Localization of pain in patients with probable bruxism: a cross-sectional pain-drawing and heat-map analysis

Abstract

Purpose

The heat-map method is a useful tool for spatially assessing pain distribution. This study aimed to determine pain distribution in patients with probable bruxism using heat maps generated from pain drawings and to examine the relationship between pain intensity, pain localization, and sociodemographic and behavioral factors.

Method

A total of 200 patients with probable bruxism (123 females, 77 males; age range: 18–70 years; mean age: 34.9 ± 12.6 years) were included. Probable bruxism was defined based on positive self-report and clinical evidence of non-functional dental wear/attrition. The study data were obtained from patients who attended our clinic between 2024 and 2025. Sociodemographic and behavioral data, including age, sex, systemic disease, education, occupation, marital status, sleep pattern, smoking, and alcohol use, were recorded. Templates depicting seven anatomical regions, including the intraoral region, right/left and anterior/posterior head–neck regions, and anterior/posterior upper extremities, were used. Patients colored the areas where they perceived pain. The frequency of marked boxes was calculated and used to generate heat maps. Pain intensity was evaluated using an 11-point Numerical Rating Scale (NRS). Data were analyzed using SPSS version 21, and p < 0.05 was considered statistically significant.

Results

Pain was most frequently localized to the right (n = 700) and left (n = 610) head–neck regions, whereas the intraoral region showed the lowest frequency (n = 143). NRS scores were significantly higher in females (p = 0.002) and in patients with self-reported irregular sleep patterns (p < 0.001). No significant associations were found between NRS scores and alcohol use, smoking, education, occupation, marital status, systemic disease, or age (p > 0.05).

Conclusions

In patients with probable bruxism, pain was predominantly localized to the head–neck region. Female sex and self-reported irregular sleep patterns were associated with higher perceived pain intensity.

Introduction

Bruxism, characterized by repetitive jaw-muscle activity such as clenching or grinding of the teeth, is a common parafunctional behavior that can occur during sleep or wakefulness [1, 2]. It is widely recognized as a multifactorial condition associated with physical, psychological, and behavioral factors, including stress, anxiety, occlusal discrepancies, and sleep disorders [3]. Chronic bruxism has been associated with a variety of complications, such as tooth wear, temporomandibular joint disorders (TMD), muscle hypertrophy, and pain in the orofacial region [4].

Pain is a multidimensional phenomenon that can be evaluated through various methods, including self-reporting, behavioral indicators such as vocalizations, facial expressions, and body movements, as well as physiological responses. Among these, patient-reported outcomes are widely regarded as the gold standard for pain assessment in clinical settings [5]. Pain associated with bruxism is often diffuse, subjective, and difficult to quantify, particularly when it extends beyond the intraoral structures into the surrounding musculature and cervical regions. Bruxist patients generally complain of muscle tension in the face, jaw, frontotemporal region, and pain in the preauricular region or ear [6].

Although several studies [7–9] have evaluated the intensity of pain in bruxist individuals, to the best of our knowledge, no studies have investigated the spatial characteristics and localization of this pain using visual methods. Previous studies [10, 11] utilizing pain drawings in patients with TMD have revealed that pain often extends beyond the temporomandibular region to the head, neck, shoulders, and lower back, suggesting a broader spatial distribution that may reflect central sensitization or musculoskeletal comorbidities. Incorporating such an approach in the assessment of bruxist individuals may contribute to a more holistic understanding of pain patterns and support the development of more comprehensive treatment strategies.

Traditional methods of pain evaluation rely heavily on self-reported pain scales [12–14], which lack spatial specificity. In this context, pain-drawing techniques have gained attention for their capacity to visually represent pain localization and distribution in a standardized manner. When combined with heat-map analysis, these drawings can provide standardized and reproducible representations of spatial pain patterns across larger patient groups. This study aims to analyze the distribution of pain in bruxist patients by generating a heat map derived from pain-drawing templates. Additionally, the study investigates the association between pain localization and various sociodemographic variables, offering a novel approach to pain assessment in bruxism. We hypothesized that pain reported by patients with probable bruxism would predominantly localize to the head and neck regions and that female sex and irregular sleep would be associated with higher pain severity.

