases demonstrated mild to moderate crowding, one had spacing and one case, 3 Class I occlusion with well-aligned arches. As far as reproducibility is concerned, crowding seems to play an important role in the results because of the accumulation of errors that occurred in single measurements (17). The differences found for crowding seemed not to be dependent on the severity of crowding, concluding that digital models can also be used for cases with crowding of over >4.5 mm Identification of points is a source of error. For this reason, dots were placed on a selection of landmarks in black pen on the study models. These points were used to eliminate landmark identification error in the measurements of reference distances Flügge et al (11)analyzed digital images produced by plaster model scanning and chairside intraoral scanning. Wiranto et al. (18)and Naidu et al (19). evaluated measurements from plaster models with a digital calliper, as it is clinical routine, and digital models with computer software. The main conclusion was that both methods were clinically acceptable, reliable, and reproducible. It may not be possible to truly compare dental plaster models with digital ones since there are differences in measurement techniques. Use of callipers has been found to be less accurate than using computer software.However, there are several drawbacks that currently limit the use of intraoral scanners in clinical practice. The high cost of the intraoral scanner, the annual fees, along with the associated hardware and software, and the need to be connected to a network, do not allow the existence of an intraoral scanner in every orthodontic office (20). Limitation of the study could be the measurement of dental casts, the sharpened points of the callipers caused wear of the casts and this may have affected measurements of mesio-distal tooth width over repeated measurements. 5. Conclusion Mean values of intercanine width, Interpremolar width, Intermolar width and arch perimeter were more when scanned using Prime Scanner. In addition, mean values of arch length and Cervicoinsical width (of 41) were more when scanned using Digital Caliper. World Journal of Biology Pharmacy and Health Sciences, 2025, 23(03), 074-080 79 Compliance with ethical standards Disclosure of conflict of interest No conflict of interest to be disclosed. References [1] Harrell RE. An evidence-based evaluation of three-dimensional scanning technology in orthodontic practice. The Journal of Multidisciplinary Care. 2018;4:17-20. [2] Mangano A, Beretta M, Luongo G, Mangano C, Mangano F. 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