Low concentrations (1-10mg/mL) of double antibiotic paste (DAP) have demonstrated antibacterial properties in regenerative endodontics. The aim of this study was to evaluate if DAP made radiopaque (RoDAP) with barium sulfate has antibacterial effects against bacterial isolates from a mature and immature tooth with necrotic pulp. Clinical bacterial isolates were obtained from the canals of mature and immature teeth with necrotic pulps during root canal therapy or a regenerative procedure, respectively. Bacterial isolates were grown anaerobically for three weeks on 4x4mm dentin specimens prepared from extracted human teeth (n=48 per biofilm type). The dentin specimens were allocated into six groups and treated as follows: 1mg/mL RoDAP, 10mg/mL RoDAP, calcium hydroxide (UltraCal), placebo (barium sulfate in methylcellulose), no treatment, and no bacteria or treatment (sterile control). After one week of treatment the biofilm was detached and biofilm disruption assays were conducted to determine the bacterial numbers (CFUs/mL). The data was analyzed using Wilcoxon Rank Sum tests followed by pairwise comparisons. 1 and 10 mg/mL RoDAP as well as calcium hydroxide demonstrated significant antibacterial effects against the tested bacterial isolates. The placebo paste did not demonstrate any significant antibacterial effects. No significant difference in antibacterial effects was found against isolates from both mature and immature teeth regardless of the type of treatment. Both 1 and 10 mg/mL RoDAP demonstrated significant antibacterial effects against bacterial isolates from mature and immature teeth with necrotic pulps. RoDAP can be beneficial clinically since its adequate placement within the canal system can be confirmed radiographically.

Vertebroplasty is a new technique in orthopedic surgery for stabilizing fractured vertebra. In this technique acrylic bone cement as a biocompatible material is injected through a cannula inside of vertebra. There are several concerns in this technique that the most serious one is cement leakage out of vertebra. The main reasons are improper viscosity and lack of visibility. Clinicians who practice vertebroplasty use commercial highly concentrated radiopaque acrylic bone cement (more than 25%BaSO[subscript 4] or ZrO[subscript 2]) or a cement with manually added radiopaque agents. High density materials with attenuation under X-ray are good alternatives compared to conventional radiopaque agents (BaSO[subscript 4] or ZrO[subscript 2]) in acrylic bone cement for application in vertebroplasty. In the first part of this study, thermal and rheological properties of modified acrylic bone cement with conventional radiopaque agent (Barium Sulfate, BaSO[subscript 4]) are studied. Additions of barium sulfate are in the form of substitute or excess. In substitute formulation, barium sulfate is replaced with the same weight of powder and liquid to powder ratio kept constant. In the excess formulation, barium sulfate added as excess and liquid to powder ratio decreased. In the second part of this study, high density radiopaque agents are used as alternative radiopacifier. Experimental design technique is used to study the effect of X-ray conditions, concentration, type, and size of radiopaque agents on the visibility of bone cement. The visibility of bone cement was quantified by the measurement of contrast index. In the first project, it was found that the setting time increased with the increase of concentration of radiopacifier in substitute formulation of barium sulfate bone cement. With increase of barium sulfate concentration, excess formulations showed higher residual monomer but for substitute cement, we had a decreasing trend. Acrylic bone cements with excess formulation had higher initial viscosity compared to reference or substitute but the variation of viscosity with time was lower for substitute formulation and cements had higher working time. In the second project, contrast index was the same for barium sulfate, tungsten, and zirconium in the lower voltage but in higher voltage of X-ray lamp, tungsten and zirconium gave higher contrast index. Variation of current in X-ray lamp changed the contrast index of cement slightly compared to the effect of voltage. Bone cement with nano tungsten had higher contrast index compared to the cement with micro size tungsten although micro size zirconium as radiopacifier gave higher contrast index than nano size zirconium.

