Section E OCCLUSAL THERAPY

Chapter 42}

OCCLUSAL THERAPY

Arnold S . Weisgold Harold S . Baumgarten Therapeutic occlusion Difficulties in occlusal therapy Form and function of the masticatory system Altered canine form Occlusal appliances Classification Use of sectorial appliances Use of full-coverage appliances Guidelines in the use of occlusal appliances Occlusal adjustment Retruded position Adjusting the existing occlusion Diseases related to pathologic occlusion Myofascial pain dysfunction syndrome Disorders of the condyle-disk assembly Conclusions Based on recent clinical research, certain features about trauma from occlusion, its relationship to infective

periodontal diseases, and its modes of therapy seem to agree in large measure with long-term clinical

observations. These characteristics of occlusal trauma can be listed as follows: 1. Both human and animal experiments demonstrate that trauma from occlusion does not cause pathologic

changes in the supraalveolar connective tissue or junctional epithelium. For example, several studies have

demonstrated that when "jiggling" force experiments are performed on animals with a normal periodontium,

the supraalveolar connective tissue is not influenced by the occlusal forces, even though changes do occur in

the periodontal ligament and alveolar process. 2. Once the periodontal space has increased in width to

/ compensate for occlusal forces, the ligament tissue will usually show no signs of increased vascularity or

exudation.' Mobility will no longer be progressive in nature. Therefore the clinician must distinguish between

increased mobility, which is greater than normal, and increasing mobility, which gets progressively worse

over time. 3. Trauma from occlusion can cause resorption of the alveolar bone. This resorption can be reversed by

eliminating or tempering the occlusal forces by means of occlusal adjustment. It has been demonstrated that

with removal of the forces causing the trauma, bone tissue is deposited along the walls of the alveolus and on

the bone crest,area. This results in narrowing of the increased periodontal space. Stated another way, when

tooth mobility be increased because of trauma, resulting in an increased width of the periodontal ligament,

occlusal adjustment is an effective mode of therapy to reduce tooth mobility. 4. With continuing plaque-associated infective periodontal disease, trauma from occlusion, under certain

circumstances, enhances the rate of progression of the disease. Recent findings appear to show, however, that

the progression of plaque-associated lesions seems to be unrelated to the width of the periodontal ligament

space. 5. Both a healthy periodontium with reduced height and a healthy periodontium with normal height appear to

react similarly in their adaptation to excessive occlusal forces. 6. In the presence of reduced alveolar bone height in a healthy periodontium with a normal width of the

periodontal ligament, tooth mobility can be accepted and splinting avoided if mastication is not impaired and

the patient is comfortable. 7. Splinting is an indicated mode of therapy when the alveolar bone height is so compromised that tooth

mobility 493 494 ANTIINFECTIVE AND ADJUNCTIVE MANAGEMENT OF PERIODONTAL DISEASES increases over time and mastication is impaired, or the patient is uncomfortable. There are many definitions for the term trauma from occlusion. There is general agreement that it signifies

pressure on the teeth capable of causing pathologic changes or adaptive alterations in the surrounding

periodontium. The lesions of primary and secondary occlusal trauma are the same; however, primary origins

of trauma may play a far more significant role in the pathologic changes because they are of greater intensity

and more sustained in nature. In treating patients with both infective periodontitis and trauma from occlusion, it is clear that initial therapy

should be directed primarily toward control of plaque-associated etiology. Elimination or reduction of

excessive occlusal forces may decrease tooth mobility but will not arrest the destruction of the periodontium

associated with periodontal infection. It is of paramount importance that tooth mobility be carefully

monitored over a reasonable period of time to determine whether it is increased and stable or progressively

increasing. THERAPEUTIC OCCLUSION Once the clinician decides that there are rational reasons for altering an existing occlusion, it is important to

outline the objectives of occlusal therapy to achieve a therapeutic occlusion that is consistent with health. The

occlusion resulting after therapy may not conform to our preconceived concept of an ideal occlusion and

often represents an acceptable compromise. The basic objectives of any form of occlusal therapy should be: 1. Establishment or maintenance of a stable, reproducible intercuspal position 2. Freedom of movement to and from the intercuspal position 3. Development of an occlusion not noticeable to the patient 4. Maintenance of the newly established occlusal scheme over a reasonable period of time 5. Establishment of an occlusion with acceptable pho-nation, mastication, and esthetics 1. Establishment or maintenance of a stable, reproducible, intercuspal position. The posterior teeth should

inter-cuspate in such a manner that forces will be directed along the long axes of the teeth. There is

disagreement as to where the mandible should be when the teeth intercuspate. The prevailing concepts

include the following: (1) all occlusal therapy should be done with the mandible in the intercuspal position;

