Comparative Evaluation of Marginal Leakage of Various Bevel Designs Using Direct Composite Restoration in Fractured Anterior Teeth: An In Vitro Study.

Background and objective Resin-based restorative materials are the backbone of modern restorative dentistry. But in spite of being an excellent material, there are many shortcomings with direct resin restorative materials such as polymerization shrinkage and microleakage that complicate the rate of clinical success. Hence, the aim of the present study is to compare the microleakage caused by composite restorations using two different bevels, primary and zigzag bevels, while restoring fractured anterior teeth. Materials and methodology Thirty non-carious maxillary central incisors were split into two divisions wherein Group I received the primary bevel and Group II received the zigzag bevel. After receiving the bevel, the samples are restored with direct filling composite material (Neo Spectra ST, Dentsply Sirona, Charlotte, NC, USA). The restored samples underwent thermocycling (Holmarc, Kochi, India) and were assessed for microleakage under a stereomicroscope (Leica M205, Wetzlar, Germany). For the statistical analysis, IBM SPSS Statistics for Windows, V. 23.0 (IBM Corp., Armonk, NY) was used. Descriptive statistics were expressed in mean and standard deviation. Analytical statistics including the independent Student t-test was used to assess the difference derived from both groups at p<0.05. The normality of the data was assessed using the Shapiro-Wilk test. Results In the primary bevel, 53.3% of the samples showed first-degree microleakage, and 46.7% showed second-degree microleakage, respectively, and in samples restored using the zigzag bevel, 66.7% of the samples had no microleakage, and 33.3% of the samples had first-degree microleakage. The independent t-test revealed that the microleakage of the zigzag bevel showed a significant difference, being superior to the primary bevel at p<0.01. Conclusion Acknowledging the limitations of the study conducted, both bevel designs had a certain degree of microleakage when restored with composite material in anterior fractured teeth. However, the zigzag bevel produced significantly lesser microleakage as compared to the primary bevel restorations.

Sight impairment registration in Trinidad: trend in causes and population coverage in comparison to the National Eye Survey of Trinidad and Tobago.

BACKGROUND: Little was known about the population coverage and causes of sight impairment (SI) registration within the Caribbean, or the extent to which register studies offer insights into population eye health. METHODS: We compared causes of SI registration in the Trinidad and Tobago Blind Welfare Association (TTBWA) register with findings from the 2014 National Eye Survey of Trinidad and Tobago (NESTT), and estimated registration coverage. Cross-sectional validation studies of registered clients included interviews, visual function and cause ascertainment in July 2013, and interviews and visual function in July 2016. RESULTS: The TTBWA register included 863 people (all ages, 48.1%(n = 415) male) registered between 1951 and 2015. The NESTT identified 1.1%(75/7158) people aged ≥5years eligible for partial or severe SI registration, of whom 49.3%(n = 37) were male. Registration coverage was approximately 7% of the eligible population of Trinidad. Nevertheless, there was close agreement in the causes of SI comparing the register and population-representative survey. Glaucoma was the leading cause in both the register (26.1%,n = 225) and population-based survey (26.1%, 18/69 adults), followed by cataract and diabetic retinopathy. In the validation studies combined, 62.6%(93/151) clients had severe SI, 28.5%(43/151) had partial SI and 9.9%(15/151) did not meet SI eligibility criteria. SI was potentially avoidable in at least 58%(n = 36/62) adults and 50%(n = 7/14) children. CONCLUSION: We report very low register coverage of the SI population, but close agreement in causes of SI to a contemporaneous national population-based eye survey, half of which resulted from preventable or treatable eye disease.

Near- and Far-Field Observation of Phonon Polaritons in Wafer-Scale Multilayer Hexagonal Boron Nitride Prepared by Chemical Vapor Deposition.

Polaritons in layered materials (LMs) are a promising platform to manipulate and control light at the nanometer scale. Thus, the observation of polaritons in wafer-scale LMs is critically important for the development of industrially relevant nanophotonics and optoelectronics applications. In this work, phonon polaritons (PhPs) in wafer-scale multilayer hexagonal boron nitride (hBN) grown by chemical vapor deposition are reported. By infrared nanoimaging, the PhPs are visualized, and PhP lifetimes of ≈0.6 ps are measured, comparable to that of micromechanically exfoliated multilayer hBN. Further, PhP nanoresonators are demonstrated. Their quality factors of ≈50 are about 0.7 times that of state-of-the-art devices based on exfoliated hBN. These results can enable PhP-based surface-enhanced infrared spectroscopy (e.g., for gas sensing) and infrared photodetector applications.

