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Purpose: The purpose of this study was to determine the influence of mandibular free-end partial edentulism and the wearing of removable partial dentures in the partially edentulous area on the force exerted on maxillary anterior teeth., Methods: A commercially available jaw model with exchangeable teeth was used. Seven experimental conditions of mandibular free-end edentulism were set up and a distal extension removable partial denture to replace missing posterior teeth was fabricated. Strain gauges were attached to the root surface of the maxillary left central incisor, canine, first premolar and first molar, and the force exerted on them was calculated based on the calibration coefficient. An occlusal load of 49 N was applied and the forces were compared with the Kruskal-Wallis test (P < 0.05)., Results: The force exerted on the maxillary anterior teeth increased significantly as the number of remaining teeth decreased. The force exerted on the maxillary anterior teeth decreased significantly with use of a removable partial denture., Conclusions: When the number of remaining teeth decreases in mandibular free-end partial edentulism, the burden on the maxillary anterior teeth increases. Our findings suggest that for patients with mandibular free-end partial edentulism, wearing a removable partial denture is effective in preserving the remaining teeth by reducing excessive stress., Competing Interests: Declaration of Competing Interest None., (Copyright © 2019. Published by Elsevier Ltd.)

Background: In some cases, a dentist cannot solve the difficulties a patient has with an implant because the implant system is unknown. Therefore, there is a need for a system for identifying the implant system of a patient from limited data that does not depend on the dentist's knowledge and experience. The purpose of this study was to identify dental implant systems using a deep learning method., Methods: A dataset of 1282 panoramic radiograph images with implants were used for deep learning. An object detection algorithm (Yolov3) was used to identify the six implant systems by three manufactures. To implement the algorithm, TensorFlow and Keras deep-learning libraries were used. After training was complete, the true positive (TP) ratio and average precision (AP) of each implant system as well as the mean AP (mAP), and mean intersection over union (mIoU) were calculated to evaluate the performance of the model., Results: The number of each implant system varied from 240 to 1919. The TP ratio and AP of each implant system varied from 0.50 to 0.82 and from 0.51 to 0.85, respectively. The mAP and mIoU of this model were 0.71 and 0.72, respectively., Conclusions: The results of this study suggest that implants can be identified from panoramic radiographic images using deep learning-based object detection. This identification system could help dentists as well as patients suffering from implant problems. However, more images of other implant systems will be necessary to increase the learning performance to apply this system in clinical practice.

Aim: Previous studies on the association between intraoral conditions and mortality in community-dwelling older individuals reported that fewer present teeth (PT) are significant risk factors for mortality. However, how the number of PT relative to the number of functional teeth (FT), including both present and rehabilitated teeth, influences mortality has not been investigated fully. This study examined the impact of the number of FT on mortality among community-dwelling Japanese older adults., Methods: This study was a retrospective, observational and population-based follow-up study, which examined 1188 older individuals who participated in an annual geriatric health examination from 2009 to 2015. The average follow-up period was 1697.0 ± 774.5 days. The primary outcome was all-cause mortality at follow-up. The numbers of PT and FT of each participant were counted during an oral examination. In addition, demographics, clinical variables, blood nutrient markers, physical functions and perceived masticatory function were measured., Results: Kaplan-Meier analysis, followed by a log-rank test, revealed that fewer PT (P < 0.001) and FT (P = 0.002) were significantly associated with a reduced survival rate. Cox's proportional hazard analysis indicated that the number of FT, but not the number of PT, was a significant independent mortality risk factor after adjusting for demographics, clinical variables, nutrient markers and physical functioning (P = 0.036, hazard ratio: 2.089)., Conclusions: Current results suggest that the number of FT more strongly predicts all-cause mortality than the number of PT among community-dwelling older adults. Further studies are necessary to consider the confounding of socioeconomic status and disability status. Geriatr Gerontol Int 2020; ••: ••-••., (© 2020 The Authors. Geriatrics & Gerontology International published by John Wiley & Sons Australia, Ltd on behalf of Japan Geriatrics Society.)

Background/aim: A mouthguard should be replaced when it deteriorates or becomes deformed as a result of the softness or flexibility of the material. The question, however, is how long can one use a mouthguard and when should one replace it with a newly made mouthguard? The aim of this study was to develop an improved method for measuring the fit of mouthguards based on previous reports and to examine its reliability., Material and Methods: Silicone fit-testing material was applied to the inner surface of the mouthguards of 12 participants, and the mouthguards were inserted into the participants' oral cavity. After the test material had set, the mouthguard was weighed. The intra-rater reliability and inter-rater reliability were analyzed using intraclass correlation coefficients., Results: The intra-rater reliability was 0.813 (P < .001), and the inter-rater reliability was 0.817 (P < .001). Both values were greater than 0.7, suggesting that this measuring method had sufficient reliability., Conclusions: The results of this study indicate that mouthguard fit can be evaluated longitudinally to determine the optimal time to replace a mouthguard., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Gastrointestinal bleeding (GIB) is a common complication of left ventricular assist device (LVAD) therapy accounting for frequent hospitalizations and high resource utilization., Methods: We previously developed an endoscopic algorithm emphasizing upfront evaluation of the small bowel and minimizing low-yield procedures in LVAD recipients with GIB. We compared the diagnostic and therapeutic yield of endoscopy, health-care costs, and re-bleeding rates between conventional GIB management and our algorithm using chi-square, Fisher's exact test, Wilcoxon-Mann-Whitney, and Kaplan-Meier analysis., Results: We identified 33 LVAD patients with GIB. Presentation was consistent with upper GIB in 20 (61%), lower GIB in 5 (15%), and occult GIB in 8 (24%) patients. Forty-one endoscopies localized a source in 23 (56%), resulting in 14 (34%) interventions. Algorithm implementation compared with our conventional cohort was associated with a 68% increase in endoscopic diagnostic yield (P< .01), a 113% increase in therapeutic yield (P= .01), a 27% reduction in the number of procedures per patient (P < .01), a 33% decrease in length of stay (P < .01), and an 18% reduction in estimated costs (P < .01). The same median number of red blood cell transfusions were used in the 2 cohorts, with no increase in re-bleeding events in the algorithm cohort (33.3%) compared with our conventional cohort (43.7%)., Conclusions: Our endoscopic management algorithm for GIB in LVAD patients proved effective in reducing low-yield procedures, improving the diagnostic and therapeutic yield of endoscopy, and decreasing health-care resource utilization and costs, while not increasing the risk of a re-bleeding event., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Volumetric laser endomicroscopy (VLE) uses optical coherence tomography (OCT) for real-time, microscopic cross-sectional imaging. A US-based multi-center registry was constructed to prospectively collect data on patients undergoing upper endoscopy during which a VLE scan was performed. The objective of this registry was to determine usage patterns of VLE in clinical practice and to estimate quantitative and qualitative performance metrics as they are applied to Barrett's esophagus (BE) management. All procedures utilized the NvisionVLE Imaging System (NinePoint Medical, Bedford, MA) which was used by investigators to identify the tissue types present, along with focal areas of concern. Following the VLE procedure, investigators were asked to answer six key questions regarding how VLE impacted each case. Statistical analyses including neoplasia diagnostic yield improvement using VLE was performed. One thousand patients were enrolled across 18 US trial sites from August 2014 through April 2016. In patients with previously diagnosed or suspected BE (894/1000), investigators used VLE and identified areas of concern not seen on white light endoscopy (WLE) in 59% of the procedures. VLE imaging also guided tissue acquisition and treatment in 71% and 54% of procedures, respectively. VLE as an adjunct modality improved the neoplasia diagnostic yield by 55% beyond the standard of care practice. In patients with no prior history of therapy, and without visual findings from other technologies, VLE-guided tissue acquisition increased neoplasia detection over random biopsies by 700%. Registry investigators reported that VLE improved the BE management process when used as an adjunct tissue acquisition and treatment guidance tool. The ability of VLE to image large segments of the esophagus with microscopic cross-sectional detail may provide additional benefits including higher yield biopsies and more efficient tissue acquisition. Clinicaltrials.gov NCT02215291., (© The Author(s) 2019. Published by Oxford University Press on behalf of International Society for Diseases of the Esophagus.)

