|Year : 2020 | Volume
| Issue : 2 | Page : 173-181
Maximum mouth opening and its association with gender, age, height, weight, body mass index, and systemic disease in adult Saudi population: A cross-sectional study
Zuhair H Moosa1, Abdulkarim G Slihem2, Abdullah A Junaidallah2, Abdulmalik A Alshathri2, Abdulrahman K Abo Al Samh2, Moustafa M Kandil2
1 Oral and Maxillofacial Surgery Department, College of Dentistry, Riyadh Elm University, Riyadh, Saudi Arabia
2 College of Dentistry, Riyadh Elm University, Riyadh, Saudi Arabia
|Date of Submission||25-Sep-2019|
|Date of Acceptance||12-Nov-2019|
|Date of Web Publication||28-Mar-2020|
Dr. Zuhair H Moosa
Oral and Maxillofacial Surgery Department, College of Dentistry, Riyadh Elm University, Olaya, Riyadh.
Source of Support: None, Conflict of Interest: None
Aim: To analyse determine the maximum mouth opening (MMO) among adult patients seeking dental care in university dental clinics in Riyadh city, Saudi Arabia, and to find out the factors (gender, age, height, weight, body mass index [BMI]) and/or systemic disease associated with the MMO among the studied sample. Materials and Methods: This cross-sectional study was conducted on 391 adult patients aged over 21 years for a period of 2 months from February 2018 to April 2018. The MMO was measured by requesting the study participants to open his/her mouth maximally and then measuring inter-incisal length between upper and lower anterior teeth using Willis Bite Gauge. Descriptive statistics of frequency distribution, percentages, mean, and standard deviation values of MMO were calculated. Regression analysis was performed to identify predictor variables associated with the MMO. Results: Mean MMO and standard deviation of the sample was 46.15 mm and 8.49 mm. Male study subjects showed higher MMO of 48.35 ± 7.07 mm as compared with the female subjects’ MMO of 36.39 ± 7.35 mm. The MMO reduced with increasing age of the study subjects, and it showed significant differences across different age groups, gender, educational level, and health status. Weight and BMI showed significant differences with MMO. Presence of upper right and left third molars was also significantly related to MMO. Conclusion: In this study, reported MMO among the sample is lower than that reported in European and African population. Furthermore, MMO is affected by age, gender, educational level, weight, BMI, and presence of upper third molars in the sample.
Keywords: Age, Body Mass Index, Gender, Height, Maximum Mouth Opening, Systemic Disease
|How to cite this article:|
Moosa ZH, Slihem AG, Junaidallah AA, Alshathri AA, Abo Al Samh AK, Kandil MM. Maximum mouth opening and its association with gender, age, height, weight, body mass index, and systemic disease in adult Saudi population: A cross-sectional study. J Int Oral Health 2020;12:173-81
|How to cite this URL:|
Moosa ZH, Slihem AG, Junaidallah AA, Alshathri AA, Abo Al Samh AK, Kandil MM. Maximum mouth opening and its association with gender, age, height, weight, body mass index, and systemic disease in adult Saudi population: A cross-sectional study. J Int Oral Health [serial online] 2020 [cited 2020 May 28];12:173-81. Available from: http://www.jioh.org/text.asp?2020/12/2/173/281493
| Introduction|| |
Maximum mouth opening (MMO) is defined as “the greatest distance between the incisal edge of the maxillary central incisors to the incisal edge of the mandibular central incisors at the midline when the mouth is open as wide as possible.” Mouth opening can be restricted by various diseases and factors such as trauma, inflammation, temporomandibular joint disorders, neurological disorders, hyperplasia of the coronoid process, rheumatoid arthritis, side effects of drugs, tumors,,, and consequences of head and neck cancer radiotherapy.