A white spot lesion (WSL) is defined as enamel porosity, which could be due to an enamel defect or an initial carious lesion. ICON® resin is a resin infiltrant that penetrates into the enamel porosity and seals the lesion, thus inhibiting the progression of caries. This method is micro-invasive; however, the resin is radiolucent and the clinician cannot detect the material using radiographs. In order to develop a radiopaque resin, understanding the pore size and pore structure in WSLs is helpful. Therefore, the aim of this study was to characterise: (1) the pore size and structure, (2) the incorporation of radiopaque agents into ICON® resin. Brunauer-Emmett-Teller (BET) and focused ion beam-scanning electron microscopy (FIB-SEM) were used to characterise the porosity in WSLs. The data showed the enamel prisms become more pronounced in the advanced areas of the WSLs and demineralisation occurs within or/and between the enamel prisms. The pore size could be as small as an enamel crystallite, 28x48nm. Nano-strontium hydroxyapatite (non-coated and coated) and strontium bioglass were made as radiopaque fillers and characterised using different techniques including fourier transform infrared spectroscopy (FTIR), BET, transmission electron microscopy (TEM), X-ray diffraction (XRD) and particle size measurements. The radiopaque fillers had micron-sized particles, which made them unsuitable for infiltration into WSLs despite their possible ability to remineralise the WSLs. Radiopaque monomers including bromine-methacrylate and tin-methacrylate were able to make ICON® resin radiopaque and they showed a similar viscosity, wettability and biocompatibility compared to ICON® resin. The X-ray microtomography (XMT) showed that the experimental radiopaque resins were able to infiltrate into the WSLs, artificial and natural lesions, and they could be detected using image subtraction. Backscattered electron (BSE) imaging after each step of application of materials showed that the etching pattern and etchant gel could be barriers for a successful infiltration of the resins into WSLs.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: Regenerative endodontic procedures require adequate disinfection of immature teeth with necrotic pulps. Regeneration endodontic procedures have been shown to increase width and length of dentin after disinfection of the root canal system with various antibiotic pastes such as double antibiotic paste (DAP). DAP is composed of an equal ratio of metronidazole and ciprofloxacin. After the root canal system is disinfected with DAP, it is later flushed out with 17-percent EDTA. There is a need for a radiopaque component in the DAP to facilitate proper placement. Following disinfection with DAP, a residual antibacterial effect is formed in dentin. It is not known if this effect is modified by making DAP radiopaque. Objectives: The residual antibacterial effects of a radiopaque double antibiotic paste against a bacterial isolate obtained from an immature tooth with necrotic pulp on radicular dentin will be explored utilizing various strengths of DAP (1 mg/mL, 10 mg/mL, and 25 mg/mL) after 1 week and 4 weeks. Materials and Methods: Dentin samples of 4x4-mm will be prepared from previously extracted human posterior teeth. The samples will be assigned to seven treatment groups in a random fashion (G1 will be treated with 25-, G2-10, and G3-1 mg/mL of radiopaque DAP. G4 will be treated with the radiopaque filler without DAP. G5 will be treated with Ca(OH)2 and G6 sterile water with bacterial biofilm, and G7 will be sterile water). The groups will be treated for both 1 week 4 weeks. These samples will then be stored in a phosphate buffered saline (PBS) solution for 1 week and then inoculated with the cultured bacterial isolate from an immature tooth with necrotic pulp. The specimens will be incubated for three weeks to permit adequate formation of a biofilm. The biofilm will be detached, diluted and spirally plated onto blood agar plates and incubated for a total of 48 hours in 5-percent CO2 at 37°C. The number of CFUs/mL will be counted using an automated colony counter. A two way ANOVA and Fisher’s Protected Least Significant Differences test using 5-percent significance level will be used to evaluate the resulting data. Expected outcome: A residual antibacterial effect will be observed on radicular dentin samples when treated with radiopaque DAP. Conclusion: Using a radiopaque DAP that provides residual antibacterial effects, further awareness into regenerative endodontic procedures will be gained leading to alterations in treating such cases. / 2020-06-30

Natriumpicosulfat-Tropfen erlauben eine sehr genaue Dosierung. Die randomisierte, plazebokontrollierte, doppelblinde cross-over Studie mit 20 gesunden Probanden wurde durchgeführt, um weitere Informationen sowohl über eine Dosis-Wirkungsbeziehung als auch über dosisabhängige pharmakokinetische Parameter und Verträglichkeit zu erhalten. Das Ziel war die Messung der Kolontransitzeit und der Zeit bis zum Wirkungseintritt und der Überprüfung, ob es eine Beziehung zwischen den kinetischen und dynamischen Parametern gibt. Die Probanden nahmen jeweils 5, 10 oder 15 mg Natriumpicosulfat-Tropfen oder Plazebo in einer oralen Einmaldosis. Die Kolontransitzeit, die Zeit bis zum Wirkungseintritt, die Urinausscheidung von BHPM (aktiver Metabolit von Natriumpicosulfat) und die Verträglichkeit wurden untersucht. Die mittlere Kolontransitzeit und die mittlere Zeit bis zum Wirkungseintritt waren nach Einnahme von 5, 10 und 15 mg Natriumpicosulfat-Tropfen im Vergleich zu Plazebo signifikant verkürzt. Es konnte jedoch keine eindeutige Dosis-Wirkungsbeziehung gefunden werden. Die Ausscheidung von BHPM sinkt mit Erhöhung der Natriumpicosulfatdosis und einer beschleunigten Kolontransitzeit. Die Verträglichkeit war gut. Die Nebenwirkungen (Magenkrämpfe, Blähungen) sind das Resultat der motilitätswirksamen Eigenschaften von Natriumpicosulfat. / Sodium picosulfate drops allow a very accurate dosage. The randomized, placebo-controlled, double blind cross-over study in 20 healthy volunteers was to provide further information about a dose-response ratio as well as dose-dependent pharmacokinetic parameters and tolerance. The aim was to measure transit time and time to onset of action and to check whether there was a correlation between kinetic and dynamic data. The volunteers received 5, 10 and 15 mg sodium picosulfate drops or placebo orally in a single dose. Colon transit time, time to onset of defecation, urinary excretion of BHPM (the active principle of sodium picosulfate) and tolerability were tested. Mean transit time and mean time to onset were significantly reduced by 5, 10 and 15 mg of sodium picosulfate, compared to placebo. No clear dose-response ratio could be found. The urinary excretion of BHPM dropped with increase of administered dose and accelerated transit velocity. The tolerance was good. The adverse events (stomach cramps, flatulence) are the result of motility stimulating effect of sodium picosulfate.