Chronology of the Dentition 2 PDF

Preview

Summary

lecture notes ...

Description

1 DEN 4412 CHRONOLOGY OF THE DENTITION As you know, primary teeth develop and erupt into the mouth in an orderly sequence over the first few years of life. For a period of time the entire dentition is made up of primary teeth. As the body and face continue to grow, primary teeth are no longer adequate to serve the individual =s needs. Primary teeth are exfoliated and replaced by the eruption of the permanent teeth which began development shortly after birth. In a normal dentition the growth and replacement of teeth occurs according to a predictable schedule and in an orderly sequence. Disturbances which alter the timing or the order of exfoliation of primary teeth and eruption of permanent teeth can affect the structure and function of the permanent dentition. We establish normal eruption patterns based on statistical averages computed over a large number of cases. There are individual differences in the timing and order of tooth development and eruption which are perfectly normal and no cause for concern. Individuals whose __________________________ is very different from the normal, or average, may require assessment to rule out possible problems. If factors contributing to the abnormal growth pattern are discovered, then appropriate treatment interventions can be initiated. Dental anatomy texts provide you with detailed information about the development (i.e., the initiation of calcification and crown completion) and eruption of both primary and permanent teeth. It is important that you keep this information handy as a reference. It is even more important for you to have some basic information about eruption patterns in mind each time you examine a child. Knowledge of the average eruption pattern and sequence helps you to identify the teeth that are present in the child’s mouth. You should also be able to assess the child’s dental development in terms of his/her ___________________________ to determine whether or not dental development is proceeding normally. If a child presents with a very different sequence or timing of tooth eruption you should be able to alert the dentist and the child’s parents to the need for further assessment.

Advanced Dental Anatomy, Course Supplement. C. Thom and D. Dufresne

2 General Facts about Tooth Eruption Every individual develops according to his/her unique genetic make-up. However, some general observations can be made about dental development as follows: 

____________________________ are tolerated when assessing the development of the primary dentition than are considered normal in development of the permanent dentition



individual variations in timing and sequence of tooth eruption in the primary dentition are _______________ because often they are not repeated in development of the permanent teeth and therefore have no lasting consequences



larger variations in development are tolerated in the primary dentition because it is desirable to keep treatment interventions for a very young child to the _______ required



boys tend to develop dentally at a __________________________ than girls



mandibular teeth erupt _____________ their maxillary counterparts. In the primary dentition this may be by a few days or weeks. In the permanent dentition, on average, it is by ________________ months.

Having made those general statements, the dentition chronologies below are suggested as easily remembered guidelines for use in examining children. THE PRIMARY DENTITION The chart below represents a shortened version from most eruption sequences presented in most dental anatomy texts. It is designed to be relatively easy to remember and to provide sufficient information to assess the average child client. You will note that a relatively large age range is considered to be normal when we are considering development of the primary dentition. There is little clinical significance to the timing differences between the eruption of the mandibular teeth and the maxillary teeth during primary dentition development. For this reason we can consider the eruption sequence as relating to all of each type of tooth in the arches because we are not particularly concerned about the relationship of the timing of mandibular tooth eruption to the timing of its maxillary counterpart.

Advanced Dental Anatomy, Course Supplement. C. Thom and D. Dufresne

3

BASIC ERUPTION SEQUENCE Tooth Type (Order of Appearance)

Approx. Age of Eruption (Months)

Approx. Age of Exfoliation (Years)

central incisor (1) lateral incisor (2) canine (cuspid) (4) first molar (3) second molar (5) Reference: J. Nield-Gehrig & D. Willman (2013), Patient assessment Tutorials, Third Edition, pp 548 - 549

Note: THE PERMANENT DENTITION In the development of the permanent dentition, deviations from the normal eruption sequence and timing have _____________________________. Permanent tooth eruption marks the last chance for development of a functional dentition for the individual’s lifetime. Mistakes that occur in the exfoliation of primary teeth and the eruption of the permanent teeth have lasting results. There are significant differences in the sequences of eruption between the maxillary and mandibular teeth. That is why, in the chart below, each arch is considered separately. You will remember that, on average, in the permanent dentition mandibular teeth erupt ____________________________ before their maxillary counterpart. In order to simplify the chart for memorisation, the ages of eruption have been rounded up to the next highest year. This strategy does not have a serious impact on the usefulness of the information. Remember, you should have the detailed information of a full dental development chart from a text available at your workplace should you need to make finer assessments for individual cases.

Advanced Dental Anatomy, Course Supplement. C. Thom and D. Dufresne

4

BASIC ERUPTION SEQUENCE MAXILLA AGE (in years)

ORDER

MANDIBLE TOOTH

ORDER

central incisor lateral incisor canine first premolar second premolar first molar second molar third molar

Advanced Dental Anatomy, Course Supplement. C. Thom and D. Dufresne

AGE (in years)...