Introdução - A política de fluoretação das águas de abastecimento público requer aplicação contínua desta medida em níveis adequados de flúor. O controle operacional é realizado pelas empresas de saneamento ao adicionar flúor às águas, cuja medida deve ser complementada pela ação dos sistemas de vigilância segundo o princípio do heterocontrole. Sistemas de vigilância lidam com informações de interesse público, nos marcos legais desenvolvidos pelos Estados. No mundo contemporâneo, tais marcos implicam contemplar o direito de acesso à informação. Objetivo - Descrever o sistema de vigilância da fluoretação da água no município de São Paulo, no período 1990-2011. Método - Pesquisa baseada em dados secundários disponibilizados pela Secretaria Municipal de Saúde de São Paulo, no período 1990-2011. Os teores de fluoreto nas amostras foram classificados segundo as dimensões de risco e benefício para fluorose e cárie dentária, avaliados concomitantemente. Adicionalmente, realizou-se revisão bibliográfica do marco legal brasileiro que trata da Lei de Acesso à Informação (LAI), tendo em vista que dados produzidos pelos sistemas de vigilância em saúde são de interesse público. Resultados - Foram analisadas 19.071 amostras. A média anual de registros identificados no período de pontos fixos atingiu 647 amostras, correspondendo a um valor acima do necessário para a cobertura total do sistema (n=180). A média anual de registros foi ainda maior para o período de pontos variáveis, com 1.340 amostras. A média geral dos teores de flúor foi de 0,66 mg/l. Com relação à prevenção da cárie, 44 por cento das amostras representam benefício moderado e 54 por cento benefício máximo. Quanto à fluorose dentária, 99 por cento das amostras representam risco mínimo. Com relação à LAI, o período histórico contemporâneo se apresenta, no Brasil, como um cenário de possibilidades e desafios aos avanços dos modelos de vigilância em saúde, incluindo a qualidade da água, com potencial para ampliar as possibilidades de controle sobre as políticas públicas. Conclusão: O benefício preventivo quanto à cárie não foi aproveitado em seu potencial pleno. O risco para fluorose dentária foi baixo. O número de amostras anuais coletadas apresentou tendência de aumento no período estudado, registrando-se variações que se situaram, contudo, sempre acima do limite inferior capaz de assegurar a cobertura total do sistema. Tendo em vista as disposições da LAI, dados e informações produzidos pelos sistemas de vigilância da qualidade da água são de interesse público e, portanto, devem estar disponíveis integralmente / Introduction - The policy of community water fluoridation requires continuous application of this measure by the adequate use of fluoride levels. Operational control is carried out by drinking-water suppliers to add fluoride to the water, which measure must be complemented by action of surveillance systems on the principle of external control. Surveillance systems deal with information of public interest, within the legal frameworks developed by the States. In the contemporary world, such landmarks contemplate the right of access to information. Objective - To describe the surveillance system of drinking-water fluoridation in the city of Sao Paulo, in the period 1990-2011. Method - Research based on secondary data provided by the Municipal Health Secretary of Sao Paulo, in the period 1990-2011. Fluoride levels in the samples were classified according to the dimensions of risk and benefit related to fluorosis and dental caries, concurrently assessed. Additionally, it was carried out a literature review of the Brazilian legal framework that deals with the Law on Access to Information (LAI), considering that data produced by health surveillance systems are of public interest. Results - It was analyzed 19,071 samples. The average annual records identified between fixed points period reached 647 samples, corresponding to a value higher than necessary to cover the entire system (n = 180). The average of the variable annual record points was even greater for the period, with 1,340 samples. The overall average fluoride concentration was 0.66 mg/l. With respect to the prevention of caries, 44 per cent of the samples represent moderate benefit and 54 per cent maximum benefit. As for dental fluorosis, 99 per cent of the samples represented minimal risk. With respect to LAI, the contemporary historical period presented in Brazil, as a scenario for possibilities and challenges to the improvement of health surveillance models, including water quality, with the potential to expand the possibilities of control over public policies. Conclusion: The preventive benefit concerning dental caries has not been tapped into its full potential. The risk for dental fluorosis was low. The annual number of collected samples showed a tendency to increase during the study period, registering variations which remained, however, always above the lower limit to ensure full coverage of the system. In view of the provisions of LAI, data and information produced by drinking-water surveillance systems are of public interest and therefore should be integrally available

