Evaluation of the prevalence Temporomandibular Disorders (TMD) in completely Edentulous Syrian Patients Before and after the Delivery of New Complete Dentures: A Clinical Study

Introduction

Temporomandibular disorders (TMD) are among the most prevalent functional impairments affecting the masticatory system. They primarily involve the temporomandibular joint (TMJ), the masticatory muscles, and surrounding structures. Clinically, TMD manifests with symptoms such as joint or muscular pain, joint sounds (clicking or crepitus), mandibular deviation, or limited mandibular movement. In some cases, it may also present as headaches or referred pain in the ears or neck.¹ These disorders have a considerable impact on patients’ quality of life and oral function.²

TMD is considered a multifactorial condition, with contributing factors including anatomical and functional imbalances, psychological stress, occlusal discrepancies, and muscular hyperactivity.^3,4 Complete edentulism is one of the major risk factors for TMD, due to the loss of natural occlusal support and vertical dimension, which alters mandibular posture and increases uneven loading on the joint.⁵

Several studies have shown that the use of properly fabricated and stable complete dentures can reduce TMD symptoms by restoring vertical dimension, stabilizing occlusion, and alleviating muscular strain.^6,7 However, most of these studies were conducted in non-Arab populations, and the unique demographic and psychosocial characteristics of Syrian patients may limit the generalizability of their findings.⁸

Temporomandibular disorders (TMD) represent a significant clinical challenge in the rehabilitation of completely edentulous patients due to their multifactorial etiology, which involves anatomical, psychological, and functional factors. Accurate assessment of TMD symptoms and their relationship with relevant clinical variables is essential for understanding patient-specific responses to prosthetic treatment.^4,9

Therefore, this study aims to assess the prevalence of TMD symptoms before and after the delivery of complete removable dentures in a sample of completely edentulous Syrian patients. It also focuses on the distribution and severity of symptoms and their relationship with variables such as sex and duration of edentulism.

Materials and methods

This descriptive clinical study was conducted at the Department of Removable Prosthodontics, Faculty of Dentistry, Damascus University, between 2021 and 2024. The research was part of a master’s thesis in prosthodontics and aimed to evaluate changes in temporomandibular disorder (TMD) symptoms before and after the insertion of complete removable dentures, using standardized clinical diagnostic protocols.

Ethical considerations: This study was approved by the Research Ethics Committee at the Faculty of Dentistry, Damascus University. Approval was obtained prior to data collection and patient recruitment. The ethical approval was granted on September 2021 under the reference number 2264-2021. All procedures were conducted in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments.

This study was completed according to the CONSORT guidelines and is attached in the link (https://doi.org/10.17605/OSF.IO/EB7J4). Consort flow chart of patients (https://doi.org/10.17605/OSF.IO/EB7J4).

The study was prospectively registered in the ISRCTN registry under the identifier ISRCTN11645832 (https://doi.org/10.1186/ISRCTN11645832).

Informed consent: All participants were informed of the nature, objectives, and procedures of the study and provided written informed consent before enrollment. The consent process was supervised by a faculty member, and participants were assured of the confidentiality of their responses and the right to withdraw at any time.

The sample consisted of 103 patients (both male and female) who met the following inclusion criteria: Complete edentulism in both the maxillary and mandibular arches for at least six months, Absence of severe neuromuscular or psychological disorders, or congenital jaw deformities, Willingness and ability to provide informed consent and attend follow-up visits.

Patients with a history of TMJ surgery, recent trauma, or noncompliance with follow-up were excluded. The sample included a diverse distribution in terms of sex and duration of edentulism, to allow for subgroup analysis.

Each patient underwent two clinical examinations: one before denture insertion and another Six months after using the new dentures.

Initially, a comprehensive clinical examination of the temporomandibular joint (TMJ), masticatory muscles, and cervical muscles was performed to identify signs and symptoms of dysfunction. The diagnostic criteria adopted in this study were the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Due to the variety and complexity of TMD and the lack of universally accepted diagnostic standards, a scientifically-based clinical protocol was developed by Dworkin and LeResche which includes Axis I (Physical Axis): a clinical examination of muscles and joints.¹⁰

Results

The study included a sample of 103 patients from the Department of Removable Prosthodontics at the Faculty of Dentistry, Damascus University. The sample consisted of 77 males (74.8%) and 26 females (25.2%) ( Table 1).

