BIOMECHANICAL CONSIDERATIONS IN OPEN BITE
INDIAN DENTAL ACADEMY
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DEFINITION Description of open-bite differ among various authors and investigators 1.
2.
3.
Open-bite to be present when there is less than an average overbite. Open-bite to be present when there is edge-to edge relationship. Open-bite to be present when there is definite degree of openness must be present.
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1.
The degree of openness can vary from patient to patient, but an edge-to-edge relationship or some degree of overbite cannot be rightfully categorized as an open-bite.
2.
The loss of contact, in the vertical direction, of segments of teeth can occur between the anterior segments or between the buccal segments.
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The Glossary of Orthodontic Terms defines open bite as a developmental or acquired malocclusion whereby no vertical overlap exists between maxillary and mandibular anterior or posterior teeth.
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Problems Posed by Open Bite Open bite creates significant problems such as
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TMJ disorders Difficulty in speech (dysphonia) Functional imbalance Bad aesthetics Alteration of incisor guidance Reduction of normal functional activity www.indiandentalacademy.com
Etiology •
Can be classified in to • Genetic • Environmental
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1.Genetic factors •
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The genetic component of an open bite is related primarily to the patient’s inherent growth potential. It has been shown that growth patterns are established early in life & maintained in the majority of the individuals. Therefore, a skeletal open bite could be evident in the early mixed dentition. So control of the vertical growth pattern is difficult by orthodontic means alone. However, changes in the dentoalveolar complex may directly affect the most representative skeletal features of an anterior open bite. www.indiandentalacademy.com
2.Environmental Factors 1.
1.
Abnormal function • Thumb or digit sucking habit • Tongue thrusting habit Improper respiration Mouth breathing
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3. 4. 5. 6. 7. 8.
Macroglossia Neuromuscular deficiencies Condyle trauma Trauma of dentition Degenerative diseases Amelogenesis imperfecta
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1.
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Abnormal function Thumb or digit sucking habit • This is one of the most common habits seen in children. • The habit is quite reversible till the age of 3or4 • Beyond this age, this habit becomes the cause of many malocclusions.
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It was noted Cineradiographically that, during strong thumb sucking , the tongue was pressing forcibly against the thumb & lingual surface of the mandibular incisors. Not only this creating a proclination of the mandibular incisors, but the tongue via the glossopalatine muscle, was pulling the soft palate downward & forward. This explains the increased posterior height of the nasomaxillary complex.
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The ramal muscles stabilize the mandible, preventing excessive pressure on the intruded thumb &, of course, keep the mandible disarticulated, permitting the suprahyoids to place downward & backward forces on the body and symphysis, and it probably explains the bending of the body relative to the ramus.
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Tongue thrust habit • Infantile / visceral swallowing is the physiological basis for the neonate/infant to create a proper lip seal during suckling. When the deciduous teeth erupt, the pattern of swallowing changes to adult/mature swallow. If the visceral swallow persists after the 4th year of life, the habit is called retained infantile swallow or tongue thrust.
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Etiology of tongue thrust 1. Genetic factors 2. Learned behaviour 3. Maturational factors 4. Mechanical restrictions • Macroglossia • Constrictive dental abscess • Adenoid hypertrophy • Neurological disturbances • hyposensitive palate • Moderate motor disability 1. Psychogenic factors www.indiandentalacademy.com
2.
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Improper respiration Mouth breathing habit The mode of respiration influences the posture of the jaws, the tongue and to a lesser extent, the head. Hence mouth breathing can result in altered jaw and tongue posture thereby altering the oro-facial equilibrium leading to malocclusion.
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Classification of mouth breathers 1. Obstructive • Complete or partial obstruction of the nasal passage 1. Habitual • Unconsciously performed act whereby breathing occurs despite removal of obstruction 1. Anatomic • Lip morphology does not permit complete closure of the mouth www.indiandentalacademy.com
3.
Macroglossia Can be responsible for splaying the ant. teeth, thus causing an open bite. (Certain features noted during the clinical examination that are indicative of macroglossia are spacing & flaring of the anterior teeth, indentations on the lateral borders of the tongue & lateral extension of the tongue onto the occlusal surface of the lower teeth)
4.
Neuromuscular deficiency (eg. Muscular dystrophy) patients with this neuromuscular disorder cannot properly use their masticatory muscles to close their jaws. As a result the posterior buccal segments tend to supra-erupt , leading to an anterior open bite. www.indiandentalacademy.com
5.
Condyle trauma Results in arrested condyle growth or ankylosis of the condyle which leads to altered vertical growth of the mandible, clinically evidenced as an anterior open bite.
6.
Trauma to dentition Particularly the incisors, can result in an anterior open bite if the damaged teeth becomes ankylosed before the pt finishes growing. www.indiandentalacademy.com
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Degenerative diseases Involving the condyles may develop anterior open bite. Idiopathic condylar resorption & Juvenile rheumatoid arthritis are two pathologic conditions that involve condylar resorption. Clinically, an anterior open bite is evident as the disease progresses.
