We often get asked about children’s teeth, and what you should do when they start appearing. Dr John Roberts from Weymouth Street Paediatric Dental Care has answered some of the questions that our readers have sent in, and we were really interested to read the answers.

When do milk teeth start to form in the mouth, and at what age and in what order do milk teeth visibly appear?

All of the ‘milk’ or primary teeth begin to form during the fourth month of pregnancy, and start to erupt in the following order: lower central incisors, upper central incisors, lower then upper lateral incisors, first molars, canines and finally the second molars at 20-30 months of age. It should be recognised that there is a normal variation in the age at which teeth erupt, this variation having no significance other than early eruption is often followed by early shedding (exfoliation) of those teeth. Also, there is frequently a different order of eruption than I have given above, again this variation having no other medical or dental significance.

Is it the action of the new teeth coming through that push the milk teeth out of the gums, and at what age and in what order does this happen?

The actual mechanism of tooth eruption is still poorly understood. What is clear is that as the permanent tooth begins to move towards the gum line, it stimulates cells to gradually remove the root of the primary tooth ahead of it. Then, when there is almost no root remaining to hold the baby tooth in position, that baby tooth becomes loose and then falls out. With normal variation the order of loss of primary teeth is as follows:

Lower central incisors then lower lateral incisors, 6-8 years, upper central incisors 7-8, upper lateral incisors 8-9, lower canines 9-11, upper first molars 9-11, lower first molars 10-12, upper canines 10-12, second molars 11-13.

Should I encourage my child to wobble and pull on their baby teeth once they start becoming loose, and what are the dangers of pulling one out before it is ready?

Children react in different ways to the loss of primary teeth, for some it is an exciting process while to others it is scary and painful. In reality it is simply a physiological process, not a pathological one. However, it should also be recognised that when the tooth is ready to be lost it is mobile, and the underside of the tooth can have a fairly sharp edge which can irritate the surrounding soft tissues and cause an inflammation (not an infection). In almost every instance the tooth will be lost spontaneously but it is inevitable that children will play with the tooth, moving it with their tongue or fingers until it comes out. This natural tendency does not need to be encouraged or discouraged, each child will deal with the situation as they think fit. If the tooth is mobile due to the new tooth erupting beneath it, then no harm will come from the child removing it earlier than it would naturally be shed. Occasionally the tooth does not shed in the normal fashion and if that causes the child undue discomfort or seriously impacts upon daily activities, then your dentist can advise whether it should be expediently removed.

Is it dangerous if my child accidentally swallows a baby tooth, while sleeping, for instance?

If this happens the tooth will simply pass through and end up in the loo!

What are the main differences between milk and adult teeth? Why do we need to lose a set to gain a new set?

In general, primary teeth are smaller than the permanent teeth that take their place, especially the molars. They are less highly mineralised i.e. they are ‘softer’, but correspondingly they have a softer diet to contend with, and are not expected to last as long as permanent teeth.

The question of why we have two sets of teeth is an interesting one to which we do not have a definitive answer. One possibility is that for the babies of virtually all mammals to pass through the birth canal the baby has to be small and in particular the head. That means that for primates in particular the skull (and brain and jaws) are under developed. Accordingly the jaws are small and cannot accommodate a set of permanent teeth. Hence there is a set of primary teeth, and in humans only 20 compared with 32 for the adult. These small teeth are adequate for an infant as they rapidly grow on milk and then soft foods until full weaning. The jaws only start to get big enough by late childhood when the larger permanent teeth start to appear.

Are milk teeth susceptible to the problems that occur in adult teeth, and if milk teeth aren’t looked after properly, is the slate wiped clean once the new ones come through?

If we consider dental decay, or caries, then the primary teeth are at least as susceptible as the permanent teeth, and although there is probably a genetic component to caries-proneness, the major causes of decay are diet-related and plaque removal (toothbrushing, flossing, etc.). The child’s teeth need to be thoroughly cleaned every day, by an adult until the age of about seven years, preferably using fluoride-containing toothpaste. The actual amount of refined carbohydrates, sugars, starches, sweetened drinks etc., is nowhere nearly as important as the frequency of intake of those substances; if the child only has those cariogenic foods at the end of a main meal, and none at all between meals, then for most children that will not result in dental decay.

