Effect of fixed orthodontic appliances on self-assessment and diagnosis of halitosis in undergraduate dental students.

BACKGROUND: The effects of fixed orthodontic therapy on the occurrence of halitosis are not yet fully understood. This study aimed to evaluate the effect of fixed orthodontic appliances on self-assessment and diagnosis of halitosis in undergraduate dental students.
MATERIALS AND METHODS: Sixty-two undergraduate dental students were included in this cross-sectional study. Two groups (n = 31 per group) were composed of participants with (study group) or without (control group) fixed orthodontic appliance. Halitosis self-assessment and clinical diagnosis were assessed using a visual analogic scale (VAS) and sulfur volatile compounds (SVCs) assessment, respectively. The subjective (VAS) and objective (SVC) malodor assessments were classified in absence, light, moderate, or severe malodor. Chi-square Pearson test and Spearman's correlation were applied for data analysis, with a significance level of 5%.
RESULTS: The use of fixed orthodontic appliances had no effect on self-assessment (P = 0.490) or clinical diagnosis (P = 0.610) of halitosis. Self-assessment was not significantly associated with the diagnosis of halitosis regardless the use of fixed orthodontic appliance (P ≥ 0.737). Male participants showed higher diagnosis of halitosis (P = 0.007). SVC measurements showed the absence of halitosis in 51.6% and 58.1% of participants with or without orthodontic appliances, respectively.
CONCLUSION: The use of fixed orthodontic appliances affected the self-assessment of halitosis but no SVC measurements. It was not verified a correlation between subjective and objective methods to diagnose halitosis in dental students. Copyright:

INTRODUCTION

Halitosis is an unpleasant change in the odor of the oral cavity which is originated from oral and nonoral sources.[12] This alteration interferes with the quality of life and interpersonal relationships and can lead to social withdrawal.[34] Moreover, halitosis is a clinical sign that some disorder is occurring and needs to be properly treated.[35] In this way, dental clinicians are the first-line professionals who must be able to identify this alteration.[35] Therefore, halitosis must be a concern during anamnesis and clinical examination since its complication and high prevalence (around 30%).[467]

Some clinical conditions can facilitate halitosis onset. Although halitosis may have a multifactorial source, orthodontic brackets can play an important role in oral malodor appearance[89] in patients under fixed orthodontic therapy.[1011] The placement of orthodontic devices leads to plaque accumulation and hinder access to good oral hygiene practices.[812] Thus, one of the major clinical challenges during orthodontic treatment is to improve the periodontal tissue condition and manage plaque accumulation and halitosis of the patients.[8]

There are three main methods for diagnosis of halitosis: self-assessment, organoleptic assessment, and sulfur volatile compound (SVC) level measurement.[13] While the organoleptic and SVC measurements are objective methods and demand a trained operator and appropriate device, the self-assessment is time saving and cost-effective.[1314]

It is important to note that patients' self-assessment of oral malodor is a complex issue that involves cognitive, emotional, and physiological factors.[1516] Taking that into account, most patients complaining of oral malodor may not exhibit a clinical diagnosis of halitosis.[1718] Besides, these patients tend to overestimate their oral malodor compared with an odor judgment from others.[192021]

The self-assessment of halitosis is limited since it is an evaluation only based on the perception of the individual.[22] However, it is still clinically relevant since takes into account any malodor that exerts a negative effect on the quality of life.[5] Previous studies have shown divergent findings regarding self-assessment of halitosis in dental students and the factors related to halitosis, as well as their impact on the quality of life.[1423] However, the role of the higher knowledge and concern about oral conditions by dental students than the general population[24] on self-assessment of halitosis was not fully investigated.

Pseudo-halitosis can be observed in many cases since halitosis is a complex disease affected by psychosomatic factors,[21] such as those situations where the individuals are exposed to risk factors of halitosis. The fixed orthodontic appliance provides an increased number of subgingival periodontitis-related pathogens.[25] Moreover, patients with periodontitis are more susceptible to have halitosis (three times higher odds).[26]

Thus, this study aimed to evaluate whether the self-assessment is clinically confirmed among dental students under fixed orthodontic treatment. The null hypotheses tested were that fixed orthodontic appliances do not affect (1) the self-assessment of halitosis; (2) the diagnosis of halitosis by SVC measurements; and (3) there is no correlation between self-assessment and clinical confirmation of halitosis in dental students.

