55. Openbite. Prevention and treatment Flashcards
(18 cards)
Open bite
- Deviation in vertical relationship between maxillary and mandibular dental arches
- Lack of contact in vertical direction between opposing segments of teeth
-Degree of openness can vary=>edge-to-edge relationship or some degree of overbite does not qualify as an open bite
Anterior open bite
- Lack of incisal contact between anterior teeth when mandible closed
- Absence of vertical overlap of lower incisors by upper incisors when posterior teeth occluded
-Anterior open bites can occur in all types of occlusion.
Classifications of open bite can be based on
- Region
- Etiological Factors
- Molar Relationship
- Clinical Evaluation
Openbite region classification
- Anterior open bite
- Posterior open bite
Openbite classification based on Etiological Factors
- Dental open bite=>
- Abnormal eruption of incisors
- Dentoalveolar open bite=>
- Change in vertical growth of alveolar component, restricted to anterior teeth w/ normal facial and skeletal features
- Skeletal open bite=>
- Unfavorable vertical growth pattern affecting both anterior and posterior teeth
Openbite classification based on molar Relationship
- Class I open bite
- Class II open bite
- Class III open bite
Openbite classification based on Clinical Evaluation
- Simple=>
- Between incisors
- Complex=>
- Extends from premolars/deciduous molars from one side to other
- Compound/Infantile=>
- Completely open including molars
- Iatrogenic=>
- Consequence of orthodontic or surgical treatment
Etiological factors for anterior open bite
- Genetic/Hereditary and Anatomic Factors
- Neuromuscular Deficiencies
- Mandibular Condyle Resorption
- Environmental Factors
Genetic/Hereditary and Anatomic Factors leading to openbite
- Lower facial height
- Abnormal skeletal size and vertical growth pattern
- Increased tongue size and posture=>(macroglossia, lower tongue posture at rest)
- Unfavorable growth potential=>
- Steep mandibular plane, increased gonial angle, short mandibular ramus
- Increased anterior lower face height, backward rotation of mandible
Neuromuscular Deficiencies leading to open bite
- Muscular dystrophy=>
- Decreased tonic muscle activity and downward mandible rotation
Mandibular Condyle Resorption leading to open bite
- Local causes=>
- Osteoarthritis, avascular necrosis, trauma
- Systemic causes=>
- Rheumatoid arthritis
- Idiopathic condylar resorption (bilateral, no obvious etiology)
Environmental Factors leading to open bite
- Habits=>
- Pacifier and digit sucking
- Tongue thrusting
- Infantile swallowing, mouth breathing
- Ankylosis of anterior teeth, severe crowding of anterior teeth
- Arrested tooth eruption (idiopathic or iatrogenic)
- TMJ pain and dysfunction=>
- Mandibular condyle resorption and open bite malocclusion
Causes of mouth breathing=> enlarged adenoids/tonsils, swollen nasal turbinates, deviated nasal septum, inflamed nasal mucosa
Etiological factors for posterior open bite
- Before or after tooth eruption from alveolar bone=>
- Ankylosis of tooth to alveolar bone
- Failure of eruptive mechanism
- Lateral tongue thrusting
-Causes of ankylosis of tooth to bone=>trauma, supernumerary teeth, non-resorbing deciduous roots
-Causes of failure of eruption=>
-craniofacial syndromes=> cleidocranial dysplasia and Carpenter’s syndrome
Clinical features of dentoalveolar open bite
- Proclined upper anterior teeth
- Lack of overlap between maxillary and mandibular anterior teeth
- Narrow maxillary arch=>lower tongue posture
- Normal facial proportions (normal craniofacial pattern)
- Infraposition of anterior teeth
- Reduced anterior dentoalveolar height
- Normal or slightly excessive molar height
- Divergent upper and lower occlusal planes
Clinical features of skeletal open bite
- Excessive anterior face height=>lower third
- Decreased posterior face height
- Steep mandibular plane w/ short ramus
- Excessive eruption of maxillary posterior teeth
- Lip incompetence (interlabial gap more than 4mm)
- Increased gonial, mandibular plane, and occlusal plane angles
- Decreased palatal plane angle
- Tendency to class II malocclusion w/ mandibular deficiency
- Tendency to posterior crossbite=>narrow maxilla
-Anterior open bite (not always present)
-Occasional maxillary retrognathia
Diagnostic aids used for identifying and assessing open bite
- Anamnesis=>
- Questions about oral habits
- Clinical Examination
- Cephalometric Analysis
Cephalometric Analysis of Dentoalveolar open bite
- Vertical growth pattern=>
- Protrusion of upper anterior teeth
- Lingual inclination of lower incisors
- Horizontal growth pattern=>
- Upward and forward tipping of maxillary base
- Tongue posture and thrust causing proclination of both upper and lower incisors
- Anterior teeth under-erupted=>
- Interferences (e.g., habits)
Cephalometric Analysis of Skeletal Open Bite
- Excessive anterior facial height w/ decreased posterior facial height
- Normal mandibular base w/ antegonial arching and short ramus
- Increased bony angle w/ vertical growth pattern
- Upward tipping of forward end of maxillary base and downward tipping of posterior end
- Increased total anterior facial height w/ no difference in cranial base
- Anterior teeth normally or over-erupted
