ABSTRACT
Frameworks made of carbon fibre-reinforced composites (CFRC) seem to be a viable alternative to traditional metal frameworks in implant prosthodontics. CFRC provide stiffness, rigidity and optimal biocompatibility. The aim of the present prospective study was to compare carbon fibre frameworks versus metal frameworks used to rigidly splint implants in full-arch immediate loading rehabilitations. Forty-two patients (test group) were rehabilitated with full-arch immediate loading rehabilitations of the upper jaw (total: 170 implants) following the Columbus Bridge Protocol with four to six implants with distal tilted implants. All patients were treated with resin screw-retained full-arch prostheses endowed with carbon fibre frameworks. The mean follow-up was 22 months (range: 18-24). Differences in the absolute change of bone resorption over time between the two implant sides (mesial and distal) were assessed performing a Mann-Whitney U-test. The outcomes were statistically compared with those of patients rehabilitated following the same protocol but using metal frameworks (control group: 34 patients with 163 implants - data reported in Tealdo, Menini, Bevilacqua, Pera, Pesce, Signori, Pera, Int J Prosthodont, 27, 2014, 207). Ten implants failed in the control group (6·1%); none failed in the test group (P = 0·002). A statistically significant difference in the absolute change of bone resorption around the implants was found between the two groups (P = 0·004), with greater mean peri-implant bone resorption in the control group (1 mm) compared to the test group (0·8 mm). Carbon fibre frameworks may be considered as a viable alternative to the metal ones and showed less marginal bone loss around implants and a greater implant survival rate during the observation period.
Subject(s)
Carbon , Dental Alloys , Dental Implantation, Endosseous/instrumentation , Dental Implants , Dental Prosthesis, Implant-Supported , Denture Retention/instrumentation , Immediate Dental Implant Loading/methods , Alveolar Bone Loss , Carbon Fiber , Dental Implantation, Endosseous/methods , Dental Prosthesis, Implant-Supported/instrumentation , Denture Design , Female , Follow-Up Studies , Humans , Male , Maxilla/surgery , Middle Aged , Prospective Studies , Treatment OutcomeABSTRACT
A mathematical model for the delivery of drug directly to the macrophages by using the phagocytosis of senescent red blood cells is proposed. The model is based on the following assumption: At time t = 0 a preassigned red blood cell population n(0,a) = phi (a), a > 0, loaded by the drug, is injected in the blood circulation. Among the cells of that population only those with an age a > or = a (a = 120 days) will be phagocytosed by macrophages. Of course, the lifetime of the drug must be higher than a. Within the red blood cells it cannot be metabolized, neither can it diffuse through their membranes. The emphasis of the paper is on the mathematical properties and on the formulation of the control problem.
Subject(s)
Drug Therapy/methods , Erythrocytes/physiology , Macrophages , Models, Theoretical , Phagocytosis , Pharmaceutical Preparations/administration & dosage , Erythrocyte Aging , Humans , PharmacokineticsABSTRACT
The problem of optimal dosage is studied for the administration of ddCyd using erythrocytes as carriers and bioreactors. The volume of erythrocytes and the initial amount of drug to be loaded have to be determined in such a way that the duration of the therapeutic effect is maximized without exceeding the toxic threshold. It is found that the optimal control is unique and it is at the upper vertex of the set of the admissible controls. A more general case is also briefly discussed.
Subject(s)
Erythrocytes , Models, Biological , Zalcitabine/administration & dosage , Drug Carriers , Humans , MathematicsABSTRACT
The growth of a species feeding on a limiting nutrient supplied at a constant rate is modelled by chemostat-type equations with a general nutrient uptake function and delayed nutrient recycling. Conditions for boundedness of the solutions and the existence of non-negative equilibria are given for the integrodifferential equations with distributed time lags. When the time lags are neglected conditions for the global stability of the positive equilibrium and for the extinction of the species are provided. The positive equilibrium continues to be locally stable when the time lag in recycling is considered and this is proved for a wide class of memory functions. Computer simulations suggest that even in this case the region of stability is very large, but the solutions tend to the equilibrium through oscillations.
Subject(s)
Eukaryota/growth & development , Models, Biological , Models, Statistical , Kinetics , Mathematics , Population GrowthABSTRACT
A non-linear three-compartment model is proposed to describe a new strategy for the administration of 2',3'-dideoxycytidine (ddCyd) in the treatment of HIV infections. The drug is injected after having been encapsulated in a non-diffusible form (ddCMP) into erythrocytes. Numerical solutions show that by this treatment the highest ddCyd blood concentration is strongly reduced and in turn its toxicity, while long-lasting therapeutic effect is assured. The model is compared with experimental data in vitro.
