Comparative studies of demarcated hypomineralised lesions of dental enamel and their fluorescence properties

Abstract

Demarcated hypomineralised lesions (DHL) of dental enamel are qualitative developmental defects including molar-incisor hypomineralisation (MIH), hypomineralised second primary molars (HSPM) as well as other demarcated opacities of systemic origin. Many epidemiological studies have failed to determine the causative factors associated with these defects; therefore, primary prevention is implausible at this stage. A growing interest in the exploration of DHL structural and clinical characteristics has developed over the past decade.

Several DHL characteristics such as ionic and protein content, hardness and modulus of elasticity along with the mineral density of hypomineralised molars have been investigated in in vitro studies. However, validation of other methods that can possibly detect and quantify DHL in in vivo clinical settings would be beneficial to predict the progression and outcome of the lesions. One alternative could be fluorescence techniques currently used to detect and quantify carious lesions, which could be used as a surrogate method to quantify the mineral content clinically.

The detrimental structural characteristics of DHL predispose affected teeth to suffer post-eruptive breakdown facilitating carious lesion development, particularly in the presence of unfavourable oral health conditions. However, limited research of the impact of DHL on dental caries prevalence, severity and sequelae in different caries- risk communities exist. Severe carious lesions associated with DHL could bring a significant financial burden to the children, families and health authorities. These costs could be reduced if oral health care practitioners (OHCPs), particularly those working in the public sector, manage and treat DHL-affected children correctly. Nevertheless, public OHCPs’ knowledge and experience with regard to DHL are undetermined.

The present research project has three main aims: 1) to assess the knowledge, experience and perceptions of Australian and Chilean OHCPs working in the public sector about MIH, 2) to investigate the impact of DHL on the dental caries prevalence, severity and sequelae in schoolchildren from two communities with different caries experience (Melbourne, Australia and Talca, Chile) and 3) to explorethe optical fluorescence in DHL with two clinical fluorescence techniques (QLF-D and SOPROlife®).

Results highlighted that MIH is a prevalent condition encountered by OHCPs in Australian and Chilean public dental clinics (88.6%). Chilean OHCPs presented lower knowledge scores and confidence - when diagnosing and treating MIH affected children - than Australian participants.

The prevalence of DHL (25%), MIH (15%) and HSPM (6%) did not vary between countries and the clinical characteristics of defects were similar to previous reports. Approximately one in five children had severe carious lesions and the majority of them had one or more teeth with pulpal involvement. Statistical analysis demonstrated that severely DHL-affected teeth in Chilean children were more likely (OR = 2.87) to be untreated compared to Australians. Ordinal regression indicated that DHL-affected children (OR = 2.17) and Chileans (OR 1.84) had an increased likelihood of having severe carious lesions compared to non-affected children and Australian participants, respectively.

The analyses of fluorescence methods indicated that QLF-D is a useful method to detect hypomineralised lesions of different clinical presentation, with red fluorescence putatively related to the severity of the defects. On the other hand, SOPROlife® demonstrated large areas of light reflectance that influenced the repeatability of the measures. Both tested fluorescence methods detected DHL, but did not quantify accurately.