1. Is there pain or restriction on opening or closing of the mouth? Pain in the fully opened position (e.g., pain associated with opening to bite an apple, yawning) is probably caused by an extra-articular problem, whereas pain associated with biting firm objects (e.g., nuts, raw fruit and vegetables) is probably caused by an intra-articular problem.10 Limited opening may be due to the disc displaced anteriorly, inert tissue tightness, or muscle spasm. Restriction can lead to anxiety in patients because of its effect on everyday activities (e.g., eating, talking).³

2. Is there pain on eating? Does the patient chew on the right? Left? Both sides equally? Loss of molars or worn dentures can lead to loss of vertical dimension, which can make chewing painful. Vertical dimension is the distance between any two arbitrary points on the face, one of these points being above and the other below the mouth, usually in midline. Often, chewing on one side is the result of malocclusion.10

3. What movements of the jaw cause pain? Do the symptoms change over a 24-hour period? The examiner should watch the patient’s jaw movement while the patient is talking. A history of stiffness on waking with pain on function that disappears as the day goes on suggests osteoarthritis.11

4. Do any of these actions cause pain or discomfort: yawning, biting, chewing, swallowing, speaking, or shouting? If so, where? All of these actions cause movement, compression, and/or stretching of the soft tissues of the temporomandibular joints.

5. Does the patient breathe through the nose or the mouth? Normal breathing is through the nose with the lips closed and no “air gulping.” If the patient is a “mouth breather,” the tongue does not sit in the proper position against the palate. In the young, if the tongue does not push against the palate, developmental abnormalities may occur, because the tongue normally provides internal pressure to shape the mouth. The buccinator and orbicularis oris muscle complex provides external pressure to counterbalance the internal pressure of the tongue. Loss of normal neck balance often results in the individual’s becoming a mouth breather and an upper respiratory breather, making greater use of the accessory muscles of respiration. Conditions (such as, adenoids, tonsils, and upper respiratory tract infections) may cause the same problem.

6. Has the patient complained of any crepitus or clicking? Normally, the condyles of the temporomandibular joint slide out of the concavity and onto the rim of the disc. Clicking is the result of abnormal motion of the disc and mandible. Early clicking implies a developing dysfunction, whereas late clicking is more likely to mean a chronic problem. Clicking may occur when the condyle slides back off the rim into the center (Figure 4-7).¹² If the disc sticks or is bunched slightly, opening causes the condyle to move abruptly over the disc and into its normal position, resulting in a single click (see Figure 4-7).¹³ There may be a partial anterior displacement (subluxation) or dislocation of the disc, which the condyle must override to reach its normal position when the mouth is fully open (Figure 4-8). This override may also cause a click. Similarly, a click may occur if the disc is displaced anteriorly and/or medially, causing the condyle to override the posterior rim of the disc later than normal during mouth opening. This is referred to as disc displacement with reduction. If clicking occurs in both directions, it is called reciprocal clicking (Figure 4-9). The opening click occurs somewhere during the opening or protrusive path, and the click indicates the condyle is slipping over the thicker posterior border of the disc to its position in the thinner middle or intermediate zone. The closing (reciprocal) click occurs near the end of the closing or retrusive path as the pull of the superior lateral pterygoid muscle causes the disc to slip more anteriorly and the condyle to move over its posterior border.
Clicks may also be caused by adhesions (Figure 4-10), especially in people who clench their teeth (bruxism). These “adhesive” clicks occur in isolation, after the period of clenching.¹⁴ If adhesions occur in the superior or inferior joint space, translation or rotation will be limited. This presents as a temporary closed lock, which then opens with a click.
If the articular eminence is abnormally developed (i.e., short, steep posterior slope or long, flat anterior slope), the maximum anterior movement of the disc may be reached before maximum translation of the condyle has occurred. As the condyle overrides the disc, a loud crack is heard, and the condyle-disc leaps or jogs (subluxes) forward.14
“Soft” or “popping” clicks that are sometimes heard in normal joints are caused by ligament movement, articular surface separation, or sucking of loose tissue behind the condyle as it moves forward. These clicks usually result from muscle incoordination. “Hard” or “cracking” clicks are more likely to indicate joint pathology or joint surface defects. Soft crepitus (like rubbing knuckles together) is a sound that sometimes occurs in symptomless joints and is not necessarily an indication of pathology.15 Hard crepitus (like a footstep on gravel) is indicative of arthritic changes in the joints. The clicking may be caused by uncoordinated muscle action of the lateral pterygoid muscles, a tear or perforation in the disc, osteoarthrosis, or occlusal imbalance. Normally, the upper head of the lateral pterygoid muscle pulls the disc forward. If the disc does not move first, the condyle clicks over the disc as it is pulled forward by the lower head of the lateral pterygoid muscle. Iglarsh and Snyder-Mackler⁷ have divided disc displacement into four stages (Table 4-1).

