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Dental anxiety can be a major barrier for patients seeking dental care and have profound implications on dental treatment. Anxiety is defined as a vague, unpleasant feeling of apprehension with the belief that something undesirable, uncontrollable, or unpredictable is about to happen.1,2 Dental anxiety is often related to the dental environment, negative past experiences, a learned behavior in childhood, or certain dental procedures such extractions, restorations, endodontic therapy, periodontal surgery, and hygiene.3,4 A dental phobia is the strongest form of this fear.1,2 Triggers of dental anxiety can include the sounds and smells of the dental environment, with a fear of injections being one of the most common causes of dental anxiety.1
Dental anxiety is a highly prevalent complex psychological problem that exists on a spectrum. Extreme dental phobias have been found to persist in approximately 10% of the population, while low levels of dental anxiety have been reported in up to 51% of the population; moderate levels have been measured at 36%, and severe dental anxiety at 12%.1,5,6 Various research has determined that there is a significant need and demand for sedation by dental patients, with a discrepancy between those that prefer sedation and those who receive treatment, leaving many patients underserved and undertreated.3,7,8
Management of dental anxiety may include nonpharmacological and pharmacological methods depending on the severity of the anxiety, patient medical history, access to and cost of the management method, and patient preference.2 When nonpharmacological techniques are ineffective, pharmacological measures may be deployed. The aim of this article is to demonstrate the impact of dental anxiety and describe pharmacological options available for general dentists when managing different degrees of dentally anxious patients.
Assessment, Diagnosis, and Clinical Presentations of Dental Anxiety
Dentists need to accurately assess for dental anxiety and be cognizant of the treatment options available. The degree of dental anxiety can often be measured during the initial dentist-patient interaction through verbal interviews, patient admittance, office questionnaires using various dental anxiety scales, and physical and behavioral assessments.4 Multiple scales, inventories, and questionnaires have been developed to quantify and better understand the dental anxiety experienced by patients.2,4 Early detection of dental anxiety can then allow the dentist to employ techniques that improve the patient experience.2
The clinical presentations of dental anxiety vary greatly among patients and can present as physiological and behavioral signsand are summarized in Table 1.2,4,9 These presentations may vary depending on the race, gender, age, and degree of anxiety of the patient.
Clinical Significance of Managing Dental Anxiety
Dental anxiety can greatly affect a patient's life and may be a primary factor in determining whether a patient seeks dental care and the overall success of their dental treatment.9 Dental anxiety often leads to the avoidance of dental care through missed and cancelled appointments.1,4 One study determined that approximately 50% of patients with high dental fear avoided a dental appointment for this reason, and that their dental fear decreased if sedation or general anesthesia were available to assist with treatment.3 Patients with high dental anxiety typically only present to the dental office in extreme situations, often perpetuating and reinforcing their fear with more painful and extensive treatment.2,10 Dental anxiety has a predictable impact on oral health as seen through increased numbers of missing teeth, carious teeth, and advanced periodontal disease.2 It also has a behavioral impact on patients resulting in difficulty eating, avoidance of oral hygiene, self-medication, and reduced sleep quality.2 Dental anxiety may also impact the social and psychological wellbeing of patients through low self-esteem and may affect their performance in social interactions due to pain or embarrassment.1,2
Dental anxiety not only adversely impacts the patient but can also negatively affect the dentist and lead to an uncomfortable experience for both the clinician and patient. When patients are anxious, they are less compliant with treatment and more likely to miss appointments, thereby disrupting the flow of care by the dentist.2 Appointments also require more time and resources.2 Dental anxiety can be a distraction for the dentist and may risk improper diagnosis and treatment for the patient.11 Patients with dental anxiety have been shown to have increased perception to pain and pain catastrophizing, complicating treatment and increasing avoidance by the patient.12,13 By managing dental anxiety, the practitioner can be relieved from additional stress and complete treatment more efficiently.10 By actively engaging with patients to overcome dental anxiety, practitioners can then improve the patient experience, diagnosis and treatment, oral health of the patient, and overall efficiency of the dental office.2,10
Pharmacological Management of Dental Anxiety
