42 research outputs found
Patho-morphological study of the supplemental groove
The following results have been obtained in consequence of patho-morphological examination regarding the supplemental groove.1. Light microscopic observation of cross-sectioned supplemental grooves revealed that most of them were shallow in the form of plate or bowl. Some of the supplemental grooves had contents not described in the past and the structure of the contents was not clear under a light microscope. The contents were found in 22% of the supplemental grooves examined.2. The contents in supplemental grooves which were confirmed under a light microscope were found to consist of enamel itself when examined by means of an electron microscope. Microhardness measurements of this enamel showed less than one third the values of normal enamel. By means of microradiography, it was established that radiolucency of this enamel was, for the most part, much higher than normal enamel.3. It was ascertained that enamel with low hardness and high radiolucency constitutes the contents of supplemental grooves. Judging from its tissue properties, the contents were believed to be susceptible to attack by caries. This view was supported by the results of an investigation of caries sites in supplemental grooves.Lâexamen morpho-pathologique de sillons surnumĂ©raires a donnĂ© les rĂ©sultats suivants:1. En coupes transversales observĂ©es en microscopie classique, les sillons surnumĂ©raires apparaissent peu profonds, en forme dâassiette ou de coupe. Dans certains, on trouve un contenu, non encore dĂ©crit dans la littĂ©rature et dont la structure nâapparaĂźt pas nettement en microscopie classique. On trouve ce contenu dans 22% des sillons surnumĂ©raires Ă©tudiĂ©s.2. EtudiĂ© en microscopie Ă©lectronique Ă transmission, le contenu des sillons surnumĂ©raires apparaĂźt fait dâĂ©mail. Les mesures de duretĂ© indiquent pour cet Ă©mail des valeurs infĂ©rieures dâun tiers Ă celles de lâĂ©mail normal. La microradiographie montre que cet Ă©mail est, en gĂ©nĂ©ral, beaucoup moins radiodense que lâĂ©mail normal.3. Etant donnĂ© que le contenu des sillons surnumĂ©raires sâest rĂ©vĂ©lĂ© ĂȘtre un Ă©mail de faible duretĂ© et de faible radiodensitĂ©, on peut considĂ©rer que, par ses propriĂ©tĂ©s tissulaires, cet Ă©mail est sensible Ă lâattaque carieuse. Cette hypothĂšse est corroborĂ©e par les rĂ©sultats de lâĂ©tude des sites carieux dans les sillons surnumĂ©raires