Atorvastatin inhibits osteoclastogenesis and arrests tooth movement.

INTRODUCTION: In addition to their cholesterol-lowering effects, the statin class of drugs appears to enhance osteogenesis and suppress bone resorption, which could be a clinical concern during orthodontic treatment. In this animal study, we aimed to determine whether atorvastatin (ATV) affects orthodontic tooth movement (OTM) through osteoclast inhibition. Furthermore, we analyzed the potential adverse effects of ATV on long-bone turnover and endochondral ossification. METHODS: Rats were administered ATV (15 mg/kg) or saline solution via gavage (n = 12 animals/group), starting 2 weeks before initial OTM. Tooth displacement was measured after 7, 14, and 21 days. Histologic sections of the maxilla and femur were obtained after 14 and 21 days of OTM and stained (hematoxylin and eosin; TRAP assay) for histomorphometric analysis. RESULTS: ATV was associated with significant (P <0.05) reductions in OTM and osteoclast counts. Independently of drug administration, OTM increased the number of osteoclasts and reduced the bone-volume ratio compared with the control maxillae without OTM. Long-term statin administration did not appear to affect femoral endochondral ossification. CONCLUSIONS: This experimental study showed that the long-term use of ATV can significantly promote osteoclast inhibition and slow the OTM in the first week in rats. Under physiologic conditions, the drug did not affect bone turnover and endochondral ossification.

Collagenous matrix as a predictor for bone formation: a digital technique for collagen quantification

The collagenous matrix plays a fundamental role in the process of bone regeneration, so it is essential to study how it is primarily formed in situations in which critical bone defects are created. Objective: this study seeks to quantify the collagenous matrix formed in critical bone defects in the calvaria of mice over the process of bone regeneration promoted by the association of poly(lactide-co-glycolide) (PLGA) porous scaffolds and stem cells from deciduous teeth (SCDT). In addition, this study attempted to establish a precise protocol for the digital quantification of collagen through a histological method. Materials and method: Nine Wistar rats were used, in which critical defects of 8.0 mm of diameter were made in their calvarium. The animals were divided into three groups (n = 9): I ­ PLGA scaffolds; II ­ PLGA scaffolds/SCDT; III ­ PLGA scaffolds/SCDT maintained in osteogenic medium for 13 days. Within sixty postoperative days, calvaria were removed for histometric analysis following a digital protocol. A specific digital analysis method was designed for this study, in which a more precise quantification and differentiation between collagen fibers and non-collagenous tissue was possible, excluding factors that would normally alter the results. Results: it was noted that the association of PLGA scaffolds and SCDT maintained in osteogenic medium resulted in collagen matrix formation statistically higher than the other groups (p<0.05). Conclusion: the protocol designed for collagen quantification was precise and efficient, producing methodologically standardized results.

Long- and short-term diabetes mellitus type 1 modify young and elder rat salivary glands morphology.

OBJECTIVE: In this study we performed a temporal analysis of the effects of Diabetes Mellitus on morphology and laminin deposition in salivary glands of young (2 months-old) and aging (12 months-old) male Wistar rats, using immunohistochemistry. MATERIALS AND METHODS: The animals were divided in control and diabetic (Streptozotocin induced) groups and euthanized after short and long-term diabetes induction. RESULTS: Short-term induction led to vacuolization of parotid acinar cells and increased laminin deposition in both animal ages. In young rats, no difference was observed between short or long-term diabetes regarding laminin deposition, but parotid acinar cells vacuolization was more discrete after long-term diabetes. A slight decrease of submandibular gland convoluted granular ducts was observed in young and elder diabetic animal ages. In diabetic aging rats was observed an increase of laminin content only in the parotid gland. CONCLUSIONS: These results suggest that some Diabetes Mellitus effects on salivary glands are not progressive over time, possibly due to the existence of adaptive mechanisms in response to chronic hyperglycemia. They also show that the duration of the disease was more relevant to the morphological effects than the age, although it is known that aging per se affects salivary gland morphology and function.

X-ray irradiation alters the actin cytoskeleton in murine lacrimal glands.

OBJECTIVE: The aim of this study was to evaluate the effects of X radiation on the distribution of filamentous actin (F-actin) in the mouse exorbital lacrimal gland. MATERIALS AND METHODS: Mice were divided into groups that received no radiation (n = 6) or one single exposure of 36 mGy of X radiation (n = 12). The animals were sacrificed after 4, 8 or 24 h. The lacrimal glands were stained with Hematoxylin/Eosin or Rhodamine-phalloidin and the filamentous actin arrangement was analyzed by confocal microscopy. RESULTS: After 4 h of X-ray exposure there was an apparent increase in acini area and a decrease in the cortical F-actin content in secretory cells. This effect decreased gradually over time, returning to values close to the control after 24 h. CONCLUSION: This study shows that a 36 mGy diagnostic X-ray dose affected reversibly the mouse exorbital lacrimal gland, suggesting that radiation used in diagnosis may induce changes on cell morphology due to actin remodeling.

