[Association between influenza vaccination and mortality due to COVID-19]. / Asociación entre la vacunación contra influenza y la mortalidad por COVID-19.

Background: It has recently been suggested that influenza vaccination may be a factor associated with decreased COVID-19 mortality. Methods: An age-matched case-control study based on hospital cases. We included subjects aged 18 years and older with a diagnosis of moderate to severe COVID-19. Infection was corroborated by RT-PCR test for SARS-COV-2. Deceased subjects were considered cases, controls were patients discharged due to improvement of acute symptoms. We used bivariate analysis to determine factors associated with death from COVID-19, and calculated odds ratios and 95% confidence intervals. Results: A total of 560 patients were included in the study, 214 (38.2%) were considered cases and 346 (61.7%) controls. A significant difference was observed with the presence of type 2 diabetes mellitus [54% vs. 39.3% between cases and controls, respectively (p=.04)] and having received influenza vaccination (p= .02). Type 2 diabetes mellitus was associated with higher COVID-19 mortality [OR 1.8 (95% CI 1.2-2.5) p=.01], whereas having been immunised against influenza in 2019 was associated with lower mortality in this group of patients [OR .6 (95% CI .4-.9) p=.02]. Conclusions: Influenza vaccination in the previous year appears to be associated with lower mortality from COVID-19; whereas type 2 diabetes mellitus is confirmed as a condition associated with higher mortality.

CBCT uses in clinical endodontics: the effect of CBCT on the ability to locate MB2 canals in maxillary molars.

AIM: To determine whether a CBCT volume can aid in the location of MB2 canals in maxillary molars. METHODOLOGY: This prospective clinical study involved 50 patients that needed RCT on a maxillary molar. The teeth where the MB2 was located upon access with the dental operating microscope received routine root canal treatment, and teeth where MB2 was not located had a CBCT volume made after instrumenting the located canals. At the second appointment, the clinician used the aid of the CBCT volume and troughing to attempt to locate MB2. RESULTS: The clinicians located MB2 upon initial access in 70% (n = 35) of teeth. In the remaining 15 teeth, CBCT and troughing located MB2 53% of the time in that group (8/15 teeth). Overall, MB2 was located in 86% of the 50 first and second maxillary molars (maxillary first molars 90% and maxillary second molars 73%). A total of 15 CBCT volumes were made, and of these teeth, 33% of MB2 canals (5/15 teeth) were visualized on the CBCT volume. CONCLUSIONS: This prospective clinical study showed that the effectiveness of using CBCT to locate additional MB2 canals in maxillary molars appears limited. The use of the dental operating microscope in conjunction with selective troughing and CBCT imaging allowed clinicians to locate 90% (maxillary first molars) and 73% (maxillary second molars) of MB2 canals.

Central α- and ß-thujone: similar anxiogenic-like effects and differential modulation on GABAA receptors in neonatal chicks.

The convulsant effects of α-thujone are attributed to inhibitory actions on the GABAA receptor. We investigated, for the first time, the effects of α-thujone or ß-thujone administrated centrally on the fear/anxiety behaviour of 3-day-old chicks in an Open Field and their modulation on the GABAA receptor. Higher doses were convulsant by eliciting a toxic and excitatory action, with the results showing that a dose of 78 nmol of either of the two diastereoisomers had an anxiogenic-like effect observed as an increased latency to ambulate and a reduced locomotor activity in an Open Field. Nevertheless, only the central administration of α-thujone reversed the increase induced by acute stress in the flunitrazepam-sensitive GABAA receptor recruitment. These findings demonstrated that α-thujone, when intracerebroventricularly administered, suppressed the GABAA receptor recruitment induced by acute stress, maybe due to α-thujone blocking the benzodiazepine binding site or another site of the GABAA complex. However, it should not be discarded that acute stress associated with novelty may have induced the recruitment of a subpopulation of GABAA receptors more sensitive to α-thujone than to the constitutive receptors, or that this monoterpene could have inhibited any protein or enzyme trafficking that modulated the phosphorylation of the receptor involved in the turnover of GABAA receptor. ß-Thujone showed behavioural effects similar to its diastereoisomer α-thujone. However, its action mechanism may have been mediated by other neurotransmitter systems, such as the serotonergic one or by a different biological effectiveness due to a distinct stereochemistry at the specific site of the GABAA receptor.