7. Has the mouth or jaw ever locked? Locking may imply that the mouth does not fully open or it does not fully close and is often related to problems of the disc or joint degeneration. Locking is usually preceded by reciprocal clicking. If the jaw has locked in the closed position, the locking is probably caused by a disc with the condyle being posterior or anteromedial to the disc. Even if translation is blocked (e.g., “locked” disc), the mandible can still open 30 mm by rotation. If there is functional dislocation of the disc with reduction (see Figure 4-8), the disc is usually positioned anteromedially, and opening is limited. The patient complains that the jaw “catches” sometimes, so the locking occurs only occasionally and, at those times, opening is limited. If there is functional anterior dislocation of the disc without reduction, a closed lock occurs. Closed lock implies there has been anterior and/or medial displacement of the disc so that the disc does not return to its normal position during the entire movement of the condyle. In this case, opening is limited to about 25 mm, the mandible deviates to the affected side (Figure 4-11), and lateral movement to the uninvolved side is reduced.¹⁴ If locking occurs in the open position, it is probably caused by subluxation of the joint or possibly by posterior disc displacement (see Figure 4-11). With an open lock, there are two clicks on opening, when the condyle moves over the posterior rim of the disc and then when it moves over the anterior rim of the disc, and two clicks on closing. If, after the second click occurs on opening, the disc lies posterior to the condyle, it may not allow the condyle to slide back (Figure 4-12).¹⁶ If the condyle dislocates outside the fossa, it is a true dislocation with open lock; the patient cannot close the mouth, and the dislocation must be reduced.¹⁶

8. Does the patient have any habits, such as smoking pipes, using a cigarette holder, leaning on the chin, chewing gum, biting the nails, chewing hair, pursing and chewing lips, continually moving the mouth, or any other nervous habits? All these activities place additional stress on the temporomandibular joints.

9. Does the patient grind the teeth or hold them tightly? Bruxism is the forced clenching and grinding of the teeth, especially during sleep. This may lead to facial, jaw, or tooth pain, or headaches in the morning along with muscle hypertrophy. If the front teeth are in contact and the back ones are not, facial and temporomandibular pain may develop as a result of malocclusion. Normally, the upper teeth cover the upper one third of the bottom teeth (Figure 4-13).

10. Does there appear to be any related psychosocial problems? Temporomandibular dysfunction is often accompanied by related psychosocial issues.1,17 Table 4-2 outlines psychosocial factors that may affect the temporomandibular joint.

11. Are any teeth missing? If so, which ones, and how many? The presence or absence of teeth and their relation to one another must be noted on a table similar to the one shown in Figure 4-6. Their presence or absence can have an effect on the temporomandibular joints and their muscles. If some teeth are missing, others may deviate to fill in the space, altering the occlusion.

12. Are any teeth painful or sensitive? This finding may be indicative of dental caries or abscess. Tooth pain may lead to incorrect biting when chewing, which puts abnormal stresses on the temporomandibular joints.

