Evaluation of the pit and fissure system in primary and permanent molars with micro-computed tomography and 3D printing.

This study aimed to characterize the anatomical and physiological features of pits and fissures in primary and permanent molars by microtomographic (micro-CT) examination and three-dimensional (3D) printing. The occlusal surfaces of 84 primary molars and 60 permanent third molars were examined. The samples were scanned with micro-CT and the occlusal surface separated. The areas of the crown, its occlusal part, and fissures and pits were calculated. Digital impression of the occlusal surface was created and 3D printed. The frequency of different fissure types was determined by direct observation. Data were subjected to statistical analysis using Mann-Whitney U Test and chi-square test (p < 0.05). There was statistically significant difference between the ratio of occlusal surface and the crown area for the molars in primary and permanent dentitions (24.78% and 28.85% respectively, p < 0.05). In terms of the percentage ratio of the fissure area to the occlusal surface (24.24% and 22.30%) and the fissure area to the crown (6.02% and 6.52%), no significant difference was observed (p > 0.05). V-shaped fissures were predominant in both primary and permanent teeth, with a higher occurrence in primary dentition (59.48%, p < 0.05). Permanent molars exhibited a higher prevalence of I-type and U-type fissure configurations compared to primary molars (p < 0.05), with I-type fissures being the least common in primary molars. In both dentitions there was no statistically significant difference in the prevalence of IK-configuration (p > 0.05). The fissure depth was significantly greater in permanent molars than primary molars (p < 0.05). In conclusion, this study revealed remarkable diversity in fissure morphology among primary and permanent molars.

Virtual surgical planning and use of a 3D-printed, patient-specific reduction system for minimally invasive plate osteosynthesis of diaphyseal tibial fractures in dogs: A historic case control study.

OBJECTIVE: To compare the efficacy and clinical outcomes of computed tomography (CT)-based virtual surgical planning (VSP) and a three-dimensional (3D)-printed, patient-specific reduction system to conventional indirect reduction techniques for diaphyseal tibial fractures stabilized using minimally invasive plate osteosynthesis (MIPO) in dogs. STUDY DESIGN: A prospective clinical study with a historic control cohort. SAMPLE POPULATION: Dogs undergoing MIPO stabilization of diaphyseal tibial fractures using a custom 3D-printed reduction system (3D-MIPO; n = 15) or conventional indirect reduction techniques (c-MIPO; n = 14). METHODS: Dogs were prospectively enrolled to the 3D-MIPO group and CT scans were used to design and fabricate a custom 3D-printed reduction system to facilitate MIPO. Medical records were searched to identify dogs for the c-MIPO group. Pre-, intra- and postoperative parameters were compared between groups. RESULTS: The duration from presentation until surgery was 23 h longer in the 3D-MIPO group (p = .002). Fewer intraoperative fluoroscopic images were acquired (p < .001) and mean surgical duration was 34 min shorter in the 3D-MIPO group (p = .014). Median postoperative tibial length, frontal alignment, and sagittal alignment were within 4 mm, 3° and 3°, respectively, of the contralateral tibia in both groups and did not differ between reduction groups (p > .1). Postoperative complications occurred in 27% and 14% of fractures in the 3D-MIPO and c-MIPO groups, respectively. CONCLUSION: Both reduction methods yielded comparable results. Although the preoperative planning and guide preparation was time consuming, surgery times were shorter and fluoroscopy use was less in the 3D-MIPO group. CLINICAL SIGNIFICANCE: VSP and the custom 3D-printed reduction system facilitated efficient MIPO.

New solutions in transplantology and graft acquisition.

