Dental Anxiety: Etiology and Treatment Options

Summary Dental anxiety might be the cause of serious health problems. Avoiding dental visits can lead to complications with functional, esthetic and sociological consequences. In order to have a simple and efficient dental procedure, it is very important to diagnose dental anxiety and to react adequately. The aim of this paper is using available literature to present most frequent causes, consequences as well as treatment options for dental anxiety. Treating dental anxiety and choosing the right treatment is not always easy, however, it is important for dental practitioners to be able to assess patient’s behavior, possible causes of such behavior and select adequate therapy methods. Individual approach is very important as well as timely recognition and gradation of dental anxiety in order to apply adequate and successful dental treatment.


INTRODUCTION
Dental fear is a significant social problem and it is present both in children and adults. Despite technological development and modern approach to prevention and therapy of oral diseases, dental fear is still one of main reasons why people neglect oral health. Fear of dental treatment could be the cause of serious health problems since avoiding dental visits undoubtedly leads to complications regarding the treatment of impaired oral tissue [1]. Relationship between the patient and dental practitioner where patient`s anxiety dominates, might trigger serious issues (for both the patient and the practitioner) that could lead to misdiagnosis and inappropriate dental treatment [2].
The term "fear of dentist" includes dental anxiety, dental fear and dental phobia [3]. Dental anxiety is the most benign type of fear of dentist. It is the state of apprehension that something unpleasant is going to happen in relation to dental treatment and it is coupled with a sense of losing control [3,4]. It usually precedes facing an object or situation that causes fear. Dental fear is an active reaction to a familiar danger, i.e. object or situation, since it appears among the persons who already had adverse experience with dental treatment and who anticipate the same scenario [5]. Worry and fear could easily trigger dysfunction of psychological, cognitive and emotional components of behavior in these persons [6]. Dental phobia is the most intensive form of fear of dentist. In comparison with excitement and fear, phobia is a clearly defined diagnosis by appropriately skilled psychologists and psychiatrist. It is a mental disorder with very pronounced fear or avoidance of a certain object or situation that significantly obstructs patient's functioning or causes major emotional stress [5,6].
Relationship between fear and pain is also very important for dental practitioners. Physiological processes usu-ally trigger pain. In addition, it might also have a strong cognitive component so that patients with dental anxiety have exaggerated expectations of pain, i.e. exaggerated pain sensation in general [7,8,9]. Therefore, dental practitioners should be aware of pain complexity usually coupled with dental fear.
Due to extreme fear of dental treatment, psychological reactions are very common in dental office. The most common reactions are palpitations, rapid heartbeat, high blood pressure, sweating, feeling of discomfort or stomach sickness, shortness of breath, anxiety and trembling. Psychological reactions usually precede syncope although they can often appear independently, prior dental treatment.
The aim of this paper is using available literature to present the most frequent causes, consequences and treatment options for "dental fear".

PREVALENCE OF DENTAL ANXIETY
Regardless of advances in technology and methods of dental treatment, the prevalence of dental anxiety has not decreased significantly [1,5,6,10]. The prevalence of patients with high anxiety level varies, but it is believed that dental anxiety in North America population ranges from 10% to 20%. Other studies show that prevalence of dental anxiety in different population ranges from 4% to 30% [1,5,[10][11][12][13]. Avoiding dental treatment due to dental fear is present in 6-15% of adult world population [11]. Haiser et al. [11] state that 4-20% of adult patients express high dental anxiety while 2-3% of adults express avoidance of dental treatment similar to phobia. Enkling et al. [14] presented the prevalence of dental treatment fear of 11% in Germany, while Norwegian study showed 10% [5]. Furthermore, every third woman in subpopula-tion between 30 and 45 year of age shows high degree of dental fear [12,13,15]. Hmud and Walsh [16] stated that fear reduces with age while other studies have not established the correlation between age and fear. Correlation between socioeconomic status, education and fear has also not been clearly defined [16].

