Effect of RMGI Roughness and Dentin Bonding Primer on Shear Bond Strength of Sandwich-type Restorations.

BACKGROUND: The open sandwich technique is a reliable alternative to amalgam placement in deep proximal box preparations, where proper isolation and enamel bonding may not be possible. It is often difficult to prepare the box for composite placement without affecting the resin-modified glass ionomer (RMGI) that has been placed in the gingival portion. We hypothesized that RMGI surfaces that are roughened or those that use all steps in the manufacturing bonding protocol, including the priming solution, applied before placing a bonded composite increment, would have greater composite/RMGI shear bond strength. DESIGN AND METHODS: Shear bond strengths (SBS) of RMGI tested in the presence and absence of SiC roughening and primer-coating were tested using a fourth-generation dentin bonding agent to composite after thermocycling. Twenty specimens for four test conditions were fabricated and investigated. Data were subjected to a two-way ANOVA and the Holm-Sidak post-hoc test. RESULTS: Placing dentin primer on unabraded RMGI provided a statistically significant improvement in SBS, but only modestly. Furthermore, because bond failure consistently occurred within the RMGI itself, none of the surface modifications have a clinically relevant impact on SBS at the RMGI to the composite interface. CONCLUSIONS: Clinicians should be aware that they need not avoid RMGI abrasion and do not need to incorporate all components of a fourth-generation bonding system when covering an RMGI sandwich layer with composite.

A compendium of developmental gene expression in Lake Malawi cichlid fishes.

BACKGROUND: Lake Malawi cichlids represent one of a growing number of vertebrate models used to uncover the genetic and developmental basis of trait diversity. Rapid evolutionary radiation has resulted in species that share similar genomes but differ markedly in phenotypes including brains and behavior, nuptial coloration and the craniofacial skeleton. Research has begun to identify the genes, as well as the molecular and developmental pathways that underlie trait divergence. RESULTS: We assemble a compendium of gene expression for Lake Malawi cichlids, across pharyngula (the phylotypic stage) and larval stages of development, encompassing hundreds of gene transcripts. We chart patterns of expression in Bone morphogenetic protein (BMP), Fibroblast growth factor (FGF), Hedgehog (Hh), Notch and Wingless (Wnt) signaling pathways, as well as genes involved in neurogenesis, calcium and endocrine signaling, stem cell biology, and numerous homeobox (Hox) factors-in three planes using whole-mount in situ hybridization. Because of low sequence divergence across the Malawi cichlid assemblage, the probes we employ are broadly applicable in hundreds of species. We tabulate gene expression across general tissue domains, and highlight examples of unexpected expression patterns. CONCLUSIONS: On the heels of recently published genomes, this compendium of developmental gene expression in Lake Malawi cichlids provides a valuable resource for those interested in the relationship between evolution and development.