This survey sought to profile RA practice within a group of RA licensed Brazilian dentists who were mostly specialists, primarily focused on treatment of adults, and who for the most part practiced RA “sometimes”. According to our results, the dentists’ opinions were strongly related to details of their practices.
The practice of RA determined the favorability of opinions about this kind of sedation. Agreeing that attitudes and beliefs were predictors of the behavior ‘intention to provide RA’ , this study showed that a higher frequency of RA practice positively influenced dentists’ favorable opinions.
Most of the respondents reported they attended a training course in order to offer patients a choice for dental anxiety control. The most cited indications for RA were fearful and/or anxious patients, but the only indications that were significantly associated with RA practice after bivariate analysis were recommending RA for patients with certain mental or physical deficiencies. As these kinds of deficiencies are easily identifiable, we suspect this group of dentists do not actually use any systematic strategy to diagnose dentally anxious patients, and so are unable to recognize a patient with low to moderate anxiety. Possibly only patients who clearly demonstrated their anxiety would be offered RA. This suspicion is also supported by other studies  which found that dental anxiety level is a good predictor of referral for sedation; that is, highly anxious patients were more likely to be referred for sedation.
We did not find any differences in RA practice regarding its use in adults or children. On the contrary, surveys in other countries have shown that pediatric dentists are the specialists who use RA the most [12–14], and this modality is very popular among them [15, 16]. Thus, there is a trend for expansion of RA into other specialties that treat adults [17–19]. The American Dental Association advocates that an RA course should be a minimum of 14 hours, completed as a part of the predoctoral dental education program or in a postdoctoral continuing education competency course . In addition, a group of Canadian dentists believe RA should be included in the treatments that a licensed general practitioner can provide .
In this study, the practice of RA was significantly associated with the region of practice and the acquisition of the equipment. First, dentists practicing RA are concentrated in the South and Southeast Brazil, raising the prospect of an existing tendency for polarization in RA practice, perhaps because most of the qualified dentists live in these regions, and they are located where there are more RA training courses. Second, those who acquired the equipment were more easily able to practice RA, according to another study conducted in Northern Ireland , where those dentists that did not have RA equipment available in their practice were less likely to offer RA for pediatric extractions.
Respondents in this study generally agreed that RA has positive aspects, including its effectiveness, and satisfaction from both patients and professionals. Literature on the use of RA during dental treatment reports its usefulness in both children  and adults [18, 19]. The majority of a sample of 100 Italian preschool children appreciated RA and would like to have it offered again in their next sessions . Participants in this study reported one of the disadvantages of RA is that its acceptance by professionals and patients depends on cultural aspects and costs. In fact, nitrous oxide is one of the least accepted techniques by Kuwaiti parents, because the use of pharmacological techniques can be perceived as risky in that culture . Regarding the costs of RA, it is less expensive than general anesthesia  and probably other multidrug sedation, but carries an initial charge for the dentist to purchase the equipment.
Interestingly, respondents were unaware of the occupational risks of nitrous oxide. According to the literature, this is one of the most commented on points related to RA that limits its use ; chronic exposure to high levels of ambient nitrous oxide presents health hazards for dental personnel and patients which can have reproductive, hematologic, immunologic, neurologic, hepatic, and renal impacts . Occupational exposure to nitrous oxide can be controlled by effective vacuum gas-scavenging systems included in RA equipments, as well as by good work practices such as appropriate mask size selection and mask adjustment, minimal talking and mouth breathing by the patient .
In Brazil, one study showed that 93.7% of anesthesiologists surveyed disagreed that licensed dentists are adequately prepared to provide RA after the 96-hr training course required by the BCD . However, this understanding of anesthesiologists’ opposition was not a clear barrier to RA practice among Brazilian respondents, since only about half the respondents agreed that anesthesiologists’ contrary opinion on RA should limit its use by dentists. Moreover, a recent trial (ENIGMA trial) performed with anesthesiologists about the usage of nitrous oxide for general anesthesia were reported in three studies showing both positive  and negative [29, 30] recommendations in different situations.
In general, the sum of the scores reached by the respondents in our study represented an average level; that is, dentists in this study did not show the most positive opinions about RA. In another study , the level of knowledge about sedation was directly proportional to being in favor of its use and to the notion of associated risks. Perhaps more extensive practice with the RA technique during the training course could help dentists feel more secure about this sedation procedure, and have more positive opinions about it. Otherwise, it was reported that dentists’ perceptions of nitrous oxide inhalation sedation were generally less enthusiastic than those of patients and caregivers .
We recognize that this study as a survey had a major limitation in the coverage and non-response rate. Although we sent the questionnaire to all RA licensed dentists with available electronic mail, our response rate did not reach 50% of the study population. This response rate could be considered low for a survey targeting RA licensed dentists working in the whole country, but this is expected in electronically mailed questionnaires . There have been other studies with a similar purpose which had low response rates of 47%  and 16% . We understand that, as in another study with Brazilian health professionals , factors influencing response rates might include an unwillingness to participate or lack of interest in the subject. Also, we did not include dentists who attended a RA course but did not ask for their BCD license. In fact, the interpretation of the results should be viewed with caution because they primarily represent opinion rather than generalizable conclusions, as stated in another opinion study of professionals .