CLINICAL STUDY
Does Gum Chewing Increase the Prevalence of Temporomandibular Disorders in Individuals With Gum Chewing Habits? Reza Tabrizi, DMD,* Touba Karagah, DMD,* Ehsan Aliabadi, DMD,* and Seyed Ali Hoseini, DDS‡ Purpose: The effect of habitual gum chewing on temporomandibular joint function is controversial. This study evaluated the prevalence of temporomandibular disorder (TMD) in adolescents with and without gum chewing habits and the affiliation of TMD signs with gum chewing. Subjects and Methods: This is a cross-sectional study. Subjects were studied in 2 groups. Subjects in the study group chewed gum for 30, 60, or 120 minutes in a 24-hour day. Subjects in the control group did not have a gum chewing habit. TMD signs of clicking, crepitus, and pain were documented for every subject. Age, gender, duration of gum chewing, and occlusal relationships were variable factors, and TMD signs (clicking, crepitus, and pain) were outcomes of the study. The chi-square test was used to compare TMD signs and gender in the 2 groups, and to evaluate the relationship between TMD signs and duration of gum chewing in the study group. An independent t test was applied to compare the ages of the 2 groups. Results: Two hundred subjects participated in the study and were divided into 2 groups (100 subjects per group). An evaluation of the data showed no significant differences between the 2 groups in sex, age, and occlusion. The incidence of clicking and pain was statistically higher in the study group than in the control group (P < 0.05). Analysis of the data demonstrated considerable differences in clicking and pain among subjects with various gum chewing times in the study group (P < 0.05). The incidence of pain was higher in subjects with a class II skeletal pattern than others in the study group (P < 0.001). Nevertheless, no significant difference was noticed for clicking among subjects with various occlusions (P > 0.05). Conclusion: Considering that intensive gum chewing may affect TMD signs in individuals with a gum chewing habit. It seems a longer duration of gum chewing may increase the prevalence of TMD. Individuals with a class II skeletal pattern may be affected more than others.
From the *Oral and Dental Health Care Research Center, Department of Oral and Maxillofacial Surgery, Shiraz University of Medical Sciences, Shiraz; and †Shiraz University of Medical Sciences, Shiraz, Iran Received February 2, 2014. Accepted for publication April 4, 2014. Address correspondence and reprint requests to Reza Tabrizi, DMD, CMF ward, Chamran Hospital, Chamran Street, Shiraz, Fars, Iran; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000993
1818
Key Words: Temporomandibular disorder, gum chewing, mandible, temporomandibular joint, pain, click (J Craniofac Surg 2014;25: 1818–1821)
“T
emporomandibular disorder” is a communal term utilized to describe a number of correlated disorders involving the temporomandibular joints, masticatory muscles, and occlusion with ordinary symptoms such as pain, limited movement, muscle tenderness, and intermittent joint sounds.1 Temporomandibular disorders (TMD) occur in 12% of the general population. Regardless of widespread research dating back over 5 decades, many questions on the subject of the etiology and effective treatment of this group of disorders remain unanswered.2 Since the 1970s, a multifactorial etiology for TMD has been suggested. These possible causes of contributing factors consist of structural conditions, psychological morbidity, and behavioral problems such as parafunctional habits. Currently there is extensive discussion about the role of muscle activity in the development and maintenance of TM disorders.2,3 Even though the majority of subjects with symptoms and signs from the mandibular locomotor system are not sure about the potential causes of discomfort, some will report that the act of mastication (including the chewing of gum) is a causal factor.4 Regular gum chewing is regarded as a triggering factor of masticatory pain in TMD patients, and intensive gum chewing for several hours per day has a potentially damaging effect on the masticatory muscles and temporomandibular joint (TMJ).5 The exercise-induced muscle pain that occurs during chewing appears more commonly in the muscle generating the greatest amount of cumulative electromyographic (EMG) activity,6 and prolonged chewing tasks have also been reported to stimulate both swelling and pain. For this reason, a relationship between the muscle load and the amount of pain experienced during chewing and muscular swelling has been proposed.7 Chronic muscle pain has also been identified as owing to inefficient intramuscular blood flow and reduced muscle tissue oxygen pressure.8 Tzakis found that 30 minutes of vigorous, apparently habitual, chewing of hard gum induced temporary symptoms and signs from the mandibular locomotor system, including fatigue and pain in the jaw muscles. Although a clinical sensation of jaw muscle fatigue is not a reliable and frequent clinical complaint, it is considered a remarkable indicator of mandibular dysfunction.9 The purpose of this study was to compare the prevalence of TMD in adolescent males and females with or without a gum chewing habit.
