open bite / orthodontic courses by Indian dental academy

INDIAN DENTAL ACADEMY

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OPEN BITE


INTRODUCTION

• Open bite is a malocclusion that occurs in the vertical plane, characterized by lack of vertical overlap between the maxillary and mandibular dentition. Open bite can occur in the anterior and the posterior region and are called anterior open bite and posterior open bite respectively


Definitions I. Open bite is defined as a condition where

a space exists between the occlusal or incisal surfaces of the maxillary and mandibular teeth in the buccal or anterior segments when the mandible is brought into a habitual or centric occlusion (Graber).


II. According to Moyers, there are 2 definitions of open bite.

• The first defines open bite as the absence of vertical incisal overlap.

• The second defines open bite as the absence of an occlusal stop.

• Open bite is the failure of a tooth or teeth to meet antagonists in the opposite arch or the occlusal planes


• III. Proffit defined Over Bite as the vertical overlap of the incisors. Normally the lower incisor edges contact the lingual surface of the upper incisors at or above the cingulum (i.e. 1-2 mm overbite). In open bite, there is no vertical overlap and the vertical separation is measured.


CLASSIFICATION I. According to location Open bite divided into:-• Anterior open bite• Posterior open biteII. According to Moyers:• Simple open bite:• When the cephalometric analyses reveal no

abnormal measures and the sole problem is the failure of some teeth to meet the line of occlusion.

• Complex or skeletal open bite:• When the cephalometric analyses reveal

disharmonies in the skeletal components of the anterior face height.


Etiology of Open Bite Multifactorial:

• Disturbances in the eruption of teeth and alveolar growth. E.g. Ankylosed primary molars.

• Mechanical interference with eruption and alveolar growth. E.g. Finger sucking, foreign body in mouth (Pins, pencil)

• Vertical skeletal dysplasia which may be genetically determined.


. Mouth breathing : could cause different head, jaw and tongue

position which would effect the jaw growth and tooth positions.

• Different postures seen in mouth breathing:– Lowering the mandible– Positioning the tongue downward and forward– Tipping back of the head.


• The type of Open Bite associated with mouth breathing is called ‘Skeletal Open

Bite or adenoid facies.

Characterized by– Excessive eruption of posterior teeth– Tendency towards Maxillary constriction– Excessive overjet– Anterior open bite


• Tongue thrust: Tongue thrust itself is not responsible for anterior open

bite

• Tongue thrust is a adaptive feature of anterior open bite

• Tongue thrust is of 2 types – Simple tongue thrust swallow - Complex tongue thrust swallow


• Simple tongue thrust- The teeth are in occlusion, the lips tightly closed, tongue held against palate behind the anterior teeth.

• Complex tongue thrust- Associated with chronic maso respiratory distress, mouth breathing, tonsillitis or pharyngitis.

Root of the tongue may enchroach on the enlarged facial pillars. To avoid this enchroachment, the mandilble reflex drops separating the teeth providing more room for the tongue to thrust forward during swallowing to a more comfortable position


• Thumb sucking can cause– Flarred and spaced maxillary incisors– Anterior open bite– A narrow upper arch

Anterior open bite associated with thumb sucking arise by

- interferences with normal eruption of incisors and excessive eruption of posterior teeth.


• When the thumb or finger is placed between the anterior teeth , the mandible must be positioned downward to accommodate it.

The thumb impedes incisor eruption. The separation of jaw alters the vertical equilibrium on the posterior teeth. There is over or supra eruption of posterior teeth.

1mm of elongation posteriorly causes 2mm of bite opening.



•Rotation of the jaws


• Lip sucking and lip biting.• Foreign bodies: Pipes, pen, pencil.• Trauma or pathology of condyle.


Clinical Considerations • Various forms of anterior open bite may be

observed depending on the severity of the malocclusion

1. Cases with an overjet combined with an open bite of less than 1mm can be designated as Pseudo Open Bite problem.

2. Simple open bite exists in cases in which more than 1mm of space may be observed between the incisors but posterior teeth are in occlusion.