Methods

Study design-setting and participants

This was an observational, cross-sectional study conducted at the Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Necmettin Erbakan University, Konya, Türkiye. The study was conducted in alignment with the principles outlined in the Declaration of Helsinki, incorporating all required protocols and amendments. Ethical compliance of the research was reviewed and approved by the Ethics Committee of the Faculty of Dentistry, Necmettin Erbakan University (Approval No: 2024/370). Informed consent was obtained from all participants prior to their inclusion in the study.

This study was conducted between 2024 and 2025. The participants were recruited from patients presenting to our clinic with pain complaints. A total of 200 volunteer patients (123 females, 77 males; age range: 18–70 years) were enrolled in the study. Bruxism status was classified according to the international consensus on bruxism assessment. A positive response to at least one of the screening questions was considered indicative of self-reported bruxism [15, 16]. However, participants were not classified as having probable bruxism based on self-report alone. Probable bruxism was defined as the combination of positive self-report and clinical findings, including non-functional dental wear/attrition observed during intraoral examination [16]. Definite bruxism requires instrumental confirmation, such as polysomnographic or electromyographic assessment; therefore, the present study did not aim to establish a definite bruxism diagnosis.

To fulfill the self-report component, participants were required to provide a positive response to at least one of the following screening questions [17]:

• ✓ “Do you think you have a habit of clenching or grinding your teeth?”

• ✓ “Has anyone told you that you grind your teeth during sleep?”

• ✓ “Do you frequently experience morning headaches?”

• ✓ “Do you feel pain in your jaw or temporomandibular joint (TMJ) area upon waking?”

Patients were included if they fulfilled the criteria for probable bruxism based on positive self-report and clinical evidence of non-functional dental wear. Since the primary aim of this study was to evaluate the pain reported by symptomatic patients who met the criteria for probable bruxism, masticatory muscle pain or myogenic discomfort was not considered an exclusion criterion. Therefore, patients with muscle-related pain clinically compatible with probable bruxism were not excluded solely on this basis.

However, patients with clinically evident joint-related temporomandibular disorders were excluded, as these conditions could independently affect pain localization and confound the interpretation of bruxism-related pain patterns. Joint-related TMDs included arthralgia, disc displacement with or without limited mouth opening, degenerative joint disease, subluxation, developmental joint disorders, benign or malignant lesions involving the temporomandibular joint, and infectious or inflammatory joint conditions. These conditions were evaluated through detailed history taking, clinical examination, and radiological assessment when indicated, according to the DC/TMD framework [18].

In addition, individuals with trigeminal neuralgia, neurological disorders involving the temporal or orofacial region, ongoing psychiatric treatment, substance or medication abuse, or other primary orofacial pain conditions that could independently explain the reported pain distribution were excluded.

Variables

The primary outcome was the spatial distribution of pain, assessed via heat map analysis. The secondary outcome was pain intensity, measured by NRS. Independent variables included age, sex, systemic disease, educational level, occupation, marital status, sleep pattern, smoking, and alcohol consumption.

Data collection

Participants were asked to complete a sociodemographic questionnaire through face-to-face interviews. Information collected included age, gender, systemic diseases, educational level, occupation, marital status, sleep patterns, smoking and alcohol consumption habits, and presence of comorbid pain outside the target regions. Sleep pattern was assessed using a single self-reported question asking participants whether they perceived their sleep as regular or irregular (yes/no).

Pain intensity assessment

Pain intensity was assessed using an 11-point Numerical Rating Scale (NRS). Participants were asked to rate their perceived pain intensity on a scale from 0 to 10, where 0 indicated “no pain” and 10 indicated the “worst imaginable pain.” Higher scores indicated greater pain intensity.