Regarding age distribution, the majority of patients were in the 51–70 age group (74.8%), followed by the 71–90 group (13.6%), and then the 30–50 group (11.7%) ( Table 2).

As for the duration of edentulism, 66 patients (64.1%) had been edentulous for less than 5 years, 29 patients (28.2%) for 6–10 years, and only 8 patients (7.8%) for more than 10 years ( Table 3).

Regarding TMJ sounds, they were observed in 25 patients (24.3%) at the time of prosthesis delivery, decreasing to 4 patients (3.9%) after six months, indicating gradual improvement.

Limitation of mandibular movement was initially present in 23 patients (22.3%), but this number dropped to 3 patients (2.9%) after six months. Meanwhile, 100 patients (97.1%) demonstrated complete restoration of normal jaw function.

Regarding mandibular movement pattern during mouth opening, 90 patients (87.4%) initially showed straight movement while deviation was observed in 13 patients (12.6%), After six months, straight opening was seen in 99 patients (96.1%), and deviation persisted in only 4 patients (3.9%), with the disappearance of other abnormal patterns.

Regarding muscular pain, each muscle was assessed individually:

Masseter muscle: Mild to moderate pain was reported by 13.6% of patients at the time of prosthesis delivery, which dropped to 2.9% after six months.

Temporalis muscle: Initially, 6.8% of patients reported mild to severe pain; which decreased to just 1% after six months.

Medial pterygoid muscle: Pain was present in 10.6% of patients initially and declined to 2.9% after six months.

Lateral pterygoid muscle: The percentage decreased from 6.8% to 1.9%.

Cervical muscles: Mild pain was reported in 8.7% of patients at baseline, and in 7.8% after six months, indicating relative stability with slight improvement.

As for TMJ pain, it was recorded in 7 patients (6.8%) at the time of prosthesis delivery and decreased to only 1 patient (0.97%) after six months ( Table 4).

The most prevalent TMD symptom was TMJ sounds (24.3%), followed by limitation in mouth opening (22.4%), lateral pterygoid muscle pain (20.4%), masseter muscle pain (13.6%), temporalis muscle pain (6.8%), cervical muscle pain (8.7%), and TMJ pain (6.8%) medial pterygoid muscle pain (1.9%).

Table 5 presents the relative distribution of patients based on the number of temporomandibular disorder (TMD) symptoms they exhibited. The data is categorized by the count of concurrent disorders, ranging from 0 (no symptoms) to 7 (maximum recorded symptoms). The majority of patients (64.1%) reported no TMD symptoms, while progressively fewer patients presented with increasing numbers of disorders. A small subset (1%) reported all seven assessed symptoms ( Table 5).

A clear relationship was observed between age group and TMD prevalence, with the highest percentage of TMD symptoms occurring in the 71–90 age group (78.6%). Statistical analysis showed a significant positive correlation between age group and the prevalence of TMD symptoms (R = 0.358, p = 0.000 < 0.05) ( Table 6).

Regarding the duration of edentulism, 64.1% of patients had been edentulous for 1–5 years, 28.2% for 6–10 years, and 7.8% for more than 10 years. The results showed that as the duration of edentulism increased, the number of TMD symptoms also increased. Specifically, 87.5% of patients who had been edentulous for more than 10 years exhibited TMD symptoms ( Table 7).

A statistically significant and strong positive correlation between the duration of edentulism and the number of TMD symptoms (R = 0.713, p = 0.000 < 0.05).

Regarding gender differences, the prevalence of TMD was higher among females, with 42.3% of women exhibiting TMD symptoms compared to 33.8% of men. However, this difference was not statistically significant (p > 0.05), although the higher percentage among females may be attributed to the sample size.