Does age determine the lightness and darkness of tooth shades? A retrospective study.

The study aimed to analyze whether age determines the lightness and darkness of tooth shades. The demand for esthetics has soared to a next level progressively in many developing countries including India; the importance provided to match the tooth shade creates a great difference in the satisfactory outcome of the patient in the field of dentistry. Therefore, this particular study analyzed the differences in tooth shade values based on age factor among the Indian population. 238 individual's case sheets with the age between 18 and 65 years. 18-30 years of age were considered as group 1 (young adults), 31-45 years in group 2 (middle age), and above 45 years in group 3 (older age). The clinical intraoral pictures of the patients which were taken prior to the treatment were obtained and the shade of any one of the upper permanent central incisors was assessed using the Vitapan 3D-Master shade guide, especially the middle portion of the facial surface of the incisors. The collected data were imported to Statistical Package for the Social Sciences, version 17 (IBM Corporation). Chi-square test was used to assess the significance. From the data, 17.2% showed A1 shade, 35.2% A2 shade, 7.5% A3 shade, 5% A4 shade, 7.1% B1 shade, 15.9% B2 shade, 7.1% B3 shade, 3.3% B4 shade, and 1.1% C1 shade. The individuals under the category of above 45 years showed darker tooth shade compared to young adults and middle age population (Chi-square test, P < 0.001). Significant association was established with darker tooth shades by increasing age and vice versa. The older age population showed a higher correlation for dark shade between teeth. The aging process significantly affects the teeth color. Hence, as a dentist, it is important to know about the distribution of tooth shade and its association with age to get an outcome with adequate patient satisfaction.

Association Between Internet Addiction, Depression and Sleep Quality Among Undergraduate Students of Medical and Allied Sciences.

BACKGROUND: The use of the internet is growing rapidly worldwide with easier availability and affordability in developing countries like Nepal. Apart from several benefits, it has also led to deleterious effects on certain individuals' physical and mental well-being. The present study aimed to assess the burden of internet addiction among nursing, dental and medical undergraduates at a medical school, and examine its relationship with depression and sleep quality. METHODS: A cross-sectional study among 494 students pursuing nursing, dental and medical undergraduate courses at the same medical college in Nepal was conducted. The burden of internet addiction, depression, and sleep disturbance was assessed using Young's Internet addiction test, Beck's depression inventory, and Pittsburgh Sleep Quality Index questionnaires respectively. RESULTS: The majority of respondents reported either controlled use of internet or mild problem with internet use. However, 4.7% of respondents reported significant problems due to internet use. Further, about 42.3% reported poor sleep quality, and 8.9% screened positive for depression. In both chi-square and logistic regression analyses, internet addiction was significantly associated with poor sleep quality and depression. CONCLUSION: The study shows that about half of the participants experienced at least some problems and a small but significant proportion of them reported severe problems due to internet use. This warrants the need to address the issue of internet addiction among medical and allied sciences students in Nepal. Further, internet addiction is associated with both depression and poor sleep quality, highlighting a need to develop effective interventions targeting all three problems holistically.

Investigations into the Creation of a Strip Test capable of monitoring Glucose concentration using Tears

Background: To create a strip test to monitor blood sugar levels in diabetics using tears. For most diabetics, the current available methods for testing blood glucose are either invasive, inconvenient or both. A test such as glucose tear strip would improve patient compliance and disease control. Methods: 50 diabetic and 50 non-diabetic subjects, participated in this study. A sample of tears was collected from each subject's right eye using a glass microcapillary tube. Following tear collection, the blood glucose level of each subject was tested and recorded. At the end of sample collection 100 samples of tears were tested for glucose concentration. The results were examined to determine the correlation of glucose in tears to that in blood. Results: Based on this study conducted, the average TG concentration in non-diabetics was found to be 1.89 0.54 mg/dL and in diabetics, 3.10 0.55 mg/dL, whilst the PPBG concentration in non-diabetics and diabetics was found to be 118.60 4.67 mg/dL and 233.98 16.21 mg/dL respectively. Conclusion: There was a significant difference in between the glucose concentration in tears and the glucose concentration in blood. There was a weak correlation between the two variables. The development of a non-invasive, convenient and patient-friendly method of monitoring glucose concentration may not be possible but with advancements in technology, a strips sensitive to low concentrations of glucose present in tears can be developed.

