Feline odontoclastic resorptive lesions: unveiling the early lesion

Abstract

The purpose of this study was to increase understanding of the factors initiating feline odontoclastic resorptive lesions (FORLs). Fifty-six teeth (clinically and radiographically unaffected by ORLs) were harvested. Of these, 43 were from cats that had ORLs in other teeth (group A) and 13 were from cats with no clinical or radiographic evidence of ORLs in any teeth (group B). Twenty-six teeth in group A and one tooth in group B showed histological evidence of external root resorption (surface resorption and replacement resorption resulting in ankylosis). Some teeth in group B showed healed cementum resorption. It has previously been assumed that FORLs were similar to lesions associated with peripheral inflammatory root resorption, and were associated with periodontal disease. These histological findings suggest instead that a FORL is a non-inflammatory replacement resorption, resulting in ankylosis. The periodontal ligament of resorbing teeth lacked normal fibrous architecture, but was not inflamed. Resorption was not identified in cervical cementum. However, the histological appearance of the cervical cementum differed between the two groups. Several aetiopathogenetic explanatory models which arise from these observations are discussed.

Update on the Etiology of Tooth Resorption in Domestic Cats

“…These apparently ''healthy'' teeth showed hyperemia, edema, and degeneration of the periodontal ligament, with marked fiber disorientation, increased osteoid formation along alveolar bone surfaces (hyperosteoidosis), gradual narrowing of the periodontal space, and areas of ankylotic fusion between the tooth and alveolar bone (Fig. 3) [25]. These findings demonstrate events that occur before resorption and suggest that the early FORL may be noninflammatory in nature [25].…”

“…3) [25]. These findings demonstrate events that occur before resorption and suggest that the early FORL may be noninflammatory in nature [25]. Ankylosed roots are at risk of being incorporated into the normal process of bone remodeling, and the tooth substance is gradually resorbed and replaced by bone (replacement resorption) (Fig.…”

“…5), whereas an abnormal thickening of acellular cementum can be found on cervical root surfaces (Fig. 6) [25]. In other species, hypercementosis has been observed in unerupted, hypofunctional, and extruding teeth without opposing antagonists [27][28][29][30] and in certain conditions, such as hyperthyroidism [31], hyperpituitarism [32][33][34], Paget's disease [35][36][37], and vitamin A deficiency [38,39].…”

Human and Feline Invasive Cervical Resorptions: The Missing Link?—Presentation of Four Cases

“…Interestingly, the clinical, radiologic, and histopathologic features of ICR and FORL appear to be analogous (21)(22)(23). It seems unlikely that the pathogenesis of ICR in humans and of FORL in the feline population, respectively, would be substantially different.…”

An NMR- and MS-based metabonomic investigation of saliva metabolic changes in feline odontoclastic resorptive lesions (FORL)-diseased cats

“…A sub-set of affected cats do not show any obvious symptoms but are in pain at the late stage, which will be revealed with jaw spasm when FORL teeth are probed with dental instruments, even under general anesthesia. Unlike cavities in humans, which are the result of bacterial enzymes and acids digesting the teeth, the etiology of FORL is unknown (Gorrel and Larsson, 2002). Theories supporting an autoimmune response mediating cellular and humoral factors, viral infection, mechanical trauma, metabolic imbalances relating to calcium regulation, and dietary factors have all been proposed (Reiter and Mendoza, 2002;Lommer and Verstraete, 2003).…”