Accuracy of dental images for the diagnosis of dental caries and enamel defects in children and adolescents: A systematic review

Abstract

Aim

The aim of this review was to determine if photographic examination and subsequent image analysis provides comparable accuracy to visual inspection for the diagnosis of common dental conditions in children and adolescents.

Methods

We searched the PubMed database for studies that compared diagnostic accuracy of the two inspection techniques. Studies were screened for inclusion and were assessed for quality and risk of bias using the quality assessment of diagnostic accuracy studies tools. Findings were reported according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA).

Findings

Sixteen studies met the inclusion criteria. Nine of the included studies evaluated dental caries and eight evaluated enamel defects (one study evaluated both conditions).

Conclusions

Three studies found image analysis to be superior. For the remaining six studies the diagnostic accuracy was comparable. For enamel defects, three studies found image analysis to be superior, two found visual inspection to be superior and three studies reported comparable diagnostic accuracy. Most studies have found at least comparable results between photographic and visual inspection techniques. However, the wide variation in equipment and personnel used for the collection and interpretation of photographic images made it impossible to generalise the results. It remains unclear exactly how effective store-and-forward teledentistry is for the diagnosis of common dental conditions in children.

Keywords

Remote consultation telehealth

Introduction

The World Health Organization regards school children and adolescents as an important target group for priority actions in oral health.¹ The burden of oral disease in these age groups is significant and early diagnosis is important for the prevention of the disease’s progress. For people living in remote areas of Australia it is much more difficult to access dental services, given that the majority of dental services are located in city areas. The number of dentists available per head of population, when comparing remote communities with metropolitan areas, is about one-third.²

Visual inspection is the most common technique to diagnose caries and enamel defects in clinical practice.^3,4 Remote diagnosis using transmitted photographic images of dentition (teledentistry) may be an alternative to visual inspection, particularly for people living in remote and underserved areas.^5–10 However, the photographic images used in an asynchronous mode are two-dimensional and this characteristic may affect their diagnostic accuracy.

To the best of our knowledge there has been no previous attempt to review available literature that compares the accuracy of in person visual inspection versus photographic image analysis. The aim of this review was to determine if photographic examination and subsequent image analysis provides comparable accuracy to visual inspection for the diagnosis of common dental conditions in children and adolescents.

Methods

Search strategy

We searched the PubMed database for peer-reviewed literature using a combination of medical subject headings (MeSH) terms and key words. The syntax of the two queries used for the searches are shown in Table 1. Searches were conducted in February 2015. The references of eligible papers were searched manually by one reviewer to identify potential studies not identified by the database searches.

Table 1.

Search strategy.

Search	Syntax
1	dentistry[MeSH Terms] AND (intraoral photography[MeSH Terms] OR ‘photography, dental’[MeSH Terms]) AND (dental caries[MeSH Terms] OR dental enamel[MeSH Terms] OR Tooth Wear[MeSH Terms] OR Dental Fluorosis[MeSH Terms] OR Dental Enamel Hypoplasia[MeSH Terms])
2	teledentistry[Title/Abstract] OR (telemedicine[MeSH Terms] AND Dentistry[MeSH Terms])

Eligibility criteria

Studies were included if they compared the diagnosis from images (photographic, video or intraoral camera) to visual inspection for dental diseases common in the target population. Studies in languages other than English or with no abstract available were excluded.

Study selection

Two reviewers independently examined the titles and abstracts to determine eligibility for inclusion. Selected papers were then compared and discrepancies were resolved by consensus discussion.

Data collection and quality assessment

The full texts of studies meeting the inclusion criteria were obtained and data extracted. One reviewer extracted data from the full text. A second reviewer independently verified the extract. A form was used to record extracted data. The form included: year of publication, location, sample size, disease, index used to classify the disease, equipment used to obtain the images (digital camera, intraoral camera or video camera) and imaging protocol.

The revised quality assessment of diagnostic accuracy studies (QUADAS-2) tool¹¹ was used to assess the risk of bias and applicability of the included studies. We defined the visual inspection as the reference standard. The QUADAS-2 tool must be tailored to each review. Table 2 lists the signalling questions that were added during tailoring of the QUADAS-2 tool for our review.

