Snoring Symptoms and Obstructive Sleep Apnea Risk Factors Identified by Doctors of Dental Medicine

Abstract

Objective

To examine the association between snoring, a primary symptom of obstructive sleeps apnea (OSA) and patients’ age, sex, and anthropometric characteristics. The goal is to support dental medicine doctors in identifying individuals at increased risk of OSA.

Materials and methods

This retrospective cross-sectional clinical study included 795 participants. Data were collected on age, sex, and anthropometric measurements. Participants also completed the STOP questionnaire and the Epworth Sleepiness Scale. Overnight polysomnography was performed at the Clinical Hospital Center Split and the University of Split School of Medicine between 2018 and 2023.

Results

Participants who reported snoring were significantly heavier (96.5 ± 20.5 kg vs. 84.6 ± 19.3 kg) and had a higher BMI (31.3 ± 10.9 kg/m² vs. 27.2 ± 5.1 kg/m²) than those without snoring. They also had larger neck (41.5 ± 6.0 cm vs. 38.8 ± 4.5 cm), waist (107.8 ± 15.4 cm vs. 96.9 ± 15.4 cm), and hip (110.7 ± 12.3 cm vs. 106.0 ± 11.0 cm) circumferences (P < 0.001 for all). These participants also reported greater daytime sleepiness (Epworth Sleepiness Scale: 7.8 ± 4.9 vs. 5.9 ± 4.2; P < 0.001) and had significantly higher AHI values (32.8 ± 26.1 vs. 15.1 ± 17.5; P < 0.001), indicating more severe OSA.

Conclusion

Snoring is significantly associated with higher body mass, increased BMI, larger body circumferences, greater daytime sleepiness, and more severe OSA. It may serve as a useful clinical marker for dentists when identifying patients at elevated risk for OSA. Among the examined variables, BMI, AHI, and age were significant predictors of snoring, while sex did not show a statistically significant influence.

Introduction

Snoring is tipically defined as a respiratory sound that occurs during inhalation or exhalation while sleeping, caused by vibrations of the oropharyngeal walls due to reduced upper airway patency (1). It can be described both quantitatively,—measured in decibels (dB)—and qualitatively, as one of the hallmark symptoms of obstructive sleep apnea (OSA) (2).

Obstructive sleep apnea (OSA) is the most prevalent sleep-related breathing disorder, affecting approximately 1 in 20 adults. It is characterized by recurrent episodes of partial or complete upper airway collapse, resulting in disrupted sleep architecture and decreased arterial oxygen saturation (3). The etiology of OSA is multifactorial and includes a range of interrelated pathologies and risk factors such as obesity (neck circumference >41 cm, BMI >30 kg/m²), advanced age, male sex, anatomical variations of hard and soft tissues, postmenopausal status, smoking, and genetic predisposition (4). The severity of OSA is assessed using the apnea-hypopnea index (AHI), which reflects the average number of apnea and hypopnea events per hour of sleep (5). Clinically, OSA presents with symptoms such as snoring, daytime sleepiness, night sweats, restless sleep, heartburn, morning headaches, and insomnia. These symptoms often evolve gradually, which may lead to delayed diagnosis after significant health deterioration. Despite its high prevalence, OSA frequently remains undiagnosed.

Dental clinics can play a pivotal role in the early detection of patients at risk for OSA. Numerous studies have highlighted the potential of dentists to recognize symptoms and risk factors associated with OSA, using tools such as the STOP questionnaire in routine clinical practice. This allows for early identification of high-risk individuals and timely referral to specialized centers (6, 7). Alongside detailed patient history, and screening tools like the STOP questionnaire and the Epworth Sleepiness Scale, overnight polysomnography remains the "gold standard" for diagnosing OSA (6, 8).

Before selecting a treatment approach—whether conservative or surgical—it is essential to determine the cause and severity of the airway obstruction through a multidisciplinary evaluation involving various medical specialties, including dental professionals. For patients diagnosed with mild to moderate OSA, or those intolerant to continuous positive airway pressure (CPAP) therapy, intraoral appliances such as mandibular advancement devices (MAD) or tongue retaining devices (TRD) are preferred conservative treatment options (9, 10). A MAD (Figure 1) is a custom-made device that maintains the lower jaw in a protruded position during sleep, keeping the airway open. TRDs, on the other hand, hold the tongue forward to prevent airway obstruction (11). According to the American Academy of Sleep Medicine (AASM), oral appliances are the standard treatment for primary snoring in adults, reducing the frequency and intensity of snoring and improving sleep quality for patients and their partners (12, 13).

