Surface characteristics of additively manufactured CoCr and Ti6Al4V dental alloys: The effects of carbon and gold thin film coatings, and alkali-heat treatment.

This study investigates the impact of surface modifications on additively manufactured CoCr and Ti6Al4V dental alloys, focusing on surface properties. Thin film carbon (C) and gold (Au) coatings, as well as alkali-heat treatment, were applied to the high- and low-polished specimens. Scanning electron microscopy (SEM) showed that thin film coatings retained the underlying surface topography, while the alkali-heat treatment induced distinct morphological changes. Energy-dispersive x-ray spectroscopy (EDS) analysis revealed that C-coating enriched surfaces with C, and Au-coating introduced detectable amounts of Au. Nevertheless, signs of coating delamination were observed in the high-polished specimens. Alkali-heat treatment led to the formation of a sodium titanate layer on Ti6Al4V surfaces, confirmed by sodium presence and Fourier transform infrared spectroscopy (FTIR) results showing carbonate bands. Surface roughness measurements with atomic force microscopy (AFM) showed that C-coating increased surface roughness in both high- and low-polished alloys. Au-coating slightly increased roughness, except for low-polished Au-coated Ti6Al4V, where a decrease in roughness was observed compared to low-polished bare Ti6Al4V, likely due to surface defects present in the latter resulting from the additive manufacturing process. Alkali-heat treatment led to a pronounced increase in roughness for both alloys, particularly for Ti6Al4V. Both thin film coatings decreased the water contact angles in all specimens in varying magnitudes, indicating an increase in wettability. However, the alkali-heat treatment caused a substantial decrease in contact angles, resulting in a highly hydrophilic state for Ti6Al4V. These findings underscore the substantial impact of surface modifications on additively manufactured dental alloys, potentially influencing their clinical performance. RESEARCH HIGHLIGHTS: Thin film coatings and chemical/heat treatment modify the surface properties of additively manufactured dental alloys. The surfaces of the alloys get rougher and more hydrophilic after alkali-heat treatment. Thin gold coatings exhibit potential adhesion challenges.

Comparison of different 3D printers in terms of dimensional stability by image data of a dry human mandible obtained from CBCT and CT.

OBJECTIVES: To manage the mandibular traumas, for the expression of the complex anatomy or pathology in education of health sciences related branches, a model of the traumatized mandible is indispensable. For these, different 3D-print-technologies can be used. The aim of this study is, to measure how close these 3D-printed-models are to human-mandible (trueness) and the effectiveness of CT and CBCT at this point. STUDY DESIGN: One-dry-human-mandible and 10-models manufactured by five different 3D-printers in four different-kinds of additive-manufacturing technology (Fused-Deposition-Modeling (FDM), Stereolithography (SLA), Binder-jetting (BJ), Polyjet (PJ)) were used, five-anatomic-landmarks and eight-distances were measured and evaluated. Mandible's data were constructed based on DICOM-3.0 data from CBCT and CT scans. Images were opened in MIMICS (software-program). RESULTS: Study compared the devices that produced models with the same dry human-mandible. It was seen that the model with the highest margin of error (132.5 mm) was manufactured by Fused-deposition-modeling device using CT-data. In terms of distance to real-data, the model with the lowest error was generated by Binder-Jetting (ZCorp) with CBCT-data. Models produced with CBCT-data are closer to dry-human-mandible than models with CT-data. CONCLUSION: The current study shows that CBCT generates significantly better data than CT in producing mandibular models. The first choice for manufacturing of human mandible is BJ and the second choice is the technology of SLA.

The impact of print orientation on the fracture resistance and failure patterns of additively manufactured cobalt-chromium post and cores.