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Amelogenesis imperfecta As the teeth are rough & sensitive, patients tend not to bring them together which permit elongation of the posterior teeth resulting in anterior open bite.
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Classification •
Open bite is classified on the basis of :
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Region involved
Anterior Posterior
Etiology
Dental Skeletal
positional
Molar relation
Cl-I Cl-II Cl-III
dimensional
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Clinical evaluation
Simple Complex Compound/ Infantile Iatrogenic
1.
An overjet combined with an open bite of less than 1mm can be designated as pseudo-open bite problems.
2.
A simple open bite exists in cases in which more than 1 mm of space may be observed between the incisors, but the posterior teeth are in occlusion.
3.
A complex open bite designates those cases in which the open bite extends from the premolars or deciduous molars on one side to the corresponding teeth on the other side.
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4.
5.
The compound or infantile open bite is completely open, including the molars. The iatrogenic open bite is the consequence of orthodontic therapy, which produces atypical configurations because of appliance manipulation or adaptive neuromuscular response.
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Overview of Open Bite •
ESTHETIC CONSIDERATIONS
1.
Balance between the nose, lips, and chin profile is essential for optimal esthetics. The dentoalveolar open bite malocclusion is esthetically unattractive particularly during speech when the tongue is interposed between teeth and the lips. The lower facial third is elongated in patients with skeletal open bite.
2.
3.
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FUNCTIONAL CONSIDERATION
1.
Tongue posture and function should be primary considerations in Open-bite problems.
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Acc. To Proffit “if a patient has a forward resting posture of the tongue, the duration of this pressure, even if very light could affect tooth position vertically or horizontally”.
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2.
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Differentiation between primary causal and secondary adaptive or compensatory tongue dysfunction is essential. Acc. to Proffit “A tongue thrust swallow is a useful physiologic adaptation if you have an open bite, which is why an individual with an open bite also has a tongue thrust swallow” (i.e. Secondary adaptive tongue dysfunction)
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According to Bahr and Holt, four varieties of tongue thrust may be differentiated
1.
Tongue thrust without deformation:- Despite the abnormal function, no deformations ensues.
2.
Tongue thrust causing anterior deformation:- i.e anterior open bite, sometimes coupled with bilateral narrowing of the arch and a posterior crossbite. Moyers (1964) terms this a simple open bite. www.indiandentalacademy.com
3.
4.
Tongue thrust causing buccal segment deformation:- A posterior open bite is often seen clinically. Combined tongue thrust:- causing both an anterior and a posterior open bite, is another common dysfunction. This is called a complex open bite by Moyers and is more difficult to treat. www.indiandentalacademy.com
According to Rakosi, four varieties of open bite due to tongue posture may be differentiated:
1.
Anterior Open Bite Open bite in a deciduous dentition, caused by a tongue dysfunction as a residuum of a sucking habit.
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Habitual position The tongue positioned forward during functioning, thus impeding the vertical development of the dentoalveolar structures around the upper and lower anterior teeth.
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2. Lateral Openbite Occlusion, In this type of open bite the occlusion on both sides is supported only anteriorly and by the first permanent molars.
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Habitual Position The tongue thrusts between the teeth laterally. The tongue dysfunction occurs in conjunction with a disturbance in the physiologic growth processed around the first and second deciduous molars.
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3. Complex open bite: • Severe vertical malocclusion. The teeth occlude only on the second molars. •
Habitual Position Tongue-thrusting occurs during function. www.indiandentalacademy.com
4. Tongue dysfunction and malocclusion: • In mandibular prognathism, the downward forward displacement of the tongue often causes an anterior tongue-thrust habit. www.indiandentalacademy.com
INFLUENCE OF NASORESPIRATORY FUNCTION 1.
2.
Physiologic adaptations to various types of upper respiratory obstruction (e.g. constricted external nares, deviation septum, nasal polyps, enlarged adenoids, ) initially may lead to altered functional activity of the muscles associated with respiration. It is hypothesized that this change in the level of postural activity of certain craniofacial muscles ultimately may lead to a change in craniofacial morphology, particularly in the vertical dimension www.indiandentalacademy.com
3
4.
5.
Changes in level of activity of certain craniofacial muscles leads to an extension of the head and airway maintenance. This alteration causes a stretching of the masticatory and facial muscles as well as the associated soft tissue. The possible relationship between airway obstruction and aberrant craniofacial growth is the type of patients descried as having ‘adenoid facies.’ www.indiandentalacademy.com
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These patients typically present a mouth- open posture, a small nose with button like tip, nostrils that are small and poorly developed, a short upper lip, prominent maxillary incisors, a trapping lower lip, and a vacant facial expression.
7.
‘Mouth-breathing� individuals classically have been described as possessing a narrow, V-Shaped maxillary arch, a high palatal vault, proclined maxillary incisors, and a Class II occlusion.
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Adenoid Facies Chronically restricted nasal respiratory function
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Cephalometric Criteria A proper cephalometric analysis enables a classification of open bite malocclusions: 1. 2.
Dento Alveolar Open Bite. Skeletal Open Bite. 1. 2.
3. 4.
