Search

This study investigated the influence of mechanical cycling on screwed-in and tappedin implants restored with screw-retained metallic crowns. Three implant-abutmentcrown systems were evaluated: T1 (multi abutment) and T2 (standard abutment) received tapped-in abutments and S received a screwed-in abutment. The specimens were subjected to two million cycles of 0-150 N load, at 2 Hz, 30° inclination in a dry medium, and torque evaluation. Survival and removal torque were analyzed using chisquare, ANOVA, followed by Tukey's test. Differences between installation and removal torque were determined using a T-test for dependent samples. Analyses were performed in SPSS, considering α = 0.05. All specimens survived mechanical cycling in S, 40% in T1, 80% in T2 (p=0.008). Failures occurred due to loosening of the crown screw. A significant decrease in torque (p=0.000) was found. Group T1 had the lowest removal torque (1.6 ± 0.84 N.Cm²), followed by T2 (3 ± 1.49 N.Cm²) and S (6.3 ± 1.16 N. Cm²), and a statistical difference was found between Groups T1 and S. Both types of implantabutment connections were stable and can be considered for rehabilitative treatment, but failure and removal torque were influenced by the design of prosthetic abutment. Crowns were more susceptible to becoming loose in tapped-in systems., (Copyright© 2023 Dennis Barber Ltd.)

Statement of Problem: Although the 2D analysis of prosthesis cementation space has been popular, its correlation with volumetric comparison (3D data) of cement space is unclear., Purpose: The purpose of this in vitro study was to evaluate the cement space in computer-aided design and computer-aided manufacturing (CAD-CAM) crowns of different materials and correlate 2D measurements of cement space with their corresponding 3D values (volume of cement space) by using microcomputed tomography (μCT) analysis of regions of interest., Material and Methods: Ten molar crowns were milled in lithium disilicate (LD), resin nanoceramic (RN), and zirconia (Z) ceramics. Silicone replicas were produced and used as the analog cement layer and scanned with a desktop X-ray microfocus CT scanner. Twenty-eight slices were evaluated in 3 regions: marginal, axial, and occlusal (n=84 measurement points/specimen). After 3D reconstruction of the cement space, the volume was calculated. Data were statistically evaluated through 2-way ANOVA and Bonferroni test (α=.05). The Pearson correlation test was used to investigate the correlation between the 2D and 3D data., Results: The volumes of the occlusal (LD 10 ±1 mm 3 ; RN 9 ±1 mm 3 ) and axial regions (LD 9 ±2 mm 3 ; RN 8 ±1 mm 3 ) were significantly higher than the volume of the marginal region for LD and RN specimens (LD 6 ±2 mm 3 ; RN 4 ±1 mm 3 ) (both P<.001). For the Z group, the axial region had the highest volume (19 ±2 mm 3 ), followed by the volumes of the occlusal (15 ±1 mm 3 ) and marginal regions (12 ±1 mm 3 ). The Pearson correlation test determined a moderate positive correlation of the marginal area (r=0.606, P<.001) and of the axial region (r=0.588, P<.001). However, a moderate negative correlation was found between volume and thickness of the occlusal area (r=-0.437, P=.016)., Conclusions: Z showed more volume of cement space, as well as thicker cement space than LD and RN. The μCT analysis is an efficient method of analyzing cement thickness and volume in ceramic crowns at the selected regions of interest. A moderate positive correlation was found between the 2D and 3D analyses for the axial and marginal regions of ceramic crowns., (Copyright © 2021 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the fatigue survival, fracture loads and failure modes of monolithic lithium disilicate screw-retained crowns, attached to titanium insert, and cement-retained crowns., Materials and Methods: Internal tapered connection implants, embedded in acrylic resin at 30° inclination, were restored with lithium disilicate restorations, simulating a maxillary premolar (n = 20), with different designs: screw-retained titanium base abutment-crowns, and cement-retained crowns. The specimens were submitted to cyclic mechanical loading (1.2 × 10 6 cycles with a load of 0-250 N at 2 Hz). Surviving specimens were subjected to single load to fracture in a universal testing machine and failure modes were determined with the aid of an optical microscope. Maximum load values were analyzed statistically using the t-test and differences in failure modes were analyzed using the chi-squared test (α = 0.05)., Results: All specimens survived the cyclic mechanical loading. Fracture load was significantly higher for screw-retained crowns (821.69 ±196.71 N) than the cement-retained crowns (577.03 ± 137.75 N) (p = 0.005). Ceramic failure was the predominant mode, with no statistical difference between groups., Conclusions: Screw-retained and cement-retained lithium disilicate crowns survived the cyclic mechanical loading. The use of titanium inserts to support a monolithic restoration enhances the fracture strength of the crown/abutment system., (© 2020 by the American College of Prosthodontists.)