PURPOSE: The aim of this study was to evaluate the impact of the print orientation of direct metal laser sintering (DMLS) posts and cores on the fracture resistance and failure patterns of endodontically treated mandibular premolar teeth. MATERIALS AND METHODS: Sixty intact human mandibular premolars were endodontically treated. The teeth were then randomly divided into four groups (n = 15). Cobalt-chromium (Co-Cr) metal posts were fabricated by traditional casting (Group C), and DMLS method in 0-, 45-, and 90-degree print orientations (Group DMLS 0, Group DMLS 45, and Group DMLS 90). The posts and cores were cemented with composite resin cement and subjected to compression test at a crosshead speed of 1 mm/min. Data was analyzed by using one-way analysis of variance ANOVA and multiple comparison post hoc Tukey tests (α = 0.05). Specimens were viewed under a stereo microscope with x20 magnification to evaluate the fracture types. RESULTS: No significant differences were found among the groups tested in terms of fracture resistance (p > 0.05). Group C and Group DMLS 0 group exhibited similar fracture patterns. CONCLUSIONS: It is possible to produce post and core restorations with the DMLS technique and use them clinically.  Print orientation did not influence the fracture resistance. However, fracture patterns were different. Group C outperformed all DMLS groups in terms of fracture patterns.

Vertical Bone Augmentation With Customized CAD/CAM Titanium Mesh for Severe Alveolar Ridge Defect in the Posterior Mandible: A Case Letter.

Implant rehabilitation after implant removal is a major challenge, especially in mandibular posterior arches. This case report describes the reconstruction of a severe vertical bone defect using customized titanium mesh covered by collagen membrane and solid advanced platelet-rich fibrin, combined with autogenous bone, deproteinized bovine bone mineral, and injectable platelet-rich fibrin after implant removal caused by advanced peri-implantitis. This individualized titanium mesh may be a reliable technique for severe alveolar ridge reconstruction, with the additional benefits of reduced surgery time and a simplified operation.

Simultaneous Closure of Bilateral Cranial Defects Using Custom-Made 3D Titanium Implants: A Single Institution Series.

AIM: To investigate the outcomes of the simultaneous closure of bilateral cranial defects using custom-made three-dimensional (3D) titanium implants. MATERIAL AND METHODS: Demographic data of 26 patients with bilateral cranial defects who underwent cranioplasty using the 3D custom-made titanium implants in our clinic between 2017 and 2022 were retrospectively reviewed. Data on the area of cranium defect, the time interval between last cranial surgery and cranioplasty, postoperative complications, etiology of the cranium defect, and hospitalization of the patient were statistically evaluated. RESULTS: The incidence of bilateral cranioplasty was 19.11%. The gender distribution of patients was 4 (15.4%) female and 22 (84.6%) male, with a mean age of 29.08 ± 14.65 years. The mean defect area was 35.0 ± 19.03 and 29.24 ± 22.51 cm2 on the right and left sides, respectively. The etiology of the cranium defect was gunshot wounds in 12 patients, and 14 patients had a history of trauma-related injuries such as falls and vehicle accidents. Eight patients had a history of failed cranioplasty with autologous bone. Postoperative complications were wound dehiscence in two patients and diffuse cerebral edema in one patient. No mortality was recorded. CONCLUSION: The custom-made cranioplasty is feasible for simultaneous closure of bilateral cranial defects. Many complications can be prevented by careful preoperative evaluation before surgery and an appropriate implant selection for the patient.

Mechanical Properties and Bond Strength of Additively Manufactured and Milled Dental Zirconia: A Pilot Study.

PURPOSE: To evaluate and compare the mechanical properties and ceramic bond of additively manufactured and milled dental zirconia materials. MATERIALS AND METHODS: Disc (r = 10 mm, h = 2 mm) and bar (25 × $\ \times \ $ 4 × 1. 2 mm) shaped milled (M group) (Nacera Pearl; Doceram) and additively manufactured (AM group) (NanoParticle Jetting; XJet, Carmel 1400) zirconia specimens were prepared for 2 experimental groups. Ceramic was applied to the disc specimens (h = 4 mm, r = 6 mm) (n = 9) and their shear bond strength (SBS) was measured. The surface morphology of disc specimens was analyzed with a scanning electron microscope (SEM). The Vickers microhardness (Vh), surface roughness (Ra), and three-point flexural strength (FS) of bar specimens (n = 9) were measured. Results were statistically analyzed with Mann-Whitney U-test (α = 0.05). RESULTS: Significant differences were found in FS and Vh values of the M and AM groups. M group (1501.4 ± 60.1 HV1) showed a significantly higher Vh value than the AM group (1169.2 ± 48.4 HV1) (p < 0.001). FS of the M group (1287.5 ± 115.2 MPa) exhibited significantly high value than the AM (1030.0 ± 29.2 Mpa) group (p < 0.001). Statistically, no significant differences were seen in SBS and Ra values of the M and AM groups. CONCLUSION: Within the limitations of this in vitro study, the manufacturing technique affected the mechanical properties of the zirconia materials. AM zirconia material showed lower Vh and FS values than M zirconia. Additionally AM zirconia demonstrated adequate bond strength with dental ceramic.