Synthesis and Characterization of Li-C Nanocomposite for Easy and Safe Handling.

Metallic lithium (Li) anode batteries have attracted considerable attention due to their high energy density value. However, metallic Li is highly reactive and flammable, which makes Li anode batteries difficult to develop. In this work, for the first time, we report the synthesis of metallic Li-embedded carbon nanocomposites for easy and safe handling by a scalable ion beam-based method. We found that vertically standing conical Li-C nanocomposite (Li-C NC), sometimes with a nanofiber on top, can be grown on a graphite foil commonly used for the anodes of lithium-ion batteries. Metallic Li embedded inside the carbon matrix was found to be highly stable under ambient conditions, making transmission electron microscopy (TEM) characterization possible without any sophisticated inert gas-based sample fabrication apparatus. The developed ion beam-based fabrication technique was also extendable to the synthesis of stable Li-C NC films under ambient conditions. In fact, no significant loss of crystallinity or change in morphology of the Li-C film was observed when subjected to heating at 300 °C for 10 min. Thus, these ion-induced Li-C nanocomposites are concluded to be interesting as electrode materials for future Li-air batteries.

Room-temperature graphitization in a solid-phase reaction.

Graphitized carbon including graphene has recently become one of the most investigated advanced materials for future device applications, but a prerequisite for broadening its range of applications is to lower its growth temperature. Here we report a great decrease in graphitization temperature using the well-known catalyst Ni. Amorphous carbon films with Ni nanoparticles (NPs) were deposited, using a simple one-step magnetron sputtering method, onto microgrids and a SiO2/Si substrate for transmission electron microscopy (TEM) and Raman spectroscopy analyses, respectively. The amorphous carbon surroundings and locations between the Ni NPs started to become graphitized during the film deposition even at room temperature (RT) and 50 °C. The graphitization was confirmed by both high-resolution TEM (HR-TEM) and Raman 2D peak analyses. The increase in the relative amount of Ni in the amorphous carbon film led to the partial oxidation of the larger Ni NPs, resulting in less graphitization even at an elevated deposition temperature. Based on the detailed HR-TEM analyses, a decreased oxidation of NPs and enhanced solubility of carbon into Ni NPs were believed to be key for achieving low-temperature graphitization.

Takayasu's Arteritis with Subcutaneous Nodules in a 4-year -old Child: A Case Report.

A 4-year-old girl who presented with pain in the abdomen, subcutaneous nodule, fever and was later diagnosed with Takayasu arteritis . Oral corticosteroid and methotrexate were started. Childhood TA should be kept in differential diagnosis when presented with subcutaneous nodules and increased acute phase reactants.

National Eye Survey of Trinidad and Tobago (NESTT): prevalence, causes and risk factors for presenting vision impairment in adults over 40 years.

AIM: To estimate the prevalence, causes and risk factors for presenting distance and near vision impairment (VI) in Trinidad and Tobago. METHODS: This is a national, population-based survey using multistage, cluster random sampling in 120 clusters with probability-proportionate-to-size methods. Stage 1 included standardised, community-based measurement of visual acuity. Stage 2 invited all 4263 people aged ≥40 years for comprehensive clinic-based assessment. The Moorfields Eye Hospital Reading Centre graded fundus photographs and optical coherence tomography images independently. RESULTS: The response rates were 84.2% (n=3589) (stage 1) and 65.4% (n=2790) (stage 2), including 97.1% with VI. The mean age was 57.2 (SD 11.9) years, 54.5% were female, 42.6% were of African descent and 39.0% were of South Asian descent. 11.88% (95% CI 10.88 to 12.97, n=468) had distance VI (logarithm of the minimum angle of resolution [logMAR] >0.30), including blindness (logMAR >1.30) in 0.73% (95% CI 0.48 to 0.97, n=31), after adjustment for study design, non-response, age, sex and municipality. The leading causes of blindness included glaucoma (31.7%, 95% CI 18.7 to 44.8), cataract (28.8%, 95% CI 12.6 to 45.1) and diabetic retinopathy (19.1%, 95% CI 4.2 to 34.0). The leading cause of distance VI was uncorrected refractive error (47.4%, 95% CI 43.4 to 51.3). Potentially avoidable VI accounted for 86.1% (95% CI 82.88 to 88.81), an estimated 176 323 cases in the national population aged ≥40 years. 22.3% (95% CI 20.7 to 23.8, n=695) had uncorrected near VI (logMAR >0.30 at 40 cm with distance acuity <0.30). Significant independent associations with distance VI included increasing age, diagnosed diabetes and unemployment. Significant independent associations with near VI included male sex, no health insurance and unemployment. CONCLUSIONS: Trinidad and Tobago's burden of avoidable VI exceeds that of other high-income countries. Population and health system priorities are identified to help close the gap.