Purpose: The purpose of this study was to evaluate the biomechanical effects of bone loss on peri-implant bending strain underneath overdentures., Materials and Methods: One mandibular and one maxillary edentulous model were created and covered with 2 to 4 mm of silicone rubber to simulate the oral mucosa. Four strain gauges were attached to four sides of each implant. In the mandibular model, two implants were inserted, and the implant was placed bilaterally in the area between the mandibular canines and lateral incisors. A maxillary conventional denture and mandibular overdenture were fabricated with acrylic resin to fit the edentulous models. Five bone loss levels were created: no bone loss, 0.8 mm bone loss on only the left implant, 0.8 mm bone loss bilaterally, 1.5 mm bone loss on only the left implant, and 1.5 mm bone loss bilaterally. Magnetic attachments were used to retain the denture. The bending strains generated from three types of unilateral loading were measured by a sensor interface, and the data were analyzed using the Kruskal-Wallis test and Bonferroni's post hoc test., Results: Bending strain increased with decreasing bone levels on the loading side. On the nonloading side, bending strains were greater at even bone loss (0.8 mm or 1.5 mm bone loss bilaterally) than at uneven bone loss (0.8 mm or 1.5 mm bone loss on only the left implant). Strains under loading at the left first premolar were approximately equal to that under loading with a cotton roll; these strains were higher than those generated with loading at the left first molar., Conclusion: Peri-implant bending strains rapidly increased on the loading side as bone loss levels increased. Peri-implant bending strains on the nonloading side were higher at bilaterally even bone loss than at unilateral bone loss.

Naringenin is one of the most abundant dietary flavonoids exerting several beneficial biological activities. Synthetic modification of naringenin is of continuous interest. During this study our aim was to synthesize a compound library of oxime and oxime ether derivatives of naringenin, and to investigate their biological activities. Two oximes and five oxime ether derivatives were prepared; their structure has been elucidated by NMR and high-resolution mass spectroscopy. The antiproliferative activity of the prepared compounds was evaluated by MTT assay against human leukemia (HL-60) and gynecological cancer cell lines isolated from cervical (HeLa, Siha) and breast (MCF-7, MDA-MB-231) cancers. Tert -butyl oxime ether derivative exerted the most potent cell growth inhibitory activity. Moreover, cell cycle analysis suggested that this derivative caused a significant increase in the hypodiploid (subG1) phase and induced apoptosis in Hela and Siha cells, and induced cell cycle arrest at G2/M phase in MCF-7 cells. The proapoptotic potential of the selected compound was confirmed by the activation of caspase-3. Antioxidant activities of the prepared molecules were also evaluated with xanthine oxidase, DPPH and ORAC assays, and the methyl substituted oxime ether exerted the most promising activity.

Purpose: To clarify the relationship between the pressure generated during impressions (impression pressure) and the presssure beneath the corresponding denture base (functional pressure) and to examine the influence of tray modifications., Materials and Methods: Impression and functional pressures were measured on models with the same appearance but different bone morphologies for comparison. Pressures with modified trays with additional relief and escape holes were also measured for comparison., Results: The correlation between impression pressure and functional pressure was high, and both could be changed by tray modifications., Conclusion: The distribution of impression pressure will be recreated beneath the denture base, and modifications of trays can control the pressure distribution.

Purpose: The purpose of this study was to determine the optimal positioning of implants for maxillary implant-supported overdentures (MIODs) using finite element analysis (FEA)., Materials and Methods: Three-dimensional (3D) finite element models were built incorporating the maxilla, mucous membrane, removable denture, and artificial teeth using FEA software. Four models were prepared: one without an implant; one with two implants in the region of the lateral incisor; one with two implants in the first premolar region; and one with four implants in the lateral incisor and first premolar regions. Occlusal load was applied to the model, and denture displacement and the distribution of stress in the surrounding bone and mucous membrane were observed and measured., Results: The maximum equivalent stresses to the bone and mucous membrane were highest in the premolar and anterior areas, respectively. Stress to the bone was concentrated around the implants, whereas stress in the mucous membrane was concentrated along the posterior margin. Denture displacement in the anterior direction was highest in the model without implants, while denture displacement in the posterior direction was less affected by the presence of implants. Overall, denture displacement in the four-implant model was smaller than that in the other models. Implant angle affected the stress distribution, with highest stress to the bone when the implant was positioned in a palatal direction and highest stress to the mucous membrane when placed mesially. However, implant angle had little impact on denture displacement, with almost the same stress for implants at all tested angles., Conclusion: Optimal implant position can stabilize overdentures and reduce stress to the bone and mucous membrane. Stress is reduced when implants are inserted in the premolar area and when the direction of the implant is perpendicular to the occlusal plane.

Purpose: To clarify the relationship between residual ridge morphology and pressure distribution of the alveolar bone surface during dental impression procedures., Materials and Methods: Seven experimental models of the mandibular posterior residual ridge with the same ridge morphology but different mucosa (ie, silicone material) thicknesses and bone (ie, plaster) shapes and sizes were fabricated. The pressure on the bone surface was recorded using a pressure sensor sheet. The data from each model were compared using the Kruskal-Wallis test, and P < .05 was considered statistically significant., Results: Even with the same ridge morphology, the distribution of the impression pressure on the bone surface differed according to the mucosal thickness and bone shape and size. Pressure tended to concentrate on sharp edges and prominences of a slope and became more widely distributed as the mucosal thickness increased., Conclusion: Within the limitations of this experimental study, the morphology of the residual alveolar ridge (bone and mucosa) appears to be a significant influencing factor for the pressure distribution during impression procedures.

