Fracture resistance and 2-body wear of 3-dimensional–printed occlusal devices

Statement of problem

Polymeric material for 3-dimensional printing can be used to fabricate occlusal devices. However, information about fracture resistance and wear is scarce.

Bone Mass,Bone Microstructure and Biomechanics in Patients with Hand Osteoarthritis

The impact of primary hand osteoarthritis (HOA) on bone mass, microstructure, and biomechanics in the affected skeletal regions is largely unknown. HOA patients and healthy controls (HCs) underwent high-resolution peripheral quantitative computed tomography (HR-pQCT). We measured total, trabecular, and cortical volumetric bone mineral densities (vBMDs), microstructural attributes, and performed micro–finite element analysis for bone strength. Failure load and scaled multivariate outcome matrices from distal radius and second metacarpal (MCP2) head measurements were analyzed using multiple linear regression adjusting for age, sex, and functional status and reported as adjusted Z-score differences for total and direct effects. A total of 105 subjects were included (76 HC: 46 women, 30 men; 29 HOA: 23 women, six men). After adjustment, HOA was associated with significant changes in the multivariate outcome matrix from the MCP2 head (p < .001) (explained by an increase in cortical vBMD (Δz = 1.07, p = .02) and reduction in the trabecular vBMD (Δz = −0.07, p = .09). Distal radius analysis did not show an overall effect of HOA; however, there was a gender-study group interaction (p = .044) explained by reduced trabecular vBMD in males (Δz = −1.23, p = .02). HOA was associated with lower failure load (−514 N; 95%CI, −1018 to −9; p = 0.05) apparent in males after adjustment for functional status. HOA is associated with reduced trabecular and increased cortical vBMD in the MCP2 head and a reduction in radial trabecular vBMD and bone strength in males. Further investigations of gender-specific changes of bone architecture in HOA are warranted. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.     

Fracture behavior of structurally compromised non-vital maxillary premolars restored using experimental fiber reinforced composite crowns

PURPOSE: To study the fracture behavior of direct resin composite crowns with or without experimental fiber reinforcement. METHODS: Clinical crowns of single-rooted maxillary premolars were cut off at the cemento-enamel junction. Canals were prepared with Gates Glidden drills up to size 4. No additional post-space preparations were made. Roots were embedded in acrylic and canal entrances were standardized (depth 2 mm, diameter 1.75 mm). Three groups of 14 samples were treated as follows: (1) custom-made glass FRC post (EverStick Post); fibers 5 mm deep in the canal, (2) similar post-system as (1) with incorporation of a new type of glass fiber fabric, (3) no fiber reinforcement (control). Posts were cemented with resin cement (Panavia F). Resin composite crowns (Filtek Z250) were made using an anatomically formed mold. Static load until fracture was applied using a universal loading device with a cylindrical bar (diameter 2 mm) with a crosshead speed of 5 mm/minute (loading angle: 30 degrees to the tooth long-axis). Failure modes were categorized as favorable and unfavorable failures. RESULTS: There was no significant difference in mean failure loads among the four groups (P > 0.05). Favorable failures occurred significantly more often in Group 2 than in the other groups (P < 0.05). The results suggest that an incorporated glass fiber fabric does not affect the load-bearing capacity of resin composite complete crowns on structurally compromised and non-vital premolars. Incorporation of a glass fiber fabric, however, has a beneficial effect on the failure mode.     

Incidence and risk factors for injuries to the recurrent laryngeal nerve during neck surgery in the moderate-volume setting

Purpose

Total lobectomy is currently recommended also in benign thyroid disease in order to reduce the risk of goitre recurrence, an approach claimed not to increase post-operative morbidity. The aim of the study was to analyse risk factors for recurrent laryngeal nerve (RLN) palsy during neck surgery, with particular interest in complications after total lobectomy and subtotal resection, respectively.

Methods

All consecutive patients operated for thyroid and parathyroid diseases at one institution between 1984 and 2011 were prospectively recorded, and 1,322 patients were included. Patients with permanent post-operative RLN palsy were re-examined in 2011.

Results

The risk of permanent RLN palsy after parathyroid surgery was 0.3 %. Patients operated for thyroid cancer had a 5.9 % risk of permanent nerve injury, higher than that of patients with benign thyroid disease (1.4 %; P?=?0.029). Independent risk factors for RLN paralysis after benign thyroid surgery were intrathoracic goitre (odds ratio (OR), 3.57; 95 % confidence interval, 1.70–7.48), ipsilateral redo-surgery (OR, 3.64; 1.00–13.28) and total lobectomy (OR, 2.41; 1.05–5.55). At long-time follow-up (median, 10 years), 7 of 12 patients with permanent RLN palsy still suffered moderate or severe symptoms.

