Contraindications for the use of Myomonitor Dental TENS

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Ultra low frequency Dental TENS (ULF TENS) has been found to be clinically safe and effective in the treatment of masticatory dysfunctions, hypertonic (tight) muscles as well as temporomandibular joint derangement problems related to TMD.  Dentists who use ultra low frequency Dental TENS should recognize that there are manufacturers recommendations for its use as well as some contraindications.

The main purpose for ULF TENS is to help the dentist determine a more optimal mandibular jaw position when recording a physiologic maxillo-mandibular inter occlusal jaw registration.  Having the spastic muscles relaxed prior to recording a bite registration is therapeutically and clinically beneficial rather than trying to record a bite registration with hyperactive and strained muscles.

Indications for use of ULF Dental TENS in Dentistry:

  1. To treat temporomandibular joint (TMD) dysfunctions and associated pain.
  2. To relieve symptoms associated with muscle spasm.
  3. To relax muscles and establish a physiologic occlusion.
  4. To take an occlusal registration.
  5. To take denture impressions.
  6. To increase local blood circulation
  7. To maintain or increase mandibular range of motion.


The only contraindications and precautions when Dental TENS should not be used would be in patients who have cardiac demand pacemakers, cancerous lesions, malignant tumors, pregnancy (warning), should not be placed over the carotid sinus nerves, not to be used over infected or swollen areas of the skin and should be kept out of the reach of children.

The following are some manufacturers contraindications for use of Dental TENS:

  1. Powered muscle stimulators should not be used on patients with cardiac demand pacemakers. Prior to treatment of pacemaker patient with the J5 consult primary care physician should be consulted.
  2. EMS (Electrical Muscle Stimulation) devices such as the J5 should not be used over, or in proximity to cancerous lesions.


  1. Safety has not been established for use of EMS devices during pregnancy.
  2. Adequate precautions should be taken when using EMS on patients with suspected or diagnosed epilepsy or heart problems.
  3. EMS devices should not be applied transcerebally.
  4. Stimulating electrodes should not be placed over the carotid sinus nerves, especially in patients with a known sensitivity to the carotid sinus reflex.
  5. CAUTION should be used in the transthoracic application of EMS devices in that the introduction of electrical current into the heart may cause arrhythmias.
  6. Severe spasm of the laryngeal and pharyngeal muscles may occur when the electrodes are positioned over the neck or mouth.  The contractions may be strong enough to close the airway or cause difficulty in breathing.
  7. Caution:  Electrodes should not be placed over the carotid nerve plexus.
  8. EMS devices should not be used over swollen, infected, or inflamed areas of skin eruptions, e.g. phlebitis, thrombo phlebitis, varicose veins.
  9. EMS devices should be kept out of the reach of children.


  1. Some individuals may experience skin irritation or hypersensitivity due to the electrode adhesive or conductive medium or due to the electrical stimulation.  The irritation can usually be reduced by use of an alternate conductive medium or alternate electrode placement.  If a strong stinging feeling is experienced at an electrode site, check electrode and replace if necessary.  Avoid placing electrodes over areas where the skin is red or inflamed.
  2. In some individuals with headaches or vasular origin, EMG may induce or aggravate the pain (e.g. temporal arteritis).  The doctor’s judgment should be used as to whether or not to continue.
  3. If an individual suffers from senility, psychological or motor limitations, precautions should be exercised to insure that the EMS units are used properly to insure the patient’s safety.
  4. Precautions should be observed in the presence of the following:
    • When there is a tendency to hemorrhage following acute trauma or fracture.
    • Following recent surgical procedures when muscle contraction may disrupt the healing process.
    • Application of EMS over the menstruating uterus.
    • Where sensory nerve damage is present by a loss of normal skin sensation.

Technical Information of J5 (Myomonitor) Dental TENS:

  • Output Voltage of the J5 Myomonitor Dental TENS (maximum – each side), -75 +/- 10 volts.  (These are absolute values and do not represent typical levels of patient stimulation).
  • Output current is -18 mA to -24 mA. (Typical output current is -8 to -12 mA).
  • Interval pulse is 1.5 +/- -0.15 seconds


Its been my observation with those who have chronic hypertonic muscles (tense patients) may experience discomfort during low frequency Dental TENSing.  This would not be unusual for those individuals who have long history of chronic tight muscles.  J5 Dental TENS can be very annoying to some, due to their resistance to muscle splinting while trying to relax the muscles.  While low frequency TENS stimulation can be annoying to some it is one of the clear clinical indicators that these individuals of tense (tight) hyperactive muscles which is pathologic (not normal).

Spending the extra time to inform the patient ahead of time of this can alleviate surprises of what muscle relaxation is about. If the patient who has chronic tense muscles tries to resist the low frequency pulse stimulation, naturally they may become more agitated.

For best TENSing results it is best to try to go with the flow of the pulse as best as possible.

TENSing is a different type of relaxation. Low frequency Dental TENs is a physiologic relaxation modality but for a few individuals it can be irritating to some patients, especially the “real chronic ones”.  Knowing what ultra low frequency TENS is about will help minimize any misunderstanding, anticipations and preconcieved ideas about muscle relaxation with ULF TENS.

ULF Dental TENS Safety:

Safety of TENS devices has been scrutinized by the medical community over the past 40 years. The scientific literature is unanimous in validating the safety of TENS devices. This is an excerpt from an FDA publication titled “An Introduction to Electrical Nerve Stimulation: TENS” dated August 1986, published by Center for Devices and Radiological Health branch of the FDA:

 “The approximately one hundred publications from the most recent years are virtually unanimous in TENS safety.  The notable exception is a necessary awareness of potential fetal stimulation during labor pain.  In all other aspects, Dental TENS risk is limited to minor and easily remedied skin irritations from electrodes and electrode gels in a rather small number of reported cases.”

The U.S. Food and Drug Administration has very specific guidelines for all manufacturers in listing of FDA’s  Indications. Contraindications, Warnings, Adverse Effects and Precautions (J5 Myo-monitor Operating Guide, 2015, pp 2-3).  “ Shorting out” or injuring the nervous system is not a listed adverse effect or precaution of TENS devices and can not be attributed to TENS therapy.

 One other issue, J4/BNS-40 are one of only few TENS devices that are equipped with a “Patient Fail-Safe Circuit”.  The delivery of current to the patient will be automatically interrupted if the Fail-Safe circuitry is activated.


J5 Myo-monitor Operating Guide, 454300-9 Revision C, Myotronics, Inc. Kent, Washington, U.S.A