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 seven conditions are known to results in congenitally missing teeth?
- ectodermal dysplasia
- Hypothyroidism
- Down syndrome
- Cleft palate
- Genetics
- Radiation
- Random
Groups of syndromes causing missing or peg shaped teeth, thin, sparse hair & absence of sweat glands:
ectodermal dysplasia
Cleft palates occur in _____ births
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 for there to be a successor if the primary tooth bud is missing
Is it possible to have missing permanent teeth even when there is a primary tooth?
Yes
What is the INCIDENCE of hypodontia in the general population?
General population: 2-10% (excluding third 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 an etiologic factor in hypodontia?
MSX1
PAX9
AXIN2
List two 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 second premolars
Maxillary second premolars
Maxillary lateral incisors
Maxillary second molars
Are maxillary or mandibular second premolars missing more often?
Mandibular second premolars
What are the REPLACEMENT treatment options for hypodontia cases?
- Prosthetically
- Transplantation
- Implant
What are the treatment options for hypodontia cases?
- 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 chosen treatment for hypodontia?
Retains primary tooth until close to implant placement time to ensure good bone
What do you need for proper canine substitution?
- similar color to central incisor
- narrow width of CEJ
- relatively flat labial surface
- narrow mid-crown BL width
- enameloplasty
What is the order of canine enamelopalsty?
- cusp tip
- mesial & distal (often underperformed)
- labial ridge
- add mesial composite
- line angles
Extra, supernumerary teeth have great potential to:
Distrupt 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? Permament 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?
In the maxillary midline
Do mesiodens often exist singularly or in combination?
They are most often singular, but they can also exist in combination
Can mesiodens deflect teeth?
Yes
What is the general treatment for supernumerary teeth?
Extract before problems arise
The more supernumeraries, the more _____, the ____ the positon, 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 permanent tooth, just observe
What does a typical supernumerary tooth resemble?
Resembles a normal tooth in morphology and commonly produces crowding or displacement
What is the recommended treatment for typical supernumerary teeth?
Extract the tooth more dissimilar to the contralateral tooth unless its 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: 1.17%
Females 1.17%
Males 0.51%
What percent of the time does B/L impactions occur?
8%
What percent of the time does 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 has passed
- 6 months after canine root completion 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 diagnosed impacted teeth?
-periapical radiographs
-occlusal radiographs
-CBCT imaging
With periapical radiographs, what technique should be used?
Clark’s technique (Slob rule)
What degree to the occlusal plane can you see impacted canines on an occlusal radiograph?
110 degree vertex occlusal
Are conventional radiographs or CBCT better for accurate and precise examination methods for displaced maxillary canines?
CBCT- conventional radiographs demonstrated a more subjective diagnosis
