problems of eruption

lecture given 10/5/2026

what are the requirements for tooth eruption?

force to move tooth along eruption path- not from pulp tissue growth, root formation, or tissue-fluid pressure

removal of bone, teeth, and tissue from eruption path

what is the exact mechanism of tooth eruption?

unknown, but the dental follicle is central to eruption process, interaction with osteoblasts and osteoclasts

what is the sequence of eruption of primary teeth? (lunt and law)

a, b, d, c, e

bcd earlier in maxilla relative to mandible

girls erupt faster than boys

6 mo variation = normal

no signficant left/right differences

when do the central incisor primary teeth erupt?

maxilla- 10 mo

mandible- 8mo

when do the lateral incisor primary teeth erupt?

maxilla- 11mo

mandible- 13mo

when do the canine primary teeth erupt?

maxilla- 19 mo

mandible- 20 mo

when do the 1st molar primary teeth erupt?

maxilla- 16 mo

mandible- 16 mo

when do the 2nd molar primary teeth erupt?

maxilla- 29 mo

mandible- 27 mo

in infants, the eruption of the mandibular central incisors can range from…

birth to 12-14 mo

radiograph cna help to reassure anxious parent

mixed dentition (age 6)

near simultaneous eruption of 1st perm molars and perm central incisors

mixed dentition (age 8)

eruption of perm lateral incisors

when do the central incisor perm teeth erupt?

maxilla- 7-8

mandible- 6-7

when do the lateral incisor perm teeth erupt?

maxilla- 8-9

mandible- 7-8

when do the canine perm teeth erupt?

maxilla- 11-12

mandible- 9-10

when do the 1st premolar perm teeth erupt?

maxilla- 10-11

mandible- 10-12

when do the 2nd premolar perm teeth erupt?

maxilla- 10-12

mandible- 11-12

when do the 1st molar perm teeth erupt?

maxilla- 6-7

mandible- 6-7

when do the 2nd molar perm teeth erupt?

maxilla- 12-13

mandible- 11-13

when do the 3rd molar perm teeth erupt?

maxilla- 17-21

mandible- 17-21

what is the definition of a mixed dentition?

1 2 c d e 6

what are the common variations in timing of eruption?

wide range of chronologica age at time of eruption btwn individuals

girls are generally ahead of boys

influence of premature loss of primary molars on eruption time of successors

eruption of premolar teeth delayed if primary molar extracted at ______

5 yrs or younger

if primary molar is extracted after age 8, the eruption of _______ is ______

permanent premolar, accelerated

extraction of primary teeth within a year of normal exfoliation will ______ eruption of succadaneous teeth

earlier extraction will tend to _____ eruption of succedaneous teeth

accelerate

delay

variations in the sequence of eruptions require more thorough examination- radiographically you should look for…

supernumerary teeth

congenital absence of a tooth

pathology- odontoma, cyst

hypodontia

usually a single tooth

frequency 2.9%

usually occurs with lateral incisors, second premolars, and 3rd molars

key to diagnosis is to count the teeth!

what conditions are attributed to teething?

fever, diarrhea, convulsions, croup

little scientific evidence to support these associations

most studies support only associations with local factor like finger sucking, rubbing gingiva, and drooling

topical anesthetic (baby orajel) should be used ______

judiciously

eruption cyst (hematoma)

well circumscribed dome shaped fluctuant mass- bluish color, overlying erupting toth

generally asymptomatic

commonly seen in both primary and permanent teeth

excision of lesion only if symptomatic

eruption sequestrum

tiny spicule of nonviable calcified tissue, overlying eruption permanent molar

may be local irritant during eruption of permanent molars

if symptomatic, can be removed under local anesthesia

ectopic eruption

most commonly associated with permanent maxillary first molars

prevalence 3-4%

resorption of distal root of second primary molar is common

spntaneous correction (jumping) occurs occasionally

usually requires treatment

may also occur in presence of overretained primary teeth, supernumerary teeth- following extraction of impeding toth the tooth will usually drift into normal position

ectopic eruption of central incisors (shark teeth)

lingual eruption

very common, occurs in children with OR without adequate arch length

gellin and haley (1982) study on ectopic eruption

monitored 57 teeth in 44 children, excluded severe cases of crowding, average age 6 yr and 4 mo

in all cases- labial migraiton occurred naturally and extraction of corresponding primary incisor was unnecessary, 95% by age 8, 2 mo

they recommend extraction only after 8 yrs, if no root resorption is evident

clinically evaluate in case by case basis

natal teeth

present at birth

seen in 1/2000 births

95% are prematurely erupting, NOT extra teeth

neonatal teeth

erupt within 30 days of birth

neonatal and natal teeth

85% O + P

radiograph to evaluate root development

extract if they represent risk of aspiration

also traumatic tongue lesions- riga fede disease

can cause difficulties with feeding

rige fede disease

sharp incisal edge of neonatal tooth may cause laceration of lingual surface of the tongue

extraction may then be necessary

*inclusion cysts of the newborn

lesions frequently found in the mouths of newborns

can be confused occasionally with neonatal teeth

spontaneously shed within weeks of birth

3 types- epstein’s pearls, dental lamina cysts, bohn nodules

epstein pearls

form along the midpalatine raphe at midline

trapped in epithelial tissue

dental lamina cysts

crests of the maxillary and mandibular dental ridges

originate from remnants of dental lamina

bohn nodules

form along buccal and lingual aspects of dental ridges and on palate away from midline

remnants of mucous gland tissue, histologically distinct from epstein pearls

what are local causes of eruption disturbances?

