James L. Leake, D.D.S., M.Sc., DDPH, FRCD(C):
This is a review of studies on diagnosing, predicting, and intervening in the disease known as root caries that may help clinicians communicate information for their decisions on care to patients.
Questions Addressed in This Review
- What is the natural history of root caries among North American populations? Natural history in this case includes definitions of lesions at different stages; the activity of lesions (active, inactive); rate of progression from stage to stage; reversibility under natural conditions of lesions, by stage; and outcome of untreated root caries.
- How accurate and reliable are the methods we have to diagnose active and inactive root caries?
- For persons with root caries, are there differences in outcomes (absolute improvement in number of teeth retained and functional, or relative improvement, or number needing treatment) between subjects randomly assigned to receive therapeutic care and those not receiving such care?
A search strategy was developed by a consultant to the project, and searches of EMBASE and MEDLINE resulted in a database of 807 annotated references. The annotated references were read independently by at least two people to achieve consensus on 94 that were selected for retrieval. The reference lists in those 94 were then checked, and studies that appeared to be related to our questions were added, producing a final database of 162 references.
Ideally, the evidence should have been selected from high-scoring studies with strong design, as described in criteria of the Agency for Health Care Policy and Research (AHCPR). Many studies, however, were both weak in design and of limited value. Since the evidence on management of root caries is rarely supported by more than a few studies, recommendations on how to do so can only be tentative.
Findings on Prevalence
Prevalence estimates of root decayed and filled surfaces (RDFS) were taken from the NHANES III study. The adjusted prevalence for U.S. adults, as measured by those with one or more lesions, was 25.1 percent. Prevalence increased with age, and by age 75, 55.9 percent had one or more lesions. Severity as measured by the mean number of RDFS was 1.2, of which 58.3 percent were filled. As expected, severity was also age-dependent. Women had lower prevalence (23.3 percent vs. 27.1 percent), lower mean scores (1.0 vs. 1.4) and lower proportions filled (50.0 percent vs. 64.3 percent) than men. Among patients age 34 and older, the prevalence was roughly 20 percent less than a person's age. For example, a person age 50 would have a 30 percent probability of having one or more RDFS.
Findings on Incidence
Eight papers met the inclusion criteria for determining the incidence of root lesions (Hand, Hunt, Beck, 1988a; Hand, Hunt, Beck, 1988b; Leske, Ripa, 1989; Wallace, Retief, Bradley, 1988; Lawrence, Hunt, Beck, 1995; Lawrence, Hunt, Beck, et al., 1996; Locker, 1996; Powell, Leroux, Persson, et al., 1998). These eight discussed five different investigations (two of the studies each discussed two papers). The studies that lasted 16 to 18 months showed much higher incidence estimates that did the studies lasting 3 years or more. Calculation of a duration/sample-size weighted estimate from the results of the four longest studies showed that 8.2 percent of study subjects would be expected to acquire one or more new root caries in 1 year. Those four studies plus one other showed that, on average, dentate people would be expected to acquire 0.19 new RDFS per year.
Clarkson (1995) added a cautionary note when she pointed out that conventional studies of incidence would not pick up restorations of secondary root caries, leading to an understatement of the actual incidence of lesions by as much as two-thirds.
Description of Root Caries Lesions
Diagnosis of a root caries lesion is established through the use of clinical descriptors. These vary, and are subjective. Clinical description is based on color, texture, surface smoothness, depth of the lesion, and distinctiveness of its border, overlayed with a judgment on whether the lesion is active or inactive. Variability in the diagnostic criteria, and the question of whether restored roots are included, strongly affect estimates of the prevalence and severity of root caries lesions (Katz, 1980; DePaola, Soparker, Kent, 1989; Aherne, O�Mullane, Bennett, 1990; Stamm, Banting, Imrey, 1990; Banting, 1993; Fejerskov, Baelum, �stergaard, 1993). The variability in diagnostic criteria limits validity because lesions which apparently "reverse" can be either true reversals or examiner error (Lawrence, Hunt, Beck, et al., 1986; Beck, Lawrence, Koch, 1995).
