Additive Manufacturing Technologies: Where Did We Start and Where Have We Landed? A Narrative Review.

Additive manufacturing (AM), also known as 3D printing, is gaining burgeoning interest among various dental disciplines. The import of this technology stems not only from its ability to fabricate different parts but from the solutions it provides for the customization and production of complex designs that other methods cannot offer-all to the end of enhancing clinical treatment alternatives. There is a wide range of AM machinery and materials available to choose from, and the goal of this review is to provide readers and clinicians with a decision tool for selecting the appropriate technology for a given application and to successfully integrate AM into the digital workflow.

Influence of different designs of bulb support structures on the accuracy and weight of 3D printed maxillary obturators. An in vitro study.

STATEMENT OF PROBLEM: Evidence is lacking on the influence of different designs of bulb support structures on the accuracy of 3-dimensional (3D) printed obturators. PURPOSE: The purpose of this in vitro study was to evaluate the influence of various infill designs (hollow, honeycomb, and gyroid) for the bulb of an obturator on the accuracy and weight of digital light projection (DLP) 3D printed maxillary obturators. MATERIAL AND METHODS: A maxillary obturator was virtually designed and used to obtain 3 digital reference files which were defined based on the design of the infill support structure within the bulb: hollow, honeycomb, and gyroid. The resultant standard tessellation language (STL) files were used to fabricate the obturators using a DLP 3D-printer in FREEPRINT denture resin material (n=10 per each group design). The fitting surfaces of all printed specimens (n=30) were digitized using a laboratory scanner, and the scan STL files were exported to the Geomagic control X program for dimensional accuracy analysis (trueness and precision) using the digital subtraction technique. One-way analysis of variance (ANOVA) was used for analysis (α=.05) RESULTS: Quantitative analysis revealed no significant difference in root mean square estimate (RMSE) values among the test groups for trueness (P=.326) and precision (P=.140). Hollow bulb design was significantly lighter in weight than both honeycomb and gyroid infill designs (P<.001). Colormaps revealed increased areas of negative deviation around the circumference of the bulb wall in the hollow design compared with both the gyroid and honeycomb groups and the close surface matching of fitting surfaces in the 3 groups. CONCLUSIONS: The lack of significant difference in accuracy among the tested groups and the significantly lighter hollow design obturator compared with honeycomb and gyroid designs favors the selection of the hollow bulb design in the digital fabrication of maxillary obturators.

Fetal and neonatal outcomes of posterior fossa anomalies: a retrospective cohort study.

The primary aim of this study was to estimate the incidence of posterior fossa anomalies (PFA) and assess the associated outcomes in King Abdulaziz Medical City (KAMC), Riyadh. All fetuses diagnosed by prenatal ultrasound with PFA from 2017 to 2021 in KAMC were analyzed retrospectively. PFA included Dandy-Walker malformation (DWM), mega cisterna magna (MCM), Blake's pouch cyst (BPC), and isolated vermian hypoplasia (VH). The 65 cases of PFA were 41.5% DWM, 46.2% MCM, 10.8% VH, and 1.5% BPC. The annual incidence rates were 2.48, 2.64, 4.41, 8.75, and 1.71 per 1000 anatomy scans for 2017, 2018, 2019, 2020, and 2021, respectively. Infants with DWM appeared to have a higher proportion of associated central nervous system (CNS) abnormalities (70.4% vs. 39.5%; p-value = 0.014) and seizures than others (45% vs. 17.9%; p-value = 0.041). Ten patients with abnormal genetic testing showed a single gene mutation causing CNS abnormalities, including a pathogenic variant in MPL, C5orf42, ISPD, PDHA1, PNPLA8, JAM3, COL18A1, and a variant of uncertain significance in the PNPLA8 gene. Our result showed that the most common PFA is DWM and MCM. The autosomal recessive pathogenic mutation is the major cause of genetic disease in Saudi patients diagnosed with PFA.

Dental Anxiety Among Physicians: Relationship with Oral Problems, Dental Visits, and Socio-Demographic Factors.

