Efficacy of Sterilisation Methods and Their Effect on Enamel Demineralisation

Abstract

The aim of this project was to determine the effectiveness of sterilisation methods for dental enamel for use in intra–oral cariogenicity tests, and their possible effect on the degree of demineralisation of enamel. Bovine incisors were cut vertically into five portions and each assigned to one of five groups. Group 1 was used as a control while the other four groups were subjected, respectively, to gamma irradiation (≅25kGy), steam autoclaving (121°C for 15min), sodium hypochlorite (12% w/v for 24h) and povidone–iodine (7.5% w/v for 24h). Total viable counts of microorganisms remaining following sterilisation of the specimens were performed following incubation of the specimens for 24h at 37°C. Caries–like lesions were produced in each specimen using an acidic buffer solution (pH4.5). Sections were cut from each specimen, ground to 80–μm thickness, and microradiographed. Mineral loss and lesion depth were quantified using transverse microradiography. Statistical analysis was by ANOVA. Dunnett's and Tukey's tests. Microbial growth (Staphylococcus aureus and bacilli) was observed only in control specimens in both brain heart infusion broth and on blood agar plates. The sterilisation methods affected the enamel surface as follows: gamma irradiation (cream discolouration), NaOCl (bleaching), and povidone–iodine (white spot–like lesion). Compared with the control, there was no significant difference in mineral loss and lesion depth with any of the groups, but the numerical values of mineral loss and lesion depth in groups can be ranked as follows: gamma irradiation <povidone–iodine <control <autoclave <NaOCl. In conclusion, the four sterilisation methods were all effective to sterilise enamel, but gamma irradiation proved the most acceptable method for enamel to be used in cariogenicity tests having the least adverse effect.

Sterilization of extracted human teeth: A comparative analysis

“…6 However, such a set-up is lacking in various institutions. 7,8 NaOCl subsonic agitation causes more effective reduction in bacterial load in the root canal as compared to NaOCl irrigation alone.…”

Assessment of the effects of decontamination and storage methods on the structural integrity of human enamel

“…This solution showed some instability in the tests and different storage times, which seems to agree with the findings shown in the scientific literature 14,15 . Gamma irradiation is an effective method for tooth decontamination 5,24 but has an unfavorable cost-benefit ratio for its application in this type of research. Bovine enamel specimens were disinfected by microwave irradiation without prejudice to the property of hardness 25 and other properties, such as laser fluorescence and the profilometry should be analyzed in future studies.…”

“…Teeth can be considered a potential source of cross infection and contamination 3,4 , and efficient methods of decontamination should be adopted prior to their use, in addition to storage conditions that allow the maintenance of their physical properties [5][6][7] . In order to preserve teeth, a variety of storage methods have been used, including chloramines, formalin, sodium hypochlorite, thymol, alcohol, glutaraldehyde 8 and the autoclaving process 3,4 .…”

“…The majority of cariogenicity and erosive tests are conducted intraorally in an effort to use the natural environment of the tooth and in situ conditions [9][10][11] , consequently, in many experiments enamel specimens from human or bovine sources find their way into the volunteer's mouth 5 .…”

Estudo in situ da resistência à desmineralização do esmalte dental submetido à irradiação com laser Er,Cr:YSGG associada ao uso de produtos fluoretados

“…Dentre as técnicas existentes para utilização em tecidos duros, a esterilização por radiação gama, além de ser segura do ponto de vista de redução de microrganismos, não interfere na microdureza de superfície [Chandler, 1990;Amaechi et al, 1998. Foi previamente relatado na literatura [Bachmann & Zezell, 2005] que a dose de irradiação com Co 60 até 25 kGy não causa alteração na microdureza de superfície, apenas causando uma alteração cromática em função da deterioração de material orgânico presente no esmalte dentário, principalmente na forma de proteínas adsorvidas na superfície (menos de 3%), e também não parece interferir na formação de lesões de cárie A análise da MDS Final (pós irradiação gama) foi realizada a partir da borda selecionada quando foi realizada a MDS Inicial.…”