Purpose: To evaluate the long-term effects of preventive measures against denture fracture using clinical surveys of denture fracture cases from 1984 and 2009., Materials and Methods: This study included 128 patients who presented with a chief complaint of denture fracture and received denture repair treatment in 2009. The following data were collected: denture repair procedure; location of denture base fracture (with or without reinforcement); and period of denture use from insertion to repair. Significant differences in characteristics between patients treated in 1984 and 2009 were determined using the chi-square test (P < .05)., Results: In 2009, denture fractures comprised 55.5% of all repair cases. The most frequent location of denture fracture was around the clasp and metal in the denture base. Approximately 45% of all dentures were reinforced. The mean period from denture insertion to repair was 37 months. The number of denture fractures significantly decreased between 1984 and 2009 (P < .05), and the number of dentures with reinforcement significantly increased (P < .05). The mean period from denture insertion to repair also increased., Conclusion: These findings suggest that denture reinforcement as a preventive measure is effective against denture fracture, allowing patients to use their dentures more effectively.

Background/aim: The mouthguard (MG) is an effective device to reduce the risk of dental traumatic injuries, but the mechanical effects of wearing a MG and its design are not fully understood. The aim of this study was to evaluate the mechanical influence of wearing a MG and its palatal design on the tooth-periodontal ligament-bone complex (TPBC) by computational analysis using the finite element method., Material and Methods: Three-dimensional subject-specific geometry of the TPBC was reconstructed from medical computed tomography (CT) images. Two patterns of MG geometries were constructed which covered the palatal domain or not (the position of these palatal margins was set at -8 mm (pattern 1) and 4 mm (pattern 2) from the cervical line. Five cases of static mechanical analysis were conducted by changing the location of the loading points from near the cervical line to the tip of the tooth., Results: Wearing a MG decreased strain concentration around the loading point and cervical domain regardless of the MG palatal design. Elastic energy in the periodontal ligament (PDL) and tooth (including enamel and dentin) decreased when the MG was worn, whereas the MG palatal design slightly affected the degree of reduction in the elastic energies. The location of the loading points remarkably affected the elastic energy in the TPBC components and the extent of its reduction due to the MG., Conclusions: These findings indicated that the protection ability of the MG exerted in the restricted situations of traumatic events occurs regardless of the MG design., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Gastrointestinal bleeding (GIB) is a frequent cause of re-admission in patients with continuous-flow left ventricular assist devices (CF-LVADs) and is associated with multiple endoscopic procedures and high resource utilization. Our aim was to determine the diagnostic and therapeutic yield of endoscopy and to develop a more cost-effective approach for the management of GIB in CF-LVAD recipients., Methods: We retrospectively reviewed 428 patients implanted with a CF-LVAD between 2009 and 2016 at the Columbia University Medical Center and identified those hospitalized for GIB. Patients were categorized into upper GIB (UGIB), lower GIB (LGIB) and occult GIB (OGIB), based on clinical presentation., Results: Eighty-seven CF-LVAD patients underwent a total of 164 GIBs, resulting in 239 endoscopies. Index presentation was consistent with UGIB in 30 (34.5%), LGIB in 19 (21.8%) and OGIB in 38 (43.7%) patients. On the first GIB, 147 endoscopies localized a bleeding source in 49 (30%), resulting in 24 (16.3%) endoscopic interventions. Of 45 lesions identified, arteriovenous malformations (AVMs) were the most common (22, 48.9%). A gastric or small bowel source (HR 2.8, p = 0.003) and an endoscopic intervention (HR 1.9, p = 0.04) predicted recurrent GIB. The proposed algorithm may reduce the number of endoscopic procedures by 45% and costs by 35%., Conclusions: Occult GIB is the most common presentation in CF-LVAD patients and carries the lowest diagnostic and therapeutic yield of endoscopy. Performing an intervention was among the strongest predictors of recurrent GIB. Our proposed algorithm may decrease the number of low-yield procedures and improve resource utilization., (Copyright © 2018 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

CXC ligand (L)12 is a chemokine implicated in the migration, invasion and metastasis of cancer cells via interaction with its receptors CXC chemokine receptor (CXCR)4 and CXCR7. In the present study, CXCL12-mediated Ca 2+ signalling was compared with two basal-like breast cancer cell lines, MDA-MB-231 and MDA-MB-468, which demonstrate distinct metastatic potential. CXCL12 treatment induced Ca 2+ responses in the more metastatic MDA-MB-231 cells but not in the less metastatic MDA-MB-468 cells. Assessment of mRNA levels of CXCL12 receptors and their potential modulators in both cell lines revealed that CXCR4 and CXCR7 levels were increased in MDA-MB-231 cells compared with MDA-MB-468 cells. Cluster of differentiation (CD)24, the negative regulator of CXCL12 responses, demonstrated increased expression in MDA-MB-468 cells compared with MDA-MB-231 cells, and the two cell lines expressed comparable levels of hypoxia-inducible factor (HIF)2α, a CXCR4 regulator. Induction of epithelial-mesenchymal transition (EMT) by epidermal growth factor exhibited opposite effects on CXCR4 mRNA levels compared with hypoxia-induced EMT. Neither EMT inducer exhibited an effect on CXCR7 expression, however hypoxia increased HIF2α expression levels in MDA-MB-468 cells. Analysis of the gene expression profiles of breast tumours revealed that the highest expression levels of CXCR4 and CXCR7 were in the Claudin-Low molecular subtype, which is markedly associated with EMT features.

A literature review of finite element analysis (FEA) studies of dental implants with their model validation process was performed to establish the criteria for evaluating validation methods with respect to their similarity to biological behavior. An electronic literature search of PubMed was conducted up to January 2017 using the Medical Subject Headings "dental implants" and "finite element analysis." After accessing the full texts, the context of each article was searched using the words "valid" and "validation" and articles in which these words appeared were read to determine whether they met the inclusion criteria for the review. Of 601 articles published from 1997 to 2016, 48 that met the eligibility criteria were selected. The articles were categorized according to their validation method as follows: in vivo experiments in humans (n = 1) and other animals (n = 3), model experiments (n = 32), others' clinical data and past literature (n = 9), and other software (n = 2). Validation techniques with a high level of sufficiency and efficiency are still rare in FEA studies of dental implants. High-level validation, especially using in vivo experiments tied to an accurate finite element method, needs to become an established part of FEA studies. The recognition of a validation process should be considered when judging the practicality of an FEA study.

Purpose: Palateless maxillary implant overdentures are often used for patients experiencing problems with a full-palate denture. However, palateless overdentures are reported to be a risk factor for implant complications. The purpose of this study was to examine the strain on implants beneath palateless overdentures with unsplinted attachments under various implant distributions., Materials and Methods: A maxillary edentulous model with implants and an experimental palateless overdenture were fabricated. Four strain gauges were attached to each implant, positioned in the anterior, premolar, and molar areas. Three types of unsplinted attachments (ball, locator, and magnet) were set on the implants under various implant distributions. A vertical occlusal load of 98 N was applied through the mandibular complete denture, and the bending strain on the implants was compared using the Kruskal-Wallis test (P = .05)., Results: When comparing the strain among different attachments, those using a magnet attachment were the smallest and those using a ball attachment were the greatest, and this difference was significant in most situations (P < .05). When comparing the strain among different implant distributions, the strain on a four-implant distribution was significantly smaller than that on a two-implant distribution in most situations (P < .05), and those using premolar and molar implants recorded the smallest strain. The strain on implants using a locator attachment tended to be midway between those using ball and magnet attachments, regardless of the implant distribution., Conclusion: In most implant distributions, magnet attachments decrease the strain on implants more than ball and locator attachments. The most favorable unsplinted attachments for use beneath palateless overdentures to decrease the implant strain are magnet attachments and four implants placed in the premolar and molar areas.