Introdução - A política de fluoretação das águas de abastecimento público requer aplicação contínua desta medida em níveis adequados de flúor. O controle operacional é realizado pelas empresas de saneamento ao adicionar flúor às águas, cuja medida deve ser complementada pela ação dos sistemas de vigilância segundo o princípio do heterocontrole. Sistemas de vigilância lidam com informações de interesse público, nos marcos legais desenvolvidos pelos Estados. No mundo contemporâneo, tais marcos implicam contemplar o direito de acesso à informação. Objetivo - Descrever o sistema de vigilância da fluoretação da água no município de São Paulo, no período 1990-2011. Método - Pesquisa baseada em dados secundários disponibilizados pela Secretaria Municipal de Saúde de São Paulo, no período 1990-2011. Os teores de fluoreto nas amostras foram classificados segundo as dimensões de risco e benefício para fluorose e cárie dentária, avaliados concomitantemente. Adicionalmente, realizou-se revisão bibliográfica do marco legal brasileiro que trata da Lei de Acesso à Informação (LAI), tendo em vista que dados produzidos pelos sistemas de vigilância em saúde são de interesse público. Resultados - Foram analisadas 19.071 amostras. A média anual de registros identificados no período de pontos fixos atingiu 647 amostras, correspondendo a um valor acima do necessário para a cobertura total do sistema (n=180). A média anual de registros foi ainda maior para o período de pontos variáveis, com 1.340 amostras. A média geral dos teores de flúor foi de 0,66 mg/l. Com relação à prevenção da cárie, 44 por cento das amostras representam benefício moderado e 54 por cento benefício máximo. Quanto à fluorose dentária, 99 por cento das amostras representam risco mínimo. Com relação à LAI, o período histórico contemporâneo se apresenta, no Brasil, como um cenário de possibilidades e desafios aos avanços dos modelos de vigilância em saúde, incluindo a qualidade da água, com potencial para ampliar as possibilidades de controle sobre as políticas públicas. Conclusão: O benefício preventivo quanto à cárie não foi aproveitado em seu potencial pleno. O risco para fluorose dentária foi baixo. O número de amostras anuais coletadas apresentou tendência de aumento no período estudado, registrando-se variações que se situaram, contudo, sempre acima do limite inferior capaz de assegurar a cobertura total do sistema. Tendo em vista as disposições da LAI, dados e informações produzidos pelos sistemas de vigilância da qualidade da água são de interesse público e, portanto, devem estar disponíveis integralmente / Introduction - The policy of community water fluoridation requires continuous application of this measure by the adequate use of fluoride levels. Operational control is carried out by drinking-water suppliers to add fluoride to the water, which measure must be complemented by action of surveillance systems on the principle of external control. Surveillance systems deal with information of public interest, within the legal frameworks developed by the States. In the contemporary world, such landmarks contemplate the right of access to information. Objective - To describe the surveillance system of drinking-water fluoridation in the city of Sao Paulo, in the period 1990-2011. Method - Research based on secondary data provided by the Municipal Health Secretary of Sao Paulo, in the period 1990-2011. Fluoride levels in the samples were classified according to the dimensions of risk and benefit related to fluorosis and dental caries, concurrently assessed. Additionally, it was carried out a literature review of the Brazilian legal framework that deals with the Law on Access to Information (LAI), considering that data produced by health surveillance systems are of public interest. Results - It was analyzed 19,071 samples. The average annual records identified between fixed points period reached 647 samples, corresponding to a value higher than necessary to cover the entire system (n = 180). The average of the variable annual record points was even greater for the period, with 1,340 samples. The overall average fluoride concentration was 0.66 mg/l. With respect to the prevention of caries, 44 per cent of the samples represent moderate benefit and 54 per cent maximum benefit. As for dental fluorosis, 99 per cent of the samples represented minimal risk. With respect to LAI, the contemporary historical period presented in Brazil, as a scenario for possibilities and challenges to the improvement of health surveillance models, including water quality, with the potential to expand the possibilities of control over public policies. Conclusion: The preventive benefit concerning dental caries has not been tapped into its full potential. The risk for dental fluorosis was low. The annual number of collected samples showed a tendency to increase during the study period, registering variations which remained, however, always above the lower limit to ensure full coverage of the system. In view of the provisions of LAI, data and information produced by drinking-water surveillance systems are of public interest and therefore should be integrally available

No description available.

