MAVO Year 4 · Nutrition and digestion · Section 12.6

Herbivores, carnivores and omnivores

Tooth structure

A tooth is anchored in the jaw by one or more roots and supporting tissues. Its visible part above the gum is the crown. Dentine forms most of the tooth: it is hard, but softer than enamel, the highly mineralised covering of the crown. Cementum covers the root, helping attach it to the periodontal ligament. The central pulp cavity contains blood vessels and nerves. Gums protect the tissues around the teeth but are not their only means of attachment.

Different diets, different teeth

Herbivores eat plant material, often rich in fibre that is difficult to break down. Many have relatively long digestive tracts or specialised fermentation chambers with microorganisms. Their grinding teeth may have ridges of enamel; canines are often reduced or absent, although there are exceptions.

Carnivores eat animal material. Many have relatively shorter intestines, large canines for grasping and tearing, and sharp shearing teeth called carnassials in groups such as cats and dogs.

Omnivores, including humans, eat both plant and animal foods. They often have teeth with rounded cusps suited to crushing and grinding, incisors for biting and canines of varying size. Digestive-tract length and tooth form are general clues, not universal rules for every species.

Plaque and tooth decay

Dental plaque is a sticky microbial film on teeth, containing bacteria and material from saliva and food. Some bacteria use sugars and produce acids. Repeated acid exposure can remove minerals from enamel and cause tooth decay, forming cavities. Frequent sugary snacks give less time for remineralisation between exposures.

Erosion and dental care

Acids in drinks or food can also directly dissolve tooth minerals: this is dental erosion. Limiting frequent acidic drinks helps reduce exposure. Brushing twice daily with fluoride toothpaste removes plaque and helps protect enamel. Plaque left in place can mineralise into tartar, requiring professional removal. Cleaning between teeth also helps care for teeth and gums.