This review found inconclusive and conflicting findings about the role of conscious sedation in the management of dental anxiety during third molar extraction surgery. Summary of the findings was limited by the lack of a of consistent, standardized outcome measures, thus preventing from drawing definitive conclusions.
Dental anxiety is a common aspect of oral-surgical procedures, and patients may benefit from the use of conscious sedation [10]. The advantages of conscious sedation may include lower patient anxiety [8, 19, 21, 23, 25], reduced post-surgical pain [27] increased patient and surgeon satisfaction [28], and inhibition of gag reflex [29]. In addition, it can be safely delivered in a non-operating room environment [30] and to patients with challenging behaviors as an alternative to general anesthesia [5]. Third molar extraction is a very common oral-surgical procedure that is very frequently associated with anxiety, thus presenting a large opportunity for the application of conscious sedation [4]. Although many studies have investigated this topic, the best approach remains to be established. Available literature shows large heterogeneity in selection of sedation drugs (or drugs combination), route of administration, anxiety evaluation scales and timing of assessment.
Patient-reported anxiety was the preferred outcome measure (despite being assessed using different scales), with six studies providing some indications from the comparison of different drugs [4, 8, 20–23] and nine studies reporting unclear or inconclusive findings [2, 9, 10, 12, 16, 18, 24–26. Lower cortisol levels were associated with midazolam [19] and remifentanil [17] when compared to placebo, while unclear findings were reported in the comparison of midazolam with N20/O2 [10].
The findings of this review should be interpreted within its limitations. First, the quality of included studies was unclear regarding some domains and some studies were at high risk of bias due to incorrect analysis of data from crossover design. Second, heterogeneity in comparisons, assessment and outcome measures prevented from pooling the findings of the included studies. Third, the focus on third molar extraction does not allow to generalize our considerations to other oral-surgical procedures.
Regarding the applicability of evidence, the use of pharmacological conscious sedation did not consistently show any advantages in the management of dental anxiety in third molar extraction surgery. There are still relevant questions that remain unanswered, including i) what the preferred drugs (and route of administration) should be, ii) what set of outcome measures should be included, and iii) when the outcome measures should be assessed. Of note, another open issue involves the investigation of sedation procedures separately from psychological and behavioral evaluations. A previous study showed a long-term reduction of dental fear in children thanks to behavioral and cognitive-behavioral interventions, while conscious sedation was less effective [31]. Furthermore, there was no strong evidence of anxiolytic effects of specific drugs such as opioids, which can lead to difficult social management if overprescribed. The justification for routine use of such drugs remains unclear, given the availability of less hazardous alternatives [32].
Although this review cannot draw definitive conclusions, the findings highlight some implications for future research on the topic. The definition of a minimum degree of standardization in study design can provide several benefits in term of comparability and generalizability of the findings. Of note, crossover design can be a valuable approach but requires appropriate implementation (i.e. randomization of sequences and adequate analysis of different-size sequences) [15]. A critical choice of investigated drugs could be advisable, since considerable information on safety and anxiolytic effectiveness of different molecules is available in literature. In our opinion, priority should be given to drugs who showed better anxiolytic effect and lower risk of adverse effects, easiness of use and higher patient satisfaction. An ordered sequence of possible comparisons may be defined for future investigations, thus leading to increased evidence of a low-level comparison before moving to the next-level comparison. In addition, a placebo-controlled arm should also be preferred to a no-intervention arm. A list of clinically relevant and validated outcome measures may be agreed upon a priori, in order to allow comparability and generalizability of the findings. Being dental anxiety a subjective state, outcome measures may include patient-reported anxiety (i.e. VAS, DAS) and objective parameters (i.e. stress hormones alteration), while external observer's assessment should be avoided (such studies were excluded from the review). The timing of anxiety evaluation should include baseline (i.e. few days before surgery, during the pre-operative visit), before-sedation and after-sedation (but before local anesthetic injection) because postoperative assessments are associated with a spontaneous anxiety reduction [33]. In addition, intra-operative data regarding not only standard physiological parameters (such as heart rate, blood pressure, peripheral capillary oxygen saturation) but also less used ones (such as the relative parasympathetic tone assessed by Analgesia/Nociception Index (ANI) should be collected to evaluate the overall patient’s perception of the surgical experience [34, 35].