Diagnostic methods
In typical fissures, and particularly in atypical sticky fissures (see Fig 203), most of the early stages of the lesion are hidden from the naked eye, although in a clean, dry fissure, it might be possible to observe active noncavitated white-spot lesions on the walls. Soon after eruption, most of these lesions are arrested (see Figs 174, 204a-c, 205c) and take up a brown stain from items in the diet. This diagnostic problem was recognized many years ago by GV Black (1908) who wrote:
Very many pits and fissures show evidence of some slight softening in early youth, which is stopped by the coming of immunity or some change of local conditions.
These become dark in color and so remain without further change. These should not be interfered with, as they are just as safe without any filling whatever.
Dentists continue to this day to have difficulty in differentiating active from arrested lesions and usually base their decision on “clinical judgment,” which should include an assessment of a patient’s past caries experience, oral hygiene and dietary habits, salivary function, and likelihood of compliance with a preventive regimen.
None of the aforementioned diagnostic methods has gained universal acceptance, particularly for detection of early occlusal caries. Because occlusal caries today constitutes a major portion of all new lesions in children, its diagnosis assumes considerable importance. Several studies have reported that clinically undetected occlusal lesions, extending well into the dentin, are a serious problem in many communities. In one comparative study of molar lesions that had been clinically undetected (by mirror and probe), 10% more lesions were found with the aid of bitewing radiographs in 1974, whereas 32% more were found in 1982 (Sawle and Andlaw, 1988).
Radiographs, although better than visual inspection alone, are inaccurate in estimating the extent of the carious lesion or in detecting enamel occlusal lesions (D1).
Radiographically, occlusal lesions appear as large, subtle, diffuse dark radiolucent areas in dentin, centrally located under the fissure. Figure 207 shows a limited lesion in dentin (D3) in the mandibular left second molar, and Fig 208 shows a very advanced lesion in dentin, probably involving the pulp (D4), in the mandibular right first molar.
The sensitivity of both visual and clinical-tactile (probing) diagnosis for noncavitated occlusal enamel and dentin lesions is low, but the sensitivity of meticulous clinical visual examination is somewhat better. However, all the clinical diagnostic methods have high specificity (see Fig 200).
Noncavitated occlusal carious lesions are by far the most prevalent lesions in children and young adults; traditionally, these have been restored three times more frequently than have similar lesions on buccal and lingual surfaces. Ideally, noncavitated lesions should be arrested instead of restored. Of great importance is differential diagnosis between active and nonactive lesions and between noncavitated and cavitated lesions.
Probing with explorers
During the past 10 years, the role of explorers in caries detection has become a
controversial issue. Historically, an explorer was essential; if the tip caught in a pit or
fissure, or a cavity, a restoration was indicated. There is no place for such a procedure
in modern caries management: today a noncavitated lesion is managed by
remineralization or by minimally invasive techniques, such as sealants or
microrestorations.
There is also consistent evidence that explorers do not improve the accuracy of caries
diagnosis. Applied with slight force, an explorer could damage a tooth surface,
converting a white-spot lesion into a cavity. Noncavitated lesions in narrow pits are
particularly vulnerable (Figs 209a and 209b). Explorers should not be used to probe
any pit or fissure, or any other tooth surface: their use in stained or noncavitated pits
and fissures is unethical. When required, a blunt periodontal probe may be used, to
remove plaque and debris from the tooth surface prior to examination and to check the
surface texture of a lesion atraumatically.
Lussi (1991) demonstrated the limitations of the explorer as an aid to accurate
diagnosis of occlusal lesions and treatment decisions in an in vitro study. Thirty-four
dentists were instructed to provide diagnoses for 61 teeth and recommend treatment.
The teeth were then histologically prepared and assessed (the gold standard). The
agreement between histologic and clinical diagnoses was determined.
