Modern medicine explains clearly why fruit can leave teeth sensitive and uncomfortable, clarifying principles that could not be fully detailed in the era of the Donguibogam.
The protective outer layer of the tooth is enamel. As the hardest tissue in the human body, enamel shields teeth from external irritation and bacteria. However, it remains vulnerable to acid. Fruits contain various organic acids, including citric acid, malic acid, and ascorbic acid. When these acids contact the tooth surface, they dissolve the minerals within enamel, such as calcium and phosphoric acid, in a process known as demineralization. Demineralization accelerates sharply when surface pH drops below 5.5. Citrus fruits such as oranges and lemons have a low pH between 2.5 and 4.0, which can directly affect enamel. Over time, progressive enamel loss can lead to dental erosion, causing surface pits or wear on biting surfaces.
Sugar adds a second factor. Fruits provide sugars such as fructose, glucose, and sucrose, which feed cariogenic bacteria such as Streptococcus mutans residing in the oral cavity. As these bacteria ferment sugars, they produce lactic acid, another agent that demineralizes enamel. The organic acids from the fruit combined with bacterial lactic acid heighten the overall risk of dental caries.
Saliva normally neutralizes acid and clears residual sugar. Grazing on fruit frequently or holding it in the mouth reduces the time saliva has to cleanse the teeth, accelerating potential damage. Saliva buffers acid and supports remineralization to restore weakened enamel. Individuals with reduced saliva flow are particularly susceptible.
In addition, conditions like gastroesophageal reflux disease allow gastric acid to travel up the esophagus into the oral cavity, directly eroding enamel. When sensitivity persists despite regular brushing, it helps to evaluate how fruit is consumed and whether internal concerns such as acid reflux are contributing factors.