CAUSES OF DENTAL ANXIETY
Many studies support the thesis that pain or fear of pain is the primary cause of dental anxiety. This is confirmed by the fact that patients with high degree of anxiety are much more sensitive to pain [17,18]. Bare and Dundes [19] described numerous causes of dental fear: previous painful experiences, stories heard from other people, fear of pain, fear of needle and anesthesia, fear of sounds produced by dental drills, fear of criticism regarding teeth condition, fear of blood, fear of choking and gagging, feeling of vulnerability, loss of control i.e. impossibility to prevent uncomfortable situation, fear of unknown, some people even feel discomfort caused by distinctive odors in dental office. Even the act of intraoral local anesthesia application is for many anxious patients the most stressful and frightful moment whereas the sound of drill is the major cause of fear [20].
Many psychological conditions include dental anxiety (obsessive-compulsive disorder, fear of microbes, agoraphobia and depression) [21][22][23][24][25][26][27]. Increased dental anxiety is characteristical for patients who were the victims of abuse in the past. Children and women who suffered abuse of any kind usually subconsciously keep in their memory feelings related to that horrifying event. Dental treatment might trigger interaction between momentary and repressed event, therefore these patients avoid dental treatment because of negative associations and feeling of losing control. Persons suffering from posttraumatic stress disorder (PTSD) regardless of its cause may show increased dental anxiety as well. These patients might easily develop phobia followed by nightmares where dental practitioner has the leading role.
Even though there is no genetic basis for fear of dentist, it is proved that mutation of gene MC1R decreases the efficiency of anesthetic solution in dentistry. Persons with mutation of gene MC1R, usually characteristic for people with naturally red hair, need 20% larger dose of anesthetics than usual. Therefore, persons with such genetic variations show greater fear of dental treatment [28]. Fear of dental treatment is ranked 4 th among other situations that cause fear [29]. Aartman [30] studied various types of dental treatments and reported that tooth extraction causes the greatest level of anxiety among the patients. Tooth extraction is followed by the treatments that include use of handpieces and rotary instruments.
Corah's Dental Anxiety Scale is used to assess patient's level of fear (DAS-R, dental anxiety scale). It consists of four questions, each question containing 5 answers. Answers are scored according to 5-point Likert Scale (a=1, b=2, c=3, d=4, e=5), where the degree of anxiety is calculated according to the sum of scores: 0-9 not at all, 9-12 somewhat, 13-14 very much, 15-20 extremely [31]. Nowadays, the most acceptable scale is modified MDAS scale per Wong [32], which contains 8 questions about various dental procedures (including physiological, cognitive, emotional and behavioral components of dental anxiety). It also uses 5-point scale to assess the anxiety level that ranges from relaxed to very anxious.
Physiological reactions to anxiety during dental treatment include increased blood pressure, rapid breathing, fever, whereas high heart rate is a very useful factor for assessing the level of anxiety [33,34]. Literature suggests the use of radial immunodiffusion (laboratory technique for determining immunoglobulin concentration) to demonstrate the effectiveness of anxiety treatment methods by measuring the level of antibody known as Secretory Immunoglobulin A (S-IgA) that is considered stress marker in patients with dental anxiety [33].

CONSEQUENCES OF DENTAL ANXIETY
Literature has shown significant correlation between anxiety and poor oral health, poor oral hygiene and esthetics. That inevitably generates poor quality of life in general, coupled with major emotional, psychological and social problems. Dental anxiety is associated with increased level of caries and behavioral management problems in children [19,35]. The study from 2003 conducted by Norwegian researchers shows that persons with high level of dental anxiety have statistically poorer oral health in terms of decayed and missing teeth, as well as oral dysfunction compared to the patients who do not suffer from dental anxiety [5]. Feared patients find dental visits extremely stressful and decide to avoid them. Often, they turn to "natural remedies" [1]. Such behavior usually leads to irregular dental visits with only emergency dental treatment or even sometimes total avoidance which leads to deterioration of oral and general health as well as associated feelings of anxiety, shame and inferiority.

