100% of methyl mercury is absorbed from the gut. After absorption methyl mercury binds to hemoglobin, circulates systemically and is distributed to all organs, including the brain

Explanation: The lingual approach to the distal surface of a canine for Class III amalgam restoration is primarily related to aesthetics. This approach minimizes visibility of the restoration from the facial aspect, which is important for maintaining the natural appearance of the tooth. Aesthetic considerations are particularly significant in anterior teeth, where the visibility of restorations can impact the overall smile and facial aesthetics. While retention, outline form, and resistance are important factors in cavity preparation, the lingual approach is specifically chosen to enhance the aesthetic outcome.

Emery is a polishing agent that can be used to polish amalgam restorations. It is a natural abrasive material that is relatively safe for metal surfaces and does not cause significant wear on the amalgam. Garnet, silex, and alumina are also abrasive materials, but they are less commonly used for polishing amalgam due to potential issues with scratching or wearing down the restoration.

Explanation: In Class III composite preparations, retention points should be placed entirely in dentin. This is because dentin provides a more reliable substrate for bonding compared to enamel, especially in areas where the enamel may be thin or compromised. By placing retention points in dentin, the restoration can achieve better mechanical retention and bonding strength, which is crucial for the longevity of the restoration.

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.