Class II Malocclusions Flashcards
What is the BSI definition of a class II div 1 malocclusion?
The lower incisal edges lie posterior to the cingulum plateau of the upper incisors.There is an increase in overjet.The upper central incisors are proclined OR of average inclination.
What are is the incidence of class II div 1 malocclusions?
15-20% of the population.
What are is the incidence of class II div 2 malocclusions?
10% of the population.
What is the reasoning for treating a class 2 div 1 malocclusion?
Aesthetic concernsSocial concernsConcerns with dental health, if overjet >9mm then trauma is twice as likely, particularly if patient has incompetent lips.
What is the IOTN score of an overjet >9mm?
5a, indicating a high need for treatment.
What skeletal pattern are class II div 1 malocclusions commonly found in, and why?
Usually associated with a class II skeletal pattern, usually due to a retrognathic mandible - but can also be due to maxillary protrusion and rarely class 3.No associations with transverse problems, but found in a wide variety of vertical patterns.
What can an overjet be caused by?
Skeletal pattern, tooth inclination, or a combination of both.
What are the typical ranges for angles identified on a cephalogram of a class II occlusion?
SNA = usually the sameSNB = usually decreasedANB = >5
How can a class II skeletal pattern be defined?
The maxilla is greater than 3mm in front of the mandible.
What complications can a lip trap pose to orthodontic treatment?
May procline the upper incisors, and could cause relapse of over-jet if it persists at the end of treatment.
What is a class II division 2?
The lower incisal edges lie posterior to the cingulum plateau of the upper incisors.There is an little to no increase in overjet.The upper central incisors are retroclined or of average inclination.
In a class II, where would the mesio-buccal cusp of 16 likely occlude to?
The marginal ridges of 45 and 46
In a class II, where would the incisal edge of 13 likely occlude?
Mesially to the incisal edge of 43.
What are the occlusional features of a sucking habit?
Proclination of upper anteriorsRetroclination of lower anteriorsLocalized AOB or incomplete OBNarrow upper arch (may see unilateral posterior crossbite)
What are the dental features in class II div 1 patients?
Proclined upper incisors Increased OJ Class 2 molars and canines
What soft tissue problems are associated with class II div 1 malocclusion?
Often incompetent lips due to prominence of incisors and/or underlying skeletal pattern. Inability to achieve an anterior oral seal May have lip trap and tongue thrusts
What makes a class II div 1 malocclusion amendable to correction via removable appliance therapy?
Generally URA have a limited role in the treatment of increased overjet’s unless there is a very mild class II, when overjet’s is due to incisor proclination, there is favorable overbite and only after specialist assessment.
What are the treatment options for a class II div 1 malocclusion?
Accept and monitor – when there is reduced risk of trauma Attempt Growth modification – twin block; Frankel 3 or headgear URA – limited use but Robert’s retractor can be used Fixed appliance Orthognathic surgery – only used when growth is complete and where there Is severe skeletal A/P discrepancy or vertical direction
What is ANB for class II patients?
> 4 degrees
Which skeletal patterns do class IId2 patients present with?
Typically class II but can be I or III
Typically what FMPA angle would a class II d2 patient have?
Reduced
When is the time when growth modification can be considered for orthodontic patients?
Ideally around time of growth spurt Boys 14 +/- 2 years Girls 12 +/- 2 years
List the skeletal features commonly associated with class II div 2 patients.
AP = Usually mild/moderate class 2 skeletal base, but can be class 1 or class 3.Vertical = Reduced FMPA angle and prominent chin (progenia).
List the soft tissue features commonly associated with class II div 2 patients.
High resting lower lip line, result of decreased lower facial height.Marked labio-mental fold.High masseteric forces (causes problems for space closure.Issues with lip trap from escape effect of lower lip.
List the dental features commonly associated with class II div 2 patients.
Retrocliniation of the upper centralsOften crowded upper 2’s (and rotated)Reducded arch length, which exacerbates crowdingPoor cingulum for lateral incisorsTypically deep overbite and reduced overjetIncreased inter-incisal angle
What is the average inter-incisal angle?
135 degrees
For what reasons would you treat a class II div 2 patient?
Aesthetic concernsDental health concerns:- Traumatic overbite- IOTN 4f
What are the main treatment options for class II div 2 patients?
AcceptGrowth modificationCamouflageOrthognathic treatment
For what reasons might you accept a class II div 2 malocclusion?
Acceptable aesthetics Patient not concerned/suitableOverbite not a significant problem
What functional appliance would you use for growth modification in a class II div 2 case?
Modified twin block with springs/screws Followed by upper sectional fixed appliance
What is orthodontic camouflage?
Accept underlying skeletal base relationshipTreatment aim is to get class I incisor relationshipOrthodontic extraction may be required to make space
When should orthognathic surgery be considered?
When too severe a malocclusion for orthodontics alone.Non-growing patientsProfile concerns
