Development and diagnosis of deepbite

Development and Diagnosis of Deep bite.

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Introduction:

Malocclusion is a developmental condition. In most

instances, malocclusion and dentofacial deformity are

caused, not by some pathologic process, but by moderate

distortions of normal development. More often these

problems from a complex interaction among multiple

factors that influence growth and development, and it is

impossible to describe a specific etiologic factor.


The term “overbite” applies to the distance which the

maxillary incisal margin closes vertically past the

mandibular incisal margin, when the teeth are brought into

habitual or centric occlusion.

The term “closed bite” or “deepbite” describes a

condition of excessive overbite, where the vertical

measurement between the maxillary and mandibular

incisal margins is excessive when the mandible is brought

into habitual or centric occlusion.


Types of Deepbite.Based on etiology

• Developmental deepbite and

• Acquired deepbite.

Two types of developmental or genetically determined :

1. Skeletal deepbite: due to horizontal growth pattern and is a common malocclusion.

2. Dentoalveolar deepbite: caused by supraocclusion of the incisors, also is common. Interocclusal clearance is usually small, i.e. overbite is functionally a pseudo-deep overbite. www.indiandentalacademy.com

An acquired deep overbite may be caused by:

1. A lateral tongue thrust or postural position produces an infraocclusion of the posterior teeth, which in turn leads to a deep overbite. The freeway space is usually-large.

Eg: classic Class II, division 2 malocclusion.

2. Premature loss of deciduous molars or early loss of per manent posterior teeth, particularly if the contiguous teeth are tipped into the extraction sites.

3. The wearing away of the occlusal surface or tooth abrasion.


Etiology:Role of muscles in functional movements:

The mandible is the only movable bone in the head and face.

It can only be moved in certain directions (limitations of morphology and structure TMJ)

The postural function must be effective enough to permit the muscle activity associated specifically with mastication, deglutition, respiration and speech. Thus, a number of functions are superimposed on the primary and postural function.


1. Anterior and posterior fibers of temporalis;

2. Lateral pterygoid;

3. Anterior, middle and posterior components of masseter;

4. Suprahyoid;

5, Infrahyoid. - Medial pterygoid not shown.

Muscles primarily responsible for mandibular movements:


Opening movement:

• Gravity and contraction of the lateral pterygoid muscles.

• The temporal, masseter and medial pterygoid muscles show a controlled relaxation as the mandible opens (serves to make the opening movement smooth.)

• Articular disk is brought forward by the lateral pterygoid muscle and intimately related capsular ligaments as the condyle rotates against the inferior surface of the disk and as the disk itself glides forward on the articular eminence.


Closing movement:

• More power is elicited due to bilateral activity of the masseter and temporalis muscles, assisted by the smaller medial pterygoid muscles.

• While mastication may call for the most potent effort from the associated muscles, Such complex activity naturally brings into function associated muscle elements, and this makes an analysis of the role of any individual muscle quite difficult.


Drawing to show normal muscle activity associated with normal jaw relationship and normal occlusion. Electromyographic recordings would show even distribution of anterior, middle and posterior temporalis and deep and superficial fiber activity.

LAT. PTERYGOIDMED. PTERYGOID


• A good motto for the cranial, facial, masticatory, suprahyoid and infrahyoid muscles plus the prevertebral and postvertebral muscles is "team work."

• This team work means that adjusting or compensatory muscle activity is available as the functional demands vary.

• This also means that where there is a malocclusion or abnormal morphologic relationship, certain compensatory or adaptive muscle functions may arise, either to restrain the dental malocclusion or to actually increase the discrepancy.


A small change in any of the variables affecting the temperomandibular joint (TMJ) may cause pathology.

Eg: lack of harmony of postural vertical dimension (PVD) and occlusal vertical dimension (OVD), with mandibular overclosure.

Excessive interocclusal space and overclosure, or "deep bite," may change this harmonious, stabilizing, balancing and smooth action.


Where there is a Class II malocclusion, mandibular retrusion and excessive apical base difference, middle and posterior temporalis and deep masseter fibers show greater magnitude of contraction. exerting a posterior thrust on the mandibular condyle (and disk). This adapts to and enhances the mandibular retrusion.


