Short-term and long-term impacts of COVID-19 on economic vulnerability: a population-based longitudinal study (COVIDENCE UK).

OBJECTIVE: To determine whether COVID-19 has a significant impact on adequacy of household income to meet basic needs (primary outcome) and work absence due to sickness (secondary outcome), both at the onset of illness (short term) and subsequently (long term). DESIGN: Multilevel mixed regression analysis of self-reported data from monthly online questionnaires, completed 1 May 2020 to 28 October 2021, adjusting for baseline characteristics including age, sex, socioeconomic status and self-rated health. SETTING AND PARTICIPANTS: Participants (n=16 910) were UK residents aged 16 years or over participating in a national longitudinal study of COVID-19 (COVIDENCE UK). RESULTS: Incident COVID-19 was independently associated with increased odds of participants reporting household income as being inadequate to meet their basic needs in the short term (adjusted OR (aOR) 1.39, 95% CI 1.12 to 1.73) though this did not persist in the long term (aOR 1.00, 95% CI 0.86 to 1.16). Exploratory analysis revealed a stronger short-term association among those who reported long COVID, defined as the presence of symptoms lasting more than 4 weeks after disease onset, than those reporting COVID-19 without long COVID (p for trend 0.002). Incident COVID-19 associated with increased odds of reporting sickness absence from work in the long term (aOR 4.73, 95% CI 2.47 to 9.06) but not in the short term (aOR 1.34, 95% CI 0.52 to 3.49). CONCLUSIONS: We demonstrate an independent association between COVID-19 and increased risk of economic vulnerability among COVIDENCE participants, measured by both household income sufficiency and sickness absence from work. Taking these findings together with pre-existing research showing that socioeconomic disadvantage increases the risk of developing COVID-19, this may suggest a 'vicious cycle' of impaired health and poor economic outcomes. TRIAL REGISTRATION NUMBER: NCT04330599.

Root canal preparation in mandibular premolars with TRUShape and Vortex Blue: A micro-computed tomography study.

A comparison of the preparation ability of two root canal instrumentation systems in oval-shaped canals using micro-computed tomography was undertaken. Thirty extracted, single-rooted, human mandibular premolars with radiographically similar canal morphology were selected, allocated to two groups (N = 15) and prepared with TRUShape or Vortex Blue (VB). Each sample was subjected to three scans (20 µm resolution): pre-preparation and after preparation to sizes #30 and #40. Three-dimensional data sets were evaluated for canal volume, surface area and surface treatment. Matched axial slices in apical, middle and coronal root thirds were evaluated for cross-sectional area, roundness and transportation. Preparation with both instruments increased canal volumes and surface areas similarly and significantly (P < 0.001) with no significant difference between groups. TRUShape significantly enhanced surface treatment at both apical sizes (P < 0.05). Transportation exceeded 100 µm in only eight out of 90 cross sections. Both instruments performed similarly during preparation. TRUShape, however, significantly enhanced surface treatment.

Comparison of Mechanical and Indirect Ultrasonic Placement Technique on Mineral Trioxide Aggregate Retrofill Density in Simulated Root-end Surgery.

INTRODUCTION: The objective of this study was to evaluate the density of mineral trioxide aggregate (MTA) root-end filling placed by either manual condensation or manual condensation with indirect ultrasonic activation under simulated root-end surgery conditions in vitro. METHODS: Extracted human molar teeth were obtained and sectioned to provide single-rooted samples (n = 50). Roots were instrumented to a size of 40 with a .04 taper and obturated with a warm vertical technique. The coronal end of each root was embedded in resin. A root-end resection and root-end preparation were completed on each root. Samples were randomly assigned to receive root-end fillings with ProRoot MTA (Dentsply, Tulsa, OK) by 1 of 2 techniques: manual condensation alone (group M, n = 25) or manual condensation with indirect ultrasonic activation (group U, n = 25). MTA was placed incrementally to the level of the root end using the enumerated technique. Samples were weighed immediately before and after filling placement. MTA was removed from all samples so as not to change the root-end preparation, rinsed, and dried. Each sample then underwent MTA placement by the opposite technique, and weight was again measured immediately before and after MTA placement. MTA filling weights for each technique were analyzed statistically using a technique for repeated measures analysis. Statistical analysis was conducted to account for any carryover or order effects. RESULTS: After adjustment for carryover effects, it was found that regardless of the order of placement, the mean fill weight of MTA produced by the indirect ultrasonic method was on average 4.42 mg heavier than that produced by manual condensation alone. This result was statistically significant (P < .0003). CONCLUSIONS: Under simulated root-end surgery conditions, indirect ultrasonic condensation of MTA root-end fillings was shown to produce a filling that was significantly denser than MTA placed by manual condensation alone.