Correct identification of the source and level of dental anxiety can aid the dentist in deciding on the appropriate treatment options.2 Before administering pharmacological sedation, all available cognitive and behavioral interventions should be exhausted as they are safer and more cost-effective.2 These psychotherapeutic interventions can range from the dentist exhibiting good communication skills and rapport, to certain relaxation and distraction techniques, exposure therapy, and out-of-office therapies including cognitive-behavioral therapy.2
Pharmacological management should only be considered when all other nonpharmacological techniques are ineffective.2 Sedation may also be considered for traumatic or long dental procedures.14 Sedation should always have an indication and should not be used as a routine measure for all patients.2
Sedation and Monitoring
The pharmacological management of dental anxiety consists of conscious sedation and general anesthesia. Sedation is defined as the use of one or multiple drugs to depress the central nervous system (CNS) to reduce patient awareness and induce relaxation or sleep.2 It exists on a continuum ranging from a drowsy but conscious state of relaxation, to complete unconsciousness, or general anesthesia.14 In conscious sedation, a patient must retain the ability to maintain a patent airway for respiration and cardiovascular function without assistance.9,10,15 The dentist must be able to continuously communicate and interact with the patient who is responsive to physical and verbal stimuli.2,9 Challenges related to conscious sedation include access to the oral operative field, dental anxiety interfering with the sedative process, complex medical conditions, risk of loss of consciousness, and risk of respiratory and cardiovascular depression and vasovagal syncope.15
Conscious sedation methods in the general dentist office include the use of nitrous oxide with oxygen, oral administration of a single sedative drug, oral administration of a single sedative drug with or without nitrous oxide and oxygen, and parenteral administration of sedative drugs through intravenous (IV), intramuscular, subcutaneous, submucosal, or intranasal administration.14 General dentists can provide local anesthesia with minimal or moderate levels of conscious sedation upon successful completion of advanced training, while deeper levels of sedation and general anesthesia are restricted to dental specialists and medical anesthesiologists.16,17 The drugs used for conscious sedation should have a wide margin of safety to minimize risk of oversedation.2,15
Prior to sedation, patients must be evaluated for fasting, with a requirement of 2 hours for clear fluids and 8 hours for solid foods.14 During sedation, patients must continually be monitored for their level of consciousness, oxygenation, ventilation, and circulation by pulse oximetry, blood pressure, pulse, and respiratory monitoring.14,18 For safety, dentists should have accessible airway equipment, reversal drugs, well-trained staff, venous access if possible, and adequate knowledge for managing medical emergencies.15 Patients cannot be left unattended until they are suitable for discharge.14 Following sedation, patients must be conscious and oriented, vital signs stable, and ambulatory prior to discharge.14 A sedation record is required and should include the preoperative assessment, confirmation of accompaniment for discharge, vitals, medications and dose administered, time of administration and discharge, and the patient's tolerance to the procedure.14 With the exception of nitrous oxide and oxygen, patients must leave with an adult following sedation, cannot operate a motor vehicle, and must be cautioned on the use of drugs or alcohol for the following 24 hours. If a reversal agent is administered due to oversedation, patients must meet clear discharge criteria and be continuously monitored for concern of the agent wearing off and subsequent re-sedation.14
Risk is involved in all sedation, and advanced training is required to safely employ these techniques.14 Safe sedation is dependent on provider knowledge, skill, training, experience, adequate facilities, monitoring, equipment, emergency drug availability, and medical emergency training.14 All dentists and providers must be adequately trained in the provision of these medications and be prepared to manage adverse responses as necessary.2,14 Any practitioner performing sedation must be able to rescue patients that achieve a level of sedation beyond the intended amount and have the skills necessary to stabilize the patient until emergency medical services can arrive or the patient returns to a lesser level of sedation without complications.14
Proper patient selection and assessment prior to sedation is required for adequate technique selection and safety of the treatment. It should include a complete medical history, American Society of Anesthesiologists (ASA) status determination, Mallampati score, social history, sedation history, treatment plan, and an assessment of the patient's anxiety level and preferences for sedation.17 The patient's medical health is a major factor in selecting pharmacological treatment, and adequate history taking is required to avoid adverse drug interactions and physiological complications. The patient's cognitive and emotional needs and personality can also have an impact on the decision for the type of treatment selected.2 Other determining factors include the cost and availability of sedation techniques.
