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Modern Concepts of Caries MeasurementCentre for Clinical Innovations and Dental Health Services Research Unit, University of Dundee, The Mackenzie Building, Kirsty Semple Way, Dundee DD2 4BF, Scotland, UK; n.b.pitts{at}dundee.ac.uk
ABSTRACT Following the consideration of several recent systematic and other reviews, there is a growing professional and scientific consensus that caries measurement methodology in caries clinical trials (CCT) should be updated to reflect progress made elsewhere in cariology. In this paper, therefore, "modern" means accepted in contemporary dental research and dental practice on the basis of sound research evidence—not necessarily new or requiring the use of new technology. Caries measurement should be seen in the context of the objectives of modern clinical caries management and the continuum of disease states, ranging from sub-surface carious changes through to more advanced lesions. Measurement concepts can be applied to at least three levels: the tooth surface, the individual, or the group/population. All are relevant to CCTs. Modern clinical caries management can be seen as comprised of seven discrete but linked steps (Steps 2, 3, and 4 are directly concerned with measurement.): (1) ‘Caries detection’ represents a yes/no decision as to whether caries is present; (2) lesion measurement assesses defined stages of the caries process, taking into account the histopatholgical morphology and appearance of different sizes and types of lesion and the diagnostic threshold(s) being used; (3) lesion monitoring by repeated measures at a series of examinations is used when lesions are less advanced than the stage judged to require operative intervention (A comparison of serial measurements permits the efficacy of preventive care aiming either to arrest or to reverse the lesion to be assessed.); (4) caries activity measures would be very valuable, but are relatively poorly developed and tested at present; (5) diagnosis, prognosis, and clinical decision-making are the important human processes in which all the information obtained from steps 1 to 4 is synthesised; (6) interventions/treatments, both preventive and operative, are now routinely used for caries management; and (7) outcome of caries control/management assesses caries management by examining evidence on the long-term outcomes. A challenge for the future is to define a range of optimal caries measurement methods—in use or in development in recent trials, in clinical practice, and/or in caries epidemiology—that will best contribute to more efficient, modern caries clinical trials.
Key Words: caries measurement • caries detection • caries monitoring • caries actvity INTRODUCTION This paper seeks to outline modern concepts of caries measurement and set these within the framework of contemporary, evidence-based, clinical caries management. This is in line with the first objective of the International Consensus Workshop on Caries Clinical Trials (ICW-CCT), which is to "critically review modern caries definitions and measurement concepts" and is of key importance in setting the scene for the design of appropriate, efficient, high-quality clinical trials of caries-preventive agents and procedures relevant to dental practice in the 21st century. This paper builds on the findings of several recent systematic reviews conducted for the National Institutes of Health Consensus Development Conference on Dental Caries (Horowitz, 2004) and other purposes (Ismail, 1999) as well as other reviews, both pre-published (Ismail, 1997; Kingman and Selwitz, 1997; Pitts, 1997a,b, 2001) and undertaken for this Workshop (Featherstone, 2004; Ismail, 2004; Kidd, 2004; Stamm, 2004). These indicate that there is a growing professional and scientific consensus that caries measurement methodology in caries clinical trials (CCT) should be updated to reflect progress made elsewhere in the science of cariology and in clinical caries management. DEFINITION OF TERMS For the purposes of this paper and the ICW-CCT, terms are defined as follows: "Modern" means accepted in contemporary dental research and dental practice on the basis of sound research evidence. It does not necessarily mean new, nor does it require the use of new technology. This is because several of the caries measurement concepts which have been developing and in use in other areas of dentistry for some years have not yet been adopted in the caries clinical trials (CCT) arena, which (in terms of core caries measurement methods) has apparently stagnated. There is a growing consensus that CCT methodology should be updated and refined to reflect these modern concepts and more recent, international, research evidence (Horowitz, 2004; Stamm, 2004). "Concepts" of caries measurement should be seen as theoretical frameworks based upon both synthesized evidence and contemporary practice. These are framed in the context of the objectives of modern caries management and from the perspective of what is needed to fulfill the ICW-CCT mission—that is, to reach consensus about the designs of protocols for caries clinical trials, which are scientifically acceptable as pivotal evidence of the anti-caries efficacy of oral care products. "Caries" has been defined in many ways in the literature. Modern evidence reveals that there is a continuum of disease states ranging from subclinical, subsurface changes through to more advanced, clinically detectable subsurface caries (with so-called "intact" surface layers), to various stages of more advances lesion with microscopic and later macroscopic cavitation of enamel and significant involvement of dentin (Featherstone, 