Massive Open Online Courses in Dental Education: Two Viewpoints: Viewpoint 1: Massive Open Online Courses Offer Transformative Technology for Dental Education and Viewpoint 2: Massive Open Online Courses Are Not Ready for Primetime.

This point/counterpoint article discusses the strengths and weaknesses of incorporating Massive Open Online Courses (MOOCs) into dental education, focusing on whether this relatively new educational modality could impact traditional dental curricula. Viewpoint 1 asserts that MOOCs can be useful in dental education because they offer an opportunity for students to learn through content and assessment that is delivered online. While specific research on MOOCs is limited, some evidence shows that online courses may produce similar learning outcomes to those in face-to-face courses. Given that MOOCs are intended to be open source, there could be opportunities for dental schools with faculty shortages and financial constraints to incorporate these courses into their curricula. In addition to saving money, dental schools could use MOOCs as revenue sources in areas such as continuing education. Viewpoint 2 argues that the hype over MOOCs is subsiding due in part to weaker than expected evidence about their value. Because direct contact between students, instructors, and patients is essential to the dental curriculum, MOOCs have yet to demonstrate their usefulness in replacing more than a subset of didactic courses. Additionally, learning professionalism, a key component of health professions education, is best supported by mentorship that provides significant interpersonal interaction. In spite of the potential of early MOOC ideology, MOOCs in their current form require either further development or altered expectations to significantly impact dental education.

Time required to remove guttacore, thermafil plus, and thermoplasticized gutta-percha from moderately curved root canals with protaper files.

INTRODUCTION: A novel carrier-based obturation system, GuttaCore, was developed to facilitate more efficient nonsurgical retreatments. This ex vivo study evaluated the time required for re-treating GuttaCore and 2 other common obturation materials in moderately curved canals with ProTaper retreatment and ProTaper files. METHODS: Sixty mesial roots of mandibular molars with the same mean curvature were randomly divided into 3 experimental groups: warm vertical, Thermafil Plus, and GuttaCore. Ten teeth served as positive and negative controls. The mesiobuccal canal in each sample was prepared to ISO size 30 with 0.04 taper. The warm vertical group was obturated by using a continuous-wave technique of gutta-percha compaction, and the Thermafil Plus and GuttaCore groups were obturated according to manufacturers' instructions. After allowing sealer to set, each specimen was sequentially treated with ProTaper Retreatment files D1, D2, and D3 and ProTaper Universal file F3 to the predetermined working length. The time taken to reach working length (T1) and the time required for obturation material removal (T2) were recorded. RESULTS: One-way analysis of variance followed by post hoc Tukey-Kramer test indicated that the mean total time to remove filling material for the GuttaCore group was significantly shorter than those observed in the other groups (P < .05). No significant difference was observed between warm vertical and Thermafil Plus groups. CONCLUSIONS: GuttaCore is removed in less time from moderately curved canals with ProTaper files than either thermoplasticized gutta-percha or Thermafil Plus materials.

Should endodontists place dental implants? A national survey of general dentists.