(2) the teeth should be made to articulate in the retruded path of the mandible; (3) the teeth should articulate

in the retruded path, but allowance should be made for the mandible to move forward a certain distance to

another intercuspal relationship; and (4) only the initial interference in the retruded path should be removed

without changing the original intercuspal rela- tionship. These ideas are often confusing to the clinician because it is difficult, if not impossible, to document

on a statistical basis that one position is better than another. What appears to be of singular importance is that

there should be a position where the teeth intercuspate. In the naturally occurring healthy occlusion, postural position, occlusal vertical dimension, postural vertical

dimension, and free-way space are of academic interest only. If the occlusion is healthy and all its parts are

functioning to maintain it, then there is no need to alter the occlusal vertical dimension. However, in

situations where, through loss, migration, or wear of teeth, the occlusal vertical dimension is less than would

be found normally, change in this dimension may be necessary. It is here that occlusal vertical dimension and

free-way space become significant to the clinician. Free-way space measured in the premolar area is generally found to be in the range of 3 to 5 mm. However,

any projected change in this dimension—either increase or decrease— should be approached with extreme

caution, and a reasonable trial period should be instituted prior to the insertion of the completed prosthesis. In developing a therapeutically established intercuspal relationship, the concept of centric relation is

important. Although this term is relatively easy to define (it has at least 20 different definitions), it appears

that centric relation is most difficult to find, at least from the standpoint that so many groups disagree on

where it should be. Amsterdam (1974) has defined it as "the most favorable max-illo-mandibular relation at

which position we would like to establish the maximum intercuspation of the teeth — whether by using full

dentures, or occlusal adjustment of the natural dentition by selective grinding, orthodontics, restorative

dentistry—including fixed and removable prosthesis, as well as periodontal prosthesis." The essential in-

gredients of centric relation are terminal condyle positioning, bilateral simultaneous neuromuscular activity,

and maximum intercuspal relationship occurring at an occlusal vertical dimension that will allow for an

adequate free-way space. In altering the existing occlusion, at least two major objectives should be achieved: first, the new relationship

must be physiologically acceptable to the patient, and second, it should be reproducible. Patient acceptability

should include adequate mastication, phonation, and esthetics and can often be evaluated in a provisional

prosthesis. Reproducibility of the new occlusion has two components: first, it should be reproducible for us to

solve our transfer and adjustment techniques, and second and more important, it should be reproducible for

the patient in that the mandible should be able to assume this position without any patient awareness of a

change in position. It has been observed clinically that if the posterior teeth are made to intercuspate

simultaneously aT an occlusal vertical dimension that does not infringe on interdental clearance (i.e., free-

way Chapter 42 Occlusal therapy 495 space), the patient is able to assume the position without an awareness of a change in the position. 2. Freedom of movement to and from the intercuspal position. The mandible must be able to move in all

directions out of the intercuspal position without impediment. If the mandible is restrained in these

movements, usually the teeth will either become mobile, wear excessively, or my ofascial pain dysfunction

will develop. A problem sometimes noted in extensive restorative dentistry is that the occlusal vertical is

increased too much. As a result, the anterior overjet is increased, thereby making the anterior in-cisal

guidance ineffectual. The mandible is then restrained from moving freely from the newly established

intercuspal relationship. 3. Development of an occlusion not noticeable to the patient. The healthy functioning masticatory system is

one in which the patient is totally unaware of the occlusion, being unaware of where the jaw is, of how the

teeth articulate, and of the vertical dimension. The newly established occlusion should meet the same criteria. 4. Maintenance of the newly established occlusal > scheme over a reasonable period of time. The

therapist must evaluate and decide whether the teeth will maintain the occlusal relationship or require some

adjunctive aid sikh as splinting. 5. Establishment of an occlusion with acceptable pho-nation, mastication, and esthetics. These are all

subjective judgments made by the patient. The dentist, of course, can influence the patient's judgment as to

the.adequacy of these items; however, eventually the patient must be satisfied. To review, then, the therapeutic occlusion is a man-made one. It should be based not on preconceived ideas,

but on our knowledge of the system as it functions in health and those factors that can affect it adversely. A

major decision of the therapist should be whether the occlusal problems can be solved or at least altered in the

original intercuspal position or must be changed to such a degree that another mandibular position should be

used. DIFFICULTIES IN OCCLUSAL THERAPY Most clinical concepts of occlusal therapy are applicable mainly to the Angle Class I, fairly intact dentition.

Unfortunately, many patients with periodontal disease and occlusal trauma have missing teeth and skeletal

and/or dental malocclusions. Provisions must be made for the occlusal management of these patients. Form and function of the masticatory system The forces on various groups of teeth differ. For example, only the posterior teeth and the mandibular anterior

teeth should have functional forces placed along their long axes. Forces on the maxillary anterior teeth are

directed primarily facially. Since teeth best withstand forces delivered along to their long axes (calling on the

greatest num ber of periodontal ligament fibers—the oblique group), it is reasonable to expeot that the posterior teeth as a

group function to support the occlusal vertical dimension. The anterior teeth as a group are not suited to

supporting the occlusal vertical dimension. Instead, they serve to disarticulate the posterior teeth during

excursive movements of the mandible. Thus it is not surprising that many patients with loss of posterior teeth have flared anterior teeth and a

decreased occlusal vertical dimension. The anterior teeth, called on to support the occlusal vertical dimension,