MATERIALS AND METHODS

Ethical aspects

This study followed the ethical recommendations of the Declaration of Helsinki. It was submitted and approved by an institutional review board. The participants previously agree to participate and signed a free and informed consent form. Furthermore, the article was written according to the recommendations of the Strengthening the Reporting of Observational Studies in Epidemiology.[27]

Study design and sample

A comparative cross-sectional study was carried out in a higher educational institution in Teresina, Piauí, Brazil. For the sample size calculation, malodor prevalence of 65% and 30% in the patients with and without orthodontic appliance were, respectively, considered.[456] Significance level at 5% and test power of 80% were used. After calculation, 62 participants were necessary for the study.

A nonprobabilistic sample was obtained among all undergraduate dental students enrolled in the institution. For the study group (SG), eligibility criteria for the participants included the following: under orthodontic treatment for 6 months or more; at age 18 or older. The exclusion criteria were participants using systemic antimicrobial medications; smokers; with fixed and/or removable prostheses; undergone dental and/or oral surgery in the last 6 months; and absence of periodontal disease, which was confirmed by clinical examination. For the control group (CG), participants without orthodontic treatment and that never had submitted to orthodontic therapy before were considered eligible.

To prevent that odor by dietary and cosmetic sources that influence the halitosis self-assessment, the participants were instructed to refrain the use of scented personal products and tooth brushing on the morning of the appointment. They were also instructed to do not to eat spicy foods or onion/garlic-contained foods 48 h before the appointment. Refrain from eating at least 8 h and from drinking 3 h before the evaluation was requested. In addition, they avoided the use of chewing gum and oral rinsing at least 12 h before the appointment.[13]

Self-assessment evaluation

The self-assessment of halitosis was carried out as previously described by Rosenberg et al.[17] The participants were asked to smell the odor emanating from their mouth by cupping their hands over mouth and nose, exhaling through the mouth, and breathing in through the nose. After that, the odor self-assessment was recorded by the participant using a visual analogic scale (VAS). After to smell the odor, each participant marked the value corresponding to their self-assessment of the odor on a scale from 0 (no bad breath) to 10 (strong bad breath).

The odor self-assessment was classified in levels, corresponding to the points observed in the VAS. Thus, for point 0, the absence of odor was considered. Points between 1–3, 4–7, and 8–10 were considered as slight, moderate, and severe odor, respectively.

Sulfur volatile compounds assessment

For the diagnosis of halitosis, the SVCs and hydrocarbon gases from participants were detected using a portable device (Breath Checker Model HC-212SF, Tanita Corp, Inc, Japan), which is commonly used for objective diagnosis of halitosis[151617] by semiconductor measurement technology. In this device, sulfur gases and hydrocarbons present in the breath are detected for a small electrical current through the sensor in a fast, simple, and reliable way.[10]

For the SVC assessment, the participants were instructed to remain with their mouth closed, performing only nasal breathing for 3 min before the measurement. The diagnosis was performed bringing the sensor closer to participants' open mouth for 5 s. At the end of this time, the measurement was recorded and observed on the display. For each participant, the measurement was performed three consecutive times with no time interval. The highest obtained value was registered.

According to the manufacturer, the device classifies the odor in levels from 0 to 5. In this study, the odor was classified as the following: absence of odor (level 0); slight odor (levels 1 and 2); moderate odor (level 3); and severe odor (levels 4 and 5).

Data analysis

Data analysis was carried out using the Statistical Package for the Social Sciences (SPSS® for Windows® version 22.0 Inc., IL, Chicago, USA), with a significance level of 5%. A descriptive analysis of data was presented as frequency and percentage. Chi-square Pearson test was used to associate self-assessment and diagnosis of halitosis with independent variables (fixed orthodontic appliance use, sex, and age group) and to compare the levels of self-assessment and diagnosis of halitosis between the groups. Spearman's correlation was applied to associate self-assessment and diagnosis.

RESULTS

Data of 62 participants with (SG) or without (CG) fixed orthodontic appliances were obtained (n = 31/group). Most of the participants were female and the groups were paired by sex. The greater proportion of participants was in the 22–24 age group, with an average of 23.1 (±3.3) years old [Table 1].

Table 1

Participants of the study

Variables	Fixed orthodontic appliance
	With	Without
Sex
Male	10 (32.3%)	10 (32.3%)
Female	21 (67.7%)	21 (67.7%)
Age group
≤21 years	7 (22.6%)	1 (3.2%)
22-24 years	17 (54.8%)	25 (80.6%)
≥25 years	7 (22.6%)	5 (16.2%)

Table 2 shows the association between self-assessment and clinical diagnosis of halitosis with independent variables. Although with a similar frequency (n = 14) for both sexes, a greater proportion of male participants (70%) exhibited a clinical diagnosis of halitosis (P = 0.007). The use of fixed orthodontic appliance (P ≥ 0.490) or age group (P ≥ 0.176) was not associated with the presence of halitosis, either by self-assessment or by clinical diagnosis.