INTRODUCTION: The purpose of this study was to assess whether general dentists support the placement of dental implants by endodontists. METHODS: A 29-item written survey was developed and mailed to 1,500 randomly selected practicing general dentists within the United States to assess whether respondents supported implant placement by endodontists and whether they would refer patients to endodontists for implant placement. Univariate, bivariate, and logistic regression analyses were performed. RESULTS: Three hundred sixty-six subjects completed surveys. Sixty-six percent of respondents opposed endodontists placing implants, and 73% indicated they would not refer patients to an endodontist for implant placement. The following characteristics were associated with respondents who support implant placement (P < .05): yes, willing to refer to an endodontist for implant placement; believes other specialists would support endodontists placing implants; never or sometimes refers patients for molar root canal treatment; and plans to retire in 5 years. CONCLUSIONS: The majority of respondents did not support implant placement by endodontists. As the demand for implant therapy continues to grow, it may be necessary to increase the number of practitioners who place dental implants. However, general dentists' and specialists' attitudes should be further assessed before modifying the scope of endodontic practice to include implant placement.

Apical morphology of the palatal roots of maxillary molars by using micro-computed tomography.

INTRODUCTION: The apical constriction (AC) has been a traditional landmark as an end point of canal preparation and obturation. However, the morphology and incidence of this structure have not been definitively determined. The purpose of this study was to determine these factors by using a noninvasive technology, micro-computed tomography. METHODS: Forty extracted maxillary molar palatal roots were separated and mounted. Each root was scanned with micro-computed tomography. Slices from the scan were computer reconstructed by using special software. This rendered each root three-dimensionally "transparent." Roots were rotated, and the apical canal region was selected. In 2 sessions, trained evaluators identified the AC as to (1) presence (single and tapered) or (2) absence (flaring, parallel, and delta). Evaluator agreement was assessed by Cohen's kappa. Descriptive frequencies were determined for apical constriction presence and morphology. RESULTS: Interagreement and intra-agreement of evaluators were good. In regard to frequency of occurrence, most (65%) canals did not demonstrate an AC. The morphology, in order of most to least, was parallel 35%, single 19%, flaring 18%, tapering 15%, and delta 12%. CONCLUSIONS: From the noninvasive evaluation of our sample it was concluded that an AC was usually not present and that this apical canal region was variable. If this is true with other tooth groups, the AC should not be used as an anatomical marker for preparation and obturation.

Bactericidal activity of stabilized chlorine dioxide as an endodontic irrigant in a polymicrobial biofilm tooth model system.

INTRODUCTION: The purpose of this study was to determine bactericidal efficacy of 0.04% stabilized chlorine dioxide, 3% sodium hypochlorite, 2% chlorhexidine gluconate, and sterile distilled water in a polymicrobial biofilm model. METHODS: Roots of 35 permanent bovine incisors had pulps extirpated, and their apical size and root length were standardized. Teeth were coated with mucin, inoculated with standardized suspensions of Streptococcus sanguinis, Actinomyces viscosus, Fusobacterium nucleatum, Peptostreptococcus micros, and Prevotella nigrescens and incubated anaerobically. Teeth were randomly divided into four groups and rinsed for 3 minutes with 15 mL of irrigant. Biofilms were harvested and spiral-plated on selective media. Numbers of bacteria in the harvested biofilms was determined via the standard spiral-plating methodology. Treatment groups were evaluated using the nonparametric Kruskal-Wallis procedure. Pair-wise comparisons among the four groups and five organisms were made using the Wilcoxon-Mann-Whitney procedure. Adjustments for multiple comparisons were made using the Holm method with p < 0.05. RESULTS: Results provide strong evidence of a significant difference in levels of bactericidal activity associated with the type of irrigant for all five bacterial species tested. Levels of bactericidal activity were significantly higher for the NaOCl group than for the stabilized chlorine dioxide (ClO2) group for S. sanguinis, A. viscosus, and P. nigrescens. Results for F. nucleatum and P. micros were not significant after the adjustment for multiple comparisons. CONCLUSIONS: The triple-inoculation bovine tooth model system is a robust, consistent, and reproducible model system to study polymicrobial biofilms. It should be used with the knowledge expansion of biofilm structure and function as well as the development of antimicrobial protocols.

Should endodontists place implants? A survey of U.S. endodontists.

