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.L’examen morpho-pathologique de sillons surnuméraires a donné les résultats suivants:1. En coupes transversales observées en microscopie classique, les sillons surnuméraires apparaissent peu profonds, en forme d’assiette ou de coupe. Dans certains, on trouve un contenu, non encore décrit dans la littérature et dont la structure n’apparaît pas nettement en microscopie classique. On trouve ce contenu dans 22% des sillons surnuméraires étudiés.2. Etudié en microscopie électronique à transmission, le contenu des sillons surnuméraires apparaît fait d’émail. Les mesures de dureté indiquent pour cet émail des valeurs inférieures d’un tiers à celles de l’émail normal. La microradiographie montre que cet émail est, en général, beaucoup moins radiodense que l’émail normal.3. Etant donné que le contenu des sillons surnuméraires s’est révélé être un émail de faible dureté et de faible radiodensité, on peut considérer que, par ses propriétés tissulaires, cet émail est sensible à l’attaque carieuse. Cette hypothèse est corroborée par les résultats de l’étude des sites carieux dans les sillons surnuméraires

On the size of apical foramen in anterior teeth, bicuspids and molars

The present authors have used a replica method to obtain area size measurements for the apical foramen in 4,613 human permanent teeth, and have obtained the following results:1. The morphology of the apical foramen is rich in variety which make it difficult to express its accurate size using foramen diameter measurement. It is therefore more appropriate to determine its size as an area measurement.2. Much variation was observed in the size of the apical foramen even for teeth of the same type. It was, however, also observed that the foramen is smaller in smaller types of teeth and larger in larger types of teeth. It was also observed that, in teeth of the same type, those with a greater number of roots have smaller foramen than those with a smaller number of roots.Les auteurs ont utilisé la méthode des répliques pour mesurer la surface des foramen apicaux de 4.613 dents humaines définitives. Les résultats obtenus ont été les suivants:1. La morphologie du foramen apical est à ce point variée qu’il est difficile d’exprimer sa taille précise en mesurant le diamètre du foramen. De ce fait il est préférable de déterminer sa dimension par une mesure de surface.2. Un grand nombre de variations ont même été observées dans la dimension du foramen apical pour les dents du même type. Cependant, il a été aussi observé que le foramen est plus petit dans les dents de type petit et plus larges dans les dents de grand type. Il a été constaté également que dans les dents de même type, celles comptant un plus grand nombre de racines possèdent des foramen plus petits que ceux des dents dont les racines sont moins nombreuses

Histology of tbe fissure contents in completely impacted teeth

Nous avons étudié les fissures occlusales et leur contenu au niveau de dents complètement incluses à l’aide du microscope optique et électronique et obtenu quelques résultats intéressants. C’est-à-dire au microscope optique, l’examen des coupes de fissures ont montré:a) Un certain nombre de fissures étaient comblées.b) D’autres étaient comblées à certains endroits limités, localisés le long des murs de la fissure.c) D’autres enfin ne contenaient rien et les fissures étaient pratiquement vides.La fine structure du contenu des fissures ne pouvait pas être précisée au microscope optique et l’interprétation ne peut qu’être subjective.Observés au microscope électronique, les dépôts comblant les fissures se sont avérés être de l’émail hypominéralisé

Pits and fissures: etch resistance in prismless enamel walls

The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included.Background: In a previous study to examine the nature of etching on the walls of fissures, there was a consistent result of resistance to deep etching on parts of the walls and a zone of lesser etching on part of the walls as evidenced by the uptake of stain. The staining had been used to examine the nature of the etch pattern. The aims of this study were to define the nature of this etch resistant area. Methods: A sample of 55 teeth, both molars and premolars, were divided into three groups. In the first group the wetting of fissures by the etchant was examined; the second group tested for the effects of pellicle-cuticle-debris or air entrapment on the etching process. The final group looked at alternative mechanical treatments of the fissure prior to etching. Results: The specimens split along the fissures showed clearly that the etch resistant zone was not due to lack of contact with the etchant or the presence of a pellicle-cuticle-debris covering, but to the presence of a prismless enamel structure. This study showed that this zone inhibited tag development on the fissure walls. Conclusions: The mechanical removal of this prismless layer of enamel within the fissure system should result in an improved bonding of a fissure sealant through better tag development, in turn leading to a reduction in the failure rate of a sealant used to prevent caries.MF Burrow, JF Burrow and OF Makinso

TRPC5 ion channel permeation promotes weight gain in hypercholesterolaemic mice

Transient Receptor Potential Canonical 5 (TRPC5) is a subunit of a Ca2+-permeable non-selective cationic channel which negatively regulates adiponectin but not leptin in mice fed chow diet. Adiponectin is a major anti-inflammatory mediator and so we hypothesized an effect of TRPC5 on the inflammatory condition of atherosclerosis. Atherosclerosis was studied in aorta of ApoE−/− mice fed western-style diet. Inhibition of TRPC5 ion permeation was achieved by conditional transgenic expression of a dominant negative ion pore mutant of TRPC5 (DNT5). Gene expression analysis in adipose tissue suggested that DNT5 increases transcript expression for adiponectin while decreasing transcript expression of the inflammatory mediator Tnfα and potentially decreasing Il6, Il1β and Ccl2. Despite these differences there was mild or no reduction in plaque coverage in the aorta. Unexpectedly DNT5 caused highly significant reduction in body weight gain and reduced adipocyte size after 6 and 12 weeks of western-style diet. Steatosis and circulating lipids were unaffected but mild effects on regulators of lipogenesis could not be excluded, as indicated by small reductions in the expression of Srebp1c, Acaca, Scd1. The data suggest that TRPC5 ion channel permeation has little or no effect on atherosclerosis or steatosis but an unexpected major effect on weight gain

Variants of the adenomatoid odontogenic tumor with a note on tumor origin

Three rare variants of the adenomatoid odontogenic tumor (AOT) are described. A follicular AOT associated with an impacted and displaced 28, an extrafollicular variant mimicking a radicular cyst around the apex of 23 and a peripheral (epulis-like) variant exhibiting a periodontal bone defect palatal to 21. On reappraisal of the origin and pathogenesis of the AOT, it would seem that this tumor or hamartomatous lesion is derived from odontogenic epithelium of the dental lamina complex or its remnants.link_to_subscribed_fulltex