On the basis of the case study and the related studied concepts. Rohan had a toothache and went to the dentist for investigations. After examining him, the doctor found a plaque on his teeth. The sticky, colorless or pale yellow film was deposited on his teeth due to the left food containing sugars etc on the teeth it might be due to improper cleaning of the teeth. The unhygienic conditions result in the formation of this layer and thus proper cleaning and maintenance of oral hygiene is necessary. Name the hardest material found in our body.