A Comparative Study on Fungal Diversity in Organic and Conventionally Cultivated Lemons During Accelerated Storage.

There has been a growing interest in organic farming as a countermeasure to the environmental burden caused by chemical pesticides. We analyzed and compared the fungal diversity of lemon fruits from organic and conventional cultivation by automated rRNA intergenic spacer analysis (ARISA), accompanied by isolation of cultured colonies and metagenomic analysis. Lemon peels were cut out and subjected to the analyses at purchase and after accelerated storage at 28 °C. The organic lemons did not decay even after 14 weeks, while most of the conventional lemons did decay. The fungal colony counts were not significantly different, although the number of fungal species together with the Shannon index, considering the abundance of each species, clearly showed more diversity in organic lemons than in conventional lemons (p = 0.011). Fusarium sp. (putative F. solani) accounted for as much as 90% of the relative abundance in the decayed conventional lemons. Metagenomic analysis also supported the lack of fungal diversity in conventional lemons. These results may suggest that organic cultivation maintains the diversity of native fungal flora in lemon fruit and could contribute to preventing decay during ambient storage.

Impaired dental implant osseointegration in rat with streptozotocin-induced diabetes.

OBJECTIVE: Few studies have reported on the impact of oxidative stress on the dental implant failure. The aim of this study was to investigate the impact of hyperglycemia-induced oxidative stress on dental implant osseointegration in diabetes mellitus (DM). METHODS: Acid-treated titanium implants were bilaterally placed in the maxillary alveolar ridge of streptozotocin-induced diabetic (DM group) and control rats after extraction of first molars. Histological analysis and micro-push-out test were performed 4 weeks after surgery. Oxidative stress and osteogenic markers in the surrounding bone were quantified by real-time polymerase chain reaction. In the in vitro study, rat bone marrow-derived mesenchymal stem cells (BMMSCs) were cultured on acid-treated titanium discs in a high-glucose (HG) or normal environment. Intracellular reactive oxygen species (ROS), cell proliferation, alkaline phosphatase (ALP) activity, and extracellular calcification were evaluated following antioxidant treatment with N-acetyl-L-cysteine (NAC). RESULTS: The implant survival rate was 92.9% and 75.0% in control and DM group, respectively. Bone-implant contact and push-out loads were significantly lower in the DM group. Expression of superoxide dismutase 1 at the mRNA level and on immunohistochemistry was significantly lower in the DM group. In vitro experiments revealed that the HG condition significantly increased ROS expression and suppressed the proliferation and extracellular calcification of BMMSCs, while NAC treatment significantly restored ROS expression, cell proliferation, and calcification. The ALP activity of both groups was not significantly different. CONCLUSION: In diabetes, high-glucose-induced oxidative stress downregulates proliferation and calcification of BMMSCs, impairing osseointegration and leading to implant failure.

Tumor contact length of prostate cancer determined by a three-dimensional method on multiparametric magnetic resonance imaging predicts extraprostatic extension and biochemical recurrence.

OBJECTIVE: To evaluate the clinical benefit of tumor contact length as a predictor of pathological extraprostatic extension and biochemical recurrence in patients undergoing prostatectomy. METHODS: A total of 91 patients who underwent 3T multiparametric magnetic resonance imaging before prostatectomy from April 2014 to July 2019 were included. A total of 94 prostate cancer foci were analyzed retrospectively. We evaluated maximum tumor contact length, which was determined to be the maximum value in the three-dimensional directions, as a predictor of pathological extraprostatic extension and biochemical recurrence. RESULTS: A total of 19 lesions (20.2%) had positive pathological extraprostatic extension. Areas under the curves showed maximum tumor contact length to be a significantly better parameter to predict pathological extraprostatic extension than the Prostate Imaging Reporting and Data System (P = 0.002), tumor maximal diameter (P = 0.001), prostate-specific antigen (P = 0.020), Gleason score (P < 0.001), and clinical T stage (P < 0.001). Multivariate analysis showed maximum tumor contact length (P = 0.003) to be an independent risk factor for predicting biochemical recurrence. We classified the patients using preoperative factors (prostate-specific antigen >10, Gleason score >3 + 4 and maximum tumor contact length >10 mm) into three groups: (i) high-risk group (patients having all factors); (ii) intermediate-risk group (patients having two of three factors); and (iii) low-risk group (patients having only one or none of the factors). Kaplan-Meier curves showed that the high-risk group had significantly worse biochemical recurrence than the intermediate-risk group (P = 0.042) and low-risk group (P < 0.001). CONCLUSIONS: Our findings suggest that maximum tumor contact length is an independent predictor of pathological extraprostatic extension and biochemical recurrence. A risk stratification system using prostate-specific antigen, Gleason score and maximum tumor contact length might be useful for preoperative assessment of prostate cancer patients.

