Peds- NBDE Part II UPDATED ACTUAL Questions and
CORRECT Answers
Odontogenesis
Initiation 6 weeks in utero
-Thickening
• Oral epithelium= outer layer, derived from ectoderm
• Dental lamina= first evidence of forming, budding teeth, derived from ectoderm
• Ectomesenchyme= signals overlying oral epithelium to proliferate into dental
lamina, derived from ectoderm- neural crest
Defects= congenitally missing, supernumerary
Bud Stage 8 weeks in utero
• Dental placode= proliferating bud
– All primary teeth and permanent molars arise from dental lamina
– Permanent incisors, canines, and premolars arise from their primary
predecessor- a piece of the primary bud comes off
• Condensing mesenchyme
Defects= congenitally missing, supernumerary
Cap Stage 9 weeks in utero
Also known as proliferation
• Enamel organ (enamel) – OEE= outer cell layer (outer enamel epithelium)
– IEE= inner cell layer– Stellate reticulum= between layers – Enamel knot (cusp
tips)
• Dental papilla (dentin and pulp) • Dental follicle= surrounding sac
Defects= cyst, odontoma, gemination, fusion, dens in dente
,Bell Stage: 11 weeks in utero
2 things happen:
1. Histodifferentiation
• Transformation into distinct cell types – IEE-> ameloblasts– Dental papilla->
odontoblasts
-Defects= amelogenesis imperfecta, dentinogenesis imperfecta
2.Morphodifferentiation
• Shape and size of eventual crown is determined during this process
Defects= size and shape abnormalities like peg laterals and macrodontia
Apposition 14 weeks in utero
-defects • 1st Odontoblasts deposit dentin matrix (collagen) which signals -->
• Ameloblasts deposit enamel matrix (amelogenin) which signals -->
• Cervical loop= where IEE and OEE join, elongates and grows down and forms --
>
– Hertwig’s epithelial root sheath (HERS), stimulates odontoblasts to form
radicular dentin (dentin that is part of the root), HERS eventually disintegrates and
leaves behind -->
– Epithelial rests of Malassez (vestigial structure in PDL)
• Stellate reticulum pops and join IEE + OEE = REE- reduced enamel epithelium (
forms junctional epithelium)
-what remains of dental papilla becomes the pulp
Defects= enamel hypoplasia (Turner's hypoplasia), enamel pearls, concrescence
Maturation 14+ weeks in utero
-Longest stage of tooth development
-Deposition of enamel and dentin
-Calcification begins at cusp tips/incisal edges and proceeds cervically
-Takes 2 years to complete for primary tooth crown
-Takes 4-5 years to complete for permanent tooth crown (not including the root)
Defects= enamel hypomineralization, fluorosis (enamel), tetracycline staining
(dentin layer)
-most common defects bc occurs from 14 weeks in utero - ~16 years old, the later
defects come the less detrimental
TOOTH GERM summary -differentiates to • Enamel organ
–Ameloblasts-> enamel
• Dental papilla
–Odontoblasts -> dentin
– Central cells-> pulp
• Dental follicle
– Cementoblasts -> cementum
– Osteoblasts-> alveolar bone
– Fibroblasts-> PDL
, Calcification Dates
-Primary teeth
Calcification Dates
-Permanent teeth
Primary eruption sequence 6, 16, 26
nxi
Permanent eruption sequence MAIN
2-3 rule= teeth erupt with 2/3 of their root developed, then after that point the
root takes another 2-3 years to complete development
Anomalies of Number • Supernumerary
• Congenital absence
(during initiation or bud stage)
Supernumerary Teeth • 3% of population
• Most common is mesiodens (b/w 8+9 usually palatally)
• May block normal eruption of permanent teeth
Congenitally Missing Teeth (After 3rd molars) Mandibular second premolars > maxillary laterals > maxillary
second premolars- OS quizle wrong!!
– Second premolar-> close spaces with extraction treatment to make symmetrical
– Lateral-> canine substitution or prosthetic replacement
Primary maxillary lateral incisor is most common congenitally missing primary
tooth
-Most commonly ankylosed tooth is Primary E (mandibular 2nd molar)-
mandibular 2nd PM replaces could be why it is most likely missing!
