Adolescence, Adulthood and Self-Perceived Halitosis: A Role of Psychological Factors

(1) Background: Halitosis is a frequent condition that affects a large part of the population. It is considered a “social stigma”, as it can determine a number of psychological and relationship consequences that affect people’s lives. The purpose of this review is to examine the role of psychological factors in the condition of self-perceived halitosis in adolescent subjects and adulthood. (2) Type of studies reviewed: We conducted, by the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analyses) guidelines, systematic research of the literature on PubMed and Scholar. The key terms used were halitosis, halitosis self-perception, psychological factors, breath odor and two terms related to socio-relational consequences (“Halitosis and Social Relationship” OR “Social Issue of Halitosis”). Initial research identified 3008 articles. As a result of the inclusion and exclusion criteria, the number of publications was reduced to 38. (3) Results: According to the literature examined, halitosis is a condition that is rarely self-perceived. In general, women have a greater ability to recognize it than men. Several factors can affect the perception of the dental condition, such as socioeconomic status, emotional state and body image. (4) Conclusion and practical implication: Self-perceived halitosis could have a significant impact on the patient’s quality of life. Among the most frequent consequences are found anxiety, reduced levels of self-esteem, misinterpretation of other people’s attitudes and embarrassment and relational discomfort that often result in social isolation.


Introduction
Halitosis, commonly called bad breath, is a problem that can affect both the external, relational, social communication and internal, psychological sphere, with implications on perceived quality of life [1]. People are usually unaware of their breath, and when they become aware of it, they incorrectly attribute the cause of their condition. Halitosis is a frequent condition, present in 50-65% of the world population [2]. Although it is a significant source of discomfort, a precise estimation of prevalence is not possible because epidemiological studies are limited. This limitation could be determined by several factors, such as the absence of a standardized method for assessment of the disease, the difficulty in recognizing its presence and the likelihood that it is in some cases transient, which is why it is underreported in epidemiological data [3]. The problem of people with halitosis is that this condition can often remain unnoticed because people are generally unaware of the quality of their oral odor. Research conducted on Korean adolescent subjects [4] has made tend to be more alert and anxious about their health, obtaining significantly higher scores in the OLT (organoleptic test, the gold standard to detect bad oral smell) and showing significant symptoms of anxiety and depression, with the anxiety itself increasing oral levels of volatile sulfur compounds (VSCs) [20][21][22][23][24][25][26][27]. A gender difference in the perception of halitosis was highlighted in one study [23]: 21.7% were male and 35.3% were female. Ashwath et al. [23] stated that self-perceived halitosis was more present in dental students. In addition, other significant relationships are found between self-perceived halitosis and other variables, including paternal and maternal education (illiteracy scores high compared to fathers and mothers with a diploma or university degree), dental brushing (the highest scores were related to an absence of brushing, compared to those who practiced oral hygiene three times a day) and the use of dental floss and mouthwash. Recent studies have suggested that socioeconomic inequality may affect halitosis awareness [28] and that halitosis reporters tend to have difficulty contacting the dentist [29]. A further factor to consider is the relationship between smoking and halitosis awareness: 2% of females and 14% of males report smoking, and this has been found to be significantly associated with self-perception. Gender differences in tobacco use have been attributed to cultural issues [30]. Recent studies confirm that self-perception of halitosis may be related to a psychogenic or psychosomatic disorder and has a strong psychological impact [31,32].

Materials and Methods
A review strategy has been conducted to summarize the available results of experimental studies. This review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [33] (Figure 1). of "halitosis paradox"; i.e., while many develop wrong perceptions about their bad breath, others are not aware [23]. People who have a bad oral odor problem tend not to be aware of their bad breath, while those who do not have a bad breath problem worry excessively about having a bad odor problem. Young and middle-aged people tend to be more alert and anxious about their health, obtaining significantly higher scores in the OLT (organoleptic test, the gold standard to detect bad oral smell) and showing significant symptoms of anxiety and depression, with the anxiety itself increasing oral levels of volatile sulfur compounds (VSCs) [20][21][22][23][24][25][26][27]. A gender difference in the perception of halitosis was highlighted in one study [23]: 21.7% were male and 35.3% were female. Ashwath et al. [23] stated that self-perceived halitosis was more present in dental students. In addition, other significant relationships are found between self-perceived halitosis and other variables, including paternal and maternal education (illiteracy scores high compared to fathers and mothers with a diploma or university degree), dental brushing (the highest scores were related to an absence of brushing, compared to those who practiced oral hygiene three times a day) and the use of dental floss and mouthwash. Recent studies have suggested that socioeconomic inequality may affect halitosis awareness [28] and that halitosis reporters tend to have difficulty contacting the dentist [29]. A further factor to consider is the relationship between smoking and halitosis awareness: 2% of females and 14% of males report smoking, and this has been found to be significantly associated with selfperception. Gender differences in tobacco use have been attributed to cultural issues [30].
Recent studies confirm that self-perception of halitosis may be related to a psychogenic or psychosomatic disorder and has a strong psychological impact [31,32].