SUBJECTS AND METHODS The authors designed a cross-sectional study. The subjects were randomly selected from students and employees in Shiraz and Azad University between September 1, 2012 and May 1, 2013. The research was approved by the Ethics Committee of the Shiraz University of Medical Sciences.
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Gum Chewing Habits
TABLE 1. Comparison of Variable Factors Between 2 Groups Study Group
Control Group
P
28.97 ± 9.39 42 males, 58 females 57 cl I, 30 cl II, 13 cl III
27.63 ± 8.18 45 males, 55 females 52 cl I, 36 cl II, 12 cl III
>0.05* >0.05** >0.05**
Variable Factors Age, yr Sex Occlusion
*Independent t test. **χ2 test.
The study group consisted of subjects who had gum chewing habits for durations of 30, 60, or 120 minutes or more in a day for 2 years or more and were older than 18 years of age. Subjects were considered for the control group if they were greater than 18 years of age and did not have gum chewing habits. Subjects demonstrating systemic diseases which affect bone and joints, parafunctional habits, psychological problems such as depression, a history of trauma or mandibular fractures, previous orthodontic treatment, or extensive prosthodontic restorations were excluded from the study sample. Gum chewing habit was considered a predictive factor of the study. A gum chewing habit was defined as habitual chewing for 30, 60, or 120 minutes in a 24-hour day. A clinical examination of the masticatory muscles was performed on test subjects by 3 investigators who participated in this study and randomly visited the subjects. This examination included palpation of the muscles and the TMJ and recording of joint sounds and pain. Temporomandibular joint noises were classified based on type of the noise: (a) reciprocal click, noise made on opening and closing from central occlusion; (b) reproducible opening click, noise with every opening; (c) reproducible closing click, noise with every closing; and (d) crepitus, grating noise on opening or closing. Pain was documented based on pain felt upon palpation and jaw movement. Subjects’ occlusion was concluded in 3 classes (class I, class II, and class III). All subjects gave written informed consent to allow the examination and inclusion of their information in the study. This study focused on the clinical signs of TMD; therefore, radiographic evaluation was not included in the study. Age, gender, gum chewing habit, and occlusal relationship are variable factors, and TMD signs (clicking, crepitus, and pain) are outcomes of the study.
FIGURE 1. Comparison of click among various durations of gum chewing (click 0: without click; click 1: with click).
control group. Results did not show a significant difference related to gender between the 2 groups (P > 0.05). The mean age of subjects was 28.97 ± 9.39 years in the study group and 27.63 ± 8.18 years in the control group. Data analysis did not show any significant difference in age between the 2 groups (P > 0.05). In the study group, 57 subjects had a class I skeletal occlusion, 30 subjects had a class II skeletal pattern, and 13 subjects had a class III skeletal pattern. In the control group, 52 subjects had a class I occlusion, 36 subjects had a class II skeletal pattern, and 12 subjects had a class III skeletal pattern. Assessment of the occlusions did not show a significant difference between the 2
Statistical Analysis Statistical analyses were performed using the statistical package SPSS for PC, version 19 from IBM, USA. The chi-square test was used to compare TMD signs and gender between the 2 groups and to evaluate the relationship between TMD signs and duration of gum chewing in the study group. An independent t test was applied to compare age between the 2 groups.