Table 2

Association between independent variables with self-assessment and clinical diagnosis of halitosis in undergraduate dental students

Variables	Clinical Diagnosis		P*	Self-assessment		P*
	Absence	Presence		Absence	Presence
Fixed orthodontic appliance
With	16 (51.6%)	15 (48.4%)	0.610***	6 (19.3%)	25 (80.7%)	0.490***
Without	18 (58.1%)	13 (41.9%)		4 (12.9%)	27 (87.1%)
Sex
Female	28 (66.7%)	14 (33.3%)	0.007**	7 (16.7%)	35 (83.3%)	0.868***
Male	6 (30%)	14 (70%)		3 (15%)	17 (85%)
Age group
≤21 years	11 (55%)	9 (45%)	0.962***	3 (15%)	17 (85%)	0.176***
22-24 years	15 (50%)	15 (50%)		3 (10%)	27 (90%)
≥25 years	8 (66.7%)	4 (33.3%)		4 (33.3%)	8 (66.7%)

*Chi-square Pearson test, Significance level at 5%; **P<0.05 - statistically significant; ***P>0.05 - non-statistically significant.

Most undergraduate dental students reported malodor. However, the use of fixed orthodontic appliance exhibited no effect on the levels of odor classification by self-assessment (P = 0.606). Similarly, the clinical diagnosis was not associated with the orthodontic appliance (P = 0.521). The absence of halitosis was clinically diagnosed for 51.6% and 58.1% of the participants with and without orthodontic appliances, respectively [Table 3].

Table 3

Level analysis of self-assessment and diagnosis of halitosis in undergraduate dental students with or without fixed orthodontic appliance

	Fixed orthodontic appliance		P*
	With	Without
Self-assessment
Abscence	6 (19.4%)	4 (12.9%)	0.606**
Slight malodor	8 (25.8%)	14 (45.2%)
Moderate malodor	16 (51.6%)	12 (38.7%)
Severe malodor	1 (3.2%)	1 (3.2%)
Diagnosis
Absence	16 (51.6%)	18 (58.1%)	0.521**
Slight malodor	1 (3.2%)	1 (3.2%)
Moderate malodor	9 (29.0%)	9 (29.0%)
Severe malodor	5 (16.1%)	3 (9.7%)

*Chi-square Pearson test, significance level at 5%; **P>0.05 - nonstatistically significant.

Spearman's correlation coefficients showed that self-assessment was not significantly associated with the halitosis diagnosis. This was seen in participants with (r = 0.016, P = 0.933) and without (r = 0.063, P = 0.737) fixed orthodontic appliance [Figure 1].

Figure 1

Correlation between self-assessment and clinical diagnosis of halitosis among undergraduate dental students with fixed orthodontic appliance. *SVC - Sulfur volatile compounds

DISCUSSION

This study evaluated the effect of fixed orthodontic treatment on self-assessment and clinical diagnosis of halitosis in undergraduate dental students. The participants exhibited high self-reported halitosis and low clinical confirmation. Besides, self-assessment and halitosis diagnosis were not associated with the use of fixed orthodontic appliances, and the correlation between self-assessment and clinical diagnosis was not confirmed. Thus, only the first null hypothesis was rejected.

Self-assessment of halitosis is a psychophysiological response with a multifactorial etiology and associated with the psychopathological profile of each individual.[22] In this study, a high rate of self-reported malodor was observed among undergraduate dental students (83.3% for females and 85% for males). This perception did not differ between sexes, age groups, or the use of fixed orthodontic appliances. These results suggest that dental students are possibly more sensitive to their oral odors and tend to even classify physiological odors as halitosis. Besides, the prevalence of self-reported malodor was higher than a previous study with dental students.[22] The differences in rates of malodor perception may be possibly associated with the method adopted. In the present study, a VAS was used, while in the study by Ashwath et al.,[22] the perception data were obtained through a questionnaire.

