Adult Atlantic Wolffish, Anarhichas lupus, have a heterodont oral dentition consisting of long caniniform teeth in the symphysial regions of the dentaries and premaxillae and large molariform teeth posteriorly on the dentaries, dermopalatines, and vomer. Teeth are ankylosed to the bone of attachment. Wolffish use the caniniform teeth to capture prey including molluscs, crustaceans, echinoderms, and, less commonly, fishes. Prey are transported posteriorly and crushed between the molariform teeth. The molariform teeth of adults fit closely together despite individually variable shapes and sizes in a space-filling pattern that we term anamestic. Adult wolffish have an unusual tooth replacement pattern in which teeth are lost and subsequently replaced all at once, a pattern called simultaneous replacement. We used dissection, osteology, histology, and micro-computed tomography (CT) to study tooth replacement in a series of Anarhichas lupus from the western North Atlantic. Tooth development is intraosseous, with new tooth germs eroding into a specialized spongy portion of the bone of attachment. Simultaneous replacement involves extensive remodeling of this spongy bone. As planktonic larvae, wolffish have uniformly conical teeth, but relatively soon after settling a heterodont dentition similar to that of adults begins to develop. Juveniles exhibit a striking left-right symmetry of oral teeth and lack the anamestic pattern seen in adults. We compare tooth replacement in Atlantic Wolffish with that of Bluefish, Pomatomus saltatrix, another teleost with intraosseus tooth replacement. Patterns of intraosseous replacement in these taxa represent different evolutionary solutions to different ecological conditions, particularly diets. Not all teleosts with intraosseous tooth development are heterodont, but we predict that teleosts with heterodont dentitions will have intraosseous tooth development because this offers a way to provide attachment for functional teeth while replacement teeth are developing.