Indiana University-Purdue University Indianapolis (IUPUI) / Etching of enamel caries lesions has been demonstrated to enhance remineralization. However, this effect reaches a plateau after a period of time. This study aimed at investigating the effectiveness of additional acid etching on remineralization. Forty 1 mm × 2 mm human enamel blocks with chemically induced artificial incipient lesions were used. Ten specimens were randomly selected at the end of demineralization for transverse microradiography (TMR) analysis. The remaining specimens were then divided into three groups (n = 10). Group A was remineralized by a pH cycling system with 1100 ppm sodium fluoride for 20 days. In group B, the specimens were etched with 35-percent phosphoric acid for 30 s and then remineralized. Group C was remineralized by same procedure as group B plus and given an additional acid etch after 10 days of remineralization. Mineral density was measured by x-ray microtomography (µ-CT). The volumetric mineral content [VM (µm3×105)] was determined between 91 and 0-wt%. The µ-CT % mineral recovery (%) was calculated using the formula 100×(remineralize VM - demineralization VM) / (sound VM - demineralization VM). One-hundred-μm sections of demineralized and remineralized specimens were used to assess the mineral loss (IML: vol%×µm) and lesion depth (µm) using TMR. The three groups showed no significant difference in mineral change or mineral content for µ-CT or TMR lesion depth. The TMR IML showed a significant difference between the demineralized specimens and the three remineralized groups. The correlation between TMR IML and TMR lesion depth was 0.66 (p < 0.0001). The µ-CT percent mineral recovery from demineralization was correlated with neither TMR IML nor TMR lesion depth. When evaluated with µ-CT, the twice-acid-etched group presented lower mineral gain values than the group etched only once with acid. Also, the twice-etched group presented lower mineral gain and greater TMR IML compared with the non-acid etch group. TMR images revealed reduction of surface layer in the acid-etched groups, especially in the twice-etched group, in which significant reduction or loss of surface layer occurred. Based on these results, we conclude that additional acid etching with 35-percent phosphoric acid does not enhance remineralization compared with a single application of acid etching. We believe that the viable existence of the surface layer is essential for remineralization of the lesion. Further investigations into the accuracy of µ-CT to detect minute mineral changes in incipient caries lesions are probably needed.

Indiana University-Purdue University Indianapolis (IUPUI) / The majority of currently marketed fluoride varnishes (FV) have not been evaluated for their effectiveness in preventing dental caries. Fundamental research on FVs and how different formulations affect adherence to teeth, fluoride release into saliva and uptake by teeth is virtually non-existent. The objective of this work was to investigate the anti-caries potential, measured as fluoride release into saliva, change in surface microhardness of early enamel caries lesions, and enamel fluoride uptake, of multiple commercially available FVs. We have found that FVs differed in their release characteristics, rehardening capability, and ability to deliver fluoride to demineralized lesions. In addition to our in vitro work, we have conducted a clinical study that aimed to compare saliva and plaque fluid fluoride concentrations following the application of three commercially available FV treatments at predetermined post application time points. We also investigated the change in fluoride concentration in saliva and plaque fluid fluoride from baseline to each post application predetermined time point. We found that FVs varied in their release of fluoride into saliva and plaque fluid but shared common trends in release characteristics. The outcomes of our in vitro and in vivo investigations demonstrate a great variation in anti-caries potential of FVs. This may be attributed to different compositions and physical properties of the tested FVs.

This thesis studies how scientists and science were put to use in the passing of the 1962 Water Fluoridation Act. The law was created for a specific purpose: that of facilitating the continuation of the water fluoridation trials that had been under way in Norrköping until January 1962, when they were forced to cease, having been deemed illegal by the Supreme Administrative Court.  By studying the network of scientists who were either directly involved in or explicitly supportive of the Norrköping trials, and their actions as members of the two expert committees formed in the 1950’s by the Royal Board of Medicine, and which would come to greatly influence the legislative process, the thesis examines how personal and research interests transferred from Norrköping into the issue of nationwide fluoridation.  Using analytical tools gathered from Roger Pielke Jr. and Daniel Sarewitz, the thesis utilizes the concept of uncertainty to describe how scientists, in the political process, assumed different roles in order to further the cause of fluoridation on the one hand, but also to maintain an ideal image of the relationship between science and politics. Furthermore, the tension within the concept of scientization is examined, illuminating how the political end result - the law - is made possible by means of a balancing act between science’s claims to objective truth and the value-driven, often ethically charged discourse of politics.   Fianlly, the case of fluoridation is placed in the context of the welfare state and the public health project, where it emerges as a part of a broader political and societal renegotiation of the relationship between the individual and the state, which I argue was taking place in Sweden during ”the long fifties”. / Uppsatsen studerar hur forskare och vetenskap kom till användning i skapandet av 1962 års Lag om tillsättande av fluor till vattenledningsvatten. Lagen kom till med ett specifikt syfte, nämligen att möjliggöra för en fortsättning av de försök med fluoridering av dricksvatten som hade pågått i Norrköping fram till januari 1962, då de tvingats att upphöra efter att ha bedömts som olagliga av Regeringsrätten.  Genom att studera det nätverk av forskare som knöts till Norrköpingsförsöken, antingen som direkt involverade eller som förespråkare, och hur dessa agerade som medlemmar av de två expertkommittéer som tillsattes av Medicinalstyrelsen för att utreda frågan om fluoranvändning i kariesförebyggande syfte, vilka kom att utöva ett betydande inflytande på lagstiftningsprocessen, undersöker uppsatsen hur forsknings- och personliga intressen överfördes från Norrköping till frågan om rikstäckande vattenfluoridering.  Med hjälp av analytiska verktyg hämtade från Roger Pielke Jr. och Daniel Sarewitz, tar uppsatsen fasta på begreppet osäkerhet för att beskriva hur forskarna i den politiska processen antog olika roller, i syfte att dels främja fluorideringen som sådan, men också att upprätthålla rådande ideal om relationen mellan vetenskap och politik. Vidare undersöks spänningen i den process som Roger Pielke kallar scientization, och hur det politiska slutresultatet - lagen - blev verklighet till följd av en balansgång mellan vetenskapens anspråk på objektiv sanning och politikens värderingsdrivna och ofta etiskt färgade diskurs.  Slutligen placeras fallet med vattenfluorideringen i välfärdsstatens och folkhälsoprojektets kontext, där det framträder som en del av en bredare politisk och samhällelig omförhandling av relationen mellan individ och samhälle, som jag menar ägde rum i Sverige under ”det långa femtiotalet”.