DENTAL ANATOMY 1st Semester 2008/2009 Academic Year Department of Stomatology School of Stomatology Wenzhou Medical College

Primary (and Mixed) Dentition Kevin Yang Li Hong-qing

SECTION 1 Background Info. Objectives Dental formulae Functions of primary dentition

A definitions Deciduous teeth Primary teeth Nicknames Deciduous: fall off Primary teeth Nicknames Milk teeth Temporary teeth

B Dental formulae Primary teeth Permanent teeth I2/2+C1/1+M2/2=5/5 I2/2+C1/1+P2/2+M3/3=8/8

Teeth numbering A to T

1D to 20D

C functions Mastication of food

Support the cheeks and lips

Speech formulation

Maintaining the space and arch continuity

SECTION 2 Developmental Data Objective Time ranges for primary and secondary tooth eruption Time ranges crown and root formation for primary and secondary teeth Oder of eruption of primary and secondary teeth

A important times for tooth emergence No teeth Birth 6(or8) months old: Primary dentition only 6(or8) months-2(or21/2)old: 2(or21/2)-6(or53/4)years old:

Mixed dentition Adult dentition only 6(or53/4)years old: 6-9years old:

B crown and root development General development primary teeth: Lobes- crown calcifications- root formation, tooth eruption process- resorption- exfoliation Succedaneous teeth: Lobes- crown calcifications- root formation, tooth eruption process

Average primary crown calcification time? When does root formation begin? When does tooth start to erupt? How long does the eruption process last? Order of emergence of primary teeth? When do the primary tooth roots are completed? What’s Mixed dentition? Age of mixed dentition? Age of crown formation of 2nd teeth? Oder of emergence for 2nd teeth? 1st and last emergence tooth of 2nd teeth?

SECTION 3 Dentition traits of all primary teeth Specimens The best: in kids mouth Or: plastic model

General traits compared to secondary teeth Smaller in size Whiter Marked constriction at cervix Relative longer roots Large pulp cavity, thin enamel and dentin layer Less mineralized More consistent shape

Traits of all primary anterior teeth Cervical ridges on facial surfaces are prominent Lingual cingula are prominent Labial surfaces are smooth

Root traits of primary teeth Long to the crown Narrow mesiodistally Roots bend labially

Traits of primary posterior teeth Prominent cervical ridge Narrow occlusal table

Buccal view: wide mesiodistally Shallow occlusal anotomy

Few grooves or depressions Primary second molar larger than primary first molar

Root traits of primary teeth Root furcation near the crown, little or no trunk Roots are thin or slender Root number and relative size

SECTION 4 Class and Type Traits Primary incisor traits Primary canine traits Primary molar traits

SECTION 5 pulp cavity Anterior teeth Posterior teeth (molars) Large pulp cavity Slight projection Posterior teeth (molars) Chamber Less elongated vertically Pulp chamber in root crown Long, narrow pulp horns