Materials and Methods
A review strategy has been conducted to summarize the available results of experimental studies. This review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [33] (Figure 1).

Criteria for Eligibility and Research Strategy
To identify the studies, we performed a systematic literature search on the PubMed, Scholar and ScienceDirect databases. The search was limited to studies written in English. We identified the literature from January 2010 to January 2020 using four key terms related to self-perceived halitosis, namely halitosis, self-perception halitosis, psychological factors and breath odor, and two terms related to sociorelational consequences ("Halitosis and Social Relationship" OR " Social Issue of Halitosis"). The articles of 1994 and 2001 were only cited to introduce the body image theory and to link it to the perception that each individual has of his or her own smell. The electronic research strategy used is described in Table 1. Articles were selected online in relation to the title and abstracts; articles were read in full when titles and abstracts were consistent with the objective of our study. Following this procedure, we found 889 articles on the PubMed database, 1950 articles on Scholar and 169 articles on ScienceDirect; after applying the inclusion and exclusion criteria, the total number of relevant publications was reduced to 38.

Study Selection
The articles were included in the review according to the following inclusion criteria: English language, publication in peer-reviewed scientific journals and quantitative information about self-perceived halitosis and oral hygiene. Articles were excluded based on title and abstract screen; review articles, editorial comments and case reports were also excluded. The quality of included studies was appraised by separate methods for qualitative and quantitative studies; features of study design, methodology and analysis were assessed. Qualitative studies were appraised using Critical Appraisal Skills Programme tool (CASP), while the Effective Public Health Practice Project (EPHPP) tool was used for quantitative studies. The search in the PubMed, Scholar and ScienceDirect databases provided a total of 3008 articles; no further studies meeting the inclusion criteria were identified. After eliminating duplicates, further studies were excluded according to the inclusion and exclusion criteria. After screening, 38 studies were selected as appropriate for the present review.

Bias Risk among Studies
In all studies included in this review, a potential bias of the database should be considered. Only articles in English have been used, which could have compromised access to articles published in other languages.