Ultraviolet Treatment of Titanium to Enhance Adhesion and Retention of Oral Mucosa Connective Tissue and Fibroblasts.

Peri-implantitis is an unsolved but critical problem with dental implants. It is postulated that creating a seal of gingival soft tissue around the implant neck is key to preventing peri-implantitis. The objective of this study was to determine the effect of UV surface treatment of titanium disks on the adhesion strength and retention time of oral connective tissues as well as on the adherence of mucosal fibroblasts. Titanium disks with a smooth machined surface were prepared and treated with UV light for 15 min. Keratinized mucosal tissue sections (3 × 3 mm) from rat palates were incubated for 24 h on the titanium disks. The adhered tissue sections were then mechanically detached by agitating the culture dishes. The tissue sections remained adherent for significantly longer (15.5 h) on the UV-treated disks than on the untreated control disks (7.5 h). A total of 94% of the tissue sections were adherent for 5 h or longer on the UV-treated disks, whereas only 50% of the sections remained on the control disks for 5 h. The adhesion strength of the tissue sections to the titanium disks, as measured by tensile testing, was six times greater after UV treatment. In the culture studies, mucosal fibroblasts extracted from rat palates were attached to titanium disks by incubating for 24, 48, or 96 h. The number of attached cells was consistently 15-30% greater on the UV-treated disks than on the control disks. The cells were then subjected to mechanical or chemical (trypsinization) detachment. After mechanical detachment, the residual cell rates on the UV-treated surfaces after 24 and 48 h of incubation were 35% and 25% higher, respectively, than those on the control surfaces. The remaining rate after chemical detachment was 74% on the control surface and 88% on the UV-treated surface for the cells cultured for 48 h. These trends were also confirmed in mouse embryonic fibroblasts, with an intense expression of vinculin, a focal adhesion protein, on the UV-treated disks even after detachment. The UV-treated titanium was superhydrophilic, whereas the control titanium was hydrophobic. X-ray photoelectron spectroscopy (XPS) chemical analysis revealed that the amount of carbon at the surface was significantly reduced after UV treatment, while the amount of TiOH molecules was increased. These ex vivo and in vitro results indicate that the UV treatment of titanium increases the adhesion and retention of oral mucosa connective tissue as a result of increased resistance of constituent fibroblasts against exogenous detachment, both mechanically and chemically, as well as UV-induced physicochemical changes of the titanium surface.

Magnetic resonance imaging/transrectal ultrasonography fusion targeted prostate biopsy finds more significant prostate cancer in biopsy-naïve Japanese men compared with the standard biopsy.

OBJECTIVE: To assess the clinical benefits of magnetic resonance imaging/transrectal ultrasound fusion-targeted biopsy for biopsy-naïve Japanese men. METHODS: Between February 2017 and August 2018, 131 biopsy-naïve men who underwent targeted biopsy together with 10-core systematic biopsy at Hiroshima University Hospital were retrospectively investigated. Multiparametric magnetic resonance imaging findings were reported based on Prostate Imaging Reporting and Data System version 2. RESULTS: The overall cancer detection rates per patient were 69.5% in systematic biopsy + targeted biopsy cores, 61.1% in systematic biopsy cores and 61.1% in targeted biopsy cores. The detection rates for clinically significant prostate cancer were 43.5% in targeted biopsy cores and 35.9% in systematic biopsy cores (P = 0.04), whereas the detection rates for clinically insignificant prostate cancer were 17.6% and 25.2% respectively (P = 0.04). Lesions in the peripheral zone were diagnosed more with clinically significant prostate cancer (54.8% vs 20.7%, P < 0.001) and International Society of Urological Pathology grade (3.2 vs 2.7, P = 0.02) than that in the inner gland. Just 4.2% (3/71) of Prostate Imaging Reporting and Data System category 2 and 3 lesions in the middle or base of the inner gland were found to have clinically significant prostate cancer. The cancer detection rate per core was 42.3% in targeted biopsy cores, whereas it was 17.9% in systematic biopsy cores (P < 0.001). CONCLUSIONS: Targeted biopsy is able to improve the diagnostic accuracy of biopsy in detection of clinically significant prostate cancer by reducing the number of clinically insignificant prostate cancer detections compared with 10-core systematic biopsy in biopsy-naïve Japanese men. In addition, the present findings suggest that patients with Prostate Imaging Reporting and Data System category 2 or 3 lesions at the middle or base of the inner gland might avoid biopsies.