Purpose: The purpose of study was to investigate dental anxiety (DA) and its relationship with oral health problems, dental visits, and socio-demographic factors among physicians. Patients and Methods: This cross-sectional study was conducted on physicians working in Dhahran, Khobar, Dammam, and Qatif cities of the kingdom of Saudi Arabia. The study included physicians (general practitioners, residents, specialists, and consultants) working in the public and private sectors. Modified Dental Anxiety Scale and World Health Organization's Oral Health Questionnaire for Adults were used to evaluate DA, oral health problems, and dental attendance. Results: The study included data from 355 participants with a mean age of 40.13 ± 10.45 years. There were 57.2% of non-Saudi and 42.8% of Saudi participants in the study. Bad dental experience in the previous dental visit was reported by 40% of participants, which was significantly related to DA (P = 0.002). Only 9.60% of participants had no DA, whereas 41.10% demonstrated low DA, 23.4% moderate DA, 18.9% high DA, and 7% extreme DA. Common oral problems included tooth sensitivity (65.40%), tooth cavities (45.90%), bleeding gums (43.10%), and bad breath (36.90%). More than half of participants (58.3%) visited the dentist during the last year and dental pain was the most common reason for dental visits (31.3%). Saudi participants demonstrated significantly increased DA than non-Saudis (P = 0.019). DA was significantly related to tooth sensitivity (P = 0.001), tooth cavities (P = 0.002), dry mouth (P = 0.044), and bad breath (P = 0.005). The participants with difficulty in biting foods (P > 0.001) and feeling embarrassed due to the appearance of teeth (P < 0.001) demonstrated significantly higher DA. Conclusion: This sample of physicians showed a high prevalence of DA, oral problems, and dental visits due to pain. DA was significantly related to physicians' negative dental experience, tooth sensitivity, dental decay, dry mouth, and bad breath.

Influence of Fabrication Technique on Adhesion and Biofilm Formation of Candida albicans to Conventional, Milled, and 3D-Printed Denture Base Resin Materials: A Comparative In Vitro Study.

The aim of this study was to evaluate the adhesion and biofilm formation of Candida albicans (C. albicans) on conventionally fabricated, milled, and 3D-printed denture base resin materials in order to determine the susceptibility of denture contamination during clinical use. Specimens were incubated with C. albicans (ATCC 10231) for 1 and 24 h. Adhesion and biofilm formation of C. albicans were assessed using the field emission scanning electron microscopy (FESEM). The XTT (2,3-(2-methoxy-4-nitro-5-sulphophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) assay was used for the quantification of fungal adhesion and biofilm formation. The data were analyzed using GraphPad Prism 8.02 for windows. One-way ANOVA with Tukey's post hoc testing were performed with a statistical significance level set at α = 0.05. The quantitative XTT biofilm assay revealed significant differences in the biofilm formation of C. albicans between the three groups in the 24 h incubation period. The highest proportion of biofilm formation was observed in the 3D-printed group, followed by the conventional group, while the lowest candida biofilm formation was observed in the milled group. The difference in biofilm formation among the three tested dentures was statistically significant (p < 0.001). The manufacturing technique has an influence on the surface topography and microbiological properties of the fabricated denture base resin material. Additive 3D-printing technology results in increased candida adhesion and the roughest surface topography of maxillary resin denture base as compared to conventional flask compression and CAD/CAM milling techniques. In a clinical setting, patients wearing additively manufactured maxillary complete dentures are thus more susceptible to the development of candida-associated denture stomatitis and accordingly, strict oral hygiene measures and maintenance programs should be emphasized to patients.

Influence of scan technology on the accuracy and speed of intraoral scanning systems for the edentulous maxilla: An in vitro study.