In view of rapid advancements in the field of transplantology, emerging solutions in tissue procurement for transplantation became a crucial area of research. Tissue transplantation plays a notable role in improving the quality of life for patients afflicted with various ailments, and the increasing number of transplants necessitates the exploration of innovative procurement methods. This study examines a new direction in transplantology, placing focus on innovative approaches to tissue procurement and discussing the commonly used method of "ex mortuo," i.e., retrieving organs from deceased donors. Given the growing demand for organs, the paper discusses the innovative approach slowly emerging as 3D bioprinting. The paper discusses the key challenges associated with the use of this method in transplantology, including issues of biocompatibility, vascularization, and integration with the immune system. The paper also discusses the latest scientific achievements in the field, such as the first transplants of bioprinted organs, demonstrating the practical application of this technology in medicine. It is also the analysis of the ethical, social, and legal aspects related to these new solutions. The article provides a comprehensive overview of the latest trends in transplantology and presents a holistic view of the current state of knowledge and prospects for development in this pivotal area of medicine.

Manufacturing Process of Prostheses Using Semirigid Molds by Additive Technologies.

Prostheses play a vital role in restoring function and mobility to individuals with physical disabilities. This study focuses on the procedure to create customized prostheses using semirigid molds obtained from additive technologies. This innovative methodology aims to improve the fit and comfort of prostheses.The manufacturing process of prostheses using semirigid molds combined with additive technologies involves several key phases. These include the use of computed tomography (CT) of the affected area, computer-aided design, and the production of custom mold models.This study introduces the main production phases of customized prostheses, based on the strategy that involves the manufacturing of semirigid molds, by additive manufacturing (AM). This approach improves fit, comfort, and integration of prostheses into patients' daily lives. In particular, prostheses for cranioplasty are described in this study.

Astragalus polysaccharide-containing 3D-printed scaffold for traumatized skin repair and proteomic study.

Astragalus polysaccharide-containing 3D-printed scaffold shows great potential in traumatic skin repair. This study aimed to investigate its repairing effect and to combine it with proteomic technology to deeply resolve the related protein expression changes. Thirty SD rats were divided randomly into three groups (n = 10 per group): the sham-operated group, the model group and the scaffold group. Subsequently, we conducted a comparative analysis on trauma blood perfusion, trauma healing rate, histological changes, the expression of the YAP/TAZ signalling pathway and angiogenesis-related factors. Additionally, neonatal skin tissues were collected for proteomic analysis. The blood perfusion volume and wound healing recovery in the scaffold group were better than that in the model group (p < 0.05). The protein expression of STAT3, YAP, TAZ and expression of vascular-related factor A (VEGFA) in the scaffold group was higher than that in the model group (p < 0.05). Proteomic analysis showed that there were 207 differential proteins common to the three groups. Mitochondrial function, immune response, redox response, extracellular gap and ATP metabolic process were the main groups of differential protein changes. Oxidative phosphorylation, metabolic pathway, carbon metabolism, calcium signalling pathway, etc. were the main differential metabolic pathway change groups. Astragalus polysaccharide-containing 3D-printed scaffold had certain reversals of protein disorder. The Astragalus polysaccharide-containing 3D-printed scaffold may promote the VEGFs by activating the YAP/TAZ signalling pathway with the help of STAT3 into the nucleus, accelerating early angiogenesis of the trauma, correcting the protein disorder of the trauma and ultimately realizing the repair of the wound.

3D printed spiral tube-like cellulose scaffold for oral delivery of probiotics.

Introducing specific strains of probiotics into the gut microbiome is a promising way to modulate the intestinal microbiome to treat various health conditions clinically. However, oral probiotics typically have a temporary or limited impact on the gut microbiome and overall health benefits. Here, we reported a 3D printed cellulose-derived spiral tube-like scaffold that enabled high efficacy of the oral delivery of probiotics. Benefiting from the unique surface pattern, this system can effectively extend the retention time of loaded probiotics in the gut without invading nearby tissues, provide a favorable environment for the survival and long-term colonization of loaded probiotics, and influence the intestinal ecosystem as a dietary fiber after degradation. We demonstrate Roseburia intestinalis-loaded scaffold exerts noticeable impacts on the regulation of the gut microbiome to treat various gut-related diseases, including obesity and inflammatory bowel disease; thus, we provide a universal platform for oral delivery of probiotics.