Pain drawing and heat map generation

Pain localization was evaluated using a pain drawing method. A 210 × 297 mm acetate template was used, depicting seven anatomical regions: intraoral area, right/left and anterior/posterior head-neck, and anterior/posterior upper extremities. Each region was subdivided into 120 small boxes (12 rows × 10 columns). Patients were instructed to mark the boxes corresponding to the areas where they experienced pain. The frequency of marked boxes was aggregated across all patients to generate a spatial heat map of pain distribution.

Patient-marked boxes on the physical templates were manually digitized into a Microsoft Excel grid, with each box coded as 1 if marked and 0 if unmarked. Marked-box frequencies were calculated for each anatomical region by summing the coded values across all patients. These frequencies were then used to generate spatial heat maps of patient-reported pain distribution. A standardized color scale with equal intervals of 10.96 units was applied, and the corresponding colors were manually transferred onto the digital template according to the calculated frequencies. No specialized heat-map software was used.

To assess the reliability of the digitization process, both researchers independently coded a subset of 40 patients, corresponding to 20% of the sample. Inter-rater agreement was high, with a Cohen’s κ value of 0.94. Minor discrepancies between raters were primarily related to borderline markings, such as partially filled or overlapping boxes, and were resolved by consensus.

Statistical analysis

All data were analyzed using IBM SPSS Statistics version 21 (SPSS Inc., Armonk, NY, USA). Descriptive statistics were used to summarize mean and standard deviation. Spearman’s rank correlation coefficient was used to assess the correlation between age and NRS scores. The Kruskal–Wallis and Mann–Whitney U tests were used to investigate the relationship between NRS scores and sociodemographic parameters. A p-value < 0.05 was considered statistically significant. The sample size of 200 patients was determined to ensure both descriptive precision and statistical power. For the primary objective of generating a heat map, a sample of 200 provides a margin of error of approximately ± 6.9% at a 95% confidence level, ensuring high precision in visualizing pain distribution frequencies. Additionally, a post-hoc power analysis was conducted for the secondary analytical objectives using G*Power software (version 3.1.9.7; University of Düsseldorf, Germany). For the comparison of NRS scores between genders and sleep patterns, the study achieved a statistical power (1-β) of 0.88 and 0.98, respectively (α = 0.05), exceeding the recommended threshold of 0.80.

Results

Participant characteristics

Among the 200 included patients, all participants fulfilled the criteria for probable bruxism based on a combination of positive self-report and clinical evidence of non-functional dental wear/attrition. Regarding the self-report component, 146 patients reported a habit of clenching or grinding their teeth, 73 reported being told that they grind their teeth during sleep, 127 reported frequent morning headaches, and 124 reported jaw or TMJ-area pain upon waking. Since participants could respond positively to more than one screening question, these categories were not mutually exclusive.

The study sample consisted of 123 females and 77 males, with a mean age of 34.9 ± 12.6 years. Of the 200 patients, 175 were systemically healthy, while 25 had systemic diseases as presented in Table 1. The mean NRS value obtained in the study was 3.16 ± 2.27. NRS scores were significantly higher in women and those with irregular sleep patterns (p < 0.05). No significant associations were found between NRS scores and alcohol use, smoking, education, occupation, marital status, systemic disease, or age (p > 0.05) (Table 1).

Table 1.

Participant characteristics

Variable	Category	Frequency (n)	Percent (%)	NRS (mean ± SD)	p
Systemic disease	None	175	87.5	3.07 ± 2.23
	Cardiovascular	9	4.5	3.22 ± 2.48
	Neurological	1	0.5	4.00 ± 0.00	0.185
	Endocrine	13	6.5	4.00 ± 2.79
	Respiratory	2	1.0	5.00 ± 1.41
Educational status	No education	5	2.5	1.20 ± 0.83
	Primary school	63	31.5	3.51 ± 2.51	0.129
	High school	61	30.5	3.08 ± 2.15
	University	71	35.5	3.06 ± 2.17
Occupation	Private sector	46	23.0	2.65 ± 2.00
	Public sector	27	13.5	3.63 ± 2.29	0.105
	Self-employed	13	6.5	2.31 ± 2.13
	Not working	114	57.0	3.35 ± 2.35
Marital status	Married	128	64.0	3.31 ± 2.32	0.224
	Single	72	36.0	2.89 ± 2.17
Regular sleep	Yes	72	36.0	2.29 ± 1.90	0.000*
	No	128	64.0	3.65 ± 2.33
Alcohol use	Yes	5	2.5	2.40 ± 0.89	0.666
	No	195	97.5	3.18 ± 2.29
Smoking	Yes	66	33.0	2.70 ± 1.94	0.060
	No	134	67.0	3.39 ± 2.39
Gender	Women	123	61.5	3.55 ± 2.36	0.002*
	Man	77	38.5	2.53 ± 1.98
Age range	18–24	55	27.5	2.60 ± 1.94	0.284
	25–34	49	24.5	3.39 ± 2.48
	35–44	51	25.5	3.47 ± 2.46
	45–54	27	13.5	3.63 ± 2.46
	55–70	18	9.0	2.67 ± 1.32