Background and Study Aims: Self-expandable metallic stents (SEMS) have been increasingly used in benign conditions (e. g. strictures, fistulas, leaks, and perforations). Fully covered SEMS (FSEMS) were introduced to avoid undesirable consequences of partially covered SEMS (PSEMS), but come with higher risk of stent migration. Endoscopic suturing (ES) for stent fixation has been shown to reduce migration of FSEMS. Our aim was to compare the outcomes of FSEMS with ES (FS/ES) versus PSEMS in patients with benign upper gastrointestinal conditions., Patients and Methods: We retrospectively identified all patients who underwent stent placement for benign gastrointestinal conditions at seven US tertiary-care centers. Patients were divided into two groups: FSEMS with ES (FS/ES group) and PSEMS (PSEMS group). Clinical outcomes between the two groups were compared., Results: A total of 74 (FS/ES 46, PSEMS 28) patients were included. On multivariable analysis, there was no significant difference in rate of stent migration between FS/ES (43 %) and PSEMS (15 %) (adjusted odds ratio 0.56; 95 % CI 0.15 - 2.00). Clinical success was similar [68 % vs. 64 %; P  = 0.81]. Rate of adverse events (AEs) was higher in PSEMS group [13 (46 %) vs. 10 (21 %); P  = 0.03). Difficult stent removal was higher in the PSEMS group (n = 5;17 %) vs. 0 % in the FS/ES group; P  = 0.005., Conclusions: The proportion of stent migration of FS/ES and PSEMS are similar. Rates of other stent-related AEs were higher in the PSEMS group. PSEMS was associated with tissue ingrowth or overgrowth leading to difficult stent removal, and secondary stricture formation. Thus, FSEMS with ES for stent fixation may be the preferred modality over PSEMS for the treatment of benign upper gastrointestinal conditions.

Purpose: The aim of this study was to examine the deformation modality of palateless maxillary implant overdentures using isolated attachments under various implant configurations., Materials and Methods: A maxillary edentulous model with implants inserted in the anterior, premolar, and molar areas was fabricated, and three types of unsplinted attachments-ball, locator, and magnet-were set on the implants distributed in various configurations. Experimental palateless dentures were fabricated, and two strain gauges were attached at the anterior midline of the labial and palatal sides. A vertical occlusal load of 98 N was applied, and the shear strains of dentures were measured. The measurements of strains were compared with the Kruskal-Wallis test (P = .05)., Results: The strains of the labial side were much larger than those of the palatal side except for those using the ball attachment. The strains using the magnet attachment on anterior implants were significantly larger than those using other attachments (P < .05). Those using anterior implants were significantly smaller than those using premolar or molar implants (P < .05)., Conclusion: The strains of palateless overdentures were different according to the attachments and implant distribution. However, when using molar implants, there was no significant difference among the three attachments.

Stereoselective synthesis of monoterpene-based 1,2,4- and 1,3,4-oxadiazole derivatives was accomplished starting from α,β-unsaturated carboxylic acids, obtained by the oxidation of (-)-2-carene-3-aldehyde and commercially available (-)-myrtenal. 1,2,4-Oxadiazoles were prepared in two steps via the corresponding O -acylamidoxime intermediates, which then underwent cyclisation induced by tetrabutylammonium fluoride (TBAF) under mild reaction conditions. Stereoselective dihydroxylation in highly stereospecific reactions with the OsO₄/NMO ( N -methylmorpholine N -oxide) system produced α,β-dihydroxy 1,2,4-oxadiazoles. Pinane-based 1,3,4-oxadiazoles were obtained similarly from acids by coupling with acyl hydrazines followed by POCl₃-mediated dehydrative ring closure. In the case of the arane counterpart, the rearrangement of the constrained carane system occurred with the loss of chirality under the same conditions. Stereoselective dihydroxylation with OsO₄/NMO produced α,β-dihydroxy 1,3,4-oxadiazoles. The prepared diols were applied as chiral catalysts in the enantioselective addition of diethylzinc to aldehydes. All compounds were screened in vitro for their antiproliferative effects against four malignant human adherent cell lines by means of the MTT assay with the O -acylated amidoxime intermediates exerting remarkable antiproliferative action., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results. Sources of funding for the study: Zsolt Szakonyi—OTKA K112442, István Zupkó—OTKA K115731 and Ferenc Fülöp—OTKA K109293, all authors—GINOP-2.3.2-15-2016-00012.

There appears to be much confusion or misinformation worldwide regarding mouthguards and their use in sports. In an effort to clarify where the international dental community stands on mouthguards and mouthguard research, the workshop looked at some important questions. The goal was to one day formulate consensus statements related to these questions, which will be based on current scientific evidence-based research, to motivate the international community of the importance of dentally fitted laminated mouthguards and the wearing of them by athletes of all sports. There are only five sports in the United States that require the use of mouthguards. If, through workshops such as this, the importance of wearing dentally fitted laminated mouthguards can be demonstrated, then more sports may require their athletes to wear them., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The critical role of calcium signalling in processes related to cancer cell proliferation and invasion has seen a focus on pharmacological inhibition of overexpressed ion channels in specific cancer subtypes as a potential therapeutic approach. However, despite the critical role of calcium in cell death pathways, pharmacological activation of overexpressed ion channels has not been extensively evaluated in breast cancer. Here we define the overexpression of transient receptor potential vanilloid 4 (TRPV4) in a subgroup of breast cancers of the basal molecular subtype. We also report that pharmacological activation of TRPV4 with GSK1016790A reduced viability of two basal breast cancer cell lines with pronounced endogenous overexpression of TRPV4, MDA-MB-468 and HCC1569. Pharmacological activation of TRPV4 produced pronounced cell death through two mechanisms: apoptosis and oncosis in MDA-MB-468 cells. Apoptosis was associated with PARP-1 cleavage and oncosis was associated with a rapid decline in intracellular ATP levels, which was a consequence of, rather than the cause of, the intracellular ion increase. TRPV4 activation also resulted in reduced tumour growth in vivo. These studies define a novel therapeutic strategy for breast cancers that overexpress specific calcium permeable plasmalemmal ion channels with available selective pharmacological activators.