3. Complex open bite exists in those case in which open bite extends from premolar or deciduous molars of one side to that of the other.

4. The compound or infantile open bite is completely open including the molars.

5. The iotrogenic open bite is the result of orthodontic therapy which produces atypical configurations because of appliance manipulation or adaptive neuromuscular response.


• In mixed dentition period various therapeutic measure may cause open bite.

1. Open activator with high construction bite can cause tongue thrust and resultant open bite during intrusion of posterior teeth. Posterior open bite can be caused in deciduous molar area.

2. In expansion treatment- Buccal segment are tipped buccaly with elongation of lingual cusps. This creates prematurity and effectively opens the bite.

3. In distalization of maxillar first molar with extraoral force the molars are often tipped down and back, elongating the mesial cusps. This creates a molar fulcrum that opens the bite.


Cephalometric criteria • A proper cephalometric analysis enables a

classification of Malocclusion.

In vertical growth pattern: Dentoalveolar symptom

– Protrusion of upper anterior teeth.– Lingual inclination of lower incisors.

Horizontal growth pattern: - Tongue thrust and posture may cause

proclination of upper and lower incisors


• Lateral open bite can be considered dentoalveolar in combination with infra occlusion of molars.

Causes– Cheek bite, lateral tongue thrust



• Skeletal open bite– Excessive anterior facial height– Short posterior face height– Mandibular base is usually narrow– Presence of antegonial notching.– Symphysis in usually narrow and long– Ramus is short- Growth pattern is vertical


• Features of Anterior Open Bite:

– Open bite limited to anterior segment, often asymmetrical

– Proclined maxillary or mandibular incisors– Spacing between maxillary and mandibular

anteriors.– Narrow maxilar arch.– ‘Fish mouth’ appearance.


• Features of Skeletal Open Bite:

Extra oral features:– Long face due to increased LAFH– Incompetent lips– An increased mandibular plane angle– An increased gonial angle– Marked antigonial notch– A short mandible is a possibility– Maxillary base may be more inferiorly placed


• Intra oral features

– Mild crowding – Gingival hypertrophy – Maxillary occlusal and palatal plate tilt

upwards.– Mandibular occlusal plane canted downwards


• Posterior Open Bite:

Causes:

1. Mechanical interference with eruption: Either before or after tooth emerges from alveolar bone. Mechanical interference may be

– Ankylosis of tooth to the alveolar bone(Trauma) E.g.Trauma, supernumerary teeth, non resorbing deciduous roots.

After the tooth emerges from the alveolar bone,

– Pressure from the soft tissues (Cheek,finger,tongue) can be obstacle to eruption.


2. Failure of the eruptive mechanism of tooth so that expected amount of eruption does not occur.


TREATMENT OF OPEN BITE:

Therapy depends on localization and etiology of M.O. Habit control and elimination of abnormal perioral muscle function are causal therapeutic approaches to dentoalveolar open bite.


Appliance used to remove the etiology of Anterior Open Bite


• Treatment in Decidious Dentition:– Many instances open bite improves as the habit is

stopped– Screening appliance can be used

• Screening appliance intercept and eliminate all abnormal perioral muscle function in acquired MO resulting from abnormal habit. mouth breathing, nasal blockage.

• Self correction of M.O is frequently possible


• Another level of intervention is reminder therapy.

1. Bitter medicine may be placed on adhesive type which is wrapped around the thumb.

2. Reward system can be implemented. Reward for not engaging into the habit.

3. Elastic bandage loosely wrapped around the elbow prevents the arm from flexing and fingers being sucked.



• Treatment of Open Bite in mixed dentition:

3 types of Open Bite MO can be differentiated

1. Dentoalveolar Open Bite - In the early mixed dentition – Screening therapy indicatod - In the late mixed dentition – Screening therapy unsuccessful - In such cases fixed appliance treatment is done but long post

treatment retention required.

