The demineralization resistance and mechanical assessments of different bioactive restorative materials for primary and permanent teeth: an in vitro study.

OBJECTIVES: This article examines the efficacy of two bioactive dental composites in preventing demineralization while preserving their mechanical and physical properties. MATERIALS AND METHODS: The study compares Beautifil Kids and Predicta® Bioactive Bulk-Fill (Predicta) composites with conventional dental composite. Flexural strength and elastic modulus were evaluated using a universal testing machine. A pH-cycling model assessed the composites' ability to prevent dentin demineralization. Color stability and surface roughness were measured using a spectrophotometer and non-contact profilometer, respectively, before and after pH-cycling, brushing simulation, and thermocycling aging. RESULTS: Beautifil Kids exhibited the highest flexural strength and elastic modulus among the materials (p < 0.05). Predicta demonstrated the highest increase in dentin surface microhardness following the pH-cycling model (p < 0.05). All groups showed clinically significant color changes after pH-cycling, with no significant differences between them (p > 0.05). Predicta exhibited greater color change after brushing and increased surface roughness after thermocycling aging (p < 0.05). While Beautifil Kids had higher surface roughness after pH-cycling (p < 0.05). DISCUSSION/CONCLUSION: Bioactive restorative materials with ion-releasing properties demonstrate excellent resistance to demineralization while maintaining mechanical and physical properties comparable to the control group.

Brain imaging findings in children and adolescents with mental disorders: a cross-sectional review.

BACKGROUND: While brain imaging studies of juvenile patients has expanded in recent years to investigate the cerebral neurophysiologic correlates of psychiatric disorders, this research field remains scarce. The aim of the present review was to cluster the main mental disorders according to the differential brain location of the imaging findings recently reported in children and adolescents reports. A second objective was to describe the worldwide distribution and the main directions of the recent magnetic resonance imaging (MRI) and positron tomography (PET) studies in these patients. METHODS: A survey of 423 MRI and PET articles published between 2005 and 2008 was performed. A principal component analysis (PCA), then an activation likelihood estimate (ALE) meta-analysis, were applied on brain regional information retrieved from articles in order to cluster the various disorders with respect to the cerebral structures where alterations were reported. Furthermore, descriptive analysis characterized the literature production. RESULTS: Two hundred and seventy-four articles involving children and adolescent patients were analyzed. Both the PCA and ALE methods clustered, three groups of diagnosed psychiatric disorders, according to the brain structural and functional locations: one group of affective disorders characterized by abnormalities of the frontal-limbic regions; a group of mental disorders with "cognition deficits" mainly related to cortex abnormalities; and one psychomotor condition associated with abnormalities in the basal ganglia. The descriptive analysis indicates a focus on attention deficit hyperactivity disorders and autism spectrum disorders, a general steady rise in the number of annual reports, and lead of US research. CONCLUSION: This cross-sectional review of child and adolescent mental disorders based on neuroimaging findings suggests overlaps of brain locations that allow to cluster the diagnosed disorders into three sets with respectively marked affective, cognitive, and psychomotor phenomenology. Furthermore, the brain imaging research effort was unequally distributed across disorders, and did not reflect their prevalence.

The fine organization of nigro-collicular channels with additional observations of their relationships with acetylcholinesterase in the rat.

The nigro-collicular pathway that links the basal ganglia to the sensorimotor layers of superior colliculus plays a crucial role in promoting orienting behaviors. This connection originating in the pars reticulata and lateralis of the substantia nigra has been shown in rat and cat to be topographically organized. In rat, a functional compartmentalization of the substantia nigra has also been shown reflecting that of the striatum. In light of this, we reinvestigated the topographical arrangement of the nigro-collicular pathway by examining the innervation of each nigral functional zone. We performed small injections of either biocytin or wheatgerm agglutinin conjugated with horseradish peroxidase restricted to identified somatic, visual and auditory nigral zones. Frontally cut sections showed that innervations provided by the three main nigral zones form a mosaic of complementary domains stratified from the stratum opticum to the ventral part of the intermediate collicular layers, with the somatic afferents sandwiched between the visual and the auditory ones. When reconstructed from semi-horizontal sections, nigral innervations organized in the form of a honeycomb-like array composed of 100 cylindrical modules covering three-quarters of the collicular surface. Such a modular architecture is reminiscent of the acetylcholinesterase lattice we previously described in rat intermediate collicular layers. In the enzyme lattice, the surroundings of the cylindrical modules are composed of a mosaic of dense and diffuse enzyme subdomains. Thus, we compared the distribution of the overall nigral projection and of its constituent channels with the acetylcholinesterase lattice. The procedure combined axonal labelling with histochemistry on single sections for acetylcholinesterase activity. The results demonstrate that the overall nigral projection overlaps the acetylcholinesterase lattice and its constituent channels converge with either the dense or the diffuse enzyme subdomains. The stereometric arrangement of the nigro-collicular pathway is suggestive of an architecture promoting the selection of collicular motor programs for different classes of orienting behavior.

