Missing laterals and delayed eruption

Question 1

What is the prevalence of missing laterals in Caucasian population?

Answer 1

1-2% but 20% of all missing teeth

Question 2

What are the most common missing teeth in order?

Answer 2

Lower 2nd premolar 40%
Upper lateral incisor 24%
Upper 2nd premolar 20%

Question 3

What conditions are linked with missing laterals?

Answer 3

CLP
Down’s syndrome
Ectodermal dysplasia
Early irradiation of tooth germs

Question 4

When should missing laterals be suspected?

Answer 4

Suspect missing laterals if not erupted by age of 9 or within 6months of contralateral

Question 5

What are the management options for missing laterals?

Answer 5

1. Accept situation
2. Restorative camouflage with composite bonding/veneers
3. Orthodontic space closure and substitution of the canine for missing lateral +/- restorative treatment (not for class 3)
4. Orthodontic space opening for prosthetic replacement (implants for over 18s only)

Question 6

What aspects in a missing lateral case would allow for single tooth implant?

Answer 6

Pt over 18 or will ankylosis and infra occlude
Must have parallelism of roots
Enough space for implant - minimum 6.5mm
Good OH and bone levels

Question 7

What is delayed eruption?

Answer 7

Tooth fails to erupt within 6months of its contralateral or if there is significant deviation from normal sequence of eruption

Question 8

What are the main causes of delayed eruption of teeth?

Answer 8

Absence
Crowding 
Delayed exfoliation (trauma related)
Supernumeraries 
Odontome 
Pathology - cysts 
Dilaceration - trauma result 
Abnormal position of crypt - ectopic canine 
Retained primary teeth 
Impaction 
Premature loss

Question 9

What conditions are linked with delayed eruption of teeth?

Answer 9

Cleidocranial dysostosis (delayed eruption and multiple supernumeraries) 
Hereditary gingival fibromatosis 
Down’s syndrome
CLP
Hypothyroidism/Hypoparathyroidism
Gardeners syndrome

Question 10

What is the rates of supernumerary teeth in permanent and primary teeth?

Answer 10

2% permanent

1% primary

Question 11

What are the types of supernumeraries?

Answer 11

Conical (mesiodens)

• conical or peg shaped
• common between upper centrals
• often cause median diastema

Tuberculate (barrel shaped)
-associated with failure of eruption

Odontome

• complex and compound types
• may resemble collection of tooth tissue

Question 12

What causes infra occlusion?

Answer 12

Generally caused by ankylosis and should suspect missing teeth if primary tooth is retained.
Common of 2nd primary molar if premolar is missing

Question 13

What percentage of population has reported infra occluded teeth?

Answer 13

55%

- 8.3% are significant cases

Question 14

What are the options for infra occluded teeth?

Answer 14

1. Early extraction if wishing to preserve vertical bone height for implants
2. Retain tooth - build up with composite to maintain height and avoid over eruption of opposing and tipping of adjacent teeth

Question 15

What is the aetiology of ectopic canines in population and position of these teeth?

Answer 15

1.5% of population
10% are bilateral
37% have palatal displaced canines

Question 16

When should ectopic canines be palpable in sulcus?

Answer 16

Should be palpable by age 10/11. If not radiographs are required:
PA and upper occlusal or OPT and PA parallax technique to know position of tooth.

Question 17

What are the treatment options for ectopic canines?

Answer 17

1. Extraction of the C
2. Surgical exposure and orthodontic alignment/gold chain
3. Surgical removal of impacted canine
4. Transplantation of another tooth
5. No active Tx - leave and observe

Question 18

What is the main consequence of a conical supernumerary tooth?

Answer 18

Tends not to prevent eruption but may displace /rotate adjacent teeth.