Objective:  This survey aimed to assess the effects of coronavirus disease 2019 (COVID-19) on elective and urgency/emergency dental care and dentists concerned., Materials and Methods:  A web-based survey was performed using Google forms questionnaire sent to dentists in Brazil. Questions included: personal information, type of dental care provided during quarantine, if emergencies increased, the dental office biosafety routine, among others. The levels of concern about the impact of quarantine on dental care and patient oral health conditions and the economic impact on dental practices were evaluated using a 0- to 10-point scale. Statistical analysis included descriptive, percentages, one-way ANOVA, Tukey, and chi-square tests., Results:  During quarantine, 64.6% of the dentists attended only urgency/emergency treatments, while 26.1% maintained routine appointments, and 9.3% closed the dental offices. A higher percentage of dentists from the least affected states continued routine dental treatment; dentists were younger and presented a significantly lower level of concern about dental treatments and oral health conditions of their patients. An increase in urgency/emergency procedures was reported by 44.1% of the dentists, mostly due to the unavailability of routine/elective dental care and increased patient anxiety and stress. The main causes of urgency/emergency appointments were toothache, dental trauma, and broken restorations, besides the breakage of orthodontic appliances and temporomandibular disorders. Dentists reported a high level of concern about the economic impact caused by quarantine., Conclusions:  The pandemic/quarantine has negatively affected the clinical routine. Personal protection/hygiene care must be adopted and reinforced by dental professionals/staff to make dental procedures safer., Competing Interests: None declared., (European Journal of Dentistry. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

This survey aimed to assess the concerns of students of health-related higher education in Brazil regarding distance learning during the coronavirus pandemic. A Google Forms anonymous questionnaire was sent by WhatsApp Messenger to students at a private university. Seven hundred and four students answered the questionnaire (566 female, 138 male, mean age = 23.09 years), reflecting approximately a third of the students in health-related disciplines. Students reported feeling anxious due to the pandemic. Most of the students agreed with having the ability to continue education through distance learning, but relatively few of them enjoyed it. Also, students were concerned that learning of clinical material and professional training would be impaired, and they were afraid of failing the year of education. Health-related higher education private institutions in Brazil should focus on reassessing and prioritizing their policies and protocols and include a detailed plan for the future.

Statement of Problem: Identical computer-aided design (CAD) parameters may be used to mill a variety of ceramic materials for computer-aided design and computer-aided manufacture (CAD-CAM) crowns. Whether milled crown spacing matches the designed parameters when more than a single evaluation method is applied is unknown., Purpose: The purpose of this in vitro study was to correlate the stereomicroscope and the microcomputer tomography (μCT) 2-dimensional analysis of the cementation space with the replica technique in assessing 3 different ceramic materials., Material and Methods: The specimens were milled in lithium disilicate, resin nanoceramic, and zirconia (n=30). The cement space was measured at the marginal, axial, and occlusal regions. One hundred twenty measurements of each material were used to correlate the methodologies. Data were statistically evaluated with 2-way repeated measures ANOVA and the Tukey test (α=.05). The Pearson correlation coefficient was used for each region for both methodologies (μCT and optical microscopy) separately., Results: For the μCT analysis, no differences were observed (P>.05) among the materials, but the axial region showed a positive correlation with the marginal (r=0.957) and occlusal regions (r=0.349); the same was observed between the occlusal and marginal regions (r=0.338). However, for stereomicroscope evaluation, resin nanoceramic and zirconia present similar cementation space (P=960), both being different from lithium disilicate (P<.05). The marginal region presented a positive correlation with axial (r=0.149) and occlusal regions (r=0.344), but the axial region showed negative correlation with the occlusal surface (r=-0.205)., Conclusions: The measurements of the scanned replicas were accurate when thinner sections were under measurement. Although the same space parameters were set in the CAD software program, definitive internal dimensions varied among the milled crowns., (Copyright © 2020 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Introduction: Polymer-based composite materials have been proposed as an alternative for single unit restorations, due to their resilient and shock absorbing behavior, in contrast to the brittleness of ceramic materials that could result in failure by fracture., Objective: To evaluate the fatigue strength and damage modes of monolithic posterior resin nanoceramic and lithium disilicate glass ceramic crowns., Methodology: Twenty-six resin nanoceramic (RNC) and lithium disilicate glass ceramic (LD) 2 mm monolithic crowns (n=13) were cemented on composite resin replicas of a prepared tooth and subjected to cyclic load with lithium disilicate indenters for 2 million cycles. Specimens and indenters were inspected every 500,000 cycles and suspended when presenting fractures or debonding. Surviving specimens were embedded in epoxy resin, polished and subsurface damage was analyzed. Specimens presenting fractures or severe subsurface damage were considered as failures. Survival data was subjected to Fisher's exact test; damage modes were subjected to Mann-Whitney test (p<0.05)., Results: There were no debonding, cohesive or catastrophic failures. Considering subsurface damage, 53.8% of RNC and 46.2% of LD crowns survived the fatigue test, presenting no statistical difference. Chief damage modes were radial cracks for RNC and inner cone cracks for LD, presenting no statistical difference., Conclusions: The results suggest that if debonding issues can be resolved, resin nanoceramic figures can be an alternative to posterior crowns. Although distinct, damage modes revealed potential to cause bulk fracture in both glass ceramic and resin nanoceramic crowns.

