Primary Dentition Anatomical Differences And Implications Flashcards
How many teeth are their in the primary dentition?
20
Incisors (A, B), canines (C), and molars (D, E)
What would a lower left D be in FDI notation?
74
What would an upper right B be in FDI notation?
52
What tooth is 83 in FDI notation?
Lower right C
What tooth would 36 be in FDI notation?
Lower left 1st permanent molar
What would an upper left second premolar be in FDI notation?
25
What percentage of primary occlusion have flush dental molars?
75% Mandibular E’s are larger than maxillary E’s so the mesio-buccal cusps of maxillary and mandibular E may be in class I relationship with their distal surfaces flush
What percentage of primary occlusion have a distal molar step?
25%
Distal surfaces of maxillary E projects slightly over distal portion of the mandibular E
What facts are there about the occlusion in the primary dentition?
Maxillary arch is larger than the mandibular arch of teeth
Primary teeth are more upright
Mandibular incisors occlude with the palatal surface of maxillary incisors
Anthropoid space- distal to mandibular C, mesial to maxillary C
Spacing between primary teeth disappears around 4-5 years old
Teeth frequently worn
What is the eruption pattern of the primary dentition?
Mandibular teeth erupt first
Symmetrical pattern
Sequence more important than timing
A, B, D, C, E
How many weeks after ovulation does hard tissue begin to form for the mandibular teeth in the primary dentition?
A- 13-16 weeks B- 14-16 weeks C- 16-18 weeks D- 14-17 weeks E- 17-19 weeks
How many weeks after ovulation does hard tissue begin to form in the maxillary teeth in the primary dentition?
A- 13-16 weeks B- 14-16 weeks C- 15-18 weeks D- 14-17 weeks E- 16-23 weeks
How many months after birth is crown formation complete in the mandibular teeth of the primary dentition?
A- 2.5 months B- 3 months C- 8-9 months D- 5-6 months E- 8-11 months
How many months after birth is crown formation complete for the maxillary teeth in the primary dentition?
A- 1.5 months B- 2.5 months C- 9 months D- 6 months E- 11 months
How many months after birth do the mandibular teeth begin to erupt in the primary dentition?
A- 6-10 months B- 10-16 months C- 17-23 months D- 14-18 months E- 23-31 months
How many months after birth do the maxillary teeth begin to erupt in the primary dentition?
A- 8-12 months B- 9-13 months C- 16-22 months D- 13-19 months E- 25-33 months
How many months after birth is root formation complete in the mandibular teeth of the primary dentition?
A- 33 months B- 30 months C- 43 months D- 34 months E- 42 months
How many months after birth is root formation complete in the maxillary teeth of the primary dentition?
A- 33 months B- 33 months C- 43 months D- 37 months E- 47 months
What are some unusual eruption patterns of primary teeth?
Natal teeth- present at birth
Neonatal teeth- present within 30 days
Late eruption- missing teeth
Where are natal/neonatal teeth usually found?
Often lower incisor region
Not usually supernumerary
What is the aetiology of natal/neonatal teeth?
Unknown
Superficial position of tooth germ
Evidence of genetic contribution as seen in syndromes/CLP
What is the clinical appearance of natal/neonatal teeth?
Normal appearance
Crown small, conical and poorly developed with yellowish hypoplastic enamel and dentine
Poor or failure of root development
What are some clinical symptoms and complications of natal/neonatal teeth?
Possible pain, baby refuses to nurse Trauma to mother’s breast Drooling, malaise Mobility of teeth Risk of swallowing or aspiration Sharp edges- ulceration of tongue (Riga Fede ulceration)
How are natal/neonatal teeth managed?
If there are no problems- leave, reassure, observe
Ulceration- smooth sharp edges or extraction
Problems- extraction
What are the differences between the crowns of primary teeth to permanent teeth?
Smaller
Whiter
Thinner enamel and dentine layers
Enamel rods slope occlusal in cervical layer
Cervical area is significantly constricted
What are the differences in the pulp of primary teeth to permanent teeth?
Large pulp horns closer to the outer surface
More tortuous and irregular pulp canals
What are the differences in the roots of the primary teeth compared to the permanent teeth?
Roots flare as they approach the apex
What is the upper mesial distal width of the primary and permanent teeth?
