Clinical tips for safe and effective root canal treatment under intravenous sedation with midazolam

Dental anxiety is considered a significant barrier to many patients seeking dental treatment,^1,2 including those who are fit and well, medically compromised, or special care patients.³ Root canal treatment (RCT) has been reported by patients to cause them the most anxiety,⁴ which may also increase pain intensity.⁴ Conscious sedation techniques can be used to help reduce the patient's anxiety while delivering safe dental treatment.⁵

The Intercollegiate Advisory Committee for Sedation in Dentistry (IACSD) defines conscious sedation as a ‘technique in which the use of a drug or drugs produces a state of depression of the central nervous system enabling treatment to be carried out, but during which verbal contact with the patient is maintained throughout the period of sedation.’⁶ All conscious sedation techniques should be administrated by qualified medical or dental care providers with an accredited certification to perform conscious sedation.⁶

In the UK, midazolam is most commonly administered for intravenous (IV) sedation by dentists. Midazolam works as an anxiolytic and muscle relaxant and attenuates the gag reflex. It helps in providing RCT for anxious and special care patients.⁴ However, because patients are consciously sedated and their muscles are relaxed, RCT under IV sedation with midazolam should be delivered with caution in order to provide safe treatment and avoid other complications.

This article provides clinical tips to help provide safe RCT under IV sedation with midazolam for novice sedationists or endodontists who perform RCT only, albeit under IV sedation.

Pre-operative instructions for dental treatment under IV sedation

Anxious patients are sometimes unable to retain pre-operative verbal instructions related to pain management or dental treatment owing to their anxiety levels.⁷ Therefore, it is important to follow current guidance and undertake a separate assessment visit. In some cases, it is not possible to assess whether the tooth is restorable or if it needs to be extracted until the existing restoration and/or caries have been removed. However, this is difficult to discuss with patients when they are receiving dental treatment under IV sedation, thus the written consent form should include all treatment outcomes as well as significant or unavoidable risks, such as swelling, infection, pain, discomfort, and the possibility of dental extraction for an unrestorable tooth.

On the day of the dental procedure under IV sedation, the written consent form should be signed by the patient and dentist. The patient should also bring a family member or friend for support and to help with the consent process, and for the journey home. Patients must sign the consent form when they can understand, weigh up and retain the information long enough to make the decision, and then articulate the decision about the dental treatment.⁸

Pre-IV sedation measures

The patient's baseline blood pressure, heart rate and oxygen saturation should be measured during the sedation suitability assessment. The patient should also be asked when they last ate, which is important for preventing any hypoglycaemic event. When a patient has not eaten, it is suggested that they be given a glucose drink, as conscious sedation masks signs of a hypoglycaemic episode.⁹ Fit and well patients should be instructed to have a light breakfast before a morning appointment or a light lunch before an afternoon appointment. Patients should be advised to avoid a heavy meal before having treatment under IV sedation to reduce risk of reflux and inhalation of gastric contents.

Moreover, it is important to check that the patient takes their normal medication as treatment under IV sedation does not routinely require stopping any medication. A responsible adult escort should also accompany the patient receiving dental treatment under IV sedation to their appointment to ensure safe discharge.⁷ It is also crucial to make sure that the patient does not do any of the activities listed in Table 1.

No dental treatment, such as RCT, should be started under IV sedation unless the patient has provided written, informed consent.⁷ The consent form should include the dental treatment plan (e.g. number and type of tooth), the purpose of RCT under IV sedation (e.g. dental anxiety and to deliver effective and safe RCT), any significant or unavoidable risks (e.g. unsuccessful RCT and the possibility of dental extraction, pain, discomfort, bleeding, swelling, and infection), costs of the treatment, dental care provider's name, position and signature, patient's name and signature and date confirming the planned dental treatment. This is important because no decision or change to the treatment plan (e.g. RCT versus dental extraction) can be made once RCT has commenced under IV sedation (Table 2). This is because Mental Capacity Act necessitates that the patients should fulfil the four criteria of having the mental capacity (e.g. understand, weigh up and retain the information and be able to communicate), and these are altered temporarily with IV sedation.⁸

Labelling the IV sedation drugs and irrigant solution(s)

IV sedation drugs should be labelled before any dental treatment under IV sedation, including labelling the irrigant solutions (i.e. sodium hypochlorite (NaOCl) and ethylenediaminetetra-acetic acid (EDTA)) to prevent injecting the irrigant solutions into the bloodstream (Figure 1). Therefore, having two separate kits, one for IV sedation drugs and another for the RCT irrigant solutions, helps to avoid such a serious event (Figure 2).¹⁰ Different syringe sizes using colour-coded tips will remind busy clinicians during treatment about the content of the syringes. Lastly, it is safe practice to consider treatment in two different stages: sedation and RCT.