The ASA physical classification system determines medical stability, with ASA I and II patients being able to undergo mild and moderate sedation in out-of-hospital dental facilities, while those who are ASA III and above should be managed in a hospital setting and by those who are more qualified to do so.10,14 Patients with severe disabilities, dental phobias, psychiatric disorders, or other significant comorbidities may be candidates for general anesthesia and should be treated in a hospital setting.14
Informed consent related to any treatment is critical and must always involve the nature of the medications, the expected anxiety and pain relief, the risks and side effects related to the medications, alternatives to pharmacological management, consequences of not receiving dental care due to unmanaged dental anxiety, and costs related to the procedures. Consent should be in writing and signed by the patient or legal guardian for children.15
Nitrous Oxide and Oxygen
Nitrous oxide is a weak anesthetic gas that when combined with oxygen and used appropriately is a reliable and safe option for sedation.2 The effects of nitrous oxide are described in Table 2 and include anxiolysis and sedation, minor analgesia, muscular relaxation, and euphoria.2,15,19 It is a colorless, tasteless, odorless gas that has minimal effects on the respiratory and cardiovascular systems.19 It is the least potent anesthetic gas used, with a minimum alveolar concentration of 104% and a low risk of complete anesthesia, although there is individual variability in response to the gas.19
Nitrous oxide and oxygen inhalation results in rapid uptake by the pulmonary alveoli and is transported through the bloodstream without biotransformation.19 The gas is relatively insoluble and is excreted rapidly by the lungs upon expiration.19 The analgesia from nitrous oxide has been linked to the release of endogenous opioids and through modulation of the descending nociceptive pathways at the spinal level by gamma-aminobutryic acid (GABA) and noradrenergic peptides.20 The anxiolysis has been linked to the activation of GABA-A receptors at benzodiazepine binding sites.20 The anesthesia from nitrous oxide is related to the inhibition of N-methyl-D-aspartate (NDMA) glutamate receptors and, therefore, results in inhibition of the nervous system.20
Upon administration, 100% oxygen is given to the patient, with increments of nitrous oxide every few minutes from 5% to 10% until the desired level of sedation is reached.18 It has been determined that approximately 70% of patients will need around 30% to 40% concentration of nitrous oxide to achieve comfortable sedation for dental treatment.2 The maximum concentration of nitrous oxide that can be delivered is 70%, with most systems having fail-safe mechanisms to prevent a delivery of oxygen below 30%.18 During treatment, the level of sedation and vital signs should be monitored and recorded every 5 minutes and the patient cannot be left unattended at any point. Following administration, 100% oxygen should be administered for 3 to 5 minutes to prevent diffusion hypoxia.19 After treatment, proper documentation should include the indications for sedation and confirm pre- and postoperative vitals, as well as the concentration and duration of administration.
The advantages of using nitrous oxide and oxygen are described in Table 3 and include the rapid onset through inhalation, as well as the rapid and complete recovery prior to discharge.19 The percent administered can be rapidly titrated according to patient response and is almost immediately reversed upon withdrawal, therefore not requiring any reversal agent.19 Nitrous oxide with oxygen can be safely administered to patients with asthma and mild chronic obstructive pulmonary disease as it is non-irritating to the bronchial tissues and can minimize stress-induced bronchial reactions.19
The contraindications and disadvantages of nitrous oxide and oxygen are described in Table 3 and Table 4. The main adverse effect is nausea and vomiting, which occurs in 0.5% to 1.2% of patients and can be minimized through fasting prior to sedation.19 Nitrous oxide is ineffective in young patients that are defiant or hysterical, and is contraindicated in patients with upper respiratory tract infections, nasopharyngeal obstruction, closed tissue spaces, bowel obstructions, recent vitreoretinal surgery, bleomycin therapy, claustrophobia, and severe chronic obstructive pulmonary disease, or for those in the first trimester of pregnancy or at risk of drug dependency.19,21,22 Nitrous oxide should also be monitored closely in patients taking drugs that depress the CNS, including antidepressants, analgesics, tranquilizers, and antipsychotics, as the effects may be compounded and can lead to increased sedation.19 Long-term use can induce neurological and hematological symptoms as a result of the depletion of cobalamin (vitamin B12) and should therefore be used with caution if cobalamin deficiency is suspected.10,19 Another disadvantage of using nitrous oxide and oxygen is that specialized equipment is required, including a breathing circuit, flowmeter assembly, regulators, pressure gauges, and cylinders.2,21
Oral sedation in general dentistry most typically consists of the oral administration of benzodiazepines prior to dental treatment for anxiolysis and other effects described in Table 2. This approach is indicated for moderate to severe dental anxiety with an overall goal of conscious sedation.