Results
According to the literature examined, halitosis is a condition that is rarely selfperceived. In particular, 10 articles focus on the self-perception of halitosis, 10 deal with halitosis by defining it and analyzing the epidemiology, 1 study focuses on body image related to the perception of one's smell, 7 studies analyze the different psychological factors related to halitosis and 10 studies address the sociorelational problems caused by halitosis.
Quality assessment of the selected works was performed using CASP and EPHPP tools; the results of quality assessment are reported in Tables 2 and 3. Most of the qualitative studies were found to have good quality, while some of the quantitative works showed relevant methodological weaknesses such as selection bias, unsatisfactory design and presence of confounders. Despite these limitations, studies made it possible to understand the importance of this condition and the influence it exerts on the psychorelational status of affected subjects. A summary of the selected studies is reported in Table 4. Additionally, references to the selected articles were examined in order to identify further studies that could meet inclusion criteria (Table 5). Studies found that the prevalence of self-perceived halitosis was 22.8% among the participants. The majority of subjects with self-perceived halitosis experienced bad breath on awakening (83.5%). Self-perceived halitosis was more prevalent among males than females, whereas no statistically significant differences were found between age groups. A statistically significant relationship was found between self-perceived halitosis and mouth cleaning time, and a statistically significant relationship was found between self-perceived halitosis and mouth cleaning time, shisha use or cigarette smoking [16]. In this study, it was found that the more people perceived their oral odor, the more likely they were to maintain a distance. A subgroup of individuals was identified who reported maintaining a certain distance when meeting other people, despite a self-perceived "fresh" oral odor. Self-perceived halitosis leads people to keep their distance in social interactions. The ability to recognize and perceive one's oral condition can be influenced by socioeconomic variables such as age, gender and level of education [31]. There are frequent cases of oral and dental problems in patients with depression, anxiety or schizophrenia [26]. It has been possible to understand how people have difficulty recognizing the presence of halitosis and have limited knowledge about this condition [11]. It is clear that halitosis is an unpleasant symptom and can create relational difficulties with consequences for the individual's quality of life [3]. The participants in the study were healthy subjects. Participants in some studies underwent organoleptic tests to measure breathing odor and specific questionnaires were given. Some patients with halitosis were compared with healthy subjects.
This study has identified the importance of the consequences that the perception of bad breath has on the psychorelational side and, in general, on patients' quality of life.
Overall Score 9 9.5 8 9.    Halitosis is affected by gender, with males having it more than females. Males also tend to present more with self-reported complaints of halitosis than females. Age does not appear to contribute to the incidence of halitosis.
Objective of the study was to evaluate self-perceived oral malodor (OM) and to correlate this with oral hygiene practices.
372 Saudi dental students: 109 students were males and 116 were females. The mean age of the subjects was 19-25.
Saudi dental students in the College of Dentistry at the Imam Abdulrahman Bin Faisal University (IAU), in the Eastern Province of Saudi Arabia.
The questionnaire contained three parts, comprising sociodemographic factors, subject's perceptions of OM, and the social effects thereof.
The results state that there is a prevalence of malodor among dental students. In addition, regular flossing and removal of tongue coating can significantly reduce malodor.
This cross-sectional observational study was conducted to determine the prevalence of self-perceived halitosis among adults in Riyadh, Saudi Arabia, and to assess the relation of halitosis with certain sociodemographic factors, oral habits and health practices. 3000 participants, both males and females, including senior high school students, college students and employees working in governmental offices.
The college students were selected from the major universities in Riyadh. There were 15 locations for males and 15 for females (5 schools, 5 universities and 5 governmental offices for each gender).
The questionnaire was made up of 3 parts: the first part was related to certain sociodemographic factors including gender, age, educational level and employment; the second part was related to the participant's perception of any malodor (halitosis) and its history and social effects; and the third part concerned certain oral hygiene and health habits.
The prevalence of self-perceived halitosis was 22.8% among the participants. The majority of subjects with self-perceived halitosis experienced bad breath on awakening (83.5%). Self-perceived halitosis was more prevalent among males than females, whereas no statistically significant differences were found between age groups. A statistically significant relationship was found between self-perceived halitosis and mouth cleaning time, and a significant relationship was found between self-perceived halitosis and mouth cleaning time, shisha use or cigarette smoking.
The aim of this study was to evaluate self-perception of oral malodor and oral hygiene habits amongst dental students.
285 participants in the age range of 18 to 22.
Undergraduate students of Madha Dental College and Hospital Chennai.
The questionnaire used included ten questions that assessed the presence and self-perception of halitosis and treatment (self or professional) for halitosis. It also evaluated the subjects' oral hygiene habits, including the frequency of toothbrushing, the use of interdental aids and mouth rinsing.
The results of this study indicate a higher prevalence of halitosis among this population of dental students. The difference in reporting self-perception of halitosis between females and males was found to be statistically significant (p < 0.05). Significant difference was found for use of mouth wash, presence of carious teeth, bleeding gums and use of tongue cleaners between females and males.
The objective of this study was to assess the relational impact of halitosis.
Undergraduates of University of Benin, Nigeria.
Demographic characteristics, perception of value of fresh breath in social contact, rank of halitosis in first impression impairment, frequency of encounter with halitosis sufferers and their interactional difficulties and readiness to inform sufferers about the condition were assessed using self-administered validated questionnaire.
Halitosis was considered to be the second most important factor in social interaction after body odor. The majority of respondents believed that those suffering from halitosis had difficulty finding a good job or getting married or suffered from marital disharmony.  The ICH is an important tool for determining the consequences of bad breath, allowing identification of people who may require screening for social anxiety disorder (SAD).
The aim was to determine the impact of self-perceived halitosis on social interactions and the effect of using an oral rinse to manage halitosis.
For study A, 1083 subjects. For study B, 292 people.
Study A participants were members of an online survey panel assembled by the Internet survey company Panelwizard.
For study B, the potential participants were personally approached in a square in the entertainment area of the city of Haarlem in the Netherlands.
The questionnaire contained questions about oral perception.
In this study, it was found that the more people perceived their oral odor, the more likely they were to maintain a distance. A subgroup of individuals was identified who reported maintaining a certain distance when meeting other people, despite a self-perceived "fresh" oral odor.
This study aimed to understand the psychological and social effects of halitosis among young adults and to correlate their psychosocial effects with different levels of halitosis.