There have only been few investigations comparing total fluoride intake and the fluoride proportion excreted in urine in pre–school children. In addition, the results of available studies are conflicting. Total fluoride intake was assessed in 11 healthy children aged 3–6 years on 2 consecutive days and urinary fluoride excretion was determined. The duplicate–diet approach was used for the assessment of fluoride intake from solid and liquid foods. Fluoride intake from toothbrushing was calculated as the difference between the amount of fluoride in the paste put on the toothbrush and the drinking water (fluoride concentration 0.25 mg/l) used for rinsing vs. the fluoride amounts recovered in the toothpaste spat out and in the rinsing water. Use of fluoridated domestic salt and/or fluoride tablets was recorded. The children’s intake of fluoride from food averaged 202.5±116.2 μg F/day. They swallowed an average amount of 273.9±175.6 μg F/day when brushing their teeth. Daily fluoride ingestion from all sources totalled 930.7±391.5 μg or 53.0±21.4 μg/kg body weight. On average 51.5% of the fluoride ingested was excreted in urine. The wide interindividual variation makes it necessary to evaluate the urinary excretion rate for fluoride in larger study populations with varied fluoride exposure. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

The pre-analytical phase is known for being the most important step in the laboratory process to reach reliable test results. If handling, transport or preparation of the sample is performed incorrectly the results can deviate from the true value. Today, sampling tubes contains various additives to stabilize concentration levels. The aim of this study was to test a new sampling tube containing fluoride/citrate for glucose, lactate and homocysteine. It was also of interest to evaluate the stability of those three analytes in lithium-heparin, sodium-fluoride/potassium oxalate and fluoride/citrate tubes. To perform the sustainability study, a method verification was done for homocysteine in plasma. The study was performed in a hospital laboratory on the routine instrument Roche Cobas 6000 analyzer. Blood was drawn from 20 patients and was analyzed at the hospital laboratory in Gävle. The blood samples were transported frozen to the laboratory in Hudiksvall and were used in the method verification. For the sustainability study, blood was drawn from 10 healthy volunteers in lithium-heparin, sodium-fluoride/potassium oxalate and fluoride/citrate tubes. The method verification was approved. The results showed that glucose was stable for up to 72 hours in Vacuette Glycaemia tube with fluoride/citrate and this tube also gave more accurate results. Lactate and homocysteine were also stable in fluoride/citrate, but needs further studies. All three analytes were more stable if the sample tubes were centrifuged as soon as possible after blood collection. Fluoride/citrate tubes were stable without centrifugation directly.

