CHRONOLOGY OF PRIMARY AND PERMANENT

DENTITION.

M. BHARATH REDDY

OBJECTIVES

• INTRODUCTION• DEFINITION• TYPES• CHRONOLOGY OF PRIMARY DENTITION• MIXED DENTITION PERIOD• CHRONOLOGY OF PERMANENT

DENTITION• SIGNIFICANCE OF CHRONOLOGY

INTRODUCTION

• Chronology of dentition is based upon data of Logan and kronfeld reported in 1933.

• Careful review was done by • masseler and shour in 1941.• morrees and fanning and hunt in 1963• kraus and jordan in 1965• Nystrom in 1977

DEFINITION

• Chronos-time• Logos-study• Chronology is defined as “a study

which deals with the timings of various stages of tooth development. starting with the initiation of the first dental tissue laid down to the emergence of tooth in the oral cavity and its completion of calcification”.

Age of prediction Maturity assesment

Age of attainment

Types of chronologies

• AGE OF ATTAINMENT:

1. IT IS BASED UPON TOOTH EMERGENCE

2. IT IS USED CLINICALLY TO AVOID DAMAGE TO DEVELOPING TOOTH DURING TREATMENT

• AGE OF PREDICTION:

1. IT IS BASED ON THE AVERAGE AGE OF THE SUBJECTS IN A STAGE OF DEVELOPMENT

2. AGE PREDICTION ARE USED FOR ASSESSING UNKNOWN AGE OF PATIENTS AND FORENSIC ARCHEALOGICAL APPEARANCE

MATURITY ASSESSMENT:

1. HERE THE STAGES ARE AVERAGED RATHER THEN SUBJECT AGES.

2. SUCH SCALES ARE USEFUL WHEN MATURITY IS ASSESSED OF KNOWN AGE

CHRONOLOGY OF PRIMARY DENTITION

SEQUENCE OF EMERGENCE OF PRIMARY TEETH

• THE PREDOMINAT SEQUENCE OF ERUPTION OF PRIMARY TEETH IN THE INDIVIDUAL JAW IS

• (A) CENTRAL INCISOR• (B) LATERAL INCISOR• (D) FIRST MOLAR• (C) CANINE• (E) SECOND MOLAR

SEQUENCE OF ERUPTION

AB D C E A B D CE

MIXED DENTITION PERIOD• THE FIRST MIXED DENTITION BEGINS

WITH THE EMERGENCE AND ERUPTION OF MANDIBULAR FIRST PERMANENT MOLARS

• IT ENDS WITH THE LOSS OF THE LAST PRIMARY TOOTH WHICH USUALLY OCCURS AT 11-12YRS

PERMANENT DENTITION IS COMPLETED FROM 18 TO 25 YRS Of AGE IF 3RD MOLAR INCLUDED

CHRONOLOGY OF PERMANENT DENTITION

Importance of chronology

• TO AVOID TREATMENT THAT CAN DAMAGE DEVELOPING TEETH

• TO ASSESS UNKNOWN AGE OF THE PATIENT

• TO ASSESS GROWTH

• TO AVOID MALFORMATIONS OF THE TEETH

REFERENCES

• WHEELER’S

• SHOBHA TANDON

• INTERNET