In vitro accuracies of 3D printed models manufactured by two different printing technologies.

PURPOSE: This study aims to compare the accuracies of full-arch models printed by two different 3D printing technologies. MATERIALS AND METHODS: A mandibular horseshoe-shaped master model was designed with RapidForm XOR2 software The master model was printed 10 times with 3D printers using direct light processing (DLP) and PolyJet technology (n=20). The printed models were then scanned with an industrial scanner and saved in STL file. All digital models superimposed with the master model STL file and comparison of the trueness was performed using Geomagic Control 3D analysis software. The precision was calculated by superimposing combinations of the 10 data sets in each group. RESULTS: The trueness of printed models was 46 µm for the DLP printer and 51 µm for PolyJet printer; however, this difference was not statistically significant (p=0.155). The precision of printed models was 43 µm for the DLP printer and 54 µm for PolyJet printer. DLP printed models were more precise than the PolyJet printed models (p<0.001). CONCLUSION: The 3D printing technologies showed significant differences in the trueness of full-arch measurements. Although DLP printed models had better trueness than PolyJet printed models, all of the 3D printed models were clinically acceptable and might be used for the production of fixed restorations.

Orthopedics and 3D technology in Turkey: A preliminary report.

OBJECTIVES: In this study, we present the use of case specific three-dimensional (3D) printed plastic models and custom-made acetabular implants in orthopedic surgery. MATERIALS AND METHODS: Between March 2018 and September 2020, surgeries were simulated using plastic models manufactured by 3D printers on the two patients with pilon fractures. Also, custom-made acetabular implants were used on two patients with an acetabular bone defect for the revision of total hip arthroplasty (THA). RESULTS: More comfortable surgeries were experienced in pilon fractures using preoperative plastic models. Similarly, during the follow-up period, the patients that applied custom-made acetabular implants showed a fixed and well-positioning in radiographic examination. These patients did not experience any surgical complications and achieved an excellent recovery. CONCLUSION: Preoperative surgical simulation with 3D printed models can increase the comfort of fracture surgeries. Also, custom-made 3D printed acetabular implants can perform an important task in patients treated with revision THA surgery due to severe acetabular defects.

Accuracy evaluation of complete-arch models manufactured by three different 3D printing technologies: a three-dimensional analysis.

Purpose This study aimed to evaluate the trueness and precision of complete-arch models printed with three-dimensional printers via three different printing technologies.Methods An arch-shaped master model was designed using software (RapidForm XOR2, 3D Systems Inc., USA), and the digital master model was printed 10 times with three-dimensional printers using stereolithography (SLA), direct light processing (DLP), and Polyjet technology (n = 30). The printed models were then scanned with an industrial scanner to create the respective digital models. All digital models were compared with the master model, and an evaluation of the trueness was performed by model superimposition with Geomagic Control software (3D Systems, Rock Hill, SC, USA). Precision was determined for each case by superimposing some combination of the 10 datasets in each group.Results The trueness of the printed models was 46.2 µm for the DLP printer, 51.6 µm for the SLA printer, and 58.6 µm for the Polyjet printer. The DLP models were significantly better than the Polyjet models (p = .005). However, the Polyjet models (30.4 µm) were more precise than the SLA (37.6 µm) and DLP (43.6 µm) models (p < .001, p = .016). Furthermore, the SLA (11.8 µm) was the most accurate printer in the Z-direction (p = .016, p = .002).Conclusions The 3D printing technologies showed significant differences in the precision and trueness of complete-arch measurements. Although DLP was more accurate other tested 3D printers, the accuracy of all 3D printed models was within clinical tolerance, and they were clinically acceptable and could be used for the production of fixed restorations.

Effects of magnetic resonance imaging on the microleakage of five restorative materials: An in vitro study.