Figure 1.

Illustration of the use of an oral appliance that keeps the airway open (45)

In addition to their therapeutic role, dental professionals are well-positioned to identify patients at high risk of sleep-disordered breathing. Dentists routinely evaluate patient age, sex, and anthropometric features, and have direct access to assess the oropharyngeal region, which may present anatomical or pathological changes contributing to airway obstruction. Moreover, OSA, which is often associated with snoring, leads to mouth breathing, dry mouth, and altered salivary pH, thus negatively impacting oral health and contribute to conditions such as gingivitis, periodontitis, dental erosion and overall tooth loss (14-22). Research has shown that patients with untreated OSA often present with increased dental wear and a higher incidence of cavities, which can result in more frequent tooth fractures compared to individuals without sleep-disordered breathing (21, 23). This underscores the importance of early detection and management of OSA to prevent or mitigate its detrimental effects on oral health (23-25). Al-Maweri et al. reported that oral appliances not only improve sleep quality, but also reduce the incidence of dry mouth and improve salivary flow supporting the link between OSA treatment and oral health. These findings reinforce the important role of dental professionals in OSA care (26).

Despite their strategic role in identifying at-risk individuals, dental professionals in Croatia often lack formal education on this topic. This gap may explain the growing emphasis in international guidelines, issued by national dental associations, on the importance of dentist involvement in the diagnosis and management of OSA patients (27-29). Such education is essential to ensure that dentists are equipped to identify potential OSA cases early, provide appropriate referrals, and even offer interventions such as oral appliances for patients with mild to moderate cases.

The aim of this study was to examine the relationship between snoring—as one of the key symptoms of OSA—and age, gender, and anthropometric characteristics, with the goal of enhancing dentist awareness and improving identification of high-risk patients.

We hypothesize that:

• 1 Snoring is associated with higher body weight, BMI, increased neck, waist, and hip circumferences.

• 2 Snoring is more frequent among older individuals and males.

Materials and methods

Procedures

This retrospective cross-sectional clinical study included a total of 795 participants. Data on age, gender, and anthropometric characteristics were collected, followed by an analysis of previously completed STOP questionnaires and the Epworth Sleepiness Scale. Additionally, results from overnight polysomnographies performed at the Clinical Hospital Center Split and the University of Split School of Medicine between 2018 and 2023 were analyzed (Class 003-08/22-03/003, Reg. No. 2181-198-03-04-22-0029).

Sample

The study included 795 participants, comprising 515 men (65%) and 280 women (35%), with a mean age of 54.74 ± 12.93 years. Upon arrival at the Clinical Hospital Center Split, and after providing informed consent, each participant's age, gender, and anthropometric measurements (height, weight, BMI, neck, waist, and hip circumference), as well as relevant medical conditions, were recorded by a certified technician.

All participants then completed the STOP questionnaire (Snoring, Tiredness, Observed apnea, high Blood Pressure) and the Epworth Sleepiness Scale, both translated and validated in Croatian (30). Inclusion criteria encompassed patients aged 18 to 75 who had been referred for polysomnography and did not have comorbid conditions that could affect the study results. Exclusion criteria included central sleep apnea, central hypoventilation syndromes, obesity hypoventilation syndrome, known CPAP users, and incomplete medical records.

The STOP questionnaire includes questions on snoring, fatigue, breathing cessation during sleep, and high blood pressure, with "YES" or "NO" answers (31). Two or more positive responses indicate an increased risk for OSA. The extended STOP-BANG version incorporates additional items on BMI, age, neck circumference, and gender (32).

The Epworth Sleepiness Scale allows participants to self-assess their level of daytime sleepiness during routine activities (0 = no need to sleep, 1 = slight, 2 = moderate, 3 = high likelihood of falling asleep). A total score above 10 indicates excessive daytime sleepiness. Croatian version of the scale, developed by the team at the University of Split School of Medicine and the Clinical Hospital Center Split, includes linguistic and cultural adaptations to ensure clarity and relevance for the Croatian population. It meets statistical criteria for reliability and validity, providing consistent and comparable assessments with international standards (30).