Conclusions

RLN paralysis is an infrequent complication after neck surgery, but with major negative impact on patients’ well-being when permanent. Hemithyroidectomy/total thyroidectomy is increasingly preferred over subtotal resection in multinodular goitre. This is supported by an increased risk of RLN injury during redo-surgery for recurrency but should be carefully weighed against individual risk factors for nerve palsy, including surgical experience and volume.     

Sensitivity of serum concentration of cartilage biomarkers to 21‐days of bed rest

The objective of the study was to test the hypothesis that serum levels of cartilage oligomeric matrix protein (COMP) would decrease and serum levels of tumor‐necrosis factor alpha (TNF‐α) and selected matrix metalloproteinases (MMPs) would increase in response to bed rest (BR) and that these changes are unaffected by the intake of potassium bicarbonate or whey protein. Seven and nine healthy male subjects participated in two 21‐day 6° head down tilt crossover BR‐studies with nutrition interventions. Serum samples were taken before, during, and after BR and biomarker concentrations were measured using commercial enzyme‐linked immunosorbent assays. MMP‐3 during BR was significantly lower than at baseline (reduction greater 20%; p < 0.001). MMP‐3 increased significantly from 14 to 21 days of BR (+7%; p = 0.049). COMP during BR was significantly lower than at baseline (reduction greater 20%; p < 0.001). MMP‐3 and COMP returned to baseline within 1 day after BR. MMP‐9 on day 3 of BR was significantly lower than at baseline (?31%; p < 0.033) and on days 3, 5, and 14 of BR significantly lower than at the end of and after BR (reduction greater 35%; p < 0.030). The nutritional countermeasures did not affect these results. The observed changes in cartilage biomarkers may be caused by altered cartilage metabolism in response to the lack of mechanical stimulus during BR and inflammatory biomarkers may play a role in changes in biomarker levels. Clinical relevance: Immobilization independently from injury can cause altered cartilage biomarker concentration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1465–1471, 2018.

     

Large variation in ESBL-producing <Emphasis Type="Italic">Escherichia coli</Emphasis> carriers in six European countries including Russia

We investigated the faecal carriage prevalence of extended-spectrum β-lactamase production in Escherichia coli (EP-EC) and/or Klebsiella pneumoniae (EP-KP) and risk factors associated with carriage among adult study subjects in Finland, Germany, Latvia, Poland, Russia and Sweden (partner countries). The aim was to get indicative data on the prevalence of ESBL-carriage in specific populations in the region. Faecal samples were collected from four study populations and screened on ChromID-ESBL and ChromID-OXA-48 plates. Positive isolates were further characterised phenotypically. Our results show a large variation in carrier prevalence ranging from 1.6% in Latvia to 23.2% in Russia for EP-EC. For the other partner countries, the prevalence of EP-EC were in increasing numbers, 2.3% for Germany, 4.7% for Finland, 6.6% for Sweden, 8.0% for Poland and 8.1% for all partner countries in total. Carriers of EP-KP were identified only in Finland, Russia and Sweden, and the prevalence was <?2% in each of these countries. No carriers of carbapenemase-producing isolates were identified. This is the first study reporting prevalence of carriers (excluding traveller studies) for Finland, Latvia, Poland and Russia. It contributes with important information regarding the prevalence of EP-EC and EP-KP carriage in regions where studies on carriers are limited.     

Collection of peripheral blood progenitor cells for autologous use: performance enhancements of COBE spectra, auto-PBSC

Collection of peripheral blood stem cells (PBSC) must be performed in a safe and effective manner. Issues like automation, collection efficiency (CE), and adverse events must be considered. Auto-PBSC (COBE Spectra) is a fully automated program for PBSC collection. Changes in the protocol were made to achieve high CE, low product volume, and resulted in three groups of patients. Standard operating procedures (SOPs) were developed to reduce citrate toxicity and patients with central venous catheter. Twenty patients and 27 collections (Group 1), 88 patients and 112 collections (Group 2), and 158 patients and 194 collections (Group 3) were recorded. The protocol changes increased CE significantly from 31% (Group 1) to 57 and 59% (Group 2 and 3). Adjusting endpoint according to the preapheresis number of CD34+ cells reduced the collection time and the volume of the product significantly (median 227 min and 56 mL) without affecting CE. Mean level of ionized calcium before collection was 1.22 mmol/L, measured in 31 patients. This declined to a mean of 1.07 mmol/L after 1 h of collection and remained unchanged despite continuous calcium infusion. The number of patients with mild symptoms of citrate toxicity was reduced from 20 to 6%. A central venous catheter was used in 15%. Compared to peripheral access no differences in blood flow rate or time to perform the collection were found. Changes in the Auto-PBSC protocol resulted in an improved CE and a small product. SOPs reduced the number of patients with citrate toxicity and with central venous catheter.