After a maximal movement of the mandible to the right, the distance from the upper midline to the lower mark is measured.
Right: Again, the specific entry is the jaw-opening value. The norm for men is 10.2 ± 2.3 mm and for women 10.3 ± 3.4 mm. The normal values given here for the two sides are taken from studies by Hesse (1996).
152 Active protrusive movement
To determine the extent of protrusion, the horizontal overlap ( over-jet”) is measured first and then added to the distance between the upper labial surface and the lower incisal edge after maximal protrusion. This can be done with either a simple ruler or with the back side of a commercial sliding caliper.
Right: Entry in the patient’s record is made in green or red. Normal values are 9.0 ± 2.8 mm for men and 9.1 ± 1.8 mm for women.
153 Active retrusive movement
First the horizontal overjet is measured in habitual occlusion with a ruler or sliding caliper. Then the patient is Instructed to “pull the lower jaw back” or -push the upper jaw forward” as far as possible. The read directly, although this is of no importance in making a differential diagnosis. Left: The chart entry is made in the usual manner. Values range from 0 to 2 mm.
154 Translation of the condyles during active jaw opening
A qualitative evaluation of condylar translation can be made by palpation. Normally during jaw opening the condyles move only to the crest of the articular eminence. The mobility (✓), hypomobility (-), or hypermobility (+). Left: Example of chart notations using the corresponding symbols. Upon jaw opening, mobility of the right condyle was normal while there was hypermobility of the left condyle.
155 Translation of the condyles during active protrusion
The extent of condylar translation during protrusive movement is also determined. A movement that stops just short of the crest of the but a condyle that passes beyond the eminence is considered hypermobile. If the condyle moves out of the fossa only slightly or not at all, it is hypomobile.
Left: This entry in the examination form indicates that the right condyle was hypomobile and the left had normal mobility. This test replaces the documentation of deviation and deflection.
156 Further passive jaw opening beyond active opening
Passive jaw opening is usually executed with both hands. The index or middle fingers are placed on the upper premolars and the thumbs on the lower incisal edges. The patient opens the mouth as far as possible and at the end of the active movement the clinician assists further opening. The amount of passive movement is evaluated. If the one-handed technique is used the distance can be measured with the other hand.
Left: Chart entry.
157 Section of examination form dealing with passive jaw opening
If there is pain upon passive jaw opening, the amount of movement is written in red. Then the amount of force needed to elicit pain is indicated by means of red plus signs (+, ++, +++) written in the box for the painful side. The endfeel is recorded only when jaw opening is painless, otherwise the patient will reflexively tense the muscles.
158 Limited jaw opening resulting from skin changes in scleroderma
Left: In a patient with scleroderma, taut cords form In the skin during passive jaw opening and the end-feel is “too hard.” Right: Sclerosing of the skin causes typical limitation of jaw opening to 30-35 mm. This must not be confused with a nonreducing disk displacement.
159 A “too soft endfeel” with passive jaw opening
Left An endfeel that is “too soft” accompanied by condylar hypermobility. The length of the jaw-closing muscles limits opening movements when there is lengthening or overstretching of the capsule and ligaments. Rigbt: A “too soft” endfeel accompanied by reduction of jaw opening. Tensed or shortened elevator muscles are limiting the extent of jaw opening.
160 An endfeel that is “too hard” and “rebounding”
Left: A “too hard” endfeel with restricted jaw opening. The shortened capsule and ligaments are limiting jaw opening.
Center: MRI image of the nonreducing disk displacement at maximal jaw opening.
Right: Rebounding endfeel at the end of a restricted jaw-opening movement. The nonreducing anterior disk displacement limits jaw opening.
Differential Diagnosis of Restricted Movement
Nonpainful limitations of movement can be differentiated only by evaluating the endfeel after passive movement. The ability to make an exact determination of the endfeel requires practice and a little experience. This is the only method by which structural causes of restricted movement can be discovered. The elicited endfeel is merely verified secondarily through other methods such as the joint play technique, radiographs, or MRI. These, however, are not indicated for use as primary differential diagnostic procedures. During the passive jaw-opening procedure 92.5% of patients report a drawing sensation in the preauricular region (Hesse 1996). This false perception can be accounted for by the stretching of the joint capsule and the lateral ligament.
If passive jaw opening causes the patient pain, the endfeel cannot be used to aid in making a differential diagnosis of limited movement. Therefore, when the signs and symptoms include the combination “pain and restricted movement,” the pain must be treated first before an adequate differential diagnosis of the restricted movement can be made.
161 Examination sequence when there is a nonpainful limitation of jaw opening
The diagram shows the sequence in which the examination techniques are to be carried out. In a patient with scleroderma tight cords appear in the skin during passive jaw opening (Fig. 158). In these cases the dentist can prescribe mobilization exercises (“jawsercises,” Korn 1994) and refer the patient to a dermatologist if the disease is not already being treated. In patients with restricted jaw opening the endfeel may assume one of four characteristics: too soft, too hard, rebounding, or bony.
