Delayed Tooth Eruption

The first teeth to erupt in your baby’s mouth are lower central incisors (middle front teeth) followed by upper central incisors (middle front teeth), upper lateral incisors (either side of the upper-middle front teeth), lower lateral incisors (either side of the lower middle front teeth), upper and lower first molars (back or rear teeth), canines (between incisors and molars), and lastly by second molars (teeth behind first molars).

The first permanent teeth that replace their predecessor milk teeth are the lower first molars. These are followed by lower central incisors, upper central and lower lateral incisors, upper lateral incisors, lower canines, upper first premolars, lower first and upper second premolars, upper canines and lower second premolars, upper and lower second molars and lastly by third molars.

Tooth eruption is more related to heredity than environmental factors. As it has been mentioned above, the pattern of eruption runs in the family, hence it determines the time of teething to a large extent. The reasons for delayed milk tooth eruption can be local or general.

General factors for delayed tooth eruption are:

• Inheritance
  The pattern and timing of tooth eruption largely depend on the inherited genetic makeup of the child. Hence, some children are early teethers (eruption of teeth earlier than normal), some are normal, while the others are late teethers (eruption of teeth later than normal teething time).
• Nutrition
  Lack of nutrition due to any reason causes a defective overall development of the child. This also leads to slow or faulty development and a late eruption of the child’s teeth.
  Vitamins such as vit A and vit D are very important in tooth and bone development. Deficiency of these severely affects the same.
• Hormonal disorders (Endocrine disorders)
  Disorders or defects in the thyroid, parathyroid or pituitary gland prevents the production and release of hormones which are necessary for the normal growth and development of the child. These can also cause delayed tooth eruption.
• Diseases
  Diseases like HIV, anemia, kidney diseases, cancer, heavy metal poisoning, etc. affect a child’s development and the immune system significantly and cause a delay in tooth eruption too.
• Medications
  Long-term chemotherapy, drugs like phenytoin (used for epilepsy or seizures) cause changes in the body that affect normal tooth and body development.
• Other causes of delayed tooth eruption include low birth weight, tobacco smoke in the environment, developmental defects, etc.

Local factors for delayed tooth eruption include

• Impacted teeth
  Those teeth which get blocked (due to their tilted positions or a lack of jaw space) while pushing through the bone and gums are known as impacted teeth. These teeth fail to come out and are one of the reasons for a delay in tooth eruption.
• Excessively thick gums
  Sometimes, the gum tissue grows excessively thick (known as fibrosis or hyperplasia) and prevents the tooth to push through the same and erupt in the mouth.
• Supernumerary teeth 
  Presence of an extra tooth in the place of a tooth which is about to erupt reduces the available space in the jaw.
• Injury
  Injury or trauma at the site of tooth eruption either due to surgery, or accident, or a sudden blow to the jaws can cause damage to the tooth buds in the bone. This can prevent the development of a tooth, and hence prevent its appearance in the mouth.
• Ankylosis
  Sometimes, the bone surrounding the tooth or near the roots of the tooth might get hardened and prevents eruptive movements of the tooth.
• Ectopic eruption
  The eruption of the tooth at a place other than its expected site of eruption is known as an ectopic eruption. It can occur due to tilted position or displacement of the tooth bud from its original position.
• Odontogenic tumours
  These are the tumours which arise from the lining that forms the tooth buds. The tooth may sometimes be involved and get surrounded by the tumour mass. This tumour prevents the eruption of the involved tooth and causes a delay in its eruption.
• Radiation damage
  Exposure to therapeutic radiation or accidental exposure to large doses of radiation may cause defective development and eruption process of the teeth.
• Oral Clefts
  In this condition, a cleft is present either on the lips or on the palate. Clefts cause displacement, damage, or non-development of tooth buds, thus delaying the eruption process. Read more: Cleft lip and palate causes

Besides the above-mentioned causes, delayed eruption of permanent teeth has other causes as well. These causes are as follows:

• Early loss of a milk tooth
  If the milk tooth of your baby sheds before its normal time then the period between the shedding and the eruption of the permanent tooth will be long and you might think that it is delayed.
  Also, early loss of a milk tooth causes changes in the positions of the adjacent teeth, leading to the loss of space for the permanent tooth to come. It gets stuck inside the bone and may lead to a delayed eruption.
• Retained milk tooth
  Milk teeth usually dissolve in the bone when the permanent tooth beneath them applies pressure on them when it starts erupting. Sometimes, the milk tooth roots may not resorb. As a result, the milk tooth fails to shed and the permanent tooth fails to erupt.
• Harmful habits of the child
  Some children have a habit of constantly touching their teeth with their hands, tongue or other objects. This causes a change in the position of milk teeth and may cause obstruction in the path of an erupting permanent adult tooth.