Worldwide studies investigated MMO among different populations, and the range variation in MMO was reported. An American study conducted among the patients aged 4–14 years reported MMO of 43.99 mm. However, French and Irish studies have been reported an increase in the average of MMO between men and women. These studies have concluded a direct relationship between mouth opening and age, as well as the diversity between men and women in MMO.
Study conducted by Sawair et al. measured the Active (Voluntary) Maximum Mouth Opening (AMMO), thus associating the AMMO with a number of variables including age, gender, weight, height, body mass index (BMI), and a history of temporomandibular joint (TMJ) problems among the Jordanian population. The mean finding of AMMO accounted for 42.9 ± 5.7 mm, ranging from 29 mm to 71 mm. The range of AMMO among men and women was 33–71 mm and 29–60 mm, respectively. A higher range of AMMO was noted in the male sample as compared to female samples. Positive significant correlations between height and AMMO, thus weight and AMMO, were assessed; however, both were considered to be weak. Where third molar teeth were present, a wider range of AMMO was found, but neither BMI nor decayed, missing or filled teeth (DMFT) index revealed correlations with AMMO.
In Saudi Arabia, two studies have been conducted to measure the MMO. El- Abdin et al. conducted a study of 1158 patients between the ages of 5 and 70 years old measuring the MMO, and they found that the average MMO was 46.12 mm. The second study was made by Al-Dlaigan, who had enquired the MMO in Saudi adolescents between the ages of 12 and 16 years old including both genders. The mean MMO for men was 43.5 ± 4.23 mm, as for women the MMO reported was 35.5 ± 4.4 mm. This study reported that MMO in men is remarkably higher than in women of all age groups.,
Measuring the MMO is important to assess the function of TMJ; thus, it is also helpful in diagnosis of TMJ limitations and disorders. Reduction in mouth opening may cause masticatory and social problems; it can also be an obstacle in the dentist’s office. Some studies examined the possible relationships between MMO and age, gender, height, weight, or different facial types., In spite of this, there is scanty of published studies in the Kingdom of Saudi Arabia that focuses on this specific association between MMO and factors associated with it.
This study aimed to determine the MMO among adult patients seeking dental care in private university dental clinics in Riyadh city, Saudi Arabia, and to find out the factors (gender, age, height, weight, and BMI) and/or systemic disease associated with the MMO among the studied sample.
| Materials and Methods|| |
Study design and setting
This cross-sectional study was conducted for a period of 2 months from February 2018 to April 2018. Study data were collected from the Munisiya campus of the College of Dentistry, Riyadh Elm University, Riyadh, Saudi Arabia.
Patients seeking dental care within the Riyadh Elm University dental clinics were recruited in the study based on the inclusion criteria, that is, study participants should be adults aged above ≥21 years and undergoing dental care. On the contrary, patient’s unwilling to provide consent, having trismus, missing anterior teeth, craniofacial deformities, having history of facial traumas, presence of an ongoing infection, and systemic diseases that involve the TMJ (e.g., Rheumatoid arthritis) were all excluded from the study.
Sample size and technique
The estimated minimum number of subjects deemed to be included in the study is 385 adults with an equal gender distribution. However, to increase the power of study total samples of 391 subjects were recruited in the study. The sample size was determined using openepi.com for sample size calculation. A convenient sampling technique was used to select the study subjects.
Measurement of variables
Demographic data of age, gender, nationality, educational level, and presence of systemic diseases of the study participants were recorded by interviewing to the study participants. Height (cm), weight (kg), and BMI were recorded and categorized based on the International Classification of adult underweight, overweight, and obesity [Table 1].
|Table 1: The International Classification of adult underweight, overweight and obesity according to BMI|
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Study participants were then subjected to the intraoral examination to record oral health status and the third molar status (erupted, impacted, or missing). All the oral examination was performed under the artificial light of dental chair, using flat surface mouth mirror, gauze, and compressed air, whereas patient seated on dental chair. Clinical presence or absence of third molars were assessed without the radiographs.
