Detection of occlusal carious lesions: An in vitro comparison of clinicians’ diagnostic abilities at varying levels of experience
By Eric Swenson, DDS
Bernard Hennessy, DDS, FAGD, ABGD
Featured in General Dentistry, January/February 2009
Pg. 60-66
Posted on Wednesday, January 07, 2009
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There are many different methods available for detecting occlusal caries. This in vitro study, performed on 94 extracted human teeth, examines differences in diagnostic abilities (using visual and tactile methods) and examines restorative choices among 21 dental clinicians, based on amount of clinical experience. Test subjects examined the extracted teeth and utilized a mirror explorer, bitewing radiographs, and magnification to diagnose suspected occlusal caries. The teeth were sectioned and diagnosed macroscopically to obtain a sensitivity and specificity value for each clinician. Based on the results, there is no strong correlation between a dentist’s amount of experience and a more accurate diagnosis or more conservative treatment options.
Received: January 29, 2008
Accepted: April 4, 2008
The detection of occlusal caries often is a challenging process. While grossly carious occlusal lesions are easy to detect, many teeth have “hidden lesions” (that is, non-cavitated lesions where the enamel has re-mineralized). Use of fluoridated dentifrice may contribute to this phenomenon.1 Factors that should be considered when diagnosing occlusal caries and deciding when and how to treat it include patient history, clinical presentation, diet, caries risk, and radiographic evaluation. Three other factors—lesion site, lesion appearance, and lesion activity—all help to increase the validity of a diagnosis.2
Numerous studies have been published concerning correct caries diagnosis and appropriate treatment considerations.2-4 Diagnostic aids that have resulted from this research and development have included DIAGNOdent (KaVo Dental Corporation, Lake Zurich, IL; 800.323.8029), Digital Imaging Fiber-Optic Trans-Illumintaion (DIFOTI, Electro-Optical Sciences, Inc., Irvington, NY; 800.729-8849), and the electronic caries monitor (ECM).5 Despite these recent technological advances, the traditional method of using a mirror, an explorer, a clean surface, and radiographs to diagnose occlusal caries remains in wide use.6
Laser fluorescence (DIAGNOdent) has become an increasingly popular method for detecting caries. According to a 2006 article, laser fluorescence shows good sensitivity and correctly identified 7 to 9 of every 10 histologically confirmed dentinal carious lesions; however, the improved sensitivity comes at the cost of reduced specificity (and perhaps a potential for unnecessary operative intervention).7
DIAGNOdent has been shown to be most useful for detecting occlusal caries; by contrast, DIFOTI has shown some promise when used to detect interproximal caries. Schneiderman et al reported sensitivity values of 0.56 and noted that DIFOTI is three times more sensitive than bitewings in detecting occlusal caries.8
The ECM, which evaluates electrical conductance through tooth structure, has proven useful in detecting occlusal caries. Demineralized tooth structure exhibits a higher conductance of electricity than mineralized tooth structure. In studies that compared the ECM to other detection methods, Ashley et al reported a sensitivity value range from 0.65–0.78 on occlusal non-cavitated surfaces, while a 2007 study by Ekstrand et al reported sensitivity values from 0.80–0.85.9,10 At present, there is no ECM unit available for private practice use.