INTRODUCTION: The purpose of this national study was to assess endodontists' opinions regarding whether endodontists should place dental implants. METHODS: A written survey was developed and mailed to 1505 randomly selected practicing endodontists within the United States. RESULTS: The response rate was 46%. Univariate, bivariate, and logistic regression analyses were performed. Fifty-seven percent of respondents supported endodontists placing implants. Currently 5.7% of respondents place implants. Regression analyses identified the following variables as being positively associated with endodontists placing implants: graduation from an endodontic training program >or=10 years ago (p = .002); interest in placing implants in the future (p = .0001); the belief that implant placement should be incorporated into the endodontic residency curriculum (p < .0001); the belief that general dentists would support endodontists placing implants (p < .0001); and the desire to continue the rapport with a referred patient by placing an implant if the patient's tooth is nonrestorable (p < .0001). CONCLUSIONS: The majority of responding endodontists believed that dental implant placement is within the scope of endodontic practice. Governing bodies of the specialty of endodontics might consider discussing whether formal implant training should be incorporated into future curricula.

Resin-based versus gutta-percha-based root canal obturation: influence on bacterial leakage in an in vitro model system.

OBJECTIVE: This study evaluated the ability of a resin-based system (Resilon/Epiphany) and gutta-percha/sealer with warm vertical or cold lateral compaction to prevent coronal leakage. STUDY DESIGN: A polymicrobial suspension in a dual-chamber model was used. Seventy extracted maxillary incisors were prepared, divided into 4 groups, and obturated: Group 1, lateral compaction/gutta-percha/AH Plus; Group 2, lateral compaction/Resilon; Group 3, continuous wave compaction/gutta-percha/AH Plus; Group 4, continuous wave compaction/Resilon. Upper chambers held a mixed suspension of endodontic pathogens. Apices were suspended in the lower chambers. Leakage was determined daily for 40 days and evaluated for turbidity. Data were analyzed using survival analysis; log-rank test was used to analyze differences in time to leakage. RESULTS: Median time to leakage: 16, 15, 11, and 25 days for Groups 1 to 4 respectively (P = .93, log-rank test). CONCLUSION: No difference in time to leakage among the 4 treatment groups existed.

Antimicrobial susceptibility of monoculture biofilms of a clinical isolate of Enterococcus faecalis.

The purpose of this study was to create a monoculture biofilm of a clinical isolate of Enterococcus faecalis and to determine susceptibility against four antimicrobial irrigants. Biofilms were subjected to 1-, 3-, and 5-minute exposures to one of the following irrigants: 6% sodium hypochlorite (NaOCl), 2% chlorhexidine gluconate (CHX) or one of two new products, <6% NaOCl with surface modifiers (Chlor-XTRA) or 2% CHX with surface modifiers (CHX-Plus) (Vista Dental Products, Racine, WI). It was hypothesized that NaOCl and CHX would be equally effective and that addition of surface modifiers would improve bactericidal activity of the respective irrigants compared to the original formulations. Results indicate that 6% NaOCl and Chlor-EXTRA were significantly superior against E. faecalis biolfilms compared to 2% CHX and CHX-Plus at all time points except five minutes.

A comparison of three nickel titanium rotary systems, EndoSequence, ProTaper universal, and profile GT, for canal-cleaning ability.

Canal preparation is a major step in root canal treatment and is directly related to subsequent disinfection and obturation. In recent years, nickel-titanium rotary systems such as the EndoSequence (Brassler USA, Savannah, GA), the ProTaper Universal (Dentsply/Maillefer, Ballagigues, Switzerland), and the ProFile GT (Dentsply/Maillefer, Ballagigues, Switzerland) have significantly altered root canal instrumentation. EndoSequence has become a very popular system among general practitioners but has not been scientifically tested or compared with other rotary systems that are commonly used by both specialists and general practitioners. The purpose of this study was to compare cleaning effectiveness under scanning electron microscopy (SEM) using three different rotary nickel-titanium instruments: the ProTaper variable taper, the ProFile GT .04 taper, and the EndoSequence .04 taper. Thirty-six extracted mandibular molars were selected for this study. The teeth were randomly divided into three groups. Each group had two noninstrumented teeth that served as controls. All teeth were prepared to a #40 final apical file after manufacturers' instructions. All three systems were used in the traditional "crown-down technique." Teeth were sectioned buccolingually and examined under SEM at 20.0 kV and 500x magnification in the middle third of the canal. Debris was defined as dentin chips, pulp remnants, and particles loosely attached to the root canal wall. Analysis of the SEM images was performed by using a five-score index. Results indicated that there was no difference in cleansing ability of the three file types.