In forced retrusion, electromyographic records show a dominance of

• posterior temporalis,

• posterior masseter and

• Posterior suprahyoid muscles.


With Class II malocclusion and deep overbite, the functional retrusion tendency is increased. In addition to dominance and posterior and deep masseter activity, stretch reflex and subsequent muscle contractions or spasms may be elicited for the lateral pterygoid fibers which insert into the articular disk. This serves to pull the disk forward as the condyle is functionally retruded (see arrow). Condyle may then impinge on retrodiscal pad.

DIAGASTRICGENIOHYOID


While the lateral pterygoid muscle serves as the protractor for the disk, moving it forward by virtue of insertion of fibers into the capsule and disk, only the retrodiscal tissue and capsule, and integrity of the ligaments serve to retract the disk.

There is no articular disk retracting muscle. In other words, the lateral pterygoid has no opposing stabilizing and antagonistic muscle force, as far as the disk is concerned.


Resistance to posterior condylar displacement by the lateral pterygoid muscles (2) is apparently insufficient, since primary function is that of opening, not closing, and secondary stabilizing assignment on closure can result in excessive forward movement of the articular disk on maximum contraction.


Tracing of lateral cephalogram showing:

1. open mouth position;

2. postural resting position;

3. premature initial contact;

4. retruded occlusal position.

Tooth guidance from point of premature initial contact has changed the path of closure from upward and forward to upward and backward.


• The condyle, riding over the posterior periphery of the disk, produces a discernible click, and then impinges on the postarticular connective tissue.

• The postarticular tissue is supplied by nerve fibers from the auriculotemporal nerve and is less adapted to stresses of mandibular function.

• Joint structures may adapt to deviate activity for a time, but with constant stimulation of stretch reflex, forward pull of the disk, impingement on postarticular connective tissue, muscle spasm and .overclosure, these structures may not continue to adapt indefinitely.


• Irritation and lack of harmony of the structures is clinically observed in the form of clicking and crepitus.

• Pain can be caused either by impingement on retrodiscal tissues, or by pterygoid spasm (MPD).

• Whatever the sequence of events, there is broad agreement on the lack of harmony of condyle, disk and eminence during the opening and closing movements.


Effects of growth pattern:

Rotation of Jaws during Growth:

Until longitudinal studies of growth using metallic implants in the jaws (1960s, Bjork and coworkers in Copenhagen), the extent to which both the maxilla and mandible rotate during growth was not appreciated.

The reason is that the rotation that occurs in the core of each jaw, called internal rotation, tends to be masked by surface changes and alterations in the rate of tooth eruption. The surface changes produce external rotation.


The core of the mandible is the bone that surrounds the inferior alveolar nerve.

The functional processes include the alveolar process (bone supporting the teeth and providing for mastication), the muscular processes (the bone to which the muscles of mastication attach), and the condylar process, the function in this case being the articulation of the jaw with the skull.


If implants are placed in areas of stable bone away from the functional processes, it can be observed that in most individuals, the core of the mandible rotates during growth in a way that would tend to decrease the mandibular plane angle (i.e., up anteriorly and down posteriorly).


Terminology, rotational changes.

Condition Bjork Shudy

Ant. Growth > post.Post. Growth > ant.

Forward rotationBackward rotation

Clockwise rotationCounterclockwise rotation

Bjork Solow, Houston Proffit

Rotation of mandibular core relative to cranial base

Total rotation True rotation Internal rotation.

Rotation of mandibular plane relative to cranial base

Matrix rotation Apparent rotation Total rotation

Rotation of mandibular plane relative to the core of mand.

Intramatrix rotation Angular remodeling of the lower border

External rotation


• Internal rotation of the mandible varies between individuals, ranging up to 10 to 15 degrees.

• For an average individual with normal vertical facial proportions, however, there is about a -15 degree internal rotation from age 4 to adult life. (25% - matrix rotation and 75% - intramatrix rotation.)

• During the time that the core of the mandible rotates forward an average of 15 degrees, the mandibular plane angle, representing the orientation of the jaw to an outside observer, decreases only 2 to 4 degrees on the average.


Reason that the internal rotation is not expressed in jaw orientation, of course, is that surface changes (external rotation) tend to compensate.

