Wear and Fracture Resistance of 3D-Printed Denture Teeth: An In Vitro Comparative Study.

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.

Antifungal Activities and Some Surface Characteristics of Denture Soft Liners Containing Silicon Dioxide Nanoparticles.

Objective: This study aimed at determining the influence of adding silicon dioxide nanoparticles (nano-SiO2) to soft relining materials on C. albicans adhesion, surface roughness, and contact angle. Materials and Methods: Eighty heat-polymerized acrylic resin disks were constructed and relined by using auto-polymerized acrylic soft liners (COE-SOFT, GC Co., Tokyo, Japan). The specimens were categorized into two groups according to the tests conducted. Group A was composed of 40 specimens for evaluating antifungal activity, and Group B was composed of 40 specimens for testing surface roughness and contact angle. Each group was subcategorized into four subgroups (n = 10) according to the concentration of nano-SiO2 added to the soft-liner powder: control, 0.25%, 0.5%, and 1.0% by weight. The colony forming unit (CFU) was used to assess C. albicans count. A profilometer was used to measure the surface roughness values (Ra; µm). The sessile drop method was used to evaluate the contact angle (o) by using a goniometer. Analysis of variance and Tukey's post hoc tests (α = 0.05) were used for the data analysis. Results: In comparison with the unmodified group, the 0.25% and the 0.5% nano-SiO2 groups exhibited significantly lower C. albicans counts (P < 0.001), surface roughness (P < 0.001), and contact angles (P < 0.001). The exception was the 1% group, which exhibited higher C. albicans count, surface roughness, and contact angles than lower-concentration nano-SiO2 groups; however, these values in the 1% group were still less than their respective values in the control group. Conclusion: The addition of 0.25% and 0.5% nano-SiO2 to an auto-polymerized acrylic soft liner decreased C. albicans adhesion, surface roughness, and contact angle.

Under-reported COVID-19 cases in South Asian countries.

Background: The purpose of the study was to compare  trends in the progression of COVID-19 among South Asian countries with more developed Western countries. Methods: COVID-19 data from South Asian countries were used for this observational study. Data were taken up to April 21, 2020 from the outbreak of the COVID-19. Four of the seven countries met the inclusion criteria and were included in the analysis. Results: An exponential increase in the average number of weekly cases was reported after the fifth week following the first case. The correlation between reported cases and tests was found to be strong and significant (r=0.90, p=0.037). However, on average, 315.25 tests per million population were performed, which was at least 12 times lower than the number of tests performed in countries with a large number of COVID-19 cases. Conclusions: At present, the number of confirmed cases from South Asia was found to be significantly lower than in Western countries. Hence, an increase in the strength of performing diagnostic tests is highly recommended. Strict measures are required to make the people of these countries follow the instructions of social distancing and comply with preventive measures.

Correlation between diabetes mellitus and number of restored, carious lesions and missing teeth: A retrospective radiographic evaluation.

AIM: This study aimed to evaluate the prevalence of carious, restored, and missing teeth among diabetic and non-diabetic patients who visited dental clinics in Dammam, Saudi Arabia. METHOD: This retrospective study was conducted between April and November 2018. The data collection procedure was conducted in two steps: (1) review of patient records for the demographic variables and (2) screening of digital panoramic radiographs (OPGs). The patients who visited the restorative and prosthetic clinics in the period of 2016-2017 were included in the study. RESULTS: A total of 1186 patient records and OPGs were reviewed to extract the data. The average age of the patients in the study sample was 40.96 (±16.29). The sample included 751 (63.3%) female and 435 (36.7%) male patients. Among the patients, 192 (16.2%) had diabetes mellitus and 994 (83.8%) were non-diabetic. The average numbers of fixed partial dentures and missing teeth were significantly high among diabetic patients (P < 0.001). Conversely, the average numbers of carious lesions and restored teeth were higher among the non-diabetic patients. Only the number of restored teeth was found to be significant (P < 0.001). CONCLUSION: The diabetic patients were found to be at high risk of losing teeth compared with the non-diabetic patients. The prevalence of fixed partial dentures was also higher among diabetic patients. The oral health status of dental patients with diabetes needs urgent attention to prevent these patients from having teeth loss, and it can be done by improving their oral health.

