ABSTRACT
OBJECTIVES: With advanced technology for complete denture fabrication, there is a lack of knowledge on the mechanical behavior of three-dimensional (3D) printed teeth despite the development of complete denture fabrication technologies. This study aimed to compare different types of 3D-printed teeth in terms of wear and fracture resistance in comparison to control prefabricated denture teeth. MATERIALS AND METHODS: One prefabricated tooth was selected and fixed in a resin holder and half of the tooth remained in anatomic form, while the other half was flattened for the wear test. One from each type was scanned and then printed with different resins; Asiga (DentaTOOTH, Asiga, Alexandria 2015,NSW, Australia), FormLabs (Denture Base LP, FormLabs, Berlin, Germany), and NextDent (NextDent C&B MFH, NextDent B.V., Soesterberg, the Netherlands) according to manufacturer recommendations. A total of 60 specimens (20/resin, n = 10) were thermo cycled (5,000 cycles) and wear test samples were further subjected to cyclic loading (1,70,000 cycles) in a chewing simulator machine CS-4.2 (SD Mechatronik GmbH, Germany). The fracture strength of anatomic teeth was measured using a universal testing machine (Instron model 5965, Massachusetts, United States), while Geomagic Control X software was used to assess the amount of wear of flattened teeth. Statistical analyses were performed with one-way analysis of variance with Tukey's post hoc test at significance level of α = 0.05. RESULTS: NextDent specimens showed the greatest volume loss, whereas FormLabs specimens showed the least volume loss. Comparing NextDent specimens to FromLabs specimens, FromLabs showed statistically significantly less volume loss (p < 0.001). No other group pairs differed significantly from one another in terms of volume loss (p > 0.06). CONCLUSION: 3D-printed denture teeth showed comparable strength and wear resistance with the prefabricated denture teeth and were suitable for long-term clinical usage except for NextDent that significantly showed the lowest fracture resistance.
ABSTRACT
PURPOSE: The longevity of removable prostheses is mostly influenced by the properties of the used materials. The ability of the material to withstand high occlusal loads without deformation can enhance patient satisfaction and quality of life. This in vitro study aimed to investigate the wear and fracture resistance of three-dimensional (3D)-printed teeth compared with commercially available acrylic resin teeth. MATERIALS AND METHODS: A total of 40 prefabricated acrylic teeth and 40 3D-printed teeth were prepared in two forms: anatomical for fracture resistance or flat for wear resistance (n = 10). For wear evaluation, specimens were scanned at baseline and then subjected to thermal cycling (10,000 cycles). This was followed by a chewing simulator (60,000 cycles) against either metal or natural tooth. Then, the specimens were scanned again. Wear analysis was performed by superimposing the standard tessellation language (STL) files from baseline and the final scans with the aid of GOM Inspect 2020 software. Fracture resistance was assessed with a universal testing machine at a crosshead speed of 0.5 mm/min before and after thermal cycling. Data were analyzed with two-independent t-test and two-way ANOVA (α = 0.05). RESULTS: The 3D-printed teeth showed significantly lower wear resistance than the prefabricated ones with both antagonists (metal, p = 0.049; natural tooth, p = 0.021). The fracture resistance of the 3D-printed teeth was significantly higher than that of the prefabricated teeth before thermocycling (p = 0.042). After thermal cycling, the fracture resistance of both groups was decreased with no significant differences between them (p = 0.266). CONCLUSIONS: The 3D-printed teeth showed lower wear resistance and higher fracture resistance than the prefabricated ones. Thermal cycling negatively affected the fracture resistance of 3D-printed teeth.
Subject(s)
Acrylic Resins , Quality of Life , Humans , Materials Testing , Dentures , Printing, Three-DimensionalABSTRACT
Uterine tumors resembling sex-cord tumors are a rare group of tumors with uncertain etiology and histogenesis. The sex-cord tumors are classified into two groups. The first group includes endometrial stromal tumors with foci of sex cord differentiation less than 50% while the second group is composed predominantly or exclusively by sex cord-like elements. We report the case of a middle-aged woman who presented with heavy vaginal bleeding with initial ultrasound findings suggestive of uterine leiomyoma. There was no improvement noticed after a trial of medical treatment; hence, the surgical treatment in the form of total abdominal hysterectomy was undertaken. A few weeks after the surgery, the patient presented with unexplained abdominal pain. Imaging studies demonstrated a hypermetabolic lesion in the upper part of the vagina that was suspicious for malignancy. Complete resection of the mass was performed along with para-aortic lymphadenopathy. Histopathological examination revealed a uterine tumor resembling a sex-cord tumor. Uterine tumors resembling sex-cord tumors are a unique group of uterine neoplasms that exhibits diverge clinical and biological characteristic. Surgical pathologists must recognize this rare entity and differentiate it from other lesions.
ABSTRACT
The quality of medications is important to maintain the overall health care of patients. This study aims to develop and validate a spectrophotometric method using multivariate curve resolution-alternating least squares (MCR-ALS) with correlation constraint for simultaneous resolution and quantification of selected drugs affecting the central nervous system (imipramine, carbamazepine, chlorpromazine, haloperidol, and phenytoin) in different pharmaceutical dosage forms. Figures of merit such as root-mean-square error of prediction, bias, standard error of prediction, and relative error of prediction for the developed method were calculated. High values of correlation coefficients ranged between 0.9993 and 0.9998 reflected high predictive ability of the developed method. The results are linear in the concentration range of 0.3-5 µg/mL for carbamazepine, 0.3-15 µg/mL for chlorpromazine, 0.5-10 µg/mL for haloperidol, 0.5-10 µg/mL for imipramine, and 3-20 µg/mL for phenytoin. The optimized method was successfully applied for the analysis of the studied drugs in their pharmaceutical products without any separation step. The optimized method was also compared with a reported HPLC method using Student's t test and F ratio at 95% confidence level, and the results showed no significant difference regarding accuracy and precision. The proposed chemometric method is fast, reliable, and cost-effective and can be used as an eco-friendly alternative to chromatographic techniques for the analysis of the studied drugs in commercial pharmaceutical products.
