Prevalence and Distribution of Oral Mucosal Lesions and Normal Variants among Nepalese Population

Background Oral mucosa is encountered by various lesions and normal variants. Some are not to be worried about, whereas others may be of significance. Knowing the prevalence of oral mucosal lesions in a particular region helps better evaluate, diagnose, and, thus, manage these lesions. Objectives To assess the prevalence and distribution of oral mucosal lesions and normal variants among various age groups, genders, and sites of the orofacial region. Methods This cross-sectional study was conducted in the Department of Oral Medicine and Radiology, KIST Medical College and Teaching Hospital from January 2021 to March 2021. Three different proformas were designed according to age, gender, and location of lesions for entry as per the WHO's guide. The obtained data were entered into a Microsoft Excel sheet for frequency analysis by SPSS, and the results were tabulated. Results Among the records of 16572 (9703 (58.55%) males and 6869 (41.44%) females) OPD patients, 3495 (21.08%) (1934 (55.33%) males and 1561 (44.66%) females) had OMLs and 2314 (13.96%) (1626 (70.26%) males and 688 (29.73%) females) had normal mucosal variants. The most commonly seen OML categories were tobacco-associated lesions, i.e., 2056 (34.07%), tongue lesions, i.e., 1598 (26.48%), oral potentially malignant disorders, i.e., 815 (13.50%), ulcers i.e., 728 (12.06%), and infectious lesions, i.e., 256 (4.24%). Conclusion The Nepalese population has a wide range of oral mucosal lesions and normal variants, and this study has attempted to have baseline data for the same. The most common OML was smoker's melanosis.


Introduction
The orofacial region is affected by various oral mucosal lesions (OMLs).Oral mucosa is explicitly affected by seven oral potentially malignant disorders [1].Various other OMLs include several types of cysts, benign and malignant tumours, inflammatory lesions, lesions associated with tobacco, areca nut [2], betel nut chewing [3], and others; immune-mediated lesions like recurrent aphthous stomatitis (RAS) and oral pemphigus, which pose a challenge in the management and may become life-threatening if early diagnosis fails.These lesions cause disturbance in day-to-day activities as they interfere with the consumption of food, causing pain, burning sensation, facial asymmetry, and others.In contrast, other normal variants of oral mucosa do not cause harm but can be misdiagnosed as a potentially life-threatening condition.This makes it necessary for us to have the proper knowledge about oral lesions (OLs) and the normal variants for proper management.These lesions vary depending on geography, race, culture, ethnicity, food, or deleterious habits [4].Therefore, adequate knowledge about the prevalence of oral lesions is of great significance as it helps in the prevention, correct diagnosis, and management.
The prevalence of OMLs and normal variants is between 10.8% and 61.6% among the various populations [5].Epidemiological studies of OLs are still lacking when compared to the studies of dental caries or periodontal diseases [6], and just two studies based on this topic have been reported in Nepal to date [7,8].Those studies were not focused on the prevalence of normal variants and OMLs; instead, they were histological studies done on pathological samples, so they could not find the overall prevalence.This prompted us to conduct a study on the prevalence of oral lesions and normal variants of oral mucosa from previous dental records of patients who had visited the dental hospital in Lalitpur within the provided time frame.
The objectives of this study were to study the prevalence and distribution of various oral mucosal lesions and normal variants among various age groups, genders, and sites of the orofacial region.No. 077/078/26) The census sampling method was used for all the cases of oral lesions recorded from January 2016 to December 2019, meeting the inclusion criteria.

Inclusion and Exclusion
Criteria.Clinically or histologically diagnosed as any of the oral mucosal lesions, along with data of the location/site of the lesion.
Data including clinical/histological diagnosis, age, gender, and site/sites of the lesion were included.Record with incomplete demographic or clinical data was excluded.Also, the same patient was not included again as a new patient, which was done with the help of the unique OPD number provided to each patient.

2.
3. Data Sources.Data collection was done manually by going through the previous outpatient records of the oral medicine and radiology department.Three different proformas were designed for entry according to age, gender, and location of lesions, which was done taking into consideration the WHO's guide to epidemiology and diagnosis of oral mucosal diseases and conditions [9].

Result
Among the records of 16572 OPD patients, 3495 (21.08%) had OMLs, 2314 (13.96%) had normal mucosal variants, and 10763 (64.94%) had normal oral mucosa.A total of 55 types of OMLs were noted among the 10437 lesions.These 50 types of OMLs were categorized into 11 different groups based on common characteristics, and one group was categorized as others, which could not be categorized otherwise.More than 45% of individuals had more than one OMLs and/or more than one normal variant; therefore, the total OMLs were 6033, and the total normal variant was 4404.