According to the literature, probing fissures with a sharp explorer is ineffective for detecting caries, demonstrating a sensitivity value of only 0.24.11 This method of detection has been viewed negatively for many reasons. Probing with an explorer may transmit cariogenic flora from an infected tooth to a previously uninfected tooth, or it may cause cavitation in a lesion that could be remineralized. The literature indicates that explorer probing is no more accurate than visual examination alone.12,13 Most studies that examine probing with an explorer find that this method has a low sensitivity value (24%) and a high specificity (99%).11
The initial occlusal carious lesion forms on the fissure wall and cannot be seen easily.5 Fluoride-remineralized occlusal surfaces are prone to cavitations that take time to manifest because the remineralized surfaces hide the carious lesion in the dentin.1 A 1992 study by Nytun et al evaluated the diagnosis of occlusal caries based on visual inspection only and found that only 30% of occlusal lesions in their sample were identified correctly.14 That same year, Wenzel et al studied deeper occlusal lesions and reported that 50% of the teeth examined had intact occlusal surfaces, with no indication that the caries process had reached well into dentin.15
Although explorers still are used widely for detecting occlusal caries, the literature suggests that they may not be the best tool for this purpose.11,16,17 According to
This study evaluated differences in occlusal caries diagnostic efficiency based on amount of clinical dental experience. Secondarily, this study sought to evaluate differences in proposed treatment modalities based on amount of clinical experience. This in vitro study was conducted using extracted human teeth. For the purposes of this study, the following null hypothesis was proposed: There are no differences in diagnostic ability and treatment decisions based on the number of years of clinical experience.
Materials and methods
Selection, cleaning, and mounting of experimental teeth
For this study, 94 extracted human teeth were obtained from the oral surgery department of an ambulatory dental clinic. For all teeth, the occlusal surface was intact, no visible cavitation was present, occlusal fissures were stained or discolored, no previous restorations were present, and all teeth had erupted into the oral cavity. Most of the teeth selected were third molars that had been scheduled for extraction; however, other teeth were included in the study if they met the established criteria. The only exceptions were the control teeth. Two of the teeth had never erupted into the oral environment and were guaranteed to be caries-free. The other control tooth had an obvious cavitated lesion.
The teeth were cleaned (using a rubber cup and flour of pumice) and stored in 5% neutral buffered formalin. Each tooth was mounted in laboratory stone (Hydrock Type III, Kerr Dental,
Photographs and radiographs
The occlusal surface of each subject tooth was photographed using a digital camera (Canon 20D,
Tooth examination
Twenty-one dentists, with clinical experience ranging from 1–42 years, received a copy of each photographed tooth, a bitewing radiograph of each tooth, an explorer, and a red pen to mark suspected lesions. Examiners were instructed to use the explorer, radiograph, and magnification, if they so desired, to detect carious lesions. Examiners were asked to mark the location on the photograph of the tooth indicating wherever they believed occlusal caries to be present; in addition, examiners were asked to relate how they would restore the tooth. If no lesion was suspected, the examiner would not mark the photograph. Participants also were asked to list the number of years they had been practicing clinical dentistry.
Sectioning of teeth
After examination, teeth were marked with an indelible marker for sectioning for the greatest likelihood of exposing carious areas of each tooth. The lead author (ES) reviewed all photographs and decided where teeth should be sectioned, based on a review of all examiners’ findings. The teeth were sent to the U.S. Army Dental Materials Laboratory at
Examination of sectioned teeth
The lead author examined all sectioned teeth under loupe magnification to detect the presence of caries upon macroscopic examination. Teeth were considered carious if the caries process had cavitated and/or proceeded to or past the dentoenamel junction (DEJ) of the examined tooth. Darkly stained pits and fissures and white spot lesions confined to enamel were not considered carious. Each tooth was designated as positive or negative for occlusal caries based on macroscopic examination of the individual slices. A caries-indicating solution (Caries Indicator, Henry Schein, Melville, NY; 800.472.4346) did not prove to be effective in indicating areas of denatured collagen in this study, as only rough areas would pick up the stain; areas of obvious decay showed either very light staining or no staining at all. This lack of staining was attributed to the dehydrated nature of the teeth.
Select sectioned teeth were photographed to illustrate the decision-making process (Fig. 1); at this point, the data were correlated to the responses of each examiner. Determination of false positives, false negatives, true negatives, and true positives were compiled in a database.
Statistical analysis
Sensitivity and specificity were determined for each study participant. Sensitivity is defined as the proportion of individuals in a population who will be identified correctly when a test designed to detect a particular disease is administered. Specificity is defined as the statistical probability that an individual who does not have the particular disease for which the test is conducted will be identified correctly as negative.