There have only been few investigations comparing total fluoride intake and the fluoride proportion excreted in urine in pre–school children. In addition, the results of available studies are conflicting. Total fluoride intake was assessed in 11 healthy children aged 3–6 years on 2 consecutive days and urinary fluoride excretion was determined. The duplicate–diet approach was used for the assessment of fluoride intake from solid and liquid foods. Fluoride intake from toothbrushing was calculated as the difference between the amount of fluoride in the paste put on the toothbrush and the drinking water (fluoride concentration 0.25 mg/l) used for rinsing vs. the fluoride amounts recovered in the toothpaste spat out and in the rinsing water. Use of fluoridated domestic salt and/or fluoride tablets was recorded. The children’s intake of fluoride from food averaged 202.5±116.2 μg F/day. They swallowed an average amount of 273.9±175.6 μg F/day when brushing their teeth. Daily fluoride ingestion from all sources totalled 930.7±391.5 μg or 53.0±21.4 μg/kg body weight. On average 51.5% of the fluoride ingested was excreted in urine. The wide interindividual variation makes it necessary to evaluate the urinary excretion rate for fluoride in larger study populations with varied fluoride exposure. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Indiana University-Purdue University Indianapolis (IUPUI) / Purpose: The primary objective of this laboratory study was to investigate whether the ability of SDF to remineralize caries lesion is modulated by their baseline mineral distribution. The exploratory objective was to determine whether the staining caused by SDF is modulated by lesion mineral distribution. Materials and methods: This in vitro study utilized bovine permanent enamel specimens. SDF was compared to the clinical reference standard, 5% sodium fluoride varnish (FV), and deionized water (DIW) was the negative control. By utilizing three lesion creation protocols (methylcellulose [MeC], hydroxyethylcellulose [HEC], Carbopol [C907]), artificial caries lesions with different mineral distributions (n=20 per subgroup) were created in the enamel specimens Interventions were applied and the lesions remineralized using artificial saliva. Changes in mineral loss, lesion depth, mineral density of the surface zone, and lesion mineral distribution were determined using transverse microradiography. Throughout the study, color of the lesion and changes thereof were measured using a spectrophotometer. Data were analyzed by using two-way ANOVA. Pair-wise comparisons were performed using Fisher’s Protected Least Significant Differences to control the overall significance level at 5%. Results: For changes in mineral loss, DIW in MeC showed significantly greater change (more remineralization) than both SDF (p<0.01) and FV (p=0.01), which were not different from one another (p=0.13). There were no statistically significant differences between SDF and FV in the other lesions (C907 – p=0.18; HEC – p=0.56). For changes in lesion depth, there was no statistically significant interaction between study factors lesion protocol and treatments (p=0.23) as well as the individual factors lesion protocols (p=0.08) and treatments (p=0.82). For changes in surface zone mineral density, SDF showed significant change in mineral density compared to FV (p=0.02); however, SDF was not different from with DIW (p=0.25). For lesion mineral distribution, MeC exhibited the greater mineral loss in the lesion body and lowest mineral density at the surface zone. HEC lesions were the deepest but exhibited modest differences in mineral loss between the lesion body and the surface zone. C907 lesions were somewhat between MeC and HEC. SDF in MeC had the highest mineral gain in the surface zone, while DIW resulted in the highest mineral gain in the lesion body. SDF in HEC showed the highest mineral gain in the surface area compared to FV and DIW, with all treatments resulting in the largest mineral gain to a similar extent in the lesion body. In C907, SDF showed the most mineral gain in the lesion body compared to DIW and FV, while differences in the surface zone between treatments were less pronounced. For color changes post intervention, SDF showed more darkening in C907 and HEC lesions compared to MeC (p<0.01) and compared to FV and DIW. For post remineralization, SDF treated C907 lesions became significantly whiter (p<0.01) compared to SDF in MeC and HEC which continued to get darker. Conclusion: SDF did exhibit different remineralization abilities and behaviors and the modulation was based on lesion baseline mineral distribution. Staining resulting from SDF treatment varied significantly based on lesion mineral distribution.