This means that the posterior part of the lower border of the mandible must be an area of resorption, while the anterior aspect of the lower border is unchanged or undergoes slight apposition.


Superimposition on implants for an individual with a normal pattern of growth, showing surface changes in the mandible from ages 4 to 20 years. For this patient there was -19 degrees internal rotation but only -3 degrees change in the mandibular plane angle. Note how the dramatic remodeling (external rotation) compensates for and conceals the extent of the internal rotation. (From Bjork A, Skieller V: Eur J Orthod 5:1-46, 1983.)


It is less easy to divide the maxilla into a core of bone and a series of functional processes. The alveolar process is certainly a functional process in the classic sense, but there are no areas of muscle attachment analogous to those of the mandible. The parts of the bone surrounding the air passages serve the function of respiration, and the form function relationships involved are poorly understood.

If implants are placed above the maxillary alveolar process, however, one can observe a core of the maxilla that undergoes a small and variable degree of rotation, forward or backward.


Superimposition on implants in the maxilla reveals that this patient experienced a small amount of backward internal rotation of the maxilla (i.e., down anteriorly). A small amount of forward rotation is the more usual pattern, but backward rotation occurs frequently. (From Bjork A, Skieller V: Am J Orthod 62:357,1972.)


Matrix rotation, as defined for the mandible, is not possible for the maxilla. At the same time that internal rotation of the maxilla is occurring, there also are varying degrees of resorption of bone on the nasal side and apposition of bone on the palatal side in the anterior and posterior parts of the palate.

For most patients, the external rotation is opposite in direction and equal in magnitude to the internal rotation, so that the two rotations cancel and the net change in jaw orientation (as evaluated by the palatal plane) is zero. Until the implant studies were done, rotation of the maxilla during normal growth had not been suspected.


Both internal and external rotation occur in everybody, but variations from the average pattern are common.

Greater or lesser degrees of both internal and external rotation often occur, altering the extent to which external changes compensate for the internal rotation.

The result is moderate variation in jaw orientation, even in individuals with normal facial proportions.

In addition, the rotational patterns of growth are quite different for individuals who have what are called the short face and long face types of vertical facial development.


Short anterior lower face height, have excessive forward rotation of the mandible during growth, resulting from both an increase in the normal internal rotation and a decrease in external compensation. The result is a nearly horizontal palatal plane and mandibular morphology of the "square jaw" type, with a low mandibular plane angle and a square gonial angle. A deep bite malocclusion and crowded incisors usually accompany this type of rotation. (From Bjork A, Skieller V:Am J Orthod 62:344,1972.)

Short face type,


The pattern of jaw rotation in an individual with the "long face" pattern of growth (cranial base superimposi tion). As the mandible rotates backward, anterior face height increases, there is a tendency toward anterior open bite, and the incisors are thrust forward relative to the mandible. (From Bjork A, Skieller V: EurJ Orthod 5:29, 1983.)

Long face type, who have excessive lower anterior face height, the palatal plane rotates down posteriorly, often creating a negative rather than the normal positive inclination to the true horizontal. The mandible shows an opposite, backward rotation, with an increase in the mandibular plane angle. The mandibular changes result primarily from a lack of the normal forward internal rotation or even a backward internal rota tion.


The internal rotation, in turn, is primarily matrix rotation (centered at the condyle), not intramatrix rotation.

This type of rotation is associated with anterior open bite malocclusion and mandibular deficiency (because the chin rotates back as well as down).

Backward rotation of the mandible also occurs in patients with abnormalities or pathologic changes affecting the temperomandibular joints. In these individuals, growth at the condyle is restricted.


Mutual relationship of the rotating jaw bases:

Dentoalveolar occlusion or malocclusion depends on the combination of these rotations. (Lavergne and Gasson (1982) in human implant studies)

1. Convergent rotation of the jaw bases - creates a severe, deep overbite that is difficult to manage using functional methods.

2. Divergent rotation of the jaw bases - cause marked open-bite problems. In severe cases, orthognathic surgery is required for correction


3. Cranial rotation of both bases—In this horizontal growth pattern a relatively harmonious rotation of both jaws occurs in an upward and forward direction. This rotation of the maxilla compensates for upward and forward mandibular rotation, offsetting a deep bite. The result is a normal overbite.