Our results suggest that the use of a fixed orthodontic appliance does not interfere with self-perception and clinical diagnosis of halitosis among undergraduate dental students. This finding can be explained because dental hygiene guidance is often provided to individuals undergoing orthodontic treatment since they present a higher number of visits to dental offices than those who are not under orthodontic therapy.[28] Besides, theoretically, before patients are submitted to the placement of orthodontic devices, they should be aware of the risks of this treatment, which involves halitosis. Thus, it can be inferred that these patients appear to be more cautious concerning halitosis. Moreover, the majority of people seeking orthodontic treatment are looking for increasing the esthetics of their teeth, which may show a patient profile concerned with oral hygiene practices.[29] In addition, our results were obtained from a sample of dental students, who have great knowledge and work directly in oral health promotion and hygiene measures guidelines, which can lead them to have a greater awareness of their oral health.[22]

In this study, a higher occurrence of halitosis was observed in male participants. This result agrees with other reports among dental students[3031] and can be justified by the fact that female students show more suitable oral hygiene practices. Although oral health conditions and oral hygiene practices were not evaluated in this study, Almas et al.[30] claimed that the lower self-assessment of oral malodor among females was associated with better oral hygiene practices, less self-reported malodor, and smoking habits than males. Similar results were observed by Setia et al.[31] where the lower prevalence of halitosis in female students was also justified by the best oral hygiene practices concerning their male peers.

The data observed for self-assessment were not clinically confirmed. Although the majority of participants self-reported halitosis, the clinical diagnosis confirmed the absence of halitosis in 51.6% and 58.1% of participants with and without orthodontic appliances, respectively. Besides, the occurrence of halitosis also did not differ between age groups and there was no correlation between self-perception and clinical diagnosis, regardless of the use or not of fixed orthodontic appliance. These results are similar to other studies in the literature.[3233] Individuals exposed for long periods to some odor can adapt to it and become desensitized, which may explain why there is no correlation between subjective and objective assessment of halitosis. Patients may not notice their oral odor after being desensitized by an adaptation process.[34] Besides, our study included dental students, who have more information about dental diseases and changes concerning the general population. This profile may justify that the participants overestimated the presence of oral malodor.

Although with a smaller proportion, a significant rate of participants with halitosis was observed. Humagain et al.[35] observed in a study among undergraduate students in different areas that most of the individuals (43.8%) reported that halitosis negatively impacted their social relationships. Moreover, oral hygiene instructions provided by professionals appear to positively affect the oral health-related quality of life in individuals with halitosis.[36] Thus, our findings point out the need for adopting oral hygiene measures and oral health promotion guidelines to the perception and occurrence of halitosis, regardless of other associated covariables.

The etiology of halitosis is multifactorial and remains unclear.[34] Recent studies have claimed the association of halitosis occurrence with high levels of anxiety and stress.[3738] The theory so-called microbial endocrinology states that the microorganisms responsible for malodor can interact with substances related to stress and/or anxiety and change their metabolism, virulence, and growth profile.[3738] It is known that dental students may have a high level of anxiety due to the phase of life they are going through, the workload of classes and disciplines, and the responsibility for starting to deal with patients can trigger peaks of stress.[39] Thus, these findings and our results highlight the importance to develop longitudinal studies that evaluate and clarify the role of several covariables commonly associated with the etiology of halitosis.

Fixed orthodontic appliances can affect the microbial diversity in the oral cavity since braces can promote bacterial adhesion, biofilm formation, and accumulation of anaerobic microorganisms.[40] SVCs, such as hydrogen sulfide (H2S) and methyl mercaptan (CH3SH), are the main components of oral malodor and are produced as end-products of the proteolytic processes of oral microorganisms. Gram-negative anaerobic bacteria are the predominant producers of H2S and CH3SH since they are the main pathway of proteolysis through the metabolism of sulfur-containing amino acids.[41] Thus, Gram-negative anaerobic bacteria play a crucial role in halitosis. In addition, the type of bracket used appears to not influence microbial colonization and the occurrence of halitosis under orthodontic treatment.[742] These previous findings corroborate with our results and suggest that dental students are very sensitive to oral odors which do not match with halitosis.

Our findings have some limitations and a careful analysis of the results is strongly recommended. It was not possible to recruit an equal proportion of participants regarding their sexes since dentistry courses in Brazil traditionally have a larger female audience. Another limitation remains on the fact that only a specific population was investigated (dental students). Previous studies have demonstrated that self-assessment of halitosis can underestimate the prevalence of this condition.[12543] However, these findings are based on the investigation of nondental students. Thus, our hypothesis was that dental students appear to have higher knowledge regarding oral conditions and familiarization of oral malodors than nondental students which could result in more accuracy of self-assessment of halitosis. However, further studies are needed to confirm the results and to investigate the correlation between self-assessment and diagnosis of halitosis among the general population.

CONCLUSION

The use of fixed orthodontic appliances affected the self-assessment of halitosis which was not clinically confirmed by the SVC measurements. It was not verified a correlation between subjective and objective methods to diagnose halitosis in dental students. Moreover, dental students appear to overestimate their oral malodor.

Financial support and sponsorship

This study was financed in part by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil – Finance Code 001.

Conflicts of interest

There are no conflicts of interest.