OBJECTIVE: The objective of this study was to assess the effects of 3 T magnetic resonance imaging (MRI) on the microleakage of 5 restorative materials. METHODS: In total, 100 maxillary molars were randomly assigned to 5 groups (n = 20) for restoration with 5 different materials: amalgam, light-cured glass-ionomer cement, feldspathic porcelain fused to metal, pressed lithium disilicate glass ceramic, and composite resin. In each group, 10 specimens were subjected to MRI, and 10 specimens served as controls with no MRI exposure. Standardized class V cavities were prepared with occlusal margins terminating in enamel and gingival margins terminating in dentin. Microleakage penetration at the enamel and dentin margins was calculated for each group. A chi-square test was used for intergroup comparisons. Statistical significance was established at P < .05. RESULTS: Microleakage penetration did not differ significantly between specimens subjected to MRI and the controls for any restoration (P ≥ .362 for the enamel margin, P ≥ .067 for the dentin margin) or between specimens treated with different restorative materials (P ≥ .355). No significant differences in microleakage were discovered between the enamel and dentin margins of any of the restorative groups (P ≥ .236). CONCLUSION: MRI had no effect on the microleakage of the 5 restorative materials.

Effect of 1.5-T and 3.0-T magnetic resonance imaging on the ceramic adhesion and physical properties of prosthetic substructures.

STATEMENT OF PROBLEM: Magnetic resonance imaging (MRI) is a cross-sectional imaging technique that is widely used in the detection of pathologies in the head and neck region. However, information is lacking about the effect of MRI imaging on the clinical success of fixed partial dentures (FPDs). PURPOSE: The purpose of this in vitro study was to analyze the effect of MRI on the physical properties and ceramic adhesion of FPD substructure materials. MATERIAL AND METHODS: Three hundred disk (12×1 mm) and 255 rectangular (4×2×2 mm) specimens were prepared with different fabrication techniques for 5 experimental groups: direct metal laser sintering (DMLS) with Co-Cr and Ti; casting with Co-Cr and Ni-Cr; and milling with ZrO2. After ceramic application, the disk specimens were subjected to aging and divided into 3 subgroups (n=20) with exposure to 1.5-T and 3.0-T MRI brain scans for 30 minutes and no exposure (control). The shear bond strength (SBS) of the specimens was measured by using a universal testing machine. The rectangular specimens were exposed to MRI with the same procedure, and the nanostructure of the specimens was analyzed with the small-angle X-ray scattering (SAXS) method to detect the nanoscale structural effects of MRI. The average surface roughness (Ra) and Vickers microhardness (Vh) were also measured for complementary analyses. SBS, Ra, and Vh values were statistically analyzed by 1-way ANOVA and the Tukey honestly significant difference test (α=.05). RESULTS: The SBS (MPa) of casting groups (P<.001) and DMLS with the Co-Cr group (P<.05) were significantly affected by MRI exposures. The significant differences were seen on the Ra of casting (P<.001) and DMLS with Co-Cr (P<.05) and Ti (P<.01) groups. Also, the Vh of the casting with Co-Cr (P<.001) and Ni-Cr (P<.01) groups showed significant differences. The SAXS analysis indicated that the physical properties of materials were influenced by MRI exposure. CONCLUSIONS: The results indicated that MRI applications affected the metal-ceramic adhesion of Co-Cr and Ni-Cr dental alloys produced by casting and the DMLS technique.

Effect of Denture Cleansing Solutions on the Retention of Locator Attachments Over Time.