Discussion
The prevalence of oral and maxillofacial diseases varies depending on the region, country, and data source [4].An oral lesion is any abnormal alteration in colour, surface aspect, swelling, or loss of integrity of the oral mucosal surface.Although a proportion of OMLs are benign and require no active treatment, some may present with significant pathology.Besides, OMLs can interfere with the daily quality of life in affected patients [6].Oral lesions are usually mystified by their aetiology, which may be viral, fungal, bacterial, related, or even without definite aetiology.Understanding the prevalence of oral mucosal lesions may facilitate the prevention, appropriate diagnosis, and prompt treatment of the disease [7].There is a lack of epidemiological studies based on oral mucosal lesions in the Nepali population, which led us to conduct this study in a tertiary centre in the Lalitpur Region, where patients visit for various dental treatments, as well as are referred from various clinical centres in and out from the Lalitpur Region.To the best of our knowledge, this study was the first attempt to get a prevalence of various oral mucosal lesions among the Nepalese population.
Tongue lesions were observed among 26.48% of our study population, and it was quite higher in studies by Avcu et [26].
The prevalence of fissured tongue in our study was 3.43%, which was relatively low as compared to the study   [27] but higher than the studies by Kumar et al. (0.2%) [14] and Oivio et al. (1.1%) [5].
The prevalence of oral lichen planus was found to be 2.55% in our study population, which was higher than the studies by Saraswathi [29] but was in a comparable range.It was higher than the global estimate of 1.01% [40].
The prevalence of oral submucous fibrosis was found to be 1.81% which was similar to the study by Bhatnagar et al.
Salivary gland disorders were found to be 0.34% in our study group, which was relatively low than the study by Gambhir et al. (2.9%) [10] and Amaral et al. (8.6%) [4].
Mucocutaneous lesions were present among the 0.15% of the study population, which is again relatively low as compared to studies by Gambhir et al. (1.8%) [10].
The prevalence of Fordyce's granules was 8.84% in our study population, which was more than the studies by Oivio et al. (1.2%) [5] [20].
The prevalence of leukoedema was 0.72% in our study population which was comparable to studies by Mumcu et al. (refer for more) (0.4%) [13] [27], and in contrast, OMLs were most commonly found among the females in studies by Al-Mobeeriek et al. (57.7% females and 42.3% males) [21], and Castellanos and Díaz-Guzmán (1.4 : 1 male to female ratio) [28].In contrast, studies done by El Toum et al. [6] and Mumcu G et al. [13] did not find any gender difference.

Age Groups.
Children in the young age group, i.e., 0-20 years, had a very low prevalence of OMLs in our study population, i.e., 37.36%, as compared to the study by Nair et al. (64.4%) 32 but higher than the studies by Jahanbani et al. (28%) [33].
OMLs were most frequently seen among the age group of 41-50 years followed by 31-40 years, which was similarly seen in the study by Bajracharya et al. (31-40 years) [8].
Oral candidiasis was seen most commonly among the elderly population aged >61 years.
OPMDs, malignancies, and tobacco-associated lesions were found most commonly among 31-40 age groups, in contrast to the melanin pigmentation and fissured tongue seen in the study by Mumcu et al. [13] among the elderly population.
The prevalence of aphthous ulcer among 11-20 years was 0.79%, which was relatively low as compared to the study by Parlak et al. (3.6%) in the age group of 13-16 years only [15] and Yanez et al. (6.9%) in the age group of 3-13 years [35].
The least common location for OMLs was the floor of the mouth (1.33%) in our study, which was different from gingiva in studies by Bajracharya et al. [8] and Bhatnagar et al. (0.4%) [27].
The prevalence of OMLs was relatively higher among the studies that were done on records of biopsy [7,8,10], and they will be definitely as compared to the screening samples of regular dental patients as in our study.Compared to our study, variations and differences in the prevalence of various OMLs and normal variants have been noted.This could be attributed to the very different geographical location, and none of the studies have been done near our study sample, which is relatively higher than previous studies in different geographical locations.Few of the studies took only young children or middle-aged or elderly populations, and none took a wide range of age groups (all age populations).The differences in the mucosal lesion can also be attributed to different food habits, cultural practices, and living environments.
Our study's limitation was that the population was from a single tertiary centre in Nepal, which gives region-specific data.We would suggest a multicenter countrywide further study to have a more specific prevalence.Another limitation of this study was that it was done retrospectively, and the histopathological confirmation of all the lesions was not done.

Conclusion
It was concluded that there is a wide variation in the prevalence of oral mucosal lesions worldwide, and the prevalence is specific to a particular region only.Our study has concluded that the Nepalese population has a wide range of oral mucosal lesions and normal variants, and this study has attempted to have baseline data for the same.OMLs were seen most commonly among males and the 41-50 age group.The most common OML group is related to tobacco, among which smoker's melanosis is the most common one.Smoker's melanosis was the most predominant lesion among the males in the 50-60 year age group.9 BioMed Research International

2. 1 .
Study Design.This cross-sectional study was carried out in the Department of Oral Medicine and Radiology, KIST Medical College and Teaching Hospital, from January 2021 to March 2021.Ethical approval was given by the institutional review committee of the same institution.(IRC Ref.

2. 4 .
Statistical Methods.The obtained data was entered in a Microsoft Excel sheet for frequency analysis by IBM SPSS Statistics for Windows, version 27 (IBM Corp., Armonk, N.Y., USA), and the results were tabulated.

Table 1 :
(a) Prevalence of oral mucosal lesions-overall and among oral mucosal lesions.(b) Prevalence of normal variants.

Table 2 :
(a) Gender distribution of oral mucosal lesions.(b) Gender distribution of normal variants.

Table 3 :
(a) Age-wise distribution of oral mucosal lesions.(b) Age-wise distribution of normal variants.