|Year : 2014 | Volume
| Issue : 6 | Page : 783-787
|Evaluation of two-dimensional and three-dimensional radiography with direct surgical assessment of periodontal osseous defects: A clinical Study
Priyanka Pahwa1, Arundeep Kaur Lamba1, Harpreet Grewal2, Farrukh Faraz1, Shruti Tandon1, Neha Yadav1
1 Department of Periodontics and Oral Implantology, Maulana Azad Institute of Dental Sciences, New Delhi, India
2 Department of Dentistry, University College of Medical Sciences, New Delhi, India
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|Date of Submission||01-Dec-2011|
|Date of Decision||10-Sep-2014|
|Date of Acceptance||07-Jan-2015|
|Date of Web Publication||02-Mar-2015|
| Abstract|| |
Aim: To compare the diagnostic values of radiovisiograph (RVG) and computed tomography (CT) images in comparison with direct surgical measurements for the determination of periodontal bone loss.
Materials and Methods: Thirty-one vertical defects were included for direct measurements during surgery with a periodontal probe. RVG and CT images were taken prior to the surgery. Similar measurements were done on their images and compared with the direct surgical values.
Results: Mean difference (in mm) of RVG and CT scan in vertical defects, and intrabony component was 0.814, 0.474 and 0.073, 0.066 respectively. Intra class correlation of CT scan (0.997 and 0.990) was highest with the smallest length of 95% confidence interval. CT scan furthermore depicted maximum agreement with the surgical value. CT scan overestimated in the maximum percentage of sites in vertical defects. CT scan outscored over RVG in evaluation of the osseous defects.
Conclusions: CT scan demonstrated more precise and clinically useful images of the osseous defects closer to the gold standard.
Keywords: Alveolar bone loss, imaging, radiography
|How to cite this article:|
Pahwa P, Lamba AK, Grewal H, Faraz F, Tandon S, Yadav N. Evaluation of two-dimensional and three-dimensional radiography with direct surgical assessment of periodontal osseous defects: A clinical Study. Indian J Dent Res 2014;25:783-7
Advanced diagnostic tools and techniques have revolutionized the way diseases are diagnosed and treated in today's world. Diagnosis of periodontal disease was once dependent upon clinical examination using periodontal probe and dental radiographs as an adjunct.  Radiographs are indispensable for showing concealed anatomic structures such as the alveolar bone. They reveal the extent of interdental and interradicular bone loss, root length, periodontal ligament space, and any apical changes in the tooth. 
|How to cite this URL:|
Pahwa P, Lamba AK, Grewal H, Faraz F, Tandon S, Yadav N. Evaluation of two-dimensional and three-dimensional radiography with direct surgical assessment of periodontal osseous defects: A clinical Study. Indian J Dent Res [serial online] 2014 [cited 2019 Aug 18];25:783-7. Available from: http://www.ijdr.in/text.asp?2014/25/6/783/152205
However, radiographs give a two-dimensional (2D) representation of three-dimensional (3D) structures. Many complicated anatomic structures, such as cortical plates or teeth, may superimpose the region of interest (ROI). Foreshortening or elongation of radiographic images caused by cone indication and variations in the contrast and density caused by poor control of film processing, may prevent the accurate detection of osseous changes by the clinician. ,
To overcome these difficulties, 3D image analysis using computed tomography (CT) has been introduced in the oral and maxillofacial surgery field. It has the potential to allow precise assessment of bone defect (BD) caused by periodontal disease.  It can show the structures in axial images, summation of which facilitates the interpretation of the structures in 3D.
Previous research work had compared intra oral periapical radiographs and orthopantograms using digitized images with direct surgical measurements, but none of them had compared the CT scan with the conventional radiographs in diagnostic assessment of periodontal osseous defects.
The aim of the present study is the comparative evaluation between radiovisiograph (RVG) and CT images to the intrasurgical method that served as the study's gold standard in measuring periodontal osseous destruction. In addition, the null hypothesis stated that there are no differences in accuracy between RVG and CT techniques relative to direct surgical measurement when accuracy is defined as the difference between the radiographic technique and direct surgical measurement.
| Materials and methods|| |
Fifteen patients (10 female and 5 male) aged 20-54 years (mean 38 years) participated in the study between Jan 2009 and Feb 2010. The study was conducted at Department of Periodontics and Oral Implantology, Maulana Azad Institute of Dental Sciences, New Delhi, India.
