The present study was carried out on the patients visiting the Department of Oral Medicine and Radiology, Vyas Dental College and Hospital. The study was carried out during the span of 6 months from June 2013 to December 2013. Patient who were willing to participate in the study and were falling in the age specified by WHO (5, 12, 15, 35-44 and 65-74) [6] were included in the study as per selective sampling. Patients who had any source of pulpal infection, any known systemic illness, radiographic evidence of developmental anomalies or pathologies of the teeth and jaws were excluded from the study. Based on these criteria 750 patients were examined (150 in each age with equal number of males and females to standardize the comparison) for the presence of IO in the jaw bone.

After carrying out complete clinical examination, a digital panoramic radiographic was taken for each patient [Table/Fig-1]. Kodak 8000C extraoral imaging system was used for digital OPG. This digital X-ray machine was operated at 8-12mA, the peak kilovoltage was ranging from 70-80 depending on the estimate of subject’s jaw size. The digital images were then saved and interpreted.

[Table/Fig-1]:

OPG of an adult female revealing Idiopathic Osteosclerosis on left body of mandible in the region of 33

The lesions which did not show any signs of inflammation, that were well demarcated, were identified as IO.

The presence or absence of IO was then entered in the study performa which consisted of data pertaining to date, patient name, age, gender, jaw involved, and area in the jaws involved.

Two examiners interpreted the radiographs. Training of the examiners was done by a staff member. Each examiner viewed the radiograph twice for the presence of IO in a time interval of four days. When both intra and inter examiner results matched its presence was conformed. In case when the result did not matched, a mutual decision was obtained by both the examiners. Inter examiner reliability test was done by using kappa statistics and score was found to be.90 (Excellent).

The data obtained was then tabulated and subjected to statistical analysis using SPSS version 18. Chi-square was used to find relation between the jaws and the various areas of the jaws.

OPGs of 750 study subjects of the age of 5, 12, 15, 35-44 and 65-74 (150 each) were examined, among them there were equal number of males and females 375 each [Table/Fig-2].

Among the total study population 89 (11.8%) were found to be suffering from IO out of which 27 (7.2%) were males and 62 (16.53%) were females [Table/Fig-3].

It was observed that maximum number of IO cases was seen among the age group of 35-44 y 33 (22.0%) and minimum in 5 y 9 (6%) [Table/Fig-4].

When chi-square test was used to find association between maxillary and mandible jaws IO, a significant association was observed (p=0.001) [Table/Fig-5].

Similarly when chi-square test was used to find association between areas in maxillary and mandible jaws IO, it was found that a significant association was both in the areas in maxillary and mandibular arches [Table/Fig-6].

The prevalence of IO varies from 3.3% to 31% among various populations worldwide [7]. Various theories such as developmental aetiology, reactive response of the bone to inflammation and trauma have been reported in various studies [4,8]. A study done in China stated that Chinese and Japanese populations have greater chances of developing IO as compared to the western population [9]. To the best of our knowledge, this is the first study carried out among the rural population of Western India. In the present study the prevalence of IO was found to be 11.8%, which is much higher than that observed by Geist and Katz [10] 5.4% and Yonetsu et al., [11] 6.1%. The prevalence of IO among several countries was found to range from 2.3% to 9.7 % [1,4,12]. In the present study the prevalence of IO was higher among women 62 (16.53%) as compared to that in men 27 (7.2%), similar results were observed in the study done by Miloglu et al., [8], McDonnell [9] and Geist and Katz [10]. In the present study it was found out that with the advancing age the prevalence of IO decreases and this finding is supported by the Kawai et al., [7]. In the present study, both IO was found in the 3^rd and 4^th decades of life. A possible explanation might be increased tooth caries and pulpal infections with increased age. The high prevalence of IO lesions in the 3^rd and 4^th decades coincides with the maximum bone mass acquisition in these periods.

Idiopathic Osteosclerosis is most commonly observed in the mandibular jaw 81 (21.6%) as compared to maxillary jaw 8 (2.1%). In the mandibular jaw IO was mostly seen in the posterior region 43 (11.4%) followed by canine region 31 (8.2%), Meryem toraman alkurt et al., [13] also observed similar results in his study. Garau V et al., [12] and Sisman Y et al., [14] also observed similar results in their studies. Since IO lesions are most frequently found located in the premolar and molar areas, they might represent residual roots from deciduous molars, resorbed and replaced by sclerotic bone [15]. These findings could be explained by the fact that the common superposition of anatomic structures makes maxillary lesions harder to detect from panoramic radiographs when compared to mandibular lesions [15]. The premolar region in the mandible may experience concentrated inner distortion, and areas of the mandible near the mental foramen receive sufficient blood supply to easily form bone masses [5].

In the present study it was observed that the prevalence of Idiopathic Osteosclerosis is higher among the females as compared to males and mostly seen among the 3^rd and 4^th decade individuals. The dentist can help to identify these lesions and in turn help patients from developing any complication.