4. Caudal, or down and back, rotation of both bases — This rotation occurs in a relatively harmonious manner. The down and back maxillary rotation offsets the open bite created by down and back mandibular rotation.


Interaction between Jaw Rotation and Tooth Eruption:

Influences the magnitude of tooth eruption, direction of eruption and the ultimate anteroposterior position of the incisor teeth.

Movement of the teeth relative to the cranial base obviously could be produced by a combination of translocation as the tooth moved along with the jaw in which it was embedded and true eruption, movement of the tooth within its jaw..


Maxillary teeth: downward and somewhat forward. In normal growth, the maxilla usually rotates a few degrees forward but frequently rotates slightly backward.

Forward rotation would tend to tip the incisors forward, increasing their prominence, while backward rotation directs the anterior teeth more posteriorly than would have been the case without the rotation, relatively uprighting them and decreasing their prominence.


Superimposition on mandibular implants shows the lingual positioning of the mandibular incisors relative to the mandible that often accompanies forward rotation during growth. (FromBjorkA, SMeller V:AmJOrthod62:357, 1972.)

Mandibular teeth: upward and somewhat forward. The normal internal rotation of the mandible carries the jaw upward in front. This rotation alters the eruption path of the incisors, tending to direct them more posteriorly than would otherwise have been the case.


Because the internal jaw rotation tends to upright the incisors, the molars migrate farther mesially during growth than do the incisors, and this migration is reflected in the decrease in arch length that normally occurs.

When excessive rotation occurs in the short face type of development, the incisors tend to be carried into an overlapping position even if they erupt very little; hence the tendencies for deep bite malocclusion in short face individuals. The rotation also progressively uprights the incisors, displacing them lingually and causing a tendency toward crowding.


Cranial base superimpositon for a patient with the short face pattern of growth. As the mandible rotates upward and forward, the vertical overlap of the teeth tends to increase, creating a deep bite malocclusion. In addition, even though both the upper and lower teeth do move forward relative to cranial base, lingual displacement of incisors relative to the maxilla and mandible increases the tendency toward crowding. (From Bjork A, Steelier V: Am JOrthod62:355, 1972.)


In the long face growth pattern, on the other hand, an anterior open bite will develop as anterior face height increases unless the incisors erupt for an extreme distance. The rotation of the jaws also carries the incisors forward, creating dental protrusion.

Mandibular rotation is caused by both growth-dependent and functional influences. Functional orthodontic and orthopedic methods alter function and guide the growth process. For this reason the rotation of the mandible may be moderately influenced therapeutically.


Environmental influences such as neuromuscular dysfunction, occlusal forces, gravity and nasorespiratory malfunction (according to Linder, Lowe, and Woodside [1986]) can modify this inclination.


Three diagnostic exercises are recommended:

1. Determination of the postural rest position (mandible and interposed freeway space or interocclusal clearance).

2. Examination of temperomandibular joint (TMJ) function or dysfunction and condylar movement and

3. Assessment of the functional status of the lips, and tongue, with particular attention to the roles they play in dentofacial abnormalities

Diagnosis:


Determination of the Postural Rest Position and Interocclusal Clearance:

• A major determinant of adult shape is the functional pattern (originating from postural rest position of the mandible) - registration is a priority.

• Muscular components are in dynamic equilibrium and their balance is maintained with muscle tonus that responds only to the permanent exogenous force affecting the orofacial system (i.e., gravity).

• Rest position depends on and alters with the position of the head. Thus natural head position (NHP) must be determined for each patient.


The regimen for the examination is as follows:

1. Determination of the postural rest position with the head in NHP

2. Registration and measurement of the postural rest position

3. Evaluation of the relationship of rest position to occlusal position in the following dimensions:

• Sagittal

• Vertical

• Transversewww.indiandentalacademy.com

Assessment of the postural rest position:

The patient is seated upright, preferably with the back unsupported.

The head is oriented with the patient looking ahead at eye level. (mirror)

If this position seems too variable or the patient is not relaxed, the head can be positioned with the eye-ear plane (Frankfort) horizontal.


