Posterior composite restoration update: focus on factors influencing form and function.

Restoring posterior teeth with resin-based composite materials continues to gain popularity among clinicians, and the demand for such aesthetic restorations is increasing. Indeed, the most common aesthetic alternative to dental amalgam is resin composite. Moderate to large posterior composite restorations, however, have higher failure rates, more recurrent caries, and increased frequency of replacement.

Durable bonds at the adhesive/dentin interface: an impossible mission or simply a moving target?

Composite restorations have higher failure rates, more recurrent caries and increased frequency of replacement as compared to dental amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and failure. The gingival margin of composite restora tions is particularly vulnerable to decay and at this margin, the adhesive and its seal to dentin provides the primary barrier between the prepared tooth and the environment.

Variations on a theme: diversification of cuticular hydrocarbons in a clade of cactophilic Drosophila.

Background: We characterized variation and chemical composition of epicuticular hydrocarbons (CHCs) in the seven species of the Drosophila buzzatii cluster with gas chromatography/mass spectrometry. Despite the critical role of CHCs in providing resistance to desiccation and involvement in communication, such as courtship behavior, mating, and aggregation, few studies have investigated how CHC profiles evolve within and between species in a phylogenetic context. We analyzed quantitative differences in CHC profiles in populations of the D.

Low satellite DNA variability in natural populations of Drosophila antonietae involved in different evolutionary events.

Drosophila antonietae is a cactophilic species that is found in the mesophilic forest of the Paraná-Paraguay river basin and in the dunes of the South Atlantic coast of Brazil. Although the genetic structure of the Paraná-Paraguay river basin populations has already been established, the relationship between these populations and those on the Atlantic coast is controversial. In this study, we compared 33 repetitive units of pBuM-2 satellite DNA isolated from individuals from 8 populations of D.

Adhesive/Dentin interface: the weak link in the composite restoration.

Results from clinical studies suggest that more than half of the 166 million dental restorations that were placed in the United States in 2005 were replacements for failed restorations. This emphasis on replacement therapy is expected to grow as dentists use composite as opposed to dental amalgam to restore moderate to large posterior lesions. Composite restorations have higher failure rates, more recurrent caries, and increased frequency of replacement as compared to amalgam.

Phenotypic variation of the Aedeagus of Drosophila serido vilela & sene (Diptera: Drosophilidae).

Drosophila serido Vilela & Sene is a polytypic and cactophilic species with broad geographic distribution in Brazil. The morphology of the aedeagi of eight natural populations of D. serido was analyzed.

Sequence analysis, chromosomal distribution and long-range organization show that rapid turnover of new and old pBuM satellite DNA repeats leads to different patterns of variation in seven species of the Drosophila buzzatii cluster.

We aimed to study patterns of variation and factors influencing the evolutionary dynamics of a satellite DNA, pBuM, in all seven Drosophila species from the buzzatii cluster (repleta group). We analyzed 117 alpha pBuM-1 (monomer length 190 bp) and 119 composite alpha/beta (370 bp) pBuM-2 repeats and determined the chromosome location and long-range organization on DNA fibers of major sequence variants. Such combined methodologies in the study of satDNAs have been used in very few organisms.

Tooth structure and fracture strength of cavities.

This study evaluated, in vitro, the loss of tooth substance after cavity preparation for direct and indirect restorations and its relationship with fracture strength of the prepared teeth. Sixty sound human maxillary first premolars were assigned to 6 groups (n=10). MOD direct composite cavities (Groups I, II and III) and indirect inlay cavities (Groups IV, V and VI) were prepared maintaining standardized dimensions: 2-mm deep pulpal floors, 1.

Low rates of homogenization of the DBC-150 satellite DNA family restricted to a single pair of microchromosomes in species from the Drosophila buzzatii cluster.

