Key-risk surfaces
As mentioned earlier, depending on the age and caries prevalence of the population, there may be pronounced variations in the pattern of both lost teeth and decayed or filled surfaces. Figure 130 shows caries prevalence and the pattern of decayed or filled surfaces in 12-year-old children in the county of Varmland, Sweden, in 1964, 1974, 1984, and 1994. The molars are clearly the key-risk teeth. In a toothbrushing population, the key-risk surfaces are the fissures of the molars and the approximal surfaces, from the mesial aspect of the second molars to the distal aspect of the first premolars. Integration of mechanical plaque control by self-care and the use of fluoride toothpaste, supplemented at needs-related intervals by professional mechanical toothcleaning, fluoride varnish, and chlorhexidine varnish should therefore target these key-risk teeth and surfaces, according to the principles discussed earlier in this chapter.
As shown in Fig 130, the mean caries prevalence in 1964 was around 40.0 decayed or filled surfaces, generally involving all the approximal surfaces and occlusal surfaces of the molars and premolars, but also some buccal and lingual surfaces. One mandibular first molar was missing, extracted because of caries. During the following 10 years, toothbrushing and fluoride toothpaste were introduced. As a result, the number of decayed or filled surfaces decreased to about 25.0. The reduction was mainly in carious lesions on the approximal surfaces of the incisors and the buccal and lingual surfaces of the molars and premolars. The separate effects of the toothbrush versus fluoride toothpaste are difficult to estimate.
In 1975, a needs-related plaque control program (both professional and home care) combined with use of fluoride toothpaste and application of fluoride varnish was gradually introduced targeting the key-risk surfaces of schoolchildren. The number of decayed or filled surfaces decreased to 3.0: The reduction occurred on the approximal surfaces of the molars and the premolars. The remaining caries, it is suggested, represents mainly overtreatment of first molar fissures.
Our preventive program for the occlusal surfaces of the molars was initiated in 1984.
In 1994, caries prevalence was less than 1.0 decayed or filled surface. It is predicted that, in 1999, the first group of 19 year olds to have followed the integrated preventive program from birth will have less than 1.0 approximal decayed or filled surface, of which the filled component should account for less than 0.3, because approximal carious lesions without cavitation into the dentin can be treated noninvasively, without restoration.
Figure 131 shows the mean pattern of manifest caries or restorations with or without initial caries (enamel caries) included on the posterior approximal surfaces of a randomized sample of 19 year olds from four counties in Sweden (Forsling et al, 1999). The distal surface of the mandibular right first molar is clearly the most frequently decayed. This is probably because most people are right-handed, and it is well known that in right-handed people the mandibular right linguoapproximal surfaces show the greatest tendency to plaque accumulation and gingivitis.
That the distal surfaces of the second premolars constitute a relatively high percentage
of carious surfaces may be explained as follows: The wide mesial surfaces of the first
molars are frequently carious and exposed to cariogenic microflora when the second
premolars erupt. In caries-susceptible (C2 or C3) individuals, it is difficult to achieve
successful arrest of such enamel lesions during the short period of eruption (1 to 2
months) of the second premolars, and lesions are sometimes unrestored. Until
completion of secondary maturation of the enamel, the environment is extremely
unfavorable for the newly erupted distal surfaces of the second premolars.
Figures 132, 133, 134, 135, and 136 show the pattern of intact, decayed, filled, and
missing surfaces occlusally, mesially, distally, buccally, and lingually in a randomized
sample of 50 year olds in 1988 in the county of Varmland, Sweden (Axelsson et al,
1988, 1990). While almost no intact occlusal surfaces exist (Fig 132), close to 100%
of the lingual surfaces of the mandibular incisors are intact (Fig 136). The lingual
surfaces constitute the highest percentage of intact surfaces, closely followed by the
buccal surfaces (Fig 135). Of the approximal surfaces, the mesial and distal surfaces
of the first molars and maxillary premolars have the lowest percentage of intact
surfaces (5% to 10%), followed by the mesial surfaces of the second molars and the
distal surfaces of the second mandibular premolars (Figs 133 and 134). The gracile
mandibular incisors have by far the highest percentage of intact approximal surfaces
(about 70%).
