Korean J Orthod.  2014 Sep;44(5):229-235. 10.4041/kjod.2014.44.5.229.

Assessment of metal artifacts in three-dimensional dental surface models derived by cone-beam computed tomography

• Nabha W
• Hong YM
• Cho JH
• Hwang HS

• KMID: 1726416
• DOI: http://doi.org/10.4041/kjod.2014.44.5.229

Abstract

OBJECTIVE
The aim of this study was to assess artifacts induced by metallic restorations in three-dimensional (3D) dental surface models derived by cone-beam computed tomography (CBCT).
METHODS
Fifteen specimens, each with four extracted human premolars and molars embedded in a plaster block, were scanned by CBCT before and after the cavitated second premolars were restored with dental amalgam. Five consecutive surface models of each specimen were created according to increasing restoration size: no restoration (control) and small occlusal, large occlusal, disto-occlusal, and mesio-occluso-distal restorations. After registering each restored model with the control model, maximum linear discrepancy, area, and intensity of the artifacts were measured and compared.
RESULTS
Artifacts developed mostly on the buccal and lingual surfaces. They occurred not only on the second premolar but also on the first premolar and first molar. The parametric values increased significantly with increasing restoration size.
CONCLUSIONS
Metallic restorations induce considerable artifacts in 3D dental surface models. Artifact reduction should be taken into consideration for a proper diagnosis and treatment planning when using 3D surface model derived by CBCT in dentofacial deformity patients.

Keyword

Cone-beam computed tomography; Three-dimensional surface model; Artifact; Metallic restoration

MeSH Terms

Artifacts*
Bicuspid
Cone-Beam Computed Tomography*
Dental Amalgam
Dentofacial Deformities
Diagnosis
Humans
Molar
Dental Amalgam

Figure

• 

  Figure 1 Illustration of the restorations. A, Small occlusal restoration; B, large occlusal restoration; C, disto-occlusal restoration; D, mesio-occluso-distal restoration.

• 

  Figure 2 Quantitative assessment of artifacts on the basis of discrepancies of two models, each restoration model and no restoration model as the control. The present figures show the discrepancies between a mesio-occluso-distal restoration and the control. A and B, Maximum linear discrepancy was measured as the distance between the shells at the most protruded point of the graphic. C and D, Artifact area was defined as an area of discrepancy over 0.5 mm. E and F, Artifact intensity was defined as the sum of five discrepancy areas measured in cross-sectional graphics captured at the level of the maximum linear discrepancy and 0.5 and 1.0 mm above and below.

• 

  Figure 3 Color-mapped graphics obtained by registering three-dimensional surface models of the restorations with the control (no restoration). Discrepancies between the shells indicate artifacts due to amalgam restoration. Blue and red represent the minimum and maximum discrepancies, respectively. A, Small occlusal restoration; B, large occlusal restoration; C, disto-occlusal restoration; D, mesio-occluso-distal restoration.

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