Purpose: Implant overdentures with attachments have been used in clinical practice and the effect of attachments on implant strain has been frequently reported. However, most studies have focused on mandibular overdentures; there are few reports on maxillary overdentures. The purpose of this study was to examine the influence of attachment type on implant strain in maxillary overdentures under various implant configurations., Materials and Methods: A maxillary edentulous model with implants and experimental overdentures were fabricated. Four strain gauges were attached to each implant, positioned in anterior, premolar, and molar areas. Three types of unsplinted attachments-ball, locator, and magnet-were set on the implants under various implant configurations. A vertical occlusal load of 98 N was applied through the mandibular complete denture, and implant strain was compared using the Kruskal-Wallis test., Results: Ball attachments caused the greatest amount of strain, while magnet attachments caused the least amount under all conditions. For all attachments, two anterior implants caused significantly more strain than four implants (P < .05). No significant difference was observed between subtypes in four-implant configurations except when using locator attachments., Conclusion: When using unsplinted attachments for maxillary implant overdentures, magnet attachments are recommended to reduce implant stress. Using only two implants, especially two anterior implants, is not recommended regardless of attachment type.

Purpose: The purpose of this preliminary study was to examine the influence of overdenture attachment height and shape on lateral force on implants and denture displacement., Materials and Methods: A straight model was fabricated to simulate the edentulous ridge. Two strain gauges were attached to the mesial and distal surfaces of the implant in the canine area. Five types of ball attachments and three types of Locator attachments with three types of replacement male attachments were used. A vertical load of 49 N was applied. The lateral force on the implant and the denture displacement were measured. Statistical comparisons were performed using one-way analysis of variance, Tukey post hoc comparison test, and multivariate analysis. P < .05 was considered significant., Results: Ball attachments of 4-mm height exerted the highest lateral force on the implant, and the greatest displacement was also observed with attachments of 4-mm height. Different lateral forces were observed for different shapes of ball attachments, but there were no significant differences in denture displacement among the shapes. For Locator attachments, the highest lateral force was observed with the white male type, and the greatest denture displacement occurred with attachments of 4-mm height. There were no significant differences among male white, pink, and blue types., Conclusion: The height of the stud attachments in implant overdentures had a marked effect on the lateral force on implants and on denture displacement. To protect implants supporting an overdenture and to prevent bone resorption, the height of the attachment should be carefully considered.

Purpose: To describe a method for customizing scuba diving mouthpieces, to examine their usability, and to assess divers' satisfaction with their use., Materials and Methods: A rational method for fabricating custom-made mouthpieces for scuba diving was developed. Twenty scuba divers agreed to use a custom-made mouthpiece for at least 4 weeks. After mouthpiece use, participants completed an 11-item questionnaire., Results: Custom-made mouthpieces had significantly lower scores for all items on the questionnaire except uncomfortable sensation, indicating that they were more comfortable than ready-made mouthpieces., Conclusion: It can be concluded that these novel custom-made mouthpieces for scuba diving offer greater comfort than ready-made mouthpieces.

Background: Gastric cancer (GC) is the leading cause of cancer death among Korean Americans. Prevention and early detection is improved by screening., Methods: Between September 2013 and March 2015, ethnic Koreans age 40 or older without history or symptoms of GC and without upper endoscopy (UE) during previous 3 years were enrolled. Participants were offered screening with GC risk assessment followed by UE with biopsies., Results: Risk assessment was provided to 146 participants (age 55.6 ± 8.3 years; 52.1% female; 92.5% uninsured), of whom 99 (67.8%) returned for UE. Undergoing UE was independently associated with family history of GC (OR 12.33, 95% CI:1.52-100.17), being a former smoker (6.68,1.42-31.32), and Hp-negative status (0.25,0.11-0.57). Among UE recipients, half (49.5%) had intestinal metaplasia (IM) only (n = 24), Hp only (n = 12), or both (n = 13). No case of GC was found. Adjusted for age, IM was independently associated with male sex (2.89,1.12-7.42), current Hp (2.90,0.99-8.51), unmarried status (single or divorced) (4.23,1.23-14.56)., Conclusions: High prevalence of risk factors associated with gastric carcinogenesis including Hp infection and IM exists in Korean Americans who underwent upper endoscopic screening. Acceptance of GC screening is informed by personal risk factors. These findings support the need to improve access to screening UE among KAs., (© 2017 Wiley Periodicals, Inc.)

Purpose: This study examined the effects of attachments on strain in maxillary implant overdentures supported by two or four implants., Materials and Methods: A maxillary edentulous model with implants inserted into anterior, premolar, and molar areas was fabricated, and three types of unsplinted attachments-ball, locator, and magnet-were set on the implants distributed under various conditions. Maxillary experimental dentures were fabricated, and two strain gauges were attached at the anterior midline on the labial and palatal sides. A vertical occlusal load of 98 N was applied and shear strain of the dentures was measured., Results: On both sides, magnet attachments resulted in the lowest shear strain, while ball attachments resulted in the highest shear strain under most conditions. However, differences in shear strain among the three attachment types were not significant when supported by four implants, especially molar implants., Conclusion: Shear strain of the maxillary implant overdenture was lowest when using magnet attachments. Magnet attachments mounted on four implants are recommended to prevent denture complications when using maxillary implant overdentures.

Purpose: The aim of this study was to determine the optimal number and location of mini-implants retaining an overdenture to resist lateral forces., Materials and Methods: A strain gauge was attached to a mini-implant and placed in an edentulous mandible model. The following different implant locations were evaluated: one mini-implant at the midline, two mini-implants in the lateral incisor regions, two mini-implants in the canine regions, and four mini-implants., Results: Lateral forces on mandibular overdentures retained by one mini-implant at the midline or two mini-implants in the lateral incisor regions appeared to be advantageous when compared with placing two mini-implants in the canine regions or four mini-implants., Conclusion: Fewer mini-implants resulted in less lateral stress, while four were associated with an unequal stress distribution.

Removable prosthodontics are often associated with mechanical troubles in daily use, such as fracture or deformation. These troubles render prostheses unusable and reduce wearers' QOL. Various reinforcements are used to prevent such problems, but consensus on reinforcement has not been reached. This review aimed to summarise the effects of reinforcement and to propose favourable reinforcement based on material, design and position in the prostheses. Initially, 139 articles were selected by electronic and manual searches. After exclusion of 99 articles based on the exclusion criteria, 40 articles were finally included in the review. Electronic searches were performed for articles published from 2005 to 2015 in PubMed, EMBASE, MEDLINE and Cochrane Library, and manual searches were performed in 10 journals relevant to the topic of removable prosthodontics. For in vitro studies, certain dental alloys and fibres were mainly used. Their forms were different, including complicated forms in dental alloys and various forms in fibres. The materials were examined for mechanical properties like fracture strength, flexural strength and elastic modulus and compared with one another or without reinforcement. There were a few clinical studies and one longitudinal study. Cast metal reinforcement seemed to be most favourable in terms of fracture toughness and stiffness. The most favourable forms differed depending on the prostheses, but placement around thin and deformable areas was effective. However, randomised or longitudinal clinical reports and comparative clinical studies on the use of reinforcement were still lacking and such studies are necessary in the future., (© 2016 John Wiley & Sons Ltd.)

