An Investigation on Metallic Ion Release from Four Dental Casting Alloys

Statement of Problem: Element release from dental casting alloys into the oral environment is of clinical concern and is considered to be a potential health problem to all patients.Purpose: The aim of this study was to investigate the metallic ion release of four base metal alloys.Materials and Methods: Two Ni-Cr (Minalux and Supercast) and two Co-Cr alloys (Minalia and Wironit) were examined. Nine specimens of each type were prepared in 13×11×1.4 mm dimensions and each of the four alloys (3 specimens per group) were conditioned in artificial saliva at 37 c for one, three and seven days.The conditioning media were analyzed for element-release using Inductive CoupledPlasma Atomic Emission Spectrophotometer (ICPAES). Collected data were statistically analyzed using ANOVA and Duncan multiple range test (P< 0.05).Results: The greatest amount of element release was seen after seven days (134.9 ppb Supercast, 159.2 ppb Minalux, 197.2 ppb Minalia, and 230.2 ppb Wironit). There was a significant difference between the released elements from the alloys after the three conditioning times (p<0.001).Conclusion: Element release from the studied alloys is proportional to the conditioning time. The Ni-Cr alloys tested in this investigation were more resistant to corrosion as compared to the Co-Cr alloys in artificial saliva. Supercast had the highest corrosion resistance

Developing a software for removable partial denture design: Part I: Data collection

Background and Aim: Proper designing of partial denture frameworks is the duty of dentists, but this task is often abdicated to technicians because of lack of time and experience. Computer assisted learning and designing can be used for both training dental students and helping dentists design proper frameworks. As the first step to prepare software for framework designing, this study evaluated the agreement on different framework designing principles, among prosthodontists of dental schools in Iran. &quot;nMaterials and Methods: A questionnaire consisting of 121 design rules was sent to 41 prosthodontists at seven dental schools in Iran .The percentage rate of agreement on results was used for data analysis. &quot;nResults: The percentage of rules accepted by more than 60% of the prosthodontists was 76.2%. It consisted 80% saddle rules, 76.2% rest rules, 78.4% clasp rules, 63.6% maxillary major connector&apos;s rules and 80.9% mandibular major connector rules. &quot;nConclusion: The percentage of accepted rules by Iranian prosthodontists was 76.2%. Maxillary major connectors had the least acceptance

An evaluation on the adherence of Candida albicans to different denture- base materials

The surface topography of denture base material is an important factor for the&quot;nadhesion of Candida albicans and other microorganisms.&quot;nPurpose: The aim of this study was to evaluate the adherence of Candida albicans to four types of denture&quot;nbase materials (Acropars acrylic resin, Meliodent acrylic resin, rough and smooth surfaces of Molloplast B).&quot;nMaterials and Methods: Seven blocks of two types of acrylic resins and ten blocks of silicone with one&quot;nrough and one smooth surface were made and incubated in a suspension of Candida albicans. After washing,&quot;nthe blocks were stained with acridine orange and examined under fluorescent microscope. For statistical&quot;nanalysis ANOVA and Duncan tests were used.&quot;nResults: It was observed that Candida adhesion to rough surfaces of acrylic resins and silicone was&quot;nsignificantly more than polished surfaces of acrylic resins and smooth silicone (PO.0001). However, no&quot;nstatistical significant difference was found between polished acrylic resins surfaces and smooth silicone.&quot;nConclusion: Significant differences in the adherence of Candida to the surfaces of different denture base&quot;nmaterials are due to differences in surface topography, chemical, physical and hydrophobic properties so it is&quot;nrecommended to minimize the roughness and irregularities of denture base

Brain aluminium accumulation and oxidative stress in the presence of calcium silicate dental cements

Mineral trioxide aggregate (MTA) is a calcium silicate dental cement used for various applications in dentistry. This study was undertaken to test whether the presence of three commercial brands of calcium silicate dental cements in the dental extraction socket of rats would affect the brain aluminium (Al) levels and oxidative stress parameters. Right upper incisor was extracted and polyethylene tubes filled with MTA Angelus, MTA Fillapex or Theracal LC, or left empty for the control group, were inserted into the extraction socket. Rats were killed 7, 30 or 60 days after operation. Brain tissues were obtained before killing. Al levels were measured by atomic absorption spectrometry. Thiobarbituric acid reactive substances (TBARS) levels, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were determined using spectrophotometry. A transient peak was observed in brain Al level of MTA Angelus group on day 7, while MTA Fillapex and Theracal LC groups reached highest brain Al level on day 60. Brain TBARS level, CAT, SOD and GPx activities transiently increased on day 7 and then returned to almost normal levels. This in vivo study for the first time indicated that initial washout may have occurred in MTA Angelus, while element leaching after the setting is complete may have taken place for MTA Fillapex and Theracal LC. Moreover, oxidative stress was induced and antioxidant enzymes were transiently upregulated. Further studies to search for oxidative neuronal damage should be done to completely understand the possible toxic effects of calcium silicate cements on the brain