Dinensional Changes Of Dental Arch Flashcards
Dental arch define.
The measurement through the contact point of teeth
Define the alveolar arch.
The measurement of the arch of the alveolar process
Affected by orthodontic movement
Teeth cannot move beyond limits of bone
Basal arch
The measurement of apical base arch
when does the Late mesial shift occur?
Occurs 11-14 years
what is the most important dimension
Arch perimeter
Arch depth (length)
Little clinical significance
Reflects circumferential changes
To measure it used the Midline between central incisors tangent distal of primary 2nd molars or premolars
intercanine width is increased how
it is slightly increase due to distal tipping of primary canines into primate space while mandibular permanent incisors erupt
overbite is correlated to
vertical facial dimensions
overjet influenced by
lip , tongue function and digit habits
overjet correlated to
anterio posterior skeletal relationship
Late lower incisor crowding (tertiary crowding)
One of the most common problems
occurs both in adolescence& post adolescence
High relapse Rate
What is the consequences if tertiary crowding is not treated?
Increase crowding
Width and length decrease
what are the 3 theories of Late lower incisor (teirtiary)
Lack of “ normal attrition “ in the modern diet
pressure from 3rd molar
Late Mandibular growth:
displaces lower incisors lingually
Why does root resorption happen during orthodontic treatment
Movement of teeth back and forth by orthodontic appliances
Duration of treatment
Correction of impacted cuspid
Ectopic teeth
teeth that erupt away from their normal position
What is the most common ectopic eruption
maxillary 1st molar and canine
Treatment of ectopic eruption include
Surgical uncovering
Re-positioning
Orthodontic treatment
early benefit from force of eruption
Difference between ectopic and impactation
ectopic teeth : erupt away from normal position
Impacted teeth cannot erupt due to impingement
-Tooth can be both impacted and ectopic
What is the most common impacted teeth after 3rd molar
Maxillary canines = 2% caucasians
often requires orthodontic treatment
Palatal impactions 2X as common as buccalaA l impaction
Treatment of impacted Max central incisor caused by supernumerary tooth
Remove supernumerary teeth ASAP
in the presence of sufficient space
central incisors superficially placed
hypodontia
if patient is missing 1-6 teetth
Oligodontia
missing 6+ teeth,
usually bilateral:
Anodontia
Complete Absence of teeth
What are the most frequently missing teeth?
Rank
- Mandibular 2nd molar
- Maxillary Lateral incisors
- maxillary 2nd premolars
Do men or women have more missing teeth
women have more missing teeth
Supernumerary teeth
less common than congenitally missing teeth
Mostly seen in maxilla- premax region
TWICE AS OFTEN IN MEN THAN WOMEN
Classification of supernumerary teeth
Teeth with conical crowns
Teeth of normal form and size
Teeth with abnormal size and cuspal form
why do maxillary 1st molars in 3% of north American children have ectopic eruption due to
Large teeth (primary and permanent)
Decreased arch perimeter
Posterior position of upper arch
atypical angle of eruption of the 1st molar.
why impacted maxillary canine are common
Deviation from path of eruption
Long Path of eruption
It relies on lateral incisor root for guidance
bc of chronology of eruption:( after 1st premolar)
genetic susceptibility
when maxillary canines impact what is the palatal impaction vs buccal impaction ratio
Palatal impaction 2/3
Buccal impaction 1:3
what are the effects of aging in teeth and supporting structure
Decrease of pulp chamber size as age increases
Clinical crown gets longer due to adaption to vertical jaw growth
Passive eruption does not occur if gingival tissues are healthy
Passive eruption
Actual gingival migration of the attachment without any eruption of the tooth
Inter- premolar(PM) width
slightly increased
The center of the premolar crowns are placed more buccally than molar crowns
Inter molar width
Inter molar width decreases with late mesial shift
what is E Space
the difference in MD width between 2nd molar and 2nd permanent premolar