patients (male and female).
Young adults between the ages of 18 and 25 visiting a private dental college in Maharashtra who perceived themselves as sufferers of halitosis.
The questionnaire included demographics and questions related to the psychological and social impact of oral malodor on their daily lives.
The younger age group showed a higher incidence of halitosis than the older age group. Both genders did not show much difference with respect to the psychological impact of halitosis; however, the social effects of halitosis were present more in women. The goal of this article was to discuss self-perception theory and its influence on recent research; it was argued that introspection is not an autonomous research method for discussing the epistemological implications of this behavioral attitude on psychology.
This study discussed introspection as an autonomous research method and independent source of data for psychology.
Eli, I., et al. (2001) The aim of the study was to discuss problems involving self-perception of breath odor in patients who complain of halitosis.
The authors suggest that every patient has a breath-smelling self-image and this varies from minimal or no distortion to severe psychopathology Faria, S.F.S., et al.
The aim of the study was to evaluate the prevalence of self-reported halitosis and its predictors and to determine the accuracy of estimates of the self-reported measures with the clinical assessment of halitosis. 5420 individuals.
Teaching staff, administrative personnel and ongoing students from Federal University of Minas Gerais.
Questionnaire containing sociodemographic, medical and dental data and self-reported halitosis measures; organoleptic test (OLT).
Self-reported halitosis was mainly associated with socioeconomic variables (age, gender, education level), oral health parameters (gingival bleeding, gingival infection, tongue coating, general oral health assessment) and impacts on daily activities (family/social environment and intimate relationships). Prevalence rates of self-reported halitosis can be considered moderate.
Goel, S., et al. (2017) The aim of this study was to assess the level of knowledge and attitude of the Indian population toward self-perceived halitosis, about its possible causes, available treatments, its influence on social relations and level of confidence.
200 subjects participated in the study.
The outpatient department of a dental hospital.
Questionnaire that investigates sociodemographic data, presence or absence of medical conditions and habits, knowledge of the causes and treatment of bad smells and oral hygiene practices.
This exploratory study shows that Indian adolescents are aware of the problem, but there is no clear knowledge necessary to have an understanding and to adopt a healthy lifestyle.
The objective of the study was to analyze the causative factors, diagnostic methods and treatment options aimed at maintaining oral health as well as restoring an individual's mental health, self-confidence and social status.
Early diagnosis of halitosis is crucial, and only the identification of the causal factors makes possible an adequate and customized treatment. Bad oral odor can often be influenced by general somatic diseases and the intake of various medications. Thus, treatment should be aimed at maintaining proper oral hygiene.
This article succinctly focused on the development of a systematic flow of events to arrive at the best management of the halitosis from the primary care practitioner's point of view.
Halitosis is an extremely unpleasant feature of sociocultural interactions and can have long-term negative side effects on psychosocial relationships. An interdisciplinary approach to the treatment of halitosis should be used in order to prevent misdiagnosis or unnecessary treatment.
This study was conducted to estimate the prevalence and associated factors of subjective halitosis in adolescents.
359,263 participants (184,801 males and 174,462 females) ranging in age from 12 to 18.
Young people from Korea.
A test was used to collect information relating to gender; age; residence; subjective health; stress level; economic level; alcohol consumption; smoking; and frequency of intake of fruit, fizzy drinks, fast food, instant pasta, sweet foods and vegetables.
In this study, factors highlighted as related to halitosis were poor health status, overweight or obesity, stress and lower economic levels. The prevalence of subjective halitosis in the adolescents studied was 23.6%. Specific psychosocial factors and dietary intake were related to halitosis.

Kisely, S. (2016)
This article discusses the two-way association between oral and mental health. On the one hand, the prospect of dental treatment can lead to anxiety and phobia. On the other, many psychiatric disorders, such as severe mental illness, affective disorders and eating disorders, are associated with dental disease.
Dental diseases can lead to teeth loss, and people with severe mental illness have 2.7 times the likelihood of losing all their teeth compared with the general population. A self-administered questionnaire was explained and administered to the patients at their first visit to the clinic by the authors. The content of the questionnaire included personal bio-data and questions related to oral malodor. Subsequently, the patients were asked to assess the severity of their bad breath using the visual analog scale (VAS).
This study revealed that most of the adult patients had halitophobia, and most of them had no associated psychosocial problems. Furthermore, their bad breath was not influenced by gender or the duration of illness.

