Hazel Celik Guzel

Hazel Celik Guzel

*This is an algorithmically generated author record based on publicly available information.

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Hazel Celik Guzel has a total of 54 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Patient-reported oral health complications in bipolar disorder: focus on illness duration and functional impairments

    by Hazel Celik Guzel, Berdel Celik Tokay

    Aim Although oral health problems are common in bipolar disorder, functional disorders such as temporomandibular dysfunction (TMD) and oropharyngeal dysphagia (OD), and their relationship with illness duration, have not been adequately studied. This study aimed to investigate the prevalence of oral health complications, TMD, and OD in bipolar patients based on self-reports and to assess their association with illness duration. Methods In this cross-sectional study, 70 bipolar patients aged 20–60 in remission were evaluated. The Oral Health Impact Profile-14, Numeric Pain Scale, Fonseca Anamnestic Questionnaire, Jaw Functional Limitation Scale-8, and Eating Assessment Tool were administered. Results Self-reported TMD was present in 64.3% and OD in 60% of patients. Illness duration showed a strong correlation with oral health quality (r = 0.858), TMD (r = 0.838), and OD (r = 0.865) scores (P < .001). Logistic regression revealed that each additional year of illness increased the risk of TMD 4.212 times (P = .020) and OD 2.433 times (P = .005). Conclusion Illness duration in bipolar disorder is a significant risk factor for oral health complications and functional disorders (TMD/OD). Routine screening for TMD and OD alongside dental check-ups may provide clinical benefits in this population.

  • Diminished vagal tone and altered muscle biomechanics in clinically based bruxism: An exploratory study of the autonomic-myogenic relationship

    by Hazel Celik Guzel, Ozan Bahadır Turkmen, Ebru Kaya Mutlu

    Background: Bruxism is a complex condition with a multidimensional aetiology, wherein it is cross-sectionally associated with dysfunction of the autonomic nervous system (ANS); however, the relationships among ANS activity, muscle biomechanics, and pain remain unclear. Objective: This study examined links among ANS activity, masticatory biomechanics, and pain in clinically based bruxism using quantitative methods. Methods: This observational case-control study included 44 individuals with clinically based bruxism and 45 controls. Pain intensity (at rest and during chewing via Numeric Pain Scale), ANS activity (heart rate variability, heart rate, and respiratory rate via Polar H10), and masticatory muscle properties (tone, stiffness, and elasticity via MyotonPro) were measured. Results: Compared to controls, the bruxism group showed impaired sympathovagal balance (LF/HF ratio: p < .001), reduced parasympathetic activity (HF power: p = .014), and altered muscle biomechanics (increased tone and stiffness, decreased elasticity; all p < .001). Correlation analyses found that lower HF power was negatively correlated with masseter stiffness ( r = –.373, p = .043) and pain intensity (rest: r = –.387, p = .039; chewing: r = –.572, p = .018). Increased muscle tone and stiffness were positively correlated with pain intensity ( p < .05). Conclusion: This exploratory study suggests a significant relationship among ANS dysfunction (specifically reduced parasympathetic activity), impaired muscle biomechanics, and pain in clinically based bruxism. These findings may provide a conceptual basis for multidisciplinary treatment strategies targeting ANS regulation in bruxism management.

  • Validity, reliability, and preliminary reference values of the Stroop test (Çapa Form) in adolescents with mild intellectual disability

    by Aysegul Demir Sariipek, Hazel Celik Guzel, Nurettin Konar

    An intellectual disability is defined as a developmental condition characterized by significant limitations in intellectual functioning (including learning, reasoning, and problem solving) and adap...

  • Yeni Nesil Fizyoterapi: Bilim, Klinik ve Yenilik

    by Mehmet Akif Güler, Meriç Selim Şipal, Osman Söyler, Ertuğrul Deniz Köse, Bayram Can Doğan, Merve Koku, Eylem Küçük, Serkan Bakırhan, Mehmet Özkeskin, Muhammet Cihat Aslan, et al.

