Effect of three investing materials on tooth movement during flasking procedure for complete denture construction

Problem statement

Tooth movement has been shown to occur during and after the processing of complete dentures. An understanding of this phenomenon may permit one to construct functional complete dentures that require less occlusal adjustment in the articulator and in the patient’s mouth.

Purpose

The purpose of this study was to examine the effects of three different investing methods on tooth movement occurring during the processing of simulated maxillary complete dentures.

Material and methods

Forty-five similar maxillary dentures were made using heat-polymerized acrylic resin, and assigned randomly to three experimental groups (n = 15 each) according to investing method: plaster–plaster–plaster (P–P–P), plaster–stone–stone (P-S-S), and plaster–mix (P–M). Specimens in all experimental groups were compression molded with denture base resin. Transverse interincisor (I–I) and intermolar (M–M) distances, and anteroposterior incisor–molar (LI–LM and RI–RM) distances, were measured with digital calipers at the wax denture stage (pre-polymerization) and after denture decasting (post-polymerization). Analysis of variance and Tukey’s test were used to compare the results.

Results

M–M, LI–LM, and RI–RM movement was significantly greater in the P–P–P group than in the P–S–S and P–M groups; no significant difference in I–I movement was observed among groups. Transverse movement along M–M and I–I was significantly greater than anteroposterior movement in the P–P–P group; no significant difference among measurements was observed in the other two groups.

Conclusion

The study results indicate that the use of dental stone or a 50:50 mixture of plaster and stone for investing of dentures is an important factor in efforts to control the magnitude of tooth movement.     

A humid corridor across the Sahara for the migration of early modern humans out of Africa 120,000 years ago

It is widely accepted that modern humans originated in sub-Saharan Africa approximately 150-200 thousand years ago (ka), but their route of dispersal across the currently hyperarid Sahara remains controversial. Given that the first modern humans north of the Sahara are found in the Levant approximately 120-90 ka, northward dispersal likely occurred during a humid episode in the Sahara within Marine Isotope Stage (MIS) 5e (130-117 ka). The obvious dispersal route, the Nile, may be ruled out by notable differences between archaeological finds in the Nile Valley and the Levant at the critical time. Further west, space-born radar images reveal networks of-now buried-fossil river channels that extend across the desert to the Mediterranean coast, which represent alternative dispersal corridors. These corridors would explain scattered findings at desert oases of Middle Stone Age Aterian lithic industries with bifacial and tanged points that can be linked with industries further to the east and as far north as the Mediterranean coast. Here we present geochemical data that demonstrate that water in these fossil systems derived from the south during wet episodes in general, and penetrated all of the way to the Mediterranean during MIS 5e in particular. This proves the existence of an uninterrupted freshwater corridor across a currently hyperarid region of the Sahara at a key time for early modern human migrations to the north and out of Africa.     

miR-10b-5p Rescues Diabetes and Gastrointestinal Dysmotility

1. Download : Download high-res image (380KB)
2. Download : Download full-size image

     

Ischemic changes in the pancreas of Watanabe heritable hyper-lipidemic (WHHL) rabbits

Summary Arterial intimal thickening and thrombosis of the pancreatic artery has frequently been found in Watanabe heritable hyper-lipidemic (WHHL) rabbits. Three of the 20 rabbits used in this study showed histopathological findings such as intra- or interlobular fibrosis with lymphocytic infiltration, acinar degenerative changes, ductular proliferation and small ductal dilatations which were identical to those of human chronic pancreatitis. These findings were observed in discrete areas clearly demarcated from normal pancreatic parenchyma and adjacent to parenchymal necrosis. These discrete areas were developed just peripheral to regions of necrotic or inflammatory obstruction of the pancreatic duct, which might have been caused by parenchymal necrosis due to severe ischemia. The stasis of pancreatic juice in the ductal tree may result in such findings in the WHHL rabbit. Fat replacement of pancreatic parenchyma was observed in 17 of the 20 WHHL rabbits, and was classified into two types, diffuse and massive. Massive fat replacement may occur from fat necrosis and intra-lobular parenchymal necrosis. Vascular alterations and secondary ischemia in the pancreas is one of the most important factors involved in the pancreatic lesions present in the WHHL rabbit.     

Is irreversible electroporation safe and effective in the treatment of hepatobiliary and pancreatic cancers?

BackgroundIrreversible electroporation (IRE) is a novel ablative technique for hepatobiliary and pancreatic cancers. This review summarizes the data regarding the safety and efficacy of IRE in the treatment of hepatobiliary and pancreatic cancers.Data sourcesStudies were identified by searching PubMed and Embase for articles published in English from database inception through July 31, 2017. For inclusion, each clinical study had to report morbidity and survival data on hepatobiliary and pancreatic cancers treated with IRE and contain at least 10 patients. Studies that met these criteria were included for analysis. Two authors assessed each clinical study for data extraction. The controversial parts were resolved through discussion with seniors.ResultsA total of 24 clinical studies were included. Fourteen focused on hepatic ablation with IRE comprising 437 patients with 666 lesions of different tumor types. Two patients (0.5%) died after the IRE procedure. Morbidity of hepatic ablation with IRE ranged from 7% to 35%. Most complications were mild. Complete response for hepatic tumors was reported as 57%–97%. Ten studies with 455 patients focused on pancreatic IRE. The overall mortality of IRE in pancreatic cancer was 2%. Overall severe morbidity of IRE in pancreatic cancer ranged from 0 to 20%. The median overall survival after IRE ranged from 7 to 23 months. Patients treated with IRE combined with surgical resection showed a longer overall survival.ConclusionsIRE significantly improves the prognosis of advanced hepatobiliary and pancreatic malignances, and companied with less complications. Hence, IRE is a relatively safe and effective non-thermal ablation strategy and potentially recommended as an option for therapy of patients with hepatobiliary and pancreatic malignances.     