Measurement of maximum mouth opening
The MMO was measured by requesting the study participants to open his/her mouth maximally and then measuring the inter-incisal length between upper and lower anterior teeth by using Willis Bite Gauge. All the measurements were performed by the trained and calibrated dental intern. All the data were recorded in a special form prepared for the recording purposes.
Statistical analysis was undertaken by using the Statistical Package for Social Sciences software, version 22.0. Descriptive statistics of frequency distributions, percentages, mean, and standard deviations were calculated for the variables. Chi-squared test was applied to the categorical data, whereas independent t-test was used to compare the means of two groups. Regression analysis was applied for the determination of the best predictors of MMO. The significance level was set at P < 0.05.
| Results|| |
A total of 391 subjects participated in this study (men = 319 and women = 72). Majority of them were in the age group of 21–30 years having low educational levels. High numbers of subjects were healthy. MMO showed a significant difference across different age groups (P = 0.004) with a greater number of participants having highest mouth opening of 61–69 mm observed in 21–30 years age group. Similarly, gender also showed significant differences in MMO (P = 0.000) with a greater number of male subjects having MMO of 46–50 mm, whereas a large number of females showed MMO of 31–35 mm. When MMO was compared across different educational levels of the study participants, a significant difference was observed (P = 0.016). The MMO also showed significant differences across health status of the study subjects (P = 0.012) as displayed in [Table 2].
|Table 2: Relationship between maximum mouth opening (mm) and demographic variables|
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Male study participants showed a mean MMO of 48.35 ± 7.07 mm and female participants showed 36.39 ± 8.49 mm. An overall mean MMO of 46.15 ± 8.49 mm was observed among all the study participants [Table 3].
When mean MMO is compared across various systemic diseases, a statistically significant difference was observed (P = 0.000), as shown in [Table 4].
An overall height of 170.15 ± 8.93cm, weight of 80.23 ± 19.43kg, and BMI of 27.72 ± 6.51kg/m2 were reported among study participants. Female subjects showed higher mean height (171.13 ± 7.72 vs. 169.93 ± 9.18cm), weight (84.29 ± 18.83 vs. 79.31 ± 19.48kg), and BMI (29.32 ± 6.37 vs. 27.47 ± 6.53) kg/m2 values as compared to the male subjects as shown in [Table 5].
|Table 5: Distribution of height, weight, and BMI across different gender|
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Various weight categories of the study participants showed statistically significant differences across MMO groups (P = 0.044). Similarly, BMI of the study participants showed significant differences with regard to MMO (P = 0.029). However, height of the study participants did not show any significant differences across MMO categories (P = 0.636), as shown in [Table 6].
|Table 6: Relationship between maximum mouth opening (mm) height, weight, and BMI|
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Lower right third molars 48 were the most commonly (24%) impacted tooth followed by 28 (23%), 38 (23%), and 18 (22%). Percentage of erupted third molars were 18 (38%), 28 (38%), 48 (37%), and 38 (35%). Similarly, percentage of missing third molars were 38 (41%), 18 (39%), 28 (39%), and 48 (38%), respectively, as shown in [Table 7].
|Table 7: Overall distribution of impacted, erupted, and missing third molars|
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Male study subjects showed higher rate of impacted third molars compared to the female subjects. On the contrary, all the missing third molars were higher in female participants as compared to the male study participants. A higher percentage of erupted 18, 28, and 38 were observed among males, whereas erupted 48 were commonly found among female participants [Table 8].
|Table 8: Gender wise distribution of impacted, erupted, and missing third molars|
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Mean MMO is significantly higher (47.79 ± 8.39 mm) in the presence of upper right third molars as compared to the absence of upper right third molars (45.28 ± 8.61 mm) (P = 0.005). Similarly, participants with the presence of upper left third molar showed significantly higher MMO (47.46 ± 9.13 mm) as compared to the absence of this molar (45.48 ± 8.19 mm) (P = 0.027). However, presence of lower right third molar and lower left third molars did not show any significant difference with regard to the MMO, as shown in [Table 9].