Stiripentol alleviates neuropathic pain in L5 spinal nerve-transected mice.

PURPOSE: Antiepileptic drugs are used not only for the treatment of epilepsy but also for that of neuropathic pain. However, their action mechanisms have not always been well explained. Stiripentol, an effective antiepileptic drug indicated as a therapeutic for Dravet syndrome, was recently shown to act as an inhibitor of lactate dehydrogenase in astrocytes. In this present study, we examined the effect of stiripentol on neuropathic pain in L5 spinal nerve-transected mice. METHODS: We carried out behavioral tests using calibrated von Frey filaments and the immunohistochemistry of glial fibrillary acidic protein, an astrocyte marker, in L5 spinal nerve-transected mice after intrathecal administration of drugs. RESULTS: Like other anticonvulsants such as gabapentin and carbamazepine, stiripentol alleviated mechanical hyperalgesia induced by L5 spinal nerve transection in a dose-dependent manner, when intrathecally administered to mice 7, 14, and 28 days after L5 spinal nerve transection. Likewise, α-cyano-4-hydroxycinnamic acid, a broad inhibitor of monocarboxylate transporters, diminished mechanical hyperalgesia induced by L5 spinal nerve transection. Simultaneous administration of L-lactate negated the analgesic effect elicited by stiripentol, carbamazepine or α-cyano-4-hydroxycinnamic acid, but not that by gabapentin. None of the anticonvulsants affected the immunoreactivity of glial fibrillary acidic protein. CONCLUSIONS: This present study demonstrated that stiripentol was effective against neuropathic pain and suggested that the astrocyte-neuron lactate shuttle was involved in such pain.

Correction to: Stiripentol alleviates neuropathic pain in L5 spinal nerve-transected mice.

In the original publication of the article, the value "40-µm thickness" was incorrect in the legend of Figure 4. The correct value is 10-µm thickness.

[Outcomes of Laparoscopic Radical Prostatectomies by a Single Surgeon Alternating Operating Position].

The clinical outcome of laparoscopic radical prostatectomy (LRP) was retrospectively investigated taking into consideration the surgeon's position during the procedure. The study cohort included 184 consecutive patients who had undergone LRP performed by a single surgeon from February 2013 to July 2018. During the study period,the surgeon stood alternately on either the left or right side of the patient. The D'Amico risk classification was low,intermediate and high in 26 (14.1%),45 (24.5%) and 113 (61.4%) patients,respectively. Mean surgical duration was 203.5 minutes and mean estimated blood loss was 437.6 ml. Nerve sparing (NS) was implemented in 82 (44. 6%) patients. The mean period of having an indwelling urethral catheter was 5. 0 days. Perioperative Clavien-Dindo degree ≥IIIa complications occurred in three (1.6%) patients. Except for cases with presurgical hormonal treatment,surgical margins were positive in 41 (22.3%) patients,among whom 23 (17.4%) had pT2 disease. The 5-year biochemical recurrence-free survival rate was 81.4%,and 84.8% of patients regained urinary continence at 12 months after surgery. Where the surgeon stood during LRP was not associated with significant differences in any parameter. However,the margin positive rate was higher on the side away from where the surgeon stood than the side closer to the surgeon (70.7% vs 29.3%). In conclusion,the position of the surgeon during LRP does not influence the outcome.

Cytoprotective Preconditioning of Osteoblast-Like Cells with N-Acetyl-L-Cysteine for Bone Regeneration in Cell Therapy.