Positional deviations. Dimensional deviations
Skeletal Class II Open Bite Skeletal Class III Open Bite www.indiandentalacademy.com
Dentoalveolar open bite The extent of the dentoalveolar open bite depends on the extent of the eruption of the teeth. Eg: Supraocclusion of the molars and infraocclusion of the incisors can be primary etiologic factors.
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In vertical growth patterns the dentoalveolar symptoms include a protrusion in the upper anterior teeth with lingual inclination of the lower incisors.
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In horizontal growth patterns, tongue posture and thrust may cause proclination of both upper and lower incisors.
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A lateral open bite may be considered dentoalveolar in combination with infraocclusion of molar teeth.
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Skeletal Open-Bite 1.
2.
3.
Characterized by excessive anterior face height. The major diagnostic criteria, either or both of which may be present , are a short mandibular ramus & a rotation of the palatal plane down posteriorly. The typical growth pattern shows vertical growth of the maxilla (more posteriorly), coupled with downwardbackward rotation of the mandible and excessive eruption of maxillary & mandibular teeth. www.indiandentalacademy.com
4
5
Only two-thirds of this patient group actually have open bite – in others excessive eruption of incisors keeps the bite closed(compensatory dental eruption) -but the rotation of the mandible produces cl II malocclusion even if the mandible is normal size & severe cl II, if the mandible is small. Indeed, the facial disfiguration seen in skeletal open bites can be found without the presence of dental open bites; however, most instances, skeletal open bite is combined with dental open bite www.indiandentalacademy.com
6.
7.
Because of the short ramus and the lower palate, the pharyngeal space is constricted. In order to breathe, these persons keep their tongues forward. Further enhanced by the dental open-bite, there is a tonguethrusting tendencies. Extreme skeletal open bite often are associated with craniofacial malformations, such as the Crouzon’s syndrome patient, in whom there are gross imbalances in skeletal structures in all three dimensions of the face
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In 1964 Sassouni described the skeletomuscular differences between the skeletal open bite & skeketal deepbite
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Skeletal deepbite(hypodivergent): The vertical chain of masticatory muscles, (the masseter & internal pterygoid,) course is essentially a vertical path with the short, thick bellied muscle masses well ahead of molar resistance thus serving to keep buccal segments depressed & promoting a horizontal growth of skeletal pattern.
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Skeletal open bite (hyperdivergent): The same sling of vertical musculature as being long & spindly and coursing obliquely downward & backward. The mass of muscle is well behind the molar resistance thus it does not serve to keep the buccal depressed & hence promotes vertical development.
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Skeletal Open-Bite
1.Positional deviations
2.Dimensional deviations.
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1.Positional Deviations Acc to Sassouni‌ 1. The four bony planes of the face are steep to each other, bringing the center 0 close to the profile.
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2
The anterior arc, therefore follows the convexity of the profile.
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3.
The posterior vertical chain of muscles is arcuate, and the masseter muscle is posterior to the buccal teeth, thus creating a mesial component of forces responsible for the dental protrusion. www.indiandentalacademy.com
4.
The cranial base angle and the gonial angle are obtuse.
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2.Dimensional deviations 1.
The total posterior facial height (S-Go) tends to be half the size of the anterior total facial height (NMe).
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. The Lower Anterior Facial Height exceeds the Upper Anterior Facial Height.
2
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3
The facial breadths tend to be narrow, giving a long, ovoid appearance in the frontal view.
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. The ramus is short with an antegonial notch at its lower border. 5. The mandibular symphysis is narrow anteroposteriorly and long vertically. 4
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6.
7.
There is a lack of mental protuberance development.. The palatal vault is high and narrow.
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Skeletal Class-II Open bite 1.
2.
3.
This combination is primarily an open-bite type, positionally and dimensionally. The major variant here is in the anteroposterior dimensions of the jaws. The maxilla may be longer, and the mandible shorter. The differential evaluation of these two possibilities is important, as the prognosis and the treatment approach may be different. www.indiandentalacademy.com
4.
In some instances, the rotation of the mandible may be purely positional. Often this is due to a downward and backward rotation of the mandible.
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5.
This rotation is associated with excessive extrusion of the molars. If these interferences were removed, the mandible could be permitted to rotate in a closing direction, improving the Class II and the open-bite patterns simultaneously.
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Skeletal Class-III Open bite 1.
This combination consists primarily of an open-bite with a maxilla deficiency or a large mandible.
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Among the facial deformities, these have probably the worst prognosis in terms of dentofacial orthopedics.
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If correction of this open-bite is attempted by rotating the mandible in a closing direction, the protrusion of the chin is increased.
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On the other hand, the reduction of the mandibular protrusion is attempted by rotating the mandible downward and backward, the open-bite is increased.
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Management •
The timing of treatment and determination of growth pattern are crucial. Based on type of dentition, the management can be divided into • Management in deciduous dentition • Management in mixed dentition • Management in permanent dentition
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Management in deciduous dentition 1.
2.
3.