Discussion

Temporomandibular disorders (TMD) are among the most common and complex conditions that affect the temporomandibular joint (TMJ) with significant implications for patient’s quality of life. These disorders tend to increase in prevalence among completely edentulous patients, presenting additional challenges in prosthetic rehabilitation.¹

The importance of this research lies in its contribution to the clinical diagnosis of TMD and its evaluation of the therapeutic effects of complete removable prostheses in alleviating joint symptoms in this often overlooked patient population.¹⁵ The study also examined the influence of gender, duration of edentulism, providing a deeper understanding of variables associated with TMD prevalence and supporting more precise clinical decision-making.¹⁶

A dual study design was adopted, combining both descriptive cross-sectional and experimental approaches, thus enhancing the reliability and validity of the findings. The descriptive phase helped determine the baseline prevalence of temporomandibular disorders (TMD) among completely edentulous Syrian patients, while the experimental part allowed for evaluating changes after six months of inserting newly fabricated complete removable prostheses. This methodology has been supported in previous literature that emphasized the importance of combining clinical and behavioral evaluations.

Inclusion and exclusion criteria were carefully applied to reduce confounding factors. Cases that could directly affect the TMJ, such rheumatoid arthritis, trauma, anatomical deformities, or prior history of TMD treatment, were excluded in order to maintain a clinically homogeneous sample suitable for the study objectives.

The RDC/TMD protocol (Axis I) was employed for clinical diagnosis of TMD, as it is an evidence-based, standardized examination tool established by Dworkin and LeResche in 1992 for research purposes. The RDC/TMD includes two axes: Axis I for physical examination (e.g., muscle and joint assessment) and Axis II for psychosocial evaluation, which not neglected in this study, remains easy to apply and clinically informative. This study focused on functional implications of TMD rather than psychiatric diagnoses, with the objective of identifying their impact on the masticatory system.¹⁰

The clinical examination began with palpation of the TMJ and masticatory and cervical muscles to assess signs and symptoms. The RDC/TMD protocol was followed strictly, using both extra-auricular and intra-auricular palpation to detect the position of the condyle and any joint sounds during mouth opening and closing, as well as to assess for pain during these movements.

Muscle examination included extraoral palpation of each muscle group for 1–2 minutes to identify any tenderness indicative of fatigue, strain, or trauma. When palpation was not feasible (e.g., for the lateral pterygoid), functional testing was used instead.

The examination included the temporalis, masseter, medial and lateral pterygoid muscles, as well as the digastric and cervical muscles. Proper techniques were used to ensure accurate detection of pain upon pressure, and every muscle was assessed bilaterally.

Mandibular movement analysis included evaluating maximum mouth opening (normal range: 40–50 mm), lateral movements (8–12 mm), and the presence of deviation. Measurements were made using a calibrated millimeter ruler, caliper accounting for missing anterior teeth by subtracting standard incisal heights.¹²

Assessment of the prosthetic dentures was performed according to clinical parameters outlined in the Smith evaluation scale (1976), which includes vertical dimension, centric relation, support, retention, stability, balanced articulation, and esthetics.

Although MRI is considered the gold standard for diagnosing certain temporomandibular joint (TMJ) disorders, particularly those involving internal derangements or soft tissue changes such as disc displacement, this study intentionally relied on standardized clinical, specifically the RDC/TMD protocol.

This choice was based on both methodological and practical grounds. The primary goal of the study was to assess the prevalence and clinical improvement of TMD symptoms in edentulous patients before and after prosthetic rehabilitation, with a focus on functional changes rather than anatomical ones. Therefore, reliance on a reproducible and objective clinical protocol allowed for consistent assessments across all participants.

Moreover, RDC/TMD clinical evaluation—including palpation of masticatory muscles and the use of VAS for pain assessment—has been shown to be sufficient for diagnosing mild to moderate TMD in research settings. Many international studies utilize this tool without requiring imaging, unless advanced or complex joint pathology is suspected.

From a logistical perspective, MRI remains expensive, less accessible in the local healthcare setting, and not always feasible in university-based patient populations. Thus, limiting the study to clinical evaluation tools ensured uniform conditions across participants and facilitated broader applicability within the Syrian clinical context.

