In some examples, a tool for forming a dental restoration comprises a preformed mold body configured to provide a patient-specific, customized fit with at least one tooth to be restored of a patient. The mold body is configured to align with a portion of a surface of the at least one tooth, and is configured to combine with the at least one tooth to define a mold cavity encompassing at least a portion of desired tooth structure of the at least one tooth to be restored of the patient. The portion of desired tooth structure defines a transition from a supragingival surface of the at least one tooth to a subgingival surface of the at least one tooth.