The cement under MOD amalgam have this character.. High modulus of elasticity - stiff

The cement under MOD amalgam have this character:

• a. High modulus of elasticity (stiff)***
• b. Low modulus of elasticity (stiffness).
• c. The high modulus of elasticity prevent of bonding and decrease tensile strength.
• d. Both a &c.

The correct answer is d. Both a & c.

Here's why:

- High modulus of elasticity (stiffness):

This is true. Cement used under MOD amalgams (Mesial-Occlusal-Distal fillings) typically has a high modulus of elasticity, making it strong and rigid. This can provide support for the amalgam and help prevent fractures.

- Low modulus of elasticity (stiffness):

This is incorrect. As mentioned above, cement under MOD amalgams needs to be stiff for strength and support.

- The high modulus of elasticity prevents bonding and decreases tensile strength:

This is also true. While a stiff cement provides support, it can also make it more difficult to achieve a strong bond with the tooth structure. Additionally, the high stiffness can lead to increased stress on the interface between the cement and the tooth, potentially decreasing tensile strength (resistance to pulling forces).

Therefore, while a high modulus of elasticity is beneficial for strength and support, it can also present challenges in terms of bonding and tensile strength. This is why the choice of cement for MOD amalgams requires careful consideration of the specific needs of the restoration and the tooth structure.

Additional Points:

Here are some additional points to consider:

• The ideal cement for MOD amalgams should have a modulus of elasticity that is similar to the tooth structure. This helps to minimize stress at the interface and promote a strong bond.
• Other factors to consider when choosing a cement include its working time, compressive strength, and radiopacity.
• A dentist will carefully select the appropriate cement based on the individual case and the specific needs of the patient.