Changes in active mouth opening following a single treatment of latent myofascial trigger points in the masseter muscle involving post-isometric relaxation or strain/counterstrain

PIR is effective in increasing the range of mandibular motion in patients with trigger points and increased masseter tension.

“The reports indicate the effectiveness of PIR in increasing the range of mandibular motion in patients treated due to the presence of trigger points and an increased tension of the masseter muscles [16].”

The results of the cited studies by Blanco et al. and Ibanez-Garcia et al. are consistent with each other despite different measurement tools.

“Despite the fact that the measurement tools used in the cited studies differ from those used in our report, the results of these researches are consistent with each other [16,17].”

Ibanez-Garcia et al. demonstrated significantly greater improvement in pain-free mandibular range of motion after using the modified MR method than after using the PIR intervention described by Blanco et al.

“However, it should be noted that Ibanez-Garcia et al. [17] demonstrated a significantly greater improvement in the pain-free mandibular range of motion after using the modified MR method than using the PIR intervention described by Blanco et al. [16].”

Blanco et al. conducted a study comparing the efficacy of PIR and positional release (strain/counterstrain) in the treatment of myofascial pain with latent myofascial trigger points in the masseter muscles.

“Blanco et al. [16] conducted a study comparing the efficacy of PIR and positional release (strain/counterstrain) in the treatment of myofascial pain, manifested by latent myofascial trigger points (MTrPs) and located in the masseter muscles.”

In Blanco et al.'s study, a significant increase in pain-free active mandibular range of motion was observed in subjects who underwent a single PIR procedure.

“A significant increase in the pain-free active mandibular range of motion was observed in subjects who underwent a single PIR procedure, while there was no significant change in the examined parameter in the group of subjects undergoing the positional release method.”

Reports on trunk and limbs soft-tissue therapy indicate a significant effect of PIR on minimization of pain and increasing range of motion in joints.

“These reports indicate a significant effect of PIR on the minimization of pain and increasing the range of motion in the joints [16,27,32,33,34], accompanied by a decrease in muscle electrical activity [35].”

In Blanco et al.'s study, there was no significant change in pain-free active mandibular range of motion in the group undergoing positional release.

“A significant increase in the pain-free active mandibular range of motion was observed in subjects who underwent a single PIR procedure, while there was no significant change in the examined parameter in the group of subjects undergoing the positional release method.”