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has resulted in the contamination of the environment in Gunma Prefecture with radioisotope cesium (radio-Cs, 134 Cs and 137 Cs). Concentrations of radio-Cs >500Bqkg -1 were found in wakasagi (Hypomesus nipponensis) in Lake Onuma at the top of Mount (Mt.) Akagi in August 2011. To explain the mechanism of this contamination, monitoring studies have been conducted around Lake Onuma by measuring radio-Cs concentrations in samples of fish, aquatic plants, plankton, lake water, lake sediments, and surrounding soil. The leachability of radio-Cs was evaluated using sequential extraction by Tessier et al. The total concentration of radio-Cs in Lake Onuma ecosystems decreased gradually with time. In the brown forest soil, radio-Cs concentrations of 2000 to 6000Bqkg -1 were detected. The abundance ratio of the easy-elution form (exchangeable and carbonate forms) in the samples was <10%. The concentrations in phytoplankton samples were 3-6 times higher than those in wakasagi samples. The ratios of easy-elution forms increased by the rank in the food chain; 37% in phytoplankton, 78% in zooplankton, and 97% in wakasagi. It is likely that the lower ratio of the easy-elution form in phytoplankton is related to the adsorption of radio-Cs on suspended substances in the lake, as suggested by the analyses of aluminum and titanium in the phytoplankton, zooplankton, and wakasagi samples. The high concentrations of radio-Cs in wakasagi would be related also to the characteristics of closed mountain lakes., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Purpose: Success rates for maxillary implant treatment are lower than for mandibular treatment because of the presence of poorer bone quality or quantity in the maxilla. The purpose of this study was to determine favorable implant positions in the maxilla using implant simulation software and clinical anatomical morphology together with bone quality data obtained by computed tomography (CT)., Materials and Methods: A convenience research sample of 10 edentulous subjects was recruited, and research information from right and left edentulous sites was obtained from each subject. The height, width, angulation, and Hounsfield unit value of the maxillary alveolar bone were measured using CT data obtained from the subjects., Results: Bone height in the incisor area was significantly greater than in the molar area, and bone width in the incisor area was significantly narrower than in the molar area. The average bone quality in the maxillary molar area was significantly higher when compared with the premolar and incisor areas. The angle between the occlusal plane and the bisector of the alveolar bone in the incisor area was reduced when compared with the molar area., Conclusion: The premolar region appears to be the most favorable area in the maxillary arch for implant placement with regard to bone height, width, angulation, and quality.

Purpose: Reinforcement of maxillary implant overdentures is necessary not only for preventing prosthetic complications but also for protecting underlying structures, as it makes the denture base more rigid. However, few studies have investigated the effects of reinforcement on the underlying structure. The purpose of this study was to examine the effects of reinforcement on implant stress under various implant configurations and denture designs., Materials and Methods: A maxillary edentulous model with implants and experimental overdentures with and without palatal coverage and three types of cast reinforcement was fabricated. Four strain gauges were attached to the implants in the anterior, premolar, and molar areas. A vertical occlusal load of 98 N was applied through the mandibular complete denture, and the strain on the implants was compared using one-way analysis of variance (P = .05)., Results: In dentures with palatal coverage, reinforcement significantly decreased the strain on the anterior and molar implants. In palateless dentures, reinforcement with a palatal bar decreased the strain most on the anterior and molar implants., Conclusion: Reinforcement of maxillary implant overdentures decreased the strain on underlying implants, regardless of the denture design and implant configurations.

Purpose: This study evaluated the impact of angled abutments on strain in implants supporting a distal extension removable partial denture., Materials and Methods: An in vitro model of an implant supporting a distal extension removable partial denture was developed. The implant was positioned with a 17- or 30-degree mesial inclination, with either a healing abutment or a corrective multiunit abutment. Levels of strain under load were compared, and the results were compared using t test (P = .05)., Results: Correcting angulation with a multiunit angled abutment significantly decreased strain (P < .05) when compared with a healing abutment., Conclusion: An angled abutment decreased the strain on an inclined implant significantly more than a healing abutment when loaded under a distal extension removable partial denture.

Purpose: Maxillary implant overdentures are often designed without palatal coverage to maximize wearer comfort. Although palateless dentures have been reported to be less rigid than conventional dentures, and require reinforcement to prevent complications, there is little documentation about the effects of such reinforcement. The purpose of this study was to examine the effects of reinforcement on the strain on maxillary implant overdentures supported by implants in a variety of configurations., Materials and Methods: A maxillary edentulous model with implants inserted in the anterior, premolar, and molar area was fabricated. Five types of experimental overdentures, with and without reinforcement, were fabricated, and two strain gauges were attached at the anterior midline of the labial and palatal sides. A vertical occlusal load of 98 N was applied through a mandibular complete denture, and the shear strain on the denture was measured. The measurements were compared using the Kruskal-Wallis test (P = .05)., Results: On both the labial and palatal sides, the strain on the palateless dentures with reinforcement was significantly lower than the strain on palateless dentures without reinforcement in all implant configurations (P < .05). The labial strain on the palateless dentures with reinforcement was almost as low as the labial strain on dentures with palatal coverage in most implant configurations., Conclusion: Reinforcement of a palateless implant overdenture with residual ridge reinforcement and a palatal bar could reduce the strain in the anterior midline to almost the same level as a denture with palatal coverage. This type of reinforcement may prevent prosthetic and implant complications.

Purpose: To investigate the recent incidence of malignant tumors associated with Peutz-Jeghers syndrome (PJS) in Japan to clarify if there are any differences in malignant tumor risk and the spectrum of malignancies by reviewing the literature on this subject., Methods: We reviewed PJS cases reported in 1115 papers in Japan between January, 1989 and December, 2014., Results: Malignant tumors were identified in 186 of the total 583 PJS cases from 523 evaluable studies. The estimated cumulative risk of a malignant tumor was 83.0 % at 70 years of age. Compared with a previous study, on a collective 91 cases reported up until 1988 in Japan, the reported proportion of gastrointestinal malignancies decreased, from 82.4 to 48.3 %, whereas that of gynecological malignancies increased, from 8.8 to 34.3 % (P < 0.01). Moreover, breast cancers were occasionally reported (4.8 %), even though none were reported in the previous study. Adenocarcinoma of the uterine cervix was the most common malignant tumor (46.8 %) among women with PJS., Conclusions: The increased number of reports of cervical adenocarcinoma in women with PJS is the prominent trend in Japan, and a subject of concern among gynecologists. The risk of breast cancer seems to be increasing, but confirmation of this trend will require further investigation.

