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Year : 2020  |  Volume : 7  |  Issue : 4  |  Page : 177-181

Prevalence of Torus mandibularis and its association with para-functional activity in tertiary care centre in Shimla, H.P., India: A hospital based cross sectional study

Department of Oral Medicine and Radiology, HPGDCH, Shimla, Himachal Pradesh, India

Date of Submission15-Jun-2020
Date of Decision03-Jul-2020
Date of Acceptance27-Jul-2020
Date of Web Publication1-Dec-2020

Correspondence Address:
Neeta Sharma
Department of Oral Medicine and Radiology, HPGDCH, Shimla, Himachal Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jdrr.jdrr_62_20

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Introduction: Oral tori are bony growths present in oral cavity and are not considered as pathological lesions. Torus mandibularis (TM) is usually present in lingual aspect of alveolar process in canine-premolar region of mandible. The objective of the study is to determine the TM' prevalence among outpatients attending tertiary care center and its relevance with parafunctional activities. Materials and Methods: The study was conducted in the out patients attending the hospital between December 2017 and May 2019. Fourteen thousand and two hundred and eight patients were screened for the presence of TM as per inclusion and exclusion criteria. The data were collected and subjected to the statistical analysis. Results: Out of 14,208 patients, 157 patients were presented with TM. The prevalence found to be 1.1%. Tori were more frequent in males than females. The most commonly observed type was bilateral solitary type. The association of TM with parafunctional activities and temperomandibular disorder was found to be significant. The higher frequency of TM was seen in the subjects residing at high altitudes. Discussion: The prevalence of TM in our study was found to be low. The study was undertaken to record the preliminary data regarding TM in this region and its association with parafunctional activity. Conclusion: We suggest performing thorough clinical examination and imaging to rule out underlying parafunctional activity, if TM is incidental finding.

Keywords: Parafunctional habits, prevalence, tempero-mandibular disorders, torus mandibularis

How to cite this article:
Prasad R G, Sharma N, Prakash R. Prevalence of Torus mandibularis and its association with para-functional activity in tertiary care centre in Shimla, H.P., India: A hospital based cross sectional study. J Dent Res Rev 2020;7:177-81

How to cite this URL:
Prasad R G, Sharma N, Prakash R. Prevalence of Torus mandibularis and its association with para-functional activity in tertiary care centre in Shimla, H.P., India: A hospital based cross sectional study. J Dent Res Rev [serial online] 2020 [cited 2022 Nov 27];7:177-81. Available from: https://www.jdrr.org/text.asp?2020/7/4/177/302056

  Introduction Top

Kupfer and Bessl Hagen (1879) introduced the term “torus” for a well-defined, convex, slow growing, bone outgrowth made of dense cortical layer and scanty spongy bone with mucosal covering.[1] Anthropologist have noted that the frequency of tori differ in different populations.[2] The prevalence of torus mandibularis (TM) is 0.5% in Brazilian Indians; 3.2% in Nigerians; 31.9% in Thai; and 74% in Japanese population.[3] The etiology of its development is unknown and several factors have been proposed for its formation such as genetic, masticatory stress, developmental anomalies, infection, malnutrition and discontinued growth, occlusal overload.[4],[5] Torus is considered to be congenital and benign condition and are named according to the site it present like “TM” on lingual aspect of mandible and “Torus palatinus” on midline of hard palate.[6] TM is hyperostosis that protrudes from the lingual aspect of the mandibular alveolar process, usually near the premolar teeth. It tends to grow slowly and continuously, but have been found to stop growing spontaneously in the absence of teeth.[7] Its size can range from few millimeter to centimeters. TM can be categorized as unilateral-solitary, unilateral-multiple, bilateral-solitary, and bilateral-multiple.[4],[5]

TM is incidentally discovered during routine oral examination as they rarely are symptomatic. Patients with tori may experience discomfort if it increases in size and interfere with speech and mastication; or if it is prone to traumatic ulceration.[7] The surgical removal is done in such cases and also if it interferes the construction of dental prosthesis. On periapical radiograph, it appears as a radiopaque shadow usually superimposed on the roots of premolar-molar and rarely on canine and incisors. On occlusal radiograph, it appears as radiopaque knobby protuberance from lingual surface of mandible. The internal aspect is homogeneously radiopaque.[8],[9] The objective of the present study is to estimate TM's prevalence among the out patients visiting dental hospital and to obtain preliminary data on this entity; and also to evaluate its relevance with occlusal stress induced by parafunctional activity, dietary habits, temporomandibular dysfunction (TMD), and geographical location (altitude).