Dentoalveolar Control of abnormal habits and elimination of dysfunction should be given top priority in the deciduous dentition. The anterior open bite improves as soon as the habit is stopped. Treatment with screening appliances is indicated in such open- bite cases. (Tongue crib or oral screen, vestibular screen, reminder appliance, activator, etc.) www.indiandentalacademy.com
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Skeletal A skeletal open bite is seldom observed in the deciduous dentition. Habit control is of only secondary consideration in these cases, retarding the increasing severity of the dysplasia. Phase I Extra oral orthopedic appliances such as chin caps can be used effectively to redirect growth. Phase II Habit control
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Management of mixed dentition •
Dentoalveolar • Early mixed dentition • Screening appliances and habit breaking appliances. •
Late mixed dentition • Multi-attachment fixed appliances (but a long posttreatment retention phase is necessary until the abnormal perioral muscle function can be reduced.) • Swallowing exercises ( swallowing without thrusting, putting the tip of the tongue behind the upper & lower incisors) may reinforce the establishment of a mature deglutitional & functional pattern for the tongue. www.indiandentalacademy.com
Skeletal •
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Management depends on severity of malocclusion and possibility of a dentoalveolar compensation. Growth pattern in this type of problem is almost always vertical. The inclination of the maxillary base plays a vital role in the management. If the jaw bases are divergent, the prognosis is poor. If the maxillary base is tipped downward and forward, functional appliance therapy may be successful. www.indiandentalacademy.com
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Intrusion of buccal segments & extrusion of the incisors, mesial movement of the posterior teeth is also a benificial dentoalveolar measure to help close the bite. Treatment can be undertaken with activators combined with extraction and/or extraoral force application. In extreme vertical growth patterns if the lip sealing ability is disturbed, surgical resection of the mentalis muscle is performed to reduce the ‘golf ball’ chin effect. Schili insists on surgery after eruption of lower canines to enhance stability & bite closure. www.indiandentalacademy.com
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Combined dentoalveolar and skeletal It is likely that most skeletal open bite case are at least partially attributable to abnormal perioral muscle function. So a combined treatment approach is recommended. Elimination of abnormal perioral function •
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Screening and habit breaking appliances, serial extraction, activators, etc.
Improvement of the skeletal relationship •
Fixed appliances.
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Management in permanent dentition • •
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Multi-attachment, fixed mechanotherapy Screening appliances with active extrusive force on incisors (tongue crib with active labial bow) Repelling and attracting magnets Functional appliances can play only subordinate role- used in the retention phase to prevent over eruption in the posterior segments
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BREIF DISCUSSION OF VARIOUS TREATMENT MODALITIES OF OPEN BITE www.indiandentalacademy.com
Management of open bite can be majorly classified as: 1 ORTHODONTIC HABIT BREAKING APPL.
2
ORTHOPEDIC
MYOFUNCTIONAL
3
SURGICAL
FIXED THERAPY
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ORTHODONTIC CORRECTION HABIT BREAKING APPLIANCES
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Tongue crib • Anterior open bite • A removal or fixed appliance can inhibit tongue thrust. The crib used with a removable appliance for an anterior open bite consists of a palatal plate with a horseshoe-shaped wire crib. •
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The crib is placed in the area of local tongue dysfunction and resultant malocclusion. www.indiandentalacademy.com
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Crib placed 3 to 4 mm lingual to upper incisors & it is made of 0.8mm wire If the crib is placed at the gingival third, a proper adjustment can stimulate the eruption of these teeth, a movement needed in open bite problems. It should neither touch the teeth nor disturb the www.indiandentalacademy.com occlusion.
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The acrylic also can be interposed between the teeth, covering the occlusal surfaces of the upper molars, to prevent eruption of these teeth and enhance anchorage of the plate, which is especially beneficial in open-bite problems. www.indiandentalacademy.com
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The bite-block here can be 3 to 4 mm, which is usually beyond the postural vertical dimension in open-bite patients. In such cases a stretch reflex is elicited from the closing muscles that enhances the depressing action on the buccal segments and helps close the anterior open bite. It can also incorporate an expansion screw, since many open bite problems also have a narrow arch. Thus the appl. combines inhibitory action via the screen & mechanical action via the jackscrew, labial bow, etc. www.indiandentalacademy.com
Posterior open bite • The crib is placed 2-3 mm away from the teeth & extends below the occlusal surface sufficiently to prevent tongue from inserting into the interocclusal space during rest position. • Fixed tongue cribs are also used
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Vestibular screen •
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An acrylic shield extending vertically from the upper labial fold to the lower labial fold and horizontally from the distal margin of the last erupted molar on one side to that on the other Edge to edge bite registered Worn at night and 2 to 3 hours during daytime Lip exercises along with the appliance
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Properly made and worn, the appl. is effective in eliminating abnormal sucking habits and lip dysfunction. It helps to establish a proper lip seal & indirectly influences the posture of the tongue. •
Modifications •
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Vestibular screen with breathing holes (mouth breathing pts. who have difficulty sleeping with the appl.) Vestibular screen with tongue crib
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Reminder appliances • An acrylic plate in which a bead or a wire mesh is embedded • Reminds the patient not to go back to the habit Other methods • Psychological approach • Parent counseling • Patient counseling and motivation • Dunlop’s Beta hypothesis • Chemical approach • Bitter tasting or foul smelling preparation placed on the thumb or digit •
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MYOFUNCTIONAL APPLIANCE
Activator •
The bite is opened 4 to 5 mm to develop a sufficient elastic depressing force and load the molar that are in premature contact.