and which are actually in occlusal trauma, have responded by migrating to a new position. In many situations, the anterior teeth are not positioned to provide their function of disarticulating the

posterior teeth during mandibular excursions. A common clinical situation in which functional anterior

guidance is not present is the non-orthodontically corrected Angle Class II, division 1. These situations can be

treated by changing the, form of the anterior teeth so that they may better fulfill their role in disarticulating

the posterior teeth in excursive functions. Altered canine form (Fig. 42-1) • Altering the palatal form of the maxillary canine (or all of the maxillary anterior teeth, if necessary) by

providing a centric stop on an accentuated cingulum is indicated in the following situations: 1. Distal extension cases—allows the anterior teeth to function more like posterior teeth in supporting the

occlusal dimension 2. Non-orthodontically corrected Angle Class II, division 1—provides anterior guidance where the teeth are

not positioned to provide this function 3. Severe periodontal involvement of the posterior teeth — adds an additional vertical supporting stop A commonly held misconception is that one must change a canine into a premolar. If this in fact were done,

its lingual cusp would be a balancing interference. Our goal is to provide a platform on the palatal surface of

the canine. This occlusal surface of the platform should be perpendicular to the long axes of the mandibular

anterior teeth at the newly established occlusal vertical dimension. In Angle Class II, division 1 malocclusions, placing the platform on the anterior teeth will allow the maxillary

and mandibular teeth to contact. This will provide for immediate disarticulation of the posterior teeth when

the mandible moves in excursions. OCCLUSAL APPLIANCES Occlusal appliances are used in dentistry in the diagnosis and treatment of a variety of dental disorders. Tooth

hypermobility, myofascial pain dysfunction syndrome (MPDS), and disorders of the condyle-disk assembly

are just a few situations where appliances are often quite 496 ANTIINFECTIVE AND ADJUNCTIVE MANAGEMENT OF PERIODONTAL DISEASES

Fig. 42-1. A, Left, Normal anterior relationship. Note anterior direction of force on maxillary canine. Center,

Restoring lost verticaj dimension and using centric relation as preferred jaw position opens some interarch

space. Right, Canine restored with altered canine form. Note redirection of force on maxillary canine. B,

Lingual form of all anterior teeth has been modified in treatment of nonorthodontically corrected Angle Class

II, division 1. Anterior guidance has been established. C, Various restorative materials may be used to alter

lingual form of anterior teeth. Depicted is an etched cast metal retainer, bonded to a maxillary canine. Rest

preparations have been placed to accept a removable partial denture. (A courtesy Dr. M. Amsterdam,

Philadelphia.)

Fig. 42-2. A, Modified Hawley bite plane. Component parts include anterior bite plane, labial bow, and "C

clasps on most posterior abutment teeth. B, Properly adjusted modified Hawley bite plane—"Gothic arch"

tracings from excursive contacts of each opposing tooth. Chapter 42 Occlusal therapy 497 useful. When they are properly used, great benefit can be realized. Classification 1. Sectorial appliances. These appliances contact a sector or group of teeth as opposed to all of the teeth. An

example of this type of appliance is the modified Hawley bite plane (Fig. 42-2). 2. Full-coverage appliances. These appliances contact all of the teeth. An example of this type of appliance

is the maxillary full-occlusal splint (night guard) (Fig. 42-3). Use of sectorial appliances Since sectorial appliances do not touch all of the teeth, these devices provide less control of the occlusal

changes that may occur. The modified Hawley anterior bite plane, for example, disarticulates the posterior

teeth. As a result. the posterior teeth are free to erupt. This can be beneficial if desired. However, eruption of

the posterior teeth in an anterior open-bite case will make matters worse. Other sectorial appliances include the Sved appliance, the mandibular orthopedic repositioning appliance

(MORA), the pivot, and flexible athletic mouthguards.

Fig. 42-3. A, Maxillary full occlusal splint. Occluding surface is flat, with as little guidance as can be

tolerated. B, Each opposing tooth touches occluding surface of night guard with at least one contacting point.

Use of full-coverage appliances Full-coverage appliances are used very often in clinical practice. They provide a tremendous amount of

control, in the sense that, assuming they fit well and are properly adjusted, very few untoward effects should

be anticipated. Full-coverage appliances in general, the night guard in particular, are most commonly used for

long-term nocturnal habit-control therapy and long-term mandibular repositioning. Guidelines in the use of occlusal appliances 1. An assessment must be made of the patient's skeletal dental-muscular relationship. The muscular pattern

may be either strong, weak, or average. The skeletal pattsrn may be classified as either dolichocephalic,

brachiocephalic, or normocephalic. This can be determined by examining the patient in profile. If the

mandibular plane is extended posteriorly and passes through the occiput, the patient is considered to be

dolichocephalic and have a skeletal open-bite pattern. These patients often have a short ramus, an obtuse

gonial angle, antegonial notching, and weak musculature. If the mandibular plane passes inferior to the oc-

