Sir, the authors have considered the letters the journal has received in response to our article 'An intraoral device for weight loss: initial clinical findings' (Br Dent J 2021; doi: 10.1038/s41415-021-3081-1) and the responses are below.

In response to the critical review (Opinion paper), we feel that the points raised are already covered in the responses below and as such we do not feel any further response is either needed or would be helpful.1

We thank you for the concerns raised and your interest in our research. Observational studies are better suited to evaluate the incidence of adverse events of interventions because they have less strict inclusion and exclusion criteria, which allow a broader spectrum of the target population to be included. While RCTs are usually the best option to test efficacy (the effect of the intervention under ideal conditions), observational studies are a valuable option to evaluate effectiveness (the effect of an intervention in real life). The current study was considered as an observational study as it was primarily conducted to both validate and test the tolerability of the device in healthy individuals and therefore we believe the STROBE guidelines to be appropriate. In addition, the results as reported also conform to the CONSORT guidelines as one patient was lost to follow-up and the data for all the remaining patients in the trial are reported. A patient flow diagram would add no additional information given the small number of participants.

In total, 28 obese patients volunteered for the study; however, only seven participants fulfilled the study's inclusion criteria. Initially, we had planned to recruit ten participants for the study, but unfortunately, funding limitations meant that we had to stop the study after seven participants had been recruited. We have reported the data of all the seven participants who participated in the trial and have updated the final number of participants in the trial registry (ANZCTR).

With respect to the comment regarding difficulty in interpreting values of items in Table 2, please see the following section in the manuscript:

'the comfort and tolerability of the device were measured using a self-administered questionnaire using a Likert scale (1 = never; 2 = hardly ever; 3 = occasionally; 4 = fairly often; 5 = very often). The quality of life (QoL) was measured using an impact of weight and QoL during review appointments at baseline, 1, 7 and 14 days, and 14 days post-device removal. The participants ranked their QoL using a Likert scale questionnaire (5 = never true; 4 = rarely true; 3 = sometimes true; 2 = usually true; 1 = always true).'

The authors hope this addresses all your concerns.