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Properly constructed activators that follow this principle can influence the vertical growth pattern.
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To “close the V” between upper and lower dental arches by depressing the posterior maxillary segments with the activator in a manner analogous to that of orthognathic surgery
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Extrusion of incisors achieved by loading the lingual surfaces above the area of greatest concavity and also with the labial bow above the area of greatest convexity.
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A modification, the Elastic Activator similar to Stockfish’s kinetor was used in the treatment of anterior open bite by A. Stellzig et.al in 1999. • The intermaxillary acrylic of the lateral occlusive zones is replaced by elastic rubber tubes • Intrusion of both upper and lower posterior teeth by orthopedic gymnastics
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Bionator •
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The open bite Bionator used to inhibit abnormal posture and function of the tongue. The construction bite is as low as possible, but a slight opening allows the interposition of posterior acrylic bite blocks for the posterior teeth, to prevent their extrusion. To inhibit tongue movements, the acrylic portion of the lower lingual part extends into the upper incisor region as a lingual shield, closing the anterior space without touching the upper teeth. The palatal bar has the same configuration as the standard bionator. www.indiandentalacademy.com
Standard Bionator
Open bite Bionator
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The labial bow differs from the standard appliance, that the wire runs approximately between the incisal edges of the upper and lower incisors.
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The labial part of the bow is placed at the height of correct lip closure thus stimulating, the lips to achieve a competent seal and relationship.
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The vertical strain on the lips tends to encourage the extrusive movement of the incisors, after eliminating the adverse tongue pressures.
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Frankel Function Regulator . FR IV is used in
correction of open bite. It has two buccal shields, two lower lip guards, an upper labial wire, and four occlusal rests.
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Normally, anterior open bite problems show protracted tongue posture with incompetence of lips. The tongue tooth contact replaces the lip seal during deglutition to create negative atmospheric pressure.
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FR IV along with lip exercises (the anterior vertical muscle chain being strengthened by lip seal exercises) cause lips contact, reducing tongue protrusion and cause the tongue to move back into its normally raised position in proximity with palate, during deglutition.
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Incisors can then erupt normally to close the bite while the tongue reestablishes an interocclusal clearance between the posterior teeth. This allows the mandible to close upward & forward into a more favorable growth direction, reducing the MP angle. Modifications: • FR-IV with chin cap. • FR-IV with a tongue crib.
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Twin block •
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The appl. is modified to achieve vertical control & close the ant. open bite. The lower appl. extends distally to the lower molar region with clasps on the first molars & occlusal rests on the second molar to prevent their eruption. The acrylic slightly relieve contact with the lingual surfaces of U/L ant. teeth so that they are free erupt. A palatal spinner may be added to the upper appl. to help control an anterior tongue thrust.
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The bite is designed to register a 4mm interincisal clearance . It is necessary to accommodate blocks of sufficient thickness, to make it difficult for the pt to disengage the blocks. • Modifications • Headgear tubes can be attached and high pull traction can be applied to a modified face bow (concorde) for intrusion of molars • Vertical elastics (Dr Christine Mills) • Repelling or attracting rare earth magnets (Dellinger) www.indiandentalacademy.com
Headgears Centers of resistance in midfacial complex. 1. Alveolar process. 2. Maxilla.
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Direction of force passes behind both alveolar and skeletal centers of resistance, producing clockwise rotation of maxilla and maxillary dentition.
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Direction of force passes between alveolar and skeletal centers of resistance, producing clockwise rotation of maxilla and counterclockwise rotation of maxillary dentition.
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Direction of force passes above both alveolar and skeletal centers of resistance, producing counterclockwise rotation of maxilla and maxillary dentition.
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High pull HG •
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One approach to vertical excess problems is to maintain the vertical position of the maxilla & inhibit eruption of the max. posterior teeth – attempted by high pull HG. Worn 14 hrs a day with a force greater than 12 ounces/side. But this is least effective as it does not control the eruption of other teeth.
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High pull HG to a max. splint •
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A more effective HG approach for children with excessive vertical development. But still does not control the eruption of the lower teeth.
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High pull HG to a functional appl. with bite blocks •
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The most effective approach to growth modification involving vertical excess & a cl-II relation. The high pull HG improves retention of the functional appl. & produces a force direction near the estimated Cres. Of the maxilla If the bite block separates the teeth more than the free way space, a force is created against both U&L teeth that opposes eruption. www.indiandentalacademy.com
Lloyd E Pearson Describes seven different procedures for treatment of open bite with backward rotating mandible
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Procedure - I •
In the mixed dentition open-bite patient we could intrude the upper first permanent molars and then remove the remaining deciduous teeth, permitting open-bite closure.