ciput, the patient is brachiocephalic and displays a skeletal deep -bite tendency. These patients tend to have a

square acute gonial angle, short lower face, and strong musculature. A normocephalic or average skeletal

pattern is one in which the mandibular plane passes just below or crosses the base of the occiput. A sectorial appliance that disarticulates the posterior teeth should be used with the utmost caution in patients

with an anterior open-bite tendency. A sectorial appliance that disarticulates the anterior teeth should be used

cautiously in patients with a deep-bite tendency— dolichocephalic patients. There is a greater propensity for

these patients to intrude their posterior teeth, resulting in a posterior bite. In all cases the teeth-should occlude on smooth acrylic planes that allow freedom of movement into and out

of a maximum intercuspal position. Furthermore, the appliance should be thin enough so that the free-way

space is not interfered with. 2. Accuracy of fit of the appliance is as important as its design. The appliance should seat completely and be

stable. If the slightest instability is noted, the appliance should be relined or remade. Only after the

tooth/tissue fit is assured is the occlusion adjusted. 3. Occlusal appliances often enhance plaque and calculus development. Patients must be made aware of the

need to clean the appliance and the covered teeth. 4. Side effects such as dental pain and induced MPDS are possible with even the most benign of appliances.

It is the clinician's responsibility to carefully evaluate the patient at regular intervals (e.g., monthly) during the

entire time the appliance is worn. This includes the maintenance phase of therapy. Any adverse effects must

be noted and treated promptly. 498 ANTIINFECTIVE AND ADJUNCTIVE MANAGEMENT OF PERIODONTAL DISEASES OCCLUSAL ADJUSTMENT Retruded position Although the issue is controversial in its philosophy, we believe there are times when occlusal adjustment to

the retruded position warrants consideration. For an occlusion to mechanically free itself from the intercuspal

position, the anterior incisal guidance, posterior cusp height, and occlusal vertical dimension must be

coordinated. For example, if the anterior incisal guidance is too shallow relative to the posterior cusp height,

these cusps will probably clash in excursive movements of the mandible. Another example involves extruded

posterior teeth, which may result in an effective cusp height too steep for the anterior incisal guidance. A common example of the loss of harmony between anterior incisal guidance, posterior cusp height, and

occlusal vertical dimension occurs when some posterior teeth have been previously lost and the remaining

posterior teeth migrate, resulting in a decrease in the occlusal vertical dimension. Often this causes excessive

overloading of the maxillary anterior teeth with labial migration and diastema formation. Often in these

situations the remaining posterior teeth, especially the maxillary molars, have extruded, making their effective

posterior cusp height greater than originally. As a result of these complex adaptive movements, cusps

interfere in excursive movements. This results from the fact that their effective cusp heights are steeper and

that there is an increase in the effectiveness of the anterior incisal guidance associated with anterior flaring.

The problem, simply stated, is an anterior incisal guidance, posterior cusp height, and occlusal vertical di-

mension that are not in concert with each other. This is a situation wherein occlusal adjustment to the retruded

position may be effective. General considerations. When properly executed, occlusal adjustment procedures that establish a new

intercuspal relation in the retruded path of closure can be a sound and rational approach to occlusal

management of certain cases of occlusal trauma. Prior to instituting this therapy, it is important to determine

definitively whether the objectives of occlusal stability and freedom of mandibular movement can be obtained

in this new position. Certain severe malocclusions (such as the Class II, division I) often cannot be managed

solely by selective grinding and require orthodontic procedures; they may also require prosthetic placement of

the occlusal surfaces. Of major importance, but often overlooked, is the amount of tooth structure available for adjustment. The oc-

clusion with flat, worn cusps is generally not as amenable to selective grinding as that with steeper cusps.

Also, the type and degree of discrepancy between the retruded position and the intercuspal position must be

considered prior to therapy. For obvious mechanical reasons, the discrep ancy with a more vertical component

is usually easier to manage than the one with primarily a horizontal compo-

Fig. 42-4. A, "Normal" relationships of teeth in intercuspal position. Note anterior overbite and overjet,

mesiodistal landmarks of teeth, and buccolingual landmarks. B, "Usual" relationships of teeth when mandible

is in retruded contact position. Note decrease in anterior overbite and increase in overjet, mandibular

buccoclusal line lingual to maxillary central fossa line, and mandibular buccal cusp tips distal to opposing

marginal ridge areas. C, "Unusual" relationships of teeth when mandible is in retruded contact position. Note

increase in anterior overjet with little or no decrease in overbite, mandibular buccoclusal line in central fossa

line (not lingual to it), and mandibular buccal cusp tips distal to opposing marginal ridge areas. (From

Weisgold A and Rosenberg E: Occlusal therapy. In Goldman H et al, editors: Current therapy in dentistry, vol