Local anaesthesia under IV sedation

Various difficulties may be encountered during treatment after midazolam administration. Providing local anaesthetic can be challenging because the patient's muscles are relaxed and they may find keeping their mouth open difficult. Additionally, some patients may have a short window for the midazolam action, and further midazolam titration is then required. Local anaesthesia should be given as soon as the patient starts to relax after the first increment of the IV sedative drug because the patient will have minimum body movement.¹¹ This usually occurs after 5–7 minutes with a dose of 5–7 mg of IV midazolam, but varies between patients. It is essential to perform the dental treatment as quickly and efficiently as possible during the sedation window to avoid the sedative wearing off.

The importance of a mouth prop during IV sedation

Since the patient's muscles are relaxed owing to the effect of IV sedation drugs, there may be frequent closure of the mouth during treatment, thus making treatment challenging or even impossible. Mouth props are very useful to overcome this difficulty, as they help to keep the sedated patient's mouth open. It is essential to select the most appropriately sized mouth prop during IV sedation to avoid temporomandibular joint (TMJ) dislocation.¹² Moreover, it is advised to tie the mouth prop with a metal chain or dental floss for easier retrieval. Use of a mouth prop during RCT under IV sedation also helps to improve access and avoid sudden mouth closure, which could lead to mishaps, such as perforation during access cavity preparation or root canal instrument fracture.¹³

Rubber dam and the safety of treatment under IV sedation

All RCT procedures should be performed using a rubber dam to protect the airway from instruments, materials or irrigant solutions and to prevent contamination of the root canal system with nosocomial bacteria (Figure 3). The clinician may also consider the use of gingival barriers such as caulking or putty material to ensure the sealing of the rubber dam.¹⁴ The patient's oropharyngeal reflexes under IV sedation are reduced to a level that makes the patient unaware of the treatment stage or even if the irrigant solution has leaked into their mouth. Therefore, high-volume suction should be used, as well as low-volume suction inside the patient's mouth, to avoid saliva accumulation and prevent airway obstruction.

It is important to understand that irrigation is considered the most important step in RCT, as it reduces the friction between the file and the root canal dentine, dissolves tissues and, most importantly, has an antimicrobial effect.¹⁵ Therefore, the same irrigant solution(s) are used for treatment under IV sedation. For example, sodium hypochlorite is the gold standard irrigant solution as it has antimicrobial action, the ability to dissolve the pulpal remnants and organic component of dentine and the ability to neutralize the necrotic tissues.¹⁵ A rubber dam is mandatory when using the irrigant solution, therefore, if the placement of a rubber dam is not possible, the RCT should be contraindicated.¹⁶

Single-visit versus multi-visit RCT under IV sedation

Under IV sedation, the aim of RCT is to achieve a chemo-mechanically prepared root canal system. Patients with a short window under IV sedation might require RCT with multiple visits, or they may only require sedative top-ups throughout the appointment for having a single visit RCT. However, a systematic review found that there is no significant difference between single-visit and multi-visit RCT.¹⁷ In the case of multi-visit RCT, the clinician should discuss with the patient the number of visits needed and the availability of an escort for each visit.

The importance of non-pharmacological techniques in anxiolysis

Applying non-pharmacological techniques is important in anxiolysis for successful dental treatment under IV sedation with midazolam. In most cases, it is not enough to rely on IV sedation alone to reduce the patient's anxiety and several non-pharmacological techniques can be combined.² For example, giving the patients information about what will happen (procedural information), what sensations they will experience (sensory information), and how to cope with the situation (coping information) helps to change their negative thoughts and beliefs, hence reducing anxiety.¹⁸ Moreover, modifying the clinical environment can help to reduce patients' anxiety, for example, the use of positive images and relaxing music or the use of essential oils, such as lavender, in the dental waiting area.^2,19 Lastly, asking the patients to take a ‘nice, deep breath’ using a moderately loud voice with a deep tone is effective to increase patient cooperation and also enhance the patient's sense of control.^20,21

Post-operative instructions related to dental treatment under IV sedation

Verbal and written post-operative instructions should be given to patients in the presence of their escorts (Table 1). It is essential to include written detailed instructions, such as the type of pain management medication, doses, and what the patient should do. One of the consequences of dental treatment under IV sedation with midazolam is temporary anterograde amnesia; hence, the patient may not remember the advice given afterwards. Patients should only be discharged into the care of a responsible, adult escort when their blood pressure, heart rate and oxygen saturation are within the normal range, they can walk independently without assistance and after removing the cannula.

Conclusions

RCT under IV sedation with midazolam is useful for anxious and special care patients. However, clinicians should be knowledgeable and aware of all possible risks that could be experienced during dental treatment under IV sedation. This article provides brief clinical tips for novice sedationists or endodontists in delivering successful RCT under IV sedation with midazolam.