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Year : 2016  |  Volume : 34  |  Issue : 4  |  Page : 300-305

Diagnostic accuracy of direct digital radiography and conventional radiography for proximal caries detection in primary teeth: A systematic review

Department of Pedodontics and Preventive Dentistry, Narayana Dental College and Hospital, Nellore, Andhra Pradesh, India

Date of Web Publication29-Sep-2016

Correspondence Address:
Sreekanth Kumar Mallineni
Department of Pedodontics and Preventive Dentistry, Narayana Dental College and Hospital, Nellore - 524 003, Andhra Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-4388.191406

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Objective: The present study was conducted to uncover the diagnostic accuracy of digital versus conventional radiographic methods for the detection of proximal caries in primary teeth. Methods: Two researchers independently involved in the search process to explore Medical Subject Heading terms "dental digital radiography," "dental radiography," "bitewing," "dental caries," and "primary teeth" using PubMed, Cochrane Library, Ovid SP, and SIGLE databases. Search was confined to the articles published in English language only, with time period limit January 1996 to April 2014 and a hand search was performed to retrieve additional citations. Explicit inclusion and exclusion criteria were applied to eliminate undesired studies. Critical appraisal of the retrieved articles was done using the quality rating based on Bader and co-workers criteria. Results: A total of 129 articles were retrieved, among which 4 articles were included. All the four studies included were in vitro, of which two studies attained a high-quality score, whereas the other two attained average, and low scores based on Bader et al.'s criteria. Conclusions: A big lacuna exists in the literature, regarding the evaluation of radiographic systems in primary teeth, suggesting an immediate need for well conducted in vivo studies. The quality of available evidence can be regarded as fair but cannot be suggested to set a baseline, indicating a need to perform high-quality studies in a randomized sample to find out the accuracy of digital and conventional radiographs.

Keywords: Dental caries, dental radiography, digital radiography, primary dentition

How to cite this article:
Nuvvula S, Bhumireddy JR, Kamatham R, Mallineni SK. Diagnostic accuracy of direct digital radiography and conventional radiography for proximal caries detection in primary teeth: A systematic review. J Indian Soc Pedod Prev Dent 2016;34:300-5

How to cite this URL:
Nuvvula S, Bhumireddy JR, Kamatham R, Mallineni SK. Diagnostic accuracy of direct digital radiography and conventional radiography for proximal caries detection in primary teeth: A systematic review. J Indian Soc Pedod Prev Dent [serial online] 2016 [cited 2022 Dec 5];34:300-5. Available from: http://www.jisppd.com/text.asp?2016/34/4/300/191406

   Introduction Top

Dental caries is a disease process of tooth that escapes early detection during clinical examination, particularly on the proximal surfaces. [1] Primary teeth are at a major risk of developing dental caries with earlier progression into dentin than permanent teeth, due to broader contacts, and thinner and porous enamel. [2],[3],[4] Detection of early carious lesions on the proximal surfaces of closed primary dentition requires skill and experience, while radiographs are also important diagnostic tools in such cases. [5],[6],[7]] Nonetheless, accurate caries detection is essential for the management and preservation of the integrity of primary dentition.

Although many routine and new caries detection methods exist, none of these methods in isolation would give an accurate detection of caries lesions with appropriate sensitivity and specificity on all dental surfaces. Radiography remains a routine method for the detection of caries lesions. [8],[9] The selection of obvious radiograph for caries detection is always questionable. In the recent years, digital radiography (DR) has been introduced and compared with conventional film-based system. A few studies have shown that the image quality of conventional radiographs (CR) was comparable to DR (charged couple device [CCD] [10] and phosphor plate system). [11],[12] Conversely, subsequent researchers reported better accuracy of conventional system over DR, [13] whereas few other researchers reported superior accuracy of storage phosphor plate (SPP) systems over CR and CCD. [14],[15],[16],[17] Radiographic examination of primary teeth had received comparatively less attention than the permanent teeth; [18] however, diagnostic accuracy of radiographs in the primary teeth was considered to be superior. [19] This has been questioned because inclusion of more cavitated teeth in the study sample merely increases the performance. [18] Hence, the dilemma still continues and there is insufficient evidence to support the better accuracy of DR over CR for caries detection in primary teeth.

