|Year : 2013 | Volume
| Issue : 1 | Page : 17-20
Caries detection in primary teeth is less challenging than in permanent teeth
Fausto M Mendes, Mariana M Braga
Department of Pediatric Dentistry, School of Dentistry, University of Sao Paulo, Av. Lineu Prestes, 2227, Sao Paulo, Brazil
|Date of Web Publication||6-Apr-2013|
Fausto M Mendes
School of Dentistry, University of Sao Paulo, Av. Lineu Prestes, 2227, Sao Paulo 05508-000
Source of Support: The study was supported by the Conselho Nacional de
Desenvolvimento Científico e Tecnológico (CNPq– Process # 476372/2006-2,
302368/2008-6 and 565061/2008-9), Pró-Reitoria de Pesquisa e de Pós-
Graduação da USP and Fundação de Amparo a Pesquisa do Estado de São
Paulo (FAPESP),, Conflict of Interest: None
Introduction: Most studies about caries detection methods have been performed using permanent teeth. Primary teeth, however, present significant differences from permanent teeth; hence findings of these studies with permanent teeth cannot be extrapolated. The Hypothesis: Our hypothesis is that the caries diagnosis process in primary teeth is less challenging than in permanent teeth. This assertion is based on the fact that primary enamel is thinner and the caries process progresses faster in this type of teeth when compared to permanent teeth. For these reasons, the majority of caries lesions in primary teeth would be more evident and therefore, easily detected through visual inspection. Only a few number of caries lesions would be missed by visual inspection. Thus, adjunct diagnostic methods, such as radiographs, would be unnecessary for primary teeth. Evaluation of the Hypothesis: To evaluate this hypothesis, researchers should conduct studies about the performance of the caries detection methods avoiding selection bias and defining appropriate settings. Clinical trials randomizing the diagnostic strategies would be worthwhile. The evidence supporting the benefits of adjunct methods in detecting caries lesions in primary lesions is limited. However, clinical guidelines have recommended the use of the radiographic method to detect caries in primary teeth in all symptomless children. The confirmation of our hypothesis would lead to the need to re-evaluate such guidelines.
Keywords: Dental caries, diagnosis, primary teeth
|How to cite this article:|
Mendes FM, Braga MM. Caries detection in primary teeth is less challenging than in permanent teeth. Dent Hypotheses 2013;4:17-20
| Introduction|| |
Caries diagnosis process has been more difficult in the last years due to the decline of caries progress observed in most countries. ,, With this decrease, demineralization develops more slowly, and therefore, caries lesions do not cavitate until later stages of the disease progression.  Clinically, intact enamel hampers the visualization of occlusal and approximal caries lesions, complicating their detection.
Traditionally, caries detection has been performed with clinical and radiographic examination. Visual inspection has performed well in terms of specificity, but the method has presented low reliability and sensitivity values.  Radiographs have been indicated to increase the sensitivity of the caries detection process. , However, most studies have been performed in permanent teeth and there is a lack of studies about caries detection methods using primary teeth.  Significant structural differences between primary and permanent teeth ,,,,, make it inaccurate to extrapolate the results obtained for one type of substrate to the other. Our belief that the caries detection process is easier and more accurate in primary than in permanent teeth is based on several principles.
| The Hypothesis|| |
There are considerable differences between permanent and primary teeth which may directly affect the caries process. Firstly, the enamel of primary teeth is thinner than that of the permanent teeth.  Secondly, the primary enamel is more porous,  less mineralized, , and has more carbonate, , less phosphorus,  and calcium phosphates  in its composition. Furthermore, caries lesions progress faster in primary than in permanent teeth. 
Considering all these factors, it is plausible to state that the overlying enamel in dentine caries lesion breaks more easily in primary than in permanent teeth. Therefore, less non-evident caries lesions would occur in primary teeth than in permanent ones. On the other hand, in permanent teeth, since the enamel is approximately twice as thick, it is harder to break and caries lesions remain undetected for longer periods. Some authors named this condition as "hidden caries." ,, Hidden caries have been defined as extensively demineralized occlusal dentin caries lesions not detected through visual inspection, which can be detected by radiographs. ,, Less "hidden caries" would be present in primary teeth probably because the faster progression of caries lesions and thinner enamel. The primary enamel would easily break, making the lesion evident.
The definition of hidden caries can be also applied to approximal lesions where dental caries progresses under the marginal ridge making it difficult for dentists to visually detect them. Even though the marginal ridge is more difficult to break than other regions of the enamel, this fracture also occurs more easily in primary than in permanent teeth.
Therefore, we hypothesized that the caries detection both in approximal and occlusal surfaces of primary molars would be easier than the process in permanent molars due to a greater number of evident caries lesions that can be expected to occur in primary teeth. The evident caries lesion is easily detected during the clinical examination  and adjunct methods are not necessary in such cases. 
