Advances in in vitro testing techniques for dentine hypersensitivity

Dentine hypersensitivity (DH) is a common clinical condition that is responsible for pain and/or discomfort in response to various stimuli – typically thermal, tactile, osmotic or chemical – not ascribed to any other tooth or oral disease (Chap. 1). The frequent use of acidic beverage and foods is considered one of the typical conditions improving discomfort and pain. Moreover, restorative procedures including periodontal therapy and hygienic professional procedures may also induce mild-to-moderate discomfort that require the use of desensitising products to reduce and remove the symptoms. It was also evident from both prevalence studies and clinical practice that DH was identified in two population groups, namely, those individuals with good oral hygiene and those with periodontal disease (or DH following periodontal therapy) (see Chaps. 1, 3 and 4). As a result of recent changes in the definitions of DH and root sensitivity (RS), we may discuss DH in the following manner: (1) a <Emphasis Type=–Italic—>primary</Emphasis> dentine hypersensitivity (DH) when (cervical) dentine surface is exposed as a consequence of enamel erosion and abrasion and after appearance of gingival recession and retraction and (2) a <Emphasis Type=–Italic—>secondary</Emphasis> dentine hypersensitivity (RS) when certain clinical periodontal procedures have been performed and the root surface has been altered with possible smear layer removal, thereby exposing a number of dentine tubules to the oral cavity (see Chap. 1). The main purpose of this chapter therefore is to review and discuss the recommended in vitro testing techniques in order to evaluate the morphological aspect of both primary and secondary DH (and some aspects of the so-called supersensitive dentine as suggested by Pashley 2013) and to test in vitro the efficacy of (new) products designed to reduce DH. The chapter will also discuss the methods currently used in the laboratory in order to detect the reduction of the functional diameter of dentine tubules and the subsequent effect on dentine fluid flow (dentine permeability).