PURPOSE: To compare the accuracy of three intraoral scanners in terms of trueness and precision relative to the scanner acquisition technology and scan capture mode. Scan speed of each scanner was also evaluated. MATERIALS AND METHODS: An edentulous maxillary arch was digitized (reference model) and 3D-printed using an SLA-based 3D-printer (XFAB; DWS, Italy) (n = 10). Each model was scanned using three intraoral scanners, each with different scan technologies: confocal (Trios 3; 3Shape, Copenhagen, Denmark), parallel confocal (iTero; Align Technology), and triangulation (Medit i700). Scan time and scanning accuracy (trueness and precision) were calculated using digital subtraction technique (Geomagic Control X v2020, 3DSystems, USA). One-way analysis of variance (ANOVA) test was used to detect differences in trueness, precision, and scanning time between the tested groups (p < 0.05). RESULTS: ANOVA results showed statistically significant differences in trueness, precision, and scan time among the tested groups. Confocal scanning technique (Trios 3) showed the highest trueness and precision (root mean square estimate [RMSE] 0.094 and 0.096, respectively) followed by iTero displaying parallel confocal technique (RMSE 0.113 and 0.133, respectively); the difference was not significant (p = 0.849, p = 0.488). Further, Trios showed the longest scanning time (100 s) compared to iTero and Medit i700 (p = 0.011 and 0.002, respectively). Medit i700 presenting triangulation scan technology revealed lowest trueness and precision (RMSE 0.268) (p = 0.000, p = 0.001) and fastest scan time (59 s) close to iTero (66 s) (p = 0.802). CONCLUSIONS: Scanner technology had an influence on the accuracy and scan speed of the acquired intraoral scans. The Trios 3 scanner featuring the confocal acquisition technology displayed the highest trueness, precision, and longest scan time. Medit i700 IOS with triangulation acquisition concept featured the lowest trueness, precision, and fastest scan speed. There is no ideal scanner with the best combination of accuracy and scan speed.

Does the palatal vault form have an influence on the scan time and accuracy of intraoral scans of completely edentulous arches? An in-vitro study.

PURPOSE: The purpose of this study was to evaluate the influence of different palatal vault configurations on the accuracy and scan speed of intraoral scans (IO) of completely edentulous arches. MATERIALS AND METHODS: Three different virtual models of a completely edentulous maxillary arch with different palatal vault heights-Cl I moderate (U-shaped), Cl II deep (steep) and Cl III shallow (flat)-were digitally designed using CAD software (Meshmixer; Autodesk, USA) and 3D-printed using SLA-based 3D-printer (XFAB; DWS, Italy) (n = 30; 10 specimens per group). Each model was scanned using intraoral scanner (Trios 3; 3Shape™, Denmark). Scanning time was recorded for all samples. Scanning accuracy (trueness and precision) were evaluated using digital subtraction technique using Geomagic Control X v2020 (Geomagic; 3DSystems, USA). One-way analysis of variance (ANOVA) test was used to detect differences in scanning time, trueness and precision among the test groups. Statistical significance was set at α = .05. RESULTS: The scan process could not be completed for Class II group and manufacturer's recommended technique had to be modified. ANOVA revealed no statistically significant difference in trueness and precision values among the test groups (P =.959 and P =.658, respectively). Deep palatal vault (Cl II) showed significantly longer scan time compared to Cl I and III. CONCLUSION: The selection of scan protocol in complex cases such as deep palatal vault is of utmost importance. The modified, adopted longer path scan protocol of deep vault cases resulted in increased scan time when compared to the other two groups.

Development, In-Vitro Characterization and In-Vivo Osteoinductive Efficacy of a Novel Biomimetically-Precipitated Nanocrystalline Calcium Phosphate With Internally-Incorporated Bone Morphogenetic Protein-2.