The advantages and disadvantages of using oral sedation are described in Table 3. The advantages include a lower incidence and severity of adverse reactions, a high degree of patient acceptance and compliance, simple administration, and no need for additional equipment.18 Disadvantages of using oral sedation include the unreliable rate of absorption, inability to titrate, delayed onset and prolonged duration of the medications, and the need for patient cooperation.23 General dentists typically are only authorized to provide minimal or moderate sedation by the oral administration of a single drug.14 The choice of drug and dose is patient-specific and should be selected based on the patient's weight, age, medical history, and length of treatment.9
Benzodiazepines are favored in dentistry because they are anxiolytic, sedative, and can produce anterograde amnesia.18 They also have hypnotic, anticonvulsant, and skeletal muscle relaxant effects.2,9,24 Benzodiazepines are widely used for minimal and moderate sedation as they have proven efficacy, low toxicity, and minimal contraindications.9,25 The pharmacological action of benzodiazepines involves inhibition by binding of GABA receptors in the CNS resulting in the increased frequency of opening of chloride channels and subsequent hyperpolarization and inhibition of transmission of nerve impulses.18,25 This reduced propagation results in a decreased psychosomatic response to stress.9 A major advantage of benzodiazepines is their wide margin of safety and high therapeutic index when prescribed in appropriate doses.18 It is important to note that benzodiazepines have no analgesic properties and still require profound local anesthesia prior to treatment.15
When administered orally, benzodiazepines are absorbed in the gastrointestinal tract and redistribute to the brain and CNS, are metabolized by cytochrome P450 enzymes, and are eventually excreted by urine.26 With proper dosing, minimal cardiovascular and respiratory effects are observed in healthy patients, whereas respiratory depression and upper airway obstruction may be seen at increased dosages.9,24 Adverse effects of benzodiazepines vary depending on the drug and dose administered and are outlined in Table 4.9,20,21 A contraindication for using benzodiazepines include patients with renal problems as these drugs are eliminated by the kidneys.9 Also, obese patients need to be carefully monitored as benzodiazepines are highly lipophilic resulting in a delayed release and a "hangover" effect.9 Chronic use of benzodiazepines during pregnancy has been shown to cause fetal dependence and withdrawal and are not recommended in general dentistry.22 Other contraindications are listed in Table 4 and include glaucoma, myasthenia gravis, allergy, breastfeeding, psychiatric comorbidities, and patients with mental deficiencies.9 The effects of benzodiazepines are enhanced by other drugs as listed in Table 4 and, therefore, drug interactions should be avoided or used with extreme caution.9,15
Oral Sedation of Adult Patients
The most common benzodiazepines used for the sedation of adults in dentistry include triazolam, diazepam, midazolam, and lorazepam, with others such as temazepam, oxazepam, and alprazolam available for use. All of which vary in onset, metabolism, duration, and degree of sedation.18 The effects of these drugs vary in terms of sedation, hypnotic effects, skeletal muscle relaxation, anticonvulsant effects, saliva reduction, vomit reflex, coronary dilation, and neuromuscular blocking.9 These drugs, including their associated indications, adult doses, onset, duration, half-lives, active metabolites, and pregnancy classifications are outlined in Table 5.9,10,14,18,24
Triazolam is often considered the first choice for oral sedation in adults due to its short half-life, lack of active metabolites, quick onset of action, amnesic effects, and minimal residual drowsiness or patient discomfort.10,18 Diazepam is a longer-acting drug that may be indicated for longer appointments.9,18 Temazepam is a minor metabolite of diazepam and is often used to treat insomnia.26 Oxazepam is the main metabolite of diazepam and can be used for short appointments with a relatively short half-life and no active metabolites.18 Lorazepam is another long-acting benzodiazepine with a longer onset time when compared to diazepam and may be useful for pre-medication prior to appointments.18 Alprazolam is a longer-acting benzodiazepine that is most commonly used for patients with generalized anxiety or panic-type anxiety.18
Oral Sedation in Pediatric Patients
Oral sedation can be very useful for treating dentally anxious children. The indications for use are the same as for adults, although the type and amount of drug administered varies. In pediatric patients under age 12, practitioners with advanced training may consider the administration of oral sedation; the dose is calculated based off of the weight of the patient and level of desired effect.14
