Dentists are urging parents not to fill lunch boxes with sugary treats and juices.
Specialist paediatric dentist Dr Rose-Marie Daly said: "Lunch boxes can be tricky for fussy eaters. It is best to keep fillings in wraps savoury and avoid jams and chocolate spreads.
"Children who have dried fruit and biscuits for lunch are more likely to develop cavities. Cheese and fruit make good snacks. Juice should be limited to one serving per day," said Dr Daly.
She said that milk and water are the only safe drinks to quench thirst and parents should avoid high-energy sports drinks.
Fruit juice has a very high sugar content, higher than fresh fruit, the Tralee-based dentist said.
One of the things she recommends to protect children's teeth are fissure sealants.
"Many parents are unaware of the valuable role fissure sealants can play in protecting their children's teeth from decay," said Dr Daly.
This is a plastic coating which can be applied to form a shield over the chewing surface of the back teeth and helps to prevent tooth decay.
"Fissure sealants do need to be monitored and checked for cracks and leakage. They sometimes need top-ups," she said.
The expert also said that parents should make sure that children have suitable mouth guards for their sports activities.
"Children's teeth should be checked three times by the public health dentist during primary school.
Due to cutbacks and a staffing embargo in the HSE, this may not be happening in some schools, and parents may need to remind the school about them. Parents should contact their local HSE clinic and see what their entitlements are, as this varies from place to place," Dr Daly said.
The Irish Dental Association said that parents should help children aged six and under to brush their teeth twice a day.
It urged parents of children who are starting school for the first time to make sure they follow a good dental health routine from day one.
Meanwhile, Safefood - which offers advice on food safety and healthy eating - said that lunches provide around a third of our daily nutritional needs.
It said that parents should include one or two portions of starch foods in a child's lunchbox ever day. Examples include bread, a roll, bagel or wrap, and ideally choose brown or wholegrain varieties.
In addition, it said that one or more portions of fruit and vegetables should be included, like apple, orange, banana or berries and vegetable sticks.
"Many schools have a healthy lunchbox policy and won't allow foods like crisps, cakes, sweets, cereal bars or chocolate in school lunchboxes, so it's worth checking with your own local school to see what their policy is," a Safefood spokespeson said.
It comes as recent research showed that Irish preschool children, aged between three and five, who watch television recognised twice as many unhealthy food and drink brands as healthy ones.
Dr Cliodhna Foley-Nolan, director of human health and nutrition with Safefood said the influence of the wider marketing environment needs to be considered, as well as the role parents' play in their children's food choices.