Clinical and Instrumental Functional Analysis for Diagnosis and Treatment Planning, Part 3: Clinical Functional Analysis

Diagnosis and treatment planning for orthodontic patients have been based, for the most part, on static materials--dental casts, which are either hand-held or mounted in a nonadjustable articulator, and lateral cephalometric x-rays. In this series, I am proposing a dynamic, functional analysis in two parts--a clinical functional analysis and an instrumental functional analysis.

Patient Interview

The first step in a clinical functional analysis is an interview in which prospective patients are asked a series of questions to assess their past medical and dental experience and their current health status. History-taking in which the patient or parent is asked to check off pertinent conditions is not satisfactory for a complete and accurate assessment. Much more and better information is gotten from a personal interview. I like to conduct this interview myself, because this contact is also important in establishing a doctor-patient relationship, in probing deeper into the patient's medical and dental condition, and in motivating patient cooperation. This is especially important for child patients who are not accustomed to recognizing or discussing such matters, and who may be initially embarrassed or reticent to talk about them. The interview takes 20 minutes, and I consider it to be time well spent. Patients are asked a standard series of questions and affirmative answers are discussed and noted in detail.

Medical History

Have you ever had any problems related to:

1. Infections

2. Cardiovascular system

3. Respiratory system

4. Digestive system

5. Metabolism

6. Allergies

7. Urogenital system

8. Central nervous system

9. Psychiatric problems (any therapy?)

10. Rheumatic diseases

11. Hormonal system

12. Special medical problems (medication?)

Dental History

1. Do you have any problems when you chew?

2. Do you have any sensitive teeth?

3. Do any teeth bother you when you close, chew, or swallow?

4. Do you ever have pain when you open your mouth very wide or on a big bite or yawn?

5. Do your jaw joints make noises? If so, on which side?

6. Do you have any pain in front of, behind, or in your ears?

7. Do you suffer from headaches? Morning, noon, or evening?

8. Do you ever have cramps or spasms in head, neck, or throat?

9. Do you ever have a feeling your mouth is dry, hot, or burning?

10. Do you ever have to look for space or place to close?

Positive responses are graded: light = 1, medium = 2, severe = 3. The sum of the graded answers constitutes an occlusal index that I use as a guide to the severity of dysfunction in the stomatognathic system. If the occlusal index is less than 5, the problems are minimal. I only perform a clinical functional analysis and possibly a simple articulator mounting. From 7 to 10, I use a more detailed instrumental analysis. If the number is significant (around 10 or more) I continue with questions:

11. Do you take drugs for the conditions described? What drugs?

12. Have you had problems in the head and neck area after an accident?

13. Did you have orthodontic treatment or equilibration in the past? How many years ago? How many equilibration sessions? What was the cause for the equilibration? Have you had periodontal problems? (This is an important group of questions because the patient may be dealing with some type of artificial occlusion.)

14. Do the problems you describe influence your general well-being?

15. When was the last time you had dental treatment? What was done?

16. What was your reason for coming to my office today?

17. Do you think there is a serious disorder or illness?

18. Do you think treatment is necessary?

19. Do you think we should discuss any related history?

20. Have you ever had a tendency to brux your teeth?

Now we are ready for the clinical functional analysis.

Muscle Examination

Muscles are palpated with the patient upright in a regular chair--not a dental chair--and with the operator facing the patient with weight evenly balanced on both feet and forearms parallel to the floor. We both have to be relaxed. The patient's head should be at the level of my elbow. I tell the patient, "I will apply uniform bilateral pressure. You tell me if it feels the same on both sides or different, and if it hurts." Meanwhile, I can feel if there is any tension in muscles. The findings are charted.

Shoulder and neck muscles are palpated first (Fig. 1). They control the anteroposterior and lateral position of the head. Head posture is correlated with many things, including eye dominance. If you are right-handed and have a dominant right eye you are always looking across your nose, and the more prominent your nose is, the more difficulty you have and the more you have to turn your head. Many dentists have neck problems that stem from being right-hand and right-eye dominant. This is also a reading problem, because one eye reads ahead of the other; and if you are left-handed and right-eyed it causes transposition problems in reading.

I incline the patient's head back to relax the posterior neck muscles (Fig. 2), palpate the shoulder and neck muscles, and move forward toward the atlanto-occipital connection (Fig. 3) to see if there is a difference between left and right, and if there is pain. I also palpate the posterior neck line with one finger (Fig. 4)

Next I evaluate the temporalis muscle, using a three-finger technique--the thumb is anterior just back of and above the eye, the second finger is on the middle belly, and the third finger is on the posterior belly (Fig. 5). The thumb and third finger are on the borders of the muscle. We ask the patient to close firmly. I palpate the posterior fibers, which are retrusive, and the superior and anterior fibers, which are the powerful closing muscles. I also palpate the temporalis intraorally where it inserts on the coronoid process. If the patient feels pain, it indicates a hyperactive temporalis. In 30% of the cases, the temporalis not only inserts on the coronoid process, but it also has some fibers going directly to the condyle; and these variations to the condyle may create TMJ problems.