SD Standard deviation, NRS Numerical Rating Scale

*Significance level is at p < 0.05

Pain distribution

The percentages of the boxes marked by the 200 patients ranged from 0% to 65.8%. Therefore, the color scale was coded in equal intervals of 10.96 units (Fig. 1). In the shoulder and neck region (Fig. 1), the anterior view shows pain in the upper trapezius muscles on both sides along the shoulder line, represented by green and light green tones. The pain intensity in these areas is lower compared to the head region; however, the bilateral distribution is noteworthy. In the posterior view, the upper trapezius muscles near the base of the neck exhibit pain in green to light green tones, indicating a mild-to-moderate intensity with a bilaterally symmetrical distribution.

Fig. 1.

Pain distribution in the shoulder and neck regions of bruxist patients

Pain was most frequently localized to the right (n = 700) and left (n = 610) head-neck regions, while the intraoral region had the lowest frequency (n = 143). Box counts were summarized at the patient level using the median and interquartile range (IQR). The IQR, representing the middle 50% of the distribution, allowed the evaluation of pain spread across anatomical regions and inter-individual variability. A wider IQR was interpreted as indicating a more widespread and variable pain distribution, whereas a narrower IQR suggested a more limited and consistent localization pattern. (Table 2).

Table 2.

Quantitative distribution of pain frequencies and prevalence across anatomical regions

Anatomical Region	Total Boxes Marked (n)	% of Total Possible Boxes (n/24,000)	Number of Patients Reporting Pain (n = 200)	Interquartile Range IQR
Right Lateral Head	700	2.92%	198	12,75
Left Lateral Head	610	2.54%	192	9
Frontal Head	548	2.28%	155	14,5
Posterior Head	312	1.30%	70	4,75
Posterior Body (Shoulder/Neck)	209	0.87%	76	5
Anterior Body (Shoulder/Neck)	208	0.87%	71	5
Intraoral Region	143	0.60%	42	8

In the lateral view of the head region, there is a marked intensity of pain in the temporal, masseter, and preauricular areas with visible transitions from yellow to red. In the frontal view, both the masseter and temporal regions on each side show concentrations of green to yellow tones. Mild pain in green tones is reported in the forehead region. In the posterior view, the neck area, particularly the suboccipital muscles, shows a distribution of mild pain in light green to green tones. In the posterior view, mild pain markings were observed in the suboccipital region. Mild intraoral markings were also noted in the posterior buccal regions; however, these findings should be interpreted only as perceived pain localization and not as evidence of a specific pain mechanism (Fig. 2).

Fig. 2.