13. Does the patient have any difficulty swallowing? Does the patient swallow normally or gulp? What happens to the tongue when the patient swallows? Does it move normally, anteriorly, or laterally? Is there any evidence of tongue thrust or thumb sucking? For example, the facial nerve (cranial nerve VII) and the trigeminal nerve (cranial nerve V), which control facial expression and mastication and contribute to speech, also control anterior lip seal. If lip seal is weakened, the teeth may move anteriorly, an action that would be accentuated in “tongue thrusters.” The normal resting position of the tongue is against the anterior palate (Figure 4-14). It is the position in which one would place the tongue to make a “clicking” sound.

14. Are there any ear problems such as hearing loss, ringing in the ears, blocking of the ears, earache, or dizziness? Symptoms such as these may be caused by inner ear, cervical spine, or temporomandibular joint problems.

15. Does the patient have any habitual head postures? For example, holding the telephone between the ear and the shoulder compacts the temporomandibular joint on that side. Reading or listening to someone while leaning one hand against the jaw has the same effect.

16. Has the patient noticed any voice changes? Changes may be caused by muscle spasm.

17. Does the patient have headaches? If so, where? Temporomandibular joint problems can refer pain to the head. Is there any history of infection or swollen glands?

18. Does the patient ever feel dizzy or faint?

19. Has the patient ever worn a dental splint? If so, when? For how long?

20. Has the patient ever been seen by a dentist, such as a periodontist (a dentist who specializes in the study of tissues around the teeth and diseases of these tissues), an orthodontist (a dentist who specializes in correction and prevention of irregularities of the teeth), or an endodontist (a dentist who specializes in the treatment of diseases of the tooth pulp, root canal, and periapical areas)? If so, why did the patient see the specialist, and what was done?

1. Is the face symmetrical horizontally and vertically, and are facial proportions normal (Figure 4-15)? The examiner should check the eyebrows, eyes, nose, ears, and corners of the mouth for symmetry on both horizontal and vertical planes. Horizontally, the face of an adult is divided into thirds (Figure 4-16); this demonstrates normal vertical dimension. Usually the upper and lower teeth are used to measure vertical dimension. The horizontal bipupital, otic, and occlusive lines should be parallel to each other (Figure 4-17). Loss of teeth on one side can lead to convergence in which at least two of the lines may converge because the jaw line is short on one side relative to the other. A quick way to measure the vertical dimension is to measure from the lateral edge of the eye to the corner of the mouth and from the nose to the chin (Figure 4-18). Normally, the two measurements are equal. If the second measurement is smaller than the first by 1 mm or more, there has been a loss of vertical dimension, which may have resulted from loss of teeth, overbite, or temporomandibular joint dysfunction. In children, elderly persons, and those with massive tooth loss, the lower third of the face is not well developed (lack of teeth) or has recessed (Figure 4-19). As the teeth grow, the lower third develops into its normal proportion. The examiner should notice whether there is any paralysis, which could be indicated by ptosis (drooping of an eyelid) or by drooping of the mouth on one side (Bell palsy).

2. The examiner should note whether the teeth are normally aligned or there is any crossbite, underbite, or overbite (Figure 4-20). With crossbite, the teeth of the mandible are lateral to the upper (maxillary) teeth on one side and medial on the opposite side. There is abnormal interdigitation of the teeth. With anterior crossbite, the lower incisors are ahead of the upper incisors. With posterior crossbite, there is a transverse abnormal relation of the teeth. In underbite, the mandibular teeth are unilaterally, bilaterally, or in pairs in buccoversion (i.e., they lie anterior to the maxillary teeth). In overbite, the anterior maxillary incisors extend below the anterior mandibular incisors when the jaw is in centric occlusion. A small amount of overbite (2 to 3 mm) anteriorly is the most common position of the teeth. This is because the maxillary arch is slightly longer than the mandibular arch. Overjet (Figure 4-21) is the distance that the maxillary incisors close over the mandibular incisors when the mouth is closed. This distance is normally 2 to 3 mm. Occlusal interference refers to premature teeth contact, which tends to deflect the jaw laterally and/or anteriorly.¹⁸ Any orthodontic appliances or false teeth present should also be evaluated for fit and possible sore spots.

