Correlation between clinical and radiographic severity scores of hypomineralised first permanent molars (FPMs)

Abstract

Abstract Background Molar incisor hypomineralisation (MIH) is a qualitative developmental defect in enamel affecting first permanent molars and, albeit less frequently, also associated with permanent central incisors. The majority of clinicians rely on the clinical examination when diagnosing and planning treatment for these patients. However, it has been recognized that clinical appearance of these teeth may lead to more severe classifications compared to the radiographic image. Moreover, there are no radiographic standards to which clinicians may rely on to make informed decisions on the prognosis of hypomineralised molars. Objective The aim of this study is to compare macroscopic clinical scores of severity in hypomineralised FPMs to severity scores attributed from radiographs of the same teeth, in order to help the practitioner to make informed judgements about prognosis of these elements and ultimately, help to “save the sixes”. Material and methods Fifty-seven extracted human permanent molars, presenting different severity of hypomineralisation defects were collected during GA services at Guy’s and St. Thomas NHS Trust. Conventional radiographic images where be obtained from each specimen, using a digital radiographic sensor (Heliodent Plus, Sirona), operated at 70kV, 7mA and a 0.06s exposure time. Macroscopic images of the occlusal, buccal, lingual/palatal, mesial and distal surfaces were obtained in a stereomicroscope (Wild M3Z Heerbrugg, Switzerland) with magnification and controlled light conditions. The stereomicroscopic images were scored using two different methodologies. The first was the EAPD/DDE criteria, devised for epidemiologic studies (Ghanim et al. 2015) and which consisted in two subcategories, a clinical status, and a lesion extension category. The second clinical scoring system was the Molar Incisor Hypomineralisation Severity Index (Chawla et al. 2008). In addition, the ICDAS radiographic scoring system was used to score the radiographic appearance of the specimens (Pitts & Stamm 2004). Kappa scores were calculated for the inter- and intra-examiner agreement. The intra-examiner kappa scores for the radiographic evaluation, MIH severity index, and for the both EADP scores was 0.812, 0.816, 1.0, and 1.0 respectively. The inter-examiner kappa was 1.00, 0.806, 0.809 and 1.00 respectively. The kappa scores obtained demonstrated almost perfect agreement. Spearman's rank correlation was be used to correlate the radiographic to the clinical scores (MIH severity index and EAPD/DDE index). Results Weak and not statistically significant correlations were found between the clinical and the radiographic scores. The correlation between the radiographic and MIH severity index was Rs=0.092, p=0.49. while for the radiographic and the EAPD score was Rs=0.077, p=0.57 for the clinical status criteria and Rs=0.161, p=0.23 for the lesion extension criteria. Although most of the teeth examined showed severe defects for both MIH Severity Index scores (74%) and EAPD clinical criteria (61.4%), only 14.1% were also classified as presenting severe defects by the radiographic examination. Conclusion The findings of this study revealed no correlation between the severity of the lesion scored by a clinical and radiographic examinations. Hypomineralisation lesions were less severely scored in radiographs compared to the clinical scores. For this reason, it is very important that clinicians consider both clinical and radiographic examination into consideration before deciding upon the prognosis and treatment of hypomineralised permanent molars.