Lecture 1 Flashcards
Less than 6 congenitally missing teeth:
hypodontia
More than 6 congenitally missing teeth:
oligodontia
Abscence of all teeth:
anodontia
Extra teeth (supernumerary teeth):
hyperdontia
What 7 things are known to result in congenitally missing teeth?
- ectodermal dysplasia
- hypothyroidism
- down syndrome
- cleft palate
- genetics
- radiation
- random
Group of syndromes causing missing or peg shaped teeth, thin, sparse hair, and absence of sweat glands:
ectodermal dysplasia
Cleft palates occur in _____ briths
600-800
What is the cause of congenitally missing teeth?
due to disturbances during the initial stages of tooth formation (initiation & proliferation)
What specific stages of tooth formation are disturbed resulting in congenitally missing teeth?
initiation & proliferation
T/F: If a primary tooth is missing, there is a chance the permanent successor will be present
false- since primary tooth buds give rise to permanent tooth buds, it is not possible to be a successor if the primary tooth bud is missing
Is it possible to have missing permanent teeth even when there was a primary tooth?
yes
What is the INCIDENCE of hypodontia of in the general population?
General population: 2-10% (excluding 3rd molars)
What is the incidence of congenitally missing primary teeth?
0.1-0.4%
What is the incidence of congenitally missing 3rd molars?
20-25%
What sex is hypodontia more common in?
females (3:2 ratio)
T/F: Hypodontia commonly runs in families
true
What is the general rule to hypodontia?
As a general rule, if only one or a few teeth are missing, the absent tooth will be the most DISTAL tooth of any given type
Missing teeth can be inherited as part of a syndrome or a:
polygenic multifactorial model of etiology
What genes are etiologic factor in hypodontia?
MSX1, PAX9, AXIN2
List 2 medically induced etiologies of hypodontia:
- cytotoxic drugs
- radiotherapy
T/F: The etiology of hypodontia can be random
true
What are the most commonly missing permanent teeth?
mandibular 2nd premolars
maxillary 2nd premolars
maxillary lateral incisors
maxillary second molars
Are maxillary or mandibular 2nd premolars missing more often?
mandibular 2nd premolars
What are the REPLACEMENT options for hypodontia?
- prosthetically
- transplantation
- implant
What are the treatment options for hypodontia?
- replacement
- extraction of primary tooth to allow tooth drift
- extraction followed by ortho
- maintain tooth or teeth (occlusal problems to be expected)
What must be considered if replacement via implant is the chose treatment for hypodontia?
retain primary tooth until close to time of implant placement to ensure good bone
What do you need for proper canine substitution?
- similar color to central incisor
- narrow width at CEJ
- relatively flat labial surface
- narrow mid-crown BL width
- enameloplasty
What is the order of canine enameloplast?
- cusp tip
- mesial and distal (often underperformed)
- labial ridge
- add mesial composite
- line angles
Extra, supernumerary teeth have great potential to:
disrupt normal occlusion
What is indicated with supernumerary teeth?
early intervention to remove them as indicated
Is the incidence of HYPERdontia higher or lower than HYPOdontia?
Lower
What is the incidence of HYPERdontia in primary dentition, then permanent dentition?
primary = 0.5%
permanent= 1.0%
If hyperdontia occurs, what percent of the time does it occur in the maxilla?
85%
T/F: Hyperdontia occurs in the upper jaw/ pre-maxilla area 85% of the time
true
Where are mesiodens commonly located?
maxillary midline
Do mesiodens often exist singularly or in combination?
They are most often singular, however CAN also exist in combination
Can mesiodens deflect teeth?
yes
What is the general treatment for supernumerary teeth?
extraction before problems arise
The more supernumeraries, the more ___, the ____ the position, the ___ it is to manage.
abnormal; higher; harder
List the indications for removal of conical supernumerary teeth?
- if it erupts
- inverted
- displacing adjacent teeth
- producing diastema
- delaying eruption of permanent tooth
When should you NOT remove conical supernumerary teeth?
If the tooth is well above the apices of the permeant tooth, just observe
What does the typical supernumerary tooth resemble?
Resembles a normal tooth in morphology & commonly produces crowding or displacement
What is the recommended treatment for typical supernumerary teeth?
Extract the tooth most dissimilar to the contralateral tooth unless it is severely displaced
The recommended treatment for typical supernumerary teeth is to extract the tooth more dissimilar to the contralateral tooth unless:
it is severely displaced
What is the incidence of impactions and ectopic eruptions?
incidence= 1.7%
Females (1.17%); males (0.51%)
What percent of the time do bilateral impactions occur?
8% of the time
What percent of the time do mandibular canine impactions occur?
0.35%
List the etiologies for impactions and ectopic eruptions:
- local hard tissue obstruction
- local pathology
- disturbance of normal development of the incisors
- hereditary or genetic factors
List the signs that might lead you to believe that the canines are impacted:
- canine is unerupted after 75% of its root development
- the contralateral tooth has erupted for at least 6 months with complete root formation
- two years after the adolescent growth spurt were passed
- 6 months after canine tooth completed was passed
- sufficient space for eruption (yet not erupted)
- arch length deficiency
What percent of palatal canine impactions had sufficient space for eruption?
85%
83% of labial canine impactions showed an:
arch length deficiency
What can be used to diagnose impacted teeth?
- PA radiographs
- Occlusal radiographs
- CBCT imaging
With PA radiographs, what technique should be used?
Clark’s Technique (SLOB rule)
What degree to the occlusal plan can you see impacted canines on an occlusal radiograph?
110 degree vertex occlusal
Are convention radioagraphs or CBCT better for accurate and precise examination methods for displaced maxillary canines?
CBCT- conventional radiographs demonstrated a more subjective diagnosis
