Table 4 Technical characteristics pertaining to the included papers

Liu et al. [45]

A longitudinal study with three measurement points (T0, T1, T2).

- MMA

- Parafunctional habits

- OBC

- DC/TMD Axis II

- sEMG

Not specified

- Temporalis muscle activity increased significantly between T0 and T1 (P < 0.05).

- At MVC, the activities of the TA and SCM at T1 were significantly higher than those of T0 (P < 0.05)

- OBC scores decreased greatly at the initial phase but then show a minor increase at further followup.

Manfrendini et al. [46]

Retrospective

- MMA during sleep

- sEMG.

Not specified

- Wearing the retainers did not significantly affect the sMMA variables.

Nota et al. [47]

Longitudinal study with three measurement points (T0, T1, T2).

- Mandibular elevator muscles activity

- pain on palpation

- sEMG

- RDC/TMD

Angle’s Class I malocclusion with crowding.

- The sEMG activity of masseter muscles at mandibular rest position showed a statistically significant reduction at T1 but returned to baseline levels at T2.

- No changes were noted for sEMG activity at clenching position

- At T0, pain was noted in 12.5% of the individuals which increased to 25% at T1.

Paes et al. [48]

Preliminary longitudinal study over an 8-month follow-up period.

- Biting force

- Myoelectric activity of the superficial masseter and anterior temporal muscles.

- Surface Electromyography

Angle’s Class I and Class II malocclusion.

- sEMG increased to approximately 30% for RMS value at p = 0.001.

- Bite force significantly reduced to < 20% at p < 0.05.

- Clenching of the teeth were reported in higher percentages.

Pittar et al. [49]

Prospective

- MMA,

- OD and

- TMD symptoms in adults with different levels of self-reported oral parafunction.

-OBC for parafunctional habit

- DC/TMD

- Wireless EMG

- Individuals reported with parafunctional habits

- A decreased MMA was noted with a reduction in mean contraction episode amplitude at p = 0.003.

- OD was increased at p = 0.048, particularly in high PFA subjects.

- TMD symptoms were present throughout the evaluation phase in both groups

Tran et al. [50]

Multi-site prospective study with follow up of four weeks

(

- Tooth pain

- Masticatory muscle soreness

- Pressure pain thresholds

- DC/TMD

- VAS (100 mm guage)

- Class I and Class II malocclusion

- Muscle soreness was found in all phases, though the dummy phase showed significantly greater soreness than active phase.

- Pain was present only in the first few days.

Pain was significantly correlated with trait anxiety (r = 0.423; p = 0.008)