After completing the questionnaires, participants underwent overnight polysomnography (PSG), considered the "gold standard" for diagnosing OSA, at the Sleep Medicine Center of the Clinical Hospital Center Split. The Alice 5LE device (Philips Respironics, Eindhoven, Netherlands) was used. Data were analyzed by a trained technician, and diagnoses and further instructions were provided by a somnologist. The study recorded electroencephalography (EEG), electrooculography (EOG), electrocardiography (ECG), electromyography (EMG) of the chin and lower limbs, airflow, chest and abdominal movements, snoring, and pulse oximetry, all under video surveillance (33, 34).

Statistical Analysis

Continuous variables were presented as mean ± standard deviation, and categorical variables as counts and percentages. Statistical analysis was performed using MedCalc software (MedCalc Software, Mariakerke, Belgium, version 11.5.1.0). All relevant assumptions were verified, including data normality, sample independence, and absence of significant outliers.

Chi-square tests were used for categorical variables, and the independent samples t-test was used for continuous variables. Multivariate logistic regression was applied to develop a model linking snoring symptoms with anthropometric and polysomnographic variables, including age, gender, BMI, and AHI. The significance level was set at P < 0.05.

Results

Of the 795 participants, 515 (65%) were men and 280 (35%) were women. There was no statistically significant age difference between sexes (54.10 ± 13.17 vs. 55.19 ± 13.44 years, P = 0.271). As shown in Table 1, men were significantly taller (182.35 ± 25.27 cm vs. 166.9 ± 9.74 cm, P < 0.001), heavier (100.03 ± 18.17 kg vs. 80.44 ± 19.84 kg, P < 0.001), had a higher BMI (30.63 ± 10.13 kg/m² vs. 29.06 ± 9.06 kg/m², P = 0.033), and larger neck (42.99 ± 5.42 cm vs. 36.70 ± 3.67 cm, P < 0.001) and waist circumferences (112.10 ± 53.62 cm vs. 97.49 ± 17.05 cm, P < 0.001) than women.

Table 1. Demographic and Anthropometric Characteristics of the Participants.

Variable	Total	Men	Women P*
	N=795	N=515	N=280
Age (years)	54.74±12.93	54.10±13.17	55.19±13,44	0.271
Height (cm)	176.96±22.43	182.35±25.27	166.9±9.74	<0.001
Weight (kg)	93.22±20.76	100.03±18.17	80.44±19.84	<0.001
BMI (kg/m2)	30.10±9.79	30.63±10.13	29.06±9.06	0.033
Neck circumference (cm)	40.79±5.73	42.99±5.42	36.70±3.67	<0.001
Waist circumference (cm)	106.62±44.48	112.10±53.62	97.49±17.05	<0.001
Hip circumference (cm)	109.27±12.18	109.04±10.69	109.82±14.58	0.497
ESS score	7.17±4.88	7.21±4.80	7.16±5.02	0.876
STOP, N (%)
Has risk	603 (76)	402 (78)	204 (73)
No risk	187 (24)	113 (22)	76 (27)

Among all participants, 556 (73%) reported subjective snoring symptoms, while 202 (27%) did not report snoring symptoms. Compared to non-snorers, individuals with snoring were significantly heavier (96.5 ± 20.5 kg vs. 84.6 ± 19.3 kg, P < 0.001), had higher BMI (31.3 ± 10.9 kg/m² vs. 27.2 ± 5.1 kg/m², P < 0.001), and exhibited greater neck (41.5 ± 6.0 cm vs. 38.8 ± 4.5 cm, P < 0.001), waist (107.8 ± 15.4 cm vs. 96.9 ± 15.4 cm, P < 0.001), and hip circumferences (110.7 ± 12.3 cm vs. 106.0 ± 11.0 cm, P < 0.001) (Table 2). They also scored significantly higher on the Epworth Sleepiness Scale (7.8 ± 4.9 vs. 5.9 ± 4.2, P < 0.001), indicating greater daytime sleepiness. No significant differences were found in the prevalence of chronic diseases between the groups (Table 2).

Table 2. Demographic and Anthropometric Characteristics of Participants Based on Snoring Symptom.

