Establishment of the epithelial attachment and connective tissue adaptation to implants installed under the concept of "platform switching": a histologic study in minipigs

Aim: To validate the platform switching concept at oral implants with respect to the preservation of the alveolar crestal bone levels in an animal model. Material & methods: Five minipigs received three implants each with a 0.25mm implant/ abutment mismatch and were placed flush (T(0)), 1 mm below (T(1)) and 1 mm above (T(+1)) the alveolar bony crest, and as a control, one conventionally restored implant placed at the bone level. The implants were randomly inserted flapless into the mandible. Four months after implant insertion, the animals were sacrificed, and undecalcified block sections were obtained and used for histological analyses. Results: The mean values for peri- implant bone resorption were 1.09 +/- 0.59mm (Control), 0.51 (+/- 0.27 mm, T(0)), 0.50 (+/- 0.46 mm, T(1)) and 1.30 (+/- 0.21 mm, T (+1)), respectively. Statistically significant differences (P< 0.05) were found among the test (T(0), T(-1)) and the control sites. Control implants presented an average biologic width length of 3.20mm (+/- 0.33), with a connective tissue adaptation compartment of 1.29mm (+/- 0.53) and an epithelial attachment of 1.91 mm (+/- 0.71). T(0), T(1) and T(+1) implants presented with a mean biologic width of 1.97mm (+/- 1.20), 2.70 mm (+/- 1.36) and 2.84mm (+/- 0.90), respectively, with a connective tissue adaptation compartment of 1.21mm (+/- 0.97), 1.21 mm (+/- 0.65) and 1.50 mm (+/- 0.70) and an epithelial attachment of 0.84 mm (+/- 0.93), 1.66 mm (+/- 0.88) and 1.35 mm (+/- 0.44), respectively. Differences between the configurations were mainly associated with the length of the epithelial attachment. The epithelial attachment was significantly longer in the C sites than in T(0) (P = 0.014). However, no other differences between configurations were detected. Conclusion: If the implants are positioned at the level of the alveolar bony crest, the platform switching concept may have a minor impact on the length of the epithelial attachment (0.84 vs. 1.91 mm), while the connective tissue adaptation compartment remains relatively unaffected. Moreover, platform switching resulted in less resorption of the alveolar crest (0.58 mm).

Concept of Matching Parallelepiped and its use in the correspondence problem

In this paper, the concept of Matching Parallelepiped (MP) is presented. It is shown that the volume of the MP can be used as an additional measure of `distance' between a pair of candidate points in a matching algorithm by Relaxation Labeling (RL). The volume of the MP is related with the Epipolar Geometry and the use of this measure works as an epipolar constraint in a RL process, decreasing the efforts in the matching algorithm since it is not necessary to explicitly determine the equations of the epipolar lines and to compute the distance of a candidate point to each epipolar line. As at the beginning of the process the Relative Orientation (RO) parameters are unknown, a initial matching based on gradient, intensities and correlation is obtained. Based on this set of labeled points the RO is determined and the epipolar constraint included in the algorithm. The obtained results shown that the proposed approach is suitable to determine feature-point matching with simultaneous estimation of camera orientation parameters even for the cases where the pair of optical axes are not parallel.

Two new species of Zetzellia Oudemans (Acari: Stigmaeidae) that threaten the concept of genera: Disgeneric marriage?

Two new species of Zetzellia Oudemans, Z. agistzellia sp. n. and Z. quasagistemas sp. n., are described from rubber trees of northwestern São Paulo State, Brazil. Females have clear features of Zetzellia, whereas males resemble Agistemus in some characters. Immatures are also described. The discovery of these species raises some problems concerning generic concepts in Stigmaeidae. Since features of different genera are present in the same species, the authors suggest that the scope of those genera should be reviewed. Copyright © 2005 Magnolia Press.

Dual path: A concept to improve the esthetic replacement of missing anterior teeth with a removable partial denture

The dual path of insertion concept for removable partial denture (RPD) design may be used in esthetically demanding situations. When compared to conventional RPDs, the main advantage of this design is the minimal use of clasps. This clinical report describes the treatment of a patient with an anterior maxillary edentulous area using a dual path RPD. The diagnostic cast was surveyed to ensure the adequacy of the undercuts on the mesial surfaces of the anterior abutments, where rigid minor connectors were placed. Inverted V-shaped canine cingulum rest seats were prepared to provide resistance to tooth movement during function. The dual path RPD concept allows excellent esthetic results, minimizes tooth preparation, and reduces the tendency toward plaque accumulation in a Kennedy class IV partially edentulous arch. © 2008 by The American College of Prosthodontists.