A satellite DNA family, termed DBC-150, comprises slightly GC-rich repeat units of approximately 150 bp that were isolated (by DNA digestions or PCR) from the genome of all seven Drosophila species from the buzzatii cluster (repleta group). The presence of subrepeats suggests that part of the extant DBC-150 monomer originated by the duplication of small sequence motifs. The DBC-150 family is compared to the previously described pBuM satDNA family, an abundant component of the genome of five species of the cluster.

Conservation of pBuM-2 satellite DNA sequences among geographically isolated Drosophila gouveai populations from Brazil.

In this study, we have compared 34 repetition units of pBuM-2 satellite DNA of individuals from six isolated populations of Drosophila gouveai, a cactophilic member of Drosophila buzzatii cluster (repleta group). In contrast to the results of previous morphological and molecular data, which suggest differentiation among the D. gouveai populations, the sequences and the cluster analysis of pBuM-2 monomers showed that this repetitive element is highly conserved among the six D.

Aedeagus morphology as a discriminant marker in two closely related cactophilic species of Drosophila (Diptera; Drosophilidae) in South America.

Drosophila serido and D. antonietae are sibling species belonging to the Drosophila buzzatii cluster. Morphologically, they can only be discriminated by quantitative traits.

Cactophilic Drosophila in South America: a model for evolutionary studies.

The Drosophila buzzatii cluster is composed of seven cactophilic species and their known geographical distribution encompasses the open vegetation diagonal, which includes the morphoclimatic Domains of the Caatinga, Chaco and Cerrado, which are situated between the Amazon and the Atlantic forests. Besides these areas, these cactophilic species are also found in a narrow strip along the Atlantic coast from northeastern Brazil to the southern tip of the country. The hypothesis of vicariant events, defining the core areas of each species, is proposed to explain the historical diversification for the cluster.

Population genetic structure of two columnar cacti with a patchy distribution in eastern Brazil.

The genetic variability and population genetic structure of six populations of Praecereus euchlorus and Pilosocereus machrisii were investigated. The genetic variability in single populations of Pilosocereus vilaboensis, Pilosocereus aureispinus, and Facheiroa squamosa was also examined. All of these cacti species have a patchy geographic distribution in which they are restricted to small areas of xeric habitats in eastern Brazil.

Evolutionary turnover of two pBuM satellite DNA subfamilies in the Drosophila buzzatii species cluster (repleta group): from alpha to alpha/beta arrays.

The pBuM satellite DNA family was studied in seven Drosophila species from the buzzatii cluster (within the large Drosophila repleta group). The pBuM repeats are slightly AT-rich and show high levels of intraspecific sequence homogeneity. The pBuM family can be divided into two subfamilies.

Characterisation and interpopulation variability of a complex HpaI satellite DNA of Drosophila seriema (repleta group).

A HpaI satellite DNA has been isolated and characterised from the genome of Drosophila seriema, a cactus-breeding species endemic to the rock fields of the Espinhaço Range in Brazil. The monomer sequences are slightly A + T rich (66%) and there is a significant variation of repetition length (343-391 bp). The length variability is mainly due to a 22 bp indel in some repeats and the presence of a highly variable region characterised by several DNA rearrangements, including indels, inversions and duplications of small sequence segments.

On the pBuM189 satellite DNA variability among South American populations of Drosophila buzzatii.

The pBuM189 satellite DNA was analysed in Drosophila buzzatii populations that cover most of the species distribution in South America. This satDNA consists of A + T-rich monomers of 189 bp and previous studies showed a fast rate of evolutionary change of this component of D. buzzatii genome.

Nested cladistic analysis of Brazilian populations of Drosophila serido.

The effects of Quaternary climatic cycles were investigated in Drosophila serido, a Brazilian cactophilic fly widely distributed outside the Amazonian region. Previous studies have indicated this species displays remarkable karyotypic, male genitalia, and mtDNA variation, so much so that it has been described as a species complex, or superspecies. In the present study we expand the analysis of the mtDNA COI gene on D.