3. The examiner should note whether there is any malocclusion that may result in a faulty bite. Malocclusion may be a major factor in the development of disc problems of the temporomandibular joints. Occlusion occurs when the teeth are in contact and the mouth is closed. Malocclusion is defined as any deviation from normal occlusion. Class I occlusion refers to the normal anteroposterior relation of the maxillary teeth to mandibular teeth. A slight modification with only the incisors affected and overjet slightly larger is sometimes classified as a Class I malocclusion. Class II malocclusion (overbite) occurs when the mandibular teeth are positioned posterior to their normal position relative to the maxillary teeth. This malocclusion deformity involves all the teeth, including the molars. The designation Class II Division 1 malocclusion (also called large overjet or horizontal overlap) indicates that the maxillary incisors demonstrate significant overjet. Class II Division 2 malocclusion (also called deep overbite or vertical overlap) implies that overjet is not significant but that there is overbite and lateral flaring of the lateral maxillary incisors.19 Class III malocclusion (i.e., underbite) occurs when the mandibular teeth are positioned anterior to their normal position relative to the maxillary teeth. If maxillary and mandibular teeth are on the same vertical plane, a Class III malocclusion would be present.

4. What is the facial profile? The orthognathic profile is the normal, “straight-jawed” form. With this facial profile, a vertical line dropped perpendicular to the bipupital line would touch the upper and lower lips and the tip of the chin. In a person with a retrognathic profile, the chin would lie behind the vertical line and the person would be said to have a “receding chin.” With the prognathic profile, the chin would be in front of the vertical line and the person would have a protruded or “strong” chin (Figure 4-22).¹⁹

5. The examiner should note whether the patient demonstrates normal bony and soft-tissue contours. When the patient bites down, do the masseter muscles bulge as they normally should? Hypertrophy caused by overuse may lead to abnormal wear of the teeth. When looking at the soft tissues, it is important to note symmetry. The upper lip should normally cover two thirds of the maxillary teeth at rest. If it does not, the lip is said to be short.7 If the lip can be drawn over the upper teeth, however, the upper lip is said to be functional, and no treatment is necessary. The lower lip normally covers the mandibular teeth and, when the mouth is closed, part of the maxillary teeth.

6. Is the patient able to move the tongue properly? Can the patient move the tongue up to and against the palate? Can the tongue be protruded or rolled? Is the patient able to “click” the tongue? Tongue thrusting refers to forward movement of the tongue, usually to push against the lower teeth; it also occurs when the tongue is pushed against the upper teeth and the lower teeth are closed firmly against it, creating an oral seal.20 Tongue thrusters find it easier to thrust the tongue if the head is protruded. Therefore, to test for tongue thrusting, the patient’s head posture is corrected and the patient is asked to swallow. In the tongue thruster, swallowing causes the tongue to move forward resulting in protrusion of the head. Tongue thrusting may be due to hyperactivity of the masticatory muscles. When one swallows, the hyoid bone should move up and down quickly. If it moves only upward and slowly, and the suboccipital muscles posteriorly contract, it is suggestive of a tongue thrust.²¹

7. Where does the tongue rest? Is the tongue bitten frequently? Does the tongue have any scalloping or ridges? Does the patient swallow normally? Do the lips part when swallowing? What is the tongue position when swallowing? Do the facial muscles tighten on swallowing? All of these factors give the examiner some idea of the mobility of the structures of the mouth and jaw and their neurological mechanisms.