Pain distribution in the craniofacial region of bruxist patients

Discussion

The literature suggests that pain drawings along with heat map analysis come with some clear advantages compared to older, traditional pain assessment methods, mainly because they help with spatial specificity and also more objectivity. In practice, these kinds of approaches let you visually map pain intensity and its anatomical layout at the same time, so clinicians and researchers can get a fuller picture of how pain is actually patterned. Traditional pain drawings are still pretty important for recording where a person feels pain, but heat map analysis adds another layer, because it pools the pain data across a patient group, and then it becomes possible to see pain distribution patterns at the population level. It can also help reveal which anatomical regions show the greatest pain frequency and intensity, things that might not jump out when you only look at one individual’s drawings. On top of that, heat maps tend to reduce the subjective part of interpreting results, since they provide a standardized and semi quantitative type of display for how often pain occurs. Clinically, heat map outputs make it easier to spot the usual pain hotspots linked to bruxism, and this supports a more focused examination of the masticatory muscles and the cervical area. Also, this method could support treatment planning, by pointing toward regions that might respond better to targeted interventions, and it may be handy for tracking how pain distribution changes after therapeutic management [10, 11]. This study is the first to visualize the spatial distribution of pain in bruxist patients using pain drawings combined with heat-map analysis. Our findings revealed that pain in bruxism is predominantly localized to the head and neck regions, with the highest frequency in the bilateral temporal, masseter, and preauricular areas, and the lowest frequency in the intraoral region. These results are consistent with previous reports suggesting that pain complaints in individuals with bruxism may coexist with symptoms in craniofacial and cervical region [19].

In our study, the intraoral region was the least frequently marked area (n = 143, 0.60%), suggesting that intraoral discomfort was less prominent than extraoral pain complaints in this sample. Although bruxism involves repetitive tooth contact, the resulting pain is often a manifestation of muscle fatigue and myofascial trigger points in the masseter, temporalis, and medial pterygoid muscles. The extraoral distribution observed in this study should therefore be interpreted as perceived pain localization rather than as direct evidence of a specific muscular pain source. Intraoral tissues may also exhibit a higher tolerance to mechanical loading and are less likely to be perceived as a primary pain source unless acute mucosal injury or inflammation is present. Mild intraoral markings in the posterior buccal regions may reflect perceived discomfort in these areas; however, the present study design does not allow identification of the underlying pain source. The predominance of extraoral markings may indicate that these regions were more noticeable or clinically relevant to patients when completing the pain drawings. Similar pain distribution patterns with minimal intraoral involvement have been reported in pain-drawing studies of temporomandibular disorders, despite significant masticatory muscle involvement [11].

Considering that NRS scores are evaluated on an 11-point scale ranging from 0 to 10, the mean score of 3.16 ± 2.27 in this study indicates that patients with probable bruxism generally reported low-to-moderate pain intensity. This level of pain generally does not completely restrict daily activities but can reduce comfort and quality of life [20]. Particularly in conditions such as bruxism, which involve chronic and repetitive muscle activity, this type of low-to-moderate pain may lead to cumulative musculoskeletal loading over time.

The frequent head–neck markings observed in this study may suggest possible involvement of craniofacial and cervical regions; however, they do not demonstrate that probable bruxism directly causes sustained muscle contraction, overload, or myofascial pain. Comparable widespread patterns have been documented in TMD populations, where pain drawings frequently highlight not only the jaw area but also cervical, shoulder, and upper back regions [11]. This may indicate central sensitization or secondary involvement of adjacent muscle groups due to altered head posture and chronic parafunctional loading [21].

Our finding that female participants reported significantly higher pain severity is consistent with evidence showing sex-related differences in pain processing and modulation. Hormonal fluctuations, psychosocial stress, and lower mechanical pain thresholds have been proposed as possible mediators [22]. In the present study, self-reported irregular sleep patterns were associated with higher NRS scores. However, because of the cross-sectional design, this finding should be interpreted strictly as an association rather than evidence of a causal relationship. In line with this, previous studies [23] have reported relationships between sleep disturbances, bruxism, and pain perception; nevertheless, the exact direction and underlying mechanisms of these associations require further investigation in longitudinal studies.