Katz (1986) defined active and inactive lesions, but that was a statement of consensus.
Billings (1986) developed a staging classification, termed a "severity index," of root caries lesions as follows: Grade I (incipient), Grade II (shallow), Grade III (cavitation), and Grade IV (pulpal). This index, however, was not derived from longitudinal studies of the same teeth in the same individuals.
Five articles provided material for the evidence table on diagnostic systems. The evidence indicates that practitioners have little alternative but to use systems for diagnosing root caries lesions that have low reliability and whose accuracy is unknown. While there is little to recommend any one system over the others, the texture (soft/hard) components of the Billings (1985) and the Hellyer (1990) systems have at least been shown to correspond to histopathology findings (Schupbach, Guggenheim, Lutz, 1990) and penetration by micro-organisms (Beighton, Lynch, Heath, 1993).
Therapy for Root Caries
Seven studies that dealt with remineralization of a tooth with a root caries lesion are included in the evidence table (Billings, Brown, Koster, 1985; Wallace, Retiel, Bradley, 1993; DePaola, 1993; Schaehen, Keltjens, Van Der Hoeven, 1991; Emilson, Ravald, Birkhed, 1993; Johansen, Papas, Fong, et al., 1987; Nyvad, Feyerskov, 1986). The available evidence supports remineralizing with fluoride rinses and, somewhat more tentatively, with fluoride gels and varnishes or chlorhexidine varnish. Also offered as a treatment option was recontouring before remineralizing with fluoride. However, the efficacy of recontouring followed by fluoride treatment was only demonstrated in six people with a total of 13 lesions.
Evidence on restoration of lesions is even more tentative. No studies were found that compared methods of restoring root caries over what would be considered a sufficiently long term. Of the four studies in the evidence table (Billings, Brown, Koster, 1985; Levy, Jenson, Doering, et al., 1989; Duke, Robbins, Snyder, 1991; Sheth, Lesen, Wefel, et al., 1988), the longest was 3 years in duration; the only controlled comparison ran for 1 year. The very limited data suggest that dentists may restore root caries with composite resins, although conventional practice may allow glass ionomer or even amalgam restorations (though no studies are listed).
Generally, studies on the management of root caries do not offer strong evidence on how to care for patients. They are few in number, and they are compromised either in design or duration. The literature is so limited that the issue of which approaches might be more appropriate in terms of patient preference, costs, and efficiency cannot be addressed. Research is needed to validate the accuracy of current diagnostic methods, provide evidence on the efficacy of therapeutic measures through more rigorous designs extending over longer periods, and address the issue of patient-based measures of outcomes.
Agency for Health Care Policy and Research. Clinical practice guidelines: acute pain management�operative or medical procedures and trauma.: Department of Health and Human Services, 1992.
Aherne CA, O�Mullane D, Barrett BE. Indices of root surface caries. J Dent Res 1990;69:1222�6.
Banting DW. Diagnosis and prediction of root caries. Adv Dent Res 1993;72:80�6.
Beck JD, Lawrence HP, Koch GG. A method for adjusting caries increments for reversals due to examiner misclassification. Comm Dent Oral Epidemiol 1995;23:321�30.
Beighton D, Lynch E, Heath MR. A microbiological study of primary root-caries lesions with different treatment needs. J Dent Res 1993;72:623�9.
Billings RJ. Restoration of carious lesions of the root. Gerodontology 1986;5:43�9.
Billings RJ, Brown LR, Kaster AG. Contemporary treatment strategies for root surface dental caries. Gerodontics 1985;1:20�7.
Clarkson JE. Epidemiology of root caries. Am J Dent 1995;8:329�34.
DePaola PF. Caries in our aging population: what are we learning? In: Bowden GH, Tabak LA, eds. Cariology for the nineties. Rochester, NY: University of Rochester Press, 1993:25�35.