supernumerary teeth, cyst, odontma, jaw fracture, abnormal tooth germ position, tooth germ deformity, bone deficit from cleft palate, lack of space, dilaceration, ankylosis

what are systemic causes of eruption disturbances?

cleidocranial dysplasia, ectodermal dysplasia, gardner syndrome, down syndrome, apert syndrome

what are other causes of eruption disturbances?

non-syndromic primary failure of eruption

ankylosis

fusion of alveolar bone and cementum and/or dentin

local elimination of PDL

can occur any time during or after eruption

incidence- 1.5-9.9% in primary teeth, 1/10th that in permanent teeth

mandibular twice as likely as maxillary

slight ankylosis

infraocclusion between occlusal table and interproximal contact

moderate ankylosis

infraocclusion within contact area

severe ankylosis

infraocclusion below interproximal contact

etiology of ankylosis

exact cause is unknown

possible causes- local metabolic anomaly, genetic, trauma, deficiency of alveolar bone growth, abnormal pressure on soft tissue

associated with some medical conditions- craniofacial dysostosis, hypothyroidism, hypopituitaryism

higher incidence in primary teeth when successor is absent

possible familial pattern

can occur in children as young as 3, ususally during mixed dentition

what are possible consequences of ankylosis?

if tooth becomes infraoccluded- tilting of adjacent teeth, supraeruption of opposing tooth, lack of alveolar bone development, deviation of midline to affected side

periodontal problems

delayed exfoliation, esp if successor is missing

deflected eruption path of permanent successor

delayed eruption of permanent successor

tipping of adjacent teeth

supraeruption of opposing teeth

complications of surgical extractions

what are the most commonly ankylosed teeth?

primary molars (submerged)

assocation with congenitally missing permanent successors

how should ankylosis be treated?

need to be carefully observed

if infraocclusion worsens, space loss/impaction may result

extraction may occasionally be necessary

primary failure of eruption

diagnosis of exclusion

malfunction of eruption mechanism

cessation of tooth eruption before eruption that is not due to physical barrier, abnormal tooth position, or systemic cause

0.06% incidence, females more affected than males

need to be confirmed w tooth distal to the involved

what are characteristics of primary failure of eruption?

posterior more affected than anterior

1st and 2nd permanent molars most affected

teeth may or may not erupt before submerging

unilateral or bilateral

unerupted teeth usually become ankylosed

teeth distal to first involved tooth also affected

lack of alveolar bone development

ortho treatment leads to ankylosis

same frequency in maxilla and mandible

primary failure of eruption type I

progressive open bite from anterior to posterior

primary failure of eruption type II

distal tooth has greater but inadequate eruption compared to first involved tooth

what is the etiology of primary failure of eruption?

no associated disorder or interference with eruption

abnormal PPDL

genetic inheritance- autosomal dominant (M and F equally affected), mutation PTHR1 gene

PTHR1 gene

GPCR for parathyroid hormone (PTH) and PTHLH

found in dental mesenchyme, alveolar bone, and surface of osteoblasts; PTHLH found in epithelial layer

osteoclasts are stimulated with hormone bound to PTHR1

involved in epithelial-mesenchymal interaction regulation during eruption

PTHR1 inactivation leads to blomstrand osteochrondrodysplasia, a fatal form of dwarfism

eruption disturbance likely from partial deficiency of PTHR1

diagnostic characteristics of ankylosis

metallic sound upon percussion (1/3 of cases)

lack of mobility

infraocclusion

loss of PDL on radiograph (1/3 of cases)

no response to ortho treatment alone

if affected primary tooth removed, successor tooth will erupt

diagnostic characteristics of PFE

diagnosis of exclusion

clinical and radiographic diagnosis

failure to erupt when path is clear

no response to ortho treatment, often worsening condition

no treatment with ankylosis

if no or mild infraocclusion with no tipping of adjacent teeth

in primary teeth, if successor is in proper position

mild infraocclusion should not cause periodontal problems

primary tooth may be delayed in exfoliated by 6 mo

no treatment with PFE

recommended treatment until growth completes

take radiographs and review eruption at recalls- root fully formed, be more concerned its PFE