Categories of MMO did not show any significant relationship with the impacted, erupted, and missing third molars, as shown in [Table 10].
When used as continuous variables and the effects of other factors were controlled age, weight and height were found to be insignificant independent predictors of MMO in women and men (P > 0.05), as shown in [Table 11].
|Table 11: Insignificant independent predictors of active maximum mouth opening in multivariate analysis in women and men|
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| Discussion|| |
In this study, we measured MMO of the patients attending university dental clinics. It was difficult to ensure that the recorded mouth opening truly represents the maximum opening of the mouth after single measurement. Moreover, studied sample comes from the patients seeking care from dental clinics of teaching university. The sample size was small and selected from one center of Riyadh city because of the constraints of time and funds. Hence, wider generalizations of the study findings are unlikely and further, large representative sample from various parts of the Saudi Arabia are required to con- firm the results of this study.
The MMO in this study referred to the inter-incisal distance achieved during MMO. This measurement has only clinical and social significance. However, inclusion of overbite to the measurement would be a more precise reflection of the movement made by the mandible.
In this study, MMO is found to be higher in men compared to the women, and this finding is in line with the previously reported studies that have reported higher MMO among male subjects.[14-16], One of the reasons for such finding is the mandibular length differences between genders coupled with the values of the spatial parameters that are significantly higher in men compared to the women., It has been reported that length of the mandible from the hinge axis to lower incisors is positively correlated with MMO as it permits more rotation of the hinge joint. However, Ferrario et al. did not report gender differences in MMO. On the contrary, Pullinger et al. showed that the women had higher MMO after correcting stature and body mass.,
The mean MMO for the study participants was found to be 48.35 ± 7.07 mm higher than that of reported by Al-Dlaigan et al., in which they reported MMO of 43.5 ± 4.23 mm (range 29–59 mm). This lower mean MMO was because of the study participants being adolescents aged between 12 and 16 years. However, in our study we included subjects aged 21 years and above as study participants in whom mandibular growth was comparatively more than the adolescent grouped. This reported mean MMO is higher than that reported among Jordanian adults, wherein MMO of 42.9 ± 5.7 mm was reported. On the contrary, European studies have reported higher MMO compared to our study in which MMO surpassed more than 51 mm., The MMO was found to be significantly higher in African patients in which average MMO for men were 56.1 ± 4.8 mm, and for women 52.3 ± 4.3 mm. The variations could be because of the differences in sample and or measurement methods. Moreover, variations in body height among different population groups could also explain this difference. Hence, one can speculate that Japanese subjects have relatively small MMO compared to the Caucasians. Variation in facial morphology also contributes for MMO of an individual. Therefore, variations in facial morphology amongst different nationalities could be considered as one of the factors concerned with the MMO. It has been found that 25%–40% of inter-individual differences of mouth opening could be because of the variations in facial morphology with the angle between ramus of the mandible and posterior cranial base with ramus playing an important role.,
Our study showed a reduction in MMO with age in adults, the high number of study participants with 61–69 mm of MMO of was seen in the age group of 21–30 years, whereas subjects with lowest mouth opening 19–25 mm was observed with 41–50 years old. MMO of 61–69 mm was observed in male subjects, whereas females showed MMO of 46–50 mm. This finding is in line with the previously reported literature.,, One of the possibilities for the reduced MMO during old age could be attributed to the degenerative joint disease in the temporomandibular joint. It has been shown that progression of severity of bony changes in the condylar head and the mandibular fossa increase with aging process. Hence, TMJ osteoarthritis is commonly seen among older age group patients compared to the younger age groups. Although in regression analysis age was an independent predictor of MMO in both men and women in this study, its effect is almost similar without any significant difference. It is commonly observed that young women usually feel embarrassing to open their mouth to the maximum. Another probable cause that affects the MMO is the presence of systemic diseases in which muscular apparatus and bone may get affected influencing MMO. Aging process coupled with underlying medical conditions can significantly reduce the MMO. Hence, in our study numbers of subjects with MMO of 61–69 mm were very less.
