Risk Groups
Risk age groups
Recent studies have shown that carious lesions are initiated more frequently at specific ages. This applies particularly to children but also to adults. In children, the key-risk periods for initiation of caries seem to be during eruption of the permanent molars and the period during which the enamel is undergoing secondary maturation.
In adults, most root caries develops in the elderly, partly because of the higher prevalence of exposed root surfaces.
Key-risk age group 1: Ages 1 to 2 years Studies by Kohler et al (1978, 1982) showed that mothers with high salivary MS levels frequently transmit MS to their babies as soon as the first primary teeth erupt, leading to greater development of caries. Other studies have shown that 1-year-old
babies with plaque and gingivitis develop several dental carious lesions during the following years, while babies with clean teeth and healthy gingivae, maintained by regular daily cleaning by their parents, remain caries free (Wendt et al, 1994). It was also shown that the practice of giving infants sugar-containing drinks in nursing bottles at night increases the development of caries (Wendt and Birkhed, 1995).
In another investigation, Grindefjord et al (1995) studied the relative risk (odds ratio) that 1-year-old infants would develop caries by the age of 3.5 years: Those with poor oral hygiene, bad dietary habits, salivary MS, little or no exposure to fluoride, and parents with a low educational level or an immigrant background were at 32 times greater risk than were children without the corresponding etiologic and external risk factors. The importance of establishing good habits as early as possible, and of postponing or preventing bad habits, should not be underestimated.
In addition, the enamel of erupting and newly erupted primary and permanent teeth is at its most caries-susceptible stage until completion of secondary maturation (Kotsanos and Darling, 1991). In 1- to 3-year-old infants, the specific immune system, particularly immunoglobulins in saliva, is immature. Poor oral hygiene will therefore favor the establishment of cariogenic microflora such as MS.
On average, the permanent teeth in particular erupt 6 to 12 months earlier in girls than they do in boys (Teivens et al, 1996). On this basis, the first-priority risk age groups are expectant mothers and 1 to 2 year olds, starting with girls (Fig 125). To prevent postnatal transmission of cariogenic bacteria and poor dietary habits from mother to child, expectant mothers who are at risk should be offered a special preventive program comprising intensified plaque control (mechanical and chemical) and reduction of sugar intake, to reduce the number of cariogenic microflora.
Key-risk age group 2: Ages 5 to 7 years (eruption of first molars) The pattern and amount of de novo plaque reaccumulation on the occlusal surfaces of the permanent first molars, 48 hours after professional mechanical toothcleaning, was studied in relation to eruption stage by Carvalho et al (1989). Plaque reaccumulation is heavy on the occlusal surfaces of erupting maxillary and mandibular molars, particularly in the distal and central fossae and related fissures. This is in sharp contrast to the fully erupted molars, which are subjected to normal chewing friction.
Abrasion from normal mastication significantly limits plaque formation, and this explains why almost all occlusal caries in molars begins in the distal and central fossae during the extremely long eruption period of 14 to 18 months. In contrast, fissure caries is very rare in premolars, which have a brief eruption period of only 1 to 2 months.
In addition, the enamel of erupting and newly erupted teeth is considerably more susceptible to caries until secondary maturation is completed, more than 2 years after eruption. However, the caries-reducing effect of fluoride is also about 50% greater in erupting and newly erupted teeth than it is in teeth that have undergone secondary maturation.
The next high-risk age is, therefore, from 5 to 7 years, during eruption of the first
molars (the key-risk teeth), starting with girls (see fig 125). Intensified mechanical
plaque control twice a day with fluoride toothpaste should be performed by the
children’s parents, particularly on the erupting first molars. Home care should be
supplemented at needs-related intervals by professional mechanical toothcleaning and
fluoride varnish. In the most caries-susceptible children, glass-ionomer cement should
be used in the fissures, as a slow-release fluoride agent.
Key-risk age group 3: Ages 11 to 14 years (eruption of second molars)
Normally, the second molars start to erupt at the age of 11 to 11 1/2 years in girls and
at around the age of 12 years in boys. The total eruption time is 16 to 18 months.
During this period, the approximal surfaces of the newly erupted posterior teeth are
undergoing secondary maturation of the enamel and are also at their most caries
susceptible. Therefore, 11 to 14 year olds have not only, by far, the highest number of
intact tooth surfaces, but also the greatest number of surfaces at risk.
Integrated plaque control measures and use of fluoride agents should therefore be
intensified on the approximal surfaces of all the posterior teeth and the buccal
surfaces of the second molars, starting with 11 to 11 1/2-year-old girls (see Fig 125), to
protect intact tooth surfaces and to remineralize incipient lesions. If this program is
maintained throughout the secondary maturation period, and needs-related self-care
habits are established, there is a high probability that the remaining intact tooth
surfaces will remain intact for the individual’s entire life.
Key-risk age groups in young adults and adults
Under certain circumstances, young adults (19 to 22 year olds) may also be regarded
as a risk age group. Most have erupting or newly erupted third molars without full
chewing function but with highly caries-susceptible fissures and mesial surfaces until
completion of secondary maturation of the enamel. In addition, many young adults
leave home to study or work elsewhere, with ensuing changes not only in lifestyle but
also in dietary and oral hygiene habits. They may also be exposed to peer pressure
toward good or bad habits.
Another risk age group among adults is the dentate elderly, most of whom have
multiple restorations with plaque-retentive margins as well as root surfaces exposed
by periodontitis. Regular use of medication with depressive effects on the saliva and
poor oral hygiene and dietary habits further increase the risk for development of
secondary caries and root caries.