Several methods are available to determine the postural rest position of the mandible:

• Phonetic exercises

• Command methods

• Non-command methods

• Combined methods


Phonetic exercises.

Asked to repeat selected consonants.

The letter m is repeated 5 to 10 times. C also can be used.

Repeating or spelling the word Mississippi also is a good exer cise.

After the phonetic exercise the patient is instructed not to move the lips or tongue at this time, even while the dentist gently parts the lips to observe the interocclusal space and tongue position.

Less satisfactory for children. In the mixed dentition, language habits vary and are not yet stabilized.


Command methods.

Asked to perform selected functions; having the patient lick the lips and then swallow produces the desired relationship because the mandible returns to postural rest within 2 seconds after the exercise.

Non-command methods.

Patient has no idea of the parameter being examined. Careful observations are made as the patient talks, swallows, and turns the head while being questioned on a number of unrelated subjects.


Combined method.

Provides the best reproduction in the mixed dentition.

Asked to perform a prescribed function (e.g., swallowing, to lick the lips, swallow, and then hold still. ) and then relax.

After instructing the patient not to move, the clinician gently palpates the submental muscles to assess whether they are relaxed and parts the lips to observe the relationship of the canines.

Normally the lower canine should be 3 mm below the upper in comparison with the occlusal position. An interocclusal space of 4 mm may be normal.www.indiandentalacademy.com

Registration of the postural rest position of the mandible.

Various methods are recommended for producing the best record:

• Direct intraoral method

• Indirect extraoral method

• Direct extraoral method


Direct intraoral method.

• A plaster core registration similar to that sometimes used in prosthodontics.

• Measuring is difficult, although millimetric calipers can be used to record the interocclusal space in the canine or incisor area.

Indirect extraoral method.

The indirect extraoral method is the most common one used, and various techniques are available: roentgenography, cephalometry, electromyography, cinefluorography, and kinesiography


Direct extraoral method.

Direct caliper measurements can be made on the patient's profile by measuring the distance from soft tissue nasion (at the bridge of the nose) or point A to menton (on the lowest curvature of the chin).

Done in both postural rest and habitual occlusion.

The difference between the two measurements constitutes interocclusal clearance. (soft tissues reduce reliability and no record of the saggital relationship is produced.)


Evaluation of the path of closure from postural rest to occlusion in the saggital plane:

Condylar movement from postural rest to occlusion can consist of pure hinge movement, hinge and anterior translatory displacement, and hinge and posterior superior translatory displacement.

In Class II malocclusions without functional disturbance the path of closure from rest to occlusion is straight up and forward, with a hinge movement of the condyle in the fossa. These are true Class II malocclusions.


In Class II malocclusions with functional disturbances (deepbite) a rotary action of the condyle in the fossa from postural rest to occlusion is evident.

From initial contact to full occlusion, condylar action is both rotary and translatory up and backward (posterior shift). Thus the movement combines rotary and sliding components

Posterior translation or sliding into the occlusal position in an abnormal functional pattern with a deviated path of closure.


Evaluation of the path of closure from postural rest to habitual occlusion in the vertical plane:

This evaluation is of special interest in the assessment of deep overbite cases. Two types of deep overbite can be differentiated.

True deep overbite with a large interocclusal clearance is caused by infraocclusion of the posterior segments. (lateral tongue posture or tongue thrust habit.)Eg: Class II, division 2 malocclusions.


Pseudo-deepbite with a small interocclusal space already has normal eruption of the posterior segment teeth.

The deep overbite is combined with overeruption of the incisors.

Eg: Class II, division 2 malocclusions that produce a "gummy" smile and poor lip line relation.

The amount of interocclusal clearance is a distinguishing criterion.


Examination of the Temperomandibular Joint and Condylar Movement:

The objective is to assess whether incipient symptoms of TMJ dysfunction are present.

• Clicking and crepitus

• Sensitivity in the condylar region and masticatory muscles

• Functional disturbances (e.g., hypermobility, limitation of movement, deviation)

• Radiographic evidence of morphologic and positional abnormalities


Clicking is seldom noted at the initial examination.

Crepitus can sometimes be observed during the opening movement (initial, intermediate, or terminal).

