Final answer:
An appropriate Class II amalgam restoration for primary molars should include an axial wall that follows the shape of the dentino-enamel junction, without excessive occlusal divergence or creating an isthmus that's too large, and may involve undercuts for mechanical retention.
Step-by-step explanation:
A preparation for a Class II amalgam restoration in primary molars should include an axial wall that parallels the dentino-enamel junction. The details of the tooth structure play a critical role in dental restorations. In the tooth, the crown is the visible part above the gum line, covered with enamel, which is the hardest substance in the body. Beneath that, the dentin provides a layer of protection around the pulp cavity, where the pulp houses nerves and blood vessels. For primary molars, ensuring that restorations like amalgam fillings are done correctly involves precise shaping of the cavity walls. It is not recommended to have occlusally divergent walls or an isthmus that is too large, as this can weaken the tooth structure. Moreover, creating undercut enamel and dentin is a technique used to provide mechanical retention for the amalgam, though it must be done with care.