RESULTS Two hundred subjects in 2 groups (study group and control group) were studied. Forty-two males and 58 females were included in the study group, and 45 males and 55 females were studied in the
TABLE 2. Comparison of the Study Outcomes Between 2 Groups Study Outcomes Click Pain
Study Group
Control Group
χ2
31 (31%) 27 (27%)
13 (13%) 11 (11%)
Does Gum Chewing Increase the Prevalence of Temporomandibular Disorders in Individuals With Gum Chewing Habits? Reza Tabrizi, DMD,* Touba Karagah, DMD,* Ehsan Aliabadi, DMD,* and Seyed Ali Hoseini, DDS‡ Purpose: The effect of habitual gum chewing on temporomandibular joint function is controversial. This study evaluated the prevalence of temporomandibular disorder (TMD) in adolescents with and without gum chewing habits and the affiliation of TMD signs with gum chewing. Subjects and Methods: This is a cross-sectional study. Subjects were studied in 2 groups. Subjects in the study group chewed gum for 30, 60, or 120 minutes in a 24-hour day. Subjects in the control group did not have a gum chewing habit. TMD signs of clicking, crepitus, and pain were documented for every subject. Age, gender, duration of gum chewing, and occlusal relationships were variable factors, and TMD signs (clicking, crepitus, and pain) were outcomes of the study. The chi-square test was used to compare TMD signs and gender in the 2 groups, and to evaluate the relationship between TMD signs and duration of gum chewing in the study group. An independent t test was applied to compare the ages of the 2 groups. Results: Two hundred subjects participated in the study and were divided into 2 groups (100 subjects per group). An evaluation of the data showed no significant differences between the 2 groups in sex, age, and occlusion. The incidence of clicking and pain was statistically higher in the study group than in the control group (P < 0.05). Analysis of the data demonstrated considerable differences in clicking and pain among subjects with various gum chewing times in the study group (P < 0.05). The incidence of pain was higher in subjects with a class II skeletal pattern than others in the study group (P < 0.001). Nevertheless, no significant difference was noticed for clicking among subjects with various occlusions (P > 0.05). Conclusion: Considering that intensive gum chewing may affect TMD signs in individuals with a gum chewing habit. It seems a longer duration of gum chewing may increase the prevalence of TMD. Individuals with a class II skeletal pattern may be affected more than others.
From the *Oral and Dental Health Care Research Center, Department of Oral and Maxillofacial Surgery, Shiraz University of Medical Sciences, Shiraz; and †Shiraz University of Medical Sciences, Shiraz, Iran Received February 2, 2014. Accepted for publication April 4, 2014. Address correspondence and reprint requests to Reza Tabrizi, DMD, CMF ward, Chamran Hospital, Chamran Street, Shiraz, Fars, Iran; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000993
1818
Key Words: Temporomandibular disorder, gum chewing, mandible, temporomandibular joint, pain, click (J Craniofac Surg 2014;25: 1818–1821)
“T
emporomandibular disorder” is a communal term utilized to describe a number of correlated disorders involving the temporomandibular joints, masticatory muscles, and occlusion with ordinary symptoms such as pain, limited movement, muscle tenderness, and intermittent joint sounds.1 Temporomandibular disorders (TMD) occur in 12% of the general population. Regardless of widespread research dating back over 5 decades, many questions on the subject of the etiology and effective treatment of this group of disorders remain unanswered.2 Since the 1970s, a multifactorial etiology for TMD has been suggested. These possible causes of contributing factors consist of structural conditions, psychological morbidity, and behavioral problems such as parafunctional habits. Currently there is extensive discussion about the role of muscle activity in the development and maintenance of TM disorders.2,3 Even though the majority of subjects with symptoms and signs from the mandibular locomotor system are not sure about the potential causes of discomfort, some will report that the act of mastication (including the chewing of gum) is a causal factor.4 Regular gum chewing is regarded as a triggering factor of masticatory pain in TMD patients, and intensive gum chewing for several hours per day has a potentially damaging effect on the masticatory muscles and temporomandibular joint (TMJ).5 The exercise-induced muscle pain that occurs during chewing appears more commonly in the muscle generating the greatest amount of cumulative electromyographic (EMG) activity,6 and prolonged chewing tasks have also been reported to stimulate both swelling and pain. For this reason, a relationship between the muscle load and the amount of pain experienced during chewing and muscular swelling has been proposed.7 Chronic muscle pain has also been identified as owing to inefficient intramuscular blood flow and reduced muscle tissue oxygen pressure.8 Tzakis found that 30 minutes of vigorous, apparently habitual, chewing of hard gum induced temporary symptoms and signs from the mandibular locomotor system, including fatigue and pain in the jaw muscles. Although a clinical sensation of jaw muscle fatigue is not a reliable and frequent clinical complaint, it is considered a remarkable indicator of mandibular dysfunction.9 The purpose of this study was to compare the prevalence of TMD in adolescent males and females with or without a gum chewing habit.
