Ch 2 Dev't & Eruption of Teeth Prelim review Flashcards
So that surgical intervention doesn't harm normal growth and the relationship between dental age and the effects of disease and enviormental risks.
Dentists sees not only clinical crowns but also:
- number
- shape
- size
- position
- coloration
- angulations of teeth
- outlines of roots
- occlusal contacts
- esthetics
- evidence of function and parafunction
- phonetics
Foundation of diagnosis:
-form of tooth related:
- to accept patient’s concern that a cosmetic problem is present and needs correction, requires dentist to transform patient’s idea of esthetics into reality by ortho and cosmetic restorative dentistry.
- position and angulation in arch.
- appreciation for esthetics of tooth form and coloration is a requirment
Variability
- Know normal morphology and morphological variability
- variety in sequences of eruption depend on population sampled.
- Enamel hypoplasia
- hypocalcification
- all quantitative defects of enamel thickness
- opacities are qualitative defects
- chronologies and location of defect determines when,how,and cause.
Sequence of emergence of primary teeth
CI, LI, 1M, C, 2M
Emergence through alveolar crest
-when approx. 2/3 root is formed
Emergence through cavity
-when approx. 3/4 root is formed
Neuromuscular Dev’t-Primary Dentition
- completed by 30 mo
- increased intercanine width
- ^size in both jaws in sagittal
- ^vertical direction of facial skeleton
- splanchno remains small
- @ age 8, width mandible = width neurocran.
- Dent arch complete, occlusion is functional
Transitional (mixed) dentition
*crown must complete 1st before erupt
-1st begins w/ emerg/erupt of Man 1permM and ends w/ loss of last primary tooth = 11-12 years
Permanent dentition
- 32 teeth, completed 18-25 years
- follicles of developing incisors and canine are lingual to deciduous roots
- developing premolars are within bifurication of primary molar roots
- mandibular permanent grows faster > max perm
Succedaneous
-Permanent incisors, canines, and premolars
size of teeth
- genetically determined, racial differences
- gender-sized dimorphism
Dental pulp
- connective tissues organ containing a # of structures like arteries, veins, lymphatic sys, and nerves
- to form dentin of tooth
- bcomes smaller as tooth is completed
Types of junctions
- enamel over-lapping cementum
- end-to-end approximating junction
- absence of connecting enamel and cementum, so that dentin is external part of root.
- over-lapping of enamel by cementum
Probing
- to determine level of periodontal support, position of gingival margin, and attachment of CEJ
- to probe level of attachment of fibers to tooth in presence of periodontal diseases.
- location and nature of CEJ have clinical sig, not just morphology
- should be able to envision CEJ of each tooth
Dental age assessment
- based on which teeth have erupted and
- the number of teeth at each chronological age
- the amount of resorption of the roots of primary teeth
- stages of the formation of crown and roots
- dev’t of permanent teeth
- can reflect assessment of physiological age comparable to age based on skeletal dev’t, weight, or height
Types of chronologies
-age of attainment: tooth emergence. to avoid damage to developing teeth during treatment.
- age prediction: based on being in a stage
- age in a stage of dev’t. used for assessing unknown ages of patients and for forensic and archeological app.
-maturity assessment: based on mean stage for age, where stages, rather than, subject ages, are averaged. age is known.
Estimating time of Enamel Hypoplasia
ADF = ACF - (years of formation/crown height x distance of defect from CEJ)
- age at which the formation of the enamel hypoplasia occurred
- age at which crown is completedi
Rule of “six” in dental dev’t
- 6 weeks in utero: Onset of dental dev’t
- 6 months old: emergence of the first primary tooth
- 6 years old: emergence of the first permanent tooth
Stages of tooth formation
- beginning calcification
- crown completion
- root completion
- Nolla-11 stages
- Gleiser and Hunt-14 stages
- Resorption:
- Eruption:
- gradual physiologic root destruction by the underlying erupting permanent tooth
- continuous tooth movement from the dental bud to occlusal contact
Rule of “fours” for permanent tooth dev’t (3rd Molars not included)
- at birth:
- at 4 years of age
- at 8 years
- at 12 years
- at 16 years
- four 1st molars have initiated calcification
- all crowns have initiated calcification
- all crowns are completed
- all crowns emerge
- all roots are complete
Sequence of Eruption for Permanent
*mand tend to erupt before max
- man M
- man CI/LI
- max central
- max lateral
- first premolar
- man canine
- second premolar
- max canine
- second molars
- third molars
Sequence of Eruption of Primary
- CI
- LI
- First Molar
- Canine
- Second Molar
systemic fluoride
Crowns take a few years to form once calcification has begun, therefore its impt to take through age 12 to protect all teeth.
Points to remember
- mand > max
- tooth erupts when its root is about half-formed
- the roots of primary teeth will complete about 1.5 years after eruption
- roots of permanent teeth will complete about 2.5 years after eruption
Clinical considerations:
- normal crown vs pathological crown
- roots
- Occlusal contacts
- gingiva
- size, shape, position, number, color
- outline
- function, parafunction, and phonetics
- appearance
Malformations
- form ex: screw-driver shaped max incisors
- color
- arrangement
- structure of teeth ex: enamel hypoplasia