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Occipital headgear with a transpalatal arch to control the inclination of the molars as they are intruded.
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After the molars have been intruded perhaps 3 mm the deciduous teeth are removed, the mandible is hinged closed, and the anterior open-bite is closed. www.indiandentalacademy.com
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The lower molars will often tend to extrude in this type of situation, unless mechanics are designed to control their eruption.
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An addition of a vertical pull-chin cup to the occipital headgear and transpalatal arch would intrude the upper molars, while preventing the eruption of the lower molars.
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As the open bite closes the mandible hinges upward, reducing the height of the lower face.
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Vertical pull chin cup
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Procedure -- II •
Extraction of first premolars and use a vertical pullchin cup with (16 ounces of forces)
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This can close the mandibular plane angle, reduce the lower facial height and close anterior open bites.
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Approximately 40 of closure of the mandibular plane angle was found in his study.
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Four possible mechanisms of (action at work) 1.
maxillary sutures are pressure sensitive and some intrusion of the maxilla could occur.
2.
The posterior teeth tend to move forward mesially.
3.
A slight change in the shape of the condylar neck, with many tending to be curved more forward than previously.
4.
A retardation of eruption of the posterior teeth. www.indiandentalacademy.com
Procedure -- III •
Mandibular bite- block therapy, augmented with vertical pull-chin cup therapy, can produce a favorable holding of the vertical height throughout the growth period, intrusion of posterior teeth
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The hinging of the mandibular plane in a counterclockwise direction and closure of anterior open bites.
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Procedure -- IV •
Magnetic bite blocks.
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Although we get rapid results, two difficulties arise with bite blocks a.
b.
Extreme mouth opening and patience to tolerate the appliance. lateral movement of the mandible, that can cause some temporomandibualr joint strain.
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Procedure -- V
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Occipital headgear has proved useful and generally seems effective in controlling the vertical dimension in the maxilla.
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Mandibular control appears to be more difficult to manage. www.indiandentalacademy.com
Procedure -- VI •
Another useful treatment modality is vertical reduction genioplasty.
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One advantage, is that it does not involve the temporomandibualr joints.
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It can be done after non-surgical treatment as an adjunct to bring the chin up and forward, to improve facial balance, and to achieve competency
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A vertical reduction genioplasty might be more useful in patients with the correct amount of exposed gingiva in the maxilla because it does not provide maxillary anterior intrusion.
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Procedure -- VII •
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Maxillary impaction + vertical reduction genioplasty, should also be considered. This can be a great benefit to patients with i. ii. iii. iv. v.
elongated upper posterior teeth, elongated upper anterior teeth, a gummy simile, a tall lower face, anterior maxilla with a maxillary impaction.
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Fixed Mechanotherapy 1.
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Extrusion of U & L incisors This treatment strategy is appropriate if the pt has an open bite with normal skeletal pattern Different methods of extrusion a) Extrusion arches - used in noncompliant pt. b) Vertical elastics - used in compliant pts
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a)
Extrusion arches
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Used to correct U & L occlusal planes that diverge ant. to the first PM.
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Indications : a) when spontaneous correction of an ant. open bite does not occur following tongue crib therapy b) when a constant extrusive force is desired in the ant. teeth with minimal post. side effects
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It is one-couple force system .
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Wire used is
16 x 22 SS or 17 X25 TMA with 900 offset bend at the molar. Extrusive force of 100 gms for 4 incisors.
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Mode of Action •
At the Incisor: Extrusion can involve single teeth or group of teeth.
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When a group of teeth are to be extruded ,a segment of heavy arch wire may be used in the brackets of the anterior teeth, and the teeth are extruded as if they were one big tooth.
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Whether the extrusion arch is tied segmentally or to continuous arch wire or placed directly into the brackets, the effect is the same www.indiandentalacademy.com
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At the Molar: • Intrusive force & a tip forward moment. • Relatively very minimal buccal flaring of the molar is seen.
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Proximal view
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1.
2.
3.
To negate the tip forward moment of the molar : Buccal segment from the upper first M to the first PM is added. The magnitude of the extrusive force should be kept low. Adding vertical elastics off the post. segment .
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b) i. •
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Vertical Elastics Triangle Elastics: Triangle elastics aid in the improvement of class I cuspid intercuspation and increasing the overbite relationship anteriorly by closing open bites in the range of 0.5 to 1.5 mm. They extend from the upper cuspid to the lower cuspid and first bicuspid teeth.
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ii.
Anterior Vertical Elastics: Class II orientation
Class III orientation
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Avoid Intermaxillary Elastics 1.
2.
3.
Intermaxillary elastics from the posterior teeth have a vertical force vector which extrudes these teeth and can further open the posterior vertical dimension. If class II or III elastics are required, they should be attached posteriorly to premolars rather than molars. These ‘short elastics’ minimize the extrusive effect on the back of the arch. www.indiandentalacademy.com
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2.
Bracket Position
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The placement point for incisor brackets may vary in cases of infraocclusion.
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In cases of open bite, placing anterior bracket 1 mm more towards the gingival side.