The repair of large-volume bone defects (LVBDs) remains a great challenge in the fields of orthopedics and maxillofacial surgery. Most clinically available bone-defect-filling materials lack proper degradability and efficient osteoinductivity. In this study, we synthesized a novel biomimetically-precipitated nanocrystalline calcium phosphate (BpNcCaP) with internally incorporated bone morphogenetic protein-2 (BpNcCaP + BMP-2) with an aim to develop properly degradable and highly osteoinductive granules to repair LVBDs. We first characterized the physicochemical properties of the granules with different incorporation amounts of BMP-2 using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. We evaluated the cytotoxicity and cytocompatibility of BpNcCaP by assessing the viability and adhesion of MC3T3-E1 pre-osteoblasts using PrestoBlue assay, Rhodamine-Phalloidin and DAPI staining, respectively. We further assessed the in-vivo osteoinductive efficacy in a subcutaneous bone induction model in rats. In-vitro characterization data showed that the BpNcCaP + BMP-2 granules were comprised of hexagonal hydroxyapatite with an average crystallite size ranging from 19.7 to 25.1 nm and a grain size at 84.13 ± 28.46 nm. The vickers hardness of BpNcCaP was 32.50 ± 3.58 HV 0.025. BpNcCaP showed no obvious cytotoxicity and was favorable for the adhesion of pre-osteoblasts. BMP-2 incorporation rate could be as high as 65.04 ± 6.01%. In-vivo histomorphometric analysis showed that the volume of new bone induced by BpNcCaP exhibited a BMP-2 amount-dependent increasing manner. The BpNcCaP+50 µg BMP-2 exhibited significantly more degradation and fewer foreign body giant cells in comparison with BpNcCaP. These data suggested a promising application potential of BpNcCaP + BMP-2 in repairing LVBDs.

Stain Susceptibility of 3D-Printed Nanohybrid Composite Restorative Material and the Efficacy of Different Stain Removal Techniques: An In Vitro Study.

Recent burgeoning development in material science has introduced a 3D-printable, nanohybrid composite resin restorative material. However, its performance has not yet been investigated. This study evaluates the stain susceptibility and efficacy of different stain removal techniques. A total of 120 labial veneers were fabricated using milling (n = 60) and SLA 3D-printing (n = 60). Based on the immersion media: coffee, tea and artificial saliva, each group was divided into three sub-groups (n = 20). Stain susceptibility was evaluated by calculating color difference (∆E00) at 12 and 24 days using a spectrophotometer against black and white backgrounds. Collected data were analyzed with ANOVA and Tukey's post hoc test (p < 0.05). A significant interaction effect was found between the staining mediums and fabrication methods in both black and white backgrounds (p < 0.001). 3D-printed restorations showed significantly higher stain susceptibility than milled restorations (p < 0.001). Prolonged immersion time increased the color difference in both groups. In-office bleaching was more effective in stain removal in both 3D-printed and milled restoration groups. The susceptibility of the presented novel 3D-printed restorative material to color changes in different immersion mediums was clinically not-acceptable. The clinicians might expect the need to replace the restoration after 1-2 years and thus, recommendation for the use of such a material as a permanent restoration cannot be made but rather as a long-term temporary restoration.

Influence of dental college funding and time established on the satisfaction of dental graduates with their undergraduate experience in Saudi Arabia.

OBJECTIVE: With the emergence of graduates from all government and private-funded dental colleges in Saudi Arabia (SA), it is pressing to explore the graduates' satisfaction with the dental undergraduate education and training they received. The aim of the present study was to investigate the graduates' satisfaction with their education and training according to college funding arrangements (government vs private-funded) and time since establishment (established- >15 years vs new-<15 years). METHODS: A piloted, electronic questionnaire was emailed to all the members of the Saudi Dental Society who had graduated from government and and private dental colleges in SA (2,185 registrants). RESULTS: The response rate was 36.4%, with 580 government-funded college graduates (72.9%) and 216 private college graduates (27.1%) having completed and returned the questionnaire. The distribution of participants between established and new colleges was 'established' 396 (49.8%) and 'new' 400 (50.2%). Levels of dissatisfaction were recorded for graduates from established and new, government-funded and private colleges. The levels of dissatisfaction were greater amongst the graduates of established and government-funded colleges. CONCLUSION: The findings of the present study indicate concerning levels of dissatisfaction with important aspects of dental education in SA. It is suggested that there is a pressing need for more integration of basic and clinical sciences and an emphasis on hands-on training. National coordination of arrangements for dental curricula could make a major contribution to addressing the problems identified.

