OBJECTIVES: To assess the effects of pharmacological and non-pharmacological interventions for the management of gagging in people undergoing dental treatment.

SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the Cochrane Oral Health's Trials Register (to 18 March 2019), the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 2) in the Cochrane Library (searched 18 March 2019), MEDLINE Ovid (1946 to 18 March 2019), Embase Ovid (1980 to 18 March 2019), CINAHL EBSCO (1937 to 18 March 2019), AMED Ovid (1985 to 18 March 2019), and the proceedings of the International Association for Dental Research (IADR) online (2001 to 18 March 2019). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. We also conducted forwards citation searching on the included studies via Google Scholar. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA: We included randomised controlled trials (RCTs), involving people who were given a pharmacological or non-pharmacological intervention to manage gagging that interfered with dental treatment. We excluded quasi-RCTs. We excluded trials with participants who had central or peripheral nervous system disorders, who had oral lesions or were on systemic medications that might affect the gag sensation, or had undergone surgery which might alter anatomy permanently.

DATA COLLECTION AND ANALYSIS: We independently selected trials, extracted data, and assessed risk of bias. We followed Cochrane's statistical guidelines. We assessed the overall certainty of the evidence using GRADE.

MAIN RESULTS: We included four trials at unclear risk of bias with 328 participants (263 adults and 65 children who were four years or older), in which one trial compared acupuncture and acupressure (with thumb, device and sea band) at P6 (point located three-finger breadths below the wrist on the inner forearm in between the two tendons) to sham acupuncture and acupressure with and without sedation. One trial compared acupuncture at P6 point to sham acupuncture. These trials reported both completion of dental procedure and reduction in gagging (assessor and patient reported) as their outcomes. One cross-over and one split-mouth trial studied the effect of laser at P6 point compared to control. One trial reported reduction in gagging and another reported presence or absence of gagging during dental procedure. Acupuncture at P6 showed uncertain evidence regarding the successful completion of dental procedure (RR 1.78, 95% CI 1.05 to 3.01; two trials, 59 participants; very low-certainty evidence) and uncertain evidence regarding the reduction in gagging (RR 2.57, 95% CI 1.12 to 5.89; one trial, 26 participants; very low-certainty evidence) in comparison to sham acupuncture. Acupuncture at P6 with sedation did not show any difference when compared to sham acupuncture with sedation (RR 1.08, 95% CI 0.91 to 1.28; one trial, 34 participants; very low-certainty evidence). Acupressure using thumb pressure with or without sedation showed no clear difference in completing dental procedure (RR 0.96, 95% CI 0.84 to 1.10; one trial, 39 participants; very low-certainty evidence; and RR 0.85, 95% CI 0.50 to 1.46; one trial, 30 participants; very low-certainty evidence; respectively), or reduction in gagging (RR 1.06, 95% CI 0.92 to 1.23; one trial, 39 participants; very low-certainty evidence; and RR 0.92, 95% CI 0.60 to 1.41; one trial, 30 participants; very low-certainty evidence; respectively) when compared to sham acupressure with or without sedation. Acupressure at P6 with device showed uncertain evidence regarding the successful completion of dental procedure (RR 2.63, 95% CI 1.33 to 5.18; one trial, 34 participants; very low-certainty evidence) and uncertain evidence regarding the reduction in gagging (RR 3.94, 95% CI 1.63 to 9.53; one trial, 34 participants; very low-certainty evidence) when compared to sham acupressure. However, device combined with sedation showed no difference for either outcome (RR 1.16, 95% CI 0.90 to 1.48; one trial, 27 participants; very low-certainty evidence; and RR 1.26, 95% CI 0.93 to 1.69; one trial, 27 participants; very low-certainty evidence; respectively). Acupressure using a sea band with or without sedation showed no clear difference in completing dental procedure (RR 0.88, 95% CI 0.67 to 1.17; one trial, 21 participants; very low-certainty evidence; and RR 1.80, 95% CI 0.63 to 5.16; one trial, 19 participants; very low-certainty evidence; respectively), or reduction in gagging (RR 0.88, 95% CI 0.67 to 1.17; one trial, 21 participants; very low-certainty evidence; and RR 2.70, 95% CI 0.72 to 10.14; one trial, 19 participants; very low-certainty evidence; respectively) when compared to sham acupressure with or without sedation. Laser at P6 showed a difference in absence of gagging (odds ratio (OR) 86.33, 95% CI 29.41 to 253.45; one trial, 40 participants; very low-certainty evidence) and reduction in gagging (MD 1.80, 95% CI 1.53 to 2.07; one trial, 25 participants; very low-certainty evidence) during dental procedure when compared to dummy laser application. No noteworthy adverse effects were reported. For acupuncture at P6, the trial authors were unsure whether the reported adverse effects were due to participant anxiety or due to the intervention. None of the trials on acupressure or laser reported on this outcome. We did not find trials evaluating any other interventions used to manage gagging in people undergoing dental treatment.