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3.
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Multiloop Edgewise Arch Wire (MEAW) In order to accomplish correction of a malocclusion, the dentition must be placed in a proper 3-dimensional perspective; AP, vertically, & bilaterally. AP – the axial inclinations of all teeth must be correct. In open bite cases, the inclination is characteristically mesial. The greater the openness of the occulsal planes, the greater the inclination.
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Multiloop Edgewise Arch Wire was developed by Kim to achieve these goals :i
ii.
iii.
Correcting the inclination of the occlusal planes. Aligning the maxillary incisors relative to the lip line. Uprighting the axial inclinations of the posterior teeth.
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The MEAW contains horizontal and vertical loops fabricated from a 16 x 22 ss wire in an L - shape fashion
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The vertical loops act as a break between the teeth, lowers the load deflection rate and provides horizontal control.
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The horizontal loops further reduces the load deflection rate and provides vertical control.
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Typical tip back bends of 3-5degrees are given on each tooth.
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Elastics are placed between the loops that lie mesial to opposing cuspids.
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Recommended elastic size is 3/16 inch heavy, with a force approximately 50 gms when the jaw is closed, & 150gms at moderate opening.
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The dentition must first be prepared for the use of this mechanism by elimination all rotations, spaces, crowding, or poorly positioned brackets.
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Prepared upper MEAW wire has a deep curve of spee & a lower a reverse curve. This wires will apply an intrusive force on the incisors, which would have the effect of worsening an openbite. This effect must therefore be counteracted by an anterior vertical elastic force
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KIMS technique was later modified by AYHAN ENACAR etal, using 16 x 22 reverse curve NiTi arch wires with heavy intermaxillary elastics applied in the canine region
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4.The Tip-edge Technique •
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Kesling in 1986 designed the Tip-edge brackets which are dynamic and upright teeth easily and automatically with or without intermaxillary elastics. No loops are required for uprighting. Anteriorly placed class II elastics along small anchor bends in the arch wire with Tip-edge brackets were used to correct anterior open-bite. Kim’s philosophy + Tip-edge brackets produced stable results in a very short period of time. www.indiandentalacademy.com
5. Extraction Of Teeth •
The various extraction modalities for the correction of an open bite are tailored towards:
a) b)
Extruding the ant. Segment Moving the post. teeth anteriorly (wedge effect.
c)
Combination of the two.
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Second Molar extraction •
Indicated in pts who have an open bite with contact only on these teeth & divergent occlusal plane.
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This method provides an advantage over the other extractions , since no space closure is needed & vertical forces are not likely to be generated.
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First Molar extraction •
If the second M have not erupted, & if the pt is only contacting on the first M would eliminate the increased vertical height and second M would only be erupted up to the new established vertical height. ( A Kuhlberg, 2003 )
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Extraction of PM •
This treatment works very well in pts with occlusal planes that diverge anteriorly from the PM.
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Bite is closed with help of extrusion of the ant. segment instead of the wedge effect.
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6. Low transpalatal arch •
It is believed that, tongue pressure against the transpalatal arch during swallowing, especially when the transpalatal arch is placed low in the palate, will inhibit maxillary alveolar vertical growth.
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7.Low Mandibular Lip Bumper •
Cetlin and Hoeve advocated the use of a lip bumper for the development of the lower dental arch.
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They suggested that if the lip bumper were adjusted low, the cheek and lip mucosa would rest above the appliance, and this will inhibit vertical mandibular molar dentoalveolar development.
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8. ACTIVE VERTICAL CORRECTOR •
AVC is a simple removable or fixed orthodontic appliance that intrudes the posterior teeth of both the maxilla and mandible by reciprocal forces.
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By effective intrusion of posterior teeth, the mandible is allowed to rotate in upward and forward directions.
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The uniqueness of this appliance is that, it corrects anterior open bite problems by actually reducing anterior facial height.
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Problems formerly thought to require orthognathic surgery, can now be treated successfully with AVC.
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Method of Action :•
Force system -- generated by repelling magnets,
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AVC is considered superior to a static bite block appliance energized only by the intermittent force from the muscles of mastication.
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The constant force system of the AVC results in greater rapidity of tooth movement. www.indiandentalacademy.com
9. Skeletal Anchorage System (SAS) • •
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Skeletal anchorage system was developed for tooth movements. Mikako Umemori et al. in 1999 described the SAS (Skeletal Anchorage System for open bite correction). SAS consists of titanium miniplates (SMAP- Super Mini Anchor Plate Dentsply-sankin ) that are temporarily implanted in the maxilla or the mandible as an immobile anchorage. These miniplates are fixed at the buccal cortical bone around the apical regions of the lower first and second molars on both the sides. www.indiandentalacademy.com
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Advantages of SAS : No serious side effects. Simplified treatment mechanics. Shortened treatment period. Minimum discomfort. Control of the level of occlusal plane.