Beyond hype: unveiling the Real challenges in clinical translation of 3D printed bone scaffolds and the fresh prospects of bioprinted organoids.

Bone defects pose significant challenges in healthcare, with over 2 million bone repair surgeries performed globally each year. As a burgeoning force in the field of bone tissue engineering, 3D printing offers novel solutions to traditional bone transplantation procedures. However, current 3D-printed bone scaffolds still face three critical challenges in material selection, printing methods, cellular self-organization and co-culture, significantly impeding their clinical application. In this comprehensive review, we delve into the performance criteria that ideal bone scaffolds should possess, with a particular focus on the three core challenges faced by 3D printing technology during clinical translation. We summarize the latest advancements in non-traditional materials and advanced printing techniques, emphasizing the importance of integrating organ-like technologies with bioprinting. This combined approach enables more precise simulation of natural tissue structure and function. Our aim in writing this review is to propose effective strategies to address these challenges and promote the clinical translation of 3D-printed scaffolds for bone defect treatment.

From imaging to personalized 3D printed molds in cranioplasty.

Cranioplasty is the surgical repair of a bone defect in the skull resulting from a previous operation or injury, which involves lifting the scalp and restoring the contour of the skull with a graft made from material that is reconstructed from scans of the patient's own skull. The paper introduces a 3D printing technology in creating molds, which are filled with polymethyl methacrylate (PMMA) to reconstruct the missing bone part of the skull. The procedure included several steps to create a 3D model in an STL format, conversion into a G-code which is further used to produce the mold itself using a 3D printer. The paper presents our initial experience with 5 patients who undergone cranioplasty utilizing 3D printed molds. Making a patient-specific model is a very complex process and consists of several steps. The creation of a patient-specific 3D model loading of DICOM images obtained by CT scanning, followed by thresholding-based segmentation and generation of a precise 3D model of part of the patient's skull. Next step is creating the G-code models for 3D printing, after which the actual models are printed using Fused Deposition Modeling printer and PLA material. All surgeries showed good match of the missing bone part and part created using 3D printed mold, without additional steps in refinement. In such a way, 3D printing technology helps in creating personalized and visually appealing bone replacements, at a low cost of the final product.

Development and validation of 3D printed anthropomorphic head phantom with eccentric holes for medical LINAC quality assurance testing in stereotactic radiosurgery.

Stereotactic Radiosurgery (SRS) for brain tumors using Medical Linear Accelerator (LINAC) demands high precision and accuracy. A specific Quality Assurance (QA) is essential for every patient undergoing SRS to protect nearby non-cancerous cells by ensuring that the X-ray beams are targeted according to tumor position. In this work, a water-filled generic anthropomorphic head phantom consisting of two removable parts with eccentric holes was developed using Additive Manufacturing (AM) process for performing QA in SRS. In the patient specific QA, the planned radiation dose using Treatment Planning System (TPS) was compared with the dose measured in the phantom. Also, the energy consistency of radiation beams was tested at 200 MU for different energy beams at the central and eccentric holes of the phantom using an ionization chamber. Experimentally examined results show that planned doses in TPS are reaching the target within a 5% deviation. The ratio of the dose delivered in the eccentric hole to the dose delivered to the central hole shows variations of less than 2% for the energy consistency test. The designed, low-cost water-filled anthropomorphic phantom is observed to improve positioning verification and accurate dosimetry of patient-specific QA in SRS treatment.

A rapid and low-cost method to fabricate well of the well (WOW) dishes with arbitrary 3D microwell shapes for improved embryo culture.

