4Arrangement of TeethPrimary Dentition refers to the twenty deciduous teeth, also called “baby teeth”.Secondary Dentition refers to the thirty-two permanent teeth.The dentition is divided into two arches: upper and lower, also known as maxillary and mandibular arches.Each arch is arranged into a right and a left half. Thus there are four quadrants.The line that divides left and right quadrants is the median line or midline of the face.
6Arrangement of TeethThe permanent teeth that replace the deciduous teeth are called succedaneous teeth.Permanent molars are nonsuccedaneous teeth.The permanent premolars replace the deciduous molars.A mixed dentition is composed of some permanent and some deciduous teeth.
8Palmer Notation System Each of the four quadrants is given his own prefix symbol.The number or letter assigned to the tooth depends on its position relative to the midline.The first number indicates the quadrant and whether the tooth is permanent or deciduous.
9Palmer Notation System Second premolarFirst premolarFirst molarSecond molarThird molarCentral incisorLateral incisorMaxillary RightMaxillary LeftMidlineCanine8765432112345678Maxillary- Mandibular dividing line8765432112345678Mandibular RightMandibular LeftPermanent Teeth
10Palmer Notation System Second molarFirst molarCentral incisorLateral incisorCanineMaxillary RightMaxillary LeftEDCBAABCDEEDCBAABCDEMandibular RightMandibular LeftPrimary Teeth
11FDI System (Fédération Dentaire Internationale) Each tooth – permanent or deciduous is given a two-digit numberThe second digit indicates the position of the tooth relative to the midlineThe first number indicates the quadrant and whether the tooth is permanent or deciduous
16Development and Form6th week of fetal life deciduous teeth begin to develop from tooth germs4th month of fetal life permanent teeth begin to develop4-5th month of fetal life primary teeth begin to calcify. This process continues until ~3-4th year after birth, when the roots of deciduous teeth are fully formedBirth permanent teeth begin to calcify and continue until ~25th year (third molar roots)
17Developmental LobesEach tooth begins to develop from 4 or more growth centers or developmental lobesAnterior teeth and maxillary premolars develop from 4 lobes – 3 labials and lingual. As the lobes grow, they coalesce. The lines formed by the fusion are called developmental groovesMamelons are the incisal ridges of the three labial developmental lobes of anterior teethThe lingual lobe makes up the cingulum of the tooth
19Lobes and CuspsMaxillary premolars – 3 facial lobes/1 lingual lobe 3 facial high buccal cusp lingual large lingual cuspMandibular 1st premolar same as above except smaller lingual cuspMandibular 2nd premolara) 2 cusp variety same as mand. 1st premolarb) 3 cusp variety buccal lobes-2 lingual lobes leading to two lingual cusps (ML and DL)
21Lobes and Cusps Max. 1st molar: Max 2nd molar: Max 3rd molar: two major facial lobes (MB,DB)one major lingual lobe (ML)one minor lingual lobe (DL)one rudimentary lobe (Carabelli)Max 2nd molar:4 lobes; usually does not have cusp of carabelliMax 3rd molar:3-4 lobes
23Lobes and Cusps Mand. 1st molar: 5 lobes 4 major cusps (MB, DB, ML, DL)1 minor cusp (D)Mand 2ed molar: 4 lobes, cusps.Mand. 3rd molar: 4 lobes, cusps.The most unpredictable teeth in size and shape. They are also the most likely to be missing.
25Eruption General rules: Mandibular teeth usually precede maxillary (about 1 month).Teeth in both jaws erupt in pairs ( one on the right and one on the left).Teeth usually erupt earlier in girls than in boys.all deciduous teeth usually erupted by 2 3/4 years old.
26Eruption of Deciduous Teeth Central incisors monthsLateral incisors months1st molars monthscanines months2nd molars months
27Eruption of Permanent teeth 1st molar – 1st permanent tooth to erupt. They emerge distal to the deciduous 2nd molars (~6 years old).Mesial drift occursSpaces between deciduous teeth are closed.If deciduous tooth is lost prematurely, the permanent molar moves into the available space a may keep a premolar or canine from erupting.
28Eruption of Permanent Teeth Exfoliation: process by which the roots of a baby tooth are resorbed and dissolved until the tooth falls out.As a permanent tooth erupts, the pressure activates osteoclasts which in turn destroy the roots of deciduous teeth.Permanent teeth erupt lingually to the deciduous teeth.
29Most Common Pattern of Eruption Mand 1st molars – Max 1st molarsMand central incisors – Max central incisorsMand lateral – Max lateralMand canines – Mand 1st PM- Max 1st PMMax 2nd PM – Mand 2nd PM - Max CanineMand 2nd molars – Max 2nd molarsMand 3rd molars – Max 3rd molars
30Pattern of Eruption Note: 1. Max canines usually do not erupt until premolars have erupted.2. Mand canines and 1st Premolars often erupt simultaneously.3. Max 2nd premolars often erupt before the mandibular counterparts.
31Pattern of Eruption 3rd molars: Do not appear until 17 years of age or laterMost likely to be impacted(Mandibular > Maxillary)Most common teeth to be congenitally missing
32Pattern of EruptionAs teeth erupt and meet their antagonist on the opposing arch, they form the occlusal plane.The line of the occlusal surfaces is known as occlusal plane.The curved alignment of the occlusal plane is known as curve of Spee.