A nationwide survey assessing the satisfaction of dental colleges graduates with their undergraduate experience in Saudi Arabia.

OBJECTIVE: To date, there are no publications on the Saudi graduates' perceived value of their dental curriculum. The aim of this nation-wide survey was to investigate graduates' satisfaction with specific disciplines of their dental education and training. The first part of this study addressed findings according to the respondents' gender and the number of years of postgraduate experience (Graduate-related factors). METHODS: An electronic questionnaire was emailed to registrants of the Saudi Dental Society, specifically dental interns, general dentists, and specialized dentists who graduated from private and governmental dental colleges in Saudi Arabia (n = 2185). RESULTS: The response rate was 36.4 %. The number of male respondents was (n = 352, 44.2 %), the remainder being female (n = 444, 55.8 %). The number of recent dentists (≤ 5 years since graduation) was (n = 428, 53.8 %) and experienced dentists (n = 368, 46.2 %). There were statistically significant gender variations in satisfaction levels, and among dentists with different post-graduation experiences. Although male and female dental students are taught similar curriculums and have similar graduation requirements, there were statistically significant differences in various subjects covered. Similarly, recent and experienced dentists reported statistically significant differences in satisfaction in various subjects. CONCLUSION: This study provides graduates' perspectives on the strengths and weaknesses of their dental education in Saudi Arabia. The findings help in curriculum reform and collaborations between the dental colleges nationally. Ultimately this can lead to formulating a national dental accreditation and assessment body. CLINICAL SIGNIFICANCE: The findings of this study provide graduates' perspective on the dental education received in Saudi Arabia. This will help stimulate discussion and collaboration within and amongst the colleges on improving their curriculum in this fast-paced, evolving field of dentistry.

Fracture Resistance of Three-unit Fixed Dental Prostheses Fabricated with Milled and 3D Printed Composite-based Materials.

AIM: To evaluate the fracture resistance of three-unit fixed dental prosthesis (FDP) made of composite, high-density polymers (HDP), fiber-reinforced composite (FRC), and metal-ceramic (MC) using different fabrication methods. MATERIALS AND METHODS: A typodont model was prepared to receive a three-unit FDP replacing a missing second maxillary premolar. The prepared model was digitally scanned using an intraoral scanner (Trios3, 3Shape, Denmark). In total, 60 FDPs were fabricated and divided into four groups (n = 15) according to the materials and fabrication method: the subtractive method was used for the FRC (Trilor, Bioloren, Italy) and the HDP (Ambarino, Creamed, Germany) groups; the HDP group was monolithic, whereas the FRC group was layered with a nanocomposite (G-aenial Sculpt, GC). The additive method was used for the 3D printed (3DP) nanocomposite (Irix Max, DWS, Italy) and the Cr-Co (Starbond CoS powder 30) infrastructure of the MC groups. The FDPs were adhesively seated on stereolithography (SLA) fabricated dies. All samples were subjected to thermomechanical loading and fracture testing. The data for maximum load (N) to fracture was statistically analyzed with one-way analysis of variance (ANOVA) followed by Games-Howell post hoc test (α = 0.05). RESULTS: The MC group reported the highest fracture resistance with a statistically significant difference (2390.87 ± 166.28 N) compared to other groups. No significance was noted between 3DP and HDP groups (1360.20 ± 148.15 N and 1312.27 ± 64.40 N, respectively), while the FRC group displayed the lowest value (839.07 ± 54.30 N). The higher frequency of nonrepairable failures was observed in the MC and FRC groups, while HDP and 3DP groups reported a high frequency of repairable failures. CONCLUSION: Significant differences were found in fracture resistance between the tested groups. The load-bearing capacity of the composite-based FPDs exceeded the range of maximum chewing forces. CLINICAL SIGNIFICANCE: 3D printed and milled composite-based materials might offer a suitable solution for the fabrication of FPDs.

