Definitions Flashcards
Molar Relationship
Class 1
The mesiobuccal cusp of the upper first molar occludes in the buccal groove on the lower fist molar.
Molar Relationship
Class lll
The mesiobuccal cusp of the upper first molar occludes anterior (forward) to the buccal groove of the lower first molar.
Molar relationship
Class ll
The mesiobuccal cusp of the UPPER first molar occludes posterior (behind) to the buccal groove of the lower first molar.
Incisor Relationship
Class l
The LOWER incisor edges occlude with, or lie immediately below the cingulum plateau of the UPPER central incisors.
Incisor Relationship
Class ll div l
The LOWER incisor edges occlude posterior to the cingulum plateau of the UPPER central incisors. The UPPER central imcisors are PROCLINED and there is an INCREASE in the overjet.
Incisor Relationship
Class ll div ll
The LOWER incisor edges occlude posterior (behind) to the cingulum plateau of the UPPER central incisors. The UPPER central incisors are RETROCLINED and there is REDUCED or INCREASED overjet.
The common feature is proclined latetal incisors.
Incisor Relationship
Class lll
The LOWER incisor edges occlude ANTERIOR (infront) to the cingulum plateau of the UPPER central incisors.
The overjet is REDUCED or REVERSED.
Canine Relationship
Class l
The UPPER canine occludes and lies in the embrasure between the LOWER lateral incisors and canine.
Canine Relationship
Class ll
The UPPER canine occludes anterior or lies in the embrasure between the LOWER lateral incisors and canine..
Canine Relationship
Class lll
The UPPER canine occludes posterior (behind) and lies in the embrasure between the LOWER first and second premolars.
Hypodontia
Missing teeth, used when there is congenital absence of one or more primary or secondary teeth.
Causes: can be genetic, with a family history of hypodontia.
Common missing teeth are:
Upper third molars (U8’s)
Lower third molars (L8’s)
Upper premolars (5’s)
Lower premolars (L5’s)
Upper lateral incisors (U2’s)
Lower cental incisors (L1’s)
Oligodontia
More than 6 missing teeth
Anodontia
Total loss of teeth
Supernumerary
AN extra tooth found when there are excess teeth of the normal series.
Most commonly found supernumerary is in the anterior (front) maxillary region.
Types:
*Conical, known as mesiodens.
*Tuberculate
*Supplemental
*Odontomes
Impaction
Failure of eruption of a tooth/canine due to crowding or an obstruction within the dental arch.
Deepbite
Vertical overlap of UPPER incisors OVER LOWER incisors when posterior segment is in occlusion.
UPPER incisors OVERLAP LOWER incisors in excess of 4mm or more.
Normal Overbite
UPPER incisors COVER one-third of LOWER incisors with posterior (back) segment in occlusion.
Increased Overbite
UPPER incisors COVER, MORE than one-third of LOWER incisors when posterior segment is in occlusion.
Decreased Overbite
UPPER incisors cover LESS than one-third of LOWER incisors when posterior segment is in occlusion.
Incomplete Overbite
LOWER incisors DO NOT come into contact with hard or soft tissue.
Complete Overbite
LOWER incisors DO come into contact with hard or soft tissues.
Anterior openbite (AOB)
No vertical overlap of the upper & lower incisors when posterior segment is in occlusion.
Posterior openbite (POB)
No vertical overlap of upper & lower posterior teeth when posterior segment teeth are in occlusion.
Crossbites
An abnormal relationship between opposing teeth in buccopalatal or buccolingual direction.
Posterior crossbite
Buccal cusps of lower teeth occlude buccal to buccal cusps of upper teeth when patient is in full
occlusion.
Anterior crossbite
One or more of the maxillary incisors occlude lingual to lower incisors with posterior terth in occlusion.
Lingual crossbite
Buccal cusps off lower teeth occlude palatalto palatal cusps of upper teeth when patient is in full occlusion.
Overjet
Distance between upper & lower incisors in horizontal plane.
Normal overjet is 2-4mm.
Bimaxillary proclination
Occlusions where both upper & lower incisors are proclined.
Centre of resistance
Point in the body where resistance to movement is concentrated.
Force movement
The component found within a force that causes rotational movement only.
Force couple
In fixed appliances, when an archwire connects into the bracket slot a force couple is created, which will achieve rotation, inclination of teeth & torque.
Dental panoramic tomography (DPT)
A radiograph that gives a two-dimensional view of the upper and lower jaws (maxilla & mandible)
Cephalometric radiograph
A true lateral view of the skull, a two-dimensional image of a three-dimensional object presenting the skull & facial bones.
Upper standard occlusal radiograph (USO)
A radiograph of the anterior part of the maxilla and anterior teeth.
Parallax
A technique used when assessing or localising the position of unerupted tooth/teeth.