Oxidative stress hinders tissue regeneration in cell therapy by inducing apoptosis and dysfunction in transplanted cells. N-acetyl-L-cysteine (NAC) reinforces cellular antioxidant capabilities by increasing a major cellular endogenous antioxidant molecule, glutathione, and promotes osteogenic differentiation. This study investigates the effects of pretreatment of osteoblast-like cells with NAC on oxidative stress-induced apoptosis and dysfunction and bone regeneration in local transplants. Rat femur bone marrow-derived osteoblast-like cells preincubated for 3 h with and without 5 mM NAC were cultured in a NAC-free osteogenic differentiation medium with continuous exposure to 50 µM hydrogen peroxide to induce oxidative stress. NAC preincubation prevented disruption of intracellular redox balance and alleviated apoptosis and negative impact on osteogenic differentiation, even under oxidative stress. Autologous osteoblast-like cells with and without NAC pretreatment in a collagen sponge vehicle were implanted in critical-size defects in rat femurs. In the third week, NAC-pretreated cells yielded complete defect closure with significantly matured lamellar bone tissue in contrast with poor bone healing by cells without pretreatment. Cell-tracking analysis demonstrated direct bone deposition by transplanted cells pretreated with NAC. Pretreatment of osteoblast-like cells with NAC enhances bone regeneration in local transplantation by preventing oxidative stress-induced apoptosis and dysfunction at the transplanted site.

Tracheal Tube Position Shift During Infant Resuscitation by Chest Compression: A Simulation Comparison by Fixation Method and With or Without Cuff.

BACKGROUND: Tracheal tube placement during infant resuscitation is essential for definite airway protection. Accidental extubation due to tracheal tube displacement is a rare event, but it results in severe complications, especially in infants. OBJECTIVE: The present study evaluated how infant tracheal tube displacement is affected by tape vs. tube holder fixation using a manikin. METHODS: A tracheal tube with internal diameter of 3.5 mm was placed 10 cm from the gum ridge in an advanced life support (ALS) Baby(®) simulator (Laerdal, Stavanger, Norway). In the first trial, cuff pressure was set at 15, 20, and 25 cmH2O and trials were performed at each setting with no fixation, Durapore(®) (3M, St Paul, MN) tape fixation, Multipore(®) (3M) tape fixation, and Thomas(®) Tube Holder (Laerdal) fixation. After 5 min of chest compression, the tracheal tube shift was measured. In the second trial, we compared the tube shift by chest compression with or without cuff in the same way. RESULTS: Relative to no fixation, tracheal tube shift was significantly less in the Durapore, Multipore, and tube holder groups (p < 0.05) at all cuff settings. Of the three fixation methods, the tube holder showed significantly less shift (p < 0.05) relative to tape, regardless of the initial cuff pressure. The positional shift after chest compressions was significantly larger in the trials with cuff than in those without cuff in Durapore or Multipore fixation (p < 0.05), but did not in tube holder fixation. CONCLUSIONS: There is less tracheal tube displacement with tube holder fixation than with tape during continuous infant chest compression simulation. The tube cuff can contribute to the positional shift of the tube during infant chest compression.

[Nasal Endotracheal Intubation Using a Gum-elastic Bougie and the Nasopharyngeal Airway in a Patient under Cervical Stabilization].

Here we report a case of successful nasal endotra- cheal intubation using a gum-elastic bougie and the nasopharyngeal airway (NPA) in a patient under cervical stabilization. A 40-year-old woman was sched- uled to undergo spinal fusion surgery from the anterior approach for symptomatic cervical spondylotic myelop- athy under general anesthesia with nasal intubation. As she had paralysis and presented with numbness in her limbs, the airway was planned to be secured under cervical stabilization. After induction of anesthesia with propofol, fentanyl, and rocuronium, mask ventilation was achieved with the jaw-thrust maneuver. A gum- elastic bougie (GEB) was inserted into her nasal cavity and passed into the trachea under gentle laryngoscopy. We attempted insertion of the spiral tracheal tube (internal diameter, 7.0 mm) along the GEB, which was impossible. We then inserted NPA (internal diameter, 8.0 mm) via the GEB and dilated the cavity. After NPA removal, the spiral tube successfully progressed railing on the GEB. The operation was uneventful, and the patient was extubated in the operating room.

[Anesthetic Management of a Pediatric Case of Blue Rubber Bleb Nevi Syndrome Combined with Small-intestinal Intussusception].

