Journal of International Oral Health

: 2019  |  Volume : 11  |  Issue : 6  |  Page : 353--356

Normal range of maximum mouth opening in pakistani population: A cross-sectional study

Farooq A Chaudhary1, Basaruddin Ahmad2, Danial Q Butt3, Shoaib Hameed4, Ulfat Bashir5,  
1 Department of Community Dentistry, Dental College, HITEC Institute of Medical Sciences, Taxila, Punjab, Pakistan; School of Dental Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia,
2 School of Dental Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
3 Department of Oral Pathology, Dental College, HITEC Institute of Medical Sciences, Taxila, Punjab, Pakistan
4 Department of Orthodontics, Dental College, HITEC Institute of Medical Sciences, Taxila, Punjab, Pakistan
5 Department of Orthodontics, Islamic International Dental College, Riphah International University, Islamabad, Pakistan

Correspondence Address:
Dr. Farooq A Chaudhary
Department of Community Dentistry, Dental College, HITEC Institute of Medical Sciences, Taxila, Punjab, Pakistan


Aims and Objectives: Maximum mouth opening (MMO) is an important diagnostic reference for dental clinicians as a preliminary evaluation and an indicator of function of masticatory system and temporomandibular joints. This aim of this study was to describe the normal mouth opening of Pakistani population and its possible correlation with sex and age. Materials and Methods: This cross-sectional study randomly selected visitors to the Pakistan Institute of Medical Sciences, Islamabad, Pakistan. Each subject was asked to open his/her mouth as wide as possible while sitting in an upright position, then the distance between the incisal edges of upper and lower right central incisor was measured. Independent t-test and analysis of variance were used, and significant level was set at 5% in all analysis. Results: Of the 497 subjects examined, 52.3% were males and 47.7% were females with age between 15 and 65 years. The mean MMO for all subjects was 58.2mm (standard deviation = 7.92) and ranged between 35 and 71mm. Statistically, the MMO was significantly wider in the males than in females (mean difference = 10.9mm, 95% confidence interval: 9.60, 12.2, P < 0.001). The difference between sexes was also significant in all age groups except in the 56–65 years old. The mean width of MMO declines with increasing age. Conclusion: It is concluded that the mean MMO of Pakistani males is significantly higher than the Pakistani females, and it is influenced by gender and age. The mouth opening reduces with age, and the results of this study are in agreement with the different studies in different countries.

How to cite this article:
Chaudhary FA, Ahmad B, Butt DQ, Hameed S, Bashir U. Normal range of maximum mouth opening in pakistani population: A cross-sectional study.J Int Oral Health 2019;11:353-356

How to cite this URL:
Chaudhary FA, Ahmad B, Butt DQ, Hameed S, Bashir U. Normal range of maximum mouth opening in pakistani population: A cross-sectional study. J Int Oral Health [serial online] 2019 [cited 2023 Dec 1 ];11:353-356
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A number of signs of medical and dental conditions are manifested in the oral cavity, such as dental caries, leukoplakia, oral ulceration, and jaundice; hence, examination of patients with such condition requires a good access into the oral cavity. In a normal and healthy individual, opening the mouth is not associated with any pain or discomfort. However, there are conditions where the width of mouth opening becomes restricted, also known as trismus, which can be the result of pathological changes such as maxillofacial trauma, dental, salivary glands and tonsil infections, temporomandibular joints disorders, or tumors.[1] It may also be a temporary adverse effect of postdental or tonsil removal surgery or a permanent complication such as the skin and muscle contracture because of scarring in patients who had orofacial burn injury or radiotherapy.[2] A limited opening will limit the access into the oral cavity, thus preventing a good intraoral assessment, and in dentistry particularly, making the treatment procedure of dental diseases more difficult.[3]

In a clinical situation, where a patient is presented with trismus and the normal maximum mouth opening (MMO) is not known, the width of mouth opening to be achieved in an intervention would not be clear; hence, the success of it becomes obscure. Because of this, it is beneficial to have a reference value for a normal mouth opening of a population. The MMO ranges from 42 to 60mm[4],[5],[6],[7] and varies between ethnicity, age, and gender [Table 1]; therefore, a reference for MMO is needed for every population. There is currently a report on the MMO of Pakistanis, but it has a limited inference to the original population because the sample only included students in their early twenties who were studying abroad.[7] Hence, the objective of this study was to describe the normal MMO in Pakistani population at different age range and by sex.{Table 1}

 Materials and Methods

Participants of this cross-sectional study were recruited at the Pakistan Institute of Medical Sciences, Islamabad, Pakistan. They were systematically and randomly recruited when they came for regular physical examinations at the hospital. Ethical approval was sought from the institution (Reference no. F. 1-1/2015/ERB/SZABMU) and written informed consent was obtained from the participants before conducting the study. The total duration of the study was 3 months.

