Drs. Sean C. Adler, Elliott M. Moskowitz, and Mark S. Hochberg uncover some facts on this stealthy form of caries



Abstract

Hidden caries is considered a form of caries that has as one of its distinguishing features an inability to be solely detected from a visual clinical examination and only diagnosed from radiographic images. As such, hidden caries remains an insidious form of caries that is of concern to the pediatric dentist and orthodontist. Early diagnosis of hidden or developmental caries is an important clinical goal because failure to recognize this form of caries can lead to progressive pulpal involvement and limit clinical options. The orthodontist might be the first clinician to detect this form of caries, and therefore, he/she needs to be vigilant when viewing panoramic radiographs in order to identify hidden caries. Communication between the orthodontist and pediatric dentist, as well as the routine sharing of radiographic images, remain important elements of modern comprehensive oral health care during orthodontic treatment.

Introduction

The dental profession has made notable advances in the prevention of caries. Systemic fluoride, the use of sealants, regular dental examinations, appropriate patient home care, and sound patient dietary habits have all contributed to a significant reduction in dental caries. Despite these advances, caries has not been completely eliminated and still presents the potential to damage enamel, dentin, and pulpal tissues. A description of an insidious form of caries sometimes referred to as “hidden caries” has been described by Skillen in 1941.1 The term “hidden” has been used because this form of caries is not readily detected by visual/clinical examination and is only detected radiographically. An example of such caries can be seen in Figure 1 in which a radiolucent area is clearly visible within the mandibular right second premolar; however, clinical examination failed to detect any “break” in the enamel structure. Other terms that have been used to describe this unique form of caries are “occult caries,” “pre-eruptive caries,” and “pre-eruptive intracoronal radiolucent defect.” The term pre-eruptive has been used because this form of caries is frequently visible in either bitewing or panoramic radiographs prior to any visible entry of the affected tooth into the oral cavity. Figure 2 is a radiograph of the same tooth as Figure 1, but taken at an earlier “pre-eruptive” state. The presence of this dentinal radiolucent area is clearly visible prior to eruption into the oral cavity.
   
Subject prevalence has been reported to be between 2% to 6%, while tooth prevalence has been reported to be between 1% and 2%.2-4  To date, there seems to be inconclusive histopathology and microbiological evidence to suggest an authoritative specific etiology of this form of caries in the pre-eruptive state. In addition, there is some controversy as to the predictability of further progression of these dentinal lesions once these teeth have erupted. Moskovitz and Holan have reported a non-progressive lesion over a long period of time.5 The lack of predictability of these pre-eruptive intracoronal radiolucent defects presents numerous challenges to the pediatric dentist who may choose to monitor or observe the teeth with such lesions or choose to actively excavate and fill teeth with these defects. The advantages and disadvantages of these options need to be clearly articulated to the parents of young patients as well as the parental responsibility that is needed to ensure that their children will indeed be made available for periodic check-ups to monitor any potential progression. Despite the most vigilant professional monitoring, poor oral hygiene and cariogenic diets can increase the risk of harmful oral bacteria finding a pathway to the already existing pre-eruptive caries, thus promoting further progression of this lesion to the pulpal tissues.

The orthodontist’s role in detecting hidden caries

The orthodontist is in an excellent position to be able to detect pre-eruptive or hidden caries. A panoramic radiograph, which, in the authors’ opinion, should accompany all mixed dentition orthodontic examinations, will frequently detect missing or supernumerary teeth, ectopically developing permanent teeth, and pre-eruptive defects or hidden caries. An interesting finding in the Seow et al study was that close to 28% of unerupted ectopic teeth were associated with pre-eruptive dentin defects, either in itself, or on an adjacent tooth.3 Figure 3 is a panoramic radiograph taken as part of a routine orthodontic examination. Note the radiolucent areas inferior to the amelodentinal junction in both the pre-eruptive right and left mandibular permanent second molars.  Here, the orthodontist has an opportunity to communicate these findings to the pediatric dentist as well as share this record. This important communication effort will facilitate an early discussion with the parent about the clinical options available for this patient. Figure 4 is a panoramic radiograph after the eruption of the permanent second molars. Figure 5 is a subsequent panoramic radiograph after the mandibular second molars have been excavated and appropriately filled by the pediatric dentist.
The orthodontist will also be expected to take either “scout” periapicals or a panoramic radiograph during orthodontic treatment to detect any adverse root changes, such as resorption, root positioning (e.g., parallelism of roots in extraction cases), and the location and angulation of any still unerupted teeth. Figure 6 is an example of a mid-treatment panoramic radiograph that was incompletely read by the orthodontist. The presence of a pre-eruptive dentinal lesion associated with the mandibular left second premolar was undetected. The next panoramic radiograph (Figure 7) was taken at the end of treatment (less than 2 years later) in an otherwise well-treated extraction case. Note the progression of this lesion on the mandibular left second premolar. Operative efforts were extensive and involved a pulp-capping procedure for a tooth that might have been restored far more conservatively if the early and smaller lesion had been detected by the orthodontist while he/she was scrutinizing the panoramic radiograph for other more routine orthodontic areas of interest and concern (Figure 8).



Conclusions

The orthodontists, pediatric dentists, or general dentists who might treat young children need to have greater interactivity and communication among them for the benefit of their mutual patients. The early detection of pre-eruptive dentin lesions (hidden caries) is but one example of the consequential need for the sharing of clinician databases and records. The pediatric dentist might rely upon the orthodontist, particularly when the panoramic radiograph taken by the orthodontist might be the first radiograph obtained in the case of special needs patients or others with an exaggerated gag reflex who cannot tolerate routine bitewing radiographs.

It is hoped that the future of both pediatric dentistry and orthodontics will hold a more promising interaction void of traditional territorial academic or professional barriers. With such a meaningful collegial and enlightened interaction, our mutual patients are sure to profoundly benefit.

Bios

Sean C. Adler, DMD, is Clinical Assistant Professor, Department of Pediatric Dentistry, Columbia University School of Dental Medicine.

Elliott M. Moskowitz, DDS, MSd, is Clinical Professor, Department of Orthodontics, New York University College of Dentistry.

Mark S. Hochberg, DMD, is Director Emeritus of Pediatric Dentistry, Interfaith Medical Center, New York.


References

1. Skillen WG (1941) Intra-follicular caries. Ill Dent J 10:307-308.

2. Seow, WK (2000) Pre-eruptive intracoronal resorption as an entity of occult caries. Pediatr Dent 22(5):370-376.

3. Seow, WK (1999) Prevalence of pre-eruptive intracoronal dentin defects from panoramic radiographs. Pediatr Dent 21(6):332-339.

4. Weerheijm KL (1997) Occusal “hidden caries,” Dent Update 24(5):182-184.

5.    Moskovitz M, Holan G (2004) Pre-eruptive intracoronal radiolucent defect: a case of a nonprogressive lesion. J Dent Child 71(2):175-178.