A Cochrane review [withdrawn from publication] included 6 studies with a total of 392 subjects. The intervention, occlusal adjustment (OA) is the selective adjustment of the biting surface of the teeth by grinding the enamel (outer layer of the tooth) so that the upper and lower teeth fit together (the inter-cuspal position) harmoniously. Symptom-based outcomes were extracted from trials on treatment. Data on incidence of symptoms were extracted from trials on prevention. Neither showed any difference between OA and control group. Beneficial effects on some outcomes cannot be excluded.
Comment: The quality of evidence is downgraded by imprecise results (few patients and wide confidence intervals), by inconsistency (heterogeneity in interventions and outcomes) and by indirectness (differences in studied patients: concerns of the validity and reliability of the diagnostic criteria used in the trials).