Dental Caries Risk Assessment

Military Medicine, Feb 2006 by Richardson, Peter S

The United Kingdom Defence Dental Agency assesses United Kingdom servicemen as being at low, moderate, or high risk of developing morbidity during the next year, based on the examining dental officer's assessment of their dental status. The most frequent reason for assessing a patient as being at high risk of experiencing a dental emergency is the presence of extensive caries; however, dental officers' perceptions of which caries render a patient at high risk vary considerably. An investigation was carried out with records for Royal Air Force recruits who had been assessed as needing restorative work at their initial dental inspections but for whom this treatment had not been provided for ≥1 year. Intraoral radiographs taken at the initial dental inspection were examined, and the width of apparently sound dentine remaining between the edge of the carious lesion and the pulp was measured. The results indicate that, when there is >2 mm of apparently sound dentine remaining, there is very little risk that the patient will experience symptoms during the next year. Personnel with a carious tooth with

Introduction

The principal reason for establishing military dental services is to minimize the impact of dental morbidity on operational troops. It has been demonstrated repeatedly that the best way to reduce operational morbidity is to provide quality dental services that maintain troops at high levels of dental fitness. However, many nations find that they have neither the dental manpower nor access to operational troops to enable them to achieve 100% dental fitness for deployed forces. It is therefore frequently necessary to make risk assessments regarding which personnel are most likely to develop symptoms, thus prioritizing the provision of treatment.

Most NATO nations use the NATO Standard Agreement 2466 definitions of dental fitness, in which dental fitness category 3 is an assessment that an individual is likely to develop symptoms within the next year; dental fitness category 2 is used for individuals with pathological conditions when it is not considered likely that they will experience problems within the year. One of the weaknesses of the dental fitness categories is that category 3 patients become hidden in category 4 once they go beyond their recall date.

Several articles have investigated the predictive value of category 3 assessment for dental morbidity. Alien and Smith1 found that 85% of deployment sick calls were made by personnel in dental fitness category 3, and McClave and Brokaw2 reported that 50% of personnel identified as class 3 reported to sick call within 12 months. However, Amstutz3 reported that 27% of pathological conditions that subsequently caused morbidity had been charted but not recorded as class 3. Grover et al.4 found that only 34% of personnel identified as high risk reported as dentally sick and these personnel represented only 19% of all emergencies.

The Defence Dental Agency changed to direct reporting of dental risk as previously described.5 However, the first attempt at validation of risk assessment found that, although the sensitivity of the assessment to detect morbidity, especially serious morbidity, was probably as good as it was likely to get using current technology, the false-positive assessment rate was so high that it cast doubt on the usefulness of the system. The predictive values obtained were no better than simple dental fitness category 3 classification, which in the United Kingdom was not meant to be a risk assessment at all.

When the dental risk strategy was introduced, only general guidance regarding how to categorize patients was provided. An attempt was originally made to provide more-detailed guidelines, but these were never issued because they were not evidence based. It was hoped that clinicians' experience would be adequate to make an accurate assessment of risk. It rapidly became apparent from dental officers' clinical profiles that there were major disparities in the percentages of personnel categorized as high risk at inspection. Analysis of morbidity experienced during the United Kingdom deployment to Iraq in early 20036 indicated that -50% of those who developed serious problems had been identified as high risk but the vast majority of personnel categorized as high risk never experienced a problem while deployed.

There are obviously many reasons for categorizing personnel as high risk but by far the most common is the existence of carious lesions, and caries-related morbidity is consistently reported as the principal reason for operational dental emergencies. However, evidence from clinical audits indicated that many personnel with small to moderate-sized (late R3/early R4)7 lesions were being allocated to the high-risk category to give them sufficient priority to receive treatment. Although no one would argue with the idea that the sooner these personnel receive treatment the better, the dental risk categorization is meant to be an indication of dental risk on deployment, and such practices reduce its predictive value.

There are many reports in the literature on rates of progression of caries in dentine,8'12 but there is no information concerning how long it is before a lesion becomes symptomatic. The only true way to assess this would be to inspect a cohort of personnel, record the sizes of their lesions, and provide no treatment until they all developed symptoms. Such a study is clearly unethical; it has not been done in the past and certainly cannot be done in the future. However, to some extent this situation occurs by default with Royal Air Force (RAF) recruits; they have their dental status recorded at their initial dental inspections (IDIs) at the beginning of Phase 1 training at RAF Halton but in many cases receive no treatment for a long time in their Phase 2 training.

Methods

To try to identify which lesions were truly high risk, I visited the Phase 2 training establishment at RAF Cosford. The dental records of all recruits were screened and, if the recruits had not received any routine treatment within 1 year of their IDIs, they were included in the study. Their initial radiographs (taken at RAF Halton) were examined, and an assessment was made of the apparent width of sound dentine remaining between the edges of any radiolucencies and the closest point of the pulp. This was done with the radiographs mounted in standard Defence Dental Agency, dark-framed, radiographie holders masked by a cardboard cutout on an illuminated viewing box, where a clear Perspex ruler, observed under 2.5× magnification, was used to measure the width of the dentine. The intraoperator repeatability of this process had previously been tested by viewing a series of 20 lesions on two separate occasions, allowing time to forget the previous scores. The width of remaining dentine was assessed as being exactly the same on the two occasions for 14 of these lesions; the measurements varied between the first and second examinations for the other six lesions, but in no case did the discrepancy exceed 0.5 mm.