Children's uncooperativeness in dentistry has been conceptualized in different ways. Dental fear (DF) and dental anxiety (DA) are used to denote early signs of dental phobia (DP): an excessive or unreasonable fear or anxiety with regard to the challenge/threat of dental examination and treatment, which influences daily living and results in prolonged avoidance of dental treatment [1]. Dental anxiety and fear (DFA) in children has been recognized in many countries as a public health dilemma [2], and has been studied at length. In the late 1960s, Norman Corah developed the Dental Anxiety Scale (DAS), providing an organizing principle to examine this issue [3]. Dental fear is a normal emotional reaction to one or more specific threatening stimuli within the dental situation, while DA denotes a state of apprehension that something dreadful will happen in relation to dental treatment, coupled with a sense of losing control. Dental phobia represents a severe type of DA and is characterized by marked and persistent anxiety in relation either to clearly discernible situations/objects (e.g., drilling, injections) or to dental situations in general [4]. Henry Lautch investigated whether these patients'fear was related to the nature and the characteristics of dental care [5], while Elliot Gale concluded that clinicians needed to assess the situation of the patient, rather than actual pain under any circumstances, when assessing DF [6]. Moore et al compared the overall demographic trends and their relation to the factors and degrees of DF [7].

Among other physical problems seen after birth and persisting into adolescence, toothache due to dental caries often begins in infant. Despite great progress in dental health through dentistry, most youths require dental treatment of various forms. However, teenagers, who are often immature psychologically and physically, can manifest a great fear of dental treatment. Holtzman et al found that, patients for fear of dental treatment missed appointments 3 times more than other patients. They did find that as age increased, fear and anxiety decreased, measured through physiological responses to critical reaction symptoms, such as patients'muscle tension when sitting in the dental chair; further, that younger women expressed more DF than older women, while men reporting DF was unrelated to age [8]. Similarly, many investigators have reported fear of dental treatment in children that may result in treatment management difficulties [9]. Behavior management problems are also related to dental factors, such as earlier negative treatment experiences [1011], particularly injection, drilling, and extraction, which have been shown to carry the most negative emotional loads [1213]. Furthermore, the dentist's attitude toward the pediatric patient is of vital importance for good treatment outcomes [14]. A study of children aged 5 to 11 years by Milgrom et al. [15] suggested that conditioning is an important contributor to DF in childhood and adolescence. Prevalence estimates of childhood DF vary considerably, from 3% to 43% in different populations [4]. However, there are few previous studies examining the relationship of DFA to dental pain among children and adolescents. Thus, the purpose of this study was to examine the literature regarding the prevalence of DFA associated with dental pain.

A broad search of the PubMed database was performed using 3 combinations of the following search terms: dental fear, anxiety, and dental pain and prevalence. The search was limited to publications in English that included children and adolescents aged 0 to 18 years. The cut-off date was the end of May 2015. The keywords used and the search results are shown in Table 1. Relevant publications were identified after reviewing the abstracts. Table 2 shows the eligibility and ineligibility criteria for this study.

The literature selection process was performed as seen in Fig. 1. Combining the search terms dental fear, anxiety, and dental pain and prevalence, the number of screened articles was 2,281. Much work has been published on the prevalence of dental pain, but relatively little on the prevalence of DFA. Two separate researchers selected articles. However, a large proportion of the identified articles could not be used for the review due to inadequate end points and measures or poor study design. Finally, 32 relevant articles with acceptable end points were identified and retrieved (Table 3). After that, critical assessment was performed on each article, examining the prevalence of DFA and dental pain, with differences based on age and sex.

The included articles were published between 1982 and 2015; the number of individuals surveyed for DFA varied from 52 to 4505. The prevalenceof DFA was estimated at 10%, with a decrease in prevalence with age. Dental fear and DA was more frequently seen in girls, and was related to dental pain.

Fear or anxiety about dental treatment is very common. One study suggests that, in the US, more than 80% of the population fears dental treatment, and 20% avoids the dentist due to severe DF [16]. Avoiding dental treatment due to anxiety and fear exacerbates problems related to patients' oral health. Further, treating anxious patients tends to be both more difficult and more time-consuming. Because dental patients feel anxiety and fear associated with dental treatment, it has been vital for dentists to construct an environment that alleviates patient worries. Effective regulation of anxiety and pain is an essential element of dental care, allowing many patients, who previously could not be treated, to receive dental treatment, due to the extensive and various ways available to control anxiety and pain. In attempts to solve these problems, studies examining causes of DFA, as well as its prevalence, patient categories, and its impact on intra-oral and extra-oral environments and treatment plans have been conducted. However, the use of such methods in clinical situations is low due to lack of understanding, time constraints, and translation difficulties.