We present a new method for the rapid analysis of ochratoxin A (OTA) in pig tissues (muscle, liver and kidney) using enzymatic digestion (ED) coupled to high-performance liquid chromatography with a fluorescence detector (HPLC-FLD). OTA was digested with a 1% pancreatin solution in a phosphate buffer and then cleaned with ethylacetate. After being evaporated to dryness and re-dissolved, the sample was determined using HPLC-FLD. The method was validated taking into account the currently permitted limit of 1 μg/kg OTA in pork meat and derived products in Italy. The recovery was higher than 90%. Intra- and inter-day repeatability expressed as RSD were less than 7%. The LOD and LOQ were 0.001 and 0.002 μg/kg, respectively. Our method is more efficient, easier, and cheaper than conventional clean-up procedures (liquid-liquid extraction). •The aim of the study was to develop and validate a quantitative HPLC-FLD method based on ED followed by a chromatographic analysis without any previous clean-up or concentration step for the detection of OTA in pig tissues.•The ED method showed a 90%+ recovery, and intra- and inter-day RSD less than 7%.•This method is simple, rapid, easy to use, and consumes low amounts of organic solvents.

The objective of this study was to investigate the influence of educational materials on the denture hygiene and utilization habits of 70 adult volunteers who had been using complete dentures for at least 5 years. On the day they received new dentures, 32 patients were provided with an illustrated leaflet and verbal instructions on oral hygiene and utilization habits, while the remaining 38 participants were advised to continue cleaning and wearing their new dentures as they had their previous dentures. After a 6- to 10-week period, 66 of 70 subjects were interviewed about socioeconomic factors, denture hygiene, and utilization habits. The percentage of patients with a proper denture care routine was low in both groups, suggesting that patients had a tendency not to change old habits. However, statistical analysis showed a positive correlation between receiving instruction and performing denture care in a way that is closer to the recommended method: brushing without toothpaste, using a specific brush; soaking in a sodium hypochlorite solution; and removing the prosthesis at night. Within the limitations of this study, it was concluded that this approach to patient education could be applied to improve the hygiene and utilization habits of denture wearers as well as encourage the correct use of complete dentures.

Background/aim: A low platelet count is one of the most sensitive tests for cirrhosis detection in patients with hepatitis C virus (HCV) infection. We evaluated whether the human platelet antigen (HPA) genotype could predict platelet count in HCV-positive patients., Materials and Methods: We genotyped the HPA 1, 2, 3, 5 and 15 polymorphisms in consecutive patients with HCV infection., Results: Out of the 56 patients enrolled, 56.1% had liver cirrhosis. The mean platelet count was significantly lower in those with HPA1aa genotype than in those with HPA1ab/bb genotype. Platelet count did not differ among the other HPA polymorphisms. However, at logistic regression analysis, only the HPA3aa genotype and liver cirrhosis were independent predictors of a low platelet count., Conclusion: HPA3aa is an independent factor for a low platelet count in this cohort of patients with HCV chronic infection regardless of disease stage.

The etiopathogenesis of infantile autism is still unknown. Recently some authors have suggested that food peptides might be able to determine toxic effects at the level of the central nervous system by interacting with neurotransmitters. In fact a worsening of neurological symptoms has been reported in autistic patients after the consumption of milk and wheat. The aim of the present study has been to verify the efficacy of a cow's milk free diet (or other foods which gave a positive result after a skin test) in 36 autistic patients. We also looked for immunological signs of food allergy in autistic patients on a free choice diet. We noticed a marked improvement in the behavioural symptoms of patients after a period of 8 weeks on an elimination diet and we found high levels of IgA antigen specific antibodies for casein, lactalbumin and beta-lactoglobulin and IgG and IgM for casein. The levels of these antibodies were significantly higher than those of a control group which consisted of 20 healthy children. Our results lead us to hypothesise a relationship between food allergy and infantile autism as has already been suggested for other disturbances of the central nervous system.