The aim of the present systematic review is to discern the available literature on DR versus CR on primary teeth and uncover the diagnostic accuracy of them in detecting approximal caries. The hypothesis of present study was that DR has better accuracy than the CR for proximal caries detection in primary teeth.

   Methods Top

A detailed database search was conducted using Medical Subject Heading terms [Table 1] corresponding to PICO format in PubMed, Cochrane Library, and Ovid SP. The search words included digital radiograph */radiovisiography, dental radiograph*/bitewing, caries/cavit*, and deciduous/primary teeth in various combinations. The search was restricted to articles published in English language with time period limit January 1996 to April 2014. In addition, gray literature database SIGLE (theses, dissertations, product reports, and unpublished studies) and cross references of relevant articles were probed but no efforts were made to contact authors. Besides, hand searching was completed based on the cross-referencing and citations of the retrieved data. Two researchers have participated in the search process and appraisal of retrieved articles.
Table 1: Medical Subject Heading terms and alternate terms enclosed in search strategy

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Inclusion criteria

  • In vitro /in vivo studies on proximal caries detection comparing the conventional and DR
  • Studies on radiography reporting diagnostic accuracy, i.e. sensitivity, specificity, and receiver operating characteristic curves
  • Studies on primary teeth validated with reference/gold standard
  • Studies published in English language only during January 1996 to April 2014.

Exclusion criteria

  • Studies with incomplete description of the sample size or outcome
  • Studies reporting accuracy in permanent teeth exclusively
  • Studies included suspicious surfaces only for histological validation
  • Studies in which exploratory surgical intervention was employed to confirm positive diagnosis
  • Animal studies, review articles, letters to editor, and conference abstracts.

A quality score for the included studies using quality rating criteria covering 11 elements of internal validity [20] was computed [Table 2]. The elements included are sample size, selection of teeth and surfaces, setting, validation method, validation criteria, validation reliability, lesion prevalence, number of examiners, examiner reliability, and lesion criteria. The quality scores ranged from 0 to 20, which were rescaled to a 0-100 scale.
Table 2: Quality rating criteria used to assess the internal validity of studies[20]

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   Results Top

A total of 126 articles were retrieved from three databases (PubMed-58, Cochrane Library-5, and Ovid SP-63), of which 13 articles sustained title and abstract review, from which 9 articles were excluded following full-text review, and 4 articles were included for final methodological appraisal [Figure 1]. A total of 122 articles were excluded due to the following reasons: Abstracts not available, irrelevant studies, review articles, and letters to editor. Search in gray literature database SIGLE and hand search yielded no relevant citations. The details related to quality rating of articles included in the study were summarized in [Table 3]. High quality was defined as rescaled score at or above 60, and average quality was defined as rescaled score at or above 45. The reviewers assigned the quality of the studies with 90% agreement, and the disagreements were reached through consensus.
Figure 1: Flow diagram representing comprehensive search process with identification, inclusion, and exclusion of studies

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Table 3: Overview of included studies with summary of elements of internal validity assessed

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Results from a comprehensive search strategy revealed that there were very few studies comparing the performance of CR with digital radiographic images in primary teeth. Moreover, the quality score of two studies [21],[22] was equal to 60 considered as high and for the other two studies [23],[24] with <60 were considered as low (score 35) and average (score 55). None of the studies used randomization procedure to avoid selection bias. No randomized controlled trials were performed till to date to assess diagnostic accuracy of DR and CR in primary teeth.

   Discussion Top

The diagnostic accuracy and applicability of commonly used methods require a comprehensive research to discern the advantages, limitations, and further improvements to be achieved in the interest of the patients and dentists. This stimulated us to undertake this research. All the retrieved studies were in vitro, which further limits the detection of caries lesions in clinical settings. Any in vitro study should simulate clinical scenario, [25] such as placing the digital receptor or films of varied sizes in an artificially created oral environment, with appropriate dimensions related to different age groups. Furthermore, proving the diagnostic accuracy of imaging method, which does not perfectly suit to the patients, is a mere compromise. For instance, the solid state sensors are bulky, cannot be tolerated by a child, and usually misses the distal surface of canine and the mesial surface of first primary molar during bitewing examination. [26] Another major drawback with in vitro studies is the validation method used. Currently, histological assessment is considered as gold standard, which is far from the ideal and practical. [25] In addition, the presence/absence/extent of caries in the in vivo studies is justified by clinical examination or operative caries removal which itself is inherently biased. [27] There is an enormous need to develop an appropriate reference standard that suits the in vivo studies.