A- 6.5mm, 1- 8.5mm B- 5.0mm, 2- 6.5mm C- 6.5mm, 3- 8.0mm D- 7.0mm, 4- 7.0mm E- 8.5mm, 5- 6.5mm 6- 10mm 7- 9.5mm
What is the lower mesial distal width of the primary and permanent teeth?
A- 4.0mm, 1- 5.5mm B- 4.5mm, 2- 6.0mm C- 5.5mm, 3- 7.0mm D- 8.0mm, 4- 7.0mm E- 9.5mm, 5- 7.0mm 6- 11mm 7- 10.5mm
What are the crowns of primary incisors like compared to permanent incisors?
Shorter
Marked constriction at cervical margin
Rarely have mamellons
What are the roots of primary incisors like compared to permanent incisors?
Narrower mesiodistally than permanent incisors
What are the differences in the primary canines compared to the secondary canines?
Large crown Bulge at cervical constriction Symmetrical cone shape, or mesial slope (upper) Distal slope longer than mesial (lower) Cusp tip wears rapidly
What are the differences in the primary molar teeth compared to the permanent molars?
Marked cervical constrictions
Buccal bulge
Upper D has 4 cusps (2 larger mesial, 2 smaller buccal)
Lower D has 4 cusps (2 larger buccal, 2 smaller lingual)
E’s have similar fissure/cusp pattern to 6’s
But they have narrower occlusal tables, broad contact points, roots are long, slender and narrow mesio-distally, roots are divergent
Thin, uniform layer of enamel
Thin layer of dentine
What is the difference in the contact points of primary molars compared to permanent molars?
Point contact in permanent dentition
Broad contact points in primary dentition
Early diagnosis of inter proximal caries may be difficult
What is the difference in occlusion of the primary molars compared to the permanent molars?
Incisor relationship more edge to edge
Distal surfaces of upper and lower E’s are in the same vertical plane, upper E’s are longer than lower E’s
What is the difference in the pulp of primary molars compared to permanent molars?
Higher pulp horns in primary
Floor thinner and transversed by feeder vessels
Large pulp follows external contours
Large mesiobuccal pulp horn
What is the difference in the roots of primary molars compared to permanent molars?
Smaller roots
Roots more splayed
What is the innervation of deciduous teeth?
The pattern of innervation shows some similarities to the permanent dentition
Nerves pass from the root to the coronal area where they branch
The profuse news of nerve branching and its proximity to the odontoblast layer are most evident in the pulp horns
There is a high density of dentinal innervation in the cervical region
Do deciduous teeth feel pain?
Yes
The clinical impression of lesser sensitivity to invasive procedures is not explained by the innervation of deciduous teeth
Local anaesthetic is advocated in the restoration of all but minimal cavities of the primary dentition
What are the implications in treatment of a class II cavity?
Decay spreads bucco-lingually Wide, narrow class II prep, poor retention, high failure rate Stainless steel crown required in wide class II cavities
What are the implications for a class I restoration?
Avoid damage to the pulp horn
What is the clinical significance of shorter, narrower crowns with thin enamel/dentine in primary teeth?
Limited room for cavity preps and materials
Miniature hand pieces, short sank burs
What is the clinical significance of the broad contact points in the primary dentition?
Difficult to detect caries
Radiographs needed
Difficult to restore contacts
Large box needed
What is the clinical significance of the cervical constriction of crowns of the primary dentition?
Enamel at floor of box not undermined
What is the clinical significance of the angulation of the enamel prisms at the cervical margin of the crowns of the primary dentition?
Cavity prep should slope occlusally
What is the clinical significance of the buccal bulge of the crowns in the primary dentition?
Retention of SSC- maintain buccal bulge
What is the clinical significance of the narrower occlusal area of the crowns of the primary dentition?
Difficult to place matrix bands
What is the clinical significance of the large pulp in the primary dentition?
Limited room for cavity prep
What is the clinical significance of the pulp horn being close to the surface of the primary dentition?
Exposure easy
What is the clinical significance of the thin floor of the pulp chamber in the primary dentition?
Perforations easy
What is the clinical significance of the narrow mesio-distal root, long roots and flared roots in the primary dentition?
Root canal treatment (pulpectomy) difficult