Honeycomb-like structure of the intermediate layers of the rat superior colliculus: afferent and efferent connections.

There is increasing evidence that acetylcholinesterase is organised in a lattice-like fashion in the intermediate layers of the mammalian superior colliculus. In a recent study, we described this organisation in rat by showing that it comprises a well formed honeycomb-like lattice with about 100 cylindrical compartments or modules occupying both the intermediate collicular layers. Considering this enzyme domain as a reference marker for comparing the organisation of collicular input-output systems, the present study investigates whether the principal sensori-motor systems in intermediate layers also have honeycomb-like arrangements. In 33 animals, the distributions of afferents (visual from extrastriate cortex; somatic from the primary somatosensory cortex, the trigeminal nucleus and the cervical spinal cord) and efferents (cells of origin of the crossed descending bulbospinal tract and uncrossed pathway to the pontine gray, the ascending system to the medial dorsal thalamus) were examined in a tangential plane following applications of horseradish peroxidase-wheatgerm agglutinin conjugate (used as an anterograde and retrograde tracer). In 22 of the 33 rats, axonal tracing was made within single tangential sections also stained for cholinesterasic activity in order to compare the neuron profiles with the cholinesterasic lattice.The results show that these afferent and efferent systems are also organised in honeycomb-like networks. Moreover, those related to the cortical, trigeminal and some of the spinal afferents are aligned with the cholinesterasic lattice. Likewise most of colliculo-pontine, colliculo-bulbospinal and half of colliculo-diencephalic projecting cells also tend to be in spatial register with the enzyme lattice. This indicates that the honeycomb-like arrangement is a basic architectural plan in the superior colliculus for the organisation of both acetylcholinesterase and major sensori-motor systems for orientation.

Honeycomb-like structure of the intermediate layers of the rat superior colliculus, with additional observations in several other mammals: AChE patterning.

The aim of the present study was to reinvestigate the stereometric pattern of acetylcholinesterase (AChE) activity staining in the intermediate layers of the superior colliculus in several mammalian species. A pioneering study in the cat and the monkey by Graybiel (1978) stressed the regular arrangement of AChE staining in the deep collicular layers. According to her description, made in the frontal plane, the enzyme was arranged in a mediolateral series of patches, the cores of which tended to line up in the longitudinal axis of the structure, so they formed roughly parallel bands. As exhaustive a description as possible of the AChE distribution was undertaken in the rat by compiling observations in the frontal, sagittal, and tangential planes. It emerged that AChE-positive elements are organized in the form of a conspicuous honeycomb-like network that is divided into about 100 rounded compartments, over virtually the full extent of the intermediate layers. The generality of the rat model was then tested in other rodents such as mouse and hamster and also in cat and monkey. For these species we resorted to a single tangential cutting plane, which proved to be more appropriate for disclosing such a modular arrangement. The data revealed that in all species AChE staining followed the same architectural plan and identified the striking similarity in the number of compartments that compose the various honeycomb-like lattices. In conclusion, the present findings support a unified model of the AChE arrangement within the intermediate layers of the mammalian colliculus; the model comprehensively incorporates the classical description of the patchy and stripy features of the enzyme distribution. We hypothesize here that the modular AChE arrangement might be the anatomical basis for collicular vectorial encoding of orienting movements.