2004; Kidd, 2004). Therefore, dental caries is more than just a "cavity"; it is a disease process. Caries "Measurement" has to do with looking at how defined stages of the caries process are quantified, graded, and recorded for results to be used in assessing the outcome of a Caries Clinical Trial. The measures have to be compatible with what is known of the caries process and the intrinsic limitations of the diagnostic modalities used. They should also be compatible with the objectives of modern clinical caries management. CARIES MEASUREMENT IN THE CONTEXT OF MODERN CLINICAL CARIES MANAGEMENT Caries management and measurement concepts can be applied to at least three levels: the tooth surface and the individual or the group/population level. All are relevant to CCTs. Traditionally, caries is recorded (and measured) at the level of the individual tooth surface or caries predilection site. This has logical advantage from the point of view of capturing as much information about changes in the caries process as possible during the trial, but only if this information is subsequently used fully in the analysis. Often, data on transitions between caries status over time measured in trials at the individual surface level seem not to have been used in final analyses of trial outcomes. Examination of caries outcomes by consolidating caries measures to the level of each individual has both clinical and statistical attractions and can help explain and describe the performance of interventions, while ultimately the result of the trial will depend upon appropriate measures being compared across randomly selected trial groups. (These aspects are considered further in other papers in the series). For this paper, modern clinical caries management concepts can be seen as comprised of seven discrete but linked steps: (1) caries detection; (2) lesion measurement; (3) lesion monitoring by repeated measures; (4) caries activity measures; (5) diagnosis, prognosis, and clinical decision-making; (6) interventions/treatments; and (7) outcome of caries control/management. Since caries measurement should be seen in the overall context of clinical disease prevention and management, each of these steps will be outlined below, but steps 2, 3, and 4 (which are directly concerned with caries measurement) will be considered in greater detail.
(1) Caries Detection
(2) Lesion Measurement
‘Diagnostic threshold’ is a term that describes the cut-off level used in an arbitrary decision of what to classify as diseased and what to classify as ‘sound’. This can be represented in the form of an ‘iceberg’ (Fig. 1
As the iceberg metaphor reveals, the choice of diagnostic threshold used can have a profound effect on the magnitude of caries recorded, reported, and used in analyses (Rimmer and Pitts, 1991). It should also be appreciated that at the iceberg’s base there is a large number of initial lesions, only some of which can be detected with existing or new diagnostic aids. Although traditionally used relatively rarely in pivotal analyses, clinical caries measures involving "pre-cavitation" lesions have in fact been reported in caries clinical trials since at least 1965 (Marthaler, 1965) and have been described and used in clinical research and practice for a very long time before that (Backer-Dirks et al., 1951; Ismail, 2004). In recent years, in addition to clinical visual/visuo-tactile examinations, bitewing radiography and fiber-optic transillumination (FOTI), a range of newer technologies has also been used to produce (potentially) more sensitive measures with which to assess lesions. The need for non-cavitated (or ‘pre-cavitated’) enamel lesions to be detected and measured has been set out many times over many years (e.g., Backer-Dirks, 1961; Marthaler, 1984; Nielson and Pitts, 1991; Ismail, 1997; Pitts, 1997a,b, 2000, 2001; Fejerskov and Baelum, 1998). Caries measurement systems enabling this to be carried out, although diverse in their detail (Ismail, 2004), have also been available for many years (e.g., Backer-Dirks et al., 1951; Marthaler, 1966; Ismail et al., 1997; WHO, 1979; Nyvad et al., 1998; Ismail, 1999; Fyffe et al., 2000b; Pitts et al., 2000). In most of these measurement systems, lesions have been graded on the basis of the depth of penetration of the caries through the tooth tissues. Recently, there has been a greater focus on grading both initial and more developed lesions on the basis of surface continuity (or so-called ‘macroscopic cavitation’). The methodological issues which need to be recognized when measurement methods are compared include: the ambiguity and incompatibility of some grading systems with regard to lesions around the enamel dentin junction, clarity as to the use of clinical (as opposed to histological) estimates of dentinal involvement, and defining clearly what constitutes ‘non-cavitated’ lesions in both enamel and dentin (Pitts, 1997a).
(3) Lesion Monitoring by Repeated Measures Attempts at monitoring small changes in lesions over time led to a recognition of the need to measure such changes with objective and, it was hoped, more reproducible and quantitative methods (Pitts, 1984b; Angmar-Månsson and ten Bosch, 1987). Initial attempts to use computer-aided image analysis of serial radiographic images showed promise (Pitts, 1986; Pitts and Renson, 1987), but these still used ionizing radiation and were not developed commercially. The continuing need for new quantitative methods with which to make serial assessments of caries lesions has spurred a broad series of attempts to develop aids to the diagnosis and monitoring of lesions (these are referred to in later publications from the ICW-CCT).
