Tooth, Odontoblast - Necrosis

Image of necrosis in the tooth from a female F344/N rat in a subchronic study
Tooth, Odontoblast - Necrosis in a female F344/N rat from a subchronic study. The odontoblasts lining the dorsal tooth pulp are necrotic (arrow).
Figure 1 of 4
Image of necrosis in the tooth from a female F344/N rat in a subchronic study
Tooth, Odontoblast - Necrosis in a female F344/N rat from a subchronic study (higher magnification of Figure 1). The odontoblasts lining the dorsal tooth pulp have eosinophilic cytoplasm and pyknotic nuclei (arrow) indicative of necrosis.
Figure 2 of 4
Image of necrosis in the tooth from a female F344/N rat in a subchronic study
Tooth, Odontoblast - Necrosis in a female F344/N rat from a subchronic study. There are 2 regions with necrotic odontoblasts (arrows).
Figure 3 of 4
Image of necrosis in the tooth from a female F344/N rat in a subchronic study
Tooth, Odontoblast - Necrosis in a female F344/N rat from a subchronic study (higher magnification of Figure 3). The odontoblasts have eosinophilic cytoplasm and pyknotic or faded nuclei (arrow) indicative of necrosis.
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comment:

Odontoblast necrosis is characterized by loss of odontoblasts and odontoblasts with highly eosinophilic cytoplasm and shrunken and/or faded nuclei ( Figure 1image opens in a pop-up window , Figure 2image opens in a pop-up window , Figure 3image opens in a pop-up window , and Figure 4image opens in a pop-up window , arrows). Odontoblast necrosis due to chemical exposure has been observed in NTP studies. The proposed mechanism of necrosis was infarction secondary to thrombosis of pulp vessels. Inflammation in the pulp can also result in ischemic necrosis due to increased pressure in the tooth pulp from tissue swelling within the confines of the dentin, which limits the degree of swelling that can occur. In addition, the development of collateral blood supply within the pulp is limited because blood vessels supplying the pulp must enter the tooth through the apex of the tooth. Inflammation of the tooth pulp with odontoblast necrosis can be an incidental lesion in rodents.

recommendation:

Odontoblast necrosis should be diagnosed and graded based on the extent of the lesion. If the odontoblast necrosis is secondary to thrombosis of vessels in the tooth pulp, necrosis should be diagnosed (as opposed to infarct), and the suspected pathogenesis should be thoroughly discussed in the pathology narrative. Associated inflammation should not be diagnosed separately unless it is severe enough to warrant a separate diagnosis. If the inflammation is the primary lesion and the cause of the odontoblast necrosis, the inflammation should be diagnosed, and the pathologist will need to use his or her judgment in determining whether the odontoblast necrosis should also be diagnosed. If the odontoblast necrosis is not diagnosed, it should be described in the pathology narrative.

references:

Long PH, Leininger JR. 1999. Teeth. In: Pathology of the Mouse (Maronpot RR, ed). Cache River Press, St Louis, MO, 13-28.
Abstract: http://www.cacheriverpress.com/books/pathmouse.htm

Nyska A, Maronpot RR, Long PH, Roycroft JH, Hailey JR, Travlos GS, Ghanayem BI. 1999. Disseminated thrombosis and bone infarction in female rats following inhalation exposure to 2-butoxyethanol. Toxicol Pathol 27:287-294.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/10356705

Zbinden G, Grimm L. 1985. Thrombosis effects of xenobiotics. Arch Toxicol 8(suppl):131-141.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/3006632