The pterygoid muscles are highly involved in mandibular movement and in dysfunction. The medial and lateral pterygoid muscles are related to protrusion and closing action, and to unilateral rotational movement of the mandible. The superior head is a closing muscle correlated with the TMJ and the disc Its origin is high on the base of the skull with its fibers coming down and around the articular eminence to insert on the mandible with some fibers going directly to the disc (Fig. 6). Spasm of this muscle overloads the muscle fibers on the lateral pole of the joint. It is true that it is not possible to palpate the superior head of the lateral pterygoid directly, but I feel that palpation of the lateral poles gives me indirect information about it. Pain here indicates to me hyperactivity of the superior pterygoid, and may be an early symptom of a disc displacement. With equal pressure of the fingers on the lateral poles of the condyles as the patient opens and closes the mouth, I ask the patient if both sides feel the same, and if there is pain.

Behind the condyle and disc, there is a wide space of dense tissue called the retro-articular pillow that postures the condyle. This tissue cushions the condyle against a strong contraction of the temporalis muscle during mastication. I palpate this space with the patient's mouth open (Fig. 7). Pain may indicate a retrocapsulitis, or a traumatic problem in the posterior joint.

Next I palpate the inferior head of the lateral pterygoid. Using the small fingers, I slide back buccally and behind the tuberosity (Fig. 8). This muscle is involved in many dysfunction cases. I now palpate the medial pterygoid muscle (Fig. 9), sliding the index finger lingually and putting pressure on the insertion of this muscle above the corner of the mandible. There is often pain in the periosteum at this point.

On the mediotrusive side, the inferior head of the lateral pterygoid pulls the condyle forward and inward. Medial pterygoid action is cranial, medial, and anterior. Activity of these muscles rotates the mandible to the other side, causing Bennett movement. On the working side, the temporal muscle is active in closing. The superior head of the lateral pterygoid on this side causes intrusive motion of the condyle and disc. This important interaction between the inferior group on the mediotrusion side and the superior group on the working (laterotrusion) side is one of the most important actions of mandibular movement. There is always a correlation between balancing interferences and a highly sensitive spot at the insertion of the medial pterygoid.

Next is the masseter muscle, arising at the zygomatic ridge and proceeding inferiorly and posteriorly to insert at the lower portion of the ramus. Its activity closes the mandible and loads the joint cranially and anteriorly. The masseter has two bellies--superficial and deep (Fig. 10). I ask the patient for a power closure, and the superficial belly is clearly visible. I palpate its anterior and posterior borders with thumb and forefinger, asking the patient if it feels the same on both sides and if there is pain. I palpate the deep belly with one finger under the zygomatic arch in front of the ear (Fig. 11). The masseter muscle insertion varies. The more anterior the masseter insertion, the more horizontal the growth pattern will be; the more posterior the insertion, the more posterior rotating type of growth. Thus, the muscle pattern might have some implications for growth prediction.

Next is the suprahyoid muscle group, especially the digastric and mylohyoid muscles. They are active in positioning the hyoid bone (Fig. 12), in mouth opening and--especially the digastric--in mandibular retrusion, particularly if the mandible is open. The digastric is a link between superior and inferior hyoid muscles. It is highly involved in posture, swallowing, and speech problems.

The anterior belly of digastric is palpated in the floor of the mouth behind the symphysis (Fig. 13), and the mylohyoid muscle is palpated along the mylohyoid ridge (Fig. 14). There is often a difference between the right and left anterior bellies of digastric, and this indicates an asymmetry in function. The posterior belly of digastric is palpated outside the mouth on the neck just below the corner of the mandible (Fig. 15). With the patient's head tilted downward, the digastric is also palpated for sore spots along the inside border of the mandible.

I also look at the position of the hyoid bone (Fig. 16) and ask the patient to swallow as we watch the movement. I observe the patient's neck and the infrahyoid muscles as I ask the patient to breathe, speak, and swallow. I often find irregular contraction of these muscles in function, and they are often involved in head posture problems.

I palpate the infrahyoid group as I ask the patient to take a deep breath, to count from one to ten, and to swallow. I also palpate the attachment of the infrahyoid group (Fig. 17) and the sternohyoid muscles at the clavicle and sternum.

Next is the sternocleidomastoid muscle. I palpate its origin on the skull behind the ear and its insertion in the sternum and clavicle. I also palpate the belly with thumb and forefinger (Fig. 18). Sternocleidomastoid is involved in chewing and in posturing the head.

