The difficulty in fully opening or closing your mouth after wisdom teeth removal is a common post-operative symptom known as trismus. This temporary condition is characterized by restricted jaw movement due to muscle stiffness and spasm. While uncomfortable, making eating or speaking a challenge, it is a normal and expected response to the surgical procedure. The stiffness is the body’s natural reaction to trauma and inflammation, which temporarily limits the function of the chewing muscles.
The Physiological Reasons for Jaw Stiffness
The primary cause of trismus is trauma to the muscles responsible for moving the jaw, known as the muscles of mastication. These muscles, particularly the masseter and temporalis, are often strained or bruised during the extraction process. The risk is higher with impacted lower wisdom teeth, as the surgeon may need to apply significant force or keep the mouth open for an extended period.
Another contributing factor is the local anesthetic injection, specifically the inferior alveolar nerve block. This injection is administered deep in the back of the mouth, often near the medial pterygoid muscle. If the needle irritates this muscle or the anesthetic solution causes localized inflammation, it can trigger a protective spasm. The body interprets this surgical manipulation as an injury, causing the muscles to reflexively tighten.
Post-operative swelling, or edema, also limits jaw mobility. As surrounding tissues swell in response to surgery, the physical bulk restricts the space and movement of the jaw joint and muscles. This generalized inflammation contributes to the feeling of tightness and inability to open the mouth normally. The combination of muscle strain, injection irritation, and swelling results in the restricted movement characteristic of trismus.
Recovery Timeline and Mobility Exercises
The stiffness from trismus typically peaks within the first two to three days following surgery, aligning with the maximum swelling period. For most patients, this limited jaw mobility begins to gradually resolve after the third day and should largely disappear within one to two weeks. Proactively managing the stiffness can help restore full function sooner.
Starting on the third day post-surgery, when initial swelling has begun to subside, applying moist heat to the jaw and cheek area can be beneficial. Using a warm, damp cloth or a heating pad for about 15 minutes per hour helps relax the tight jaw muscles and increase blood flow. This warmth prepares the muscles for gentle movement.
Once the acute pain subsides, usually 24 to 48 hours after the procedure, you can begin gentle, controlled jaw stretches. A simple exercise involves slowly opening your mouth as wide as possible without causing sharp pain and holding the stretch for several seconds. You can also perform lateral movements, slowly moving your jaw side-to-side, holding each position briefly.
For a slightly more involved stretch, you can use your fingers to assist the movement, known as passive stretching. Place one thumb on your upper front teeth and an index finger on your lower front teeth, then gently use your fingers to increase the opening slightly, without forcing it. Performing these exercises several times a day helps prevent scar tissue from forming and retrain the muscles. Maintaining a soft diet during this recovery period is advisable to minimize strain.
When to Contact Your Oral Surgeon
While trismus is a normal part of recovery, certain symptoms may indicate a complication requiring immediate attention from your oral surgeon. Report if your ability to open your mouth continues to worsen instead of gradually improving after the third or fourth day. A lack of improvement after one week, or any increase in stiffness beyond the expected peak, also warrants a call.
Look for signs of a developing infection, such as swelling that increases significantly after the third day, pus at the surgical site, or a severe foul odor. Uncontrolled or severe, throbbing pain not managed by prescribed medication is also a warning sign. Contact your surgeon right away if you develop a fever or experience persistent clicking, locking, or structural jaw joint pain that feels more than muscular.