Use of laser fluorescence ( DIAGNOdent ® ) for in vivo diagnosis of occlusal caries : a systematic review

This systematic review was conducted to assess the accuracy of laser fluorescence (DIAGNOdent®) for diagnosis of occlusal caries in permanent teeth, using any sort of gold standard. The MEDLINE, LILACS, BBO and Cochrane library databases accessed by BIREME were searched for English, Spanish and Portugueselanguage papers published between 1982 and 2003. Four works in English were selected. DIAGNOdent® was found to be an accurate method for diagnosis of occlusal caries, mainly if employed simultaneously with visual inspection. First published in J Appl Oral Sci 2004; 12: 17781.


Introduction
Despite its decreasing prevalence in the Brazilian population, dental caries is still an important public health problem 1,2 .The diagnosis of dental caries remains a challenge, since its patterns and prevalence have greatly changed in the last few years.The difficulty in diagnosing dental caries lies not only on the morphological changes of lesions and their rate of progression, but also in the lack of a precise methodology for correctly diagnosing both the disease (accuracy) and the integrity of dental structure (specificity) [3][4][5][6] .
The areas most affected by dental caries are the occlusal surfaces, of which 50 to 60% are damaged by the disease 7 .Consequently, early diagnosis of lesions and the establishment of non-invasive treatments consequently have been highly encouraged, to preserve the surface integrity.In fact, when compared to the others, occlusal surfaces are known to be the surfaces most susceptible to caries.In addition, they are also the most frequently restored and the most difficult to diagnose 8- 11 .
The methods traditionally employed for diagnosis of caries include clinical (visual) inspection, tactile examination by probing and bitewing radiographs 1,12 .Clinical examination has been proven as suitable for smooth surfaces, but inadequate for proximal and occlusal surfaces.Radiographic images, on the other hand, are useful for detecting enamel proximal enamel lesions and occlusal dentin lesions, but are usually unsuitable for identifying occlusal caries restricted to enamel.Other methods such as fibre optic transillumination (FOTI) and videoscopic examination have been under discussion and some have already been developed to help in the diagnosis of caries.
The accuracy of FOTI is very similar to that of visual examination 6,13,14 , whereas the videoscopic examination has a lower specificity 15,16 .Laser fluorescence has been also used to aid in diagnosing occlusal caries.
This review compiled all works on the DIAGNOdent® appliance, the laser fluorescence of which has been employed on in vivo occlusal surfaces of permanent teeth.The aim was to evaluate the diagnostic accuracy of such a device for occlusal caries.

Material and methods
Research sources: Databases searched were MEDLINE, LILACS (Latin American and Caribbean Literature on the Health Science), BBO (Brazilian Bibliography of Dentistry) and Cochrane Library accessed by BIREME website (Latin American and Caribbean Center on Health Sciences Informationwww.bireme.br).

Types of participants:
All studies on human beings were selected, regardless of age.
Types of study: All diagnostic clinical trials, on human beings and occlusal surfaces were included.The following languages were chosen: English, Portuguese and Spanish.

Type of outcome:
The outcome of interest was the presence or absence of dental caries as confirmed by the following methods: histological examination, opening of cavities or clinical examination based on scores utilized in studies based on histological corroboration.

Exclusion criteria
In situ and in vitro studies performed on smooth surfaces and primary teeth.All types of studies available on these two databases were searched for (theses, dissertations, monographs and papers).
Cochrane Library: The text word diagnodent was used to search the Cochrane Library.

Review methods
All reports identified by the search were printed out and independently analyzed by two reviewers on the basis of title, keywords and abstract (when available), to check whether the study was likely to be relevant.The full report of all relevant papers was obtained and also when a paper could not be classified.When there was disagreement a third reviewer was consulted to achieve consensus.
The reviewers were not blinded as to authors, journals, date of publication, financial support or results.The inclusion criteria were applied and the data assessed and independently extracted by two reviewers.Consensus was sought in case of discrepancy.This was conducted according to the Users' Guides in the JAMA series on the Rational Clinical Examination 15,17 .

Results
The searches strategies yielded 11 reports from the MEDLINE database.All had been published in the English language between 2001 and 2003.Four of these met the selection criteria after reading the full articles were read.Of the seven reports excluded, 3 were literature reviews and the remaining 4 were in vitro investigations.
One of all the selected studies (Anttonen et al. 18 ) examined in deciduous and permanent teeth.Nevertheless, only data Journal Of Minimum Intervention In Dentistry related to permanent teeth were appraised in this review.Two reports, published in 2000 and 2001, and in Portuguese language, were found in the LILACS database.These were excluded because the studies were performed on the deciduous dentition.
Three references were found in the BBO database, all in Portuguese language.Two of these were also in the LILACS database; the third was an in vitro study.
Four reports in English language were found in the Cochrane Library.All had already been found in the previous databases.
Therefore, four studies were selected for analysis of the methodology and data reliability (Table 1).