Chronic alcohol consumption promotes alterations on salivary gland regeneration process.

The aim of this study is to investigate the histological effect of alcohol ingestion on the regeneration of the submandibular gland (SMG) in rats. Twelve 60-day-old male Wistar rats were randomized into two experimental groups. Test group (TG) animals ingested 40° GL of alcohol for 45 days before surgery, being its concentration gradually increased 10° GL/week for 4 weeks to achieve the final concentration of 40° GL. The control group (CG) received water during the whole experimental period. One-third of the left SMG lobe was removed. Three and seven days after, the whole gland was excised and analyzed. In the TG, the inflammatory process was pronounced when comparing the CG on day 3. The inverse aspect was observed on day 7, associated with an advanced parenchyma development. Changes in laminin expression and glycoproteins production were observed in the TG, causing advanced morphogenesis and delay in cytodifferentiation during the salivary gland regeneration, probably due to alcohol effects. Animals who received ethanol showed alterations in the pattern of glandular regeneration.

Histologic evaluation and immunohistochemical localization of STRO-1 and BMP-4 in rat immature teeth: a comparison between vital and induced pulp necrosis.

OBJECTIVE: To assess histological features and the expression of STRO-1 and BMP-4 in dental pulp and periapical tissues in vital or necrotic rat immature teeth. DESIGN: The lower left first molars of male Wistar rats ageing four weeks (n=24) had their pulps exposed to the oral environment for 3, 6, 9 and 12 weeks (animals ageing 7, 10, 13 and 16 weeks-old, respectively; n=24). The right lower first molars served as control untouched teeth. After sample harvesting the jaws were dissected and processed for histology and immunodetection of STRO-1 and BMP-4. RESULTS: Necrotic teeth had root development arrested, while control animals showed development of dental tissues. Immunohistochemistry showed that detection of BMP-4 was restricted to vital pulps. For both groups, STRO-1 expression was evident around blood vessels walls. Neither BMP-4 nor STRO-1 was observed in the apical papilla region. CONCLUSION: STRO-1-positive precursor cells were not detected in the apical papilla. BMP-4 expression has not been detected during infection.

Tooth supported prosthetic rehabilitation in a 5-year-old child with early childhood caries.

This paper reports the case of a 5-year-old patient with early childhood caries (ECC) and presents an alternative prosthetic treatment with a tooth-supported overdenture. Primary canines were endodontically treated and received intraradicular posts with ball-type attachments to attach a tooth-supported overdenture. The patient was followed for 18 months both clinically and radiographically. In addition to esthetic and functional oral rehabilitation, the prosthetic treatment had an important psychological impact on recovery of patient's self-esteem.

Comparative analysis of two fixating and two decalcifying solutions for processing of human primary teeth with inactive dentin carious lesion

O objetivo deste estudo foi analisar qualitativamente a preservação das características teciduais pulpares de dentes decíduos ântero-superiores humanos com lesão cariosa de natureza inativa em dentina, comparando-se duas soluções fixadoras (paraformaldeído a 4% e formalina a 10%, ambos com tampão fosfato 0,1 M) e descalcificadoras [ácido fórmico/citrato de sódio – solução de Ana Morse e EDTA (ácido etileno diamino tetracético) a 10%]. Oito dentes foram subdivididos em 4 grupos (n = 2), variando-se o agente fixador e descalcificador. Grupo 1: paraformaldeído a 4% e solução de Ana Morse; Grupo 2: formalina a 10% e solução de Ana Morse; Grupo 3: paraformaldeído a 4% e EDTA a 10%; Grupo 4: formalina a 10% e EDTA a 10%. Os dentes foram fixados e posteriormente descalcificados até que uma consistência borrachóide fosse obtida. Cortes histológicos de 6μm de espessura foram corados com hematoxilina e eosina (H&E). A fixação com ambas as soluções demonstrou boa conservação tecidual, enquanto que a descalcificação com a solução de Ana Morse pareceu mais adequada, por requerer um menor tempo de processamento das amostras e promover uma melhor preservação dos componentes celulares e da matriz extracelular do tecido pulpar. O EDTA, além de exigir um tempo mais longo de processamento das peças, alterou as características morfológicas da polpa. A combinação formol a 10% – solução de Ana Morse pareceu ser favorável para a metodologia deste estudo.

Vascular endothelial growth factor and its relationship with the dental pulp.