DENTAL ANXIETY TREATMENT OPTIONS
Due to widespread dental anxiety, clinicians should be trained to recognize predisposition, etiology and dental anxiety treatment options [36]. If dental fear and anxiety are not diagnosed and properly treated, feared patients enter the vicious circle, as avoiding dental visits significantly worsens their problems [20,30]. Even though dental anxiety questionnaire is highly recommended, its use in everyday practice is limited [36,37]. In order to respond adequately, it is necessary to properly diagnose dental anxiety [37,38], since that significantly increases the probability for successful treatment of feared patients [39].
Dental anxiety is the mildest form of fear of dentist that can be easily solved if trusting practitioner-patient relationship is established i.e. if patient is provided realistic information about dental treatment [40]. An additional problem represents the fact that in the age of information, patients usually refer first to magazines and internet that could cause additional, adverse consequences due to wrong and malevolent information. Through conversation, the patient should be encouraged and explained the necessity of dental procedure. That is usually enough to increase patient's pain threshold that is the main cause of dental anxiety. Greater dental anxiety may require more complex forms of therapy [40]. If conversation is not sufficient to achieve the result, it is necessary to postpone the treatment or apply pharmacological support (nitrogen oxide or oral sedation) or to use various techniques such as distraction, relaxation or other methods. High level of dental anxiety may necessitate some form of cognitivebehavioral interventions (best by referral to psychologists and psychiatrists), such as systemic desensitization, cognitive restructuring or hypnosis [5]. If there is an indication for urgent dental treatment and there is no time for adequate preparation of patient with high dental anxiety level, interventions could be performed with application of intravenous sedation, conscious sedation or even general anesthesia [41,42]. In some cases, especially if patient's oral status is considerably deteriorated, the first dental treatment under sedation may be indicated [43].
Gaining trust in dental team is according to Bernson et al.
[44] very important to successfully neutralize dental anxiety. According to their study, two out of four anxious patients confirmed that trustfull interaction with the dentist and possibility to control the situation helped them complete dental treatment. Good communication between dental practitioner and patient is crucial for productive working relationship that results in adequate clinical care. Studies conducted by Corah et al. [45] and Hamasaki et al. [46] showed that efficient mutual interaction, understanding of patient's concerns, active listening with empathy and adequate, pleasant voice decrease patient's anxiety [47]. Information obtained from practitioner could be two-dimensional i.e. information obtained prior to the treatment explaining the treatment, length of treatment, recovery or information provided by practitioner during the treatment [48]. That information is sensory information explaining patients what they can expect to feel (pressure, vibration), what part of procedure will happen, administration of anesthetics, beginning of cavity preparation. Technique ''Tell-Show-Do'' has the greatest application in pediatric dentistry, though it is often applied when dealing with anxious patients since it encourages the sense of control and predictability of the treatment [48][49][50][51][52]. During dental treatment, it is necessary to make frequent and longer breaks that would relieve the pressure on patient and enable good quality of care. Patient and practitioner could agree on signaling system used by patient if it is necessary to stop the treatment or if patient feels pain. This builds trusting relationship. "Positive reinforcement" of patients with small, tangible rewards or verbal acknowledgement may provide encouragement for cooperation and appropriate behavior, even though it is not scientifically proved [5]. Verbal reinforcement with short breaks (5-15 seconds) during the treatment often results in calm and cooperative patient [53]. If dental treatment implies painful reaction, an anesthetic solution should be administered to patient, (provided that there are no contraindications), since psychological reactions are often triggered by fear of pain [53].
It has been confirmed that focusing attention on visual and auditory stimuli in dental office or waiting room might be beneficial for patients with mild to moderate dental anxiety. Modern dental office is equipped with video or DVD or even special 3D video glasses for watching movies, video clips or even playing video games during dental treatment. Prabhakar et al. [54], have found that such distractions reduce dental anxiety, while patients who experienced such treatment insisted on having the same treatment during following visits. This program is very popular among younger patients with mild to moderate level of dental anxiety [55]. Music might be an alternate treatment option as it has been used in different medical fields to meet physiological, psychological and spiritual needs of patients. Anxyolitic effect of music has been studied in the last 20 years in a variety of medical patients, mostly surgical, cardiac and oncology patients [1]. It may be used as active musicotherapy or passive listening of soothing, relaxing music in the waiting room or during dental procedure [55,56,57].
One of ways to treat dental anxiety in patients could be detailed description of dental procedure, pharmacological strategies including benzodiazepines and antidepressants, application of bioenergy, hypnosis and behavioral therapy [3]. Behavioral therapy is sometimes more benefitial than anxyolitic application, since patients usually prefer nonpharmacological therapy [52,58]. Most of behavioral treatments include components based on systematic desensitization and use of relaxation to neutralize and reduce fear during gradual exposure to the treatment [59]. Bergen and Kol have presented a study where they described cognitive therapy vs. muscular relaxation to reduce fear [60].