Anomalies of Size • Microdontia
• Macrodontia
• Fusion
• Gemination
(Cap stage)
CORRECT Answers
Odontogenesis
Initiation 6 weeks in utero
-Thickening
• Oral epithelium= outer layer, derived from ectoderm
• Dental lamina= first evidence of forming, budding teeth, derived from ectoderm
• Ectomesenchyme= signals overlying oral epithelium to proliferate into dental
lamina, derived from ectoderm- neural crest
Defects= congenitally missing, supernumerary
Bud Stage 8 weeks in utero
• Dental placode= proliferating bud
– All primary teeth and permanent molars arise from dental lamina
– Permanent incisors, canines, and premolars arise from their primary
predecessor- a piece of the primary bud comes off
• Condensing mesenchyme
Defects= congenitally missing, supernumerary
Cap Stage 9 weeks in utero
Also known as proliferation
• Enamel organ (enamel) – OEE= outer cell layer (outer enamel epithelium)
– IEE= inner cell layer– Stellate reticulum= between layers – Enamel knot (cusp
tips)
• Dental papilla (dentin and pulp) • Dental follicle= surrounding sac
Defects= cyst, odontoma, gemination, fusion, dens in dente
,Bell Stage: 11 weeks in utero
2 things happen:
1. Histodifferentiation
• Transformation into distinct cell types – IEE-> ameloblasts– Dental papilla->
odontoblasts
-Defects= amelogenesis imperfecta, dentinogenesis imperfecta
2.Morphodifferentiation
• Shape and size of eventual crown is determined during this process
Defects= size and shape abnormalities like peg laterals and macrodontia
Apposition 14 weeks in utero
-defects • 1st Odontoblasts deposit dentin matrix (collagen) which signals -->
• Ameloblasts deposit enamel matrix (amelogenin) which signals -->
• Cervical loop= where IEE and OEE join, elongates and grows down and forms --
>
– Hertwig’s epithelial root sheath (HERS), stimulates odontoblasts to form
radicular dentin (dentin that is part of the root), HERS eventually disintegrates and
leaves behind -->
– Epithelial rests of Malassez (vestigial structure in PDL)
• Stellate reticulum pops and join IEE + OEE = REE- reduced enamel epithelium (
forms junctional epithelium)
-what remains of dental papilla becomes the pulp
Defects= enamel hypoplasia (Turner's hypoplasia), enamel pearls, concrescence
Maturation 14+ weeks in utero
-Longest stage of tooth development
-Deposition of enamel and dentin
-Calcification begins at cusp tips/incisal edges and proceeds cervically
-Takes 2 years to complete for primary tooth crown
-Takes 4-5 years to complete for permanent tooth crown (not including the root)
Defects= enamel hypomineralization, fluorosis (enamel), tetracycline staining
(dentin layer)
-most common defects bc occurs from 14 weeks in utero - ~16 years old, the later
defects come the less detrimental
TOOTH GERM summary -differentiates to • Enamel organ
–Ameloblasts-> enamel
• Dental papilla
–Odontoblasts -> dentin
– Central cells-> pulp
• Dental follicle
– Cementoblasts -> cementum
– Osteoblasts-> alveolar bone
– Fibroblasts-> PDL
, Calcification Dates
-Primary teeth
Calcification Dates
-Permanent teeth
Primary eruption sequence 6, 16, 26
nxi
Permanent eruption sequence MAIN
2-3 rule= teeth erupt with 2/3 of their root developed, then after that point the
root takes another 2-3 years to complete development
Anomalies of Number • Supernumerary
• Congenital absence
(during initiation or bud stage)
Supernumerary Teeth • 3% of population
• Most common is mesiodens (b/w 8+9 usually palatally)
• May block normal eruption of permanent teeth
Congenitally Missing Teeth (After 3rd molars) Mandibular second premolars > maxillary laterals > maxillary
second premolars- OS quizle wrong!!
– Second premolar-> close spaces with extraction treatment to make symmetrical
– Lateral-> canine substitution or prosthetic replacement
Primary maxillary lateral incisor is most common congenitally missing primary
tooth
-Most commonly ankylosed tooth is Primary E (mandibular 2nd molar)-
mandibular 2nd PM replaces could be why it is most likely missing!
Anomalies of Size • Microdontia
• Macrodontia
• Fusion
• Gemination
(Cap stage)