Conceptos y métodos de cálculo de la relación de precios del intercambio exterior = The concept of terms of trade and methods of computation

Incluye Bibliografía

A different concept of the private sector, a different concept of the public sector: notes for a Latin American debate

Presenta un analisis historico comparativo del proceso de modernizacion en America Latina y Europa y reflexiona sobre el debate entre lo publico y lo privado en los procesos de desarrollo economico de America Latina.

The concept of integration

Includes bibliography

The international division of industrial labour and the core-periphery concept

Includes bibliography

Foucault's heraclitism and the concept of history

Deleuze states that Foucault would have created a new relationship between men and history, a relationship other than that established by the philosophers of history. In order to specify the steps Foucault took to accomplish this invention, I shall support, according to Deleuze, Foucault s Heraclitism as the basis for a genuine Foucaultian concept of history. After outlining the risks taken by Foucault s concept of history, I observe this concept at work through the three periods that perform his thought: Archeology, Genealogy and Aesthetics of Existence. The main characters that embody his concept of history through these periods are: a) the discontinuous profile of history; b) the denaturalization of would-be unhistorical objects; c) the historical dimension of body; d) the eddies of subjectivation in history. We shall focus our inspection on the turn made along Foucault s work when he takes into a new account the theme of subjectivity, mostly in the last two volumes of the History of Sexuality. Thus, our attention turns to the subjectivity defined as a process, in order to investigate individual identity as the result of history.

The concept of quasi-integrability for modified non-linear Schrodinger models

We consider modifications of the nonlinear Schrodinger model (NLS) to look at the recently introduced concept of quasi-integrability. We show that such models possess an in finite number of quasi-conserved charges which present intriguing properties in relation to very specific space-time parity transformations. For the case of two-soliton solutions where the fields are eigenstates of this parity, those charges are asymptotically conserved in the scattering process of the solitons. Even though the charges vary in time their values in the far past and the far future are the same. Such results are obtained through analytical and numerical methods, and employ adaptations of algebraic techniques used in integrable field theories. Our findings may have important consequences on the applications of these models in several areas of non-linear science. We make a detailed numerical study of the modified NLS potential of the form V similar to (vertical bar psi vertical bar(2))(2+epsilon), with epsilon being a perturbation parameter. We perform numerical simulations of the scattering of solitons for this model and find a good agreement with the results predicted by the analytical considerations. Our paper shows that the quasi-integrability concepts recently proposed in the context of modifications of the sine-Gordon model remain valid for perturbations of the NLS model.

Exploring the coordination chemistry of isomerizable terpyridine derivatives for successful analyses of cis and trans isomers by travelling wave ion mobility mass spectrometry

The photochemical cis-trans isomerization of the 4-{4-[2-(pyridin-4-yl)ethenyl]phenyl}-2,2': 6',2''-terpyridine ligand (vpytpy) was investigated by UV-vis, NMR and TWIM-MS. Ion mobility mass spectrometry was performed pursuing the quantification of the isomeric composition during photolysis, however an in-source trans-to-cis isomerization process was observed. In order to overcome this inherent phenomenon, the isomerization of the vpytpy species was suppressed by complexation, reacting with iron(II) ions, and forming the [Fe(vpytpy)(2)](2+) complex. The strategy of "freezing" the cis-trans isomerizable ligand at a given geometric conformation was effective, preventing further isomerization, thus allowing the distinction of each one of the isomers in the photolysed mixture. In addition, the experimental drift times were related to the calculated surface areas of the three possible cis-cis, cis-trans and trans-trans iron(II) complex isomers. The stabilization of the ligand in a given conformation also allows us to obtain the cis-cis and cis-trans complexes exhibiting the ligand in the metastable cis-conformation, as well as in the thermodynamically stable trans-conformation.

The complexity of narrative interferes in the use of conjunctions in children with specific language impairment

PURPOSE: To verify the use of conjunctions in narratives, and to investigate the influence of stimuli's complexity over the type of conjunctions used by children with specific language impairment (SLI) and children with typical language development. METHODS: Participants were 40 children (20 with typical language development and 20 with SLI) with ages between 7 and 10 years, paired by age range. Fifteen stories with increasing of complexity were used to obtain the narratives; stories were classified into mechanical, behavioral and intentional, and each of them was represented by four scenes. Narratives were analyzed according to occurrence and classification of conjunctions. RESULTS: Both groups used more coordinative than subordinate conjunctions, with significant decrease in the use of conjunctions in the discourse of SLI children. The use of conjunctions varied according to the type of narrative: for coordinative conjunctions, both groups differed only between intentional and behavioral narratives, with higher occurrence in behavioral ones; for subordinate conjunctions, typically developing children's performance did not show differences between narratives, while SLI children presented fewer occurrences in intentional narratives, which was different from other narratives. CONCLUSION: Both groups used more coordinative than subordinate conjunctions; however, typically developing children presented more conjunctions than SLI children. The production of children with SLI was influenced by stimulus, since more complex narratives has less use of subordinate conjunctions.