20. Which of the following Is true for secondary dontin? A. After root formation,its formation begins B. Starts to form as a result of low level Irritants C. Formation begins as a result of high lovel irritants D. It is the dentin formed before root formation 22. Which Black classifleation does the carlos in the Ungual groove of the upper left first molar tooth belong to? A. I B. Il C.v D. VI 22. Which of the following is a function of the burnishor? A. For the removal of proximal overhanging amalgam B. Forming motal matrix bands C. In the first condensation of amalgam D. Roughening the amalgam surface 45. Which of the following is the most proforred Instrument grasp? A. Modifled palm a thumb B. Reverse pen grasp C. Palm a thumb grasp D. Modifled pen grasp 24. Which of the following to Incorrect for onamet? A. It is harder than dontin B. Its organic content is higher than that of dentin C. Its light transmittance is higher than that of dontin D. It is more rigid than dontin 75. Which Black classification does the Mount or Nume 2 cavillar correspond to? A. 3

20. The correct answer is A. After root formation, its formation begins. Secondary dentin is formed after the root formation has completed. It is a response to stimuli such as injury or infection and helps to protect the tooth.<br /><br />24. The correct answer is D. VI. The caries in the ungual groove of the upper left first molar tooth belongs to Black's classification VI. This classification refers to caries located in the pits and fissures of the teeth.<br /><br />22. The correct answer is A. For the removal of proximal overhanging amalgam. A burnisher is a dental instrument used to smooth and polish the surface of amalgam restorations. It is particularly useful for removing proximal overhangs and creating a smooth finish.<br /><br />45. The correct answer is C. Palm a thumb grasp. The most proficient instrument grasp among the options provided is the palm a thumb grasp. This grasp allows for greater control and precision during dental procedures.<br /><br />24. The correct answer is C. Its light transmittance is higher than that of dentin. Enamel is the hardest and most mineralized substance in the human body. It is harder than dentin, has a higher organic content than dentin, and is more rigid than dentin. However, its light transmittance is lower than that of dentin due to its high density and mineral content.<br /><br />75. The correct answer is A. 3. The Mount or Nume 2 cavitation corresponds to Black's classification 3. This classification refers to cavities located in the proximal surfaces of the teeth, specifically between the contact points.