Kuzhalvaimozhi, P., et al. (2019)
Objective of the study was to assess self-perception, knowledge and attitude of halitosis among patients attending a dental hospital in Chennai.

patients.
Patients who visited a dental hospital in South India.
A self-structured questionnaire was implemented.
Most of the participants did not have self-perceived halitosis and most participants brushed their teeth twice a day, used mouthwash regularly and had knowledge of halitosis.

Madhushankari, G.S., et al. (2015)
This review covers the pathophysiology and various etiologies of halitosis, the knowledge of which helps improve treatment options.
The patients with halitosis initially turn to dentists for improvement of the condition. Research into volatile sulfur compounds (VSCs) and their effect on oral tissues has made the problem of halitosis a cause for real concern.
The aim was to determine to what extent dental anxiety can be explained by looking at patients' characteristics solely or by considering also latent aggressiveness that could be manifested before and during the dental treatment.
A random sample of patients undergoing dental treatment at several settings located in two regions in Southern Italy. The results of the sample estimates show the importance of aggressiveness in the development of dental anxiety; a significant influence is also exerted by the presence of depressive symptoms. Furthermore, there are no significant gender differences, and there is a nonlinear relationship with age; the most significant age group is between 27 and 42 years old. Halitophobia is a condition characterized by an excessive preoccupation with the belief of having halitosis. Cognitive behavioral therapy (CBT) was successfully used to treat a man in his 20s who presented important anxiety, avoidance and safety behaviors; isolation; and depressed mood.
A 20-year-old man.
A man presenting important anxiety, avoidance and safety behaviors; isolation; and depressed mood.

Hamilton Anxiety Rating Scale (HAM-A) and Hamilton Depression
Rating Scale (HAM-D).
This study suggests that CBT techniques, most commonly used in anxiety disorders and obsessive-compulsive disorder, can be adapted to halitophobia.
This study was designed to measure self-perception, knowledge, and awareness of halitosis among female university students in Saudi Arabia.

young women.
Students from various majors in classrooms and gathering areas of King Saud University's female campus.
The questionnaire consisted of the following: 1) a cover page with a request for cooperation and instructions; 2) demographic questions; 3) substantive questions exploring the respondents' self-perception and awareness of halitosis along with their knowledge about causes and management of oral malodor.
The survey revealed low self-perception and limited knowledge about halitosis. Self-perception of halitosis was low, while a higher percentage indicated that they noticed people with halitosis. Most participants thought that the gastrointestinal tract was the primary source of halitosis.
This document defines subjective halitosis terminology.
In this study, it was concluded that dental practitioners' mission is restricted to detecting whether the halitosis is objective or not, and does not include estimating, distinguishing, assessing or diagnosing psychiatric disorders.
Patel, J., et al. (2017) The aim was to evaluate the association of social anxiety with oral hygiene status and tongue coating among patients with subjective halitosis. 321 subjects.
Subjects aged 18 or older presenting in the outpatient department with the complaint of halitosis.
Social anxiety was assessed with the 24-item self-report version of the Liebowitz Social Anxiety Scale (LSAS-SR).
This study revealed that social anxiety, poor oral hygiene and tongue coating were associated with subjective halitosis. Comparison of oral clinical parameters between the sexes revealed that poor oral hygiene was observed among male participants. The objective of this study was to estimate the prevalence of halitosis (with subjective and objective methods), evaluate the immediate effect of chewing gum on volatile sulfur compounds (VSCs), assess the perception of halitosis by dentistry students and estimate the distribution of positive and negative frequencies, when comparing objective and subjective methods for the diagnosis of halitosis.
The sample comprised 80 individuals: 59 women and 21 men aged from 18 to 40.
Questionnaire, the simplified oral hygiene index, the Winkel index, organoleptic test and gas chromatography.
The prevalence of halitosis in the studied sample was high, considering that it comprised healthy individuals.
The study aimed to investigate the psychological impact of oral disorders on people's emotional well-being, with a particular attention to gender and age differences.
The whole sample consisted of 263 dental patients, all belonging to private dental surgeries of the center of Messina.
For the analysis, the authors considered only the valid cases: 130 of them were females (56.8%) and 99 of them were males (43.2%), for a total of 229 participants.
The Profile of Mood States (POMS) and Oral Health Impact Profile (OHIP-14).
The results of this study showed a significant relationship between the perception of the patient's oral health and the mood states experienced.
The aim of the study was to analyze, by means of a questionnaire on disgust, any gender differences regarding the feeling of disgust in its various dimensions, viewed both individually and globally.
A sample of 1587 subjects was taken from the town of Messina (676 males and 911 females). Subjects were contacted by medicine students of Messina University Hospital.
The age range of participants was between 10 and 90. The synthetic disgust index (SDI) Disgust and oral contamination showed a reduction in the SDI in the group aged 18-39 years and a maximum score in the group of subjects aged 40-64 years. Disgust and oral contamination showed a reduction in the SDI in the 18-39 age group with a general tendency to decrease with age.
The aim of the study was to investigate the relationship between psychosocial impact, levels of self-esteem and the possible connection with eating habits of adolescents under orthodontic treatment.
The adolescents in treatment from 0 to 60 months at the Clinic of Orthodontics and Dentistry of Messina, Messina, Italy.
Eating Attitudes Test, the Rosenberg Self Esteem Scale, and the Psychosocial Impact of Dental Aesthetics Questionnaire.
The data did not show a direct connection between eating disorder and dental aesthetics. Adolescents under orthodontic treatment in the first phase of orthodontic appliance use showed peculiar eating habits and were more psychologically affected by dental aesthetics.
The aim of this study was to examine behavior in a sample of Italian subjects with reference to self-reported halitosis and emotional state, specifically the presence of dental anxiety.
Subjects were recruited in the waiting room of dental clinics in Messina and Reggio Calabria.
Instruments used were as follows: self-report questionnaire to detect self-reported halitosis and other variables possibly linked to it: sociodemographic data, presence or absence of medical and dental pathologies, any allergies, oral hygiene practices, medication, smoking and alcohol consumption, the importance attributed to one's own mouth and that of others; Dental Anxiety Scale (DAS).
The rate of self-reported halitosis was 19.39%. The factors related to halitosis were anxiety about relationships with the dental patient (relational dental anxiety), alcohol consumption, gum disease, age > 30 years, female sex, poor oral hygiene, general anxiety and urinary system diseases.

