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. 2020 Sep 30;13:2413–2421. doi: 10.2147/JPR.S268114

Table 2.

Overlapping Primary Studies and Main Results for Each Intervention

Intervention Number of SRs Number of Included RCTs Number of Overlapping RCTs Main Results
BTX-A 4 5 2 Compared to placebo, BTX-A presented:

  • No difference in pain relief at chewing VAS [MD −1.1 95% CI −3.37 to 1.17, one RCT, 20 participants] and at rest [MD −0.5 95% CI −3.01 to 2.0; one RCT, 20 participants], after 6 months

  • No difference in the subjective questionnaire of symptoms [MD −0.78 95% CI −1.73 to 0.17; one RCT, 12 participants], after 3 months

  • Significant reduction in bruxism frequency during sleep [MD 2.70 95% CI 3.92 to 1.66; one RCT, 12 participants], after 3 months

  • No adverse events [one RCT, 12 participants]

Compared to conventional treatment (behavioral therapy, occlusal splints,
drugs), BTX-A presented:

  • Significant pain reduction, after 6 and 12 months [MD −1.9 95% CI −2.25 to −1.55; one RCT, 50 participants]

Comparing different BoNT-A injection muscles (masseter alone versus masseter and temporalis):

  • No difference in morning jaw stiffness [MD −10.00 95% CI −24.99 to 4.99; one RCT, 24 participants] and subjective bruxism event [RR 0.75 95% CI 0.17 to 3.33; one RCT, 24 participants], after 1 month

Overall methodological quality: unclear to low risk of bias
Occlusal splint 2 14 0 Compared with palatal splint, occlusal splint presented:

  • No difference in arousal index, after 2 to 4 weeks of treatment [Meta-analysis of 2 RCTs: MD 1.22 95% CI −3.61 to 6.05; 30 participants]

  • No difference in the number of bruxism episodes per hour sleep, after 2 to 4 weeks of treatment [MD 0.54 95% CI 0.95 to 12.93; one RCT, 21 participants]

Compared with TENS, occlusal splint presented:

  • No difference in TMJ clicks during oral opening and closing, after 45 days of treatment [RR 0.60 95% CI 0.19 to 1.92; one RCT, 11 participants]

Compared with MAD free, occlusal splint presented:

  • Significantly higher proportion of preference reported by participants, after 2 weeks of treatment (12/13 versus 1/13 participants: one RCT)

Compared with muscle massage, occlusal splints + massage presented:

  • Reduction in the intensity of bruxism signs and symptoms [MD 21.33 95% CI 5.52 to 37.14; one RCT, 30 participants]

Overall methodological quality: unclear to low risk of bias
Biofeedback therapy 2 10 3 Compared to an inactive control, CES presented:

  • No difference in the number of painful muscles, self-reported pain, muscle tension, maximum pain-free jaw opening (no numerical data)

  • No difference in bruxism frequency during sleep [Meta-analysis of 3 RCTs: MD −5.05 95% CI −10.71 to 0.62; 54 participants], after 6-week treatment

Overall methodological quality: unclear to high risk of bias
Certainty of evidence: low to moderate
Drug therapy 1 7 0 Compared with placebo, the following drugs showed:
Amitriptyline:

  • No difference in pain reduction [Meta-analysis of 2 RCTs: MD −0.64, 95% CI −1.72 to 0.45; 20 participants] and in sleep duration [MD 25.37, 95% CI −9.12 to 59.86; 20 participants], after 3 to 7 days of treatment

  • Adverse events: 9 participants reported at least one: difficulty in waking in the morning, insomnia, xerostomia, irritability, increased clenching. In the placebo group, 2 participants reported neck stiffness and shoulder pain.

Bromocriptine:

  • No difference in bruxism episodes per hour, after 4 days of treatment [MD 0.60 95% CI −2.93 to 4.13; one RCT; 7 participants]

Clonidine:

  • No difference in bruxism episodes per hour, after 4 days of treatment [MD −2.41 95% CI −4.84 to 0.02; one RCT; 25 participants]

  • Adverse events: No difference [0.18 95% CI 0.03 to 1.09; one RCT; 25 participants]

Propranolol:

  • No difference in bruxism episodes per hour [MD 1.16 95% CI −1.89 to 4.21; one RCT; 25 participants]

Levodopa:

  • No difference in bruxism episodes per hour [MD −1.47 95% CI −3.64 to 0.70; one RCT; 10 participants]

Overall methodological quality: unclear to low risk of bias

Abbreviations: BTX-A, botulinum toxin type A; SR, systematic review; MD, mean difference; 95% CI, 95% confidence interval; RR, relative risk; TENS, transcutaneous electric nerve stimulation; TMJ, temporomandibular joint; MAD, mandibular advancement device; CES, contingent electrical stimulation.