We report the anesthetic management of a pediatric case of blue rubber bleb nevi syndrome combined with small-intestinal intussusception. A 2-year-old girl was transferred to our hospital for small-intestinal intussusception. Emergent ablation of the upper gastrointestinal tract nevus under general anesthesia was planned. Given the presence of several nevi in the oral and pharyngeal space, we utilized the McGRATH MAC (McGRATH; Aircraft Medical Ltd, United Kingdom) laryngoscope for gentle and stress-free tracheal intubation. The venous line was kept patent preoperatively, and rapid-sequence intubation was performed with the McGRATH (size 2 pediatric blade). A 4.5-mm tracheal tube was inserted uneventfully under direct visualization. The trachea was observed and the tube maintained in a proper position with a bronchofiberscope. During the procedure, cuff volume was regulated to avoid excessive increase by upper gastrointestinal endoscope insertion. The girl was extubated in the operating room and showed no postoperative complications such as hemorrhage or hoarseness.

Urinary tract fungal ball in a single kidney after total nephroureterocystectomy.

Introduction: Fungal balls in the urinary tract are rare but dangerous complications of candiduria. Here, we report a case of a urinary tract fungal ball in a single kidney after total nephroureterocystectomy. Case presentation: The patient was an 80-year-old male. He had a history of pyelonephritis, and his ureteral stent was regularly replaced. He was admitted to the hospital with a chief complaint of urinary tract obstruction, and a 50-mm-sized mass was found within the renal pelvis. Because the ureteral stent frequently became obstructed, the mass was removed percutaneously. Candida albicans was detected on the tissue culture results, and the mass was diagnosed as a fungal ball. Conclusion: Appropriate urinary drainage methods for fungal balls vary among patients, and it is important to select an appropriate method based on the accumulated number of cases.

Origins, genetic structure, and systematics of the narrow endemic peatmosses (Sphagnum): S. guwassanense and S. triseriporum (Sphagnaceae).

PREMISE OF THE STUDY: Sphagnum dominates vast expanses of wetland habitats throughout the northern hemisphere and species delimitation within the genus is important because floristic changes associated with a warming global climate may have measureable impacts on large-scale ecological processes. Most northern hemisphere peatmoss species (Sphagnum) have circumboreal ranges, but the Japanese species generally known as S. calymmatophyllum is endemic to Honshu Island. This prompted a population genetic and phylogenetic analysis to resolve the origin(s), population structure, and phylogenetic relationships of this morphologically variable species. • METHODS: Sixty plants collected from Mt. Gassan and Mt. Hakkoda were genotyped for 12 microsatellite loci. Two plastid loci and three anonymous nuclear loci were sequenced in a subset of the plants, plus representatives from 10 closely related species. • KEY RESULTS: Gametophytes exhibited fixed or nearly fixed heterozygosity at 9-10 of the 12 microsatellite loci. Two genetic groups were resolved by the microsatellite data, individuals showed no evidence of admixture, and the two groups of plants differ in morphology. They are heterozygous for different sets of alleles. The two taxa share plastid DNA sequences with two species that are common in Alaska. • CONCLUSIONS: Two taxa were distinguished: S. guwassanense and S. triseriporum. Both are allopolyploids; they originated independently from different but closely related progenitors. The maternal progenitor was likely either S. orientale or S. inexspectatum. The two allopolyploid taxa are heterozygous for (different) private microsatellite alleles, and one progenitor could be extinct.

Early-stage osseointegration capability of a submicrofeatured titanium surface created by microroughening and anodic oxidation.

