Does partial adhesive preparation design and finish line depth influence trueness and precision of intraoral scanners?

Elsevier

Available online 10 March 2023

The Journal of Prosthetic DentistryAuthor links open overlay panel, , , , , , AbstractStatement of problem

Intraoral scanners (IOSs) are widely used for partial-coverage adhesive restorations, but data on their performance in such preparations with complex geometries are sparse.

Purpose

The purpose of this in vitro study was to investigate whether the partial-coverage adhesive preparation design and finish line depth affect the trueness and precision of different IOSs.

Material and methods

Seven partial-coverage adhesive preparation designs (4 different onlays, 2 endocrowns, and 1 occlusal veneer) were tested on copies of the same tooth placed in a typodont mounted on a mannequin. Each preparation was scanned 10 times with 6 different IOSs (total 420 scans) under the same light conditions. Trueness and precision, defined according to the International Organization for Standardization (ISO) 5725-1 standard, were analyzed with a best-fit algorithm by superimposition. The obtained data were analyzed by a 2-way analysis of variance to examine the effects of partial-coverage adhesive preparation design, IOS, and their interactions (α=.05).

Results

Significant differences were found among different preparation designs and IOSs (P<.05) in terms of both trueness and precision. Significant differences were also found among mean positive and negative values (P<.05). Moreover, crosslinks observed between the preparation area and the adjacent teeth correlated with the finish line depth.

Conclusions

Complex partial adhesive preparation designs affect the trueness and precision of IOSs, resulting in significant differences among them. Interproximal preparations should take into account the IOS’s resolution and placing the finish line close to adjacent structures should be avoided.

Section snippetsMaterial and methods

Seven identical copies of a typodont maxillary right molar (Frasaco AG-3; Frasaco GmbH) were subjected to different partial restoration preparations by a single experienced operator (N.S.). The preparations reflected commonly used designs to restore extensively damaged teeth (Fig. 1).31,32

Preparation OB3 was a complete-coverage onlay with 3-mm-deep interproximal boxes (2 ±0.5-mm occlusal reduction) prepared with 2 cylindrical diamond rotary instruments (959KR.314.018 and 8959KR.314.018; Komet

Results

The IOS trueness results are presented as means (positive and negative) and standard deviations in Figure 5. The trueness results for the preparation designs are presented in Figure 6. Two-way ANOVA showed significant differences (P<.01) among both the preparation designs and the IOSs. The post hoc Tukey test results are displayed in Tables 2 and 3.

In terms of IOS positive means, the 3Shape TRIOS 3 (3S) and iTero Element 5D (IT) showed higher trueness than the Medit i500 (I5) (both P<.01) and

Discussion

Different variables may affect the trueness and precision of an IOS. This study attempted to simulate a clinical scenario to evaluate the trueness and precision of different IOSs with different preparation designs for partial-coverage adhesive restorations. The mean positive and negative values obtained from the surface deviation analyses were used as independent variables. Consistent with Kim et al,29 the mean positive values were always higher than the negative values in the trueness

Conclusions

Based on the findings of this in vitro study, the following conclusions were drawn:

1.

The partial-coverage adhesive preparation designs significantly affected the trueness and precision of the IOSs tested.

2.

The IOSs showed significant differences in trueness and precision.

3.

Interproximal preparations should take into account the IOS’s resolution, and placing the finish line too close to adjacent structures should be avoided.

CRediT authorship contribution statement

Andrea Baldi: Writing – original draft, software. Allegra Comba: Supervision. Davide Rozzi: Investigation. Gabriel Kalil Rocha Pereira: Writing – review & editing. Luiz Felipe Valandro: Validation. Riccardo Michelotto Tempesta: Visualization. Nicola Scotti: Project administration, Conceptualization.

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© 2023 by the Editorial Council for the Journal of Prosthetic Dentistry.

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