Apexification/methods; Blood Platelets/physiology; Dental Pulp Cavity/drug effects; Fibrin/therapeutic use; Tooth Apex/drug effects; Aluminum Compounds/therapeutic use; Animals; Bicuspid/drug effects; Bicuspid/pathology; Calcification, Physiologic/drug effects; Calcium Compounds/therapeutic use; Connective Tissue/drug effects; Connective Tissue/pathology; Dental Pulp Cavity/growth & development; Dental Pulp Cavity/pathology; Dentin/drug effects; Dentin, Secondary/drug effects; Dentin, Secondary/pathology; Dogs; Drug Combinations; Glass Ionomer Cements/chemistry; Male; Oxides/therapeutic use; Regeneration/drug effects; Root Canal Filling Materials/therapeutic use; Root Canal Irrigants/therapeutic use; Root Canal Preparation/methods; Silicates/therapeutic use; Therapeutic Irrigation/methods; Tooth Apex/growth & development; Tooth Apex/pathology