it is a primary hyperalgesia with lowered pain threshold due to local factors such as stress, injury, infection etc.
- This may be due to:
1. distortion of blood vessels within the muscle or
2. forceful or sustained contraction repeatedly.
2. Muscle splinting pain:
it is defined as rigidity of the muscle occuring as a means of avoiding pain caused by movement of the part.
it is a reflex protective mechanism.
Splinting of masticatory muscle may occur as a protective mechanism in conditions such as toothache, overstressed teeth, effect of local anaesthetics, trauma etc.
3. Non-spastic myofacial pains:
There is no spasm and pain is the only complaint and this is generally referred to structures outside the muscle proper.
it may be due to atrophied muscle mass because of inactivity, illness or nutritional deficiency.
Zones of referred pain
- The masseter muscle pain refers to the ear, TMJ and the mandibular teeth.
- The temporalis refers to the temple, orbit and maxillary teeth.
- The medial pterygoid refers to the infra-auricular and post-mandibular area.
- The lateral pterygoid always refers its pain to the TMJ.
- Myofacial Pain Dysfunction Syndrome (Mpds)
- Muscular Disorders (Myofascial Pain Disorders) are the most common cause of TMJ pain associated with masticatory muscles.
- Common etiologies include:
1. Many patient with “high stress level”
2. Poor habits including gum chewing, bruxism, hard candy chewing
3. Poor dentition
- Its treatment includes 4 phases of therapy which includes muscle exercises and drugs involving NSAIDs and muscle relaxants.
- A bite appliance is also worn by the patient in the further stages to ‘splint’ the muscle movement.
- It is a condition wherein fibrous tissue and heterotropic bone forms within the interstitial tissue of muscle, as well as in associated tendons or ligaments.
- It is of two types: localized and generalized.
Localized myositis ossificans:
It is caused by trauma or heavy muscular strains or by metaplasia of pluripotential intermuscular cnnective tissue.
- The affected site remains swollen and tender, and the overlying skin may be red and inflamed.
- There may present a difficulty in the opening of the mouth.
- management is done by giving sufficient rest to the muscle and excision of the involved muscle after the process has stopped.
Generalized myositis ossificans:
- In this, formation of bone in tendons and fascia occurs along with subsequent replacement of muscle mass by the bony tissue.
- The masseter muscle is the most frequently involved.
- It usually occurs in children less than 6 years of age.
- It shows an evidence of dense osseous structures in the greater part or whole of the muscle.
- There is a gradual increase in stiffness and limitation in the motion of masticatory muscles. Ultimately, the entire muscle may get transformed into bone resulting in no movement.
Management: there is no specific treatment. The muscles involved are to be excised.