The inclusion criteria were a diagnosis of generalized moderate to severe chronic periodontitis with at least one inter proximal site with a minimum of 3 mm of clinical attachment loss according to American Academy of Periodontology 1999 classification workshop. Each defect was the unit of analysis in the present study. Total of 31 vertical defects were available for comparison between direct surgical measurements and radiographic measurements from the selected sample. All patients were informed about the aim of the study, radiation risks, benefits of treatment, alternative treatment options and signed an informed consent approved by the Institutional Review Board and Ethical Committee. At the beginning of the study, the patients were subjected to a baseline examination during which the following parameters were assessed; pocket probing depths and probing attachment levels. Subsequent to the initial examination, patients received the hygiene phase of therapy. This phase consisted of oral hygiene instruction, scaling and root planning, and occlusal adjustment when indicated. Radiographic investigations were carried out before scheduling the subjects for surgical intervention.
Radiovisiograph was obtained using the long-cone paralleling technique in a standardized exposure set-up with a size 1 charged coupled device sensor (Kodak RVG 5000, Eastman Kodak, Rochester, NY, USA) and a direct current X-ray unit (Trophy Intra-Oral X-Ray Unit Irix 70, Trophy Radiologie, UK). A rectangular collimator and film-holding system were used (XCP-DS® , Dentsply Rinn, Elgin, IL, USA). The focal-film distance was 40 cm. The exposure setting was 70 kVp with 8 mAs [Figure 1].
|Figure 1: Radiovisiograph image of an intrabony defect associated with the mesial aspect of tooth #36 (mandibular left first molar)|
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Computed tomography scans were obtained with a gantry inclination of 0°, a reconstruction matrix of 512 × 512 pixels, a slice thickness of 1 mm. The tube voltage was 120 kV, the tube current 100 mA, and the exposure time 1.5 s/slice (HiSpeed Dual, GE Healthcare, IL, USA). The original CT data, stored on optical disks to allow full retrospective review of any image, was transferred to a networked computer workstation (GE Advantage Workstation, GE Healthcare, IL, USA), to generate 3D volumetric images for visualization, manipulation and analysis [Figure 2].
|Figure 2: Computed tomography scan-panoramic section showing intrabony defect|
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Following the acquisition of both 2D and 3D radiographs, the selected sites were administered local anesthesia, incisions were placed and flaps were reflected [Figure 3]. Thorough removal of the granulation tissue from the BDs was done and intrasurgical measurements performed with manual 15-mm periodontal probe (University of North Carolina-15, Hu-Friedy, Chicago, IL, USA). Under complete visual control, probing to bone contact of the proximal marginal bone was done to the nearest millimeter. The cemento-enamel junction (CEJ) or the base of an existing restoration was used as the fixed reference point. Measurements included determination of alveolar bone level that is, distance from CEJ to base of the BD (CEJ-BD) and from CEJ to the alveolar crest (CEJ-AC). Infrabony component was measured by subtracting (CEJ-AC) from (CEJ-BD). The linear measurements were performed at line angle of the tooth at sites where highest value could be measured either labially/bucally or palatally/lingually.  The soft tissue flap was then repositioned at the original level and closed with interrupted sutures using 3-0 silk (Mersilk® Silk Suture, Ethicon, USA). All clinical measurements were made by single clinician (PP).
The analysis of the images was blinded, and all radiographic measurements were made by single investigator (AKL). Periodontal defects were studied and measured on a 14-inch, 1280 × 800 pixel resolution liquid crystal display computer screen by examiner seated approximately 60-100 cm from the monitor (VAIO® Computer, Sony Electronics Inc., USA). Images were viewed under subdued lighting conditions.