6, St Louis, 1977, The CV Mosby Co.) nent (Fig. 42-4). Weinberg (1975) has investigated and compared the type and degree of discrepancy between

the retruded contact position and the intercuspal position. He noted: The amount of change in vertical dimension that accompanies the anterior slide will be inversely

proportioned to the expected degree of anterior condylar displacement. The more change in vertical

dimension that exists in proportion to the anterior slide, the less anterior condylar displacement we should

expect. When the change in vertical dimension is almost as great as the amount of anterior slide, then little

anterior condylar displacement should B

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Chapter 42 Occlusal therapy 499

be expected. When the change in vertical dimension approaches one third of the

anterior slide, then maximum anterior condylar displacement is produced with

normal TMJ function ... a deflective slide in centric relation to centric occlusion

does not necessarily mean anterior condylar displacement. Its diagnosis and

treatment depend on the correlation of three factors: the direction and magnitude

of the slide from centric relation to centric occlusion, the change in vertical

dimension of occlusion during the slide, and the position of the condyles in the

fossae when the teeth are in maximum occlusion (centric occlusion).

Generally, when the mandible is placed in the retruded path of closure, the

buccoclusal line angle of the mandibular posterior teeth relate lingually to (instead

of directly into) the maxillary central fossa line. This is because of the disparity in

size and shape of the mandible relative to the maxilla. Hence, when retruded, the

narrower anterior part of the mandible (and its teeth) relates lingually to a wider

part of the maxilla (and its teeth). When this occurs, the clinician is often able to

reshape the cusp tips and inclines to better relate the mandibular and maxillary

teeth. The advantage to this method is that cusp height can be decreased but the

vertical dimension of occlusion is not compromised, since the condyles are in a

more posterior and superior position. In fact, it is not uncommon to note an

increase in anterior overjet and decrease in overbite after performing this type of

adjustment, which has advantages.

There is a particular occlusal type that often is not treatable by selective grinding,

and the therapist must take extreme precautions not to upset the original

intercuspal relationship. Patients with this occlusal type often come for treatment

with a complaint that a dentist "just adjusted one tooth or cusp and ruined my

entire bite." Examination will frequently reveal a moderate overbite, greater than

normal overjet, relatively stable intercuspal position, moderate to flat posterior

cuspal form, worn mandibular incisal edges, 1 and at times posterior tooth contacts

in excursive movements. On further examination one notes a rather significant

discrepancy (greater than 4 mm) between the intercuspal position and retruded

contact position. This discrepancy is primarily horizontal in nature.

Temporomandibular radiography also shows a horizontal discrepancy between

these two positions, and the study casts reveal arches that are similar in size and

shape, as opposed to the commonly occurring situation of a disparity in size and

shape.

In this occlusal type, when the mandible is retruded, the mandibular buccoclusal

line angle does not relate lingually to the maxillary central fossa line, but in the

central fossa line. The mandibular teeth are merely more distal, but not lingual.

However, what has happened is that the cusp tips in a mesiodistal position are no

longer in opposing marginal ridge areas but now appose each other. The mandible

is now restrained from leaving the intercuspal position. Furthermore, since the

mandible is more distally placed, the anterior incisal guidance is not as effectual

as previ-

ously noted, and this further complicates mandibular glide patterns. Since the cusp

heights were minimal to begin with, it is difficult, if not impossible, to reduce

them. As stated, it is most wise to do little or no grinding whatsoever to avoid

changing the intercuspal relationship. Often all that the clinician can do for this

type of occlusal problem is to try to reassure the patient, use muscle relaxants

and/or exercises, and employ an occlusal appliance such as the full maxillary

night guard. The modified Hawley bite plane, on the other hand, must be used

with great care, for if the posterior teeth are left out of contact over a long period

of time, they may erupt to further complicate and aggravate the situation. If the

Hawley appliance is used, the posterior teeth should be kept in contact slight ly

and the anterior bite plane employed to provide for the loss of incisal guidance.

Use of selective grinding. Selective grinding is often indicated,when there is

evidence of trauma from occlusion or MPDS of known occlusal etiology, and/or

prior to restorative or prosthetic dentistry. A very common indication for this

therapeutic approach is in cases of primary occlusal traumatism. An approach to

selective grinding whereby the entire occlusal scheme is altered is discussed in the

following paragraphs. This technique should be employed only when the therapist

realizes that the occlusal disorder cannot be managed solely by adjusting the origi-

nal intercuspal relationship (i.e., when there are multiple nonworking

interferences, inadequate anterior overjet, trauma to the maxillary anterior teeth,

and/or an over-awareness of the occlusion).

The procedure is carried out in three steps.

Step 1. Correction of the landmark relationships of the teeth in the retruded

position of the mandible. The objectives of this step are to bring into simultaneous

contact the supporting inclines of the posterior teeth, to close the occlusal vertical

dimension sufficiently to provide for as effectual incisal guidance as possible, and

also to have the mandibular functional outer aspect areas positioned properly. An

additional advantage often will be gained because often the inclines that will have

to be adjusted are the same ones that interfere on the nonworking side. In other

words, completing this step properly will often eliminate some or all of the

nonworking interferences.