It follows that if the lifestyle that produced decay in the primary teeth is radically altered, then the permanent teeth will remain decay-free. All too often however, that does not happen, and research shows that decay in the primary teeth is a strong indicator that decay will occur in the permanent teeth also.

My child’s adult teeth are coming through asymmetrically. Is it time to start worrying, and is there anything one can do to prevent this while new teeth are coming in?

Frequently the lower incisors erupt behind the still-present primary incisors, giving a double row of teeth. If the primary incisors are mobile, wobbly, then in almost all instances nothing needs to be immediately; given time the primary teeth will fall out and the permanent incisors will be pushed forward by pressure from the tongue. If the situation persists for more than 6-9 months then the dentist may advise extraction of the primary tooth but it is certainly not an emergency. Unnecessary tooth extraction is not good.

If the new teeth are coming into a crowded position, this usually indicates a genetic discrepancy between the tooth size and the jaw size, and that at an appropriate age the child will need a course of orthodontics to align the teeth. Sometimes there is nothing to be done advantageously to deal with this when the teeth first erupt, while at other times judicious early treatment can prevent the need for full orthodontics later. My advice would be to seek advice from your dentist if you are concerned.

When should I start taking my child to the dentist, and how often?

Historically the child had his/her first dental visit at three years of age, as this was when they could reasonably be expected to sit in the dental chair and cope with the examination. Unfortunately for some children this is far too late, and they have many decayed teeth by this age. Indeed, dentists are seeing very many cases of what is termed Early Childhood Caries, or Nursing Bottle Decay, where even before eighteen months of age there are eight or more decayed teeth.

Therefore dentists would like to examine children at about twelve months of age; this is done with the child on the mother’s lap in the dental chair, with the child’s head in the dentist’s lap. The dentist can hopefully find no cavities and simply give the mother advice on how to maintain this healthy state, or else take steps to minimize the existing damage. Sometimes, however the decay is so advanced that we need to extract at that early age.

A review examination is advisable at approximately six month intervals. The child’s retention of oral health advice is frequently short lived, and a six-monthly reminder by the hygienist never goes amiss. Also, because the primary teeth are smaller and softer than permanent teeth, then when decay starts it can progress more quickly to the stage when an abscess develops. Frequent examinations, with x-rays taken at appropriate intervals can enable decay to be detected, and therefore to be treated with smaller, less intrusive, restorations.

If my child requires braces – what’s the process of acquiring them, and what types are used for which problems, and for how long?

Orthodontic treatment for children is usually to correct the position of teeth that are crowded, or in cross bite, or where the upper incisors protrude or are behind the lower incisors. In these situations the child will need to be referred by the general dentist to a specialist orthodontist for assessment and, if necessary, treatment. The most effective appliance used, and the one that gives the orthodontist best control over tooth movement is the fixed type. Sometimes the problem can be addressed by a removable appliance, or with clear removable splints e.g. Invisalign. Commonly the period of active treatment is around twenty-one months, to be followed by a period of retention to make sure the teeth remain in a stable position.

Should my child’s hygiene routine change as they grow older?

To the extent that the aim is complete plaque-removal, then the simple answer is no. However, as the child matures then so does his/her manual dexterity, and thus ability to use the brush, floss, interdental brushes, etc. The dental hygienist can assess the way that oral hygiene is being attempted and then suggest changes to those techniques to make them more effective. Sometimes an electric toothbrush will be best and sometimes a manual one. There is not just one brushing technique that is appropriate for each child at all stages of development; the hygienist can suggest a change of technique for each situation.

Drs Noushin Attari, John F Roberts & Liege Lourenço
Weymouth Street Paediatric Dental Care LTD
33 Weymouth Street
London W1G 7BY
Web: www.paediatric-dentistry.co.uk
E-mail: info@paediatric-dentistry.co.uk
Tel: 0207 580 5370
Fax: 0207 636 3094