OBJECTIVE: The role of nanoscale/submicron morphological features in the process of osseointegration is largely unknown. This study reports the creation of a unique submicrofeatured titanium surface by a combination of anodic oxidation and sandblasting and determines how the addition of this submicrofeature to a microroughened surface affects the early-stage process of osseointegration. MATERIALS AND METHODS: Nonmicroroughened implants were prepared by machining Ti-6Al-4V alloy in a cylindrical form (1 mm diameter and 2 mm long). Microroughened implants were prepared by sandblasting machined implants, while submicrofeatured implants were created by anodic oxidation of the sandblasted implants. Implants were placed into rat femurs and subjected to biomechanical, interfacial, and histological analyses at 1 and 2 weeks post-implantation (n = 6). RESULTS: The submicrotopography was characterized by 50-300 nm nodules and pits in addition to other submicron-level irregularities formed entirely within the sandblast-created microstructures. The biomechanical strength of osseointegration increased continuously from week 1 to 2 for the submicrofeatured implants but not for the microroughened implants. A significant increase in bone-implant contact and bone volume, as well as a reduction in soft tissue intervention, were commonly found for the microroughened surface and the submicrofeatured surface compared with the nonmicroroughened surface. However, there were no differences in these parameters between the microroughened surface and the submicrofeatured surface. An extensive area of bone tissue at the submicrofeatured implant interface was retained intact after biomechanical shear testing, while the microroughened implant-tissue interface showed a gap along the entire axis of the implant, leading to clear separation of the tissue during the shear procedure. CONCLUSIONS: This study demonstrates that a submicrofeatured titanium surface created by a combination of sandblasting and anodic oxidation enhances the strength of early-stage osseointegration, primarily because of the increased resistance of peri-implant bone tissue against external force rather than modulation of bone morphogenesis.

A review in titanium-zirconium binary alloy for use in dental implants: Is there an ideal Ti-Zr composing ratio?

Binary titanium-zirconium alloys have been studied as promising alternatives for Ti implants. The commercial Ti-15Zr alloy (Roxolid, Straumann) has been the major subject of numerous binary Ti-Zr alloys-related studies and has gained wide recognition in laboratory studies and clinical practices. However, binary Ti-Zr alloys of other composition ratios are still being investigated by researchers. This review aims to provide information on the potential of binary Ti-Zr alloys other than Ti-15Zr as implant materials in terms of mechanical strengths, chemical or electrochemical corrosion resistance capabilities, and biological performances. In addition, in this review, the Ti-15Zr alloy is discussed only when compared with other binary Ti-Zr alloys. From the included 26 studies, it is confirmed that the mechanical, chemical, electrochemical, and biological properties of Ti-Zr alloys are related to the Ti and Zr composition ratio in the alloy, phase, manufacturing process, and surface treatment. Among the studied alloys, α-or α' phase-Ti-5 wt, 45 wt/30at, and 50 wt. %Zr exhibited relatively more promising results for further investigation. More research is necessary to evaluate the potential for future use of these materials for implants.

Lithium-Modified TiO2 Surface by Anodization for Enhanced Protein Adsorption and Cell Adhesion.

Promoting osseointegration is an essential step in improving implant success rates. Lithium has gradually gained popularity for promoting alkaline phosphatase activity and osteogenic gene expression in osteoblasts. The incorporation of lithium into a titanium surface has been reported to change its surface charge, thereby enhancing its biocompatibility. In this study, we applied anodization as a novel approach to immobilizing Li on a titanium surface and evaluated the changes in its surface characteristics. The objective of this study was to determine the effect of Li treatment of titanium on typical proteins, such as albumin, laminin, and fibronectin, in terms of their adsorption level as well as on the attachment of osteoblast cells. Titanium disks were acid-etched by 66 wt % H2SO4 at 120 °C for 90 s and set as the control group. The etched samples were placed in contact with an anode, while a platinum bar served as the counter electrode. Both electrodes were mounted on a custom electrochemical cell filled with 1 M LiCl. The samples were anodized at constant voltages of 1, 3, and 9 V. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) results showed no significant differences in the topography. However, the ζ potentials of the 3 V group were higher than those of the control group at a physiological pH of 7.4. Interestingly, the adsorption level of the extracellular matrix protein was mostly enhanced on the 3 V-anodized surface. The number of attached cells on the Li-anodized surfaces increased. The localization of vinculin at the tips of the stretching cytoplasmic projections was observed more frequently in the osteoblasts on the 3 V-anodized surface. Although the optimal concentration or voltage for Li application should be investigated further, this study suggests that anodization could be an effective method to immobilize lithium ions on a titanium surface and that modifying the surface charge characteristics enables a direct protein-to-material interaction with enhanced biological adhesion.

Knowledge acquisition efficacy of a remote flipped classroom on learning about removable partial dentures.