PURPOSE: To evaluate and compare the alterations in retention of three Locator attachments after immersion in various denture cleansers at defined time intervals. MATERIALS AND METHODS: Two implants were embedded in an acrylic block. Pink, blue, and clear Locator attachments (n = 10 for each subgroup) were immersed into three different cleansing solutions (Corega, Protefix and NaOCl) and tap water (control) at different time intervals that simulate 1 (T1 ), 6 (T2 ), and 12 (T3 ) months of clinical use. Universal testing machine set at a crosshead speed of 50 mm/min was used for pull-out tests. After the immersion procedure, the peak force to dislodgement was recorded to demonstrate the changes in retention of Locator attachments. Data were analyzed using repeated-measures ANOVA followed by Tukey's Honestly Significant Difference (HSD) tests (α = .05). RESULTS: All denture cleansing solutions affected the retentive values of all Locator attachments at defined time intervals (F = 4.299, p = 0.001). NaOCl affected all groups significantly after 12-month immersion time (p = 0.001). The least retention loss at all subgroups was observed in Corega for clear Locator attachments (106.17 ± 5.21 N). The difference in retention values for pink attachments were not statistically significant for tap water, Protefix and Corega immersion at all time intervals (p > 0.05). Following NaOCl (blue; 33.31 ± 4.72 N, clear; 52.3 ± 8.5 N), tap water decreased the retention value of blue (41.14 ± 3.93 N) and clear (76.72 ± 8.42 N) Locator attachments at T3 . Corega caused the least retention loss to clear attachments at T1 (106.17 ± 3.55 N). CONCLUSION: The retention of Locator attachments decreases over time after exposure to various denture cleansing solutions. As NaOCl significantly decreased the retentive values of all attachments, patients must be informed about that disadvantage. Also, tap water remarkably decreased retentive ability of all attachments. Periodic addition of an effervescent tablet into tap water may be recommended to patients that wear implant retained overdentures with Locator attachments.

3D-Printed Splitter for Use of a Single Ventilator on Multiple Patients During COVID-19.

During epidemics or pandemics affecting the respiratory systems, hospital equipment such as ventilators may become insufficient and different solutions can be considered. In fast spreading respiratory illnesses such as COVID-19 due to the rapidly increasing number of patients, ventilatory machine insufficiencies may appear. It may be considered to use one hospital ventilator for more than one patient by dividing the airway of the machine with a specially designed splitter. The aim of this study was to determine whether a ventilator can be modified to provide ventilation of two or more patients simultaneously by using 3D designed and manufactured splitters. A two-port and four-port splitter were designed in Autodesk Fusion 360 computer program and manufactured by 3D printer using PolyJet technology (Stratasys J750). Two sets of splitters were used to adapt to the ventilator during trial process: one for inspiratory and one for expiratory outputs. Two intensive care specialists voluntarily tried this study on themselves. It was concluded from the study that 3D designed and manufactured two-port splitter can be used to separate the airway of a single ventilator to multiple patients within a very limited indication and time interval.

Evaluation of the trueness and precision of eight extraoral laboratory scanners with a complete-arch model: a three-dimensional analysis.

PURPOSE: The purpose of this study was to evaluate the trueness and precision of eight different extraoral laboratory scanners using three-dimensional (3D) analysis method. METHOD: An arch-shaped master model was designed with a computer software (Rapidform XOR2) and manufactured with a 3D printer (Projet 3510 MP). Then the master model was digitized with an industrial 3D scanner (ATOS Core 200). With each scanner master model was scanned ten times and stereolithography (.stl) data were imported into 3D analysis software (Geomagic Control). Accuracy was determined with evaluating trueness and precision. RESULTS: Trueness of the scanners were 27.5 µm for 7 series; 30.9 µm for D640; 26.8 µm for D710; 33.3 µm for Activity 102; 32.4 µm for Tizian Smart-Scan; 21.6 µm for NeWay; 26.1 µm for inEOS X5 and 17,47 µm for D2000. 28.2 µm for laser; 32.9 µm for white light and 21.7 µm for blue light scanners. Significant differences were found between scanners (p < .001), (p < .001). Precision of the scanners were 30.1 µm for 7 series; 31.7 µm for D640; 26.3 µm for D710; 22.7 µm for Activity 102; 25.1 µm for Tizian Smart-Scan; 15.7 µm for NeWay; 26.1 µm for inEOS X5; 16.6 µm for D2000. 29.2 µm for laser; 24.4 µm for white light and 19.2 µm for blue light scanners. Significant differences were found between scanners (p < .001), (p = .027). CONCLUSIONS: The systems that had the best combination of trueness and precision for complete-arch scanning were D2000 and NeWay. Scanners using blue-light showed more accurate results than the white-light and laser scanners.

What is the changing frequency of diamond burs?