The post-pandemic era: will physical distancing be a perceived way of life?

Background: This study aimed to determine whether people living in the Eastern Region of Saudi Arabia would prefer to continue the practice of physical distancing after the coronavirus disease 2019 (COVID-19) pandemic or to return to their previous way of life. Methods: This cross-sectional study was conducted from August 2020 to October 2020 in the Eastern Region of Saudi Arabia. A pre-tested questionnaire was sent electronically through social media. Data on participants' demographics and their perspectives regarding post-pandemic physical distancing were collected. The calculated sample size was 1,066; however, the total number of responses included in the analysis was 989. Results: The average age of the participants was 31.15±11.93 years. There were 435 men and 554 women in the study. Participants showed significantly high levels of disagreement with statements indicating that they were willing to use public transportation (61%), attend social gatherings (36%), and hug relatives or colleagues (40%) after the pandemic ( p<0.001); however, 43% agreed that they would spend time with family or friends ( p<0.001). The level of education was also found to be significantly related to the responses, and the level of disagreement increased as the level of education increased ( p<0.001). Conclusions: One-third of the study participants planned to continue engaging in physical distancing even after the current pandemic. This clearly indicates that our lives are not returning to how they were before the pandemic. However, it cannot be concluded whether or not this behavior will prevail in the long run. If so, it may greatly affect some businesses and perhaps some social norms and values as well.

Concerns, perceived impact, and preparedness of oral healthcare workers in their working environment during COVID-19 pandemic.

OBJECTIVE: The aim of the study was to evaluate the oral healthcare workers' concerns, perceived impact, and preparedness in COVID-19 pandemic. METHODS: This cross-sectional study was carried out at 10 different dental hospitals in Pakistan from March to June 2020. A 35 items valid and reliable questionnaire was used to assess the concerns, perceived impact, and preparedness of oral healthcare workers (OHCW) in COVID-19 pandemic. Chi-squared test and logistic regression were used for analysis. RESULTS: A total of 583 OHCW participated in this study. The odds of having the awareness about the risk of exposure and fear of getting infected, were greater in the clinical than non-clinical OHCW (OR: 52.6; OR: 15.9). For social network concerns, the clinical OHCW were more likely to be concerned about their colleagues (OR: 6.0). The clinical OHCW have greater odds of worrying about telling the family/friends about the risk exposed to (OR: 2.55), being avoided because of the job (OR: 3.20) and more likely to be feeling stressed (OR: 4.31). Less than 50% of the participants felt that their institutions are well prepared and only 12.6% had attended an infection control training session. Most participants practiced self-preparation such as buying masks and disinfection (94.3%, 98.3%). CONCLUSION: The majority of OHCW felt concerned about their risk of exposure to infection and falling ill from exposure and infecting friends/family. There is a need for training of infection control and PPE and minimizing fear and psychological impact on OHCW should be the priority in any preparedness and planning for combating COVID-19.

Comparative evaluation of two chelating agents in collagen fiber network modification over dentinal tubules: An in vitro analysis.

