Background: Due to advances in digital technology, it is possible to obtain digital dental models through intraoral scanning. The stereolithographic data collected from the scanner can subsequently be printed into a three-dimensional dental model in resinic material. However, the accuracy between digital dental models and printed dental models needs to be evaluated since it might affect diagnosis and treatment planning in orthodontic treatment. This study aimed to evaluate the accuracy of digital models scanned by a Trios intraoral scanner and three-dimensional dental models printed using a Formlabs 2 3D printer in linear measurements and Bolton analysis. Methods: A total of 35 subjects were included in this study. All subjects were scanned using a Trios intraoral scanner to obtain digital study models. Stereolithographic data from previous scanning was printed using a Formlabs 2 3D printer to obtain printed study models. Mesiodistal, intercanine, intermolar, and Bolton analysis from all types of study models were measured. The intraclass correlation coefficient was used to assess intraobserver and interobserver reliability. All data were then statistically analyzed. Results: The reliability tests were high for both intraobserver and interobserver reliability, which demonstrates high reproducibility for all measurements on all model types. Most of the data compared between study models showed no statistically significant differences, though some data differed significantly. However, the differences are considered clinically insignificant. Conclusion: Digital dental models and three-dimensional printed dental models may be used interchangeably with plaster dental models for diagnostic and treatment planning purposes. Keywords: Accuracy, 3D printing, digital dental model, printed dental model.

Nickel and chromium ion release from stainless steel bracket on immersion various types of mouthwashes Abstract. The stainless steel bracket is widely used in orthodontics because of its mechanical properties, strength, and good biocompatibility. However, under certain conditions, it can be susceptible to corrosion. Studies have reported that the release of nickel and chromium ions because of corrosion can cause allergic reactions in some individuals and are mutagenic. The condition of the oral environment can lead to corrosion, and one factor that can alter the oral environment is mouthwash. The aim of this study was to measure the nickel and chromium ions released from stainless steel brackets when immersed in mouthwash and aquadest. The objects consisted of four groups of 17 maxillary premolar brackets with .022 slots. Each group was immersed in a different mouthwash and aquadest and incubated at 37 °C for 30 days. After 30 days of immersion, the released ions were measured using the ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). For statistical analysis, both the Kruskal-Wallis and Mann-Whitney tests were used. The results showed differences among the four groups in the nickel ions released (p < 0.05) and the chromium ions released (p < 0.5). In conclusion, the ions released as a result of mouthwash immersion have a small value that is below the limit of daily intake recommended by the World Health Organization.

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Objective: The prevalence of enamel demineralization among patients after orthodontic treatment is about 50%, which begins with the formation of white spot lesions. The presence of these lesions causes esthetic problems. The aim of this study was to quantify the color changes in post-debonding white spot lesions after microabrasion technique with fluoride and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application. Materials and Methods:This study used 42 first premolar teeth that had been extracted, then were soaked for 96 h in a demineralization solution (pH 4, 37°C) to form an artificial white spot lesions. Samples were randomly divided into three treatment groups (n=14): (A) Microabrasion technique only; (B) microabrasion technique with 10% CPP-ACP paste application; and (C) microabrasion technique with 1.23% APF gel application. All groups were assigned to pH cycling for 10 days. The color change was determined using spectrophotometer at 3 different time points, which were measured before and after production of the artificial white spot lesions, and after the artificial white spot lesions were treated. Results:This study showed that there was a significant difference in the color of the artificial white spot lesions after microabrasion technique with CPP-ACP application. Conclusion:Microabrasion technique with CPP-ACP application was giving better result in changing the color of white spot lesions than only microabrasion technique and microabrasion technique with fluoride application.

Objective: The present study aimed to compare the efficacy of two disinfectants against Gram-positive bacteria, particularly Streptococcus mutans,for use as a disinfectant for dental retainers.Methods: In total, 35 thermoplastic retainers in this study were categorized into three immersion groups: control group; mouthwash group, usingchlorhexidine 0.1%; and denture cleanser tablet group. The retainers were worn for 15 days, and Gram-positive bacteria were enumerated before andafter the retainers were immersed.Results: We found a significant difference in bacterial numbers between the two disinfectant groups and the non-disinfectant or control group. Bothdisinfectant groups had decreased numbers of Gram-positive bacteria.Conclusions: Disinfectant use is effective in decreasing the load of Gram-positive bacteria on thermoplastic retainers.