Slade, P.D. (1994)
A general schematic model concerned with identifying the nature of body image is presented. This model suggests that body image may be conceived as a loose mental representation of the body that is influenced by at least 7 sets of factors.
These sets are the history of sensory input to body experience, the history of weight change/fluctuation, cultural and social norms, individual attitudes to weight and shape, cognitive and affective variables, individual psychopathology and biological variables.
This book, written by world authorities in the field, is a comprehensive, up-to-date guide to the specialty of oral medicine, which is concerned with the diagnosis, prevention and predominantly nonsurgical management of medically related disorders and conditions affecting the oral and maxillofacial region.
Halitosis is an unpleasant symptom that can become a social problem compromising quality of life. This condition may affect individuals of all ages and may be a transient episode or a long-lasting problem depending on the cause. Table 4. Cont.

Publication Aims Sample Size and Characteristics Group Characteristics Mesaurement Type Results
Torales, J., et al.
The aim of this brief review was to provide information on the management of oral and dental diseases that must be provided to patients with mental illness.
The most common oral and dental problems were analyzed in patients with depression, anxiety, schizophrenia or bipolar dementia, with particular attention to their management.
Umeizudike, K.A., et al. (2016) The aim was to determine the prevalence of self-reported halitosis among dental patients observed in a university hospital.