DePaola PF, Soparkar PM, Kent RL Jr. Methodological issues relative to the quantification of root surface caries. Gerodontology 1989;8:3�8.
Duke ES, Robbins JW, Snyder DS. Clinical evaluation of a dentinal adhesive system: three-year results. Quintessence Int 1991;22:889�95.
Emilson CG, Ravald N, Birkhed D. Effects of a 12-month prophylactic programme on selected oral bacterial populations on root surfaces with active and inactive carious lesions. Caries Research 1993;27:195�200.
Fejerskov O, Baelum V, Ostergaard ES. Root caries in Scandinavia in the 1980�s and future trends to be expected in dental caries experience in adults. Adv Dent Res 1993;7:4�14.
Hand JS, Hunt RJ, Beck JD. Coronal and root caries in older Iowans: 36-month incidence. Gerodontics 1988;4:136�9.
Hand JS, Hunt RJ, Beck JD. Incidence of coronal and root caries in an older adult population. J Public Health Dent 1988;48:14�9.
Hellyer PH, Beighton D, Heath MR, Lynch EJ. Root caries in older people attending a general dental practice in East Sussex. Br Dent J 1990;169:201�6.
Johansen E, Papas A, Fong W, Olsen TO. Remineralization of carious lesions in elderly patients. Gerodontics 1987;3:47�50.
Katz RV. Assessing root caries in populations: the evolution of the root caries index. J Public Health Dent 1980;40:7�16.
Katz RV. The clinical identification of root caries. Gerodontology 1986;5:21�4.
Lawrence HP, Hunt RJ, Beck JD. Three-year root caries incidence and risk modeling in older adults in North Carolina. J Public Health Dent 1995;55:69�78.
Lawrence HP, Hunt RJ, Beck JD, Davies GM. Five-year incidence rates and intraoral distribution of root caries among community-dwelling older adults. Caries Res 1996;30:169�79.
Leske GS, Ripa LW. Three-year root caries increments: implications for clinical trials. J Public Health Dent 1989;49:142�6.
Levy SM, Jenson ME, Doering JV, Sheth JJ. Evaluation of a glass ionomer cement and a microfilled composite resin in the treatment of root surface caries. Gen Den 1989;37:468�72.
Locker D. Incidence of root caries in an older Canadian population. Comm Dent Oral Epidemiol 1996;24:403�7.
Miller AJ, Brunelle JA, Carlos JP, Brown LJ, L�e H. Oral health of United States adults: the national survey of oral health in U.S. employed adults and seniors: 1985-1986. Washington, DC: U.S. Department of Health and Human Service, Public Health Services, National Institutes of Health; 1987. p.168.
Nyvad B, Fejerskov O. Active root surface caries converted into inactive caries as a response to oral hygiene. Scand J Den Res 1986;94:281�4.
Powell LV, Leroux BG, Persson RE, Kiyak HA. Factors associated with caries incidence in an elderly population. Comm Dent Oral Epidemiol 1998;26:170�6.
Schaeken MJ, Keltjens HM, Van Der Hoeven JS. Effects of fluoride and chlorhexidine on the microflora of dental root surfaces and progression of root-surface caries. J Dental Res 1991;70:150�3.
Schupbach P, Guggenheim B, Lutz F. Histopathology of root surface caries. J Dent Res 1990;69:1195�204.
Sheth JJ, Jesen ME, Wefel JS, Levy SM. Restoration of root caries with dentinal bonding agent and microfilled composite resin: 1-year clinical evaluation. Gerodontics 1988;4:71�7.
Stamm JW, Banting DW, Imrey PB. Adult root caries survey of two similar communities with contrasting natural water fluoride levels. J Am Dent Assoc 1990;120:143�9.
Wallace MC, Retief DH, Bradley EL. Incidence of root caries in older adults. Hawaii Dent J 1988;19:8.
Wallace MC, Retief DH, Bradley EL. The 48-month increment of root caries in an urban population of older adults participating in a preventive dental program. J Public Health Dent 1993;53:133�7.