The dental pulp is a loose connective tissue located within rigid dentinal walls. Therefore, when subjected to a stimulus, the pulpal tissue has little expansion capacity. The defense mechanisms of this tissue include the formation of tertiary dentin as well as the production of signaling molecules that help in the repair. The dentin matrix is rich in growth factors (GFs) that, when diluted and diffused into the pulp tissue, aid the healing process of the dentinopulpar complex. The angiogenic GFs participate in this event. Vascular endothelial growth factor (VEGF), a potent mitogen for endothelial cells, promotes endothelial cell survival and angiogenesis. Among its receptors, VEGFR-2 seems to be the most intimately associated with mitogenic activities, cell migration, vascular permeability, and survival of endothelial cells. This literature review addresses the cell-signaling process that occurs in response to a pulp stimulus up to its transduction in the target cell, describing the VEGF, as well as its characteristics and receptors. The reported studies have correlated the expression of VEGF and its potential functions that may have an impact on several dental specialties, thus indicating that further clinical investigations should be conducted in order to translate the results obtained until this moment primarily in laboratory experiments.

Estudo comparativo da morfologia da polpa dentária de dentes humanos submetidos à técnica de clivagem e a técnicas de descalcificação química / Comparative study of dental pulp morphology from human teeth submitted to cutting technique or chemistry decalcification technique

Os rápidos avanços do conhecimento acerca do reparo e regeneração tecidual, têm despertado o interesse pela biologia pulpar. Entretanto, para avaliar microscopicamente a dinâmica do tecido pulpar, é necessário, inicialmente, que o dente seja submetido aos processamentos histológicos de fixação e descalcificação. A descalcificação pode afetar o grau de coloração e pode causar desnaturação de proteínas. Além disso, é um processo demorado, visto que o dente requer um longo período de desmineralização. Assim, a proposta deste trabalho foi de avaliar qualitativamente a matriz extracelular e as células da polpa dentária, comparando três grupos: dois em que o tecido dentário foi descalcificado e um em que a polpa foi removida dos tecidos duros, não necessitando do processo de descalcificação. Dez pré-molares foram fixados em formalina tamponada a 10% por 24 horas. Após, estes dentes foram divididos em três grupos: 4 dentes foram submetidos a processo de descalcificação por meio de solução de Morse, 3 por meio de solução de EDTA a 10% e; os 3 dentes restantes tiveram sua polpa separada dos tecidos duros dentários por meio da técnica de clivagem. Na seqüência, os três grupos foram processados por meio da técnica histológica de rotina e foram corados com H/E. Os resultados desta análise demonstraram que houve uma melhor conservação tanto da matriz extracelular, quanto das estruturas celulares no grupo da clivagem, seguido do grupo Morse e por fim, com a menor conservação das estruturas pelo grupo EDTA.

The rapid advances of the knowledge of repair and regeneration tissues had proved to be an exciting time for pulp biology. However, to study the dynamic of pulp tissue, it is necessary, initially, that the tooth be submitted to histological fixation and decalcification processing. Decalcification may affect the degree of staining and it may cause denaturation of proteins. Furthermore, it is a slow process, demanding long demineralization times for a tooth. Thus, the purpose of the present study was to compare, qualitatively, the pulp extracellular matrix and the pulp cells, submitted to different techniques: EDTA solution decalcification, Anna Morse solution decalcification and a last group which pulp was removed from tooth without decalcification. Ten premolar teeth were fixed in 10% buffered formalin for 24 hours. After this, the teeth were divided in three groups: 4 teeth underwent decalcification with Morse solution; 3, decalcification with 10% EDTA solution and; 3, were sectioned and their pulps were gently removed. Subsequently, the groups followed the routine histological technique and staining with H/E. The results demonstrated that both conservation of pulp cells and extracellular matrix were better in the group without decalcification, followed by the Morse group and, the last, with the worst structures conservation for the EDTA group.

A estrutura da dentina do dente decíduo e sua importâcia clínica / The dentin structure of the teeth deciduous and its clinical importance

Os autores fazem rápida revisäo bibliográfica a respeito da formaçäo e estrutura de dentina em geral. Ressaltam o fato de pouco existir na literatura consultada sobre a arquitetura e gênese da dentina decídua, sendo que os poucos trabalhos existentes estabelecem uma analogia entre a polpa e a dentina decídua dos dentes permanentes. Frente aos achados na literatura, analisaram o comportamento da dentina e polpa do dente decíduo no processo dinâmico de desmineralizaçäo/remineralizaçäo, seu comportamento diante dos fenômenos de erosäo/abrasäo e, finalmente junto aos materiais adesivos täo largamente usados atualmente