Patients from the Oral Diagnosis/Periodontology Clinics of the Lagos University
Teaching Hospital.
The self-administered questionnaires contained information on age, gender, education, marital status, ethnicity, religion and self-perception of halitosis.
The prevalence of self-reported halitosis was 14.8% and was significantly associated with age 40 years and over and male gender. About 50% perceived halitosis from themselves, 25% from family and friends and 20% from people around them. The majority (70%) of patients perceived halitosis from the mouth, 30% from the mouth and nose. The majority (75%) of subjects had perceived halitosis for more than 4 weeks. Ziaei, N, et al. (2015) The aim of this study was to evaluate the prevalence of halitosis and its associated factors among students.
790 high school students, aged 14 to 18; 484 were boys and 306 were girls.
High school students of Kermanshah.
The questionnaire included questions about bad breath and other associated factors (demographic information, background diseases, oral and dental problems, decay-missing-filled (DMF) index).
Organoleptic evaluation was conducted.
The prevalence of halitosis in the organoleptic evaluation was 29.75% and higher in boys (32.6% male vs. 25.2% female) and 27.47% in self-perception (32.9% male vs. 19% female). The diagnostic agreement between organoleptic and self-perceived halitosis was moderate or poor. Background: Halitosis is a frequent condition that affects a large part of the population. Considered a "social stigma", it can determine a number of psychological and relationship consequences that affect people's lives. The purpose of this review is to examine the role of psychological factors in the condition of self-perceived halitosis in adolescent subjects and adulthood. Type of studies reviewed: We conducted, by the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines, systematic research of the literature on PubMed and Scholar. The key terms used were halitosis, halitosis self-perception, psychological factors, breath odor and two terms related to sociorelational consequences ("Halitosis and Social Relationship" OR "Social Issue of Halitosis"). Initial research identified 3008 articles. As a result of the inclusion and exclusion criteria, the number of publications was reduced to 38. Results: According to the literature examined, halitosis is a condition that is rarely self-perceived. In general, women have a greater ability to recognize it than men. Several factors can affect the perception of the dental condition, such as socioeconomic status, emotional state and body image. Conclusion and practical implication: Self-perceived halitosis could have a significant impact on the patient's quality of life. Among the most frequent consequences are found anxiety, reduced levels of self-esteem, misinterpretation of other people's attitudes and embarrassment and relational discomfort that often result in social isolation.

Rationale 3
Halitosis, commonly called bad breath, is a problem that can affect both the external, relational, social communication and internal, psychological sphere, with implications on perceived quality of life [1]. People are usually unaware of their breath, and when they become aware of it, they incorrectly attribute the cause of their condition. Halitosis is a frequent condition, present in 50-65% of the world population [2]. Although it is a significant source of discomfort, a precise estimation of prevalence is not possible because epidemiological studies are limited. This limitation could be determined by several factors, such as the absence of a standardized method for assessment of the disease, the difficulty in recognizing its presence and the likelihood that it is in some cases transient, which is why it is underreported in epidemiological data [3]. The problem of people with halitosis is that this condition can often remain unnoticed because people are generally unaware of the quality of their oral odor. Considered by Kolo [5] as a "social stigma", it could become an obsession that dominates a person's life, determining the onset of factors such as anxiety and psychosocial stress. One theme of studies on self-perceived halitosis shows that the problem is often not self-perceived [20,21]. Self-reported halitosis tends to be underestimated mainly because individuals may have difficulty in detecting their own smell or feel embarrassed to expose themselves, in line with the intimate dimension of the relationship with their mouth [22]. Subjects with a good body image pay more attention to their mouth and oral malodor [23]. Recent studies confirm that self-perception of halitosis may be related to a psychogenic or psychosomatic disorder and has a strong psychological impact [31,32].

2,3
Objectives 4 The aim of this work is to examine the role of psychological factors in the condition of self-perceived halitosis in adolescent subjects and adulthood. 1 methods

Protocol and registration 5
We used the following search terms: halitosis, self-perception halitosis, psychological factors, breath odor and two terms related to sociorelational consequences ("Halitosis and Social Relationship" OR " Social Issue of Halitosis"). In the initial search, we identified 3008 publications; after applying inclusion and exclusion criteria, we analyzed 38 studies. We used the following eligibility criteria: English language, publication in peer-reviewed scientific journals, quantitative information about self-perceived halitosis and oral hygiene. Articles were excluded based on title and abstract screen; article type of review article, editorial comment or case report; and year of publication prior to 2010.

4,5
Information sources 7 This review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses [33]. To identify the studies, we performed a systematic literature search on the PubMed, Scholar and ScienceDirect databases. The search was limited to studies written in English. We identified the literature from January 2010 to January 2020 using four key terms related to self-perceived halitosis, namely halitosis, self-perception halitosis, psychological factors and breath odor, and two terms related to sociorelational consequences ("Halitosis and Social Relationship" OR " Social Issue of Halitosis"). The articles from 1994 and 2001 were only cited to introduce the body image theory and to link it to the perception that each individual has of his or her own smell.

4,5
Search 8 Articles were selected by title and abstract; the entire article was read if the title and abstract were related to the specific issue of adolescence, adulthood and self-perceived halitosis and if the article potentially met the inclusion criteria. References of the selected articles were also examined in order to identify additional studies meeting the inclusion criteria.

