DEVELOPMENT OF DENTITION 1.PRE-DENTAL PERIOD- birth- 6 months a. Gum pads b. Precociously erupted primary teeth 2. DECIDUOUS DENTITION PERIOD 3. MIXED DENTITION PERIOD 4. PERMANENT DENTITION PERIOD www.indiandentalacademy.com
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1. PRE-DENTAL PERIOD- Birth- 6 months a.GUM PADSThe alveolar processes at the time of birth are known as gum pads
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The gum pads are pink, firm and resilient and are covered by a dense layer of fibrous periosteum. Upper gum pad : Horse shoe shaped Lower gum pad : ‘U’ shaped Develop in 2 parts: a. Labio-buccal portion b. Lingual portion The 2 portions are separated by a groove called DENTAL GROOVE www.indiandentalacademy.com
a. LABIO-BUCCAL PORTIONDifferentiates first and grows more rapidly. Divided into 10 segments by grooves called TRANSVERSE GROOVES. Each segment consist of one developing tooth sac. The transverse groove between canine and 1st deciduous molar is called the LATERAL SULCUS. www.indiandentalacademy.com
b. LINGUAL PORTION
Differentiates later. Remains relatively smooth. The upper and lower gum pads are separated from the palate and the floor of the mouth respectively by a groove called GINGIVAL GROOVE. www.indiandentalacademy.com
RELATIONSHIP OF GUM PADS-
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Upper gum pad is wider and longer than the lower gum pad . Thus when approximated, complete overjet present all around.
Anterior open bite present at rest with contact only in the deciduous 1st molar region. Tongue protrudes anteriorly through this space- helps in suckling Permits eruption of lower incisors without impingement on upper gum pad.
Lateral sulcus of mandibular arch is normally distal to that of maxillary arch. www.indiandentalacademy.com
b. PRECOCIOUSLY ERUPTED PRIMARY TEETH1.NATAL TEETH Teeth that are present at the time of birth are called natal teeth. Usually mandibular incisors. Show familial tendency.
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2.NEO-NATAL TEETHďƒ˜Teeth that erupt during 1st month of age are called neonatal teeth. ďƒ˜Mostly seen in mandibular incisor region and show familial tendency.
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DEVELOPMENT OF PRIMARY DENTITION Initiation of primary tooth buds occurs during 6 weeks of intrauterine life. Primary teeth begin to erupt at about 6 months of age. Eruption of all primary teeth is completed by 24- 30 months of age
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ERUPTION AGE AND SEQUENCE OF DECIDUOUS DENTITION SEQUENCE:
A- B- D- C- E
The mandibular central incisors are the 1st to erupt at around 6-7 months of age. - Timing of tooth eruption is highly variable. - A variation of 3 months from the mean age has been acceptable as normal. www.indiandentalacademy.com
NORMAL FEATURES OF PRIMARY DENTITIONPHYSIOLOGICAL SPACES/ DEVELOPMENTAL SPACES:
Usually seen in deciduous dentition to accommodate the larger permanent teeth in the jaws.
Absence of spacing in deciduous dentition is an indication that crowding of teeth may occur in permanent dentition.
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2. PRIMATE / SIMIAN / ANTHROPOID SPACES Present mesial to deciduous maxillary canine and distal to mandibular canine. Commonly seen in primates. Help in interdigitation of opposing canines. Used for early shift
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3.ALMOST VERTICAL INCLINATION OF INCISORS
4.SHALLOW OVERJET AND OVERBITE
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TERMINAL PLANE RELATIONSHIPThe mesio- distal relation between the distal surfaces of the upper and lower 2nd deciduous molars is called the TERMINAL PLANE
3 TYPES: a. FLUSH TERMINAL PLANE- Distal surfaces of the upper and lower 2nd deciduous molars are in the same vertical plane. - This is regarded as normal relation in deciduous dentition.
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b. MESIAL STEPDistal surface of mandibular deciduous 2nd molar is mesial to the distal surface of maxillary deciduous 2nd molar.
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c. DISTAL STEPDistal surface of mandibular deciduous 2nd molar is more distal than the distal surface of maxillary 2nd molar.
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The primary dentition is usually established by 3 years of age.
Between 3-6 years , the dental arch is relatively stable and very few changes occur in the dentition in this period.
The deciduous dentition period lasts for 6 years of age till the eruption of permanent 1st molars which marks the beginning of the mixed dentition period. www.indiandentalacademy.com
www.indiandentalacademy.com Leader in continuing dental education
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