Despite its high cost, the success rate for in vitro fertilization (IVF) remains < 33% in humans, driving the need for new techniques to improve embryo culture outcomes. The well-of-the-well (WOW) culture system is a platform for in-vitro mammalian embryo culture that has been shown to enhance the developmental competence of embryos and clinical pregnancy rates in humans. However, discovery and testing of the best design for optimal embryo culture quality is hindered by the lack of a method to flexibly produce WOW dishes of various designs. Here, we present a low-cost and simple method to fabricate WOW dishes with microwells of arbitrary shapes and dimensions. We use a low-cost 3D printing service to fabricate a poly(dimethylsiloxane) (PDMS)-based WOW insert that can be paired with a standard in vitro fertilization (IVF) dish to create WOW dishes with new microwell shapes, including pyramidal and hemispherical designs. We validate the fabrication quality of the WOW inserts and demonstrate the utility of the assembled WOW dishes for observation and grading of mouse embryo quality. Moreover, our results indicate that WOW dishes with hemispherical microwells result in better culture outcomes than traditional flat-bottomed IVF dishes and those with other microwell shapes, including the semi-elliptical microwells used in commercial WOW dishes. The proposed fabrication strategy thus provides a way to rapidly fabricate and test new WOW dishes that may bolster IVF success rates.

A comparison between 3D printed models and standard 2D planning in the use of metal block augments in revision knee arthroplasty.

OBJECTIVES: The study focused on the ability to predict the need and size of femoral and tibial augmentation using standard two-dimensional (2D) templates and models created with three-dimensional (3D) printing in surgical planning. PATIENTS AND METHODS: This observational cohort study included 28 consecutive patients (22 females, 6 males; mean age: 71±7.3 years; range, 54 to 82 years) with periprosthetic joint infection recruited between March 2021 and September 2023 undergoing revision total knee arthroplasty revision (TKA). Standard planning was made using calibrated X-ray images. The 3D planning started with computed tomography scans to generate a 3D template of the distal femur and proximal tibia. The model was exported to a 3D printer to produce a patient-specific phantom. The surgery was then simulated on the 3D phantom using revision knee arthroplasty instrumentation to evaluate the appropriate augmentation to use until a correct alignment was obtained. RESULTS: Three-dimensional planning predicted the need for femoral and tibial augments in 22 (78.6%) cases at both the tibial and femoral components, while 2D planning correctly predicted the need for augmentation in 17 (60.7%) for the tibial side and 18 (64.3%) for the femoral side. The Cohen's kappa demonstrated a significant agreement between the 3D planning for the femoral metal block and the intraoperative requirement (kappa=0.553), whereas 2D planning showed only nonsignificant poor agreement (kappa=0.083). In contrast, the agreement between 2D or 3D preoperative planning for tibial augment and the intraoperative requirement was nonsignificant (kappa=0.130 and kappa=0.158, respectively). On the femoral side, 2D planning showed only a fair nonsignificant correlation (r=0.35, p=0.069), whereas 3D planning exhibited substantial agreement with the actual thickness of the implanted augment (r=0.65, p<0.001). On the tibial side, 3D and 2D planning showed substantial agreement with the actual size of implanted augments (3D planning, r=0.73, p<0.001; 2D planning, r=0.69, p<0.001). CONCLUSION: Prediction based on 3D computed tomography segmentation showed significant agreement with the intraoperative need for augmentations in revision TKA. The results suggest that planning with 3D printed models represents a stronger aid in this kind of surgery rather than standard 2D planning, providing greater accuracy in the prediction of the required augmentation in revision TKA.

Efficacy of 3D printing-assisted treatment for acetabular fractures.