Purpose: Maxillary implant overdentures are often used in clinical practice. However, there is no agreement or established guidelines regarding prosthetic design or optimal implant placement configuration. The purpose of this study was to examine the influence of palatal coverage and implant number and distribution in relation to impact strain under maxillary implant overdentures., Materials and Methods: A maxillary edentulous model with implants and experimental overdentures with and without palatal coverage was fabricated. Four strain gauges were attached to each implant, and they were positioned in the anterior, premolar, and molar areas. A vertical occlusal load of 98 N was applied through a mandibular complete denture, and the implant strains were compared using one-way analysis of variance (P = .05)., Results: The palatolabial strain was much higher on anterior implants than on other implants in both denture types. Although there was no significant difference between the strain under dentures with and without palatal coverage, palateless dentures tended to result in higher implant strain than dentures with palatal coverage. Dentures supported by only two implants registered higher strain than those supported by four or six implants., Conclusion: Implants under palateless dentures registered higher strain than those under dentures with palatal coverage. Anterior implants exhibited higher palatolabial strain than other implants regardless of palatal coverage and implant configuration; it is therefore recommended that maxillary implant overdentures should be supported by six implants with support extending to the distal end of the arch.

Background and Study Aims: Fully covered self-expandable metal stents (FCSEMSs) have increasingly been used in benign upper gastrointestinal (UGI) conditions; however, stent migration remains a major limitation. Endoscopic suture fixation (ESF) may prevent stent migration. The aims of this study were to compare the frequency of stent migration in patients who received endoscopic suturing for stent fixation (ESF group) compared with those who did not (NSF group) and to assess the impact of ESF on clinical outcome., Patients and Methods: This was a retrospective study of patients who underwent FCSEMS placement for benign UGI diseases. Patients were divided into either the NSF or ESF group. Outcome variables, including stent migration, clinical success (resolution of underlying pathology), and adverse events, were compared., Results: A total of 125 patients (44 in ESF group, 81 in NSF group; 56 benign strictures, 69 leaks/fistulas/perforations) underwent 224 stenting procedures. Stent migration was significantly more common in the NSF group (33 % vs. 16 %; P = 0.03). Time to stent migration was longer in the ESF group (P = 0.02). ESF appeared to protect against stent migration in patients with a history of stent migration (adjusted odds ratio [OR] 0.09; P = 0.002). ESF was also significantly associated with a higher rate of clinical success (60 % vs. 38 %; P = 0.03). Rates of adverse events were similar between the two groups., Conclusions: Endoscopic suturing for stent fixation is safe and associated with a decreased migration rate, particularly in patients with a prior history of stent migration. It may also improve clinical response, likely because of the reduction in stent migration., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: Root fracture is a common and serious cause of abutment tooth loss. No studies to date have comprehensively assessed the individual contributions of the factors that increase stress on abutment teeth. The purpose of this study was to analyze the stress distribution in abutment teeth based on a three-dimensional finite element model and to analyze the factors that affect stress distribution., Materials and Methods: Models were generated from the computed tomography data of a single patient, consisting of a mandibular second premolar abutment tooth, bone, residual mucous membrane, and a partial removable dental prosthesis (PRDP). Four models were prepared using different types of endodontic posts and cores. Akers clasps were used for the simulated PRDPs, and a vertical load was applied to the occlusal surface of the PRDPs. Debonding between the post and root was simulated. The Young modulus of the residual ridge was reduced to simulate a poor fit between the denture base and the residual ridge. Stress distribution in the abutment tooth root was observed, and the maximum principal stress was evaluated., Results: The nonmetal post model and the mesial rest model reduced stress concentration in the root. The stress increased in models simulating debonding and poor fit. The results of the multiple linear regression analysis confirmed that debonding and poor fit were significantly associated with root stress., Conclusion: Within the limitations of this study, it is suggested that the bonding integrity of posts and adequate fit of the denture base are important factors affecting the longevity of abutment teeth for PRDPs.

Purpose: The partial removable dental prosthesis (PRDP) is used widely to replace missing teeth, but it can disturb the ecology of the mouth. In this retrospective cohort study, the null hypothesis was that there was no difference between tooth loss and the type of edentulous spaces in participants wearing PRDPs., Materials and Methods: Participants were selected from patients who were treated consecutively with PRDPs between January 2003 and December 2006 by undergraduate dental students at the University of British Columbia and attended the clinic for at least 5 years following placement of the PRDP. Clinical records were analyzed for 50 men and 52 women aged 19 to 85 years at baseline, before placement of the PRDP (mean age: 63.2 years). Baseline data were obtained from the records on missing teeth and edentulous spaces, and thereafter data were collected on teeth lost over the following 5-year period. Baseline data on age, sex, occlusal contacts, number of dental rests for the dentures, carious teeth, gingival attachment loss, and teeth with endodontic fillings were also obtained., Results: The presence at baseline of teeth with endodontic fillings significantly (P < .05) increased the prediction of tooth loss over the 5 years, but the type of edentulous space did not., Conclusion: The risk of tooth loss over a 5-year period was higher in the presence of endodontically treated teeth, but no higher in participants wearing PRDPs with distally extended edentulous spaces rather than tooth-bounded edentulous spaces.

Goals: To describe a multicenter experience using an endoscopic suturing device for management of gastrointestinal (GI) defects and stent anchorage., Background: Endoscopic closure of GI defects including perforations, fistulas, and anastomotic leaks as well as stent anchorage has improved with technological advances. An endoscopic suturing device (OverStitch; Apollo Endosurgery Inc.) has been used., Study: Retrospective study of consecutive patients who underwent endoscopic suturing for management of GI defects and/or stent anchorage were enrolled between March 2012 and January 2014 at multiple academic medical centers. Data regarding demographic information and outcomes including long-term success were collected., Results: One hundred and twenty-two patients (mean age, 52.6 y; 64.2% females) underwent endoscopic suturing at 8 centers for stent anchorage (n=47; 38.5%), fistulas (n=40; 32.7%), leaks (n=15; 12.3%), and perforations (n=20; 16.4%). A total of 44.2% underwent prior therapy and 97.5% achieved technical success. Immediate clinical success was achieved in 79.5%. Long-term clinical success was noted in 78.8% with mean follow-up of 68 days. Clinical success was 91.4% in stent anchorage, 93% in perforations, 80% in fistulas, but only 27% in anastomotic leak closure., Conclusions: Endoscopic suturing for management of GI defects and stent anchoring is safe and efficacious. Stent migration after stent anchoring was reduced compared with published data. Long-term success without further intervention was achieved in the majority of patients. The role of endoscopic suturing for repair of anastomotic leaks remains unclear given limited success in this retrospective study.

Purpose: As maxillary implant overdentures are being increasingly used in clinical practice, prosthodontic complications related to these dentures are also reported more often. The purpose of this study was to examine the influence of palatal coverage and implant distribution on the shear strain of maxillary implant overdentures., Materials and Methods: A maxillary edentulous model with implants inserted in the anterior, premolar, and molar areas was fabricated. Two kinds of experimental overdentures, with and without palatal coverage, were also fabricated, and two strain gauges were attached at the midline of the labial and palatal sides. A vertical occlusal load of 98 N was applied through a mandibular complete denture, and the shear strain in each denture was compared by analysis of variance (P = .05)., Results: In all situations, the shear strain in palateless dentures was significantly higher than in dentures with palate on both sides (P < .05). In dentures with palate, the shear strain was lower when anterior implants were present., Conclusion: Palateless maxillary implant overdentures exhibited much higher strain than overdentures with palate regardless of the implant distribution; this may cause more prosthodontic and implant complications. The most favorable configuration to prevent complications in maxillary implant overdentures was palatal coverage that was supported by more than four widely distributed implants.