4,5
Study selection 9 We performed a systematic literature search on the PubMed, Scholar and ScienceDirect databases. The search was limited to studies written in English. We identified the literature from January 2010 to January 2020 using four key terms related to self-perceived halitosis, namely halitosis, self-perception halitosis, psychological factors and breath odor, and two terms related to sociorelational consequences ("Halitosis and Social Relationship" OR " Social Issue of Halitosis").

5
Data collection process 10 Articles were selected online in relation to the title and abstracts; articles were read in full when titles and abstracts were consistent with the objective of our study. Following this procedure, we found 889 articles on the PubMed database, 1950 articles on Scholar and 169 articles on ScienceDirect; after applying the inclusion and exclusion criteria, the total number of relevant publications was reduced to 38.

5
Data items 11 Not specified.

Risk of bias in individual studies 12
Across the included studies in this review, a potential database bias should be considered. Only articles written in English language were used, which might have compromised access to articles published in other languages.

Summary measures 13
The list of search terms entered into the PubMed, Scholar and ScienceDirect search is described in Table 1. Table 1 Synthesis of results 14 The search in the PubMed, Scholar and ScienceDirect databases provided a total of 3008 articles; no further studies meeting the inclusion criteria were identified. After eliminating duplicates, further studies were excluded according to the inclusion and exclusion criteria. After screening, 38 studies were selected as appropriate for the present review.

Discussion
The studies analyzed focus on the importance of self-perception of halitosis and the consequences it has on the life of the individual. It is an oral health problem that could be prevented through appropriate oral hygiene practices and to which attention should be paid, given the influence it has on patients' quality of life. The subject's awareness of his or her condition leads to such anxiety that he or she obsessively uses appropriate instruments to eclipse the bad smell, such as sprays, chewing gum, pills or mouthwashes [38]. Although it is a significant condition for the individual, it is not easy to recognize or "self-perceive" it. A study conducted in Saudi Arabia and the United Kingdom [34] showed that 51.9% of the Saudi population and 54.9% of the UK population were aware of their halitosis. In contrast, a study conducted on the population of the Netherlands shows that only 4.2% were able to recognize their bad smell [35]. In individuals with halitosis, certain consequences have a significant impact on the individual. The reduction in self-confidence and self-esteem levels and the onset of depression and stress are the main consequences that can be observed in patients with this condition. The onset of social anxiety is also important, as it could lead the individual to estrangement and avoidance of social interactions. In a study [37], it has been shown that people with halitosis had relationship failures, in particular with individuals of the opposite gender; showed difficulties in achieving their goals; and exhibited compromised performance even in the workplace, considering this condition a "social handicap". The research obtained also allows us to affirm that, although halitosis causes considerable problems in the subject, it is often not treated but ignored or denied. Patients are not very optimistic about treatment. In the literature, it emerges that the self-perception of halitosis could determine the onset of symptoms such as anxiety, obsessive-compulsive disorders and paranoid ideation, and very often subjects misinterpret the attitude of people who relate to them. There is a need to introduce, together with the professional doctor, the intervention of specialists such as psychologists and psychiatrists to prevent consequences [17,36]. We believe that it is useful to work in a multidisciplinary mode in which one can intervene on both the oral condition and the psychological conditions of the patient to alter inadequate attitudes and wrong beliefs and to encourage the adoption of behaviors that can reduce the bad smell and improve patients' quality of life.

Limitations
This study suffers from several limitations: indeed, due to the relatively low number of studies on the topic and their great methodological heterogeneity, a proper formal quality assessment of each work was precluded. Therefore, selection bias was not properly addressed, which can impact the general interpretability of results. In general, care is required when interpreting the results of the cited studies, and further investigations are needed to clarify the relationship between self-perceived and objective halitosis.

Conclusions
This study has identified the importance of the consequences that the perception of bad breath has on the psychorelational side and, in general, on patients' quality of life. Literature studies have shown that women have, as a percentage, a greater awareness of their dental condition than men. Socioeconomic status is one of the factors that can influence self-perceived halitosis. Research has also led to an understanding of how body image and emotional state may be a variable that can influence perception. Oral hygiene measures can significantly reduce the bad smell. Oral health education must also be provided in many places, including private dental and medical clinics, and it is important that healthcare professionals, including general practitioners and health professionals, understand the etiology and critical factors in order to diagnose and treat patients appropriately. This review has reviewed the studies in the literature. The limitation of our study concerns the exclusive treatment of psychological factors implicated in halitosis at the expense of possible treatments. Data Availability Statement: The study did not report any data.