Histological, histochemical, and protein changes after induced malocclusion by occlusion alteration of Wistar rats.

Although disorders of the stomatognathic system are common, the mechanisms involved are unknown. Our objective was to study the changes in the masseter muscles after unilateral exodontia. Molar extraction was performed on Wistar rats (left side), and the animals were sacrificed after either 14 or 26 days. The masseter muscle was processed for histological analysis, conventional and in situ zymography, and immunohistochemistry. The morphological analysis showed unique and specific characteristics for the experimental group. By conventional zymography no significant values of 72 kDa MMP-2 (P < 0.05) were found in both of the sides of masseter muscle after 14 and 26 days of unilateral extraction. The in situ zymography showed gelatinolytic activity on all deep masseter muscles, with significant increase on the contralateral side after 14 and 26 days (P < 0.05). The immunohistochemistry demonstrated greater expression of MMP-2 than MMP-9 and MMP-14 in all masseter muscles and there were few differences in the staining of 4 TIMPs. This knowledge about morphology and molecular masticatory muscle remodeling following environmental interventions can be used to develop clinically successful treatments.

Reduced bone and body mass in young male rats exposed to lead.

The aim of this study was to see whether there would be differences in whole blood versus tibia lead concentrations over time in growing rats prenatally. Lead was given in the drinking water at 30 mg/L from the time the dams were pregnant until offspring was 28- or 60-day-old. Concentrations of lead were measured in whole blood and in tibia after 28 (28D) and 60 days (60D) in control (C) and in lead-exposed animals (Pb). Lead measurements were made by GF-AAS. There was no significant difference (P > 0.05) in the concentration of whole blood lead between Pb-28D (8.0 ± 1.1 µg/dL) and Pb-60D (7.2 ± 0.89 µg/dL), while both significantly varied (P < 0.01) from controls (0.2 µg/dL). Bone lead concentrations significantly varied between the Pb-28D (8.02 ± 1.12 µg/g) and the Pb-60D (43.3 ± 13.26 µg/g) lead-exposed groups (P < 0.01), while those exposed groups were also significantly higher (P < 0.0001) than the 28D and 60D control groups (Pb < 1 µg/g). The Pb-60D group showed a 25% decrease in tibia mass as compared to the respective control. The five times higher amount of lead found in the bone of older animals (Pb-60D versus Pb-28D), which reinforces the importance of using bone lead as an exposure biomarker.

Biomarcadores de exposição a chumbo / Biomarkers of exposure to lead

O objetivo deste artigo é descrever alguns dos principais biomarcadores de exposição a chumbo, mostrando suas vantagens e limitações, assim como sua relação com exposição presente, passada ou cumulativa. Essas noções básicas são fundamentais para a compreensão dos efeitos do chumbo, da dificuldade do diagnóstico e do problema da exposição a baixas doses. Os biomarcadores de exposição a chumbo mais discutidos neste artigo são sangue, osso e dentes.

This article aims at describing some of the most important biomarkers of exposure to lead, showing its advantages and limitations, as well as how they relate to present, past or cumulative exposure to lead. This basic knowledge is essential for the comprehension of the effects of lead, the difficulties of the diagnosis of excessive exposure, and the problem of exposure to low levels of lead. The biomarkers of exposure discussed in depth in this article are blood, bone, and teeth.

Tooth pigmentation caused by bilirubin: a case report and histological evaluation.

Systemic disorders in pediatric patients, such as congenital biliary atresia, acute liver failure, and biliary hypoplasia, may be the indications for a need of liver transplantation. One of the manifestations of these disorders is the elevated serum levels of bilirubin (hyperbiliru-binemia), a product of hemoglobin degradation, which is deposited in different tissues, including mineralized and soft tissues. When hyperbilirubinemia occurs during the period of dental development, these teeth can develop a green coloration, which remains permanently, because, after maturation, these tissues loose their metabolic activity. This case report describes a 9-year-old girl who required a liver transplant due to biliary atresia when she was three years old. Some of her pigmented teeth needed extraction and afterwards were submitted for histological analysis and compared with sound teeth.