1. Rounded internal line angles II. Exclusion of weakened tooth structure III. Adequate thickness of restorative materials 12. Which of the above is/are necessary for the primary resistance form? A) I B) I,II C) I,II,III ) I,III ) II,III

C) I, II, III<br /><br />All three factors mentioned are necessary for the primary resistance form:<br /><br />I. Rounded internal line angles: This helps in creating a smooth surface for the restoration and prevents the formation of sharp angles that could lead to fractures.<br /><br />II. Exclusion of weakened tooth structure: It is important to exclude any weakened or compromised tooth structure from the area to be restored to ensure the longevity and integrity of the restoration.<br /><br />III. Adequate thickness of restorative materials: The restoration needs to have sufficient thickness to withstand the forces of mastication and prevent wear or damage over time.