Randomized controlled trials with clinical reference standard using operating microscope or surgical loupes are the possible methodological alternatives in clinical settings. None of these reported studies have performed power analysis for the selection of the study sample. Caries prevalence in the selected sample of teeth, specific to a surface also poses limitations, since caries status of selected teeth should represent the respective population in which the diagnostic system would be studied. [25] Ideally, the diagnostic system should identify the disease in hidden form or magnitude in low prevalence areas such that it aids the clinician in proper diagnosis and management. The diagnostic accuracy in all the studies included for this review was represented with receiver operating characteristic analysis without reporting the sensitivity and specificity.

Nielsen et al. [24] compared SPP versus E-speed film with the teeth tested consisted of sound to small cavitations (calculated caries prevalence of 45.8% from the sample), which needs to underpin the diagnostic ability of early disease rather than the obvious large cavitations. However, the actual disease spectrum in the respective population has not been taken into account. The visual examination of unmounted teeth with the probe used as validation/gold standard method is a biased procedure. The intra- and inter-rater reliability statistics were not reported, and the sample size was not predetermined, which reduces the strength of study.

Uprichard et al. [23] evaluated the diagnostic accuracy of D (Ultra) and E (Ekta) speed films with CCD. Researchers have selected a sample with random mix of caries free molars, which helped in testing the specificity of the diagnostic regimen. There is no clarity regarding the number of teeth with dental caries, posing a limitation in the calculation of disease prevalence. Preliminary calibration of the image density at various exposure times and the number of examiners involved in the image interpretation are the advantages of this study. The intra- and inter-examiner reliability of histological examination and inter-examiner reliability for the radiographic image analysis were not reported, which increases the unknown risk of bias.

Ulusu et al. [22] assessed the diagnostic efficacy of a handheld wireless unit compared to E-speed film. The tested nonpredetermined sample consists of equal proportions of carious and noncarious teeth. The calculated caries prevalence in the sample ranged up to 61.1%, which indicates the biased performance of diagnostic system in the detection of obvious disease rather than assisting the detection of hidden lesions. Preliminary image calibration with the new device was not carried out and reliability statistics, criteria used to classify the extent of disease during validation procedure were not mentioned.

Sogur et al. [21] studied the effect of various tube potentials on the detection of proximal caries using E-speed film, SPP, CCD, and recommended SPP system at 50 kVp for children due to better caries detection. Although this study tested the accuracy at 50, 65, and 70 kVp tube potentials, the images evaluated at 65 kVp were considered for critical appraisal as most of the studies conducted were at 65-70 kVp tube potentials and this range also represent the clinical scenario. The calculated caries prevalence from the sample was 62.3%, which shows that the performance of diagnostic system tested was not appropriate.

Although the digital systems have few disadvantages (difficulty in positioning sensors, retakes, high cost), the advantages such as fewer errors in image, better patient (dose reduction) and clinician compliance (dynamic image, time saving, image storing, and easy communication), as well as ecofriendly (no processing chemicals) which make them suitable for usage in the clinical setup. [28] Moreover, digital sensors are difficult to place in the child's mouth and might frighten the children, whereas conventional bitewings cause less discomfort than the sensors. In addition, there is not much difference between the implementation costs of conventional and DR for a practitioner who is opening a new practice. Nevertheless, maintenance costs are less with digital imaging. [29] This review has some limitations, i.e., it is a focused review and has considered the performance of digital systems only in primary teeth with search performed in only three databases and the hand searching was limited. However, the comprehensiveness of search strategy performed in those three main databases would have increased the sensitivity and surpassed the above limitation.

   Conclusions Top

A big lacuna exists in the literature, regarding the evaluation of radiographic systems for the detection of proximal caries in primary teeth. All the reported studies were conducted in vitro; hence, the quality of the available evidence is fair. There is an immediate need for in vivo studies regarding the evaluation of various digital systems and conventional systems in terms of diagnostic accuracy of proximal carious lesions.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

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  [Table 1], [Table 2], [Table 3]

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