Comorbidities Drive the Majority of Overall Mortality in Low-Risk Mucinous Pancreatic Cysts Under Surveillance

Background & AimsThe Charlson Comorbidity Index (CACI) has been suggested as a tool to determine comorbidity burden and guide management for patients with mucinous pancreatic cysts (Intrapapillary Mucinous Neoplasms and Mucinous Cystic Neoplasms), but has not been studied well among “low-risk” mucinous pancreatic cysts i.e. without worrisome features (WF) and high-risk stigmata (HRS). This study sought to determine the comorbidity burden among surveillance population of low-risk pancreatic cysts and provide their follow-up mortality outcomes.MethodsA single center study retrospectively reviewed a prospective pancreatic cyst database and included individuals with low-risk cysts undergoing serial imaging during 2016. Electronic medical records were reviewed to determine their baseline age-adjusted CACI (age-CACI). After 4 years, their progression to WF, disease specific (pancreatic malignancy-related, DSM), extra-pancreatic (EPM), and overall mortalities (OM) were determined using Kaplan-Meir Survival Analysis.Results502 individuals underwent prospective surveillance. The study included 440 individuals with low-risk suspected or presumed mucinous cysts and excluded 50 and 12 individuals with WF and HRS respectively. Over a median follow-up of 56 months, 12 WF progressions, 2 DSMs, 42 EPMs, and 44 OMs were observed. Baseline age-CACI had good predictive capacity for 4-year EPM (Area-Under Curve: 0.87; p< .0001). The median age-CACI of 4 enabled cohort stratification into Low (age-CACI <4) and High CACI (age-CACI ≥4) groups. A significantly higher OM (p< .001) was observed among the High CACI group as compared to the Low CACI group.ConclusionThrough real-time application of CACI to patient outcomes, our analysis supports incorporation of this comorbidity assessment tool in making shared surveillance decisions among low-risk pancreatic cyst population.     

Pancreatic fate of 6-deoxy-6-[125I]iodo-D-glucose: in vitro experiments

The apparent distribution space of 6-[¹²⁵I]iodi-d-glucose, recently proposed as a tracer of d-glucose transport, was measured in rat isolated islets, acinar tissue, and pieces of pancreas. While such a space reached a steady-state value corresponding to the ³HOH volume in pancreatic islets within 5 min, it slowly increased in pieces of pancreas and, even after 60-min incubation, remained lower than the ³HOH volume. Moreover, the net uptake of 6-deoxy-6-[¹²⁵I]iodo-d-glucose by pancreatic pieces was inhibited by unlabeled 6-deoxy-6-iodo-d-glucose, d-glucose, and cytochalasin B, while being less or not affected by these agents in isolated islets. A preferential labeling of the endocrine, relative to exocrine, moiety of the pancreas was documented both by comparing, after 2 min incubation, the uptake of 6-deoxy-6-[¹²⁵I]iodo-d-glucose by pieces of pancreas from normal vs streptozotocin-injected rats and by comparing the radioactive content of pancreatic islets and acinar tissue obtained from normal rats injected intravenously 3 min before sacrifice with 6-deoxy-6-[¹²⁵I]iodo-d-glucose. It is proposed, therefore, that advantage could conceivably be taken from the vastly different time course for the uptake of selected monosaccharides by pancreatic islets vs acinar cells in the perspective of imaging of the endocrine pancreas by a non invasive method.     

Detection of disseminated pancreatic cells by amplification of cytokeratin-19 with quantitative RT-PCR in blood, bone marrow and peritoneal lavage of pancreatic carcinoma patients

AIM To evaluate the diagnostic potential of cytokeratin-19 (CK-19) mRNA for the detection of disseminated tumor cells in blood, bone marrow and peritoneal lavage in patients with ductal adenocarcinoma of the pancreas.METHODS Sixty-eight patients with pancreatic cancer (n = 37), chronic pancreatitis (n = 16), and non-pancreatic benign surgical diseases (n = 15, control group)were included in the study. Venous blood was taken preoperatively, intraoperatively and at postoperative d 1 and 10. Preoperative bone marrow aspirates and peritoneal lavage taken before mobilization of the tumor were analyzed. All samples were evaluated for disseminated tumor cells by CK-19-specific nested-PCR and quantitative fluorogenic RT-PCR.RESULTS CK-19 mRNA expression was increased in 24 (64%) blood samples and 11 (30%) of the peritoneal lavage samples in the patients with pancreatic cancer.In 15 (40%) of the patients with pancreatic cancer,disseminated tumor cells were detected in venous blood and bone marrow and/or peritoneal lavage. In the peritoneal lavage, the detection rates were correlated with the tumor size and the tumor differentiation. CK-19 levels were increased in pT3/T4 and moderately/poorly differentiated tumors (G2/G3). Pancreatic cancer patients with at least one CK-19 mRNA-positive sample showed a trend towards shorter survival. Pancreatic cancer patients showed significantly increased detection rates of disseminated tumor cells in blood and peritoneal lavage compared to the controls and the patients with chronic pancreatitis.CONCLUSION Disseminated tumor cells can be detected in patients with pancreatic ductal adenocarcinoma by CK-19 fluorogenic RT-PCR. In peritoneal lavage, detection rate is correlated with tumor stage and differentiation. In the clinical use, CK-19 is suitable for the distinction between malignant and benign pancreatic disease in combination with other tumor-specific markers.