  Materials and Methods Top

The study was conducted in the department of oral medicine after obtaining ethical clearance from institutional ethical committee and written informed consent from the patients, from December 2017 to May 2019. The data were collected after screening 20–60 years of age group patients for mandibular tori by visual and palpatory examination. A detailed case history including geographical location, dietary habits, parafunctional habits, TMD, and number of teeth present were noted. The number and extent of mandibular tori was determined by palpation and recorded as solitary/multiple and unilateral/bilateral. A radiographic examination (Intra-oral periapical radiograph (IOPAR) and occlusal radiograph) and alginate impression were taken for each patient with mandibular tori. The data were entered into MS Excel sheet and statistically analyzed on Epi-Info(ver-7 CDC.gov U.S. Department of Health & Human Services USA.gov). The categorical variables are expressed in frequency and percentage; continuous variables are expressed in mean plus standard deviation. The association between various variables is analyzed by Chi-square test (statistically significant if P < 0.05).

  Results Top

A total of 24,613 patients reported to the department between December 2017 and May 2019. Out of them, 14,208 patients of age group 20–60 years were screened for the presence of TM. Of 14,208 patients, 157 patients presented with TM, with the prevalence of 1.1%.

[Table 1] reveals distribution of subjects according to gender and age group. Of 157, 92 (58.6%) were male and 65 (41.4%) were female. The most affected age group was 31–40 years (42 subjects), followed by 21–30 (42 subjects), 41–50 (37 subjects), and 51–60 (34 subjects) [Graph 1]. [Table 2] shows the distribution of TM according to number and site. The bilateral solitary type was the most common type present in 123 subjects (78.3%) and least common type was unilateral multiple type (1 subject, 0.6%) [Graph 2]. [Table 3] reveals the association of parafunctional activity. The parafunctional activity was more commonly reported in male subjects (69 subjects [67.5%] as compared to female subjects (37 subjects [32.5%]) [Graph 3]. The association was found to be statistically significant (P = 0.024). [Table 4] shows the association between TM and TMD which was found to be significant (P = 0.083). [Table 5] shows the distribution of TM subjects according to its location (altitude). Out of 157 subjects, 67 (42.7%) subjects belonged to altitude of 1700–2199 m, followed by 40 (24.8%) subjects from 2200 to 2699 m, 32 (20.4%) subjects from 1200 to 1699 m, 10 (6.4%) subjects from 700 to 1199 m, and 2 (1.3%) subjects from 3200 to 3600 m altitude [Graph 4].
Table 1: Distribution of the participants with torus mandibularis according to gender

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Table 2: Association between gender and parafunctional activity

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Table 3: The association between age groups and parafunctional activity

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Table 4: Association of torus mandibularis with temperomandibular disorder

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Table 5: Association between gender and temperomandibular disorder

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  Discussion Top

Oral tori are bony growth present in the oral cavity and are not considered as pathological lesions.[4] The etiology is still unknown and several factors such as genetic causes, racial differences, developmental anomalies, masticatory stress, infection and malnutrition as well as growth disturbances have been considered to be the causative factors. At present, the etiology of tori is considered multifactorial.[10],[11],[12],[13],[14],[15],[16],[17] In a recent review by Garcia, explained the formation of tori by Osteogenic-Periosteal Stretch Hypothesis, according to which the chin is prevented from undergoing excessive deformation due to the mental process. Humans lack the simian shelf but have instead developed an external chin to strengthen the weakest part of the mandible. Thus, the morphology of the mandible localizes torus formation to the premolar region as the mandibular body buckles medially due to a combination of muscular compression and tooth orientation directed by the maxilla. However, evidence for this hypothesis is lacking.[18]

TM is seen on medial aspect of body of the mandible and can be categorized as unilateral-solitary and bilateral-solitary, unilateral-multiple and bilateral-multiple, and bilateral-compound. The dimension of tori can reform throughout life, but majority are <2 cm in diameter. It may increase in size in the early adult life, but may decrease due to bone resorption in the older age group.[4],[5]