PURPOSE: The purpose of this study was to determine the changing frequency of a diamond bur after multiple usages on 3 different surfaces. MATERIALS AND METHODS: Human premolar teeth (N = 26), disc shaped direct metal laser sintered CoCr (N = 3) and zirconia specimens (N = 3) were used in this study. Groups named basically as Group T for teeth, Group M for CoCr, and Group Z for zirconia. Round tapered black-band diamond bur was used. The specimens were randomly divided into three groups and placed with a special assembly onto the surveyor. 1, 5, and 10 preparation protocols were performed to the first, second, and third sub-groups, respectively. The subgroups were named according to preparation numbers (1, 5, 10). The mentioned bur of each group was then used at another horizontal preparation on a new tooth sample. The same procedure was used for CoCr and zirconia disc specimens. All of the bur surfaces were evaluated using roughness analysis. Then, horizontal tooth preparation surfaces were examined under both stereomicroscope and SEM. The depth maps of tooth surfaces were also obtained from digital stereomicroscopic images. The results were statistically analyzed using One-Way ANOVA, and the Tukey HSD post-hoc tests (α=.05). RESULTS: All of the groups were significantly different from the control group (P<.001). There was no significant difference between groups Z5 and Z10 (P=.928). Significant differences were found among groups T5, M5, and Z5 (P<.001). CONCLUSION: Diamond burs wear after multiple use and they should be changed after 5 teeth preparations at most. A diamond bur should not be used for teeth preparation after try-in procedures of metal or zirconia substructures.

Influence of core thickness and artificial aging on the biaxial flexural strength of different all-ceramic materials: An in-vitro study.

The purpose of this study was to investigate the flexural strength of all-ceramics with varying core thicknesses submitted to aging. In-Ceram Alumina (IC), IPS e.max Press (EM) and Katana (K) (n=40), were selected. Each group contained two core groups based on the core thickness as follows: IC/0.5, IC/0.8, EM/0.5, EM/0.8, K/0.5 and K/0.8 mm in thickness (n=20 each). Ten specimens from each group were subjected to aging and all specimens were tested for strength in a testing machine either with or without being subjected aging. The mean strength of the K were higher (873.05 MPa) than that of the IC (548.28 MPa) and EM (374.32 MPa) regardless of core thickness. Strength values increased with increasing core thickness for all IC, EM and K regardless of aging. Results of this study concluded that strength was not significantly affected by aging. Different core thicknesses affected strength of the all-ceramic materials tested (p<0.05).

Evaluation of Low-Level Laser Therapy in TMD Patients.

Light amplification by stimulated emission of radiation (laser) is one of the most recent treatment modalities in dentistry. Low-level laser therapy (LLLT) is suggested to have biostimulating and analgesic effects through direct irradiation without causing thermal response. There are few studies that have investigated the efficacy of laser therapy in temporomandibular disorders (TMD), especially in reduced mouth opening. The case report here evaluates performance of LLLT with a diode laser for temporomandibular clicking and postoperative findings were evaluated in two cases of TMD patients. First patient had a history of limited mouth opening and pain in temporomandibular joint (TMJ) region since nine months. Second patient's main complaint was his restricted mouth opening, which was progressed in one year. LLLT was performed with a 685 nm red probed diode laser that has an energy density of 6.2 J/cm(2), three times a week for one month, and application time was 30 seconds (685 nm, 25 mW, 30 s, 0.02 Hz, and 6.2 J/cm(2)) (BTL-2000, Portative Laser Therapy Device). The treatment protocol was decided according to the literature. One year later patients were evaluated and there were no changes. This application suggested that LLLT is an appropriate treatment for TMD related pain and limited mouth opening and should be considered as an alternative to other methods.

Progressive Hemifacial Atrophy With Contralateral Uveitis: A Case Report.

INTRODUCTION: Progressive hemifacial atrophy, known as Parry-Romberg syndrome (PRS), was first described by Parry in 1825. There is a progressive atrophy of facial tissues including skin, bones and muscles. Ophthalmic disorders are common and include keratitis, uveitis, cataract, ipsilateral enophthalmos, optic neuritis, retinal vasculitis and scleral melting. CASE PRESENTATION: We describe a patient with progressive hemifacial atrophy at right facial side who developed granulomatous uveitis and periferic retinal vasculitis in his left eye. We started topical and systemic steroid therapy. Uveitic reaction had regressed almost entirely after a 3-month steroid treatment. CONCLUSIONS: The individuals should have multidisciplinary approach for the variety of disorders to maintain the appropriate treatment for a better appearance of the patients.