Isolated development of inner (wall) caries like lesions in a bacterial-based in vitro model

Abstract

The study conducted in a bacterial-based in vitro caries model aimed to determine whether typical inner secondary caries lesions can be detected at cavity walls of restorations with selected gap widths when the development of outer lesions is inhibited. Sixty bovine tooth specimens were randomly assigned to the following groups: test group 50 (TG50; gap, 50 μm), test group 100 (TG100; gap, 100 μm), test group 250 (TG250; gap, 250 μm) and a control group (CG; gap, 250 μm). The outer tooth surface of the test group specimens was covered with an acidresistant varnish to inhibit the development of an outer caries lesion. After incubation in the caries model, the area of demineralization at the cavity wall was determined by confocal laser scanning microscopy. All test group specimens demonstrated only wall lesions. The CG specimens developed outer and wall lesions. The TG250 specimens showed significantly less wall lesion area compared to the CG (p<0.05). In the test groups, a statistically significant increase (p<0.05) in lesion area could be detected in enamel between TG50 and TG250 and in dentine between TG50 and TG100. In conclusion, the inner wall lesions of secondary caries can develop without the presence of outer lesions and therefore can be regarded as an entity on their own. The extent of independently developed wall lesions increased with gap width in the present setting.

Secondary caries and microleakage

“…Variants are e.g., "inner (wall) caries like lesion" [77] and "secondary caries wall lesion" [78]. Firstly, as argued in a previous section there is a difference between an artificially created "caries-like lesion" characterized by a certain level of demineralization, versus the disease entitled "caries".…”

“…The majority of research papers use the term "wall lesion" simply to describe the portion of a caries lesion or artificially created caries-like lesion that is in contact with a restoration. However, some investigators have also used the term to describe the surface of tooth specimens placed against a block of restorative material and exposed to an acidic environment [77,78].…”

“…They reported also that artificial caries-like lesions could be observed at "gap size zero", although they cautioned about the limitations of the model and need to be careful in drawing clinical implications from their findings. Using the same device, other investigator groups have replicated the geometric setup and consistently described the demineralization occurring on the side of the specimen facing the block of restoration materials and regrettably stuck with the term "wall lesion" [77,78]. E.g., in one of the studies a specimen block was covered with an acid-resistant varnish leaving only one surface, i.e.…”

“…E.g., in one of the studies a specimen block was covered with an acid-resistant varnish leaving only one surface, i.e. "the wall", some 50 to 250 µm away from a block of resin composite and place the assembly in an acidic environment [77]. Obviously, one would expect demineralization to occur, but complete misunderstanding of the results by clinicians because of poor choices of terminology by basic scientists is understandable upon reading conclusions such as: "The extent of independently developed wall lesions increased with gap width in the present setting" [77].…”

Evaluation of Novel Anticaries Adhesive in a Secondary Caries Animal Model

“…Therefore, the Keyes scoring method is still widely used for analyzing the primary dental caries in animal models and was modified for secondary caries in this study along with a demonstration of micro-CT. In addition, secondary caries lesions are thought to be associated with spaces between the tooth tissue and the restorations; this is why a line was chosen which located the side wall of the cavity as the ROI [Diercke et al, 2009;Nassar and Gonzalez-Cabezas, 2011]. …”