Swallowing exercise may also bring about reinforcement of mature deglutation pattern for the tongue during both treatment and retention.


• Skeletal Open Bite:

Depends on 2 factors:1.Severity of Malocclusion2.Possibility of dentoalveolar compensation Growth pattern is almost vertical Inclination of maxillary base is decisive in

treatment planning• Rotation of jaw base • Divergent- Prognosis is poor • Maxillary Base• - Tipped downward and forward- Functional

therapy successful


• Functitonal therapy includes Activator FR4 Bionator



- Bionators are used to close open bite- Prevents tongue inserting into the space- Maxillary parts of acrylic joined anteriorly unlike

standard bionator- Anterior part not in contact with the teeth or

alveolar bone- Small white blocks used for stabilization has

indentations on the surface- Bite blocks prevent the posterior teeth from

errupting- Anterior teeth are allowed to erupt freely


open bite activator


- Used in the treatment of dentoalvealor open bite

- Eruption of posterior teeth is prevented- Elongation of anterior teeth encouraged- Acrylic is not ground away from occlusial

surface of posterior teeth- Anterior teeth allowed to erupt freely



3. Combined Open Bite: Because of dual nature of etiology

combined treatment approach is needed. – Elimination of abnormal perioral muscle– Improvement of skeletal relatioship


• Treatment of Open Bite in the mixed and early permanent dentition:– Headgear

• Functional appliance with bite blocks


• Treatment in Permanent dentition– Fixed appliance therapy with screening

appliance– Box elastics– Repelling magnets placed in the posterior bite

plates– Anterior attractive and posterior repelling

mode to achieve normal over bite




Surgical correction: Long face problem

– Treated by intrusion of maxilla. This allows mandible to rotate around the condyle, thereby reducing the mandibular plain angle and shortening the face


Surgical approach involves Le fort 1 down fracture of the maxilla with

superior reposition of the maxilla after removal of the bone from the lateral walls of the nose, sinus and nasal septum. Results are quite stable.


• In mandible, Inferior border osteotomy of the mandible

to reduce vertical height of the chin. Usually a combination of maxillary

intrusion and repositioning of the chin is done.


• Management of Open Bite in M.B.T techniques

• Early management of Open Bite– Finger and thumb appliance which provide a barrier

can be used to correct minor problem– Palatal expansions in narrow maxilla- Helps in

providing space for eruption, ritroclination of incisors.– Help to open the airway and encourage nasal

breathing and provides more room for tongue. - Palatal bars and lingual arches- Reduce the

vertical eruption of molars. www.indiandentalacademy.com

– Posterior bite planes on the upper or lower posterior teeth.

– High pull facebow and chin caps- Limit the vertical eruption of molars.

– Removal of deciduous canines and sometimes premolar in case with significant crowding/protection- Allows eruption and retroclination of incisors.

– Myofunctional therapy benefits in severe cases– Adenoids and tonsils if contributing factors- should be

removed.


Management of Open Bite during full orthodontics treatment:

While non extraction treatment is generally preferred in orthodontics, some Open Bite cases may benefit from extractions. Primarily to allow for eruption and retroclination of incisors.


• Some possibilities are

1. If upper or lower arches show crowding , protrusion then upper or lower bicuspid extraction.

2. Lower arch does not require extraction for lower incisors retraction and molars are more than 3-4mm class II – Extraction of only upper bicuspids considered for retraction and retroclination of incisors.


3. During bracket placement in open bite, upper and lower anterior brackets can be placed 0.5mm more gingivally- Helps to achieve bite closure as treatment proceeds

4. If class II or class III elastics are required- Should be attached posteriorly to premolar rather than molar. They minimize extrusive effect on the back of the arches


open bite / orthodontic courses by Indian dental academy

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