Tooth extraction is a traumatic event, albeit a necessary procedure, used to treat patients with severe dental caries or malocclusion. The physical forces required to perform a tooth extraction often exceed forces the body can accommodate without an adverse response. Rather than causing fracture or tears, the strain that is introduced into the cranial musculature and sutures can lead to misalignment of the cranial bone articulations
11—a misalignment called cranial somatic dysfunction. Somatic dysfunction is, by definition, a condition in which there is “[i]mpaired or altered function of related components of the somatic (body framework) system: skeletal, arthrodial and myofascial structures, and related vascular, lymphatic, and neural elements.”
12
The cranium has unique palpable anatomic and physiologic characteristics that become altered when somatic dysfunction occurs. Normally, the brain and spinal cord, cerebrospinal fluid, cranial and spinal dural membranes, cranial bones, and sacrum have coordinated functions and a movement pattern called the primary respiratory mechanism.
12 The motion that can be palpated is called the cranial rhythmic impulse.
12 Each component of the primary respiratory mechanism must be present and without somatic dysfunction for optimum function, which includes unobstructed circulation of fluids and absence of dural and nociceptive afferent input. Palpation of the cranium for somatic dysfunction is taught at most colleges of osteopathic medicine and is used in practice by many osteopathic physicians.
William Garner Sutherland, DO, proposed a mechanism for the induction of cranial strain through dental extractions.
13 He theorized that the side-to-side leverage used to extract the tooth with forceps, combined with posterior occiput compression caused by the V-shaped headrest commonly used at the time, results in somatic dysfunction of the mandible, maxilla, sphenoid, and temporal bones. Although the V-shaped headrest is not commonly used in modern dentistry, the action used to extract a tooth has largely remained unchanged. The side-to-side leverage disrupts the alignment of the cranial bones and can lead to abnormal function of the muscles of mastication and strain in the dura mater. Both of these structures—the muscles and the dura—transmit painful stimuli when abnormal stressors, such as excessive stretch, are placed on them.
The particular cranial dysfunctions that are induced will vary depending on whether an upper or a lower molar was extracted. These dysfunctions can be anticipated by knowing how the cranial sutures are beveled. The following text describes the cranial strains that commonly occur. The description should not be viewed as the only cranial dysfunctions that may be present after dental extractions.
In an upper molar extraction, the maxilla is pulled inferiorly and laterally and, therefore, impinges upon the coronoid process of the mandible. These motions disrupt the normal alignment of the temporomandibular joint,
13 an arthrodial joint in which the mandible articulates with the temporal bone. The temporal bone then becomes compressed into the occiput at the occipitomastoid suture. Temporomandibular joint movements include depression or elevation of the jaw by opening or closing the mouth, as well as a protrusion and retrusion motion of the jaw.
8 Misalignment of the temporomandibular joint leads to restriction of motion, malocclusion, alteration of the tension of the mastication muscles, and subsequent head and neck pain.
14 The patient in the present case followed this pattern, with temporal bone somatic dysfunction and occipitomastoid suture compression (
Figure).
Lower molar extractions tend to compress the temporal bone at the mandibular articulation on the same side of the extraction. In a lower molar extraction, the side-to-side leverage pulls the opposite mandibular articulation inferiorly. Increased strain is induced in the sphenomandibular ligament, and the sphenoid bone is pulled inferiorly and laterally on the side opposite the extraction.
The sphenoid bone forms an anatomically significant part of the orbit, houses the cavernous sinus, and has foramina through which the orbital nerves, arteries, and veins pass. Alteration of the size or shape of the foramina can directly affect the structures that pass through them. The trigeminal nerve's 3 branches enter through the sphenoid—the ophthalmic nerve (V
1) via the supraorbital fissure, the maxillary nerve (V
2) via the foramen rotundum, and the mandibular nerve (V
3) via the foramen ovale.
6 Magoun
6 describes trigeminal neuralgia in predisposed patients after upper and lower dental extractions as a result of dysfunction of the temporal, sphenoid, maxilla, and mandible bones. He documents improvement in patient symptoms with the application of various cranial techniques to these areas.
6 Sphenoid strain through its effect on the orbit can also lead to dysfunctional movement of the extraocular muscles, many of which attach to the common annular tendon that is on the main body and lesser wings of the sphenoid bone.
13
Libin
15 proposed that the interjaw space between the maxilla and mandible bones be considered to function like a cranial suture. It is the goal of osteopathic medicine that this suture, like all other cranial sutures, have friction-free physiologic motion.
15 The physiologic motion of the cranium can be disrupted by dental malocclusion, incorrectly positioned teeth, and dental trauma. The motions of the mandible and maxilla are important to address—not only when the mouth is open, but also with closure of the mouth. If malocclusion is present, the cranial mechanism will be affected through articulation of the mandible with the temporal bones and, thereby, the sphenobasilar junction. Dental prostheses must be fitted and adjusted so as not to restrict motion—especially when extending across the midline of the face. Tight dentures, retainers, or night guards can be a cause of cranial dysfunction.
1
Although muscle dysfunction was not specifically addressed in the present case, the patient's pain was consistent with patterns of levator scapulae and trapezius trigger point pain. The patient described pain coming from the base of the skull and neck and radiating to the orbit and vertex and down to the right arm. A trigger point is defined as “a focus of hyperirritability in a tissue that, when compressed, is locally tender and … gives rise to referred pain and tenderness.”
16 A trigger point in the upper trapezius fibers refers pain around the side of the head into the orbit. Lower trapezius trigger points refer into the suprascapular area.
16 A trigger point in the levator scapulae radiates down the shoulder into the posterior arm
16—consistent with the patient's description of pain without tender points within the posterior arm. The muscular component of these symptoms could have arisen from increased muscle tension related to anxiety and pain during the tooth extraction, as well as the continued cranial dysfunction that went untreated for months. Evaluation of muscular somatic dysfunction or trigger points may assist in the management of this type of condition.
In the course of a 15-minute office visit, the movements of all aspects of the face and cranium cannot be palpated and evaluated. A focus on key areas of restriction, including the occipitomastoid suture, the occipitoatlantal joint, and the temporal bones, can provide the basis of a treatment plan. Addressing these key areas with OMT can lead to clinically significant improvement in patients' cranial motion and symptoms.