The evidence supporting this hypothesis in the literature is still lacking. Few studies have found a better performance of the visual examination method in primary than in permanent teeth. In a systematic review published in 2002, the authors affirmed that there was a lack of studies about the performance of traditional caries detection methods in primary teeth.  In another systematic review assessing the performance of a laser fluorescence device to detect caries lesions, named DIAGNOdent, studies using primary teeth showed a slightly higher specificity than studies in permanent teeth. 
Furthermore, few studies have compared the performance of different methods for detecting caries lesions in primary and permanent teeth. Studies using different methods to detect occlusal caries lesions, such as visual inspection, laser fluorescence and radiographic methods have found only a slightly better performance in primary compared to permanent teeth. ,,
This superiority of caries detection performance in primary teeth is not clear yet. A possible explanation is that the authors usually choose a convenience sample to perform studies about methods of caries detection. For example, the authors select teeth with suspected caries lesions and they usually exclude teeth with evident cavitations. On one hand, this procedure is comprehensible since the inclusion of cavitation's in the sample would increase the performance of the methods.  Changes in the spectrum of the disease usually increase the performance of diagnostic methods , and probably overestimate their performance in a population presenting low caries progression. On the other hand, the exclusion of more advanced caries lesions causes a decrease in the external validity of the studies because the spectrum of the disease does not reflect the actual occurrence of caries in some populations.
Our hypothesis is based on the faster progression of caries and thinner enamel of primary teeth. In the daily clinical practice, primary teeth present a higher prevalence of evident caries lesions than permanent teeth. Therefore, visual inspection would be more accurate in this type of tooth. Adjunct methods of caries detection are indicated to detect non-evident caries lesions, mainly at occlusal (hidden caries) and approximal surfaces.  Therefore, such methods would be more useful in permanent teeth, where a higher prevalence of non-evident caries lesions is expected.
This statement is contrary to current recommendations of the most renowned clinical guidelines in Pediatric Dentistry. Both European and American clinical guidelines concerning dental radiographs in children recommend that the dentists take two radiographs in all symptomless children with primary teeth in order to detect caries lesions missed by visual inspection. , However, the low prevalence of non-evident caries lesions in primary teeth contradicts this recommendation. In fact, we observed a low prevalence of cavitated caries lesions in approximal surfaces of primary teeth (around 5%) and adjunct radiographic or laser fluorescence methods did not have a better performance than that of visual inspection, increasing the number of false positive results. , False positive results are undesirable since they lead to unnecessary operative treatment. Moreover, despite the low-level X-rays used in dental radiographs, any dose of radiation would have the potential to cause biological harm according to the current theory in radiation protection, especially in young children whose cells are highly undifferentiated. 
Therefore, such clinical guidelines should be reviewed, changing the current thinking about caries diagnosis process in primary teeth. For this purpose, new studies need to be performed to prove our hypothesis.
| Evaluation of the Hypothesis|| |
To test our hypothesis, researchers should perform clinical studies in both permanent and primary teeth selecting a consecutive or randomized sample of subjects avoiding convenience samples. Furthermore, researchers have to define an appropriate setting for the study. Concerning the caries detection methods, the best setting is the dental office and the study should include subjects who looked for dental treatment at a clinic or dental school.
Another important point is that the performance of the visual inspection method, which is of essential use in all patients,  should be evaluated in all teeth and frank cavitations should not be excluded from sample. Obviously, the method will perform better using these selection procedures. However, if the authors select patients with primary and/or permanent teeth, it will be possible to prove that caries detection in primary teeth is more accurate than in permanent ones. Other methods, such as radiographic and laser fluorescence, should be used only as adjunct to visual inspection in cases when the dentist has doubts about the correct diagnosis. These adjunct methods are more useful in permanent teeth. Furthermore, randomized clinical trials conducted in children to evaluate the two different caries diagnosis approaches: visual inspection alone and visual inspection and radiographic method.
Thus, considering all aspects discussed in the present text, visual inspection probably performs better in detecting caries lesions in primary teeth and the use of adjunct methods may not lead to many benefits. The recommendations of the clinical guidelines that dentists should take two bitewing radiographs in symptomless children with primary teeth in order to detect caries lesions should, therefore, be re-evaluated. New studies should be performed in a sample of consecutive subjects who sought dental treatment, avoiding the selection of a convenience sample. The actual prevalence of non-evident caries lesions in primary teeth is low and therefore, visual inspection probably suffices to obtain a good performance in the caries diagnosis process in children with primary teeth.
| Acknowledgment|| |
The authors wish to thank Dr. Christiana Murakami for English corrections and the valuable critical considerations about the text.