    Fizyoterapi ve rehabilitasyon, dijital dönüşümün etkisiyle yalnızca tedavi yöntemleri açısından değil; eğitim, araştırma ve klinik karar verme süreçleri bakımından da yeni bir döneme girmiştir. Yapay zekâ uygulamaları, telerehabilitasyon, dijital sağlık teknolojileri, yenilikçi egzersiz yaklaşımları ve kanıta dayalı uygulamalar, modern fizyoterapi anlayışının temel yapı taşları hâline gelmiştir. Yeni Nesil Fizyoterapi: Bilim, Klinik ve Yenilik, fizyoterapi ve rehabilitasyon alanındaki güncel bilimsel gelişmeleri, klinik uygulamaları ve geleceğe yön veren yenilikçi yaklaşımları bir araya getiren kapsamlı bir başvuru eseridir. Kitapta; ortopedik fizyoterapi, nörolojik rehabilitasyon, geriatrik rehabilitasyon, telerehabilitasyon, dijital ortez-protez uygulamaları, yapay zekâ destekli eğitim modelleri, egzersiz temelli rehabilitasyon, nöromodülasyon yaklaşımları ve teknolojinin rehabilitasyondaki yeri gibi güncel konular, alanında uzman akademisyenlerin katkılarıyla bilimsel kanıtlar doğrultusunda ele alınmaktadır. Lisans ve lisansüstü öğrencileri, fizyoterapistler, akademisyenler, araştırmacılar ve diğer sağlık profesyonelleri için hazırlanan bu eser; güncel literatürü klinik uygulamalarla bütünleştirerek okuyuculara güvenilir ve kapsamlı bir kaynak sunmaktadır. Bilimsel gelişimin sürekli devam ettiği günümüzde, fizyoterapi mesleğinin geleceğine yön verecek bilgi ve yenilikleri bir araya getiren bu kitap, yalnızca bugünün değil, geleceğin rehabilitasyon anlayışına da ışık tutmayı amaçlamaktadır. Yeni Nesil Fizyoterapi: Bilim, Klinik ve Yenilik, bilimin rehberliğinde gelişen, teknolojiyi etkin kullanan ve hasta merkezli bir rehabilitasyon yaklaşımını benimseyen tüm sağlık profesyonelleri için değerli bir başvuru kaynağıdır.

  • Open Access

    Smartphone addiction and temporomandibular disorders among university students: A machine learning based multiple regression analysis study

    by Hazel Çelik Güzel, Ozan Bahadir Türkmen, Ahmet Kurtoğlu, Sule Keçelioğlu, Burcin Akçay, Ebru Kaya Mutlu, Neah Albasha, Safaa Mostafa Elkholi

    Temporomandibular disorders (TMD) involve complex interactions among behavioral and musculoskeletal factors, and machine learning (ML) has increasingly been used to model these multidimensional relationships. This study aimed to investigate the relationship between smartphone addiction and TMD symptoms by evaluating the possible contributions of clinical variables such as head posture, cervical dysfunction, and masseter muscle sensitivity to this relationship and by examining the multivariate structure using ML methods. A single-blind, cross-sectional study was conducted among university students in Turkey. Participants completed several assessments: Smartphone Addiction Scale-Short Version (SAS-SV), Fonseca Anamnestic Index for TMD severity, Neck Disability Index, Numerical Rating Scale, forward head posture, and masseter muscle pressure pain threshold using algometry. Data were analyzed using Pearson correlation, logistic regression, and various ML classification algorithms (e.g., extreme gradient boosting [XGBoost], support vector machines). Shapley additive explanations analysis was applied to determine variable importance in ML models. In this study, XGBoost demonstrated the most successful performance in determining the relationships between smartphone addiction and TMD symptoms, while the support vector machines model showed the most successful performance in classifying participants. The findings suggest that this ML based approach, taking into account postural abnormalities and masseter muscle sensitivity, could contribute to the early identification of individuals at risk for TMD and the planning of targeted intervention strategies. Research findings have revealed complex relationships between SAS-SV and TMD symptoms among university students. In analyses conducted using ML algorithms, the support vector machines model stood out with the highest classification accuracy (area under the curve [AUC] = 0.94) and performance indicators. Shapley additive explanations analyses showed that smartphone usage time, masseter muscle sensitivity, and Fonseca Anamnestic Index score were the most decisive variables on SAS-SV. In TMD prediction, the highest predictive power was explained by temporomandibular joint pain. Ensemble models such as random forest and gradient boosting yielded more successful results with lower error rates and higher R 2 values compared to classical regression methods. The findings indicate that smartphone use indirectly affects TMD through postural disorders and muscle sensitivity.


