Vertical and Transverse Malocclusions Flashcards
What plane is angle’s classification and BSI classification in?
Sagittal
What impacts do vertical and transverse malocclusions have on patients?
- Aesthetics
- Function
- Treatment Need
What are some types of transverse malocclusions?
- Facial Asymmetry
- Mandibular Buccal Crossbite (Uni/Bilateral + Localised/Generalised)
- Scissorsbite (Uni/Bilateral + Localised/Generalised)
- Dental vs facial midline deviations
- Lateral functional shift
If a patient has bilateral generalised crossbite/scissorsbite, what is the likely aetiology?
Skeletal
What are the possible aetiologies of facial asymmetry and how do you determine it?
Skeletal or soft tissue or combination of both
Using Radiographic tools: OPG, Lat Ceph, Posteroanterior cephalogram (PA ceph)
What are the different types of facial asymmetry?
- Middle (max) or lower vertical third (man - condyle, body or ramus) asymmetry or both
- Transverse cant in occlusal plane
- Midline deviation
What are the possible Skeletal asymmetry aetiologies?
- Unilateral excess growth
- Unilateral condylar hyperplasia
- Hemimandibular elongation (AP growth)
- Hemimandibular hyperplasia (AP + Vertical growth) - Unilateral deficiency
- Unilateral deficient condylar growth (due to trauma or infection)
- Hemifacial microsomia
- Unilateral idiopathic condylar resorption (teenage females, resulting in AOB + Class II malocclusion)
Definition of crossbite
Discrepancy in the buccolingual relationship of the upper and lower teeth (ant/post)
Convention: position of lower relative to upper
Definition of buccal crossbite (post)
Buccal cusps of lower teeth occlude buccal to the buccal cusps of upper teeth
Definition of lingual crossbite (post)
Buccal cusps of lower teeth occlude lingual to the lingual cusps of upper teeth
Scissorsbite
Skeletal causes of mandibular buccal crossbite
- True/Absolute transverse discrepancy
- Maxillary constriction
- Wide mandible
- Combination - Relative transverse discrepancy
- Anterior-posterior relationship
- Skeletal asymmetry
Features of mandibular buccal crossbite
- Reduced intermolar width (max) compared to norms/man
- Reduced arch perimeter
- Increased curve of wilson (DAC)
- Increased buccal corridors
When does maxillary constriction not lead to buccal crossbite
When there is DAC by having an increase in the curve of wilson (increased buccal inclination of max and increased lingual inclination of man)
Feature: both max and man skeletal widths are narrow
Dental causes of mandibular buccal crossbite (usually unilateral + localised)
Displacement
Rotation
Inclination
of tooth
Soft tissue causes of mandibular buccal crossbite
- Non nutritive sucking habits (constriction of max arch by increased lingual pressure of buccinators and reduced buccal pressure from lowered tongue)
- Macroglossia/lateral tongue spread
- Mouth breathing
Additional causes of mandibular buccal crossbite
- Cleft lip and palate (teeth grows upwards towards cleft –> AOB, surgery when theyre 1 causes scarring and restricts growth of maxilla)
- Lateral functional shift (Single tooth interference, Arch width discrepancy)
What are the differences between a patient with marked and moderate bilateral maxillary constriction?
Marked: CR=MI, bilateral posterior crossbite
Moderate: CR=/ MI, posterior interference to closure, lateral shift into apparent unilateral posterior crossbite
Skeletal and Dental causes of Scissorsbite
- True/Absolute transverse discrepancy
- Mandibular constriction
- Wide Maxilla
- Combination - Relative transverse discrepancy
- Anterior-posterior relationship (Class II patient)
- Skeletal asymmetry
Dental:
Displacement
Rotation
Inclination
of tooth
Causes of Dental vs Facial midline deviations
Skeletal:
1. Skeletal asymmetry:
Chin point deviation
2. Lateral functional shift
Dental:
1. Crowding/Malalignment/ Tooth displacement
2. Missing teeth
3. Irregularly sized teeth (eg. peg shaped lateral)
Treatment options for typical skeletal asymmetry
Depends on the cause.
If cause is:
1. Deficient growth - early treatment
2. Excess growth - wait for growth cessation before proceeding with orthodontic camouflage or surgery; UNLESS aesthetic/functional concerns
Treatment options for lateral function shift
To be corrected ASAP (even if CR is symmetrical, it can remodel to become permanent asymmetry)
Eliminate the cause!
1. Dental interference
2. Maxillary constriction
Treatment options for mandibular buccal crossbites/Scissorsbite
Depends on the cause!
If patient is still growing and cause is:
1. Maxillary constriction or retrusion - Growth modification (Reverse full headgear/facemask for retrusion)
2. Habits - early habit cessation
3. Skeletal Class II - Growth modification (Twinblock)
If patient is post pubertal and cause is:
1. Dental - align teeth
2. Skeletal - Orthodontic camouflage or orthognathic surgery (severe cases)
Orthopedic expansion devices to correct maxillary constriction
- Removable hyrex expander
- Banded hyrax expander
- W-arch
- Quadhelix
Treatment for dental midline deviations
Depends on the cause!
1. Premature loss of primary tooth - early intervention to open space for unerupted permanent teeth
2. Extractions in contralateral quad of crowding/with midline deviation
What are some types of vertical malocclusions
- Open bite
- Deep bite
- Anterior
- Posterior
What is the definition of anterior open bite (AOB)
Vertical overlap does not exist when the buccal segments are in occlusion
What is the definition of posterior open bite (POB)
(Inter-occlusal) space between posterior teeth when the other teeth are in occlusion (Occurs less frequently)
What are the causes of anterior open bite?