Ziel: Diese Studie vergleicht die erosionsprotektiven Eigenschaften verschiedener Fluorid- und/oder Zinnlösungen bei unterschiedlichen pH-Werten. Es wird untersucht, ob fluorid- und/oder zinnhaltige Lösungen im sauren Milieu besser vor Erosionen schützen. Methoden: Hierfür wurden die Monosubstanzen Aminfluorid, Natriummono-fluorphosphat, Natriumfluorid, Zinnfluorid und Zinnchlorid bei einer Fluoridkonzentration von 500 ppm in vitro adjustiert auf die pH-Werte 4,5; 5,5 und 6,5 und in situ adjustiert auf den pH-Wert 4,5 untersucht. In einem In-vitro-Vorversuch wurden die Testlösungen zunächst bei den pH-Werten 4,5-6,5 gescreent. Der In-situ-Hauptversuch wurde mit dem wirksamsten pH-Wert 4,5 durchgeführt. Zur In-situ-Pellikelbildung wurden individuelle Schienen mit je 6 Prüfkörpern von 6 Proband*innen für 30 min oral inkubiert. Nach 1 min wurde für 60 s mit einer Lösung des pH-Wertes 4,5 gespült. Native und mit In-vitro- bzw. In-situ-Pellikel bedeckte Plättchen dienen als Kontrolle. Die Prüfkörper wurden für 120 s in HCl (pH 2,0; 2,3 und 3,0) inkubiert. Die Kalzium- und Phosphatfreisetzungen wurden photometrisch bestimmt (Arsenazo-III- und Malachitgrün-Methode). Ergebnisse: Alle Spüllösungen reduzieren die Mineralfreisetzung aus den Schmelzprüfkörpern verglichen mit der nativen Kontrolle. Im Vergleich zur In-vitro- und In-situ-Pellikel wird die Mineralfreisetzung durch die Monosubstanzen jedoch nicht vermindert. Die Kalzium- und Phosphatfreisetzungen aus den In-situ-Prüfkörpern sind geringfügig niedriger als aus den Proben der In-vitro-Versuchsreihe. Die Monosubstanzen des pH-Wertes 4,5 konnten die Kalzium- und Phosphatfreisetzung in vitro stärker reduzieren als die Lösungen der pH-Werte 5,5 oder 6,5. Der Erosionsschutz von Fluorid- und/oder Zinnlösungen wird im sauren Milieu verbessert. Zinnfluorid reduziert die Mineralfreisetzung in vitro und in situ am stärksten. Die erosionsprotektiven Eigenschaften von Zinnchlorid sind gleichwertig mit denen der konventionellen Lösungen Aminfluorid, Natriummonofluorphosphat und Natriumfluorid. Schlussfolgerungen: Fluorid- und Zinnionen interagieren im sauren Milieu stärker mit der Zahnoberfläche als bei neutraleren pH-Werten – der resultierende protektive Effekt ist somit ausgeprägter. Ein wichtiger Co-Faktor dabei sind die Zinnionen. Die In-situ-Pellikel bietet einen besseren Schutz vor Erosionen als die In-vitro-Pellikel. Daher sind In-situ-Versuche den In-vitro-Versuchen vorzuziehen. / Objective: The distinctive aspect of this study was to ascertain the erosion protective properties of various fluoride and/or stannous solutions at different pH values. The aim was to investigate whether fluoride- and/or tin-containing solutions provide better protection against erosion than solutions with higher pH values. Methods: In an in vitro experiment, amine fluoride, sodium monofluorophosphate, sodium fluoride, stannous fluoride, and stannous chloride at fluoride concentrations of 500 ppm were initially screened and pH values of 4.5; 5.5 and 6.5. The in situ main experiment was conducted at the most effective pH value of 4.5. Individual trays with 6 test specimens for six participants were orally incubated for 30 minutes. After 1 minute, a 60-second rinse was performed with a test solution at pH 4.5. Native and in vitro- or in situ-covered specimens were used as controls. The test specimens were then incubated in HCl (pH 2.0, 2.3, and 3.0) for 120 seconds, and calcium and phosphate release was determined photometrically using the Arsenazo III and Malachite Green methods. Results: All rinsing solutions reduced mineral loss from the enamel test specimens compared to the native control. However, the monosubstances did not significantly reduce mineral loss compared to the in vitro or in situ pellicles. The calcium and phosphate releases from the in situ specimens were slightly lower than those from the in vitro series. The fluoride substances at pH 4.5 exhibited a stronger reduction in calcium and phosphate release in vitro compared to solutions at pH values of 5.5 or 6.5. The erosion protective properties of fluoride and/or stannous solutions were enhanced in an acidic environment. Among all substances, stannous fluoride exhibited the greatest reduction in mineral release both in vitro and in situ. The erosion protection of stannous chloride was comparable to the protection offered by amine fluoride, sodium monofluorophosphate, and sodium fluoride solutions. Conclusions: Fluoride and tin ions interact more strongly with the tooth surface in an acidic environment compared to more neutral pH values, resulting in a more pronounced protective effect. Stannous ions play an important role in this process. In situ pellicles offer better protection against erosions than in vitro pellicles. Therefore, in situ experiments are preferable to in vitro experiments.