Effect of material thickness on the fracture resistance and failure pattern of 3D-printed composite crowns.

AIM: To evaluate the fracture resistance and failure pattern of 3D-printed and milled composite resin crowns as a function of different material thicknesses. MATERIALS AND METHODS: Three typodont tooth models were prepared to receive a full coverage composite resin crown with different thicknesses (0.5, 1.0, and 1.5 mm). The prepared master casts were digitally scanned using an intraoral scanner, and the STL files were used to fabricate 60 nanocomposite crowns divided into two groups according to the material thickness (n = 10) and fabrication method: a 3D-printed group (3D) using an SLA printer with nanocomposite, and a milled group (M) using a milling machine and composite blocks. All crowns were adhesively seated on stereolithography (SLA)-fabricated dies. All samples were subjected to thermomechanical loading and fracture testing. The load to fracture [N] was recorded and the failure pattern evaluated. Data were statistically analyzed using a two-way ANOVA followed by a Bonferroni post hoc test. The level of significance was set at α = 0.05. RESULTS: The 3D group showed the highest values for fracture resistance compared with the milled group within the three tested thicknesses (P < 0.001). The 3D and M groups presented significantly higher load to fracture for the 1.5-mm thickness (2383.5 ± 188.58 N and 1284.7 ± 77.62 N, respectively) compared with the 1.0-mm thickness (1945.9 ± 65.32 N and 932.1 ± 41.29 N, respectively) and the 0.5-mm thickness, which showed the lowest values in both groups (1345.0 ± 101.15 N and 519.3 ± 32.96 N, respectively). A higher incidence of irreparable fractures was observed for the 1.5-mm thickness. CONCLUSION: 3D-printed composite resin crowns showed high fracture resistance at different material thicknesses and can be suggested as a viable solution in conservative dentistry.

Adaptation of Complete Denture Base Fabricated by Conventional, Milling, and 3-D Printing Techniques: An In Vitro Study.

AIM: The aim of this study was to compare the adaptation of complete denture base (CDB) manufactured by three different techniques: conventional, milling, and three-dimensional (3-D) printing. MATERIALS AND METHODS: A master cast was duplicated to create 60 gypsum casts. Twenty casts (n = 20) were attributed to each group. In the computer-aided design and computer-aided manufacturing (CAD/CAM) groups (milling and 3-D printing), the 40 gypsum casts reserved for these two groups were scanned. An STL file was obtained and a master CDB was designed and then fabricated according to each technique. In the conventional group, a polyvinyl siloxane putty mold was obtained from the milled CDB, and this mold was used to fabricate 20 conventional denture bases by compression molding using the silicon-gypsum technique in a bronze flask. The inner surfaces of the obtained 60 CDB were scanned and superimposed over their corresponding master cast. Deviation analyses were calculated using digital subtraction technique. Five functional areas (posterior palatal seal, anterior border seal, crest of the ridge, maxillary tuberosities, and palate) were selected to evaluate the variations in CBD adaptation. RESULTS: Based on the results and color maps of all selected regions, milling technique offers the best adaptation. The crest of ridge in the conventional technique showed the least adaptation and the posterior palatal seal in the 3-D printing technique showed the best adaptation. CONCLUSION: Within the limitations of this study, the CAD/CAM fabrication techniques seem to offer better adaptation of CDB compared to the conventional fabrication technique. Milled CDBs presented the most homogeneous distribution of adaptation, yet the 3-D printing process seems a promising techniques that needs to be addressed and perfected. CLINICAL SIGNIFICANCE: The CAD/CAM technologies can help overcome many limitations related to conventional impressions and therefore should be well investigated to improve the edentulous patient's quality of life.

Attitude and levels of awareness toward organ donation and transplantation among healthcare providers: A cross-sectional study.

