Malocclusions in Orthodontics Flashcards
What is malocclusion?
An appreciable deviation from normal occlusion.
What percentage of malocclusions are due to a variation of normal development?
95%
What percentage of malocclusions have an identifiable cause?
5%
What are the genetic influences?
Skeletal pattern
Some syndromes such as muscular dystrophy
Tooth morphology
What are the environmental influences?
Soft tissues (forces created by lips, tongue, PDL)
Habits
Local factors (retained deciduous teeth, missing teeth)
Pathology (cleft lip and palate)
Trauma
What is a class I incisor relationship?
The lower incised edge lies on or below the cingulum plateau of the palate surface of the upper incisors.
Features of a class I?
Usually skeletal 1 but may be mild C2 or C3
AOB
Crossbites
Dental issues of a class I?
Crowding Spacing Bimaxillary proclination Vertical anomalies - AOB Transverse anomalies - Crossbites, scissorbites
How is crowding managed in a class I?
Creation of space from extractions or arch extension
How is spacing managed in a class I?
Open space and place prosthesis
Close space with appliances
How are scissorbites managed in class I?
Mandibular expansion and maxillary contraction
If severe may need surgery
How are crossbites managed in class I?
Maxillary expansion but before planning treatment, consider if there is a displacement or true asymmetry and manage appropriately. Can be treated with: URA with midline screw/coffin spring Quadhelix RME AW expansion in FA Expansion arch (attached to molar tubes) Surgical assisted expansion
What is the definition of a Class II DIV 1 incisor relationship?
The lower incisor edges lie palatal to the cingulum plateau of the upper incisors
Upper incisors are proclined or of average inclination with an upper overjet.
Or
The upper incisors are slightly retroclined with an upper overjet.
What are the features of a class II?
76% usually have a skeletal 2 base
If skeletal 1, incisor relationship is usually due to a habit
Class II incisor relationship with proclined or average upper incisors
Average or lower face height
Increased overjet
Overbite is usually deep and often incomplete
Buccal segments may have crossbites buccal/lingual
Treatment options for Class II div 1
URA (simple tipping) Functional appliances (in growing patients) Fixed appliances (if skeletal problem allows camouflage) Orthognathic surgery (when too severe for orthodontics alone)
What is the definition of a Class II div 2?
The lower incisor edges lie palatal to the cingulum plateau of the upper incisors. Upper incisors (and usually lowers) are retroclined with minimal OJ
What are the features of a Class II Div 2?
Usually skeletal 2 base, although could be skeletal 1, or skeletal 3. Tendency for scissor bite Retroclined upper and lower incisors Overbite is usually deep Overjet is reduced usually Extruded upper incisors Scissorbite common in premolar region Crown-root angle may be decreased Lower face height lower MMP angle lower gonial angle
Treatment options for Class II div 2?
URA (to reduce OB with anterior bite plane)
Modified functional appliance (cantilever springs behind the upper incisors to proline the maxillary incisors)
Fixed appliances (likely to need torque to upper incisors)
Avoid extractions in low MMP angle cases as space closure can be difficult
Carefully consider extraction decision, if necessary take 5’s rather than 4s to minimise lingual movement of LLS.
Orthognathic surgery
What is the definition of a Class III incisor?
Lower incisor edge lie anterior to cingulum plateau of the palatal surface of the upper incisors.
What can a Class III be due to?
Genetics - skeletal pattern
Patients with CLP may present with a III Malocclusion
Features of a Class III?
Lower cranial base angle, forwards position of mandible
Normal or lower MMP angle and lower face height
Class III Molar relationship
Reverse Overjet
Reduced Overbite
Incisors compensate for skeletal base ie proclined maxillary, retroclined mandibular incisors
Can have displacements to obtain posterior occlusion due edge to edge incisor contact or unsatisfactory transverse buccal segment relationship
Treatment options for a class III?
Growth modification Orthodontic camouflage Orthognathic surgery Anterior cross elastics Protraction headgear
