Smooth-surface caries

Several different types of dental caries have been described by clinicians. Specifically these are smooth-surface caries, pit and fissure caries, enamel caries, dentinal caries, secondary caries, early childhood caries and root caries [12], All occur by the same essential mechanism, as described above, and all arise as a consequence of a disturbance to the demineralization-remineralization balance. Attack by organic acids produced by bacteria in the plaque favours demineralization, but the natural remineralization processes of the mouth can reverse this. Certain dietary and hygiene behaviours as well as clinical treatments can enhance this natural remineralization provided they occur early enough in the demineralization part of the process. For example, complexes of casein phosphopeptide with amorphous calcium phosphate have been shown in various studies to be capable of enhancing the remineralization step under certain conditions and in specific groups of individuals [16,17]. These are now available commercially as an anticaries treatment for patients. 

Dental plaque also tends to concentrate fluoride. This could increase possible antienzymatic activity. Some caries protection from this may be expected. Additionally, studies have suggested that topical application of fluoride may also reduce smooth surface plaque, with a resulting beneficial effect on the periodontal tissues. 

Many remineralisation models mimic the situation found on smooth enamel surfaces in the mouth, i.e. appropriate salivary calcium, phosphate and fluoride concentrations and a clean enamel surface with no plaque analogue. Remineralisation of enamel lesions typically occurs during exposure to experimental solutions at neutral pH, whereas demineralisation occurs during exposure to acidic buffers. However, when good oral hygiene is maintained and with the use of fluoride toothpastes, caries is prevalent not on the smooth surfaces of the teeth but on those sites which are difficult to clean and where plaque tends to accumulate i.e. occlusal fissures and approximal surfaces [36], Here, caries is initiated and progresses not on a clean, smooth surface exposed to saliva, but... 

Fig. 15.1 Severe, untreated dental caries. Dental caries initially affects the occlusal pits and fissures of posterior teeth. In severe caries, the smooth surfaces, especially the interdental surfaces of all teeth may be involved...

Lately, May Mellanby and H. Mellanby (1948) have studied anew the correlation between enamel hypoplasia and caries, and the statistics leave little doubt that the hypoplastic tooth, irrespective of the locality in the mouth, can decay more readily and with greater frequency than the corresponding tooth with perfectly smooth surfaces. On other dietaries the correlation may not be significant, as indicated by Marshall-Day s (1944) report of studies in Indian children with well-developed hypoplasia and little caries. 

Streptococcus mutons, a bacterium associated with the production of dental caries, attaches itself to the smooth surface of teeth. The envelopes can be made of polypeptides but are generally composed of polysaccharides. 

Fruit is believed to be beneficial to the teeth on account of its cleansing action and effect in provoking salivation. However, the traditional apple removes plaque only from the smooth surfaces of the teeth which are not prone to caries and may be so acid that the saliva is unable to neutralize it. Cheese appears to have a greater protective effect (page 523). 

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