OBJECTIVE: To compare effectiveness of ethylenediaminetetraacetic acid (EDTA) and citric acid in removing collagen fiber network covering dentinal tubules of human teeth. MATERIALS AND METHODS: Eighteen dentin discs were divided in three groups; Gp 1: discs received no treatment (control), Gp 2: discs etched with 17% EDTA (pH = 7.1), and Gp 3: discs etched with 6 wt% citric acid (pH = 4.0). Scanning electron microscopy (SEM) was performed to assess collagen fiber removal and X-ray diffraction (XRD) was implemented to analyse crystal peaks of discs. RESULTS: The SEM analysis demonstrated more collagen removal with EDTA treatment compared to citric acid treated specimens. Grade 6 (81% to 100% fiber removal) was mostly achieved for Gp 2 samples whereas grade 2 (1% to 20% fiber removal) was mostly achieved for Gp 3 samples and inter-group comparisons between these groups were statistically significant (p < 0.05). X-ray diffractogram of control and experimental samples demonstrated absence of calcite phase in experimental groups. The change in peak shapes and intensities were observed and citric acid treated samples revealed more intense peaks than EDTA group. CONCLUSION: Our study found 17% EDTA to be more effective in removing collagen fibers when matched with 6% citric acid.

In vitro assessment of the antifungal effects of neem powder added to polymethyl methacrylate denture base material.

BACKGROUND: Denture with antimicrobial activities is desirable to prevent Candida albican adhesion subsequently decreasing the susceptibility of denture stomatitis incidence. Azadirachta Indica, commonly known as Neem powder has antimicrobial effect but the effect of its addition to acrylic denture base on C. albicans adhesion has not been investigated. The aim of this study was determine whether adding neem powder to acrylic denture base materials could reduce Candida albicansadhesion. MATERIAL AND METHODS: One hundred and twenty acrylic resin denture specimens were fabricated and divided into heat-polymerized (n=60) and auto-polymerized (n=60) groups. Each group was further divided into 6 groups (n=10) based on the neem concentration: 0, 0.5, 1, 1.5, 2 and 2.5 wt% of the polymer. After polymerization, the specimens were polished, stored in distilled water, sonicated, sterilized, submerged in artificial saliva containing C. albicans, and finally, placed in an incubator at 37°C. Slide counting and direct culture methods were used to assess the antifungal effects of the neem addition. An analysis of variance and post hoc Tukey's test were performed for the data analysis (p≤0.05 was statistically significant). RESULTS: Based on the results, the neem addition significantly decreased the C. albicans count when compared to the control group (p≤0.05). Moreover, the count decreased as the neem concentration increased (lowest count with 2.5 wt%). CONCLUSIONS: The results suggest that adding neem powder to acrylic resin denture base materials reduces the adhesion of C. albicans; therefore, the incorporation of neem could be a possible denture stomatitis prevention method. Key words:Denture stomatitis, Candida albicans, Azadirachta indica, neem powder, denture base.

Dental caries in Arab League countries: a systematic review and meta-analysis.

OBJECTIVE: The aim of this review was to determine prevalence of dental caries in primary and permanent teeth in the 2-20-year-old population of the Arab league. METHODS: A literature search was performed on Pubmed, Summon and Google Scholar using the key words 'Dental caries', 'dmft' and 'DMFT'. A total of 293 articles were found, of which 35 passed our inclusion criteria and were included in analysis. Tables were made separately for primary and permanent teeth; the age group for primary teeth was 2-12 years and for permanent teeth 6-20 years. RESULTS: A meta-analysis was run by using data extracted from the studies included. Heterogeneity was tested by forest plot and chi-square test, and considerable heterogeneity was found. Mean decayed, missing and filled teeth (dmft) was 4.341 (95% CI 3.714, 4.969) and in permanent teeth (DMFT) was 2.469 (95% CI 2.019, 2.919) from a random effect model. Publication bias diagnostics suggested missing of four studies of primary teeth caries data and eight studies of permanent teeth caries data to obtain symmetry in the funnel plot. CONCLUSION: The incidence of caries in primary teeth was found to be high compared with caries in permanent teeth in the Arab League. This study does not provide a comprehensive picture of caries prevalence in the Arab League because in many of these countries only a few studies were performed. Therefore, these data cannot provide a complete picture of the prevalence of caries in those countries. Additional studies are needed to better evaluate the prevalence of caries in children and young adults in Arab League countries.