SUBJECTS AND METHODS The authors designed a cross-sectional study. The subjects were randomly selected from students and employees in Shiraz and Azad University between September 1, 2012 and May 1, 2013. The research was approved by the Ethics Committee of the Shiraz University of Medical Sciences.
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 5, September 2014
Gum Chewing Habits
TABLE 1. Comparison of Variable Factors Between 2 Groups Study Group
Control Group
P
28.97 ± 9.39 42 males, 58 females 57 cl I, 30 cl II, 13 cl III
27.63 ± 8.18 45 males, 55 females 52 cl I, 36 cl II, 12 cl III
>0.05* >0.05** >0.05**
Variable Factors Age, yr Sex Occlusion
*Independent t test. **χ2 test.
The study group consisted of subjects who had gum chewing habits for durations of 30, 60, or 120 minutes or more in a day for 2 years or more and were older than 18 years of age. Subjects were considered for the control group if they were greater than 18 years of age and did not have gum chewing habits. Subjects demonstrating systemic diseases which affect bone and joints, parafunctional habits, psychological problems such as depression, a history of trauma or mandibular fractures, previous orthodontic treatment, or extensive prosthodontic restorations were excluded from the study sample. Gum chewing habit was considered a predictive factor of the study. A gum chewing habit was defined as habitual chewing for 30, 60, or 120 minutes in a 24-hour day. A clinical examination of the masticatory muscles was performed on test subjects by 3 investigators who participated in this study and randomly visited the subjects. This examination included palpation of the muscles and the TMJ and recording of joint sounds and pain. Temporomandibular joint noises were classified based on type of the noise: (a) reciprocal click, noise made on opening and closing from central occlusion; (b) reproducible opening click, noise with every opening; (c) reproducible closing click, noise with every closing; and (d) crepitus, grating noise on opening or closing. Pain was documented based on pain felt upon palpation and jaw movement. Subjects’ occlusion was concluded in 3 classes (class I, class II, and class III). All subjects gave written informed consent to allow the examination and inclusion of their information in the study. This study focused on the clinical signs of TMD; therefore, radiographic evaluation was not included in the study. Age, gender, gum chewing habit, and occlusal relationship are variable factors, and TMD signs (clicking, crepitus, and pain) are outcomes of the study.
FIGURE 1. Comparison of click among various durations of gum chewing (click 0: without click; click 1: with click).
control group. Results did not show a significant difference related to gender between the 2 groups (P > 0.05). The mean age of subjects was 28.97 ± 9.39 years in the study group and 27.63 ± 8.18 years in the control group. Data analysis did not show any significant difference in age between the 2 groups (P > 0.05). In the study group, 57 subjects had a class I skeletal occlusion, 30 subjects had a class II skeletal pattern, and 13 subjects had a class III skeletal pattern. In the control group, 52 subjects had a class I occlusion, 36 subjects had a class II skeletal pattern, and 12 subjects had a class III skeletal pattern. Assessment of the occlusions did not show a significant difference between the 2
Statistical Analysis Statistical analyses were performed using the statistical package SPSS for PC, version 19 from IBM, USA. The chi-square test was used to compare TMD signs and gender between the 2 groups and to evaluate the relationship between TMD signs and duration of gum chewing in the study group. An independent t test was applied to compare age between the 2 groups.
RESULTS Two hundred subjects in 2 groups (study group and control group) were studied. Forty-two males and 58 females were included in the study group, and 45 males and 55 females were studied in the
TABLE 2. Comparison of the Study Outcomes Between 2 Groups Study Outcomes Click Pain
Study Group
Control Group
χ2
31 (31%) 27 (27%)
13 (13%) 11 (11%)