Vital signs of the emergency patient with pulpal necrosis and localized acute apical abscess.

Vital signs aid in assessing patient health and the disease severity. The objectives of this study were to determine changes in vital signs of patients with pulpal necrosis (PN) and acute apical abscess (AAA). The vital signs measured at the emergency visit were blood pressure, heart rate, temperature, and lymphadenopathy. Visual analogue scales (VASs) were used to assess (1) pain and (2) malaise. Emergency treatment was rendered. At a subsequent (baseline) visit and with clinical symptoms resolved, systemic vital sign measurements and VASs were repeated. The presence or absence of swelling with vital signs and VASs of pain and swelling were compared. Compared with baseline, data showed no marked elevation in temperature, blood pressure, or lymphadenopathy, regardless of presence or absence of swelling. VAS measurements of pain and malaise did show statistically significant higher numbers at the emergency appointment, indicating a difference from baseline. Swelling versus no swelling did not differ. Vital signs were not impacted by localized AAA, although pain and malaise were greater. Vital signs might not be useful determinants of treatment or pharmacotherapeutic measures with localized AAA.

Comparison of 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine in the rapid disinfection of polycaprolactone-based root canal filling material.

The purpose of this investigation was to compare the effectiveness of 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine in the rapid disinfection of Resilon pellets. Resilon pellets were randomly selected, contaminated with Enterococcus faecalis, and disinfected with 5.25% sodium hypochlorite, MTAD, or 2% chlorhexidine. Positive and negative controls were used. All samples were air dried, washed in sterile water, placed in centrifuge tubes containing BHI broth, and incubated at 37 degrees C for up to 7 days. Broths were visually checked for turbidity and scored for growth. Samples from each experimental and control group were randomly chosen, plated, incubated at 37 degrees C, and checked visually for growth. If growth occurred, a gram stain was performed to identify bacterial species. Results indicate that 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine were all effective in the rapid disinfection of Resilon and gutta-percha pellets, and a 1-minute immersion was sufficient to disinfect.

Effect of root canal filling/sealer systems on apical endotoxin penetration: a coronal leakage evaluation.

Endotoxin, elaborated by gram-negative organisms, is an important factor in apical periodontitis. The objective of this study was to evaluate the magnitude of endotoxin penetration through root canal treated teeth using a dual chamber model system. Forty-four maxillary anterior teeth were prepared endodontically and canals filled either by lateral condensation or a warm thermoplasticized technique in combination with either Roth's 801 or AH 26 sealer. Teeth were suspended in the model system with a mixed anaerobic bacterial suspension in the upper chamber and HBSS in the lower chamber. The QCL-1000 LAL assay was used to measure endotoxin at 0, 1, 7, 14, and 21 days. Response feature analysis using trapezoidal area under the curve was performed; the four treatment groups were compared using nonparametric methods. Groups differed (p = 0.028), with thermoplasticized root canal filling/Roth's 801 sealer permitting the least apical endotoxin penetration. Results suggest that Roth's 801 sealer may have a role in inhibiting endotoxin penetration.

Maximizing mandibular prosthesis stability utilizing linear occlusion, occlusal plane selection, and centric recording.

The stability of mandibular complete dentures may be improved by reducing the transverse forces on the denture base through linear (noninterceptive) occlusion, selecting an occlusal plane that reduces horizontal vectors of force at occlusal contact, and utilizing a central bearing intraoral gothic arch tracing to record jaw relations. This article is intended to acquaint the reader with one technique for providing stable complete denture prostheses using the aforementioned materials, devices, and procedures.