Table 2.

The QUADAS-2 tool tailored to this review.

Domain	Signalling questions
Case selection		Was a consecutive or random sample of patients enrolled?
		Was a case-control design avoided?
		Did the study avoid inappropriate exclusions?
	+	Was a range of disease severity included in the study?
	+	Did the study avoided settings with high disease prevalence?
	+	Is there an appropriate sample size?
Index test	+	Was the scale on the instrument used to record reader diagnosis descriptive, ordinal or continuous? I.e. not binary or dichotomous.
	+	Was conduct of the aspect of the index test done not to distort results?
	+	Are the examiners representative of a dentist population?
	+	Did the display of images (resolution, size of display, effect of ambient lighting, medium) avoid distorting the results?
	+	Were all index test outcomes reported?
	+	Did the photographic examination evaluate all of the teeth and/or surfaces, as did the visual inspection?
Reference standard		Is the reference standard likely to correctly classify the target condition?
	+	Were the reference standard examiners calibrated?
	+	Did the clinical examination evaluate all appropriate teeth and/or surfaces?
	+	Was the reference test diagnosis validated (by use of experts/multiple examiners)?
Flow and timing		Was there an appropriate interval between index test(s) and reference standard?
		Did all patients/teeth receive (be evaluated by) a reference standard?
		Did all patients/teeth receive (be evaluated by) the same reference standard?
		Were all patients/teeth included in the analysis?

QUADAS-2: quality assessment of diagnostic accuracy studies; +: added signalling question

Synthesis of results was performed narratively. Reporting of the findings of this review followed the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guideline.¹²

Results

We identified 16 studies that met inclusion criteria. Figure 1 represents the study selection process.

Figure 1.

PRISMA flow-chart.

Study characteristics

Publication years ranged from 1998 to 2014. The studies were conducted in North America (n = 4), Latin America (n = 2), Europe (n = 8) and Asia (n = 1). A further study was conducted by a multi-national group. The oral diseases evaluated were: dental caries (n = 10), enamel developmental defects (n = 3), fluorosis (n = 3) and erosion (n = 1). One study evaluated both dental caries and enamel developmental defects. Twelve of the studies (75%) were performed in vivo and four (25%) in vitro (Table 3). All in vitro studies were related to dental caries diagnosis. Only one study evaluated adolescents and the studies that evaluated children showed a wide range in age groups (Table 3). Different disease indexes were used to classify dental caries and fluorosis, including some developed by the authors on included studies. The only index used consistently was that used to classify developmental defects of enamel (DDE).

Table 3.

Study characteristics.