As mentioned previously, when the mandible is placed in the retruded path of

closure, the mandibular buccoclusal line angles will be lingual to the maxillary

central fossae. Similarly, the maxillary linguoclusal line angles will be buccal to

the mandibular central fossae. This will necessitate broadening the inner aspects

of the mandibular buccal cusps and maxillary lingual cusps to position the cusp

tips into their respective fossae.

Sometimes, however, the occlusal discrepancy is such that the mandibular

buccoclusal line angle is buccal to the maxillary central fossae. In this situation

narrowing of inclines would be indicated. 500 ANTIINFECTIVE AND ADJUNCTIVE MANAGEMENT OF PERIODONTAL DISEASES Step 2. Definition of the functional outer aspect (FOA) areas. The mandibular FOA may function to contact

the maxillary guiding cusps during glide movements of the mandible. Once step 1 is essentially completed, a

marking medium (e.g., articulating paper) is placed between the teeth and the patient is instructed to move the

mandible from side to side (in effect creating horizontal glide movements). Grinding is now done by

removing all markings on the outer aspects of the 1 mm band of FOA. Optimally, once completed, the dentist

should be able to see a 1 mm ribbon on the outer aspects of all the teeth; this is the "functional outer aspect."

Often, however, because of tooth position and limitations of grinding, this will not be a perfect 1 mm line. As a general rule, once the FOA is established, it usually will riot be altered. Step 3. Adjustment of the guiding inclines. The guiding cusps are those that have the potential for contact only

in glide movements. Step 3 is generally accomplished by having the patient move the mandible forward and

also to the side. An impediment to mandibular movement should be managed by adjusting the guiding

inclines of the maxillary teeth (i.e., inner aspects of buccal cusps and lingual of anterior teeth). If major

adjustments must be made on the maxillary anterior teeth, the patient should be notified of this and his

permission granted before proceeding (Fig. 42-5).

Fig. 42-5. A, Maximum intercuspal position. Note edge-to-edge relationship of anterior teeth, steep posterior

cuspal form, and midline discrepancy. B, Right working movement. C, Left non-working movement. Note

nonworking interferences on molars and premolars. Arrow indicates nonworking interference occurring

between | 7 and p7~. D, Retruded contact position. Note anterior "open bite" and landmark relationships of

posterior teeth on right and left sides. (From Weisgold A and Laudenbach K..: Alpha Omegan 69:60, Dec

1976.) Chapter 42 Occlusal therapy 501 An effort should be made at this time to eliminate all at the completion of this phase of adjustment and

remove cross-tooth interferences. Cross-tooth interferences are working and nonworking interferences that

were newly those that occur in a working movement and will be lo- created. cated on the inner aspects of the mandibular lingual cusps Finally, polishing all tooth surfaces is

extremely impor-

and outer aspects of maxillary lingual cusps. Since the ad- tant at the completion of selective grinding.

If inclines are justment during step 3 will be made on the guiding in- left rough, the patient will often concentrate on

this area or clines of the maxillary teeth, there is always the possibility find the sound disturbing. of inadvertently decreasing the working side rise. In ef- At the completion of therapy using the

above approach, feet, this can result in the generation of working and non- no discrepancy should be discernible between

the retruded working interferences. The same problem can develop if position and the intercuspal position. In other

words, the grinding of the maxillary anterior teeth is overzealous. The teeth will have been reshaped to articulate in

the retruded clinician must check all excursive movements thoroughly path of closure. There should be no "centric

slip." How-

Fig. 42-5, cont'd, E, Occlusal view of maxillary right side. Markings were made in mandible's retruded path

of closure. Note intitial interference (largest marking) occurring on mesiolingual cusp of maxillary second

moiar (arrow). F, Occlusal view of maxillary right side. These markings were made as a result of mandible

moving to opposite (i.e., left) side. This is a right-sided non-working interference that is occurring on

mesiolingual cusp of maxillary second molar. Direction of nonworking interference is oblique and runs in a

mesiolingual to distobuccal path (arrow). Note also that in this particular patient, same cusps that interfered

in retruded path also interfered on nonworking side. G, Mirror view of mandibular right side. Note markings

on second molar. Because this tooth is extruded beyond occlusal plane, it interferes both in retruded position

and on nonworking side. Arrow indicates nonworking interferences on buccal cusps of ~l\ . H, Maxillary

Hawley bite plane inserted. Continued. 502 ANTIINFECTIVE AND ADJUNCTIVE MANAGEMENT OF PERIODONTAL DISEASES

Fig. 42-5, cont'd. I. Appearance of patient after wearing appliance for 4 weeks while sleeping. Note anterior

tooth relationship In retruded path of closure, buccolingual relationships of posterior teeth, and midline.

Patient has been comfortable during this period of time. J, Appearance after selective grinding. Note midline

and degree of anterior overbite and overjet (compare with A). K, Appearance after selective grinding—right

working movement (compare with B). L, Appearance after selective grinding—left nonworking movement

(compare with C). ever, our observations have shown that in time a discrepancy generally appears and usually measures approxi-

mately 1 mm. Why has this occurred? Explanations that have been offered to the profession are that the

mandible is seeking to return to its original position or some form of condylar remodeling has occuired.