The results showed no difference in diagnostic accuracy between explorer and visual
inspection only. Sensitivity (62%) and specificity (84%) showed that the dentists were
more likely not to treat carious teeth than they were to restore sound teeth.
Approximately 42% of teeth were diagnosed correctly, but the percentage of
“clinically” correct treatment decisions was 73%. It was concluded that, compared to
visual inspection alone, the use of an explorer does not improve the validity of the
diagnosis of fissure caries.
Figures 210a, 210b, 210c, 211a, 211b, 212a, and 212b show the clinical appearance of
the occlusal lesions and the histologic sections of the lesions. Because most of the
extracted teeth were third molars that were only partly erupted or without chewing
function, they exhibited active noncavitated enamel lesions in the fossae surrounding
the fissures.
Radiographs
Although conventional bitewing radiography will significantly improve the potential
for detecting noncavitated occlusal lesions in dentin (D3) (see Figs 200 and 207), there
is some risk of a false-positive diagnosis.
In a Norwegian study (Espelid et al, 1994) 640 dentists were asked to diagnose the
occlusal surface of an intact molar based on a color photograph of the occlusal surface
(Fig 213a) and a radiograph (Fig 213b). Of the participants, 15% diagnosed a dentin
lesion, 53% considered the occlusal surface to be intact, and 32% were uncertain.
They were also asked to suggest therapy appropriate for a 20-year-old patient with
average oral hygiene and dietary habits, presenting with such a lesion: for this
individual, 22% proposed no treatment at all, 23% proposed fluoride treatment, 19%
proposed fissure sealant, and 36% proposed restoration.
In a similar study in vivo (Elderton and Nutall, 1983) 18 subjects underwent clinical
and (bitewing) radiographic diagnosis by 15 dentists. The suggestions for treatment
were wide-ranging; from 20 to 153 occlusal restorations. Only two occlusal surfaces
received an identical diagnosis by all 15 dentists. This study highlighted the need for
considerable improvement in the competence of clinicians, not only with respect to
diagnostic skills, but also in the management of occlusal caries.
To standardize the criteria for diagnosis based on meticulous clinical visual
examination and radiographs, a five-point scale has been proposed (Espelid et al,
1994; Tveit et al, 1994) (Fig 214).
· Grade 1: noncavitated white spot or slightly discolored carious lesion in enamel and
no lesion detected on the radiograph
· Grade 2: some superficial cavitation in the entrance of the fissures, some
noncavitated mineral loss in the surfaces of the enamel surrounding the fissures, and/
or a carious lesion in enamel, detected on the radiograph
· Grade 3: moderate mineral loss with limited cavitation in the entrance of the fissure
and/or a lesion into the outer third of the dentin, detected on the radiograph
· Grade 4: considerable mineral loss with cavitation and/or a lesion into the middle
third of the dentin, detected on the radiograph
· Grade 5: advanced cavitation and/or a lesion into the inner third of the dentin,
detected on the radiograph
New methods
Of the new diagnostic methods, an increase in electrical resistance measurement is a
better predictor of occlusal carious lesions than are meticulous clinical visual
examination, fissure morphology and discoloration, radiographs, and FOTI
examination. The electrical conductance (fixed frequency) method has high sensitivity
and specificity on occlusal enamel (D1) as well as dentin (D3) lesions.
In a recent in vitro study, Ekstrand et al (1997) compared the reproducibility and
accuracy of a new visual scoring system, a new electrical conduction tool (the
Electronic Caries Meter), and conventional radiographs for assessment of the depth of
demineralization on the occlusal surface. After hemisectioning of the teeth, histologic
evaluation was used as the gold standard.
The new visual system appears promising, but takes time to learn and requires the
teeth to be clean. The reproducibility and accuracy of the electric conduction method
was acceptable, while early occlusal lesions were not detectable on radiographs. The
results of this study indicate that both the visual method and the electronic conduction
method, used in conjunction with other relevant clinical observations, can improve the
accuracy of diagnosis of occlusal caries.