Authors	Disease	Disease classification index	Category of experiment	Age range	Teeth/surface	Sample size	Equipment	Type of image
Forgie et al., 2003 ¹ ³	Dental caries	Scoring system developed by the authors	In vitro	NR	Occlusal surfaces of permanent molars, premolars and canines	n = 80	Intraoral camera, video (Clear-Vu, Dental Practice Systems)	Moving image
Erten et al., 2005 ¹ ⁴	Dental caries	ERK scale¹⁵	In vitro	NR	Occlusal surfaces of permanent molars and premolars	n = 84	Intraoral camera (Rydalmere)	Moving image
Boye et al., 2012 ¹⁶	Dental caries	BASCD	In vitro	NR	Occlusal surfaces of permanent molars and premolars	n = 50	Intraoral camera (Sopro 717, The Acteon Group®)	Still image
Gomez et al., 2013 ¹⁷	Dental caries	ICDAS	In vitro	NR	Occlusal surfaces of permanent molars and premolars	n = 120	Intraoral camera (SoproLife® camera)	Still image
Patterson and Botchway, 1998 ¹⁸	Dental caries	deft/DMFT (e = to be extracted)	In vivo	Children (no information about ages)	All visible surfaces of all present (primary and permanent) teeth	n = 27 (pilot study)	Intraoral camera, video (Revealr system, Patterson Dental)	Still image
Kopycka-Kedzierawski et al., 2007 ¹⁹	Dental caries	dfs	In vivo	Children 4–5 years old	All visible surfaces of all primary (deciduous) teeth	n = 50	Intraoral camera (Dr. Camscope, Sometech Inc.)	Still image
Boye et al., 2013 ²⁰	Dental caries	DMFT/dft	In vivo	Children 5 and 10–11 years old	All visible surfaces of all primary (deciduous) teeth (5yo) OR erupted permanent teeth (10–11yo)	n = 270	Intraoral camera (Sopro 717, The Acteon Group®)	Still image
Morosini et al., 2014 ¹⁰	Dental caries	DMFT	In vivo	Adolescents 15–19 years old	All visible surfaces of all permanent teeth	n = 102	Digital SLR camera (EOS 300 Rebel w/ macro lens and ring flash)	Still image
Elfrink et al., 2009 ²¹	Dental caries and PMH	Caries: dft PMH: scoring criteria adapted from EAPD	In vivo	Children 3–7 years old	Primary (deciduous) molars (caries) OR second primary molars (PMH)	n = 62	Intraoral camera (Poscam, Digital Leader PointNix)	Still image
Wong et al., 2005 ²²	DDE	Modified DDE Index	In vivo	Children 10–12 years old	Buccal surfaces of maxillary and mandibular permanent canines and incisors (central and lateral)	n = 257	Film based SLR camera (Nikon F2 w/ macrolens and ring flash)	Still image (transparencies)
Golkari et al., 2011 ² ³	DDE	Modified DDE index	In vivo	Children 8–10 years old	Buccal surface of maxillary and mandibular permanent incisors (central and lateral)	n = 90	Digital SLR camera (Nikon D80 w/ macro lens and macro double flash)	Still image
Chen et al., 2013 ² ⁴	DDE	Modified DDE index	In vivo	Infants 8–20 months old	Buccal surface of anterior primary (deciduous) teeth (canines, central and lateral incisors)	n = 376	Digital SLR camera (Canon EOS Rebel T2i 550D w/ macro lens and ring flash)	Still image
Tabari et al., 2000 ²⁵	Fluorosis	TF index	In vivo	Children 8–9 years old	Buccal surfaces of the maxillary central permanent incisors	n = 812	Film based SLR camera (Nikon F 90 w/ macro lens and ring flash)	Still image (transparencies)
Martins et al., 2009 ²⁶	Fluorosis	(N/A)	In vivo	Children 7–9 years old	Buccal surfaces of the maxillary and mandibular central permanent incisors	n = 49	Digital Still camera (Mavica CD500, Sony Eletronics Inc.)	Still image (printed photographs)
Cruz-Orcutt et al., 2012 ²⁷	Fluorosis	Fluorosis index risk	In vivo	Children 13 years old	Buccal surface of the maxillary central and lateral permanent incisor teeth	n = 538	Digital camera (Nikon digital camera w/ macro lens, automatic flash)	Still image
Al-Malik et al., 2001 ²⁸	Tooth wear (erosion)	Scoring system developed by the authors	In vivo	Children 2–5 years old	Maxillary primary (deciduous) incisors (buccal and palatal surfaces)	n = 727	Film based SLR camera (Nikon F-601 w/ macro lens and ring flash)	Still image (transparencies)

DDE: developmental defects of enamel; PMH: primary molar hypomineralisation; BASCD: British Association for the study of Community Dentistry; ICDAS: International Caries Detection and Assessment System; N/A: not applicable; SLR: single-lens reflex; DMFT: decayed, missing, filled teeth (permanent); deft index: decayed, to be extracted, filled teeth (deciduous); dfs: decayed, filled surfaces; dft: decayed, filled teeth; EAPD: European Association of Paediatric Dentistry; TF: Thylstrup–Fejerskov; NR: Not reported

The type of equipment used to acquire the images showed great variation, including different intraoral cameras, photographic cameras (some film based) and video cameras (Table 3). The information about the imaging equipment used was not provided in one study. The imaging protocol for photographic cameras (frequently used with macro lens and ring flash) was largely consistent, whereas the imaging protocols for intraoral cameras were not consistent.

