Advertisement
Journal of Prosthetic Dentistry

A virtual analysis of the precision and accuracy of 3-dimensional ear casts generated from smartphone camera images

Published:February 26, 2021DOI:https://doi.org/10.1016/j.prosdent.2020.12.041

      Abstract

      Statement of problem

      The anatomic complexity of the ear challenges conventional maxillofacial prosthetic rehabilitation. The introduction of specialized scanning hardware integrated into computer-aided design and computer-aided manufacturing (CAD-CAM) workflows has mitigated these challenges. Currently, the scanning hardware required for digital data acquisition is expensive and not readily available for prosthodontists in developing regions.

      Purpose

      The purpose of this virtual analysis study was to compare the accuracy and precision of 3-dimensional (3D) ear models generated by scanning gypsum casts with a smartphone camera and a desktop laser scanner.

      Material and methods

      Six ear casts were fabricated from green dental gypsum and scanned with a laser scanner. The resultant 3D models were exported as standard tessellation language (STL) files. A stereophotogrammetry system was fabricated by using a motorized turntable and an automated microcontroller photograph capturing interface. A total of 48 images were captured from 2 angles on the arc (20 degrees and 40 degrees from the base of the turntable) with an image overlap of 15 degrees, controlled by a stepper motor. Ear 1 was placed on the turntable and captured 5 times with smartphone 1 and tested for precision. Then, ears 1 to 6 were scanned once with a laser scanner and with smartphones 1 and 2. The images were converted into 3D casts and compared for accuracy against their laser scanned counterparts for surface area, volume, interpoint mismatches, and spatial overlap. Acceptability thresholds were set at <0.5 mm for interpoint mismatches and >0.70 for spatial overlap.

      Results

      The test for smartphone precision in comparison with that of the laser scanner showed a difference in surface area of 774.22 ±295.27 mm2 (6.9% less area) and in volume of 4228.60 ±2276.89 mm3 (13.4% more volume). Both acceptability thresholds were also met. The test for accuracy among smartphones 1, 2, and the laser scanner showed no statistically significant differences (P>.05) in all 4 parameters among the groups while also meeting both acceptability thresholds.

      Conclusions

      Smartphone cameras used to capture 48 overlapping gypsum cast ear images in a controlled environment generated 3D models parametrically similar to those produced by standard laser scanners.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'

      Subscribe:

      Subscribe to Journal of Prosthetic Dentistry
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect

      References

        • Farook T.H.
        • Jamayet N Bin
        • Abdullah J.Y.
        • Asif J.A.
        • Rajion Z.A.
        • Alam M.K.
        Designing 3D prosthetic templates for maxillofacial defect rehabilitation: A comparative analysis of different virtual workflows.
        Comput Biol Med. 2020; 118: 103646
        • Jamayet N Bin
        • Abdullah J.Y.
        • Rahman A.M.
        • Husein A.
        • Alam M.K.
        A fast and improved method of rapid prototyping for ear prosthesis using portable 3D laser scanner.
        J Plast Reconstr Aesthetic Surg. 2018; 71: 946-953
        • Farook T.H.
        • Jamayet N.B.
        • Abdullah J.Y.
        • Rajion Z.A.
        • Alam M.K.
        A systematic review of the computerized tools and digital techniques applied to fabricate nasal, auricular, orbital and ocular prostheses for facial defect rehabilitation.
        J Stomatol Oral Maxillofac Surg. 2020; 121: 268-277
        • Oncescu V.
        • O’Dell D.
        • Erickson D.
        Smartphone based health accessory for colorimetric detection of biomarkers in sweat and saliva.
        Lab Chip. 2013; 13: 3232-3238
        • Stuani V.T.
        • Ferreira R.
        • Manfredi G.G.P.
        • Cardoso M.V.
        • Sant’Ana A.C.P.
        Photogrammetry as an alternative for acquiring digital dental models: a proof of concept.
        Med Hypotheses. 2019; 128: 43-49
        • Ozturk A.
        • Dolanmaz D.
        • Celik S.
        • Isik K.
        • Karabork H.
        • Yildiz F.
        • et al.
        The use of stereophotogrammetry in oral surgery: Measurement of area changes after secondary epithelization and grafting vestibuloplasties.
        Indian J Dent Res. 2012; 23: 770
        • Dindaroğlu F.
        • Kutlu P.
        • Duran G.S.
        • Görgülü S.
        • Aslan E.
        Accuracy and reliability of 3D stereophotogrammetry: a comparison to direct anthropometry and 2D photogrammetry.
        Angle Orthod. 2016; 86: 487-494
        • Beh Y.H.
        • Farook T.H.
        • Jamayet N Bin
        • Dudley J.
        • Rashid F.
        • Barman A.
        • et al.
        Evaluation of the differences between conventional and digitally developed models used for prosthetic rehabilitation in a case of untreated palatal cleft.
        Cleft Palate-Craniofacial J. 2020; 58: 386-390
        • Hasan Farook T.
        • Barman A.
        • Yap Abdullah J.
        • Bin Jamayet N.
        Optimization of prosthodontic computer-aided designed models: a virtual evaluation of mesh quality reduction using open source software.
        J Prosthodont. 2021; 30: 420-429
        • Abdullah J.
        • Abdullah A.
        • Hadi H.
        • Husein A.
        • Rajion Z.
        Comparison of STL skull models produced using open-source software versus commercial software.
        Rapid Prototyp J. 2019; 25: 1585-1591
        • Farook T.H.
        • Abdullah J.Y.
        • Bin Jamayet N.
        • Alam M.K.
        Percentage of mesh reduction appropriate for designing digital obturator prostheses on personal computers.
        J Prosthet Dent. 2022; 128: 219-224
        • Elbashti M.E.
        • Sumita Y.I.
        • Aswehlee A.M.
        • Seelaus R.
        Smartphone application as a low-cost alternative for digitizing facial defects: is it accurate enough for clinical application?.
        Int J Prosthodont. 2019; 32: 541-543
        • Sim J.-Y.
        • Jang Y.
        • Kim W.-C.
        • Kim H.-Y.
        • Lee D.-H.
        • Kim J.-H.
        Comparing the accuracy (trueness and precision) of models of fixed dental prostheses fabricated by digital and conventional workflows.
        J Prosthodont Res. 2019; 63: 25-30
        • Sharma N.
        • Cao S.
        • Msallem B.
        • Kunz C.
        • Brantner P.
        • Honigmann P.
        • et al.
        Effects of steam sterilization on 3D printed biocompatible resin materials for surgical guides—an accuracy assessment study.
        J Clin Med. 2020; 9: 1506
        • Guindon B.
        • Zhang Y.
        Application of the Dice coefficient to accuracy assessment of object-based image classification.
        Can J Remote Sens. 2017; 43: 48-61
        • Elbashti M.E.
        • Sumita Y.I.
        • Kelimu S.
        • Aswehlee A.M.
        • Awuti S.
        • Hattori M.
        • et al.
        Application of digital technologies in maxillofacial prosthetics literature: a 10-year observation of five selected prosthodontics journals.
        Int J Prosthodont. 2019; 32: 45-50
        • Farook T.H.
        • Mousa M.A.
        • Jamayet N.B.
        Method to control tongue position and open source image segmentation for cone-beam computed tomography of patients with large palatal defect to facilitate digital obturator design.
        J Oral Maxillofac Surgery, Med Pathol. 2020; 32: 61-64
        • Farook T.H.
        • Jamayet N.B.
        A review of prostheses fabricated for rehabilitation of nasal septal defect using digital workflow.
        Otorinolaryngologia. 2020; 70: 57-60