These are plausible explanations, but another possibility is that a tooth (or possibly a pair of teeth) has moved

slightly. Now when the mandible is placed in the retruded position, the teeth that interfere are those that have

moved; then the mandible slides forward into the intercuspal position—not the one that the patient originally

had, but the one that, was therapeutically developed by the dentist. Further investigations will hopefully give

us a better insight into this perplexing problem. Management of the nonworking interference. This interference is probably the most destructive: once it is

operational, the teeth strike each other off their axes, generating lateral forces destructive to the periodontium.

Because of its importance, various techniques are mentioned as follows: 1. Elimination of interference during adjustment of step I. This is discussed earlier in the chapter. 2. Channeling or ''trolley-tracking." The nonworking interference is marked on the mandibular tooth, and a

groove is created on the inner aspect of the tooth so that the maxillary lingual cusp can move through it

without interference. 3. Shallowing the opposing fossa. A restoration is placed in an opposing central fossa area, thereby making it more shallow. In maximum intercuspation the opposing cusp tip may now be in premature contact.

If so, the opposing cusp tip is shortened to obtain correct contact. In doing so, the nonworking interference is

eliminated while tooth contact is retained during intercuspation. 4. Increasing the opposite side working guidance. This increase is usually accomplished by restorative den-

tistry.

5. Extraction. Often an unopposed mandibular third molar will erupt in such a direction that it will interfere

on the nonworking side. Extraction of the third molar is often the best treatment. Use of selective grinding and restorative or prosthetic dentistry. The objectives and technique for this form of

adjustment are the same as those for selective grinding alone, differing only in the extent of therapy. Re-

storative or prosthetic dentistry is warranted when the therapist has decided that the objectives cannot be

achieved and maintained solely by selective grinding. Generally, the occlusion is adjusted to remove

interferences in the retrudcd path of closure, and the quadrants opposing the edentulous spaces are reshaped

to create a functional occlusal environment. It is extremely important that the remaining natural teeth support

the vertical dimension when a removable prosthesis is being used. Otherwise, the removable prosthesis will

settle and the natural teeth will in fact support centric occlusion. Adjusting the existing occlusion Adjusting the existing occlusion is a very common way of treating occlusal problems; however, correction of

the existing intercuspal position should be undertaken only after careful evaluation of the occlusion. Selection

of the intercuspal position as the jaw position of choice limits the therapist, since all the factors of occlusion

should now be considered fixed. In other words, cusp height, incisal guidance, and occlusal vertical

dimension cannot be altered, which makes this form of adjustment difficult. Also, if occlusal grinding is to be

extensive and is done in this position, there is a good possibility that either the occlusal vertical dimension

will be closed or the cusps that originally supported this position will be altered, causing a change in jaw

relationships. If in spite of the limitations, the clinician can predict achievement of the objectives by correcting the

occlusion in the intercuspal position, there is little reason not to use it. Splinting. Aside from being a means of replacing missing teeth, splinting is an indicated mode of therapy

when the alveolar bone height is so compromised that tooth mobility is increasing, mastication is difficult,

and the patient is unable to use the dentition in a comfortable manner: Chapter 42 Occlusal therapy 503 I. Temporary splints A. Extracoronal type 1. Wire ligation 2. Orthodontic bands 3. Removable acrylic appliances 4. Removable cast appliances 5. Bonded metal mesh 6. Light-cured composite 7. Combinations of the above B. Intracoronal type 1. Wire and acrylic 2. Wire and amalgam 3. Wire and light-cured composite 4. Wire, amalgam, and acrylic 5. Cast chrome cobalt bars with amalgam, acrylic, or both i 6. Combinations of the above II. Provisional splints A. All acrylic B. Adapted metal band and acrylic III. Permanent splints A. Etched bonded metal retainer B. Partial-coverage fixed prosthodontics C. Full-coverage fixed prosthodontics Temporary splints are usually placed during active periodontal

therapy. They are not as durable as permanent splints and often must be repaired periodically. Provisional splints are splints that are fabricated as part of a

restorative dentistry program, such as full-coverage provisional splints. They are used to evaluate a new

occlusal scheme, as well as to provide temporary coverage prior to insertion of the final prosthesis. The

permanent splint is the final prosthesis; however, the term permanent splint is a misnomer. Almost nothing is

permanent in dentistry or in any other discipline. Unfortunately, the term seems to be with us to stay. DISEASES RELATED TO PATHOLOGIC OCCLUSION Tooth hypermobility and retrograde wear arc two of me major symptoms of pathologic occlusion. In many in-

stances a pathologic occlusion may manifest itself with the appearance of extraoral symptoms. These

extraoral diseases have traditionally beer, placed in the catchall category of temporomandibular joint

syndrome. Recent advances in diagnosis and treatment have resulted in their being renamed to more

accurately describe their cause. Myofascial pain dysfunction syndrome In MPDS, pain is caused by spasm of the muscles of mastication and/or the cervical musculature. The causes

of the muscle spasm can be varied, and there is often a strong psychologic component. Before we modify the

patient's occlusion in the treatment of MPDS, we must be able to

*

504 ANTIINFECTIVE AND ADJUNCTIVE MANAGEMENT OF

PERIODONTAL DISEASES

unequivocally indict the occlusion as a causative factor in the disease. As an aid,

occlusal appliances are often used to determine if the occlusion is a contributing

factor in the disease. Insertion of a well-fitting, noninterfering, full-coverage

maxillary night guard as an initial diagnostic/ therapeutic aid in patients with

MPDS is often successful in relieving symptoms. If this is the case, subsequent

adjustment of the occlusion may give long-lasting relief from MPDS.