The most common sedative for children is midazolam because it is shorter-acting, produces no active metabolites, and has little hangover effect.10,26 For administration, it is typically mixed with a sweet vehicle, such as syrup, and is given orally 20 minutes before the procedure.15 Midazolam in children can lead to hyperexcitability, increased anxiousness, and combative behavior.24 Hydroxyzine is an antihistamine that is also used for its sedative effect prior to dental treatment and has anti-emetic and saliva secretion-reducing properties.27,28 It is a very safe medication with relatively few side effects and has been shown to be successful in 78% of cases when used alone, and even greater success when combined with nitrous oxide.27,28
Benzodiazepine Reversal Agent
Flumazenil is a competitive agonist of the GABA-A receptor and is used as a reversal agent for benzodiazepine overdose.15,24 This drug can rapidly reverse benzodiazepine oversedation and is required in-office as an emergency medication. It reverses the CNS and respiratory depressant effects, as well as the amnesia and sedative effects of benzodiazepine.24 Flumazenil can be administered through IV, sublingual, and intramuscular routes.18 It has a short half-life, short duration, and rapid clearance, and careful monitoring is required as re-sedation can occur.18 The effect of flumazenil is rapid, with an onset in 1 to 3 minutes. It may be contraindicated in those that regularly take benzodiazepines for seizure disorder or for those taking high doses of tricyclic antidepressants.15,24 Details of flumazenil dosages are outlined in Table 5.
Combination Therapy for Sedation
Oral sedation may also be used in conjunction with nitrous oxide for patients with more severe levels of anxiety. There are many benefits of combination therapy, including titration of the effects of sedation and the additive effect of each technique.18 When oral sedation medications are administered, multiple doses or incremental dosing is strongly discouraged due to the delayed onset and increased risk of overdose.14 Combining therapies may be advantageous when the current level of oral sedation is less than desired and allows for slow titration of the nitrous oxide to reach the desired level of sedation.18 The combination of nitrous oxide and midazolam has been shown to reduce the amount of total midazolam used, allowing for a better safety profile and predictable level of sedation than when used independently.29 This technique also allows for improved acceptance of the nasal mask for delivering nitrous oxide.29
Intravenous (IV) Sedation
IV conscious sedation refers to the parenteral administration of sedative drugs into the vascular compartment with increasing use in dentistry to better manage pain and anxiety.2,24 IV sedation can be used to achieve moderate conscious sedation, but may also be used to reach deeper levels by those with specialty training. For the purposes of this article, the focus will be specifically on the use of IV sedation for achieving moderate conscious sedation by general dentists. IV sedation requires advanced training, and the dentist must have adequate knowledge for safe administration and management of medical emergencies.14,24 It requires a team of at least three people to safely monitor and assess the patient.14 For a general dentist, parenteral administration may consist of a single benzodiazepine or may be combined with any other sedative drugs, such as opioids during the peri-operative period.24
Advantages and disadvantages of IV sedation are described in Table 3. A major advantage of IV sedation is the ability to titrate the medications depending on patient response.24 Also, a more rapid onset of action and higher levels of efficacy are achieved when compared to oral and inhalation sedation.2 Another advantage is that there is readily available IV access for the administration of emergency drugs or reversal agents if needed.2 Disadvantages of IV sedation include the need for additional equipment, staff to monitor and assist with sedation, and increased risk of deeper levels of sedation due to the rapid onset of action.24
The drugs used for IV sedation most commonly are benzodiazepines such as midazolam and diazepam, and certain opioids such as fentanyl. The IV drugs that can be administered by a trained general dentist depend on the guidelines as set by the local medical and dental regulatory governing bodies. Both midazolam and diazepam are lipid-soluble drugs formulated in solutions prepared for intravenous administration.24 Midazolam is highly lipophilic and, therefore, has a fast onset in the CNS and a large volume of distribution.24 Due to its metabolism and clearance, midazolam is considered a short-acting drug when compared to diazepam.24 The reversal agent, flumazenil, is administered IV when needed in cases of oversedation. The medications and doses used for IV sedation in adults are summarized in Table 6.14,24
