Cytotoxicity effect of orthodontic miniscrew-implant in different types of mouthwash: An in-vitro study.

CONTEXT: Orthodontic miniscrew implants (OMIs) are widely used as anchorage alternatives, but recent studies revealed the corrosion behavior of OMIs when they come in contact with mouthwashes. The corrosion materials that are released can cause toxicity, allergy, and mutagenicity. AIMS: This study aims to analyze the cytotoxicity effects of OMIs exposed to different types of mouthwash using human gingival fibroblast (HGFs). SETTINGS AND DESIGN: Experimental laboratory research. METHODS AND MATERIAL: Twenty-eight samples of Ti alloy OMIs immersed separately in four groups of different types of mouthwash (chlorhexidine gluconate 0.2% mouthwash (CHX), fluoridated (sodium fluoride 0.2%) mouthwash, chitosan mouthwash 1.5%, and aquadest) for 28 d. Elution of each group and the mouthwash itself were added to the cell culture and incubated for 24 h. Changes in cell viability were performed by MTT Assay. STATISTICAL ANALYSIS USED: Data were tested for normality with Shapiro-Wilk, homogeneity with Levene test, and analyzed using an independent T-test (P < 0.05). RESULTS: The differences between the cytotoxicity of the elution of MIO and the mouthwash solution itself in the group of CHX and Fluoride were statistically significant (P < 0.05). No significant differences were found in the group of chitosan and aquadest (P > 0.05). CONCLUSIONS: The 1.5% chitosan mouthwash can be offered to patients with Ti alloy-based OMIs rather than the 0.2% chlorhexidine gluconate and 0.2% sodium fluoride mouthwashes.

Accuracy of digital dental models and three-dimensional printed dental models in linear measurements and Bolton analysis.

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.

Simulation of Stress Distribution on the Upper First Molar and Alveolar Bone with the Transpalatal Arch and Upper Second Molar Using Finite Element Analysis

Abstract Objective: To evaluate the differences in the stress distribution on the upper first molar with and without transpalatal arch and a second molar when a 150 g force is applied during canine distalization using finite element analysis. Material and Methods: We constructed several models with data obtained by scanning human skulls using cone beam computed tomography. A robust three-dimensional maxillary model was then constructed by assembling the previously completed robust models of the maxilla and second molar with and without transpalatal arch, and canine distalization was simulated using a 150 g force. The data consisted of color spectrum figures representing the stress distribution Results: For the upper first molar and its alveolar bone, there was a statistically significant difference in the stress distribution between the upper first molar with transpalatal arch, the upper first molar without transpalatal arch, and the upper first molar with transpalatal arch and a second molar as reinforcement Conclusion: Stress distribution on the first molar and alveolar bone, indicated by the maximum and minimum principal stress, as well as the pressure von Mises, exhibited a similar pattern. The highest amount of stress was observed in the model of the first molar without transpalatal arch, followed by the model of the first molar with transpalatal arch and, finally, the model of the first molar with transpalatal arch and a second molar.