End-stage organ damage is the major cause of death worldwide. The number of donors is low, and one of the challenging phases in organ donation is the availability of organ donors. There are many studies that suggest a strong correlation between knowledge and beliefs toward organ donation. A study conducted among Health-Care Providers in the Intensive Care Units at a Tertiary Center at Riyadh reported that only 57% of the health-care providers in the Intensive Care Unit were willing to donate their organs. The objective of our study was to evaluate the knowledge, attitude, and awareness of organ donation and transplantation among health-care providers at different hospitals around the Kingdom of Saudi Arabia. The data of this cross-sectional descriptive study were collected between February and July 2018 in different hospitals all around the Kingdom of Saudi Arabia. The investigators formulated a questionnaire based on several published studies. Ethical approval was obtained from the Unit of Biomedical Ethics, Research Committee at King Abdul Aziz University. Of the 241 participants, 130 (53.9%) were female. In addition, 110 (45.6%) of them were medical residents. Moreover, 224 (92.9%) participants were aware of the concept of organ donation. The overall level of knowledge is good (55.2%).The study showed 62.2% have participated in the organ donation program for their close relatives only. In conclusion, the level of perception and knowledge about organ donation among health-care providers was inadequate, although they showed positive attitudes toward this issue.

Vitex agnus-castus safeguards the lung against lipopolysaccharide-induced toxicity in mice.

Vitex agnus-castus (VAC, Verbenaceae) is widely used in Chinese traditional medicine as an antiinflammatory agent. This study aimed to explore the efficacy of the VAC extract to protect against lipopolysaccharide (LPS)-induced acute lung injury. The results have shown that VAC had a potent protective activity against LPS-induced acute lung damage. It significantly decreased pulmonary edema as there was a significant decrease in lung wet/dry ratio and in protein content. VAC also decreased the lactate dehydrogenase's activity in the bronchoalveolar fluid. VAC ameliorated LPS-induced inflammatory cells infiltration into the lung tissue and reversed the histopathological lesions of the lung. Furthermore, VAC counteracted LPS-induced oxidative stress as it attenuated the lipid peroxidation marker, malondialdehyde, in the lung. VAC increased the antioxidant activity as evident by elevated superoxide dismutase activity and increased reduced glutathione content in the lung tissue. Collectively, VAC has a protective activity against LPS-induced acute lung damage through its antioxidant potential. PRACTICAL APPLICATIONS: Vitex agnus-castus has been used in various traditional medicines for treating various ailments as digestive complains, acne, rheumatic pains, menstrual irregularities, premenstrual syndrome, infertility, and hyperprolactinemia. Its leaves are used as a spice and the fruits are used as a substitute for pepper. VAC food supplements are used by women against psychic and somatic premenstrual symptoms. The findings of this study can demonstrate the potent protective activity of the VAC extract against LPS-induced acute lung damage due to its antioxidative effects. Therefore, VAC could be developed as a health functional food to improve acute lung damage and many diseases caused by oxidative damage.

Three-dimensional evaluation of marginal and internal fit of 3D-printed interim restorations fabricated on different finish line designs.

PurposeTo evaluate the influence of fabrication method and finish line design on marginal and internal fit of full-coverage interim restorations. MethodsFour typodont models of maxillary central-incisor were prepared for full-coverage restorations. Four groups were defined; knife-edge (KE), chamfer (C), rounded-shoulder (RS), rounded-shoulder with bevel (RSB). All preparations were digitally scanned. A total of 80 restorations were fabricated; 20 per group (SLA/3D-printed n=10, milled n=10). All restorations were positioned on the master die and scanned using micro-computed tomography. The mean gaps were measured digitally (ImageJ). The results were compared using MANOVA (α=.05). ResultsInternal and marginal gaps were significantly influenced by fabrication method (P=.000) and finish-line design (P=.000). 3D-Printed restorations showed statistically significant lower mean gap compared to milled restorations at all points (P=.000). The mean internal gap for 3D-printed restorations were 66, 149, 130, 95µm and for milled restorations were 89, 177, 185, 154µm for KE, C, RS, RSB respectively. The mean absolute marginal discrepancy in 3D-printed restorations were (30, 41, 30, 28µm) and in milled restorations were (56, 54, 52, 38µm) for KE, C, RS, RSB respectively. ConclusionsThe fabrication methods showed more of an influence on the fit compared to the effect of the finish-line design in both milled and printed restorations. SLA-printed interim restorations exhibit lower marginal and internal gap than milled restorations. Nonetheless, for both techniques, all values were within the reported values for CAD/CAM restorations. Significance3D-printing can offer an alternative fabrication method comparable to those of milled restorations.