Effective local anesthesia is essential to reduce or eliminate the pain of the procedure, can have profound implications on the patient experience, and improves both short-term and long-term dental anxiety. It should be noted that sedation does not directly manage pain and local anesthetics are still required to appropriately manage the patient.2 Dental anxiety is highly associated with pain catastrophizing, which may influence the patient's experience of pain and lead to avoidance of dental treatment.13 The providing dentist must be aware of the maximum doses and contraindications related to local anesthetics and be well versed in the techniques used to administer them.30
Children, Elderly, Special Needs, and Medically Compromised Patients
Some patient populations require more specific guidelines and attention when performing sedation, including children, the elderly, those with special needs, and medically compromised patients.14 It is important to note that sedation of these populations requires adequate training and certification by a dental professional, who must practice within the guidelines as set by their local medical and dental regulatory governing bodies.
Nonpharmacological techniques are essential and valuable for managing dental anxiety in children. Many factors for pharmacological sedation need to be considered, including the age and weight of the child, their level of dental anxiety, their mental attitude and level of cooperation, the number of appointments necessary, their treatment needs, emergency management, their physical activity, gastric contents, distance traveled from the office, and the parental choice of sedation. Dosing for children should be based on the weight of the child, and special precautions should be taken for children who are overweight or have a high body mass index.24 Children vary greatly in terms of their physiology and airway anatomy, and the dentist should have all of the appropriately sized equipment available.18 Airway examination for pediatric patients is critical to assess for adenotonsillar hypertrophy or other abnormalities that can lead to upper airway obstruction, and the dentist must be aware of the increased risk of hypoxemia in children.24 It has been recommended that children beyond ASA I should be treated in a hospital setting for sedation.15 For patients under the age of 12, sedation should only be performed by those adequately trained and certified to do so. All children have reduced physical reserves as compared to adults, and oversedation can occur much more rapidly.14
In elderly and medically compromised patients, dentists should be careful to determine any risk of drug interactions or medical contraindications to sedation, and dosing may need to be adjusted as needed.9,14 Patients who are ASA III and above are to be treated in a hospital setting by those who are qualified and certified to do so. Patients with special needs who require sedation should be considered for care in a hospital or by a dental specialist.
This article reviewed the pharmacological management of dentally anxious patients as typically provided by general dentists. It clinically identified and categorized dental anxiety and provided basic guidelines on the use of nitrous oxide and oxygen, oral sedation, combination therapy, and basic intravenous sedation in the general dental office.
Dental anxiety can significantly impact a patient's oral and psychological health and may be the determining factor in whether a patient seeks dental care. If administering sedation, dentists must have adequate training and certification to do so and know the indications, contraindications, adverse effects, and drug interactions related to each sedative technique. Also, the dentist must be well-trained in managing a medical emergency if it were to arise in the office. Each patient must be assessed on an individual basis, and the sedative technique chosen should best suit the medical and treatment needs of the patient. Sedative techniques should not be used in a generalized manner for all patients. By addressing and managing dental anxiety, dentists can improve access to dental care for many patients and create a more comfortable experience overall for both the patients and dentist.
About the Authors
Erin Husack, DDS
General Practice Residency Private Practice, Edmonton, Alberta, Canada
Aviv Ouanounou, BSc, MSc, DDS
Associate Professor, Department of Clinical Sciences (Pharmacology and Preventive Dentistry), Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada; Fellow, International College of Dentists; Fellow, American College of Dentists; Fellow, International Congress of Oral Implantologists
Queries to the author regarding this course may be submitted to email@example.com.
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