Dental caries and oral-health prevention — formative SAQs

SAQ 1 — The toddler with brown front teeth and a bedtime bottle (10 marks, 15 minutes)

A three-year-old is brought for a check. Her mother mentions her upper front teeth have "gone brown" over the last year; she has fallen asleep each night with a bottle of sweetened milk since infancy, and brushing is inconsistent. On examination, the maxillary anterior primary teeth show chalky white spots and brown cavitated lesions, while the lower anterior primary teeth are spared. She is otherwise well, with no swelling or fever. ^[6]

a) State the case definition and name the clinical pattern, explaining why the lower anterior teeth are typically spared. (2 marks) ^[6]

b) Outline the pathophysiology, naming the critical pH for enamel and the dominant organism. (2 marks) ^[7]

c) Detail the prevention ladder you would advise, including the fluoride toothpaste strength and amount for her age. (4 marks) ^[2]

d) Give two reasons the family might be offered silver diamine fluoride for the cavitated lesions, and the single most important side-effect to counsel about. (2 marks) ^[4]

Model answer

The American Academy of Pediatric Dentistry defines early childhood caries as any decayed, missing or filled primary tooth surface in a child 71 months of age or younger; this child's pattern is the classic ECC distribution of smooth-surface caries of the maxillary anterior primary teeth, with sparing of the lower anterior teeth that sit under the tongue and are bathed in protective saliva. ^[6]

Caries is a biofilm-mediated, sugar-driven, dynamically demineralising disease; the nocturnal bottle bathes the upper teeth in a fermentable carbohydrate that an acidogenic plaque, dominated by Streptococcus mutans, ferments to acid, dropping the plaque pH below the critical value of about 5.5 for enamel so that mineral is lost from the tooth. ^[7]

The prevention ladder is to stop the nocturnal bottle (switch to water), brush twice daily with a fluoride toothpaste of at least 1000 parts per million using a pea-sized amount for her age (three to six years), spit rather than rinse, supervise brushing until around seven to eight years, apply fluoride varnish two to four times a year, reduce the frequency of free sugars, and establish a dental home with recall set by caries risk. ^[2]

Silver diamine fluoride is offered because it is non-invasive and painless and arrests around two-thirds of active primary-tooth carious lesions; the single most important side-effect to counsel about is the permanent black staining of the arrested lesion, and it is avoided in documented silver allergy. ^{[4] [12]}