The tongue is an important and unique muscle. I have the patient stick the tongue out, and I observe the tooth impressions along the borders. I palpate the tongue bilaterally looking for asymmetries (Fig. 19). With the patient's head bent forward, I palpate under the mandible as the patient swallows, and I observe movement of the mandible on swallowing. The tongue is positioned against the lower front teeth during bruxism, and it pushes the mandible forward.

Mandibular Movement Analysis

Next in the clinical functional analysis is mandibular movement analysis. I have the patient open and close and move the jaw from left to right and forward. These movements are quantified by measurement with a ruler (Fig. 20) and examined qualitatively as well. Some patients with dysfunction open and close the jaw deviating from side to side. This indicates imbalance between the left and right opening and closing muscle groups. Often the patient deviates to one side on opening and closing. This may indicate spasm of the opening and closing muscles on the side to which the jaw deviates. Sometimes there is a straight opening for a distance and then a deviation to one side. This indicates limitation in the TMJ. The differential diagnosis among these movements is very important.

Next it is important to know the difference between joint-directed position of the mandible and position at maximum intercuspation. Gently guide the patient's jaw back to the physiologic border position (Fig. 21), to the point of first tooth contact in an unstrained posterior position, and have the patient hold this position. Observe the slide as the patient closes tight to a maximum intercuspation position.

Now we have to diagnose the joint condition. If the condyle is correctly seated, then you have a physiologic border position or reference position we refer to as RP. If the condyle is behind the disc, then you have an unphysiologic position we refer to as DRP or deranged reference position. I chart the slide from RP to maximum intercuspation.

Resiliency Test

Next is the clinical test of the joint resilience. Place one layer of mylar between the posterior teeth on one side and one layer of shimstock (.3mm) between the posterior teeth on the opposite side (Fig. 22). The patient should be able to close and hold the single layer of mylar between the teeth. If you add a layer of .3mm shimstock for a total of 0.6 mm, an adult with a healthy joint should still be able to hold the single layer of mylar between the teeth on the opposite side. In a child, you should be able to add another 0.3mm layer for 0.9mm altogether, and the occlusion should still hold the single layer of mylar on the other side (Fig. 23). Inability in this test may indicate some TMJ disorder.

Analysis of Occlusion

In functional analysis of the occlusion, the occlusion is divided into anterior, middle, and posterior segments. In closing the teeth tightly in occlusion, the strongest loading should be on the molars, with less loading on the bicuspids. The anteriors should be fairly unloaded but in close contact. In eccentric movement, I like to see contact on the laterotrusion side in the anterior region, and in some cases this guidance system extends through the bicuspid region. The molars should be disoccluded. I do an occlusogram in wax to see what kind of occlusion we have.

Warm the sheet of wax in your hands and place it on the teeth. Support the mandible and have the patient close in maximum intercuspation. Have the patient tap, tap, tap until you can hear the cusps hit. Remove the wax bite (Fig. 24), and hold it up to the light to see the occlusal contacts and the differences between left and right (Fig. 25). Chart the contacts. The front teeth should be unloaded.

Take a new sheet of wax, warm it, cover the teeth, support the mandible, and have the patient close in maximum intercuspation. In the closed position, ask the patient to pull the mandible back as far as possible and go forward. Then go back toward the left shoulder and back toward the right shoulder. Look to see where the perforations are--where the guidance systems are. They should be anterior to the molars and on the working side. This is a quick approach to charting and evaluating the occlusion. Functional and parafunctional interferences will be recorded.

Neurological Examination

The last sequence in the clinical functional analysis checks the neurological condition of the face. Start with the fifth cranial nerve (Fig. 26), palpating the supraorbital, infraorbital, and mentalis branches bilaterally with equal pressure (Fig. 27). Ask the patient if there is a difference between left and right and if there is pain. If there are symptoms, ask the patient to close the eyes and to differentiate between pressure on the skin of the face on each side with a dull and a sharp probe, and between warm and cold, to test the patient's perception and whether there is a difference between sides. Check eye motion by having the patient follow your finger up and down, left and right, and around and around.

Next check the seventh cranial nerve. Have the patient close the eyes, relax, raise the eyebrows, relax, blow out the cheeks, relax, raise the corners of the mouth (smile). I am very concerned about any discrepancy in the facial nerve function, because an asymmetry in left and right function is an important influence on the functional matrix.

In a few cases, I found that disturbances adding up to an occlusal index of around 11 points were not related to dysfunction, but to something going on in the neurological system. So if I find any evidence of pain or imbalance in our neurological examination, I immediately refer the patient for a neurological workup.

This completes the clinical functional analysis, and I am ready for the instrumental analysis.

ACKNOWLEDGMENT: Dr. Slavicek and JCO would like to thank William Missert, President of William Missert, Inc., a full-service commercial dental laboratory, and its subsidiary, Gamma Institute USA, for his invaluable assistance in the production of this series.