IADR Abstract Archives
Physiologic Tooth Resorption in Snakes: a Unique Odontoclastic Process
Objectives: To determine the origins and directions of odontoclastic activity along the teeth of snakes during physiologic tooth resorption and compare them to those of other reptiles.
Methods: Histological sections of several lizard species from two zoological museum collections (Australia and Canada) were made and stained using Masson’s trichrome, hematoxylin and eosin, or for Tartrate-Resistant Acid Phasphatase (TRAP) to evaluate odontoclast activity around replacing teeth. The species examined included iguanas, venomous and non-venomous snakes, and monitor lizards, representing three different modes of tooth replacement common to reptiles. High-resolution µCT scans were also made of two additional snake species to determine if non-invasive scans could aid in visualizing the origins and directions of dentine resorption during the snake tooth replacement cycle.
Results: TRAP staining of corn snake (Pantherophis guttatus) sections revealed that, unlike other reptiles, physiologic tooth resorption is initiated within the pulps of functional teeth at a relatively early stage in the life cycle of a tooth. Odontoclasts displace degenerating odontoblasts and transform the pulp-dentine complex from a matrix-secreting region into a resorptive one without any prior signs of external root resorption. Comparative sections and CT scans of other snake species confirm this internal resorptive mechanism is found across snake species. All other reptiles show initial resorption along the cementum of the tooth root, followed by an eventual breach of the dental pulp, and subsequent infiltration by odontoclasts.
Conclusions: Snakes are unique in that tooth resorption is initiated independently from the pressures of an advancing replacement tooth, unlike traditional models for physiologic tooth replacement in other reptiles and even mammals. Snakes have evolved a unique tooth resorption pathway that enables teeth to be replaced without external root resorption until immediately prior to tooth exfoliation.
Methods: Histological sections of several lizard species from two zoological museum collections (Australia and Canada) were made and stained using Masson’s trichrome, hematoxylin and eosin, or for Tartrate-Resistant Acid Phasphatase (TRAP) to evaluate odontoclast activity around replacing teeth. The species examined included iguanas, venomous and non-venomous snakes, and monitor lizards, representing three different modes of tooth replacement common to reptiles. High-resolution µCT scans were also made of two additional snake species to determine if non-invasive scans could aid in visualizing the origins and directions of dentine resorption during the snake tooth replacement cycle.
Results: TRAP staining of corn snake (Pantherophis guttatus) sections revealed that, unlike other reptiles, physiologic tooth resorption is initiated within the pulps of functional teeth at a relatively early stage in the life cycle of a tooth. Odontoclasts displace degenerating odontoblasts and transform the pulp-dentine complex from a matrix-secreting region into a resorptive one without any prior signs of external root resorption. Comparative sections and CT scans of other snake species confirm this internal resorptive mechanism is found across snake species. All other reptiles show initial resorption along the cementum of the tooth root, followed by an eventual breach of the dental pulp, and subsequent infiltration by odontoclasts.
Conclusions: Snakes are unique in that tooth resorption is initiated independently from the pressures of an advancing replacement tooth, unlike traditional models for physiologic tooth replacement in other reptiles and even mammals. Snakes have evolved a unique tooth resorption pathway that enables teeth to be replaced without external root resorption until immediately prior to tooth exfoliation.