Skeletal, Dental, Soft tissue and others
Skeletal:
1. Vertical growth pattern
Dental:
1. Bimaxillary proclination
2. Impacted tooth (localised)
3. Ankylosis of traumatised teeth (localised)
Soft tissue:
1. Non-nutritive sucking habits
2. Forward resting tongue posture
Others:
1. Condylar degenerative diseases - Idiopathic condylar resorption, Juvenile rheumatoid arthritis
2. Trauma - Arrested condylar growth/ Condylar ankylosis
3. Cleft alveolus
How does a vertical growth pattern cause AOB?
- Excess maxillary height (esp in the posterior region)
- Upward tipping of palatal plane anteriorly
- Excess vertical growth of maxillary posterior dentoalveolar complex (molars)
All these result in a downwards and backwards mandibular rotation.
What are some signs of vertical maxillary excess?
Increased incisor display at rest (not due to short upper lip or extruded incisors)
What are the Lat ceph features of a skeletal AOB
9
- Short ramus (short PFH, Long AFH)
- Reduced UAFH:LAFH
- Antegonial notching
- Obtuse gonial angle
- Divergent occlusal planes
- Distal condylar inclination
- Straight mandibular canal
- Long and thin symphysis
- Acute intermolar and interincisal angulation
What are the Dental features of a skeletal AOB
- Rotation of the jaws will carry incisors forward,. causing dental protrusion
- Dentoalveolar compensation: over-eruption of anterior teeth
What are the Soft tissue features of a skeletal AOB
- Parallel skeletal findings - Eg. high mandibular plane angle
- Increased inter-labial gap –> lip incompetence
How does sustained forward resting tongue posture cause malocclusion?
It affects teeth in the vertical (AOB) (inhibits eruption) and horizontal (proclination) (pushes teeth forward) planes
How does non-nutritive sucking habits cause AOB?
- Thumb inhibits the eruption of anterior teeth (can be unilateral or central)
- Supra-eruption of posterior teeth due to mouth being open for a long time
How does non-nutritive sucking habits cause AOB?
- Thumb inhibits the eruption of anterior teeth (can be unilateral or central)
- Supra-eruption of posterior teeth due to mouth being open for a long time
What are some features of a patient with a non-nutritive sucking habit?
- Labial displacement of upper incisors (change in inclination)
- Lingual displacement of lower incisors (change in inclination)
- Increased overjet
- Maxillary constriction
What is the main difference between a skeletal open bite and a dental open bite
Where the occlusal planes generally diverge from.
Skeletal: first molar anteriorly
Dental: first premolar anteriorly
What are the treatment goals and options for the excess development of posterior dentoalveolar complex in a GROWING CHILD
Aim: Control eruption of molars
- High-pull headgear
- Posterior bite blocks
Why is treating excess development of posterior dentoalveolar complex in a GROWING CHILD challenging
This is because vertical growth continues into the post-adolescent years.
What are the treatment options for the excess development of posterior dentoalveolar complex in an adult
- Intrusion of molars
- Orthognathic surgery
What are the treatment goals and options for non-nutritive sucking habits in a GROWING CHILD
Aim: Habit cessation to allow for spontaneous resolution
- Reminders
- Appliance therapy eg. tongue spurs (sharp things on the palatal surface of incisors
What treatment option is there if there is no spontaneous resolution of AOB after habit cessation
Active orthodontic closure
1. Vertical elastics for anterior extrusion BUT incisor and gingival display must be checked
2. Extraction therapy - indicated when there is proclination of incisors and crowding.
Skeletal causes of posterior open bite
Skeletal Asymmetry:
1. Unilateral condylar hyperplasia
2. Unilateral idiopathic condylar resorption (ICR) - POB occurs on contralateral side
3. Hemimandibular hyperplasia
Vertical growth pattern:
POB extends posteriorly to 1st molar
Soft tissue causes of posterior open bite
- Macroglossia
- Lateral tongue spread
Dental causes of posterior open bite
- Impaction
- Ankylosis
- Mesial tipping of molars (Early extraction of Es)
- Primary failure of eruption (PFE) - all teeth posterior to affected tooth will be affected as well
Definition of deep overbite
Excessive incisal overlap in the vertical plane (>40%)
What overbite is considered normal?
2-4mm or
25-40% without functional problems
What type of patients often have deep overbites
Class II Div 2 malocclusions
Skeletal features of a deep bite (which parallels soft tissue features)
- Forward and upwards mandibular rotation
- Horizontal palatal plane (parallel to mandibular plane)
- Convergent rotation of maxilla and mandible (anteriorly)
- Low mandibular plane angle
- Reduced LAFH
- Square gonial angle
Dental features of a deep bite
- Jaw rotation carries incisors into an overlapping position
- Upright upper incisors displacing the lower incisors lingually
What are the dental causes of a deep bite
- Excess eruption of anterior teeth (upper and/or lower)
- check gingival margins
- check upper incisor display at rest
- check lower curve of spee (will be increased) - Under eruption of posterior teeth
- Loss of OVD - severe attrition, loss of tooth structure, posterior bite collapse (exo)
- Bimaxillary Retroclination
These can occur simultaneously
What are the treatment options for deep bite + factors to consider
Aetiology dependent!
If cause is:
1. Extrusion of ant - Intrusion of upper and lower incisors +/= incisor proclination with the use of intrusion or utility arches
2. Intrusion of posteriors - Extrusion of upper and lower posterior teeth with the use of Anterior bite plate/Functional appliances, Cervical-pull headgear
3. Very severe - Orthognathic surgery
Factors to note first:
- Incisor display at rest
- Gingival display on smiling
- Interlabial gap
Is deep bite easier to correct in children or adults?
Easier to correct in growing patients.
However, intrusion of anteriors is considered more stable in adults