Variable	Snoring YES	Snoring NO P*
	N=556	N=202
Age (years)	55.9±11.6	51.2±15,4	<0.001
Gender N (%) M	377 (67)	119 (59)
F	179 (33)	83 (41)
Height (cm)	177.4±25.9	175.9±9.6	0.448
Weight (kg)	96.5±20.5	84.6±19.3	<0.001
BMI (kg/m2)	31.3±10.9	27.2±5.1	<0.001
Neck circumference (cm)	41.5±6.0	38.8±4.5	<0.001
Waist circumference (cm)	107.8±15.4	96.9±15.4	<0.001
Hip circumference (cm)	110.7±12.3	106.0±11.0	<0.001
ESS score	7.8±4,9	5.9±4.2	<0.001
Hypertension	265 (48)	64 (32)	15.156†
Diabetes	73 (13)	18 (9)	2.097†
Depression	73 (13)	24 (12)	0.074†
Asthma	58 (10)	10 (5)	4.738†
GERD	177 (32)	53 (26)	2.220†

Values are presented as mean ± standard deviation, gender affiliation is presented as percentage

Student’s t-test

†Chi-square test

BMI – Body Mass Index

ESS – Epworth Sleepiness Scale

STOP – Questionnaire for assessing the risk of obstructive sleep apnea (Snoring, Tiredness, Observed apnea, high blood Pressure)

Polysomnography revealed that individuals with prominent snoring symptoms had more severe forms of OSA, as indicated by significantly higher AHI scores (32.8 ± 26.1 vs. 15.1 ± 17.5, P < 0.001). These participants also had elevated AHI values in both REM and non-REM sleep (35.2 ± 24.8 vs. 20.1 ± 19.3, P < 0.001) and experienced more frequent episodes of central, mixed, and obstructive apneas, as well as hypopneas (Table 3).

Table 3. Polysomnographic Findings in Participants Based on Snoring Symptom.

Variable	Snoring YES	Snoring NO P*
	N=556	N=202
AHI	32.8±26.1	15.1±17.5	<0.001
AHI REM	35.2±24.8	20.1±19.3	<0.001
AHI nonREM	31.8±26.8	14.1±18.0	<0.001
Sleep stage distribution
Stage N1	4.0±4.7	4.3±4.9	0.517
Stage N2	74.3±10.7	71.1±9.9	<0.001
Stage N3	7.4±7.0	9.4±7.8	<0.001
REM stage	14.3±7.0	15.3±6.6	0.088
Types of apnea
Central apnea (N)	9.1±17.3	5.1±11.6	0.002
Obstructive apnea (N)	93.5±119.9	31.1±66.1	<0.001
Mixed apnea (N)	20.5±46.5	6.8±27.4	<0.001
Hypopnea (N)	90.3±73.4	51.2±52.6	<0.001
Blood oxygen saturation
Lowest blood oxygen saturation (%)	77.9±14.8	86.2±10.10	<0.001
Sleep position
Left side	107.4±96.9	86.4±84.4	0.006
Right side	52.6±70.2	59.3±72.3	0.245
Back	200.6±115.7	194.3±111.1	0.522
Chest/Prone	13.2±34.6	19.7±45.1	0.036

Values are presented as mean ± standard deviation; blood oxygen saturation is presented as percentage.

Student’st-test

AHI-Apnea-HypopneaIndex

REMsleepstage–RapidEyeMovementsleepstage

non-REM sleep stage – Non-Rapid Eye Movement sleep stage

Snoring participants spent more time in the N2 sleep stage (74.3 ± 10.7 vs. 71.1 ± 9.9 min, P < 0.001) and less time in N3 sleep (7.4 ± 7.0 vs. 9.4 ± 7.8 min, P < 0.001). They also slept longer on their left side (107.4 ± 96.9 vs. 86.4 ± 84.4 min, P = 0.006) and less on their stomach (13.2 ± 34.6 vs. 19.7 ± 45.1 min, P = 0.036). Furthermore, they had significantly lower minimum oxygen saturation levels (77.9 ± 14.8% vs. 86.2 ± 10.1%, P < 0.001).

In the logistic regression model, snoring was set as the dependent variable. The analysis showed that snoring symptoms were most strongly predicted by increased BMI, higher AHI values, and older age, whereas gender was not a significant predictor (Table 4).

Table 4. Logistic Regression of the Subjective Snoring Symptom and AHI, Age, Gender, and Body Mass Index (BMI) as Predictors.

		OR	CI 95%	P
R2	14.2%
P	<0.001
Variables
AHI		1.03	1.02 do 1,04	<0.001
Age		1.02	1.01 do 1.03	0.006
Gender (men)		1.01	0.70 do 1,47	0.944
BMI		1.06	1.02 do 1,10	0.003

AHI–Apnea-HypopneaIndex

ITM – Body Mass Index (BMI)

Discussion

The results of this study support previous findings suggesting a relationship between the subjective symptom of snoring and obstructive sleep apnea (OSA), particularly in association with increased body mass index (BMI), neck circumference, and higher apnea-hypopnea index (AHI) values. While our data demonstrated a strong correlation between snoring and AHI values, similar studies—such as Bernstein et al.—have shown that not all individuals who snore are necessarily diagnosed with clinically significant OSA. This highlights the complexity of using snoring as a standalone diagnostic indicator and underscores the need for comprehensive diagnostic assessments to identify individuals at increased risk for OSA (35). Differences in study design, sample characteristics, and the inherently subjective nature of self-reported symptoms likely contribute to the variability in findings across studies.