Pancreatic ductal adenocarcinoma (PDAC) and cholangiocarcinoma (CCA) are two malignancies that carry significant morbidity and mortality. The poor prognoses of these cancers are strongly related to lack of effective screening modalities as well as few therapeutic options. In this review, we highlight novel biomarkers that have the potential to be used as diagnostic, prognostic and predictive markers. The focus of this review is biomarkers that can be evaluated on endoscopically-obtained biopsies or brush specimens in the pre-operative setting. We also provide an overview of novel serum based markers in the early diagnosis of both PDAC and CCA. In pancreatic cancer, the emphasis is placed on prognostic and theranostic markers, whereas in CCA the utility of molecular markers in diagnosis and prognosis are highlighted.

Purpose: The aim of this study was to investigate strain on implants used for adjunctive support of distal extension removable partial dentures., Materials and Methods: An implant with strain gauges was used for testing purposes in two positions, parallel and inclined. Three loading scenarios--loading apparatus (LA), artificial teeth via cotton roll (CR), and artificial teeth (UT)--were studied and strains compared via the Kruskal-Wallis test (P=.05)., Results: Strain under CR was significantly larger than UT in parallel (P<.05). However, the opposite was observed in inclined., Conclusions: Strain in parallel was smallest for UT, whereas in inclined it was largest for CR.

Purpose: The purpose of this study was to examine the influence of reinforcement of an embedded cast on the strains within maxillary implant overdentures., Materials and Methods: A maxillary edentulous model with implants placed bilaterally in the canine positions, dome-shaped copings, and experimental overdentures was fabricated. Rosette-type strain gauges were attached in the canine positions and at three points along the midline of the polished surface of the denture and connected to the sensor interface controlled by a personal computer. Experimental dentures with five different reinforcements were tested: without reinforcement; with a cast cobalt-chrome reinforcement over the residual ridge and the tops of the copings; with the same reinforcement from first molar to first molar, over the residual ridge and the tops of the copings; with the same reinforcement over the residual ridge and the sides of the copings; and with the same reinforcement from first molar to first molar, over the residual ridge and the sides of the copings. A vertical occlusal load of 49 N was applied to the first premolar and then to the first molar, and the strains were measured and compared by analysis of variance., Results: In both loading situations, significantly less strain was recorded in dentures with reinforcement than in those without reinforcement. When the first premolar was loaded on dentures with and without palatal reinforcement at the first premolars, the strains on the denture with reinforcement over the tops of the copings were significantly lower than on the denture with reinforcement over the sides of the copings at the canine position., Conclusion: Cast reinforcement over the residual ridge and the top of copings embedded in an acrylic base reduced the strain from occlusal stress on maxillary implant overdentures.

Objective: Lateral force to mini-implants should be avoided because mini-implants are weak mechanically because of its small diameter. Overdentures retained by mini-implants are usually formed using ball attachments. However, bar attachments can offer the advantage of splinting the mini-implants. This study examined the effect of attachments in withstanding these lateral forces in tilted mini-implants of overdentures., Materials and Methods: Strain gauges were attached to the mini-implants (2.5 × 18 mm) embedded in an acrylic resin block. Two mini-implants were inserted vertically (Control) or with one mini-implant inclined at 10° or 20° (10-inclined and 20-inclined, respectively). The female portions of the attachments were secured to the denture base. A prefabricated ball attachment and CAD/CAM-fabricated bar attachment were compared. A vertical load of 49 N was applied to the occlusal surface at a distance 10 mm away from the center of two mini-implants. The lateral force borne by the mini-implants was measured via the attached strain gauge. Mann-Whitney U-test and an analysis of Bonferroni correction were used to compare differences between the two attachments and among the three models (P < 0.05)., Results: The lateral force exerted to the inclined mini-implant was significantly greater than that borne by a vertical mini-implant for both attachment types. The lateral force on the 20° inclined mini-implants with bar attachments was smaller than that on mini-implants with ball attachments., Conclusion: Inclined mini-implants are subjected to greater stresses than vertical ones, and a bar attachment can reduce the lateral forces borne by the mini-implant when one mini-implant inclined at 20°., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: The purpose of this study was to determine the implant stress under distalextension removable prostheses (DERPs)., Materials and Methods: A mandibular distal-extension cast and denture were fabricated. Strain gauges were attached to the implant, which was placed either parallel to the distal abutment or perpendicular to the ridge crest (inclined). Occlusal load was applied in five directions, and strains were compared using the Kruskal-Wallis test (P = .05)., Results: When the implant was parallel, the strain was maximum at 20 degrees applied load direction. When the implant was inclined, the strain was minimum at 20 degrees mesial and maximum at 20 degrees applied distal load direction., Conclusions: Implant bending strain is reduced when the implant is loaded on its long axis and oriented parallel with the long axis of the most distal tooth.

This preliminary study examined laboratory-simulated differences between maxillary complete dentures with and without a palate (palateless) as well as the effect of reinforcement of the latter design. Five types of experimental dentures and three types of reinforcements were made. Strain gauges were attached, and a vertical load was applied. The strain was statistically compared using analysis of variance (P = .05). Strain recordings on the palatal side of palateless dentures without reinforcement were significantly higher than in complete dentures and palateless dentures with reinforcement (P < .05). These preliminary observations suggest that such reinforcement with a palatal bar or metal-based palate may reduce the risk of fracture and deformation.

Purpose: Although the risks of using a cantilever to treat missing teeth have been described, the mechanisms remain unclear. This study aimed to reveal these mechanisms from a biomechanical perspective. The effects of various implant sites, number of implants, and superstructural connections on stress distribution in the marginal bone were analyzed with three-dimensional finite element models based on mandibular computed tomography data. Forces from the masseter, temporalis, and internal pterygoid were applied as vectors., Materials and Methods: Two three-dimensional finite element models were created with the edentulous mandible showing severe and relatively modest residual ridge resorption. Cantilevers of the premolar and molar were simulated in the superstructures in the models. The following conditions were also included as factors in the models to investigate changes: poor bone quality, shortened dental arch, posterior occlusion, lateral occlusion, double force of the masseter, and short implant. Multiple linear regression analysis with a forced-entry method was performed with stress values as the objective variable and the factors as the explanatory variable., Results: When bone mass was high, stress around the implant caused by differences in implantation sites was reduced. When bone mass was low, the presence of a cantilever was a possible risk factor. The stress around the implant increased significantly if bone quality was poor or if increased force (eg, bruxism) was applied., Conclusion: The addition of a cantilever to the superstructure increased stress around implants. When large muscle forces were applied to a superstructure with cantilevers or if bone quality was poor, stress around the implants increased.