Učinak sredstva za čišćenje zubne proteze na fizikalno-mehanička svojstva termoplastičnoga poliamidnog materijala za bazu proteze za injekcijsko prešanje: preliminarno istraživanje

Objectives: This study aimed to assess the color stability, surface roughness, and flexural properties of the injection-molded thermoplastic polyamide Vertex ThermoSens denture base resin following a 3-minute immersion in Polident 3-minute denture cleanser. Methods: Sixty specimens (Vertex ThermoSens) were processed and divided into two main groups (n = 30) based on the type of test. Group 1 was further subdivided into two subgroups (n = 15): the control group immersed in distilled water (G1DW) and the test group immersed in Polident cleanser solution (G1PD). Group 2 was divided into three subgroups: a non-immersed group (G2None), a group immersed in distilled water (G2DW), and a group immersed in Polident cleanser solution (G2PD). Color change (∆E) and surface roughness measurements were conducted for group 1, and flexural modulus (E) test was performed for group 2. The CIE Lab* formula was utilized to calculate ∆E. An optical 3D surface analyzer and a three-point bending test were employed for surface roughness and E assessments, respectively. Data were subjected to statistical analysis using a paired-sample t-test for differences within each group before and after immersion. Furthermore, independent-sample t-tests and one-way ANOVA were conducted to analyze differences between groups. A significance level of P 0.05) ∆E in all color components (L*, a*, b*) after immersion in distilled water. However, after immersion in the denture cleanser, only the L* component exhibited a statistically significant ∆E (P = 0.002), which was slight in magnitude. Additionally, a significant difference was found in the ∆E between G1DW and G1PD, with G1PD showing a higher change (P = 0.007). A significant increase in surface roughness after immersion was observed in G1PD (P = 0.017), with a notable difference between G1DW and G Conclusion: Denture cleansers have the potential to modify the properties of thermoplastic polyamide resin. Further research is needed to explore the clinical implications of these observed changes on denture performance. 1PD. However, the E remained unaffected (P = 0.537).Svrha istraživanja: Svrha ovog istraživanja bila je procijeniti postojanost boje, hrapavost površine i svojstva savijanja termoplastične poliamidne smole za proteze za injekcijsko prešanje Vertex ThermoSens poslije trominutnog uranjanja u sredstvo za čišćenje proteza Polident. Materijali i metode: Obrađeno je šezdeset uzoraka (Vertex ThermoSens) i podijeljeno u dvije glavne skupine (n = 30) na temelju vrste ispitivanja. Skupina 1 dalje je podijeljena u dvije podskupine (n = 15): kontrolnu skupinu uronjenu u destiliranu vodu (G1DW) i testnu skupinu uronjenu u otopinu za čišćenje Polident (G1PD). Skupina 2 podijeljena je u tri podskupine: skupinu koja nije uronjena (G2None), skupinu uronjenu u destiliranu vodu (G2DW) i skupinu uronjenu u otopinu za čišćenje Polident (G2PD). Mjerenja promjene boje (∆E) i hrapavosti površine provedena su za skupinu 1, a ispitivanje modula savijanja (E) za skupinu 2. Za izračun ∆E korištena je formula CIE Lab*. Optički 3D površinski analizator i test savijanja u trima točkama korišteni su za procjenu hrapavosti površine, odnosno E. Podatci su podvrgnuti statističkoj analizi korištenjem t-testa uparenih uzoraka za razlike unutar svake skupine prije i poslije uranjanja. Nadalje, t-testovi neovisnog uzorka i jednosmjerna ANOVA obavljeni su da bi se analizirale razlike između skupina. Uzeta je u obzir razina značajnosti P 0,05) ∆E u svim komponentama boje (L*, a*, b*) poslije uranjanja u destiliranu vodu. Međutim, poslije uranjanja u sredstvo za čišćenje proteze, samo je komponenta L* pokazala statistički značajan ∆E (P = 0,002) koji je bio male veličine. Osim toga, pronađena je značajna razlika u ∆E-u između G1DW-a i G1PD-a, pri čemu je G1PD pokazao veću promjenu (P = 0,007). Značajno povećanje hrapavosti površine poslije uranjanja uočeno je kod G1PD-a (P = 0,017), uz primjetnu razliku između G1DW-a i G1PD-a. No E je ostao nepromijenjen (P = 0,537). Zaključak: Sredstva za čišćenje proteza mogu modificirati svojstva termoplastične poliamidne smole. Potrebna su daljnja istraživanja kako bi se istražile kliničke implikacije tih uočenih promjena na kvalitetu proteze

Assessment of Natural Radioactivity Levels and Potential Radiological Risks of Common Building Materials Used in Bangladeshi Dwellings.

The concentrations of primordial radionuclides (226Ra, 232Th and 40K) in commonly used building materials (brick, cement and sand), the raw materials of cement and the by-products of coal-fired power plants (fly ash) collected from various manufacturers and suppliers in Bangladesh were determined via gamma-ray spectrometry using an HPGe detector. The results showed that the mean concentrations of 226Ra, 232Th and 40K in all studied samples slightly exceeded the typical world average values of 50 Bq kg(-1), 50 Bq kg(-1) and 500 Bq kg(-1), respectively. The activity concentrations (especially 226Ra) of fly-ash-containing cement in this study were found to be higher than those of fly-ash-free cement. To evaluate the potential radiological risk to individuals associated with these building materials, various radiological hazard indicators were calculated. The radium equivalent activity values for all samples were found to be lower than the recommended limit for building materials of 370 Bq kg(-1), with the exception of the fly ash. For most samples, the values of the alpha index and the radiological hazard (external and internal) indices were found to be within the safe limit of 1. The mean indoor absorbed dose rate was observed to be higher than the population-weighted world average of 84 nGy h(-1), and the corresponding annual effective dose for most samples fell below the recommended upper dose limit of 1 mSv y(-1). For all investigated materials, the values of the gamma index were found to be greater than 0.5 but less than 1, indicating that the gamma dose contribution from the studied building materials exceeds the exemption dose criterion of 0.3 mSv y(-1) but complies with the upper dose principle of 1 mSv y(-1)

Radiation hazard indicators for ²²⁶Ra, ²³²Th and ⁴⁰K radionuclides in the various building materials under study.

<p>AM±SD denotes arithmetic mean±standard deviation.</p><p>Radiation hazard indicators for ²²⁶Ra, ²³²Th and ⁴⁰K radionuclides in the various building materials under study.</p

Comparison of the average activity concentrations of the studied building materials with other published data.

<p>Comparison of the average activity concentrations of the studied building materials with other published data.</p

Dose contribution due to the content of ²²⁶Ra, ²³²Th and ⁴⁰K in building materials to the inhabitants.

<p>Dose contribution due to the content of ²²⁶Ra, ²³²Th and ⁴⁰K in building materials to the inhabitants.</p