Shorts

Roughening the old restoration and re-etching it allows for better bonding of the new composite material.

Carbon steel can be made harder than stainless steel, allowing it to maintain a sharp cutting edge longer during operative procedures.

Failure of a cast to seat properly on the cast during the restoration process can be due to various factors such as distortion during fabrication or changes in the cast material. To overcome this, the cast can be scraped with a sharp instrument to remove any excess material that may be preventing proper seating. Washing the casting with HCI (hydrochloric acid) may help to clean and smooth the surface, but it is not a common practice for this specific purpose. Forcefully positioning the casting can cause damage to the cast and is not recommended. If the discrepancy is more than 0.3 mm, it is generally advised to discard the cast and make a new one to ensure a precise and accurate fit.

The bonding in porcelain fused to metal (PFM) restorations is achieved through a combination of both chemical and mechanical mechanisms. 

Explanation: In a conventional Class III amalgam cavity preparation, the axial wall should be straight and parallel to the long axis of the tooth. This design ensures that the restoration has adequate resistance form and is less likely to dislodge under occlusal forces. The wall being deeper incisally than gingivally helps to maintain the integrity of the tooth structure and provides a stable base for the amalgam restoration.

Retention grooves in a class V cavity for non-adhesive restoration are placed in the mesioaxial and distoaxial line angles. These grooves help hold the restoration in place by providing mechanical retention and reducing the risk of microleakage.

Amount of force needed to condense direct filling gold depends on the surface area of the condenser. The larger the surface area, the less pressure is required to achieve proper condensation. The force applied affects the compaction of the gold, but it is the size and shape of the condenser point that dictate the actual pressure exerted on the material.