Restorative Dentistry & Endodontics

The effects of image acquisition control of digital X-ray system on radiodensity quantification: Wook-Jin Seong, Hyeon-Cheol Kim, Soocheol Jeong, Youngcheul Heo, Woo-Bin Song, Mansur Ahmad; Restor Dent Endod 2013;38(3):146-153. Published online August 23, 2013; DOI: https://doi.org/10.5395/rde.2013.38.3.146

Abstract PDF PubReader ePub: Objectives
Aluminum step wedge (ASW) equivalent radiodensity (eRD) has been used to quantify restorative material's radiodensity. The aim of this study was to evaluate the effects of image acquisition control (IAC) of a digital X-ray system on the radiodensity quantification under different exposure time settings.
Materials and Methods
Three 1-mm thick restorative material samples with various opacities were prepared. Samples were radiographed alongside an ASW using one of three digital radiographic modes (linear mapping (L), nonlinear mapping (N), and nonlinear mapping and automatic exposure control activated (E)) under 3 exposure time settings (underexposure, normal-exposure, and overexposure). The ASW eRD of restorative materials, attenuation coefficients and contrasts of ASW, and the correlation coefficient of linear relationship between logarithms of gray-scale value and thicknesses of ASW were compared under 9 conditions.
Results
The ASW eRD measurements of restorative materials by three digital radiographic modes were statistically different (p = 0.049) but clinically similar. The relationship between logarithms of background corrected grey scale value and thickness of ASW was highly linear but attenuation coefficients and contrasts varied significantly among 3 radiographic modes. Varying exposure times did not affect ASW eRD significantly.
Conclusions
Even though different digital radiographic modes induced large variation on attenuation of coefficient and contrast of ASW, E mode improved diagnostic quality of the image significantly under the under-exposure condition by improving contrasts, while maintaining ASW eRDs of restorative materials similar. Under the condition of this study, underexposure time may be acceptable clinically with digital X-ray system using automatic gain control that reduces radiation exposure for patient.

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A comparative study on radiopacity of root canal sealers: Tae-Min Kim, Seo-Kyoung Kim, In-Nam Hwang, Yun-Chan Hwang, Byung-Cheol Kang, Suk-Ja Yoon, Jae-Seo Lee, Won-Mann Oh; J Korean Acad Conserv Dent 2009;34(1):61-68. Published online January 31, 2009; DOI: https://doi.org/10.5395/JKACD.2009.34.1.061

This study was performed to assess the radiopacity of a variety of root canal sealers according to the specification concerning root canal sealers.

Ten materials including Tubli-Seal™, Kerr Pulp Canal Sealer™, AH 26®, AH plus®, AH plus jet™, Ad sea l™, Sealapex™, NOGENOL™, ZOB seal™, Epiphany™ and dentin were evaluated in this study. In the first part, densitometric reading of an each step of aluminum step wedge on occlusal film was performed at different voltage and exposure time. In the second part, ten specimens were radiographed simultaneously with an aluminum step wedges on the occlusal films under decided condition. The mean radiographic den sity values of the materials were transformed into radiopacity expressed equivalent thickness of aluminum (mm Al).

The following results were obtained.

1. Among the various conditions, the appropriate voltage and exposure time that meet the requirement density was 60 kVp at 0.2 s

2. All of the materials had greater radiopacity than 3 mm Al requirement of ANSI/ADA specification No. 57 (2000) and ISO No. 6876 (2001) standards.

3. The radiopacity of materials increased as thickness of materials increased.

4. The mm Al value of each specimen at 1mm in thickness has a significant difference in the statistics.

It suggests that root canal sealers have a sufficient radiopacity that meet the requirement.

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A comparative study on radiopacity of canal filling and retrograde root-end filling materials: Yong-Sang Kim, Seo-Kyong Kim, Yun-Chan Hwang, In-Nam Hwang, Won-Mann Oh; J Korean Acad Conserv Dent 2008;33(2):107-114. Published online March 31, 2008; DOI: https://doi.org/10.5395/JKACD.2008.33.2.107

Abstract PDF PubReader ePub

This study was performed to assess the radiopacity of a variety of canal filling and retrograde root-end filling materials according to the specification concerning root canal obturation materials.

Ten materials including Gutta-percha pellets, amalgam, Fuji II LC, Dyract® AP, Super EBA®, IRM®, AH 26®, Sealapex™, Tubli-Seal™ and dentin were evaluated in this study. In the first part, densitometric reading of an each step of aluminum step wedge on occlusal film were performed at 60 kVp (0.2, 0.3, 0.4 s), 70 kVp (0.2, 0.3, 0.33 s) to decide appropriate voltage and exposure time. In the second part, ten specimens which are 5 mm in diameter and 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm in thickness, were fabricated from each material studied. The specimens were radiographed simultaneously with an aluminum step wedge under decided condition (60 kVp, 0.2 s). The mean radiographic density values of the materials were transformed into radiopacity expressed equivalent thickness of aluminum (mm Al).

The following results were obtained.

Among the various conditions including 0.2 s, 0.3 s, 0.4 s at 60 kVp and 0.2 s, 0.3 s, 0.33 s at 70 kVp, the appropriate voltage and exposure time that meet the requirement of density from 0.5 to 2.0 was 0.2 s at 60 kVp.

All of the materials in this study had greater radiopacity than the minimun level recommended by ISO No. 4049 standards.

Most of the materials had greater radiopacity than 3 mm Al requirement of ANSI/ADA specification No. 57 (2000) and ISO No. 6876 (2001) standards except for Fuji II LC and Dyract.

It suggests that all experimental canal filling and retrograde root-end filling materials have a sufficient radiopacity that meet the requirement concerning root canal obturation materials except for Fuji II LC and Dyract.

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Evaluation of the radiopacity and cytotoxicity of resinous root canal sealers: Chang-Kyu Kim, Hyun-Wook Ryu, Hoon-Sang Chang, Byung-Do Lee, Kyung-San Min, Chan-Ui Hong; J Korean Acad Conserv Dent 2007;32(5):419-425. Published online September 30, 2007; DOI: https://doi.org/10.5395/JKACD.2007.32.5.419

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The aim of this study was to evaluate the radiopacity and cytotoxicity of three resin-based (AH 26, EZ fill and AD Seal), a zinc oxide-eugenol-based (ZOB Seal), and a calcium hydroxide-based (Sealapex) root canal sealers. Specimens, 10 mm in diameter and 1 mm in thickness, were radiographed simultaneously with an aluminum step wedge using occlusal films, according to ISO 6876/2001 standards. Radiographs were digitized, and the radiopacity of sealers was compared to the different thicknesses of the aluminum step wedge, using the Scion image software. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of each material was determined in immortalized human periodontal ligament (IPDL) cells.

The results demonstrated that EZ fill was the most radiopaque sealer, while Sealapex was the least radiopaque (p < 0.05). AH 26, AD Seal and ZOB Seal presented intermediate radiopacity values. All the materials evaluated, except for Sealapex, presented the minimum radiopacity required by ISO standards. The cell viabilities of resin-based root canal sealers were statistically higher than that of other type of root canal sealers through the all experimental time. Further, EZ fill showed statistically lower cell viability in 24 and 48 hours compared to AD Seal and in 72 hours compared to all other resin-based root canal sealers. However, there was no correlation between the radiopacity and cytotoxicity of three resin-based root canals sealers (p > 0.05).

These results indicate that resin-based root canal sealer is more biocompatible and has advantage in terms of radiopacity.

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