OBJECTIVES: The aim of this study was to investigate the efficacy of three-dimensional (3D) printing-assisted treatment for acetabular fractures (AFs) and to compare with conventional surgical methods. PATIENTS AND METHODS: Between May 2019 and May 2022, a total of 44 patients (33 males, 11 females; mean age: 40.6±11.8 years; range, 20 to 68 years) who were diagnosed with AFs based on clinical symptoms, X-ray and computed tomography (CT) and underwent open reduction and internal fixation in Hospital of Xinjiang Production and Construction Corps were retrospectively analyzed. The patients were divided into two groups based on whether 3D printing was applied as the experimental group (n=24) and control group (n=20). In the experimental group, pelvic and acetabular data were imported into a 3D printer, and an equal-scale highly simulated model was printed using photosensitive resin as the 3D printing material. The model was used to develop more specific personalized surgical plans, to determine the optimal sequence of surgical procedures for fracture reduction, and simulate surgery in vitro. RESULTS: In the experimental group, the mean surgical duration was shorter (123.57±22.05 vs. 163.57±26.20 min, p<0.001), the mean intraoperative bleeding loss was lower (557.14±174.15 vs. 885.71±203.27 mL, p<0.001), and the frequency of intraoperative fluoroscopy was lower (8.64±1.65 vs. 12.07±2.76, p<0.001) than in the control group. No statistically significant differences were found between the two groups in the Visual Analog Scale scores after surgery or the hip function score after treatment (p>0.05). No major postoperative complications were observed in any of the patients. CONCLUSION: Compared to conventional surgical treatment, preoperative 3D printing-assisted treatment for adult patients with AFs can significantly reduce surgical duration, intraoperative bleeding loss and frequency of intraoperative C-arm fluoroscopy, reducing surgical difficulty and improving surgical safety.

Clinical significance of modified unilateral puncture percutaneous vertebroplasty guided by 3D- printed guides in the treatment of osteoporotic vertebral compression fractures: a retrospective study.

OBJECTIVE: To investigate the clinical significance of using 3D printing guides in modified unilateral puncture percutaneous vertebroplasty (PVP) for the treatment of osteoporotic vertebral compression fractures (OVCF), and to explore a new method for preventing paravertebral vein leakage during PVP in conjunction with a previous study of the optimal puncture-side bone cement/vertebral volume ratio(PSBCV/VV%). METHODS: This retrospective study analyzed 99 patients who underwent unilateral puncture PVP between January 2023 and December 2023. Patients were divided into a guide plate group (46 patients) and a conventional group (53 patients). The guide plate group underwent modified unilateral puncture PVP with the guidance of 3D printing guides, while the conventional group underwent unilateral puncture PVP using the conventional pedicle approach. The distribution of bone cement, surgical outcomes, and the occurrence of cement leakage into paravertebral veins were observed in both groups. RESULTS: The guide plate group had significantly shorter operating time and required fewer fluoroscopies compared to the conventional group. The amount of bone cement volume (BCV) used in the guide plate group was higher, but the amount of bone cement volume on the puncture side(PSBCV), the PSBCV/VV%, and the rate of paravertebral vein leakage were lower in the guide plate group compared to the conventional group (P < 0.05). Within each group, significant improvements in anterior vertebral margin height, Cobb angle, visual analog scale (VAS) score, and Oswestry Disability Index (ODI) were observed at 1 day and 1 month postoperatively compared to preoperative values (P < 0.05). CONCLUSION: Using 3D printing guides in modified unilateral puncture PVP is a safe and effective method for treating OVCF. And it has the advantages of short operation time, less fluoroscopy, even distribution of bone cement, and a low rate of paravertebral vein leakage.

Depletion Flocculation of High Internal Phase Pickering Emulsion Inks: A Colloidal Engineering Approach to Develop 3D Printed Porous Scaffolds with Tunable Bioactive Delivery.

