Dentinal Damage and Fracture Resistance of Oval Roots Prepared with Single-file Systems Using Different Kinematics

Introduction

Vertical root fracture is a common finding in endodontically treated teeth, notably oval roots. The aim of the present study was to determine the effect of instrumentation kinematics and the material of instrument construction of single-file systems on dentin walls and fracture resistance of oval roots.

Methods

Sixty-five roots with oval canals were allocated into a control group (n = 5) and 3 experimental groups of 20 roots each. Group WO was instrumented with the WaveOne primary file (Dentsply Maillefer, Baillagues, Switzerland), group PT-Rec was prepared with F2 ProTaper files (Dentsply Maillefer, Baillagues, Switzerland) used in a reciprocating motion, and group PT-Rot was prepared with F2 ProTaper files used in a rotation motion. For crack evaluation, half of the samples (n = 30) were embedded in acrylic resin, and the blocks were sectioned at 3, 6, and 9 mm from the apex. The sections were examined under a stereomicroscope and scored for crack presence. The other half of the specimens (n = 30) were obturated using lateral condensation of gutta-percha and AdSeal sealer (Meta Biomed Co, Ltd, Chungbuk, Korea). The specimens were then subjected to a load of 1 mm/min to determine the force required to fracture the roots.

Results

WaveOne instruments induced the least amount of cracks and exhibited greatest resistance to fracture compared with ProTaper F2 files whether used in reciprocating or rotating motions.

Conclusions

The alloy from which the material is manufactured is a more important factor determining the dentin damaging potential of single-file instruments than the motion of instrumentation.     

Experimental Investigation on the Structural Performance of Single Span Hollow Core Slab under Successive Impact Loading

In Lebanon and many other countries where structures are vulnerable to impact loads caused by accidental rock falls due to landslides, specifically bridges with hollow core slab, it is mandatory to develop safe and efficient design procedures to design such types of structures to withstand extreme cases of loading. The structural response of concrete members subjected to low velocity high falling weight raised the interest of researchers in the previous years. The effect of impact due to landslide falling rocks on reinforced concrete (RC) slabs has been investigated by many researchers, while very few studied the effect of impact loading on pre-stressed structures, noting that a recent study was conducted at Beirut Arab University which compared the dynamic behavior of reinforced concrete and post-tensioned slabs under impact loading from a 605 kg impactor freely dropped from a height of 20 m. Hollow core slabs are widely used in bridges and precast structures. Thus, studying their behavior due to such hazards becomes inevitable. This study focuses on these types of slabs. For a better understanding of the behavior, a full scale experimental program consists of testing a single span hollow core slab. The specimen has 6000 mm × 1200 mm × 200 mm dimensions with a 100 mm cast in a place topping slab. Successive free fall drops cases from 14 m height will be investigated on the prescribed slab having a span of 6000 m. This series of impacts will be held by hitting the single span hollow core slab at three different locations: center, edge, and near the support. The data from the testing program were used to assess the structural response in terms of experimental observations, maximum impact and inertia forces, structural damage/failure: type and pattern, acceleration response, and structural design recommendations. This research showed that the hollow core slab has a different dynamic behavior compared to the post tensioned and reinforced concrete slabs mentioned in the literature review section.     

Development of remineralizing, antibacterial dental materials

Light curable methacrylate dental monomers containing reactive calcium phosphate filler (monocalcium phosphate monohydrate (MCPM) with particle diameter of 29 or 90 μm) and β-tricalcium phosphate (β-TCP) at 1:1 weight ratio in a powder:liquid ratio (PLR) of 1:1 or 3:1 and chlorhexidine diacetate (0 or 5 wt.%), were investigated. Upon light exposure, approximately 90% monomer conversion was gained irrespective of the formulation. Increasing the PLR promoted water sorption by the set material, induced expansion and enhanced calcium, phosphate and chlorhexidine release. Concomitantly, a decline in compressive and biaxial flexural strengths occurred. With a reduction in MCPM particle diameter, however, calcium and phosphate release was reduced and less deterioration in strength observed. After 24 h, the remaining MCPM had reacted with water and β-TCP, forming, within the set materials, brushite of lower solubility. This provided a novel means to control water sorption, component release and strength properties. Measurable chlorhexidine release was observed for 6 weeks. Both diffusion rate and total percentage of chlorhexidine release decreased with lowering PLR or by adding buffer to the storage solutions. Higher chlorhexidine release was associated with reduced bacterial growth on agar plates and in a biofilm fermenter. In cell growth media, brushite and hydroxyapatite crystals precipitated on the composite material surfaces. Cells spread on both these crystals and the exposed polymer composite surfaces, indicating their cell compatibility. These formulations could be suitable antibacterial, biocompatible and remineralizing dental adhesives/liners.     