Data also were compiled concerning examiners’ responses as to how each one perceived how the carious tooth would be restored. Each restoration was grouped into one of five categories based on restoration complexity: sealant, a preventive resin restoration (PRR) restoration that could be limited to a single pit or fissure, a composite resin, an amalgam, or a full-coverage restoration (FCR) that would include both onlays and crowns. Restorations were considered only for teeth that were identified as true positives after sectioning. The restoration choice of each examiner was recorded and placed in one of the above categories; at that point, groups of restorations were plotted in a graph to observe trends in terms of choosing a certain type of restoration based on the examiner’s years of experience.
Results
Sensitivity values ranged from 0.882 to 0.231, with a median of 0.561 and a mean of 0.572. Specificity values ranged from 0.938 to 0.455, with a median of 0.699 and a mean of 0.698. The Pearson product-moment correlation can be calculated to determine the relationship between sensitivity, specificity, and years of clinical experience. In this study, Sensitivity:years of experience had a value of r = –0.55, while Specificity:years of experience had a value of r = 0.12 (Chart 1). The Pearson product-moment correlation also was calculated to examine the correlation between sensitivity and specificity without considering years of experience; this correlation produced a value of r = 0.48. The trend was statistically significant (p = 0.029).
Restorations were recorded only for the teeth that were deemed to be carious after sectioning. Three of the 21 examiners did not indicate which restoration they would choose and were excluded from this portion of the study. The remaining 18 examiners suggested a total of 392 restorations: 11 sealants, 103 PRRs, 87 composites, 178 amalgams, and 13 FCRs (Chart 2). Correlation between years of experience and degree of treatment was calculated using the Spearman rank order test, providing a correlation value of –0.43.
Discussion
Despite many efforts to classify dentistry as a strictly scientific field, dentists still find themselves using their best clinical judgment to make subjective diagnoses, especially when occlusal caries is involved. Dentists vary greatly in their skill, education, and ability to pay attention to detail. In addition, dentists vary in terms of intra-examiner repeatability when diagnosing dental disease, including residual caries and endodontic radiographic interpretation.19,20
Multiple studies have evaluated dentists’ ability to assess the presence of caries based on levels of education and experience.21-24 A 1995 article by Lazarchik et al found no great difference in sensitivity among first-year dental students, fourth-year dental students, and dental faculty in terms of their ability to detect occlusal caries using radiographs.25 However, there was a trend toward greater specificity as the experience of the practitioner increased.
The authors hypothesized that more experienced dentists would be more aware of the complications of overtreatment. Conversely, dental students focused more on diagnosing all disease—misdiagnosing a carious lesion is unacceptable in the dental school setting and may have serious negative repercussions in terms of grading. Educational level, education methods, and caries location were determined to be factors that related to a practitioner’s ability to diagnose occlusal caries accurately.25 All studies suggested that a more uniform method of teaching caries diagnosis and subsequent treatment decisions needs to be implemented in more dental school curricula.21-23, 25
The sensitivity and specificity values found in the present study were similar to those published previously.21-24 In the present study, sensitivity did not improve when the amount of experience increased. Caution should be used when interpreting this result, as there was only a weak correlation value (r = –0.55) and the examiner experience pool was weighted more heavily toward the range of 1–10 years. In terms of specificity, the correlation value (r = 0.12) also was not significant; however, there was a linear relationship in terms of the amount of clinical experience.
Some of the examiners had dramatically different sensitivity and specificity values; for example, examiners 1 and 2 had the highest specificity values but the lowest sensitivity values. This finding suggests that these two examiners correctly diagnosed some carious occlusal surfaces but also failed to correctly diagnose many actual carious teeth in the study; as a result, a lot of disease went undiagnosed. This trend had a correlation value of r = 0.48. Even though this relationship is not strong, there is a definite trend and it is statistically significant (p = 0.029). This finding suggests that certain examiners would be prone to overdiagnosing—and thus prone to operate on noncarious tooth structure—or underdiagnosing and missing decay. In either case, this relationship would not be related to a clinician’s amount of experience.