Flocculation is a type of aggregation where the surfaces of approaching droplets are still at distances no closer than a few nanometers while still remaining in close proximity. In a high internal-phase oil-in-water (O/W) emulsion, the state of flocculation affects the bulk flow behavior and viscoelasticity, which can consequently control the three-dimensional (3D)-printing process and printing performance. Herein, we present the assembly of O/W Pickering high-internal-phase emulsions (Pickering-HIPEs) as printing inks and demonstrate how depletion flocculation in such Pickering-HIPE inks can be used as a facile colloidal engineering approach to tailor a porous 3D structure suitable for drug delivery. Pickering-HIPEs were prepared using different levels of cellulose nanocrystals (CNCs), co-stabilized using "raw" submicrometer-sized sustainable particles from a biomass-processing byproduct. In the presence of this sustainable particle, the higher CNC contents facilitated particle-induced depletion flocculation, which led to the formation of a mechanically robust gel-like ink system. Nonetheless, the presence of adsorbed particles on the surface of droplets ensured their stability against coalescence, even in such a highly aggregated system. The gel structures resulting from the depletion phenomenon enabled the creation of high-performance printed objects with tunable porosity, which can be precisely controlled at two distinct levels: first, by introducing voids within the internal structure of filaments, and second, by generating cavities (pore structures) through the elimination of the water phase. In addition to printing efficacy, the HIPEs could be applied for curcumin delivery, and in vitro release kinetics demonstrated that the porous 3D scaffolds engineered for the first time using depletion-flocculated HIPE inks played an important role in 3D scaffold disintegration and curcumin release. Thus, this study offers a unique colloidal engineering approach of using depletion flocculation to template 3D printing of sustainable inks to generate next-generation porous scaffolds for personalized drug deliveries.

3D printing for constructing biocarriers using sodium alginate/ε-poly-l-lysine ink: Enhancing microbial enrichment for efficient nitrogen removal in wastewater.

The microbial enrichment of traditional biocarriers is limited due to the inadequate consideration of spatial structure and surface charging characteristics. Here, capitalizing on the ability of 3D printing technology to fabricate high-resolution materials, we further designed a positively charged sodium alginate/ε-poly-l-lysine (SA/ε-PL) printing ink, and the 3D printed biocarriers with ideal pore structure and rich positive charge were constructed to enhance the microbial enrichment. The rheological and mechanical tests confirmed that the developed SA/ε-PL ink could simultaneously satisfy the smooth extrusion for printing process and the maintenance of 3D structure. The utilization of the ε-PL secondary cross-linking strategy reinforced the 3D mechanical structure and imparted the requisite physical properties for its application as a biocarrier. Compared with traditional sponge carriers, 3D printed biocarrier had a faster initial attachment rate and a higher biomass of 14.58 ± 1.18 VS/cm3, and the nitrogen removal efficiency increased by 53.9 %. Besides, due to the superior electrochemical properties and biocompatibility, the 3D printed biocarriers effectively enriched the electroactive denitrifying bacteria genus Trichococcus, thus supporting its excellent denitrification performance. This study provided novel insights into the development of new functional biocarriers in the wastewater treatment, thereby providing scientific guidance for practical engineering.

[3D printing navigation template assisted pedicle screw placement for the treatment of typeâ ¡old odontoid fractures].

OBJECTIVE: To compare the safety and clinical efficacy of freehand and 3D printing navigation template assisted screw placement in patients with old odontoid fractures of typeⅡ. METHODS: Total of 38 patients with old odontoid fractures of typeⅡwere treated from November 2018 to December 2022, all of which presented as chronic neck pain. According to the different methods of screw insertion into the pedicle, the patients were divided into a navigation template group and a freehand group. In the navigation template group, there were 17 patients including 9 males and 8 females with an average age of (51.30±13.20) years old, disease duration was (22.18±7.59) months. In the freehand group, there 21 patients including 7 males and 14 females with an average age of (49.46±11.92) years old, disease duration was (19.52±9.17) months. The intraoperative blood loss, operation time, and postoperative drainage output were recorded and compared between two groups. The accuracy of screw placement was evaluated by CT scan. Before operation and 1 year after operation, cervical pain was assessed by visual analogue scale(VAS), neurological changes were evaluated by the Japanese Orthopaedic Association (JOA) score, and the degree of spinal cord injury was assessed by the American Spinal Injury Association (ASIA) injury scale. RESULTS: All patients were followed up for (25.31±1.21) months. The operation time of template group (112.00±20.48) min had significantly shorter than that of the freehand group(124.29±15.24) min(P<0.05), while there were no significant differences between two groups in terms of intraoperative blood loss, postoperative drainage, and hospital stay(P>0.05). At 1 year after operation, in template group and freehand group, the VAS [(2.88±0.86), (2.90±0.83)] and JOA [(14.94±1.82), (14.62±2.19)] improved with preoperative [VAS(4.71±0.92), (4.86±0.79) and JOA (12.18±2.30), (11.95±2.31)](P<0.05), with no significant difference between two groups (P>0.05). No significant improvement was observed in ASIA grading in either group at 1 year after operation(P>0.05), and there was no significant difference between two groups(P>0.05). The template group had significantly better accuracy of screw placement in the pedicle of the axis than the freehand group (P<0.05), while no significant difference was observed between two groups in the accuracy of screw placement in the pedicle of the atlas (P>0.05). CONCLUSION: In the treatment of typeⅡold odontoid fractures with posterior pedicle screw fixation, 3D printing navigation template screw placement can significantly shorten the operation time, achieve similar clinical efficacy as free-hand screw placement, and significantly improve the accuracy of screw placement in the pedicle of the axis.