Terminal clicking or crepitation - hypermobility or too-wide opening. Sign of peripheral irregularity of the articular disk or unevenness of the condylar surface; this type of crepitus is amenable to correction. Crepitation during chewing is occasionally seen, especially in children with deep overbites.

Deviation was most frequently accompanied by crepitus or clicking.


Tenderness to palpation in the condylar region is the most characteristic symptom of initial functional disturbance of the TMJ. The palpatory tenderness of the temporalis and masseter muscles.

The lateral pterygoid muscle (LPM) is probably implicated.

Hypermobility: an opening of more than 45 mm in 6 to 8year) old children and more than 49 mm in 10 to 12-year old children.

The problem is mostly habitual, but it can indicate a disposition to later temperomandibular dysfunction (TMD).


Neuromuscular involvement in TMJ problems was also observed in the lip and tongue areas.

In children without TMJ dysfunction, 20.5% of the sample showed abnormal perioral activity; the percentages were significantly higher in children with TMJ symptoms (43 %).

Tongue dysfunction was seen in 12.4% of the sample without TMJ problems, compared with 21% in the TMJ problem group.


Clinical functional examination for the temperomandibular joint area:

• Auscultation

• Palpation

• Functional analysis


Auscultation:

A stethoscope is used to check for signs of clicking and crepitus. The examinations are performed by having the patient open and close the jaw into full occlusion.

If clicking or crepitus is noted, the patient is instructed to bite forward into incision and then repeat the opening and closing movements. These movements are checked for any sounds with the stethoscope. Most often, sounds disappear in the protruded position.


Palpation.

• The condyle and fossa are palpated with the index finger during opening and closing maneuvers.

The posterior surface can be palpated by inserting the little finger in the external auditory meatus and can be checked for tenderness, synchrony of action, and coordination of relative position in the fossae.

• In TMJ patients, palpation of the muscles of the face, head, and neck is essential.

Tenderness in the superior head of the LPM is an important diagnostic clue because it may indicate abnormal functional loading of the joint.


Palpation of LPM. can be approximated by placing the forefinger behind the maxillary tuberosity, right above the occlusal plane, with the palmar surface of the finger directed medially toward the pterygoid hamulus

In patients with early TMJ symptoms, unilateral tenderness commonly occurs. If hypersensitivity or pain is present on both sides, palpation of other associated muscles is indicated.


Functional analysis.

Dislocation of the condyles and discoordination of movements are early symptoms of functional disturbance.

Functional movements of the mandible and condyles are carefully assessed.

The extent of maximum opening is measured between the upper and lower incisors with a Boley gauge. In overbite - added to the measurement, whereas in open bite - must be subtracted.

The direction of opening and closing movements should be registered graphically with curves. Premature contacts and deviations in sagittal and transverse directions are assessed.www.indiandentalacademy.com

Characteristic findings of Deepbite:

Dentoalveolar Deep Overbite:

The growth pattern usually is average or tends toward the vertical. The deep overbite caused by the infraocclusion of molars has the following symptoms:

1. The molars are partially erupted.

2. The interocclusal space is large.

3. A lateral tongue posture and thrust are present.

4. The distances between the maxillary and mandibular basal planes and occlusal plane are short.


The deep overbite caused by over eruption of the incisors has the following characteristics:

1. The incisal margins of the incisors extend beyond the functional occlusal plane.

2. The molars are fully erupted.

3. The curve of Spee (compensating curve) is excessive.

4. The interocclusal space is small.


Skeletal Deep Overbite

• Horizontal type of growth pattern.

• The AFH is short, particularly the lower facial third, whereas the posterior facial height is long.

• Ratio of U/L anterior facial height is reduced in the skeletal deep overbite to a ratio of 2:2.5 or 2:2.8 (normal- 2:3).

• The horizontal cephalometric planes (sella-nasion, palatal, occlusal, and mandibular) are approximately parallel to each other.


• The interocclusal clearance is usually small.

• An extreme horizontal growth pattern can be at least partially compensated by an up and forward inclination of the maxillary base (anteinclination).

• On the other hand, the combination of a horizontal growth pattern with a down and forward inclination (retroclination) of the maxillary base results in a more severe skeletal deep overbite.


Conclusion:




Education

Development and diagnosis of deepbite