The professional background of the person that acquired the images was not clearly identified in most of the studies. It was possible to infer that they were either a dentist (n = 9) or a dental hygienist (n = 1). In the studies that explicitly stated the professional background of the photographer (n = 4), three were dentists and one was a trained telehealth assistant.

Comparative diagnostic accuracy

Nine of the included studies evaluated dental caries. Three studies^13,14,19 found image analysis to be superior to visual inspection, one study found visual inspection superior¹⁶ and in the remaining five studies^{10,17,18,20,21} the diagnostic accuracy from both inspection techniques was comparable. Comparable diagnostic accuracy of occlusal caries was found to be the most consistently reported finding.

Eight studies evaluated the following enamel defects: DDE (n = 3); fluorosis (n = 3); primary molar hypomineralisation (PMH) (n = 1) and erosion (n = 1). For DDE, two studies considered image analysis better than visual inspection and one found the diagnostic accuracy to be equivalent for the two techniques. There was no consensus for fluorosis as one study found superior diagnostic accuracy from image analysis, one study diagnosis from visual inspection and one reported similar diagnostic accuracy for the two inspection techniques. The one study that investigated PMH had equivalent diagnostic accuracy for both inspection techniques. The one study that investigated erosion found superior diagnostic accuracy for visual inspection. Results for each study are reported in Table 4.

Table 4.

Study results.

Authors	Focus	Face-to-face (visual inspection)	Teledentistry (image inspection)	Favours
Forgie et al., 2003 ¹ ³	Dental caries – enamel and dentine lesion Dental caries extending into dentine	Sensitivity 43.0% Specificity 91.7% Sensitivity 26.8% Specificity 96.6%	Sensitivity 68.2% Specificity 63.8% Sensitivity 41.5% Specificity 98.6 %	Teledentistry
Erten et al., 2005 ¹ ⁴	Dental caries	Sensitivity 26% Specificity 87%	Sensitivity 43% Specificity 80%	Teledentistry
Boye et al., 2012 ¹⁶	Dental caries	Sensitivity 65.5% Specificity 82.4%	Sensitivity 81.3% Specificity 82.4%	Face-to-face
Gomez et al., 2013 ¹⁷	Dental caries – sound (none) Dental caries – enamel Dental caries – dentine	Sensitivity >99% Specificity 87% Sensitivity 90% Specificity 87% Sensitivity 87% Specificity 93%	Sensitivity >99% Specificity 91% Sensitivity 83% Specificity 86% Sensitivity 84% Specificity 89%	Comparable
Patterson and Botchway, 1998 ¹⁸	Dental caries	NSD at 5% significance level		Comparable
Kopycka-Kedzierawski et al., 2007 ¹⁹	Dental caries	Prevalence estimate 28%	Prevalence estimate 42%	Teledentistry
Boye et al., 2013 ²⁰	Dental caries	DMFT = 1.66 DMFT = 0.97	DMFT = 1.77 DMFT = 0.97	Comparable
Morosini et al., 2014 ¹⁰	Dental caries	NR^a	Accuracy 95–96%	Comparable
Elfrink et al., 2009 ²¹	Dental carries (per tooth) PMH	NR^a NR^a	Sensitivity 85.5% Sensibility 83.6% Sensitivity 72.3% Specificity 92.8%	Comparable
Wong et al., 2005 ²²	DDE	Prevalence estimate 34%	Prevalence estimate: 5 view image set 35%; 3 view image set 35%; 1 view image set 37%	Comparable
Golkari et al., 2011 ² ³	DDE	The photographic method detected significantly more (p < 0.001) DDE than the direct examination method.		Teledentistry
Chen et al., 2013 ² ⁴	DDE	The photographic method detected significantly more (p < 0.05) DDE than the direct examination method.		Teledentistry
Tabari et al., 2000 ²⁵	Fluorosis	Prevalence (fluorosis) detected in three populations groups: 38%, 54% and 23%.	Prevalence (fluorosis) detected in three population groups: 37%, 52% and 21%.	Comparable
Martins et al., 2009 ²⁶	Fluorosis	Sensitivity and specificity NR^a Prevalence (fluorosis) estimate: 49%	sensitivity 70.8% specificity 96% Prevalence (fluorosis) estimate: 37%	Face-to-face
Cruz-Orcutt et al., 2012 ²⁷	Fluorosis	Prevalence (fluorosis) estimate: 18%	Prevalence (fluorosis) estimate: 33%	Teledentistry
Al-Malik et al., 2001 ²⁸	Tooth wear and erosion Extensive erosion	Prevalence: 36% Prevalence estimate: 14%	Prevalence estimate: 30% Prevalence estimate: 8%	Face-to-face

