J Adv Prosthodont.  2013 Nov;5(4):452-456. 10.4047/jap.2013.5.4.452.

White light scanner-based repeatability of 3-dimensional digitizing of silicon rubber abutment teeth impressions

• Jeon JH
• Lee KT
• Kim HY
• Kim JH
• Kim WC

• KMID: 2176538
• DOI: http://doi.org/10.4047/jap.2013.5.4.452

Abstract

PURPOSE
The aim of this study was to evaluate the repeatability of the digitizing of silicon rubber impressions of abutment teeth by using a white light scanner and compare differences in repeatability between different abutment teeth types.
MATERIALS AND METHODS
Silicon rubber impressions of a canine, premolar, and molar tooth were each digitized 8 times using a white light scanner, and 3D surface models were created using the point clouds. The size of any discrepancy between each model and the corresponding reference tooth were measured, and the distribution of these values was analyzed by an inspection software (PowerInspect 2012, Delcamplc., Birmingham, UK). Absolute values of discrepancies were analyzed by the Kruskal-Wallis test and multiple comparisons (alpha=.05).
RESULTS
The discrepancy between the impressions for the canine, premolar, and molar teeth were 6.3 microm (95% confidence interval [CI], 5.4-7.2), 6.4 microm (95% CI, 5.3-7.6), and 8.9 microm (95% CI, 8.2-9.5), respectively. The discrepancy of the molar tooth impression was significantly higher than that of other tooth types. The largest variation (as mean [SD]) in discrepancies was seen in the premolar tooth impression scans: 26.7 microm (95% CI, 19.7-33.8); followed by canine and molar teeth impressions, 16.3 microm (95% CI, 15.3-17.3), and 14.0 microm (95% CI, 12.3-15.7), respectively.
CONCLUSION
The repeatability of the digitizing abutment teeth's silicon rubber impressions by using a white light scanner was improved compared to that with a laser scanner, showing only a low mean discrepancy between 6.3 microm and 8.9 microm, which was in an clinically acceptable range. Premolar impression with a long and narrow shape showed a significantly larger discrepancy than canine and molar impressions. Further work is needed to increase the digitizing performance of the white light scanner for deep and slender impressions.

Keyword

Dental white light scanner; Repeatability; Digital impression; 3D-surface model

MeSH Terms

Bicuspid
Molar
Rubber*
Silicones*
Tooth*
Rubber
Silicones

Figure

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  Fig. 1 Impressions taken by the extra light body of a silicone impression material; (A) upper right canine, (B) upper right first premolar and (C) upper right first molar.

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  Fig. 2 The white light scanner (Identica®, Medit, Seoul, Korea) used in this study.

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  Fig. 3 Seven color-difference maps of scans of the canine abutment tooth impression (A-G) showing fit alignment of digital impression data compared to the reference model. The color-difference map represents the exact fit as green, positive discrepancy greater than the reference model as yellow or red, and negative discrepancy smaller than the reference model as turquoise to blue.

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  Fig. 4 Seven color-difference maps of scans of the premolar abutment tooth impression (A-G) showing fit alignment of digital impression data compared to the reference model. The color-difference map represents the exact fit as green, positive discrepancy greater than the reference model as yellow or red, and negative discrepancy smaller than the reference model as turquoise to blue.

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  Fig. 5 Seven color-difference maps of scans of the molar abutment tooth impression (A-G) showing fit alignment of digital impression data compared to the reference model. The color-difference map represents the exact fit as green, positive discrepancy greater than the reference model as yellow or red, and negative discrepancy smaller than the reference model as turquoise to blue.

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