Application of acupuncture prior to dental visit could be an efficient method for reducing anxiety and fear [61]. Acupuncture is traditional Chinese technique (gained acceptance by WHO in 1975) that differentiates 12 main meridians and 361 acupuncture points on human body. Point KI3 located on the inner side of the foot, halfway between the Achilles tendon and the side of the anklebone, is used to reduce pain. For mild anxiety level it is sufficient to perform the treatment prior to dental visit, while in case of severe anxiety and fear, it is necessary to make an assessment and individual treatment plan which consists of 3-10 treatments [61].
There is a study supporting breathing exercise for reducing patient`s anxiety [39]. Physiological changes following relaxation and diaphragmatic breathing are widely used in stressful situations and they are especially efficient in reduction of experienced pain [62]. This is, perhaps, not surprising since dental literature confirms the association between greater anxiety and increased pain perception [63][64][65][66]. Fear is under control of sympathetic nervous system that decreases pain threshold [67]. There are controlled breathing techniques; Milgrom et al. [39] described one where patient takes slow but deep breaths holding each breath for approximately 5 seconds before slowly exhaling. Slow and steady breathing for 2-4 minutes reduces patient`s heart rate and makes anxious patients noticeably more comfortable [5]. Progressive muscle relaxation is proved to reduce dental fear and anxiety, in general [68]. It is basic principle of physiology that explaines when a muscle is tensed, releasing tension causes muscle relaxation (breathing becomes slower and deeper, heart rate and blood pressure decline, vasodilatation in small capillaries of extremities might become noticeable, patient has the sense of calmness and ease) [69]. This procedure is relatively simple, but it requires that patients practice at home (once or twice per day for two weeks) [39].
Cognitive restructuring aims to alter and restructure negative cognitions and enhance individual's control over such thoughts. This process includes identification of wrong and negative thoughts and interpretations often associated with dental fear, challenging patient's evidence for them, and then replacing them with more realistic thoughts [68,70]. Clinical psychologists use this specific method but dental practitioners can use this technique as well. Systemic desensitization is a method of gradual exposure to fear and involves slowly exposing a patient to the situations that have negative connotation and to which the patient reacts with the sense of fear and discomfort. This method is effective in post-traumatic stress disorder. The patient is exposed to certain situations with intensity defined by patient's therapist, in controlled environment in order to learn how to most effectively control patient's thoughts in given situations. This method implies gradual stress exposure while encouraging patient to use relaxation techniques to reduce fear (e.g. if patient is fearful of needle, dental practitioner gradually and slowly expose patient to the idea of dental anesthesia). Hakeberg et al. [71] conducted a ten-year study that showed systemic desensitization superior to pharmacological treatment with diazepam. The application of this method usually includes the use of computer and video presentations that will gradually expose patients to different procedures. Hypnosis may be applied as a method for reduction of dental anxiety but only with patient`s request and consent. During hypnosis, the therapist enters certain parts of consciousness while focusing on dental anxiety, also change patient's unpleasant experience and make following dental visits easy [20]. In some cases, Freud's phobia therapy is very efficient.
If dental practitioner thinks that the treatment is not possible without sedation, pharmacological method is usually applied. Premedication is commonly performed with sedatives and anxiolytics. Benzodiazepines are preferred since they cause CNS depression. In that case, it is possible to perform dental treatment and keep verbal communication with the patient. Diazepam 5−10 mg is a drug of choice. Diazepam is used 1−2 hours prior to the intervention and it causes mild pre-operative calming of patient and reduction of anxiety immediately prior to intervention [72]. Sedation may be applied orally, nasally, sublingually, intramuscularly, rectally or by inhalation. It is recommended that premedication is performed one hour prior to intervention, in dental office. Inhalation sedation includes the use of inhalation device that mixes two gases -oxygen and nitrous oxide -in small concentrations (20-50%), for 10 to 15 minutes. Inhalation nasal mask is used for application. The application begins with pure O 2 , then nitrous oxide, and at the end, pure oxygen again [72]. General anesthesia is indicated in case of pathological fear of dentist (phobia), as well as in case of disabled patients [72]. Anesthesia with intubation is very common and it is usually performed by a team of dental practitioner, anesthesiologist, and sometimes, specialists in medical fields depending on patient`s diagnosis. Naturally, patients with extreme degree of dental fear should first receive psychiatric treatment in non-dental setting. Treating dental phobia, which is the most complicated dental anxiety may be long and difficult. Only psychotherapist and psychiatrist perform it while dental practitioner should recognize and refer patient.

CONCLUSION
Fear of dentist should not cause avoiding dental treatments. Not having regular follow-up examinations may multiply potential oral problems and make them even more complex. Small caries lesions tend to become worse and inevitably damage dental pulp making endodontic intervention necessary, which is more complicated and expensive. Also, gum inflammation not treated adequately and on time could lead to periodontal problems and tooth loss with functional, esthetic and sociological consequences.
Key to success in neutralizing dental fear is trustful relation established between patient and dental practitioner. Therapists should fully understand patient`s stress, have patience and time to listen the patient and recognize the cause of such condition. In addition, dental practitioners have to be skilled and educated to treat such patients. Individual approach to each patient, timely recognition and gradation of dental anxiety are necessary in order to perform adequate and successful treatment. Zavod za zaštitu zdravlja radnika MUP-a, Beograd, Srbija