Effect of the number of basis images on the detection of longitudinal tooth fractures using local computed tomography.

OBJECTIVES: To determine the effect of the number of basis images on the accuracy of local CT (LCT) in detecting longitudinal fractures and test the accuracy of terminal point assessment. METHODS: Longitudinal fractures were induced in 30 of 60 posterior teeth. LCT volumes were generated from 180, 60, 36 and 20 basis images. Ten observers determined the presence of a fracture and its terminal point. Receiver operating characteristic (ROC) analysis was used to quantify detection accuracy, and kappa statistics were used to quantify the concordance between actual and observed terminal point locations. RESULTS: A(z)-values were 0.91, 0.84, 0.74, 0.57 and 0.70 for LCT180, LCT60, LCT36, LCT20 and conventional radiography, respectively (ANOVA: P<0.0001). LCT180 and LCT60 outperformed the other modalities. The respective kappa values for terminal point assessment were 0.52, 0.40, 0.37, 0.16 and 0.32 (ANOVA: P=0.00). LCT180 and LCT60 provided better agreement. CONCLUSIONS: LCT maintained its efficacy for detecting longitudinal fractures with 60 instead of 180 basis images. Agreement between actual and observed terminal point locations was moderate for LCT60 and LCT180.

Relationship between number of proximal contacts and survival of root canal treated teeth.

AIM: The present study tested the hypothesis that having two proximal contacts (PCs) at access is associated with improved survival of root canal treated (RCT) teeth, controlling for important presenting conditions, endodontic variables and restorative factors. METHODOLOGY: A treatment database at the University of Iowa College of Dentistry was used to identify permanent teeth undergoing obturation between 1 July 1985 and 31 December 1987. The list was restricted to teeth of patients with at least one dental visit in each two-year interval from 1985 to 1996, and a simple random sample of 280 patients (n = 400 teeth) was selected. Dental charts, radiographs, and computerized databases were examined to ascertain variables of interest and to verify study inclusion criteria. Kaplan-Meier survival estimates were generated for the 221 teeth satisfying study inclusion criteria. Multivariate Cox models were developed, with standard errors adjusted to account for clustering of teeth within patients. RESULTS: The final Cox model showed that teeth with < or =1 PC at access were lost at a rate three times that of teeth with 2 PCs (hazard ratio = 3.1; 95% confidence interval = 1.9-5.1), controlling for tooth type, presence of radiographic caries at access, and presence of a crown before or after obturation. CONCLUSIONS: Because RCT teeth with two PCs at access experienced substantially better survival than teeth with fewer than two PCs, the influence of PCs on prognosis should be recognized during treatment planning. Future research should employ prospective study designs, capture additional variables, and provide data to support endodontic treatment decisions.

Pain and immunologic response to root canal treatment and subsequent health outcomes.

OBJECTIVE: This study examined the effects of pain and stress associated with a dental procedure, root canal treatment (RCT), on natural killer cell cytotoxicity (NKCC) and the subsequent development of symptoms of upper respiratory illness during the following month. METHODS: Patients (N = 33) were recruited from those scheduled for RCT appointments. Subjects for a non-RCT comparison group (N = 14) were also recruited from dental clinic patients. Peripheral blood was drawn by use of an indwelling catheter three times: just before RCT, 30 minutes after injection of a local anesthetic, and 30 minutes after RCT (a parallel time course was followed for the comparison group.) Blood was assayed for cortisol and NKCC. Subjects completed a health diary in the month after RCT. RESULTS: Patients showed a significant increase in NKCC between baseline and RCT and a significant decrease from RCT to after RCT, whereas the comparison group did not. The NKCC following the RCT was negatively correlated with the pain level during RCT (r = -0.48, p < .01) and pain levels 2 and 6 hours after RCT (r = -0.43, p < .05; r = -0.44 p < .05, respectively). The patient group reported significantly more illness episodes 2 weeks after RCT than the comparison group (Wilcoxon rank sum = 4.78, p = .03). Discriminant function analysis correctly classified 88% of the subjects into the illness category using predictor variables of post-RCT NKCC, stress, and pain levels during RCT (F(3,21) = 8.23, p < .001). CONCLUSIONS: Transitory changes in NKCC associated with pain and stress may be implicated in the development of infectious disease episodes after an acute stressful event.