(4) Caries Activity Measures
(5) Diagnosis, Prognosis, and Clinical Decision-making
(6) Interventions/Treatments
The very small, background, subclinical lesions which are in overall balance between de- and remineralization need no active care (NAC) over and above normal caries control measures. A sizeable proportion of the iceberg is amenable to preventive care, and this is what is advised (PCA), while the status of existing lesions is monitored over time to assess the success of combined professional and self-care. For larger lesions which extend into dentin and are progressive and/or cavitated, typical care advised will consist of both preventive and operative elements (PCA + OCA). This is because without modification of the original etiological factors driving the caries process, restorations can never be considered as effective in the long term, since the caries process will continue to be active. Although this approach to clinical caries management, encompassing both primary and secondary prevention, is thought of by some as new (SIGN, 2000) and is often termed ‘modern’, it has in fact been advocated and used for very many years by numerous authorities and dentists in a variety of countries (see Pitts, 1992, 1997a,see Pitts, b; Pitts and Longbottom, 1995; Verdonschot et al., 1999; Ismail, 2004). Changes in disease presentation, particularly on occlusal surfaces (Kidd et al., 1993), provide an increasing challenge to the detection, measurement, and diagnostic steps in the modern caries management process. Similarly, the beneficial effect of the more widespread use of pit and fissure sealants means that new methods are needed to make consistent and reliable assessments of surfaces that become sealed (Deery et al., 2001). Changes in dental epidemiology and public health are also reflecting the modern methods of measuring and controlling dental caries at the population level. Epidemiological data collected for African and Chinese populations over a decade (Manji et al., 1991; Luan et al., 2000) show that monitoring clinically detected enamel lesions over a long period is feasible and generates useful new knowledge about lesion behavior in populations, as well as for caries management in individuals. In Denmark, national statistics collected at the D1 measurement threshold have been used to show the total burden of disease in the population (Poulsen and Sheutz, 1999).
(7) Outcome of Caries Control/Management INTEGRATING THREE ASPECTS OF MODERN CARIES MEASUREMENT
From the above, it can be seen that modern caries measurement concepts now embrace three complementary domains, shown diagrammatically in Fig. 3
INCORPORATING THE BEST EVIDENCE ON CARIES MEASUREMENT INTO MODERN CARIES CLINICAL TRIALS A challenge for the Workshop is to define a framework for identifying and utilizing optimal measurement methods that will best contribute to more efficient, modern caries clinical trials. These may be in use (or in development) in recent clinical trials, in clinical practice, and/or in caries epidemiology. To develop a basis for consensus on the issue of caries measurement concepts in line with the ICW-CCT Mission (to reach consensus about the designs of protocols for caries clinical trials, which are scientifically acceptable as pivotal evidence of the anti-caries efficacy of oral care products) and its first Objective (to critically review modern caries definitions and measurement concepts), the following draft consensus statement is proposed: "In light of the evidence reviewed, both here and elsewhere, pertaining to modern caries definitions and measurement concepts, the participants support a statement recommending that, in future CCT protocols, caries measurement methods are employed which:
This consensus statement on caries measurement systems, refined by discussion at the Workshop, will need to be integrated with those reached later during the meeting which relate to: (a) current and future diagnostic methods and requirements, (b) modern trial designs, and (c) statistical methods to provide pivotal evidence of anti-caries efficacy, to formulate key elements of protocol(s) for shorter and more efficient modern caries clinical trials and a framework for validating them. Continuing research to optimize the specification and performance of caries measurement frameworks for assessing lesions in the Caries Clinical Trial environment is needed. Such systems may, in some cases, be different in detail from those meeting the clinical needs of dentists. These frameworks should, however, still be compatible with beneficial clinical outcomes for patients.
ACKNOWLEDGMENTS The author is indebted to many collaborators and colleagues who have given generously of their time and expertise working on many of the studies cited in and contributing to this paper. In particular, I recognize contributions from Dr. Longbottom and my co-workers from both the Centre for Clinical Innovations and the Dental Health Services Research Unit at the University of Dundee. The support of several grants from commercial and non-commercial sources, as well as core support from the Chief Scientist Office of NHS Scotland, is acknowledged with thanks. The views expressed are those of the author and do not necessarily reflect those of the Scottish Executive Health Department or the Medical Research Council. FOOTNOTES Presented at the International Consensus Workshop on Caries Clinical Trials, Glasgow, Scotland, January 7–10, 2002 REFERENCES
Journal of Dental Research, Vol. 83, No. suppl 1,
C43-C47 (2004) This article has been cited by other articles:
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