The results revealed a statistically significant positive correlation between age and the number of TMD symptoms. Patients aged 71–90 years exhibited the highest prevalence (78.6%) among those diagnosed with TMD. This finding supports previous research suggesting that aging contributes to degenerative changes in the joint and muscles, particularly when compounded by prolonged edentulism.^3,17 In contrast, Serman et al reported inconsistent relationships between TMD signs and age.¹⁸

Regarding the duration of edentulism, patients who had been edentulous for more than 10 years showed the highest rate of TMD symptoms (87.5%). A significant positive correlation (R = 0.713, p < 0.05) was found between the duration of edentulism and number of TMD symptoms. This can be explained by the gradual shift of the mandible from centric relation to habitual occlusion due to vertical dimension loss and the resultant strain on the TMJ and masticatory muscles.^19–21

In terms of gender, females demonstrated a higher prevalence of TMD (42.3%) compared to males (33.8%). However, no statistically significant association was found between gender and the presence of TMD (p > 0.05). Several studies, including AlZarea who have reported higher TMD rates in females, possibly due to hormonal influences such as fluctuations in estrogen, which are known to affect joint stability.^22–24

Fabricating a well-designed complete denture that restores vertical dimension and achieves correct centric relation helps in supporting muscle coordination and preventing muscular spasms.^25,26 The analysis revealed a significant improvement in TMJ-related symptoms after six months of prosthesis use. The following improvements were recorded: 84% in joint sounds, 91.3% in limited mouth opening, 78.6% in masseter muscle pain, 85.7% in temporalis muscle pain, 76.2% in lateral pterygoid pain, and 11.1% in cervical muscle pain—the latter being the lowest due to its strong relation with posture rather than the prosthesis alone.

These results affirm that properly constructed prosthetic dentures can reduce TMJ load and progressively alleviate symptoms. The dentures not only restore oral function but also contribute to overall muscular balance.

Similar findings were reported in other studies such as Kareem et al. (2017), who observed TMJ improvements within one to two months, and Goiato & Santos (2010), who recorded enhancements after six months. Abdelnabi & Swelem (2015) also demonstrated improvement based on clinical and MRI assessments after two years of denture use.^27–29

Nevertheless, Dervis (2004) found no significant change in pre-treatment TMD symptoms, possibly due to inconsistencies in patient conditions, inclusion criteria, and diagnostic standards. Some researchers suggest that when prostheses are accompanied by patient education—such as jaw exercises, massage, warm compresses, and proper nutrition—TMD symptoms may be significantly reduced and occlusal balance enhanced (Amorim et al., 2003; Humphrey et al., 2002).^14,30

Conclusion

This clinical study demonstrated a relatively high prevalence of temporomandibular disorders (TMD) among completely edentulous Syrian patients, particularly in older individuals and those with longer durations of edentulism. The findings confirmed that well-fabricated and stable complete removable dentures significantly reduce the severity and frequency of TMD symptoms after six months of use.

Age and duration of edentulism were identified as the most influential variables correlated with TMD prevalence, while gender differences, although present, were not statistically significant. These results highlight the importance of early prosthetic rehabilitation, accurate diagnosis using standardized clinical tools such as RDC/TMD, and individualized treatment planning that considers the patient’s demographic and functional profile.

Incorporating TMJ evaluation into routine clinical examination and prosthetic treatment planning for edentulous patients is recommended. Future research should expand the sample size, include longer follow-up periods, and integrate psychosocial factors (Axis II) to provide a more comprehensive understanding of TMD in this population.

Ethical considerations

This study was approved by the Research Ethics Committee at the Faculty of Dentistry, Damascus University. Approval was obtained prior to data collection and patient recruitment. The ethical approval was granted on September 2021 under the reference number 2264-2021. All procedures were conducted in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments.

The study was prospectively registered in the ISRCTN registry under the identifier ISRCTN11645832 (https://doi.org/10.1186/ISRCTN11645832).

Informed consent

All participants were informed of the nature, objectives, and procedures of the study and provided written informed consent before enrollment. The consent process was supervised by a faculty member, and participants were assured of the confidentiality of their responses and the right to withdraw at any time.