Microleakage between endodontic temporary restorative materials placed at different times.

Occlusal endodontic access preparations are occasionally made in teeth without removing the original restoration. However, microleakage between restorative materials that are placed at different times has not been extensively studied. Therefore, our objective was to compare microleakage at three areas: between an access opening restorative material and the cavity wall; between an additional material placed later to patch a secondary opening in the first restorative material and the original restorative material itself; and between the secondarily placed material and the cavity wall. Standard endodontic access preparations were made in 120 noncarious, nonrestored crowns of extracted human molars. These teeth were divided into six experimental groups. Another four molars were controls. The endodontic access cavities were restored with either IRM or amalgam as the primary restorative material. After 14 days, half of the primary restorations was removed, and this defect was filled with a secondary restorative material: IRM, Caviton, or a double seal of Caviton and IRM. Microleakage was measured linearly as the extent of basic fuchsin dye penetration under a stereomicroscope after thermal cycling (5 degrees and 55 degrees C for 100 cycles) and tooth sectioning. Wilcoxon signed-rank test was used for statistical analysis. Results indicated significantly less microleakage between primary and secondary restorative materials placed at different times than microleakage between primary temporary restorative materials and the access cavity wall, regardless of the type of primary restorative material used (IRM or amalgam).

Storage-phosphor computed radiography versus film radiography in the detection of pathologic periradicular bone loss in cadavers.

OBJECTIVES: The purpose of this study was to compare D-speed film, E-speed film, and the Soredex Digora system with respect to the detection of periradicular pathosis. STUDY DESIGN: Radiographic images of 100 cadaver jaws were made with E-speed film, D-speed film, and the Soredex Digora. Each set of 100 images was interpreted by four observers, with 30 days separating each of three viewing sessions from the next. The presence or absence of pathologic (inflammatory) periradicular bone resorption was determined by histologic examination of the samples. The observer performance was compared with the true histologic findings and evaluated with receiver operating characteristic and corrected receiver operating characteristic analysis. RESULTS: No statistically significant differences were found in diagnostic performance among the three radiographic techniques. In addition, no imaging technique was a good indicator of pathosis as determined by histologic analysis. CONCLUSION: Under the conditions of this study, it was determined that D-speed film, E-speed film, and the Soredex Digora were equivalent diagnostic imaging modalities with regard to the detection of pathologic periradicular bone resorption. No technique predictably indicated inflammatory resorption.

Considerations for the aesthetic restoration of endodontically treated anterior teeth following intracoronal bleaching.

The major considerations in restoring the pulp chamber following bleaching of endodontically treated anterior teeth include aesthetics, function, appropriate endodontic access preparation, amount of remaining tooth structure, type of restorative material, prevention of microleakage, and prevention of iatrogenic perforation. The learning objective of this article is to review the considerations that must be made when placing aesthetic restorations in the pulp chamber and access opening of endodontically treated teeth following intracoronal bleaching. The advantages and disadvantages of the proposed techniques and materials are discussed, as are the methods for avoiding excessive removal of the tooth structure. Two case reports are used to demonstrate the clinical procedures. The authors suggest placing white gutta-percha stopping material in the pulp chamber and a composite restoration in the access opening following root canal treatment and/or bleaching procedures in the anterior dentition.

Canal debridement: effectiveness of sodium hypochlorite and calcium hydroxide as medicaments.

The action of chemicals such as calcium hydroxide (Ca(OH)2) and sodium hypochlorite (NaOCl) that are used as tissue solvents may be enhanced by prolonged contact. The objective of this study was to determine if sealing Ca(OH)2 and NaOCl into the canal space would improve debridement of both the main canal and areas inaccessible to files. Mesial root canals of 75 freshly extracted mandibular molars were step-back hand-instrumented. Another six molars were controls. Either Ca(OH)2, NaOCl, or no medication was sealed in the canals for 1 or 7 days. Canals were finally irrigated with H2O and prepared for histological evaluation. The cleanliness of main canals and inaccessible areas (isthmi and fins) at the apical, middle, and coronal thirds was examined, scored, and compared by nonparametric statistical analysis. Results showed no significant differences among different groups in either the 1-day or 7-day time intervals in either the main canal or inaccessible areas. Instrumentation combined with NaOCl irrigation alone accounted for the removal of tissue in the main canal. In conclusion, in this system, prolonged contact with Ca(OH)2 and NaOCl was similarly ineffective; neither contributed significantly to canal debridement.