Linear measurements were recorded on the radiographic image acquired from three modalities. (1) Alveolar bone level-distance from CEJ-BD. Base of defect (BD) was taken as a point at which the periodontal ligament space is no longer uniform.  (2) Distance from CEJ-AC. AC was considered to be the most cervical level along the proximal root surface, where the periodontal ligament started to be of equal width.  (3) Infrabony component was measured by subtracting (CEJ-AC) from (CEJ-BD).
Measurements on the CT software (GE Centricity DICOM Viewer V3.0, GE Healthcare Integrated IT Solutions, IL, USA) were carried out on a panoramic reconstruction view. Different slices of CT images were sequentially analyzed to locate the most apical point of the BD, the most coronal aspect of the defect-associated AC. Each slice was analyzed for the separate measures, because the extreme points for BD and AC were usually located in two different slices.
Linear measurements of the BDs for both RVG were rounded off to the nearest 0.1 mm, whereas CT images were measured to the nearest 0.01 mm.
The data were tested for normal distribution by Shaprio Wilks and found normal for all the variables. Absolute agreement between surgical method (gold standard) and the radiographic modalities for vertical defects was obtained using intra class correlation coefficients (ICCs). About 95% confidence interval (CI) was calculated for ICC. The two-way mixed model analysis of variance was used to estimate the ICCs. ICC more than 0.80 was considered to be good measure of agreement. P < 0.05 was set as significant.
Limits of agreement by Bland and Altman method (mean of difference ±1.96* standard deviation of difference) for vertical defects was obtained. The number and percentage of sites with overestimations/underestimations as compared to surgical method were calculated. All statistical analyses were done using statistical software (SPSS version 15.0, SPSS Inc., IBM, Chicago, IL, USA).
| Results|| |
Radiovisiograph and CT scan showed mean difference (in mm) of 0.645 ± 0.557 and 0.070 ± 0.144 respectively for vertical defects, which were statistically significant (P < 0.001) as compared to the surgical value [Table 1].
Intra class correlation coefficients of RVG and CT scan were more than 0.8 but the CI of RVG was wider thereby showing less reliability in the agreement. CT scan's ICC (0.997) was highest, and 95% CI (0.998-0.999) had the smallest length in relation to the surgical values.
Computed tomography scan (−0.218, +0.358) showed maximum agreement with the surgical value in comparison with the 2D radiograph.
Radiovisiograph presented with greater mean difference (in mm) of 0.226 ± 0.529 as compared to CT scan (0.066 ± 0.175). ICC of RVG (0.900) was less than CT scan (0.990). On the other hand, CT scan had smallest length of 95% CI (0.978-0.995) and maximum agreement with the surgical value in comparison with RVG [Table 2].
In vertical defects [Table 3], the maximum percentage of sites in RVG (96.8%) showed underestimation except the CT scan (71.0%) that overestimated in the maximum percentage of sites. In infrabony component (vertical defects), RVG (58.1) and CT scan (51.6%) showed comparatively equal distribution.
Radiovisiograph underestimated the surgical values in vertical defects and infrabony component. But the CT scan had a variable distribution in evaluation of the osseous defects. It underestimated the infrabony component but showed overestimation of the vertical defects.
|Table 3: Underestimation/overestimation with surgical method by RVG and CT Scan|
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| Discussion|| |
Intraoral radiographs are the most conventional imaging techniques used in dental practice in spite of their emphasized limitations and questioned role in diagnostic value. , The 2-D mapping of an intraoral region on a periapical radiograph is always very susceptible to angulation errors, , 3D CT technique came into scenario to encounter these problems. Their images are an assembly of digitized numbers called Hounsfield units which can be easily determined in the ROI by the built-in CT software.  The mesio-distal and bucco-lingual dimension are easily identified on CT so that all infra alveolar bony defects can be arranged according to the number of surrounding bony walls into one, two and three-walled bony defects. 
Previous studies using 3D CT technique for comparison with 2D radiography in assessment of periodontal osseous defects were performed in-vitro on standardized preparation of periodontal defects in human mandibles.  Due to the presence of clear and precise border of prepared defects and better geometric alignment of dry human skulls, more precision was advocated in the sensitivity of their detection. But they cannot simulate the remarkably different in-vivo conditions which are required for the diagnostic validity of periodontal osseous defects. The limitation was overcome in this study by conducting an evaluation of osseous defects in-vivo during the open flap debridement.
