Qualitative analysis of generalized multistage epidemic model with immigration.

A model with multiple disease stages is discussed; its main feature is that it considers a general incidence rate, functions for death and immigration rates in all populations. We show via a suitable Lyapunov function that the unique endemic equilibrium is globally asymptotically stable. We conclude that, in order to obtain the existence and global stability of the equilibrium point of general models, conditions must be imposed on the functions present in the model.

Mathematical model of interaction and Coliphages.

We propose a mathematical model based in ordinary differential equations between bacterial pathogen and Bacteriophages to describe the infection dynamics of these populations, for which we use a nonlinear function with an inhibitory effect. We study the stability of the model using the Lyapunov theory and the second additive compound matrix and perform a global sensitivity analysis to elucidate the most influential parameters in the model, besides we make a parameter estimation using growth data of bacteria in presence of Coliphages (bacteriophages that infect ) with different multiplicity of infection. We found a threshold that indicates whether the bacteriophage concentration will coexist with the bacterium (the coexistence equilibrium) or become extinct (phages extinction equilibrium), the first equilibrium is locally asymptotically stable while the other is globally asymptotically stable depending on the magnitude of this threshold.

Global stability analysis for a model with carriers and non-linear incidence rate.

We analysed a epidemiological model with varying populations of susceptible, carriers, infectious and recovered (SCIR) and a general non-linear incidence rate of the form [Formula: see text]. We show that this model exhibits two positive equilibriums: the disease-free and disease equilibrium. We proved using the Lyapunov direct method that these two equilibriums are globally asymptotically stable under some sufficient conditions over the functions , , .

Bond strength of repaired amalgam restorations.

This in vitro study investigated the interfacial flexural strength (FS) of amalgam repairs and the optimal combination of repair materials and mechanical retention required for a consistent and durable repair bond. Amalgam bricks were created, each with 1 end roughened to expose a fresh surface before repair. Four groups followed separate repair protocols: group 1, bonding agent with amalgam; group 2, bonding agent with composite resin; group 3, mechanical retention (slot) with amalgam; and group 4, slot with bonding agent and amalgam.

Alternative treatments to replacement of defective amalgam restorations: results of a seven-year clinical study.

Background: The authors conducted a prospective cohort clinical study to investigate the effectiveness of alternative treatments to the replacement of defective amalgam restorations.

Methods: Fifty patients aged 21 through 77 years (mean age, 56 years) with 113 defective amalgam restorations that were diagnosed during treatment planning participated in the study. The authors assigned each tooth to one of five treatment groups: repair with amalgam (n = 20), sealing of defective margins (n = 23), refinishing (n = 23), replacement (n = 22) or no treatment (n = 25).

A long-term evaluation of alternative treatments to replacement of resin-based composite restorations: results of a seven-year study.

Objective: In a seven-year prospective cohort study, the authors assessed the longevity of defective resin-based composite (RBC) restorations that were not treated or were treated by means of repair, sealing, refinishing or total replacement. They also aimed to identify and quantify the main reasons clinicians diagnosed restorations as defective.

Methods: Thirty-seven patients--19 women and 18 men--who were aged 27 through 78 years (mean = 57 years, standard deviation [SD] = 13 years) and had a total of 88 defective restorations participated in the study.

Effect of size of defect on the repair strength of amalgam.

Objectives: This study tested the hypothesis that the size of repair sites on amalgam restorations with mechanical undercuts on the repair surface would affect interfacial strength using a 3-point bending test.

Method And Materials: Six groups of 12 rectangular bars each were fabricated from an admix alloy and a spherical alloy. Each specimen was cut into 2 equal-sized end sections, and 1 smaller midsection, which was discarded.

A clinical evaluation of a self-etching primer and a giomer restorative material: results at eight years.

Background: The authors evaluated the performance of a giomer restorative material (Beautifil, Shofu, Kyoto, Japan) with a self-etching primer (FL-Bond, Shofu) for posterior restorations.

Materials And Methods: Two clinicians placed 26 Class I restorations and 35 Class II restorations in 31 patients ranging in age from 21 to 62 years (mean age, 34 years). Inclusion criteria required patients to have molar-supported permanent dentition free of any edentulous spaces and no clinically significant occlusal interference, as well as one or more permanent molars or premolars requiring new or replacement Class I or II restorations.

The effect of mechanical undercuts on the strength of composite repair.

Background: The authors conducted an in vitro study to test the hypothesis that undercuts prepared in old composite restorations could improve the strength between the restoration and a flowable composite as repair material.

Methods: The authors used three composites to fabricate cylinders as repair substrates. The etched-only group was ground, etched, dried and built up with a flowable composite.

Use of zinc phosphate cement as a luting agent for Denzir trade mark copings: an in vitro study.

BACKGROUND: The clinical success rate with zinc phosphate cemented Procera crowns is high. The objective with this study was to determine whether CADCAM processed and zinc phosphate cemented Denzir copings would perform as well as zinc phosphate cemented Procera copings when tested in vitro in tension. METHODS: Twelve Procera copings and twenty-four Denzir copings were made.

Replacement of resin-based composite: evaluation of cavity design, cavity depth, and shade matching.

Objective: The aim of this study was to evaluate the effect of different cavity designs, cavity depths, and shade matching on the dimensions of Class I resin-based composite preparations during replacement of the restoration.

Method And Materials: Forty Class I cavity preparations were prepared in extracted premolars. The occlusal depths varied from 1.