| References|| |
|1.||Bader JD, Shugars DA, Bonito AJ. A systematic review of the performance of methods for identifying carious lesions. J Public Health Dent 2002;62:201-13. |
|2.||Wenzel A. Current trends in radiographic caries imaging. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;80:527-39. |
|3.||Weerheijm KL. Occlusal 'hidden caries'. Dent Update 1997;24:182-4. |
|4.||Amaechi BT, Higham SM, Edgar WM. Factors influencing the development of dental erosion in vitro: Enamel type, temperature and exposure time. J Oral Rehabil 1999;26:624-30. |
|5.||Hunter ML, West NX, Hughes JA, Newcombe RG, Addy M. Relative susceptibility of deciduous and permanent dental hard tissues to erosion by a low pH fruit drink in vitro. J Dent 2000;28:265-70. |
|6.||Hunter ML, West NX, Hughes JA, Newcombe RG, Addy M. Erosion of deciduous and permanent dental hard tissue in the oral environment. J Dent 2000;28:257-63. |
|7.||Lippert F, Parker DM, Jandt KD. Susceptibility of deciduous and permanent enamel to dietary acid-induced erosion studied with atomic force microscopy nanoindentation. Eur J Oral Sci 2004;112:61-6. |
|8.||Mortimer KV. The relationship of deciduous enamel structure to dental disease. Caries Res 1970;4:206-23. |
|9.||Shellis RP. Relationship between human enamel structure and the formation of caries-like lesions in vitro. Arch Oral Biol 1984;29:975-81. |
|10.||Correr GM, Alonso RC, Consani S, Puppin-Rontani RM, Ferracane JL. In vitro wear of primary and permanent enamel. Simultaneous erosion and abrasion. Am J Dent 2007;20:394-9. |
|11.||Boston DW. Incipient and hidden caries. Dent Clin North Am 2005;49:11-2. |
|12.||Ricketts D, Kidd E, Weerheijm K, de Soet H. Hidden caries: What is it? Does it exist? Does it matter? Int Dent J 1997;47:259-65. |
|13.||Lussi A. Impact of including or excluding cavitated lesions when evaluating methods for the diagnosis of occlusal caries. Caries Res 1996;30:389-93. |
|14.||Braga MM, Mendes FM, Ekstrand KR. Detection activity assessment and diagnosis of dental caries lesions. Dent Clin North Am 2010;54:479-93. |
|15.||Bader JD, Shugars DA. A systematic review of the performance of a laser fluorescence device for detecting caries. J Am Dent Assoc 2004;135:1413-26. |
|16.||Ketley CE, Holt RD. Visual and radiographic diagnosis of occlusal caries in first permanent molars and in second primary molars. Br Dent J 1993;174:364-70. |
|17.||Braga MM, Mendes FM, Imparato JC, Rodrigues CR. Effect of cut-off points on performance of laser fluorescence for detecting occlusal caries. J Clin Pediatr Dent 2007;32:33-6. |
|18.||Rodrigues JA, Diniz MB, Josgrilberg EB, Cordeiro RC. In vitro comparison of laser fluorescence performance with visual examination for detection of occlusal caries in permanent and primary molars. Lasers Med Sci 2009;24:501-6. |
|19.||Guyatt GH, Sackett DL, Haynes RB. Evaluating diagnostic tests. In: Haynes RB, Sackett DL, Guyatt GH, Tugwell P, editors. Clinical Epidemiology: how to Do Clinical Practice Research. Philadelphia: Lippincott Williams and Wilkins; 2006. p. 273-322. |
|20.||Lijmer JG, Mol BW, Heisterkamp S, Bonsel GJ, Prins MH, van der Meulen JH, et al. Empirical evidence of design-related bias in studies of diagnostic tests. JAMA 1999;282:1061-6. |
|21.||American Academy on Pediatric Dentistry Ad Hoc Committee on Pedodontic Radiology, American Academy on Pediatric Dentistry Council on Clinical Affairs. Guideline on prescribing dental radiographs for infants, children, adolescents, and persons with special health care needs. Pediatr Dent 2008;30:236-7. |
|22.||Espelid I, Mejàre I, Weerheijm K, EAPD. EAPD guidelines for use of radiographs in children. Eur J Paediatr Dent 2003;4:40-8. |
|23.||Novaes TF, Matos R, Braga MM, Imparato JC, Raggio DP, Mendes FM. Performance of a pen-type laser fluorescence device and conventional methods in detecting approximal caries lesions in primary teeth- in vivo study. Caries Res 2009;43:36-42. |
|24.||Novaes TF, Matos R, Raggio DP, Imparato JC, Braga MM, Mendes FM. Influence of the discomfort reported by children on the performance of approximal caries detection methods. Caries Res 2010;44:465-71. |