Individuals aged over 15 years with a completely intact dentition with functional occlusion were included in the study. Those who had a history of temporomandibular dysfunction or bruxism, dental or skeletal cross bites, maxillofacial trauma, oral malignancies, and other conditions such as microstomia, oral burn contracture that can effect mouth opening were excluded.[3] The mouth opening was measured based on the method described in previous study.[19] An intraoral, extraoral, and Temporomandibular joint (TMJ) examination was performed before measuring mouth opening. A normal mouth opening is measured 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 at the widest opening.[15] While sitting comfortably in an upright position on dental chair, a participant is asked to open the mouth as wide as possible. Then the total distance from incisal edge of the upper incisor teeth to the lower incisor edge was measured in millimeters using a fiber ruler. Three measurements were taken for each individual and the average was used in the analysis. All the measurements were performed by a single examiner. Participant’s gender and age were also recorded.

Statistical analysis: A descriptive analysis was carried out to obtain the mean, standard deviation (SD), minimum, and maximum values. Independent t-tests were used to examine differences in mouth opening between genders, and analysis of variance was used to examine the difference between age groups at 5% significant level. The analysis was performed using the Statistical Package for the Social Sciences (SPSS) (IBM SPSS, Chicago, Illinois) version 22.0.


A total of 500 subjects were approached and 497 (99.4% response rate) subjects aged between 15 and 65 years were examined. There were slightly more males (52.3%) than females (47.7%) in the sample. The mean MMO for male and female subjects was 58.2mm (SD = 7.92mm) (95% confidence interval [CI]: 57.23, 59.18mm) and 47.3mm (6.84) (46.43, 48.18mm), respectively [Table 2]. The mean MMO was statistically significantly wider in the males than that in the females (mean difference = 10.9mm, SE = 0.66, 95% CI: 9.60, 12.2, P < 0.001). The difference was also significant in all age groups except in the 56–65 years [Table 3]. The mean MMO was found to be smaller with increasing age in both male and female participants.{Table 2}, {Table 3}


The objective of this study was to describe the MMO for the northern Pakistani population. The result from this study is consistent with that of a study by Sohail and Amjad[7] (2011) for Pakistani’s young adults less than 25 years. In addition, it described the MMO for a wider age range for the population. The findings are also consistent with other populations in relation to the gender differences and increasing age trend.[9],[18] The data showed that the males in Pakistani population had wider mouth opening than the females and that the width of MMO declined with increasing age. The MMO of the sample was similar to a Swedish study and; greater than some of the Asians, Africans and some of Europeans reports [Table 1].

The MMO is generally determined by the genetic factors such as sex and ethnicity and these are related to the anthropometric measures such as height, weight, and stature, size of the mandibular, and cranial base.[3],[15],[20] Anatomical bone structures of the head and face, particularly the mandible, are generally larger in males, thus significantly influencing the size of mouth opening.[21] Because the overall skeletal structure, head and face are generally influenced by the ethnic background, the physically larger sized populations tend to have wider MMO.[3] This is partly the reason for the variation in MMO between racial groups. Physically, the average height of Pakistani adults at approximately 1.72 m in males and 1.59 m in females, which is not very different from the Swedish at 1.78 and 1.66 m, respectively; however, they are much larger than the Nepalese at 1.62 and 1.51 m, respectively.[6],[22] Correspondingly, the MMO of the Pakistani is similar to the Swedish than the Nepalese, although the latter is closer to Pakistani geographically and culturally.

A decrease in the MMO over time is the consequence of aging process, which is related to the weakening of the muscle tone and strength and remodeling of bony facial structures. A similar observation is also found in previous studies irrespective of sex and TMJ status.[3],[9],[10],[11],[17] Older patients may experience a greater strain when the MMO is being measured. In the process, they have to hold the mouth open at its widest for a few seconds. This action forces the masticatory muscles to contract in an unnatural manner and when performed repeatedly, particularly over a short time span, the mouth opening tends to decrease. This resulted in the first measurement to be the greatest and it gradually decreased because muscle power is lost in the succeeding measurements, hence introducing bias in the measurements.[6],[23] To minimize this bias, this study used an average of three measurements instead of two and allowed for a slightly more conservative and normal mouth opening instead of a forced maximum opening. An active or forced mouth opening method may introduce more errors because of the variation in the forces that are applied to split the jaws.[19] In this study, all the participants were positioned in an upright and relaxed position as it was more effective[24] compared to a retracted head position.[12] Although the measuring technique used was simple and noninvasive and had lower risk of error, it may still be affected by incisors that are traumatized, worn, absent or not erupted completely, or by malocclusion, which were not addressed in this study.

One of the limitations of this study is its representativeness. Because the participants were recruited from one location, where the source of the population was from the city and its peripheral areas, and the population varied in its ethnicity, the inference was limited to those from the northern of Pakistan. One advantage of this study is that the age range is much wider than a previous report of the Pakistani population.[7] It was somewhat wider than other previous studies, which was between 20 and 60 years.[10],[25] The availability of the MMO values for the youngest age group is useful when planning an orthognathic surgery because the skeletal growth is almost complete (99%) at 14.9 and 16.5 years in females and in males, respectively.[8] The power of the study, as indicated by the narrow confidence interval range (1.75mm for females and 1.95mm for males), was reasonably adequate for clinical application. A further research could be carried out for the same population to account for the variation caused by ethnic groups of Pakistani population and also clinical conditions such as traumatized, worn, and malocclusion in a multicenter setting.

This study found that the mean MMO of Pakistani were among the widest that has been reported, the width in the males was significantly greater than females, and that it decreased with age.

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Conflicts of interest

There are no conflicts of interest.


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