In this study, a significant difference was observed with weight and MMO. Study participants weighing 61–80kg. It showed mouth opening of 61–69 mm. This finding is in line with the reported study by Sawair et al. Previous literature on relationship between body weight and MMO is inconsistent. Some studies have pointed out association between body size and MMO,, whereas other studies have reported no such relation between body weight and MMO.,
High number of study participants in the height range of 166–170cm showed mouth opening of 61–69 mm. However, cross-tabulation between various height categories and MMO did not show any significant relationship which is similar to the finding reported by Ingervall. Same study reported positive correlation of height and weight of children with the MMO.,, In this study, MMO revealed significant differences across different BMI categories. Subjects with normal range of BMI showed higher MMO. This finding was contradictory to the study reported by Sawair et al., in which no positive correlation between BMI and temporomandibular joint disorders affecting MMO was observed.
Restricted mouth opening is commonly associated with TMJ dysfunction syndrome. General symptoms associated with TMJ dysfunction include headache, jaw pain, and mobility issues of opening and closing mouth. Also, joint sounds during movement of the jaws because of mechanical disturbance within the joint. Numerous studies reported TMJ sounds as most common sign of temporomandibular disorders. In this study, we excluded the subjects with any of the TMJ disorders in order to obtain MMO among subjects with disease free TMJ.
Several studies have assessed the relationship between MMO and dental status of the patients., In this study, intraoral examination was performed to assess the status of the third molars, and its influence on MMO. It was obvious that presence of lower third molars is not significantly associated with the MMO. However, presence of upper third molars is significantly associated with the increased MMO. This finding is in line with the study reported by Sawair et al. Fukui et al. in their study reported the correlation between MMO and mandibular length and mandibular angle. Based on this fact, it can be argued that clinically presented third molars have longer mandibular length accommodating the mesiodistal dimension of third molar teeth with increased MMO.
In this study, impacted, erupted, and missing third molars did not show any significant associations with various categories of MMO. This finding is in contradiction with the study reported by Sawair et al., in which weak significant negative correlation between MMO and the number of missing teeth was observed. Researchers reasoned that missing mandibular posterior teeth may hasten the process of degenerative joint diseases leading to reduction in mouth opening.,
Our study has encountered some limitations, which included that the data collection had been done only in one setting which might not be an accurate representation of all Saudi population. In addition, the limitation of number of participants that have systemic diseases, thus there may be an inaccurate significance between MMO and systemic diseases. Consequently, further studies with larger number of participants may shed some light regarding this possible confounding element.
Our study is considered the first study giving a baseline regarding the range of MMO in study participants Saudi Arabia. Furthermore, describing the correlation of MMO with deferent variables. This study can serve multiple specialities in dentistry, by knowing the normal range of opining in Saudi population, to predicting the MMO of patient based on the significant variables in this study.
Within the limitations of the study, it can be concluded that our findings may be considered as the basic reference values of MMO in the assessment and follow-up of adult patients complaining limited mouth opening. The recorded MMO among the study sample is comparatively smaller than that of reported in Europe and African population. Of the factors tested age, gender, education and health status, weight, BMI, and presence of lower third molars have significant influence on MMO. Further studies on measurement of the MMO in general population from various provinces with large sample are needed to confirm the present study findings.
Ethical policy and institutional review board statement
The study proposal was submitted to the research center of Riyadh Elm University and formal registration number was obtained (Protocol no. FRP/2018/83). Furthermore, Institutional Review Board of Riyadh Elm University gave ethical clearance for the study (Protocol no. RC/IRB/2018/808). Purpose of the study explained to the patients and informed consent to participate in the study was obtained from the patients.
We would like to thank Dr. Sadeen Alshiha for her contribution in the data collection.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11]