The growth of sensors and sensing technologies have made significant impact in our day-to-day life. The five principle sensory organs of our body should perform effectively, so that we can lead a good healthy life. Apart from these natural sensors, there are man-made sensors that helps us to cope with diseases, organ failure etc. and enable us to lead a normal life. In recent years, with the prevalence of new kind of diseases, the need for new type of biomedical sensors is becoming very important. As a result, sensors used for biomedical applications have become an emerging technology and rapidly growing field of research. The aim of the present thesis work is to use the piezoelectric property of Polyvinylidene Fluoride (PVDF) film for the development of biomedical sensor and studying its application for human respiration/breathing related abnormalities. PVDF nasal sensor was designed in cantilever configuration and detailed theoretical analysis of the same was performed. Based on theoretical and experimental results, the PVDF nasal sensor dimensions were optimized. Suitable signal conditioning circuitry was designed and a measurement system for biomedical application was developed. The developed PVDF nasal sensor was calibrated using MEMS low-pressure sensor. The PVDF nasal sensor system has been applied in different biomedical applications namely, (i) to monitor human respiration pattern, (ii) to identify different Respiration Rates (RR), (iii) to evaluate Deviated Nasal Septum (DNS) in comparison with other objective method and, (vi) to clinically investigate nasal obstruction in comparison with subjective method. The thesis is divided into seven chapters. Chapter 1 This chapter gives a general introduction about biomedical sensors, piezoelectric sensing principle and PVDF polymer films along with the relevant literature survey. The brief introduction as well as literature survey of techniques used to monitor human respiration and to measure nasal obstruction is also included in this chapter. Chapter 2 This chapter gives details about the design of the PVDF nasal sensor in the cantilever configuration for sensing nasal airflow along with the relevant theoretical equations. Also, the details on the optimization of the PVDF nasal sensor dimensions based on the theoretical and experimental analysis are presented. Chapter 3 This chapter reports the designing of the necessary signal conditioning hardware along with the data acquisition unit for the PVDF nasal sensor. The signal conditioning hardware unit made consists of charge amplifier, low-pass filter and an amplifier. Besides, a complete measurement system for biomedical application was developed using PVDF nasal sensor and its merits and demerits were discussed. Chapter 4 In this chapter, an experimental set-up for measuring human respiration/breathing pressure using water U-tube manometer has been described. Also, the calibration procedure followed for the developed PVDF nasal sensor using a Micro Electro Mechanical Systems(MEMS) low pressure sensor is reported. Apart from these, the details on the measurement of deflection of the PVDF cantilever sensing element using laser displacement setup are provided. In addition, the PVDF nasal sensor was also calibrated for various air flow rates. At the end, a study has been reported on optimizing the position the PVDF nasal sensor with respect to human nose. Chapter 5 This chapter is divided into two sections, Section 5.1: This section describes the applicability of the PVDF nasal sensor using its piezoelectric property to monitor the human respiration pattern of each nostril simultaneously. The results of the PVDF nasal sensor have also been evaluated by comparing with Respiratory Inductive Plethysmograph(RIP) technique in normal subjects. Section 5.2: In this section, PVDF nasal sensor, RIP and Nasal Prongs (NP) techniques were used to measure the RR of healthy adults. The aim here was to evaluate the presently developed PVDF nasal sensor for identifying different RR compared to „Gold standard‟ RIP and NP methods. Chapter 6 This chapter is divided into two sections. Section 6.1: This section reports about the utilization of the developed PVDF nasal sensor for clinical application on the patient population. For this purpose, the performance of the PVDF nasal sensor measurements has been compared with the Peak Nasal Inspiratory Flow(PNIF) objective technique and visual analog scale (VAS). Section 6.2: This section describes about the use of PVDF nasal sensor system to measure nasal obstruction caused due to DNS objectively. Further, the results of the PVDF nasal sensor were compared with subjective techniques namely, VAS and clinician scale in patients and control group. Chapter 7 This chapter is composed of two sections. Section 7.1: This section summarizes the salient features of the work presented in this thesis. Section 7.2: This section reports a scope for carrying out further work.