3D-printing zirconia implants; a dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs.

PURPOSE: The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. MATERIALS AND METHODS: A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°(Vertical), 45° (Oblique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. RESULTS: The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2MPa) and 90° (866.7MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196nm to 3.3µm. The mean Ra (arithmetic mean roughness) value of 1.59µm (±0.41) and Rq (root mean squared roughness) value of 1.94µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. CONCLUSIONS: DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects.

Additive Manufacturing Techniques in Prosthodontics: Where Do We Currently Stand? A Critical Review.

PURPOSE: The aim of this article was to critically review the current application of additive manufacturing (AM)/3D-printing techniques in prosthodontics and to highlight the influence of various technical factors involved in different AM technologies. MATERIALS AND METHODS: A standard approach of searching MEDLINE, EMBASE, and Google Scholar databases was followed. The following search terms were used: (Prosth* OR Restoration) AND (Prototype OR Additive Manufacture* OR Compute* OR 3D-print* OR CAD/CAM) AND (Dentistry OR Dental). Hand searching the reference lists of the included articles and personal connections revealed additional relevant articles. Selection criteria were any article written in English and reporting on the application of AM in prosthodontics from 1990 to February 2016. RESULTS: From a total of 4,290 articles identified, 33 were seen as relevant. Of these, 3 were narrative reviews, 18 were in vitro studies, and 12 were clinical in vivo studies. Different AM technologies are applied in prosthodontics, directly and indirectly for the fabrication of fixed metal copings, metal frameworks for removable partial dentures, and plastic mock-ups and resin patterns for further conventional metal castings. Technical factors involved in different AM techniques influence the overall quality, the mechanical properties of the printed parts, and the total cost and manufacturing time. CONCLUSION: AM is promising and offers new possibilities in the field of prosthodontics, though its application is still limited. An understanding of these limitations and of developments in material science is crucial prior to considering AM as an acceptable method for the fabrication of dental prostheses.

Build Angle: Does It Influence the Accuracy of 3D-Printed Dental Restorations Using Digital Light-Processing Technology?

PURPOSE: The aim of this study was to evaluate the effect of the build orientation/build angle on the dimensional accuracy of full-coverage dental restorations manufactured using digital light-processing technology (DLP-AM). MATERIALS AND METHODS: A full dental crown was digitally designed and 3D-printed using DLP-AM. Nine build angles were used: 90, 120, 135, 150, 180, 210, 225, 240, and 270 degrees. The specimens were digitally scanned using a high-resolution optical surface scanner (IScan D104i, Imetric). Dimensional accuracy was evaluated using the digital subtraction technique. The 3D digital files of the scanned printed crowns (test model) were exported in standard tessellation language (STL) format and superimposed on the STL file of the designed crown [reference model] using Geomagic Studio 2014 (3D Systems). The root mean square estimate (RMSE) values were evaluated, and the deviation patterns on the color maps were further assessed. RESULTS: The build angle influenced the dimensional accuracy of 3D-printed restorations. The lowest RMSE was recorded for the 135-degree and 210-degree build angles. However, the overall deviation pattern on the color map was more favorable with the 135-degree build angle in contrast with the 210-degree build angle where the deviation was observed around the critical marginal area. CONCLUSIONS: Within the limitations of this study, the recommended build angle using the current DLP system was 135 degrees. Among the selected build angles, it offers the highest dimensional accuracy and the most favorable deviation pattern. It also offers a self-supporting crown geometry throughout the building process.