Disorders of the condyle-disk assembly

In the normal temporomandibular joint, the meniscus is interposed between the

condyle and the articular eminence. Aberrations in the positions of these parts or

abnormalities of the individual parts (i.e., meniscus dislocations or perforations)

are termed disorders of the condyle-disk assembly. There is much disagreement as

to the cause of these problems. Many investigators believe that the occlusion is a

causative factor. Others believe that muscular or local intracapsular factors are the

cause. Treatment of these disorders often involves the use of occlusal appliances.

They function to relax the muscles of mastication, ' to unload the

temporomandibular joint, and very often to reposition the mandible in order to

recapture a dislocated meniscus.

CONCLUSIONS

The research data as to the efficacy of occlusal adjustment are sparse as of this

time. Clinical observations over long periods of time give us the strong

impression that minimizing forces on the teeth is beneficial to the periodontium,

especially if it is compromised as a result of infectious periodontitis and occlusal

traumatic lesions combined.

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SUGGESTED READINGS Anderson D: Measurement of stress in mastication. II. J Dent Res 35:671, 1956. Apes T and Mcllwain JE Jr: The multiple uses of acid etch techniques, Dent Surv sm^ ;QT.;. Baumgarten HS and Garber D: The use and abuses of occlusal appliances, Alpha Omegan 78:57, 1985. Ericsson I and Lindhe J: Lack of effect of trauma from occlusion on the recurrence of experimental periodontitis, J Clin

Periodontal 4:115 1977. Ericsson I and Lindhe J: The effect of long standing jiggling on experimental marginal periodontitis in the beagle dog, J

Clin Periodontal 9:497, 1982. Ericsson I and Lindhe J: Lack of significance of increased tooth mobility in experimental periodontitis, J Periodontol

55:447, 1984.

Farrar WB and McCarty WL: A clinical outline of temporomandibular joint diagnosis and treatment, ed 7, Montgomery,

Ala, 1983, Nor-mandie Study Group for TMJ Dysfunction. Goodman P, Greene C, and Laskin D: Response of patients with myofascial pain-dysfunction syndrome to mock

equilibration. J Am Dent Assoc 92:755, 1976. Kayne B: Criteria for occlusal alteration in the management of cranio-mandibular dysfunction, Alpha Omegan 78:47, 1985. Kegel W, Selipsky H, and Phillips C: The effect of splinting oh tooth mobility. I. During initial therapy, J Clin Periodontol

6:45, 1979. Lindhe J and Nyman S: Occlusal therapy. In Lindhe J. editor: Textbook of clinical periodontology, Copenhagen, 1984,

Munksgaard. Lindhe J, Nyman S, and Ericsson 1: Trauma from occlusion. Iti Lindhe J, editor: Textbook of periodontology, Copenhagen,

1984, Munksgaard. Miller GM and Kreuzer DW: The modified Hawley appliance, HI, Int J Periodontics Restorative Dent 2:55, 1982. Mohl NP et al: Textbook of occlusion, Chicago, 1988, Quintessence Publishing Co, Inc. Nyman S et al: The significance of alveolar bone in periodontal disease, J Periodortt'Res 19:520, 1984. Pihlstrtim B et al: Association between signs of trauma from occlusion and periodontitis, J Periodontol 57:1, 1986. Poison AM, Meitner SW, and Zander HA: Trauma and progression of marginal periodontitis in squirrel monkeys. IV.

Reversibility of bone loss due to trauma alone and trauma superimposed upon periodontitis, J Periodont Res 11:290, 1976. Potashnick S and Abrams L: The significance of occlusal adjustment in peridontal therapy, Alpha Omegan 78:25, 1985. Rosling B, Nyman S, and Lindhe J: The effect of systemic plaque control on bone regeneration in infrabony pockets. J Clin

Periodontol 3:38. 1976. Sved A: Changing the occlusal level and a new method of retention, Am J Orthod 30:527, 1944. Weisgold A: A review of the various concepts of occlusion: a historical perspective, Alpha Oinegan 66:9, Dec 1973. Wcisgold A and Laudenbach K: Occlusal etiology and management of disorders of the temporomandibular joint and

related structures. Alpha Omegan 69:60, Dec 1976. Weisgold A and Rosenberg E: Occlusal therapy. In Goldman H et al, editors: Current therapy in dentistry, vol 6. St Louis.

1977. The CV Mosby Co.