Penicillin as a supplement in resolving the localized acute apical abscess.

PROBLEM: Antibiotics are often prescribed indiscriminately to treat endodontic emergencies. OBJECTIVES: This study examined (1) the effect of penicillin supplementation on reduction of symptoms and (2) the course of recovery of localized acute apical abscess after emergency treatment. STUDY DESIGN: Patients with pulp necrosis and periapical pain and/or localized swelling were considered. Those eligible did not have any signs of spreading infections. Patients received appropriate local treatment, and a double-blind protocol was used to randomly assign them to one of three groups: penicillin VK group, placebo group, or neither medication group. All received ibuprofen 600 mg four times daily for 24 hours. Patients entered their pre- and postoperative pain and swelling experience on a visual analog scale for up to 72 hours. RESULTS: Resolution was fairly rapid in most patients. Statistical analysis of the scores of 32 respondents revealed no significant differences (at p < 0.05) between the three groups in course of recovery or symptoms at any time period. CONCLUSIONS: Patients with localized periapical pain or swelling generally recovered quickly with local treatment. The data did not show a demonstrable benefit from penicillin supplementation.

Immunoexpression of epidermal growth factor in odontogenesis of the offspring of alcoholic mice.

Several forms of cell perturbation have been associated with ethanol ingestion. Fetal alcohol syndrome (FAS) as well as diminished maxillofacial development and inhibition of cell regeneration in vitro and in vivo have been described. Epidermal growth factor (EGF) stimulates maxillofacial growth, DNA synthesis, and it is a potent mitogen for a number of various cell types. EGF exerts its effects on cells through binding to a specific cell surface receptor which leads to activation of a thyrosine kinase in the intracellular part of the receptor. The inhibitory effect of alcohol on EGF in the mouse dental follicle was studied in the offspring of alcoholic mothers using immunocytochemistry. Adult female mice were given 22% alcohol in their drinking water and fed a pelleted diet before and during pregnancy. Maternal blood alcohol levels were 262 +/- 1.3 mg/100 ml on gestation day 12.5. The offspring of the alcoholic and control mice were sacrificed on postnatal day 1.5, their mandibles were dissected, weighed and processed by routine immunocytochemistry with the following results. 1) Significant differences were found in mandible weight p < 0.01 after parturition. 2) The tooth germs in the offspring of ethanol treated mice were morphometrically smaller than those of control littermates. 3) Immunoexpression of EGF in the mandibular first molar of the control group was strong and homogeneous while in the experimental group the expression was light and heterogeneous. It is concluded that maternal alcoholism reduces EGF in the offspring.

Anaerobic tissue-dissolving abilities of calcium hydroxide and sodium hypochlorite.

Closed root canals likely have an oxygen-free environment; most bacteria in canals are anaerobic. These bacteria and other debris are difficult to remove. Unknown is tissue dissolution with chemicals under these anaerobic conditions. This study evaluated and compared dissolving properties of calcium hydroxide (Ca(OH)2) and sodium hypochlorite (NaOCl) on bovine pulp tissue in aerobic and anaerobic environments. Sixty bovine pulp specimens were dried, then randomly divided into six groups. Groups A and B were immersed in Ca(OH)2 + water solution, whereas group C and D were in 2.5% NaOCl. Groups E and F (controls) specimens were placed in distilled water. Groups A, C, and E were incubated anaerobically, and groups B, D, and F were incubated under regular atmospheric conditions, all for 7 days. Percentages of weight loss were compared between groups. Results showed the following: (a) both chemicals partially dissolved pulp tissue, (b) anaerobic environment did not alter tissue-dissolving properties of Ca(OH)2 or NaOCl, and (c) Ca(OH)2 and NaOCl were equal and more effective than water.

Spermine increases paired-pulse facilitation in area CA1 of hippocampus in a calcium-dependent manner.