The results of the present study show that CT scan had the least mean difference (0.073) when compared with 2D (RVG) radiograph in vertical defects and infrabony component. These observations were in accordance with the study done by Mengel et al.  where he observed greatest deviations in the cranio-caudal measurements in the intraoral radiography. Similarly Pepelassi and Diamartti-Kipioti  observed statistically significant difference between the assessment of osseous destruction by periapical (1.20 mm) as compared to surgical assessment. Difference between intrasurgical and intraoral radiographic measurements was in addition proved to be statistically significant by Tonetti et al. 
Significant improvement in the evaluation of alveolar bony defects by CT scan and negligible difference between the CT and actual readings was due to the accuracy in reproducibility of, presence or absence of buccal and lingual cortical plate. 
Intra class correlation coefficient of CT scan was comparatively higher than RVG in evaluation of defect depth. In addition, the 95% CI for ICC values were considerably narrower for CT scan measurements, suggesting that data gathered from CT scan images more accurately reflect bony defect dimensions than from 2D (RVG) images.
Fuhrmann et al.  observed likewise the correlation coefficient of CT scan to be in better agreement with jaw specimen findings than the dental radiographs. Improved agreement of CT Scan with the histological specimens in relation to the panoramic and intraoral radiography was also proven. 
The sites that were evaluated for osseous defects showed underestimation in measurement with RVG. This was due to the limitation of 2D radiography in precisely locating the base of the defect due to increased overlapping of bony walls and presence of cancellous bone at the base of the defect.
Computed tomography scan similarly showed underestimation in the maximum percentage of sites, while detecting osseous destruction in infrabony component.
These results were consistent with those of Katagiri et al.,  Tonetti et al.,  Eickholz and Hausmann,  Zybutz et al.  who mostly found underestimation of recordings from radiographs.
On the contrary, CT scan had the tendency to overestimate the depth in vertical osseous defects (71.0%), due to the assessment of the AC and base of the defect performed from different oblique sections reconstructed from the axial images.
| Conclusion|| |
Computed tomography scan provides a more explicit and clinically useful 3D image of the osseous defects (horizontal defects, vertical defects and infrabony component), revolutionizing the diagnosis of periodontal diseases. It lends a helping hand to the clinician right from diagnosis until the definitive treatment of the condition. The added advantage with 3D CT modality is the elimination of the need of surgical re-entry in order to confirm the augmentation in bone levels after bone regeneration procedures.
Before this imaging modality becomes integrated within the routine practice, a few areas of concerns need to be explored in greater depth like increased levels of exposure to radiation regarding health and safety issues compared to its added benefits of diagnosis, as well as an additional cost raising the bills of dental treatment. Another area of concern is the ethical issue of preventing the unnecessary over prescription of this imaging modality, thus making it relevant to clearly define its objectives of usage and significance in different clinical situations.
Although CT scan can improve diagnosis and reduce the need for unnecessary exploratory surgeries or other invasive examinations, demonstrate response to treatments, caution needs to be exercised in their potential overuse. CT scans are increasingly being used as a standard investigation, replacing other conventional ways of detecting health problems that are a matter of concern. The potential risks related to radiation-immediate direct damage to body tissues, carcinogenic effect need to be addressed. More so because there is uncertainty about the level of risk from radiation from CT scans. The risk is influenced by many factors, including age and size, the part of the body being scanned, number of scans given and radiation dose, and the radiosensitivity and genetic susceptibility of the individual. Radiation exposures for patients must be justified that is, exposure should produce sufficient benefit to the exposed individual to outweigh the potential risk of exposing to radiation and optimized that is, procedures and techniques should keep radiation exposures as low as reasonably practical.
Further studies and research employing low dose radiographic modalities with high resolution are required to assess the role of 3D radiography especially CT scan as well as its other alternatives in the diagnosis and treatment planning of periodontal disease so that they can prove as novel tools opening new gates of opportunities for clinicians globally.
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Department of Periodontics and Oral Implantology, Maulana Azad Institute of Dental Sciences, New Delhi
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]
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