Our findings align with those of Wickramasinghe et al., who also reported associations between obesity, elevated BMI, and male sex with a higher risk of OSA (36). However, although our study observed a higher frequency of snoring among men diagnosed with OSA, sex was not identified as a statistically significant factor influencing the frequency of snoring symptoms. This contrasts with the findings of Al-Jewair et al., who reported a significantly higher prevalence of snoring among men (37). These discrepancies may stem from methodological differences, particularly in the measurement of snoring—subjective self-report versus objective polysomnography. Al-Jewair et al. also noted significantly larger neck circumferences among men, supporting the role of anatomical differences in OSA pathogenesis. Consistent with this, our study found that participants who snored not only had higher BMI but also larger neck, waist, and hip circumferences, reinforcing the importance of physical examination and comprehensive history-taking in identifying high-risk patients.

Our data further corroborate findings by Yildirim et al., who emphasized the association between neck circumference and elevated AHI values, suggesting that neck circumference may be an independent risk factor for OSA, beyond general obesity (38). Similarly, Quintana-Gallego et al. found a higher frequency of snoring among men, while women were more likely to report a negative impact of snoring on quality of life and daily functioning (39). These gender-based perceptual differences may reflect sociocultural influences, where women may view snoring as more disruptive, whereas men may underreport or be less affected by such symptoms. This raises broader questions about the influence of social attitudes on symptom reporting and health-seeking behavior.

Our findings also confirmed a statistically significant association between snoring and increased daytime sleepiness, which is consistent with previous literature. However, some studies have shown that daytime sleepiness is more prevalent among men and not clearly linked to age or BMI (40-42). This inconsistency may be due to variability in measurement approaches (subjective questionnaires vs. objective sleep studies) or the confounding effects of other factors such as sleep quality or unrecognized comorbidities.

Research by Cruz et al. and Hofauer et al. further supports the association between snoring and increased cardiovascular risk, as well as the higher prevalence of primary snoring in men (43, 44). Despite these findings, our data did not support sex as a significant predictor of snoring frequency. Instead, BMI, AHI values, and older age emerged as the strongest predictors of both snoring and OSA risk. The noted methodological differences in snoring assessment and the relatively homogenous composition of our study sample may help explain the divergence from prior studies.

This study underscores the need for further research to deepen our understanding of the interplay between snoring, OSA, and other risk factors, including psychological, physiological, and sociocultural variables. A standardized approach to assessing snoring symptoms is essential for improving diagnostic consistency and accuracy. Moreover, early identification and monitoring of snoring are crucial for preventing OSA-related complications. Further research is needed to focus on longitudinal tracking of snoring symptoms and their progression into OSA, paying particular attention to lifestyle factors, genetic predispositions, and the effectiveness of early interventions.

The strengths of this study include a large sample size, the use of validated and standardized screening tools (STOP and Epworth questionnaires), and objective diagnosis via polysomnography, supported by robust multivariate statistical analyses.

However, several limitations must be acknowledged. These include: inability to establish causation, reliance on self-reported snoring symptoms; potential selection bias, given that participants were already referred for polysomnography; insufficient data on other relevant risk factors; and data collected from a single institution, which may limit the generalizability of findings to the wider population (45-47).

Conclusions

Owing to regular check-ups and direct access to the oropharyngeal region, dental medicine doctors play a key role in the early identification of patients at risk for OSA. Participants who reported snoring had significantly higher body mass, BMI, and larger neck, waist, and hip circumferences than those who did not. Snoring participants exhibited greater daytime sleepiness, as indicated by higher scores on the Epworth Sleepiness Scale. AHI values were significantly higher among snoring participants in both REM and non-REM sleep stages. Men diagnosed with OSA had larger neck and waist circumferences and higher BMI compared to women. No significant association was found between the presence of chronic diseases and snoring symptoms. BMI, AHI values, and age were the most significant predictors of snoring and OSA risk, whereas sex did not show a statistically significant impact.