Our findings suggest that the localization of pain in bruxist individuals may be a cumulative result of posture related musculoskeletal loading, and central sensitization mechanisms, kind of. This backs up the idea that bruxism is not just an isolated tooth clenching activity but rather an integrated part of the cranioservical–mandibular system, which could be mediated by trigeminocervical convergence. In line with that view, the literature has reported that neck dysfunction often occurs together with temporomandibular disorder (TMD) symptoms and that this link can be interpreted through shared neuromuscular and neuroanatomical mechanisms between the cervical muscles, and the masticatory muscles [24–26]. Furthermore, for every inch of forward head posture from the neutral position, the load on the cervical spine increases by approximately 10–12 pounds (4.5–5.5 kg) [27]. This biomechanical load may lead to chronic tension in the suboccipital, sternocleidomastoid (SCM), and upper trapezius muscles [28], thereby generating abnormal stresses on the TMJ and the masticatory muscles. The pain distribution patterns observed in our heat maps can be explained by the neuroanatomical mechanism of the trigeminocervical complex, where nociceptive afferents from the trigeminal nerve converge with the upper cervical spinal nerves within the spinal trigeminal nucleus. However, the present findings do not directly demonstrate trigeminocervical convergence, muscle hyperactivity, or bidirectional pain transmission; therefore, these mechanisms should be considered hypothetical and require confirmation in future studies [29].

Limitations

This study has several limitations that should be considered when interpreting the findings. First, bruxism status was classified as probable based on self-reports and clinical examinations. Because instrumental assessments such as polysomnography or electromyography were not performed, a diagnosis of definite bruxism could not be established. Similarly, pain intensity, localization, and sleep patterns were assessed using patient-reported, single-item, or subjective measures (NRS, pain drawings, and a self-reported sleep question) rather than physiological measurements or validated sleep questionnaires. Consequently, these variables reflect the participants’ subjective perceptions and self-reported behaviors rather than objective physiological data or comprehensive sleep profiles.

Additionally, the recruitment strategy may have introduced selection and referral bias. The study sample did not represent individuals from the general population with probable bruxism; rather, participants consisted of individuals with probable bruxism who had already sought clinical care due to pain-related complaints. Therefore, the observed pain characteristics and associations may be influenced by the presence of clinically significant pain that motivated healthcare-seeking behavior, and the findings may not be fully generalizable to asymptomatic individuals with probable bruxism or community-based populations. Future studies recruiting participants through population-based sampling approaches or including individuals with probable bruxism regardless of pain status would help clarify whether the observed patterns are specific to symptomatic patients or reflect broader characteristics of probable bruxism.

Furthermore, the absence of a healthy control group limits the ability to determine whether the observed pain distribution patterns, pain intensity, and sex-related differences are specific to probable bruxism or merely reflect baseline musculoskeletal pain and general pain perception differences in the population. Finally, the cross-sectional design of the study precludes causal inferences or the evaluation of temporal relationships between probable bruxism, pain development, and modifying factors such as sleep patterns or gender.

To address these limitations, future longitudinal studies incorporating objective diagnostic tools (e.g., actigraphy, polysomnography, or electromyography), complementary clinical assessments such as pressure pain threshold testing, population-based recruitment strategies, and well-defined control groups are warranted.

Conclusions

In people with probable bruxism, self reported pain is usually mostly concentrated in the head neck area. It seems like, when you look at the group, being female and having self reported irregular sleep habits tied in with a higher perceived pain intensity. This work sort of gives a more fine grained picture of how patients describe pain location, using standardized digital pain mapping and it could help clinical assessment, by pointing out the usual anatomical pain patterns seen in probable bruxism. For what comes next, more future research is needed, especially studies that include instrumental bruxism assessment, validated sleep measures, solid control groups, and also additional checks for pain sensitivity as well as masticatory muscle activity, because that would make the findings more trustworthy and more generalizable, in a broader sense.

Authors' contributions

MT: concept and study design, statistical analysis, preparation of the figures, wrote the main manuscript text. ME: data curation, preparation of the figures, wrote the main manuscript text. All authors reviewed and approved the final version of the manuscript.

Funding

No external funding was obtained for this study.

Data availability

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was conducted in alignment with the principles outlined in the Declaration of Helsinki, incorporating all required protocols and amendments. Ethical compliance of the research was reviewed and approved by the Ethics Committee of the Faculty of Dentistry, Necmettin Erbakan University (Approval No: 2024/370).

Informed consent was obtained from all participants prior to their inclusion in the study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.