The prevalence of TM in our study was 1.1% which is comparable to Shah et al.'s study which had 1.4% prevalence and prevalence in various parts of world is summarized in [Table 6].[4],[19],[20],[21],[22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32],[33],[34] The prevalence may vary among similar ethnic groups living in different areas, or different ethnic groups living in same area suggested by Eggen and Natvig[35] In our study, higher prevalence was found in males (92,58.6%) than females (65,41.4%). This finding is in agreement of most of the studies.[4],[5],[20],[24],[29] Alveslo et al. suggested that sexual dimorphism in the manifestation of TM might be a consequence of the effect of Y chromosome on growth, occurrence, expression, and timing of the development of mandibular tori.[36] The increased prevalence of tori was seen in 31–40 years of age group in our study which is in accordance with the studies in literature [Graph 1].[21] The effect of environmental, dietary, and genetic factors including masticatory stress and nutritional factors have been reported in the literature.[1],[3],[7],[11],[12],[13],[14],[15],[16],[25],[37],[38],[39] Eggen and Natvig had explored the effect of nutrition in the tori formation and suggested that relatively higher prevalence of tori is seen in coastal regions. This might be explained by the fact that fish constituted a major part of diet which possibly supplies higher levels of polyunsaturated fatty acids andcholecalciferol (Vitamin D), which is involved in bone development.[35] Seafood consumption is not as common in the Indian subcontinent especially in the Himalayan region as in other parts of the world. This might be one reason for low prevalence reported in our study. Our study found a strong correlation between TM and mixed dietary habits. Kerdpon and Sirirungrojying found the people who consumed a soft refined diet.[22] Our study also showed bilateral solitary TM was the most prevalent type of TM [Graph 2], which is in accordance with other studies in literature. We also found the most TM was located between canine and premolar region while Shah et al. reported that most TM were found between first and second premolar.
Table 6: Torus mandibularis prevalence table[4],[19],[20],[21],[22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32],[33],[34]

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Our study found a strong association between TM and parafunctional activities as presented by clenching and grinding and TMD [Graph 3]. It is reasonable and generally believed that masticatory stress plays a role in induction of TM suggested by various studies. Eggen and Natvig had also correlated the high prevalence of TM with increased masticatory stress during parafunctional habits. Kerdpon and Sirirungrojying also found a strong association between clenching and grinding and the presence of TM reported in Thai population.[22] Igarashi et al. concluded that high degree of dental attrition is one of the indicators showing that teeth and mandible suffer occlusal stress.[37] Johnson et al. proposed that TM may be formed by the shock of force on abraded cusps and right angle transmission of the force from buccal surface of posterior teeth to lingual surface of the alveolar process. Wolff's law states that the bone will remodel itself to become stronger, if loading on the bone increases. The undue stress and stretch over the osteogenic periostea during parafunctional activity may lead to bone deposition in the form of tori. The presence of TM might be useful as cue to look for the sign of parafunction during routine oral evaluation.[21],[22]

This study also found that population residing at higher altitudes between 1700 and 2200 m [Graph 4] has a higher prevalence of TM as higher altitude population is exposed to inhospitable climate where the nonvegetarian food is found more than vegetarian food. Kolas et al. also found higher prevalence in population living in northern latitudes of Europe and has principal diet consisting of animal food, thus claiming that TM is functional adaptation rather than racial characteristic.[40] High altitude environments also characterized by lower partial pressure of oxygen relative to low altitude environment at similar latitudes.[41] The relationship of higher frequency of TM in high altitude hypoxia may be a topic of concern to be explored in future studies.

Tori are usually asymptomatic clinical findings usually requiring no treatment, unless chronic trauma, and pre-prosthetic surgery is required for its removal.[4]

  Conclusion Top

This study was conducted in hospital settings to record the preliminary data regarding TM in this region. The higher prevalence of TM in patients with parafunctional habits and TMD was found in our study. Therefore, we suggest if TM is present then careful clinical examination and imaging should be performed to rule out underlying TMD and parafunctional activities. We suggest cohort study should be conducted to explore if TM is sign of TMD and parafunctional activities.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]

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