Discussion
The occlusal surface is the area most susceptible to dental caries.It is also the most difficult surface for reliable detection of caries.For this reason, several investigators have attempted to discover a method capable of assisting the clinical examination in diagnosing occlusal caries.Such a method would be highly useful for incipient lesions that otherwise could not be detected by visual examination alone.In fact, this would definitely allow earlier and more conservative treatments, thus ensuring maximum preservation of dental structure.
Among the methods reviewed, laser fluorescence of the DIAGNOdent® appliance (KAVO, Biberach, Germany) has shown to be promising.However, most published articles have been about in vitro investigations, the data of which are not easily applied to the clinical setting.For this reason, only clinical studies that tested the accuracy of the DIAGNOdent® laser for diagnosis of occlusal caries were considered in the present literature review.These studies were also expected to use a diagnostic gold standard for comparison.In the present literature review, Lussi et al. 9 (2001), Heinrich-Weltzien et al. 19 (2002) and Anttonen et al. 18 (2003) regarded cavity opening as a gold standard, whereas Sheehy et al. 11 relied on clinical examination.The clinical characteristics achieved were compared to the histological criteria of an in vitro study performed by Lussi et al. 20 in 1999, as well as to DIAGNOdent® (Kavo) manufacturer's criteria.Cavity opening or tooth extraction (for histological analysis) can be considered gold standards for the evaluation of diagnostic methods.However, the opening of cavities should always be avoided in borderline cases, clinical examination is satisfactory, although quite limited 5 .As tooth extraction would only be considered on permanent teeth extracted for orthodontic or prosthetic reasons, the reliability of any investigation is limited.
Another aspect to consider is whether the test results and gold standard were assessed independently of each other.The interpretation of a new test is likely to be influenced by the knowledge of the results of the reference standard (or vice versa).Therefore the independent interpretation of both is highly important.Assessment was accomplished with measurement of the DIAGNOdent® completed independently.As a result, the examinations were not influenced by laser fluorescence values.
Comparison between the results of DIAGNOdent® and a gold standard is represented by values of methodological sensitivity and specificity.In the study reported by Lussi et al. 9 , in which carious dentin was the cut-off point, the sensitivity and specificity of the experimental method (DIAGNOdent®) were 92% and 86%, respectively.When carious enamel was the threshold, sensitivity was about 96%.Similar outcomes were found for the dentinal caries.Anttonen et al. 18 observed a sensitivity of 92% and specificity of 82% with employment of a cut-off point of 30.Similarly, the study conducted by Heinrich-Weltzien et al. 19 revealed sensitivity values of 93% but the specificity was lower (63%) when compared to the others.The study of Heinrich-Weltzien et al. 19 , on the other hand, observed a specificity 20% lower than the other investigations.This was probably due to the exclusion of caries-free molars, which were assessed but not operatively validated.On the other hand, this procedure avoided the problem of false negative findings, which are common in clinical studies with respect to ethical aspects.With regard to the subjects selected; the inclusion of a spectrum of patients very similar to those of clinical practice was observed in all studies.In fact, the samples contained all occlusal surfaces of any tooth (molar or premolar) from the maxillary or mandibular arches.

Journal
Another essential feature to be discussed is the test reproducibility and interpretation, which are directly important for clinical practice.Comparison of the final results to those of other studies requires them to be reproducible.Reproducibility reflects nothing other than the precision of diagnostic instruments.In other words, it represents the agreement of results when an examination is repeated under identical or very similar conditions.Reproducibility is a fundamental characteristic when the goal is to assess the accuracy of a diagnostic method.The kappa coefficient has been employed to measure the agreement of categorical data and seems to be very important for assessment of the reproducibility of a method 21 .When noncategorical quantitative data are being considered, correlation coefficients seem to be a much better choice 21 .Lussi et al. 9 and Sheehy et al. 11 calculated the kappa value for DIAGNOdent® of 0.98 and 0.89, respectively.Lussi et al. 9 achieved a value of 0.93 in the study for categorical data.Similarly, Anttonen et al. 18 achieved a kappa value of 0.85, whereas Heinrich-Weltzien et al. 19 found a kappa value of 0.75.These figures represent good to excellent agreement.However, being reproducible is not always as important, because a test may be reproducible, but inaccurate.
It should also be mentioned that the test description should be clear enough to permit replication of the study.The DIAGNOdent® method was clearly described in all studies selected.
The results of the studies evaluated allow us to conclude that DIAGNOdent® is a reproducible and accurate diagnostic tool that may be considerably helpful for clinical diagnosis.
Considering the present literature review, the results of which were shown to be acceptable, DIAGNOdent® may be regarded as an auxiliary diagnostic method to aid in disclosure of dental caries in surfaces where they tend to be extremely hidden from the eyes.In turn, this may considerably decrease the risk of false-positive or falsenegative diagnosis that could otherwise lead to equivocal and harmful treatments.With the improvement in diagnostic precision, less dental structures will be damaged and the patients will be granted with further clinical profits.

Conclusion
The literature review demonstrated that laser fluorescence (DIAGNOdent®) is an accurate method for diagnosis of occlusal caries, particularly when associated with visual inspection.Further investigation should however be conducted in populations with caries whose patterns differ from those observed in the evaluated studies.This would certainly broaden the spectrum of teeth with a clinically doubtful diagnosis.

Journal
following strategy was employed for MEDLINE: (Diagnodent OR laser fluorescence OR laser fluoroscopy) AND (occlusal OR occlusal) AND not vitro [Words] AND English OR Portuguese OR Spanish [Language], from 1982 to 2003.LILACS and BBO: LILACS and BBO were searched from 1982 to 2003, using the terms: (Diagnodent OR laser fluorescence OR laser fluoroscopy) AND oclusa$ AND not vitro [Words] AND English OR Portuguese OR Spanish [Language].

Table 1 :
Selected studies about DIAGNOdent® employed on in vivo occlusal surfaces of permanent teeth of an in vitro study reported by Lussi et al.20.In this case, specificity was 33%, whereas sensitivity was 100%.Such divergence in the results were probably due to the in vitro design of the Lussi et al.20study, compared to the in vivo survey done by the manufacturer.A noticeable finding is that the manufacturer's results were very similar to those revealed by Lussi et al. 9 in 2001, who also elected to conduct an in vivo investigation (86% and 92%, respectively).However, sensitivity in the Sheehy et al. 11 study was lower.