The effect of spermine on neurotransmission was studied in area CA1 of the hippocampal slice preparation. Paired-pulse stimulation (20 ms interpulse interval) was delivered to stratum radiatum; the evoked field potential responses were recorded simultaneously from stratum radiatum and from stratum pyramidale. At mM and sub-mM concentrations, spermine decreased the slope of pEPSP in stratum radiatum and the area of the conditioning population spike in stratum pyramidale. Short-latency paired-pulse inhibition of the population spike was converted to facilitation by spermine. These effects of spermine resembled those observed at low calcium concentration. In addition, dose-response and input-output curves determined at various Ca2+ concentrations demonstrated that the depressant effects of spermine were larger at low Ca2+ levels. The results support the notion that spermine competitively blocks presynaptic voltage-sensitive Ca2+ channels, thus causing a decreased release of neurotransmitter. Since spermine is present in brain, it is likely that it is a natural modulator of Ca2+ channels.

A three-dimensional finite-element stress analysis of an endodontically prepared maxillary central incisor.

This study is an application of a three-dimensional Finite-Element Method to investigate the changes in stress characteristics of a prepared maxillary central incisor. The purpose of this study was to analyze stress distributions in this tooth after simulated canal preparation and static loading. A maxillary central incisor was embedded in acrylic, sectioned, photographed, and digitized. A three-dimensional finite-element model was generated by a computer and appropriately modified to simulate canal preparation. Data identified the highest stress magnitudes to be located between the middle and coronal thirds of the root; an area clinically observed to be prone to fracture during treatment. In addition, the magnitude of generated stresses was directly correlated with the simulated prepared canal diameter. The development of a validated three-dimensional finite-element method could identify areas that may predispose a tooth to structural failure during condensation loads.

Vertical root fracture in nonendodontically treated teeth.

Vertical root fractures have been reported to occur primarily in endodontically treated teeth due to condensation forces and/or with post placement. This study describes 11 Chinese patients with 12 molars that developed vertical root fractures without endodontic or post procedures. These showed characteristics of a true vertical root fracture as confirmed after extraction. Fractured teeth showed a consistent pattern. The majority were severely attrited mandibular molars in males. All had clinically intact crowns with no or minimal restorations.

Extensive idiopathic apical root resorption. A case report.

Multiple idiopathic external apical root resorption is an unusual phenomenon. A brief review of cases in the literature is presented as well as a report of a patient with severe resorption. No significant systemic, dental, or familial findings could be identified as a possible cause. Careful chronologic radiographic documentation showed that roots with normal length began to resorb several years earlier, and the resorption continued over a defined period of time, terminating spontaneously before tooth loss or obvious pulp damage. Because the pathogenesis is generally unknown, no specific treatment modalities exist at present.

Placement of calcium hydroxide in simulated canals: comparison of glycerin versus water.

Calcium hydroxide (Ca(OH)2) is an intracanal medicament used as an antimicrobial agent, temporary obturant, and for apexification. Placement should be controlled for the maximum biological effect. This study evaluated and compared the effectiveness of delivery of Ca(OH)2 mixed with water or with glycerin as to (a) length of placement and (b) density of fill at different levels. Fifty-six simulated canals with moderate curvature were prepared to #60 using the step-back technique. Ca(OH)2 was mixed with either water (28 canals) or glycerin (28 canals) into a thick paste and placed with lentulo spirals. Radiographs were made and blindly assessed. Results showed that glycerin was statistically significantly superior (p < 0.05) to water as to (a) length of fill and (b) density in the coronal, middle, and apical thirds. Of particular interest was the apical third, in which 0% of water and 50% of glycerin Ca(OH)2 pastes were completely dense.

Placement accuracy of electrically conductive gutta-percha.

Conductive gutta-percha master cones (CGPMCs) with a surface conductive silver film have been developed for use with an electronic apex locator. Our research examined the accuracy of these CGPMC placed at working length (WL). Actual canal lengths of 30 extracted anterior teeth with mature apices were determined. Teeth were mounted in an in vitro system and canals step-back prepared. Each CGPMC was seated to the electronic WL as determined by the electronic apex locator and radiographs were made with the CGPMC in this position. Data showed (a) CGPMCs placed with the use of an electronic apex locator were at or within 1 mm short of WL in 36% of the teeth and (b) however, radiographic examination of the same CGPMC placements gave the appearance that 64% were at or within 1 mm short of WL.