Chronology Of Teeth Eruption Notes

Chronology Of Teeth Eruption Introduction

Chronological age is derived from one’s date of birth. Knowledge of chronological age is very helpful in determining the dental age. Dental age can also be helpful in deriving the chronological age for legal and forensic purposes. Dental age is estimated as per the eruption and exfoliation status of a tooth in the oral cavity.

The exfoliation and eruption of teeth in most individuals follow a predictable and sequential pattern in the absence of extraneous reasons. Hence, the dental and chronological ages usually correlate. Mild variations in sequence are noticed in a few children and are acceptable when no detrimental effect is evident.

Read And Learn More: Paediatric Dentistry Notes

An acceptable range of variation in eruption time period should be considered before declaring a tooth to be ‘premature’ or ‘delayed’ as per the dental age. An abnormal deviation from the range of normalcy is of diagnostic value as it may be an indicator of a local or a general disturbance.

Further investigations should be done to locate and treat the problem. Delayed dental age in relation to a given chronological age indicates a local problem in a child with good general health. It may be due to reasons such as over-retained deciduous teeth and abnormal eruption path.

A gross variation between the dental age and chronological age indicates a developmental disturbance. A review of the systems is required to locate the problem and treat the same, for example, hormonal disturbance.

Sequence Of Primary Teeth Eruption

The eruption process of the primary teeth happens in a preprogrammed sequential order. It begins from around 6 to 7 months of age and completes by around 30–36 months of age. Each primary tooth seems to guide the path of eruption of its permanent successor.

As each permanent tooth is ready to start its eruption journey towards the alveolar crest to replace its predecessor, the root of the respective primary tooth erodes, eventually leading to the exfoliation of that primary tooth. The exfoliation or shedding process of primary dentition begins around the sixth year of life.

The order of shedding of primary teeth is in accordance with the maturation and eruption pattern of the permanent teeth that replace them. The chronology of the eruption of the primary teeth is depicted.

Sequence Of Permanent Teeth Eruption

Permanent dentition gradually replaces the primary dentition from around 6 years of age. The beginning of the eruption of permanent teeth is marked by the eruption of lower permanent first molars followed by upper permanent first molars.

The first permanent molars erupt at around the sixth year of life and are called sixth-year molars. The exchange of dentition usually begins with the exfoliation of lower primary central incisors and the eruption of lower permanent central incisors.

A period of mixed dentition exists when both primary and permanent teeth are present in the oral cavity. The mixed dentition period lasts for about 6–7 years.

As mentioned earlier, each primary tooth guides the eruption path of its permanent successor. Problems such as the altered path of eruption of permanent teeth and space loss by migration of the adjacent teeth occur when a primary tooth is prematurely lost. This leads to malocclusion like crowding in permanent dentition.

The sequence of exfoliation of primary teeth followed by eruption of permanent teeth is given in Table. The sequence of eruption of permanent dentition is depicted in Figure.

Chronology Of Teeth Eruption Summary

1. Eruption of primary teeth begins from 6 to 7 months and completes by 30–36 months of age.
2. The chronology of the eruption of primary teeth is shown.
3. Permanent teeth replace primary teeth from around 6 years of age.
4. Eruption of permanent teeth begins with the eruption of the first permanent molars at 6 years; hence, the permanent molars are called sixth-year molars.
5. The sequence of eruption of permanent teeth is depicted.