Considered gold standard

DDE: developmental defects of the enamel; PMH: primary molar demineralisation; NR: not reported; DMFT: decayed, missing, filled teeth (permanent); NSD: no significant difference

Quality and risk of bias

For the case selection domain, 19% of studies were judged to be at high risk of bias and 37% were considered unclear. This was because of lack of information about the range of disease’s severity, the prevalence of the disease or related to the choice of high-prevalence disease settings. Furthermore, all studies used convenience samples.

For the index test domain, 13% of studies were judged to be at high risk of bias and 50% were considered unclear. The main concern was the number of examiners – over 44% of studies had only one examiner. For the reference standard domain the risk of bias was judged to be high or unclear in 50% of the cases. This was because of the lack of calibration and validation by multiple examiners. For the time and flow domain, 25% of the studies were judged to be unclear. This was because there was no clear information about the washout time between visual inspection and image analysis.

In the index test domain, 20% of studies were considered to have low applicability to the review question. Clinical applicability was also a concern for in vitro studies. The summary of the QUADAS-2 analysis is presented in Figures 2 and 3.

Figure 2.

Summary of quality assessment of diagnostic accuracy studies (QUADAS-2) assessments for risk of bias.

Figure 3.

Summary of quality assessment of diagnostic accuracy studies (QUADAS-2) assessments for applicability.

Discussion

In regards to the nine studies which compared accuracy of assessments on dental caries, three studies found image evaluation to be superior to visual inspection and the remaining six were equivalent. Two of the three studies that found image evaluation to be superior were conducted in vitro. In vitro studies are important to assess the diagnostic accuracy of dental caries because they can use the gold-standard histological confirmation of diagnosis.²⁹ However, in vitro studies have serious limitations in clinical applicability because the difficulties imposed by the working in oral cavity in a clinical setting (small space, poor light, presence of saliva, patient movement) are minimised.

Permanent teeth were examined in seven studies and deciduous teeth in four studies. Five of the nine studies evaluated only molars and premolars (one included canines). Almost half of them restricted the screening to the occlusal surfaces. Occlusal surfaces of posterior teeth are the most vulnerable sites for dental caries. Neither inspection technique is able to detect small interproximal lesions. Therefore, analysis of the occlusal surfaces only was considered justified. With the exception of the study that evaluated PMH, all other enamel defect studies evaluated only anterior teeth. This is justified as most consultations are for aesthetic complaints.

Visual inspection is an important tool in clinical settings for oral epidemiology and oral health surveillance. Given that photographic examination has the same limitations as visual inspection, this may indicate store-and-forward teledentistry is most applicable to the same clinical settings.

Limitations

This review has a number of limitations. The included studies were heterogeneous because different indexes were used to classify disease, personnel, equipment and methodology. The heterogeneity did not permit definitive conclusions about the performance of the two techniques. Further, many of the studies were judged to have a high or unclear risk of bias, which may further reduce confidence in the findings. We only used the PubMed database to search for studies for this review. This search strategy may have excluded articles that are only indexed by other sources.

Conclusion

There is very limited published evidence which compares the diagnostic accuracy of image analysis with in person visual inspections. Taking into account the limitations reported in this review, it seems that most studies in this area have found at least comparable results between photographic techniques and conventional methods of dental assessment for common dental conditions. However, the wide variation in equipment and personnel used for the collection and interpretation of clinical images made it impossible to generalise the results. Whilst the perceived advantages of teledentistry for patients living in remote areas is understandable in terms of access, it remains unclear exactly how effective store-and-forward teledentistry is for diagnosis of common dental conditions in children and adolescents.

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: this work has been partially funded by The Brazilian National Council for Scientific and Technological Development (CNPq).

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