PURPOSE: Coronavirus disease 2019 has forced the use of remote education worldwide. In 2020, the authors conducted a fully digitized, remote flipped (RF) classroom focusing on removable partial dentures. This study aimed to evaluate the learning outcomes of the RF classroom and compare these with those of the on-site classroom. METHODS: The fourth-year dental students in 2017-2019 attended on-site flipped classroom (OF; n=70) or on-site lecture classroom (OL; n=67), and those in 2020 (n=58) attended the RF classroom. Lecture videos and text were provided online in the OF and RF groups, while only the text was given to the OL group. Individual and group tests were conducted to assess knowledge acquisition one week after all the classes ended. A one-way analysis of variance following Tukey's test was performed to compare individual/group test scores among the OF, OL, and RF groups. Multilevel linear regression analysis was performed to identify the factors associated with an increase in each test score. RESULTS: The mean individual test scores in the RF and OF groups were significantly higher than in the OL group (P<0.01). The mean group test score in the RF group was significantly higher than in the OF and OL groups (P<0.001). The multilevel analysis identified remote and flipped classroom styles in the individual test, and the remote style in the group test, as significant effective factors in learning (P<0.05). CONCLUSIONS: These results suggest that the RF classroom is more effective than the on-site lecture in knowledge acquisition in undergraduate prosthodontic education.

A systematic review of digital removable partial dentures. Part I: Clinical evidence, digital impression, and maxillomandibular relationship record.

PURPOSE: This study comprehensively reviewed the current status of digital workflows in fabricating removable partial dentures (RPDs) using evidence from clinical trials and case reports. STUDY SELECTION: We performed a systematic review of the literature on the materials and fabrication of RPDs using digital technologies published in online databases from 1980 to 2020. We selected eligible articles from the search results, retrieved information on digital RPDs from these, and conducted a qualitative analysis. We report evidence from clinical papers and case reports, digital impression-taking methods, and maxillomandibular relationship (MMR) records. RESULTS: A case report electronically published in 2019 introduced a clasp-retained RPD fabricated via a full-digital workflow without a gypsum definitive cast. Computer-aided design and computer-aided manufacturing of double-crown-retained RPDs with nonmetal materials were described in some case reports. Intraoral scanners were used to obtain digital impressions and MMR records in the fabrication of digital RPDs, which have potential advantages for reducing the number of clinical appointments and simplifying laboratory procedures. Evidence from clinical trials is scarce; a randomized controlled trial reported higher patient satisfaction with digital clasp-retained RPDs than with conventional RPDs. CONCLUSIONS: Full-digital RPDs can be fabricated without a gypsum definitive cast. However, the indication for full-digital RPDs is limited to cases with Kennedy Class III/IV partially edentulous arches with several missing teeth. Challenges in digital impression-taking and MMR recording remain to be solved to extend these indications. More evidence from clinical trials is required to evaluate the efficacy and usefulness of digital RPDs.

A systematic review of digital removable partial dentures. Part II: CAD/CAM framework, artificial teeth, and denture base.

PURPOSE: This study comprehensively reviewed the current status of the digital workflow of removable partial dentures (RPDs) and summarized information about the fabrication methods and material properties of the dental framework, artificial teeth, and denture base. STUDY SELECTION: We performed a systematic review of the literature published in online databases from January 1980 to April 2020 regarding RPD fabrication and materials used in the related digital technology. We selected eligible articles, retrieved information regarding digital RPDs, and conducted qualitative/quantitative analyses. In this paper, the computer-aided design/computer-aided manufacturing (CAD/CAM) framework, artificial teeth, and denture base materials are reported. RESULTS: A variety of materials, such as cobalt-chromium alloy, titanium, zirconia, and polyether ether ketone, are used for dental CAD/CAM frameworks. The mechanical strength of the metal materials used for the CAD/CAM framework was superior to that of the cast framework. However, the fitness and surface roughness of the framework and clasp fabricated using a selective laser melting (SLM) method were not superior to those obtained via cast fabrication. Most material properties and the surface roughness of poly methyl methacrylate (PMMA) discs used for digital RPDs were superior to those of heat-cured PMMA. CONCLUSION: The use of a CAD/CAM framework and PMMA disc for digital RPDs offers numerous advantages over conventional RPDs. However, technical challenges regarding the accuracy and durability of adhesion between the framework and denture base remain to be solved. In digital fabrication, human technical factors influence the quality of the framework.