Effects of pre-emptive analgesia on efficacy of buccal infiltration during pulpotomy of mandibular primary molars: a double-blinded randomized controlled trial

Objective: To assess the effect of preoperative administration of ibuprofen and acetaminophen on the efficacy of buccal infiltration for pulp therapy in mandibular primary molars.

Materials and methods: A randomized controlled trial with an ID no. NCT03423329 in Clinical-Trials.gov was conducted in the outpatient clinic of Paediatric Dentistry Department at Ain Shams University. The study was designed with two test arms where either ibuprofen or acetaminophen was administered to children whereas in the control arm a multivitamin placebo was used. Children's self-reported pain responses were recorded using Wong–Baker FACES pain scale. For statistical analysis, Chi-square test or Fisher’s exact test was used to compare between the three groups whereas Friedman’s test was used to study changes within each group.

Results: In a sample of 60 children, a significant decrease in the mean pain rating scores was detected in all groups where success rates ranged from 40% with ibuprofen to 55% and 65% with acetaminophen and placebo, respectively. However, there was no statistically significant difference between the three groups regarding severity of pain during access cavity preparation.

Conclusions: Both analgesics have no clinical advantage over the placebo in increasing the efficacy of buccal infiltration during pulp therapy in mandibular primary molars.     

Sepsis in end-stage renal disease patients: are they at an increased risk of mortality?

ObjectivesThis study aims to examine the outcome of end-stage renal disease (ESRD) patients admitted with sepsis to the intensive care unit (ICU).DesignSingle centre, retrospective cohort studySettingThe study was conducted in the Intensive Care Department of King Abdulaziz Medical City, Riyadh, Saudi Arabia.ParticipantsData were extracted from a prospectively collected ICU database from 2002 to 2017. Patients were considered to have sepsis based on the sepsis-3 definition and were stratified into 2 groups based on the presence or absence of ESRD.Primary and secondary outcomesThe primary outcome of the study was in-hospital mortality. Secondary outcomes included ICU mortality, ICU and hospital lengths of stay, and mechanical ventilation duration.ResultsA total of 8803 patients were admitted to the ICU with sepsis during the study period. 730 (8.3%) patients had ESRD. 49.04% of ESRD patients with sepsis died within their hospital stay vs. 31.78% of non-ESRD patients. ESRD septic patients had 1.44 greater odds of dying within their hospital stay as compared to septic non-ESRD patients (OR 1.44, 95% CI 1.03–1.53). Finally, the predictors of hospital mortality in septic ESRD patients were found to be mechanical ventilation (OR 3.36; 95% CI 2.27–5.00), a history of chronic liver disease (OR 2.26; 95% CI 1.26–4.07), and use of vasopressors (OR 1.74; 95% CI 1.19–2.54). Among patients with ESRD, hospital mortality was higher in subgroups of patients with chronic cardiac (OR 1.86 (1.36–2.53) vs. 1.19 (0.96–1.47)) and chronic respiratory illnesses (OR 2.20 (1.52–3.20) vs. 1.21 (0.99–1.48)).ConclusionESRD patients admitted to the intensive care unit with sepsis are at greater odds of mortality compared to patients with non-ESRD. This risk is particularly increased if these patients have a concomitant history of chronic cardiac and respiratory illnesses.

Key Messages

• Sepsis and bacterial infections are very common in ESRD patients and following cardiovascular disease; sepsis is the second leading cause of death in patients with ESRD.
• This study aims to examine the outcome of patients with end-stage renal disease (ESRD) patients admitted with sepsis to the intensive care unit (ICU).
• The results of this study have shown that end-stage renal disease is associated with greater odds of ICU and hospital mortality among septic patients admitted to an intensive care unit.
• ESRD patients were also more likely to be started on vasopressors and mechanical ventilation.