Effect of thermocycling on tensile bond strength of autopolymerized, heat-polymerized, milled, and 3D printed denture base materials bonded to 4 different denture liners: an in vitro study.

BACKGROUND: Digitally fabricated dentures may require relining due to continual alveolar ridge resorption. However, studies evaluating the tensile bond strength (TBS) of digitally fabricated dentures bonded to denture liners are lacking. This study aimed to evaluate the TBS of autopolymerized, heat-polymerized, milled, and 3D printed denture base materials bonded to 2 acrylic-based and 2 silicone-based denture liners, both before and after thermocycling. Additionally, the impact of thermocycling on the TBS were also evaluated. METHODS: The TBS of 4 different denture base materials (Palapress (PL), Vertex Rapid Simplified (VR), Smile CAM total prosthesis (SC), and NextDent denture 3D+ (ND)) bonded to 2 acrylic-based (GC Soft-Liner (GC) and Tokuyama Rebase II (RB)) and 2 silicone-based (Ufi Gel P (UP) and Sofreliner Tough M (ST)) denture liners were tested. Specimens (n = 8) were divided into non-thermocycling and thermocycling groups. Non-thermocycling specimens were tested after 24-hours water immersion, while thermocycling specimens were underwent 5000 cycle and were immediately tested. Mode of failure was examined under a stereomicroscope. Data were analyzed using 2-way ANOVA and Tukey HSD tests (α = 0.05), and independent samples t test (α = 0.05) for TBS between non-thermocycling and thermocycling groups. RESULTS: For the non-thermocycling groups, within the same denture liner material, no significant differences were found between denture base materials, except the ND + RB group, which had significantly lower TBS. For the thermocycling groups, within the same denture liner material, the TBS in the PL group exhibited the highest and the ND group exhibited the lowest. Within the same denture base material, in both non-thermocycling and thermocycling groups, the TBS in the ST group exhibited the highest; in contrast, that in the GC group exhibited the lowest. No significant differences were observed in TBS between non-thermocycling and thermocycling groups, except for denture base materials bonded to the ST group, SC + UP, and ND + UP groups. CONCLUSIONS: Milled denture base can be relined with acrylic-based or silicone-based denture liner. However, cautions should be exercised when relining 3D printed denture base. Thermocycling did not affect TBS between acrylic-based denture liners and denture bases. In contrast, it affected the bond between silicone-based denture liner and denture base.

Fracture resistance, marginal and internal adaptation of innovative 3D-printed graded structure crown using a 3D jet printing technology.