  • Masseter muscle hyperactivity and pain sensitization during smartphone use: A cross-sectional study of thenar–trigeminal interaction

    by Hazel Celık Guzel, Sule Kecelıoglu, Ebru Kaya Mutlu, Mert Durukan, Tulay Satı Kırkan

    Background: While it is known that smartphone use (SU) affects the musculoskeletal system, the effect of repetitive thumb movements on the masseter muscle has not been systematically investigated. Objective: To investigate the effects of repetitive thumb movements due to SU on the masseter muscle through thenar muscle activity. Methods: The students’ pressure pain thresholds of the thenar and masseter muscles were assessed with an algometer, and bilateral masseter muscle activation was assessed with Electromyography (EMG). Students were asked to perform repetitive thumb taps with their dominant hand for 5 min using the “Fast-Tap” smartphone application. Results: This cross- sectional observational study included 105 students aged 20.96 (2.44) years. Post-SU, right thenar (p < .001), right masseter (p < .001), and left masseter (p = .040) pressure pain threshold decreased, and right masseter muscle activation was higher in terms of %MVC values (p < .001). The right and left thenar and masseter muscle pressure pain thresholds were moderately to highly correlated (p < 0.001). Additionally, the number of thumb taps was moderately correlated with right masseter muscle activation (p < 0.001) and weakly correlated with left masseter muscle activation (p = .005). Conclusion: Repetitive thumb movements due to SU may affect the masseter muscle, and the thenar-masseter relationship may lead to innovative treatment approaches in the future.

  • A Narrative Review on Factors Affecting Access to Oral Health Services in Türkiye

    by Onur Bayrakci, Duygu Kalkay, Hazel Celik Guzel

    Oral health is an essential public health problem directly affecting people’s general health and quality of life. Rates of utilisation of oral health services in Türkiye are affected by various factors such as people’s socioeconomic status, geographical location, and ease of access to the health system. Low income, inadequate education, and lack of health insurance in private sector coverage are the main barriers in accessing oral health services. Socioeconomic inequalities affect people’s utilisation rates of oral health services and regular care habits, leading to both treatment delays and higher health costs. Increasing preventive oral health awareness and addressing the relationship between access to oral health services and social and economic factors are critical for developing sustainable policies to improve individuals’ quality of life and reduce health inequalities. In recent years, Türkiye has confronted significant challenges with elevated inflation and unemployment rates. These factors have substantially constrained access to healthcare services. Presently, Türkiye ranks sixth with the highest inflation rate globally. This review aimed to analyse the access to oral health services in Türkiye and the factors affecting this access. In addition, solutions to reduce existing inequalities are presented.

  • Open Access

    Effect of Intensive Face Yoga on Facial Muscles Tonus, Stiffness, and Elasticity in Middle-Aged Women: A Pre-Experimental Clinical Trial

    by Hazel Çelik Güzel, Şule Keçelioğlu, Ahmet Kurtoğlu, Safaa M. Elkholi

    Background and Objectives: The effects of face yoga, which continues to be popular as an anti-aging technique, on facial muscles in relation to aging represent an area of interest. The aim of this study was to investigate the effect of 8 weeks of intensive face yoga on facial muscles’ tonus, stiffness, and elasticity in middle-aged women. Materials and Methods: Twelve female participants with a mean age of 49.75 ± 3.76 were included in this pre-experimental clinical trial. Face yoga was applied to the participants for 8 weeks, 2 days a week face-to-face, and 5 days a week as a home program. At the beginning and the end of 8 weeks, the tonus, stiffness, and elasticity of the participants’ facial muscles were evaluated with the Myoton®PRO device. Results: Following the face yoga program, the tonus and stiffness of the frontalis (p = 0.008, p = 0.002), corrugator supercilii (p = 0.008, p = 0.019), orbicularis oculi (p = 0.023, p = 0.034), and orbicularis oris (p = 0.007, p = 0.015) muscles decreased significantly, while the tonus and stiffness of the buccinator (p = 0.008, p = 0.002) and digastric (p = 0.008, p = 0.023) muscles increased. Elasticity values increased in all evaluated facial muscles (p = 0.045, p = 0.045, p = 0.034, p = 0.023, p = 0.028, p = 0.005, respectively). Conclusions: The results reveal that face yoga has different effects depending on the physiological structure and function of the muscles and positively affects connective tissue. Future studies should reproduce the results presented here to further our understanding of the effects of face yoga.