DENTIN PERMEABILITY AND TRACER TESTS

Objectives: This paper reviews the evidence for dentine's permeability in order to clarify and emphasize its confounding effect on leakage t est measurements, and hence the need to use special test designs to av oid its effects. Methods: The literature on the subject between 1887 a nd 1997, including 249 articles. Conclusions: The prerequisite conditi on for any tracer penetration test is that unflawed specimens are them selves impermeable to tracer. Entry of tracer then can be used to indi cate correctly the location or severity of flaws. The relative imperme ability of intact dental enamel permits such testing of the enamel-res toration interface seal, but the same is not true when using dentine, which is usually frankly porous to most tracers through its tubules. F alse positive results are very likely. Recent intense interest in dent ine bonding agents has increased the need and frequency of these tests with dentine, but this serious confounding factor has so far generall y remained unstated, and has only been controlled adequately in one st udy. If tracer penetration test results are to be meaningful, then ade quate control is required. (C) 1998 Elsevier Science Ltd. All rights r eserved.