Cette thèse décrit comment la morphologie et le polymorphisme de membranes en fluorure de poly(vinylidène) (PVDF) préparées par séparation de phase induite par la vapeur d'eau (VIPS) et par un non-solvant liquide peuvent être ajustés par la température à laquelle le PVDF est dissous (Tdis) pour former la solution de coulée. Les résultats montrent que Tdis présente une transition, notée comme la température de dissolution critique (Tcri), à partir de laquelle la morphologie et le polymorphisme des membranes changent radicalement. Ce phénomène observé pour les trois solvants, N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), and N,M-dimethylformamide (DMF), et les non-solvants (eau et une série d'alcools) utilisés dans cette étude peut être considéré comme général. La cristallisation a lieu avant la démixtion L-L quelle que soit Tdis. Pour une Tdis supérieure à Tcri, les membranes se présentent sous forme de nodules (cristallite forme beta) dont la taille décroît lorsque Tdis diminue. Ce domaine a été dénommé "à grossissement libre" car les chaînes de polymère peuvent cristalliser librement pendant la séparation de phase. Pour une Tdis inférieure à Tcri, des membranes avec une structure bi-continue (cristallite forme alpha) sont obtenues. Ce domaine a été appelé "à grossissement empêché" dans la mesure où la séparation de phase s'accompagne d'une gélification. Nous avons démontré que la morphologie et le polymorphisme cristallin des membranes de PVDF peuvent ainsi être contrôlés par la Tdis et la vitesse d'échange avec le non-solvant. Ces résultats sont interprétés en termes d'auto germination et de compétition entre gélification, cristallisation et démixtion L-L. / This dissertation shows how the morphology and polymorphism of poly(vinylidene fluoride) (PVDF) membranes prepared by using vapor-induced phase separation (VIPS) and liquid-induced phase separation (LIPS) were tuned by varying the dissolution temperature at which PVDF was dissolved (Tdis) to form the casting solution. We observed a transition temperature denoted by critical dissolution temperature, Tcri, across which the morphology and polymorphism of membranes (obtained by VIPS) drastically changed. The phenomenon was considered as general, as a Tcri was observed for all the three solvents N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF) and the non-solvents, water and a series of alcohols, used in the present study. No matter which Tdis we used, polymer crystallization occurred prior to the L-L demixing. With Tdis above Tcri, the prepared membranes were composed of nodules (mainly in beta crystalline form) and the size of polymer domains decreased as the Tdis decreased. Because the polymer chains could freely coarsen to a large domain during the phase separation, we called the system free coarsening. With Tdis below Tcri, membranes with lacy (bi-continuous) structure (mainly in alpha crystalline form) were obtained. Because the polymer solution gelled during the phase separation, we called the system hindered coarsening. It was proven that PVDF membrane morphology and crystalline polymorphs can be monitored by Tdis and the solvent-nonsolvent exchange rate. These results were discussed in terms of self-seeding effect and competition between the gelation, crystallisation and L-L demixing.