OBJECTIVES: To assess the effects of interventions for the management of patients with taste disturbances.

SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 4 July 2017); the Cochrane Central Register of Controlled Trials (CENTRAL; 2017 Issue 6) in the Cochrane Library (searched 4 July 2017); MEDLINE Ovid (1946 to 4 July 2017); Embase Ovid (1980 to 4 July 2017); CINAHL EBSCO (1937 to 4 July 2017); and AMED Ovid (1985 to 4 July 2017). The US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for trials. Abstracts from scientific meetings and conferences were searched on 25 September 2017. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA: We included all randomised controlled trials (RCTs) comparing any pharmacological agent with a control intervention or any non-pharmacological agent with a control intervention. We also included cross-over trials in the review.

DATA COLLECTION AND ANALYSIS: Two pairs of review authors independently, and in duplicate, assessed the quality of trials and extracted data. Wherever possible, we contacted trial authors for additional information. We collected adverse events information from the trials.

MAIN RESULTS: We included 10 trials (581 participants), nine of which we were able to include in the quantitative analyses (566 participants). We assessed three trials (30%) as having a low risk of bias, four trials (40%) at high risk of bias and three trials (30%) as having an unclear risk of bias. We only included studies on taste disorders in this review that were either idiopathic, or resulting from zinc deficiency or chronic renal failure.Of these, nine trials with 544 people compared zinc supplements to placebo for patients with taste disorders. The participants in two trials were children and adolescents with respective mean ages of 10 and 11.2 years and the other seven trials had adult participants. Out of these nine, two trials assessed the patient-reported outcome for improvement in taste acuity using zinc supplements (risk ratio (RR) 1.40, 95% confidence interval (CI) 0.94 to 2.09; 119 participants, very low-quality evidence). We meta-analysed for taste acuity improvement using objective outcome (continuous data) in idiopathic and zinc-deficient taste disorder patients (standardised mean difference (SMD) 0.44, 95% CI 0.23 to 0.65; 366 participants, three trials, very low-quality evidence). We also analysed one cross-over trial separately using the first half of the results for taste detection (mean difference (MD) 2.50, 95% CI 0.93 to 4.07; 14 participants, very low-quality evidence), and taste recognition (MD 3.00, 95% CI 0.66 to 5.34; 14 participants, very low-quality evidence). We meta-analysed taste acuity improvement using objective outcome (dichotomous data) in idiopathic and zinc-deficient taste disorder patients (RR 1.42, 95% 1.09 to 1.84; 292 participants, two trials, very low-quality evidence). Out of the nine trials using zinc supplementation, four reported adverse events like eczema, nausea, abdominal pain, diarrhoea, constipation, decrease in blood iron, increase in blood alkaline phosphatase, and minor increase in blood triglycerides.One trial tested taste discrimination using acupuncture (MD 2.80, 95% CI -1.18 to 6.78; 37 participants, very low-quality evidence). No adverse events were reported in the acupuncture trial.None of the included trials could be included in the meta-analysis for health-related quality of life in taste disorder patients.