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SURGICAL CORRECTION •
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Hulliten in 1849, was the first to surgically correct an ant. open bite.( Ant. Mand. Sub-apical Osteotomy ). Cohn-stock in 1921, introduced Ant. Max. Osteotomy which was modified by Wassmund, Wunderer & Cupor. Schuchardt introduced Post. Max. Osteotomy as a two-stage procedure which was modified to a singlestage procedure by Kufner.
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Limberg in 1925, introduced Closed Sub-condylar & Open oblique Osteotomy. The present-day surgical techniques to correct open bite involves, Max. surgery for ant. extrusion & post. intrusion, and Mand. surgery to elevate the incisor segment. The choice of the appropriate surgical technique requires careful diagnostic evaluation
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ANTERIOR MAX. & MAND. SUB-APICAL OSTEOTOMY •
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INDICATIONS FOR MAXILLARY ASO A small open bite with minimal tooth exposure, lip incompetance , good naso-labial angle & adequate lower ant.facial height. An unaesthetic edentulous appearance due to concealed maxillary incisors
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INDICATIONS FOR MAND. ASO •
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Ant. open bite due to reverse curve in the mandibular arch. Transverse max.-mand. harmony & good aesthetic balance between upper lip & max. ant. teeth. After surgery the max. & mand. Ant. Segment are immobilised for 5-6 weeks. Relapse potential is very minimal.
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• • • •
KOLE MODIFICATION OF SUB-APICAL OSTEOTOMY Indications: Mandibular prognathism with ant. open bite. Severe reverse curve. Excessive chin height. Functional post. occlusion. Satisfactory lip-tooth relationship & no transverse deficiency in maxilla. The principle disadvantage here relates unpredictable soft tissue profile changes & chin height changes. www.indiandentalacademy.com
Sagittal Split Ramus Osteotomy •
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This surgery can be performed in both extraction & non-extraction cases. It is indicated in open-bite cases with severe mand. deficiency or prognathism. It is usually done along with maxillary osteotomy to minimize relapse. If performed separately, posterior overcorrection with an interocclusal splint, supra-hyoid myotomy and cervical collar should be considered to prevent relapse www.indiandentalacademy.com
Le Fort-I Maxillary Osteotomy • • • •
This surgery is indicated in open-bite cases with: High & constricted palatal vault. Lip incompetence. High mand. plane angle. Increased distance between the palatal root apices & the nasal floor.
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•
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If the inferior turbinates are interfering with the repositioning of the maxilla, they are trimed with a Mayo scissors (Adjunctive Inferior Turbinectomy ). Stabilization of the maxilla is done with trans-osseous 26-guage wire sutures. If there are bony defects after surgery, bone grafts from the Iliac crest or Hyroxyapatite crystals are used to bridge them.
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GENIOPLASTY
1. 2. 3. 4. 5.
Fridrich et al. in 1997 described various Genioplasty stratergies for anterior facial vertical dysplasias. Different types of Genioplasty: Sliding advancement genioplasty Genioplasty with parallel ostectomy Genioplasty with down graft Genioplasty with anteriorly tapered ostectomy Sliding setback genioplasty www.indiandentalacademy.com
RETENTION & RELAPSE • •
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The main etiological factors responsible for relapse after orthodontic correction are: Latent vertical growth of the face. The role of the tongue. The main etiological factors responsible for relapse after surgical correction are: Mandibular musculature Incompletely understood biomechanical factors influencing the Elevator group & Suprahyoid group of muscles. www.indiandentalacademy.com
The success of treatment depends upon the ratio: Magnitude of improvement Success = Magnitude of relapse Wick Alexander stated that retention begins with Diagnosis & Treatment planning. ‘Begin with the end in mind’ should be the philosophy of treatment. www.indiandentalacademy.com
RETENTION AFTER ORTHODONTIC CORRECTION : Criteria to begin retention are : 1. Coincidence of Centric relation & occlusion. 2. Class I cuspid relation. 3. Maintenance of mand. cuspid width. 4. Interincisal angle close to normal. 5. Normal ant. Overbite & Overjet. 6. Normal Buccal Overjet.
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7. 8. 9. 10.
Levelled max. & mand. arches. All spaces closed & all rotations eliminated. Roots parallel near extraction sites. Posterior cusps may or may not be settled.
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1.
2. 3.
Active retention normally utilizes : A maxillary wraparound retainer and a mandibular 3x3 bonded retainer. A full coverage clear acrylic appliance. In conjunction with myofunctional therapy, tongue position exercises are advocated.
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John Sheridan in 1997, described the Force Amplified System for corrected open-bite. It involves a) The use of conventional max. & mand. cuspid to cuspid bonded lingual retainers, b) Low-profile bonded lingual Caplin hooks and c) Intraoral elastics. The retainers are bond to each tooth to distribute the elastic forces.
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RETENTION AFTER SURGICAL CORRECTION : 1. 2. 3.
4.
Upper & lower border wiring of the mandible. Steinmann pins to stabilize the maxilla. Skeletal wire fixation (Circumzygomatic & Circummandibular wires). Rigid fixation.
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conclusion The treatment of open bite still remains a challenge to the clinician, and careful diagnosis and timely intervention will improve the success of treating this malocclusion.
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