Imaging Sci Dent.  2017 Dec;47(4):247-254. 10.5624/isd.2017.47.4.247.

Multispectral X-ray imaging to distinguish among dental materials

• Peter AC
• Schnaubelt M
• Gente M

• KMID: 2397839
• DOI: http://doi.org/10.5624/isd.2017.47.4.247

Abstract

PURPOSE
Dual-energy X-ray imaging is widely used today in various areas of medicine and in other applications. However, no similar technique exists for dental applications. In this study, we propose a dual-energy technique for dental diagnoses based on voltage-switching.
MATERIALS AND METHODS
The method presented in this study allowed different groups of materials to be classified based on atomic number, thereby enabling two-dimensional images to be colorized. Computer simulations showed the feasibility of this approach. Using a number of different samples with typical biologic and synthetic dental materials, the technique was applied to radiographs acquired with a commercially available dental X-ray unit.
RESULTS
This technique provided a novel visual representation of the intraoral environment in three colors, and is of diagnostic value when compared to state-of-the-art grayscale images, since the oral cavity often contains multiple permanent foreign materials.
CONCLUSION
This work developed a technique for two-dimensional dual-energy imaging in the context of dental applications and showed its feasibility with a commercial dental X-ray unit in simulation and experimental studies.

Keyword

Color; Radiographic Image Enhancement; Absorptiometry, Photon; Dental Materials

MeSH Terms

Absorptiometry, Photon
Computer Simulation
Dental Materials*
Diagnosis
Methods
Mouth
Radiographic Image Enhancement
Dental Materials

Figure

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  Fig. 1 Comparison of classical grayscale and new colored radiographs. The proposed method assigned distinct colors to different materials based on their atomic number. (A) Classical X-ray image, (B) New dual-energy analyis.

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  Fig. 2 Material composition of the first sample holder. Samples were glued onto a polymethyl methacrylate (PMMA) disc that was held by an aluminum rod from the X-ray unit (2c). To investigate the influence of material thickness on subsequent analysis, different sample dimensions were included.

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  Fig. 3 Schematic drawing of the second sample holder: 1. Implant; 2. Implant with abutment (PEEK); 3. Implant; 4. PMMA; 5. Ceramic crown; 6. Veneer; 7. Gold bridge; 8. Tooth; 9. Teeth of a pig with bone; 10. Sealer; 11 and 12. Gutta-percha points; 13. Tooth in , polymethyl methacrylate (PMMA); 14. PMMA; 15. Aluminum. PMMA, polymethyl methacrylate.

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  Fig. 4 Schematic drawing of the third sample holder. 1. Guttaflow; 2. Apexit; 3. Exp. Ormocer LC; 4. GrandioSo; 5. RealSeal; 6. Gutta-percha points; 7. Zirconium; 8. Lower jaw of a pig; 9. AH Plus; 10. Aluminum; 11. polymethyl methacrylate (PMMA).

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  Fig. 5 Results of the computer simulation. The quantity h was evaluated for different materials and varying sample thicknesses dm. The thicknesses of interest for dental applications are shaded in gray. Dotted horizontal lines separate groups of materials with similar properties. The thickness of the PMMA disc ddisc was assumed to be 2 mm (A) or 15 mm (B).

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  Fig. 6 Experimental results. The panels A, B, and C show the joined colored X-ray images (left) with corresponding histograms of the value of h (right). Depending on the value of h, four discrete material classes could be identified. Panel A displays the results from the first sample holder, panel B the results from the second sample holder and panel C the results from the third sample holder.

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