This study also was designed to investigate whether a clinician’s method of restoration was less invasive as his or her amount of experience increased. The results demonstrate a weak correlation (–0.43) that suggests treatment complexity decreases as amount of clinical experience increases. As clinicians observe the potentially damaging effects of unnecessary or overaggressive surgical intervention, they consciously attempt to keep preparations smaller and avoid unnecessary loss of tooth structure. In effect, they begin to incorporate some of the tenets of a minimally invasive treatment philosophy into their practices.
The authors are unaware of any study that has examined the restorative trends of dentists based on amount of clinical experience. Results of this in vitro study do not necessarily correlate to a clinical setting where more patient-related factors would be considered; however, this model could act as a pilot study for further studies.
After deciding to restore a tooth, dentists must consider many factors, including the extent of disease, the amount and quality of remaining tooth structure, esthetic considerations, the dentist’s abilities, the patient’s finances, previous caries activity, and the patient’s desires. Caries activity cannot be overlooked in any discussion concerning caries diagnosis. Treatment decisions would benefit from the dentist knowing whether a carious lesion was truly active. The only true way to discern lesion activity is through histological examination.26 Lesions can be described as arrested, active, infected, or affected; unfortunately, the true state of caries lesion activity often is not known, which further complicates the treatment decision. Early diagnosis is critical and preferable because of the chronic and often unlimited nature of the caries disease process.
Early diagnosis allows dentists to identify carious lesions early and before they cavitate, making it possible to employ a nonsurgical intervention (such as a remineralization protocol). This approach fits well with the practice of minimally invasive dentistry. Nonsurgical treatment modalities (such as sealants, fluoridated toothpaste, and fluoride varnish) should be employed unless cavitation, loss of tooth structure, or soft, infected dentin is present. When surgical treatment is needed, dentists should try to keep the preparation as conservative as possible to allow for conservation of tooth structure. The carious process can be halted through conservative methods that include caries removal or sealing the occlusal fissure system—which, if performed properly, prevents cariogenic bacteria from accessing sugars for metabolism.27
Resistance to conservative treatment methods abounds. A 2001 study by Clark and Mjor reported that only 60% of responding dental schools in North America have adopted an antibacterial/nonsurgical approach for treating caries, while only 67% of dental schools have implemented caries risk assessment in their treatment planning protocol.28 Contemporary restorative materials and instruments facilitate these procedures so that patients can benefit from the least invasive dentistry possible.
Conclusion
Within the limits of this study, the null hypothesis holds true in that there is not a strong correlation between amount of experience and improved diagnosis of caries or more conservative restorative trends; however, this study suggests that individual dentists may be more prone to over- or underdiagnosis as an individual trend. This trend may be related to the quality of training received in dental school. The results of the present study reaffirmed that traditional occlusal caries diagnostic methods (mirror and explorer) are not highly effective for diagnosing caries accurately. The ability to diagnose occlusal caries correctly does not appear to improve with increased clinical experience when a mirror and explorer are the primary diagnostic tools.
Results from this in vitro study do not necessarily relate to actual clinical caries diagnosis. The authors made no attempt to calibrate the diagnostic process and the examiners were asked to look at the subject teeth only once. The study may have been more meaningful if the examiners were asked to re-examine the teeth at a later date to observe intra-examiner reliability. Also, observing restorative trends of practitioners in clinical settings correlated to amount of experience would give a more accurate portrayal of a clinician’s restorative choices. However, this would hold true only if done in a military or government setting, where fees would not be a biasing factor. Clearly, in a private practice setting, a patient’s ability to pay for a service as well as financial compensation for the dentist could bias results.
Acknowledgements
The authors would like to thank Dr. Steven Hondrum and the U.S. Army Dental Materials Laboratory for their valuable help in sectioning the extracted teeth and in providing statistical analysis.
Disclaimer
The opinions and findings expressed in this paper in no way represent the viewpoints of the U.S. Army or the government of the
Author information
CPT Swenson is currently at
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General Dentistry, January/February 2009 , Volume 57 , Issue 1
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