Dental anxiety and DF among both adults and children has been recognized as a problem area in clinical dentistry for many years, but only a small number of investigations have tried to depict the epidemiologic public health factors related to DF in countries and cultures other than Western Europe and North America. Approximately 10% to 20% of the adult population in the western industrialized world report high DA; most also report this reaction as having developed in childhood [171819202122232425]. Although negative dental experiences are often cited as the major factor in the development of DA, very few studies have provided prevalence data. Prevalence estimates of childhood DF vary considerably, from 3% to 43% in different populations [2152627282930]. These differences in prevalence estimates may be due to several parameters, such as methodological or cultural variables, in the populations surveyed. For example, instruments used in these studies vary from behavioral rating scales to several forms of fear questionnaires, such as the DAS [3] and the Dental Subscale of the Children's Fear Survey Schedule [31]. Corah's DAS, published in 1969, consists of 4 questions with 5 answer alternatives for each [6] the scores may range from 4 (no anxiety) to 20 (high anxiety) [3]. The Dental Fear Survey (DFS), originally a 27-item self-assessment survey published by Kleinknecht et al. in 1973, was later revised to a 20-item version [32]. Two items focus on avoidance, 5 on self-perceived signs of physiological arousal, 12 on fear of specific dental situations and procedures, and 1 (item 20) on DF in general. Each question has 5 unimodal answer alternatives using an ordinal level of measurement. The summed scores may range from 20 (no fear) to 100 (terrified), but the DFS is primarily designed to detect the fear induced by the separate items.

In 1990, Weiner and Smehhan published the Fear Questionnaire (FQ), consisting of 2 parts [33]. Part A contains 16 five-point questions. Approximately one half of the list was similar to the Anticipated Anxiety Level Chart [343536], with which commonly occurring general and dental fears were studied. Part B examines autonomic stress reactions in particular, with 18 five-point questions, of which 3questions deal with severe anxiety attacks. The answer alternatives are unimodal and are of the ordinal level of measurement. The 2 parts of the FQ contain 4 orthogonal, reliable factors. Four factor indices are computed, for "generalized (endogenous) fear," "dental specific fear," "endogenous anxiety symptoms," and "exogenous anxiety symptoms." The 4 scales show intercorrelation ranging from 0.21 to 0.52, and were therefore considered to be only modestly related [33]. In 1991, Gauthier et al. published the Adolescents' Fear of Dental Treatment Cognitive Inventory (AFDTCI), developed by Morin in 1987. The AFDTCI evaluates thoughts and ideas that an adolescent may experience during dental treatment. The questionnaire originally consisted of 42 questions with ordinal 1- to 5-point scales, but after assessment by 8 experts, it was reduced to 29 items. A test using adolescent subjects (n = 343) led to the removal of 6 more items, leaving 23 items in all. The scores on the AFDTCI may range from 23 (no fear) to 115 (high fear) [37].

Fear of pain was found to be the most important predictor of DA; issues of control were also related to DA. Therefore, it was predicted that gender and age differences would be reflected in attitudes toward pain and control. Childhood fears are often related to developmental changes in children, and the nature of fears prominent in a child's life also seems to depend on the child's age [3839]. For a preschool-aged child, attachment and separation anxiety often play an important role, whereas at a later age (≥ 8 years), fear of bodily injury and social ostracization become more prominent. Most of these developmental age-appropriate fears decrease or disappear as children grow older, due to increased ego strength and cognitive ability development, thus providing children with adequate coping styles. Accordingly, from a developmental perspective, young children are expected to suffer some degree of fear when visiting the dentist for the first time, possibly due to being separated from a parent, not understanding the dental procedures, or associating these with other, age-appropriate fears. In most children, this fear will probably decrease after visiting the dentist more often and thereby becoming habituated to the dental situation. However, in a small subgroup of children, fear seems to persist into adulthood and become chronic. It has been suggested that patients need to have the attitude and desire to actively use these evaluation methods, rather than paying constant attention to the anxiety regarding dental care.

Dental fear, DA, and dental pain are common, and several psychological factors are associated with the development of these problems. The prevalence of DFA is estimated to affect 10% of the population, with a decrease in prevalence with age. We also found that DFA was more frequently seen in girls, and that it was related to dental pain. In order to better understand these relationships, further clinical evaluations and studies are required. Further research, using more appropriate methods, is needed to clarify the role of dental pain in the genesis of DFA.