PURPOSE: This in vitro study aimed to create a graded structured dental crown using 3D printing technology and investigate the fracture resistance and the adaptation of this new design. MATERIALS AND METHODS: A dental crown with a uniform thickness of 1.5 mm was designed, and the exported stereolithography file (STL) was used to manufacture 30 crowns in three groups (n = 10), solid (SC), bilayer (BL), and multilayer (ML) crowns using  3D jet printing technology. Marginal and internal gaps were measured using the silicone replica technique. Crowns were then luted to a resin die using a temporary luting agent and the fracture resistance was measured using a universal testing machine. One-way ANOVA and Tukey post hoc tests were used to compare the fracture resistance and the adaptation of crowns at a significance level of 0.05. RESULTS: Mean marginal and internal gap of the ML group were 80 and 82 mm, respectively; which were significantly (p < 0.05) smaller than BL (203 and 183 mm) and SC (318 and 221 mm) groups. The SC group showed the highest mean load at fracture (2330 N) which was significantly (p < 0.05) higher than the BL (1716 N) and ML (1516 N) groups. CONCLUSION: 3D jet printing technology provides an opportunity to manufacture crowns in a graded structure with various mechanical properties. This study provided an example of graded structured crowns and presented their fracture resistance. SC group had the highest fracture resistance; however, ML had the best marginal and internal adaptation.

Cost and Time Reduction of Industrial Mold Design and Manufacturing by Implementing Additive Manufacturing for Premature Neonatal Prong.

INTRODUCTION: For a long time, molding was one of the most important methods of producing metal, ceramic, and polymer materials. The two essential factors in this method were always cost and time. Technology advancements have made it possible to design in 3D using a computer and additive manufacturing. This article covers methods for using 3D printers to save time and money in the process of creating the final product. The "Prong" molds for premature neonatal respiratory aid were designed and produced based on neonatologists' considerations. METHODS: The study was conducted on fifteen very low birth neonates at Alzahra Hospital in Tabriz University from September 2017 to September 2019. In the first section, we described dental plaster material for molding. When using this material, the printing material must be selected and the parameters, like melting temperature and printer speed, must be controlled to achieve acceptable quality for the final sample. CAD software can be used to print various objects if the final 3D design is appropriate. RESULTS: We used additive manufacturing technology to create a new design and successfully resolved bubble issues at a low cost through a combination of creativity and experimentation. The new mold has cavities that allow the silicon to occupy the entire space and escape any bubbles. CONCLUSION: The use of 3D printers allows us to achieve the best design for the prong mold while reducing both production costs and time. The ultimate mold made of aluminum was finally produced by the CNC machine. The final product was tested at Al-Zahra Hospital in Tabriz, Iran, and the results were satisfactory, with no reports of necrosis on the babies' noses.

3D Slicer and 3D printing localization combined with neuroendoscopic surgery for the treatment of deep cerebral cavernous hemangioma.

To explore the advantages and disadvantages of 3D Slicer reconstruction and 3D printing localization combined with transcranial neuroendoscope in the surgical treatment of deep cerebral micro cavernous hemangiomas. Method The clinical data of patients with deep cerebral micro cavernous hemangiomas treated by our hospital from June 2022 to February 2023 using 3D Slicer reconstruction and 3D printing localization technology combined with transcranial endoscopic surgery were retrospectively analyzed. A total of 5 cases with complete data were collected, including 2 males and 3 females, aged 9-59 years. All 5 patients had deep supratentorial cavernous hemangiomas with a diameter of less than 1.5 cm, and had clinical symptoms such as headache or epilepsy, and had been diagnosed by CT or MRI. Repeated bleeding from small cavernous hemangiomas in the deep brain can lead to clinical symptoms such as recurrent headache and epilepsy, and is required surgical treatment. However, cavernous hemangiomas often have smaller lesions and are difficult to locate in the deep part. Without neuronavigation, surgery can become extremely difficult. Our team's newly developed 3D Slicer reconstruction and 3D printing localization technology which could provide new options for surgical treatment of small cavernous hemangiomas or other small lesions in the deep brain, but its accuracy and safety still need to be verified by further clinical research.