Impact of different complete coverage onlay preparation designs and the intraoral scanner on the accuracy of digital scans

Guilherme Schmitt de Andrade; Julio Nogueira Luz; João Paulo Mendes Tribst; Eliseo Pablo Chun; Adriano Bressane; Alexandre Luiz Souto Borges; Guilherme de Siqueira Ferreira Anzaloni Saavedra

doi:10.1016/j.prosdent.2022.05.001

Impact of different complete coverage onlay preparation designs and the intraoral scanner on the accuracy of digital scans

J Prosthet Dent. 2022 Jun 15:S0022-3913(22)00278-5. doi: 10.1016/j.prosdent.2022.05.001. Online ahead of print.

Authors

Guilherme Schmitt de Andrade¹, Julio Nogueira Luz², João Paulo Mendes Tribst³, Eliseo Pablo Chun⁴, Adriano Bressane⁵, Alexandre Luiz Souto Borges⁶, Guilherme de Siqueira Ferreira Anzaloni Saavedra⁶

Affiliations

¹ Assistant Professor, Center of Biological and Health Sciences, School of Dentistry, Western Paraná State University (Unioeste), Cascavel, PR, Brazil. Electronic address: guisdandrade@hotmail.com.
² Assistant Professor, Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University - UNESP, São José dos Campos, SP, Brazil; Adjunct Professor, Department of Dentistry, School of Dentistry, University of Guarulhos (UNG), Guarulhos, SP, Brazil.
³ Assistant Professor, Department of Dental Materials, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
⁴ Faculty, School of Dentistry, Espiritu Santo University, Samborondon, Ecuador.
⁵ Associate Professor, Applied Oral Health Sciences Post-Graduate Program, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, SP, Brazil.
⁶ Associate Professor, Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, SP, Brazil.

PMID: 35717209
DOI: 10.1016/j.prosdent.2022.05.001

Abstract

Statement of problem: The trueness and precision of intraoral scanners (IOSs) and the effect of intracoronal restorations have been reported. However, studies addressing the accuracy of IOSs in reproducing different complete coverage onlay preparation designs are lacking.

Purpose: The purpose of this in vitro study was to evaluate the influence of complete coverage onlay preparation design and intraoral scanning devices on the accuracy of digital scans in terms of trueness and precision.

Material and methods: Three preparation designs on the mandibular first molar were considered: a traditional preparation design with isthmus reduction (IST), a traditional preparation design without isthmus reduction (wIST), and simplified nonretentive preparation (nRET). Digital scans of epoxy resin mandibular arch reference models of the preparations (containing second premolar, first molar, and second molar) were obtained by using 3 IOSs (iTero Element 2 [ELE], Trios 3 [TRI], and Primescan [PRI]) (n=10). Trueness (μm) and precision (μm) were analyzed by superimposing the digital scan on the digital reference models obtained with a high-accuracy industrial scanner (ATOS Core 80) in a tridimensional metrology software program. Accuracy was quantified by the absolute deviation (μm). Local and overall mean positive and negative deviations for trueness were also obtained. Data were analyzed by using the Kruskal-Wallis and Dunn tests with a statistical software program (α=.05).

Results: The nonretentive preparation groups obtained higher trueness (3.8 μm) and precision (2.7 μm) than the IST and wIST groups (trueness=7.5 to 6.3 μm, precision=5.5 to 4.6 μm). Trueness values were lower with ELE×IST (16 μm), followed by ELE×wIST (13 μm), and PRI×IST (7.8 μm). In general, no difference was found between PRI and TRI scanners (6.3 to 5.9 μm), with lower performance for ELE (13 μm). Positive deviations were higher on the proximal box of the IST and wIST preparation and on the occlusal box of the IST group. Negative deviation was higher on the ELE×IST occlusal box.

Conclusions: Different intraoral scanners and preparation designs influenced the accuracy of digital scans. A more complex preparation such as IST and wIST showed higher deviation. The iTero Element 2 scanner exhibited higher deviation for both trueness and precision.