Efficacy of aromatherapy on dental anxiety: A systematic review of randomised and quasi-randomised controlled trials

Objectives To evaluate the efficacy of aromatherapy on dental anxiety. Methods A detailed protocol was registered a priori (PROSPERO: CRD42019141093). PubMed, EMBASE, CDSR, CENTRAL, CNKI and grey literature databases were searched from inception to 10 January 2020. Randomised controlled trials (RCTs) and quasi-randomised controlled trials (CCTs) that examined the effects of aromatherapy on dental anxiety, compare to either negative control (i.e. no aromatherapy) or other positive control approaches (e.g. music), were included. The risk of bias of the selected studies was evaluated using the Cochrane Collaboration's tool and ROBINS-I, while the certainty of evidence was assessed using GRADE. A narrative synthesis was performed, rather than meta-analysis, due to the high level of heterogeneity across studies. Results Eleven RCTs and six CCTs were included. The risk of bias was identified as either high or unclear in RCTs, and moderate to serious in CCTs. Performance bias and detection bias were the most prevalent in RCTs, followed by selection bias and reporting bias. As to CCTs, greater risk of bias was found in the selection of participants into the study and in the measurement of outcomes. Based on the selected studies, the most commonly used aromatherapy for dental anxiety management was lavender fragrance, followed by orange. Compared to the negative control condition, aromatherapy might reduce the anxiety-related physiological parameters and psychometric rating, pain, and mood, alertness, and calmness compared to the negative control condition; and there might be no intergroup difference in such outcomes between aromatherapy and music. However, GRADEs of the relevant evidence were judged as low to very low. Conclusions Compared to the negative control condition, aromatherapy is more effective to reduce dental anxiety and has comparable effects on dental anxiety compared to music intervention; however, the certainty of evidence is relatively limited. Further high-quality randomised trials with robust study design and large sample size are warranted to confirm our findings and to confirm the role of aromatherapy in relieving dental anxiety.