The Mo catalyzed graphitization of amorphous carbon: an in situ TEM study.

For the fabrication of graphene-based nano-scale interconnects, precise control over their position and proper nanoscale soldering are essential. In this work, we report the Joule heat-induced conversion of amorphous carbon to graphene in an in situ TEM setup, using Mo as a catalyst. The catalytic role of Mo during graphene formation has been less explored compared to other metals like Cu or Ni. Compared to metals like Cu, Mo is less subject to electromigration and brittleness, making it suitable for high-temperature electronics. We found that during the electromigration of Mo, amorphous carbon nanofibers (CNFs) can be converted to highly crystalline few-layered graphene. It was also found that during the graphene formation process, agglomerated Mo particles can be effectively channeled to the end of graphene by voltage-driven electromigration. An agglomerated Mo particle between the probe and graphene acted as a soldering agent, providing the prospect of the further exploration of Mo as a nanoscale soldering material. This work explores the double role of Mo: as a catalyst for graphene synthesis and as a soldering material.

A survey of the knowledge, attitude, and awareness about the principal choice of intracanal medicaments among the general dental practitioners and nonendodontic specialists.

BACKGROUND: Removal of the microbial organisms from the root canal system is a prerequisite for the successful outcome of any root canal treatment. Use of an effective intracanal medicament will assist in the disinfection of the root canal system. Intracanal medicaments have been used to disinfect root canals between appointments and reduce interappointment pain. MATERIALS AND METHODS: A questionnaire survey was conducted to evaluate the knowledge, attitude, and awareness about the principal choice of intracanal medicaments among general dental practitioners and nonendodontic specialists. The questionnaire consisted of 11 questions related to intracanal medicaments in Endodontics. It was distributed to 75 general dental practitioners and 75 other specialists (nonendodontists). RESULTS: In the present study, the authors observed that the knowledge level among the study participants was moderately satisfying. However, the need for more education of the dentists with regard to the intracanal medicaments was perceived. DISCUSSION: Correct knowledge of intracanal medicaments would help the practitioners to decide the apt material of choice as intracanal medicaments in different clinical situations. CONCLUSION: The present study highlighted the need for more continuing dental education programs with active participation of general practitioners and nonendodontic specialists to update themselves.

Health system dynamics analysis of eyecare services in Trinidad and Tobago and progress towards Vision 2020 Goals.

Avoidable blindness is an important global public health concern. This study aimed to assess Trinidad and Tobago's progress towards achieving the Pan American Health Organization, 'Strategic Framework for Vision 2020: The Right to Sight-Caribbean Region,' indicators through comprehensive review of the eyecare system, in order to facilitate health system priority setting. We administered structured surveys to six stakeholder groups, including eyecare providers, patients and older adult participants in the National Eye Survey of Trinidad and Tobago. We reviewed reports, registers and policy documents, and used a health system dynamics framework to synthesize data. In 2014, the population of 1.3 million were served by a pluralistic eyecare system, which had achieved 14 out of 27 Strategic Framework indicators. The Government provided free primary, secondary and emergency eyecare services, through 108 health centres and 5 hospitals (0.26 ophthalmologists and 1.32 ophthalmologists-in-training per 50 000 population). Private sector optometrists (4.37 per 50 000 population), and ophthalmologists (0.93 per 50 000 population) provided 80% of all eyecare. Only 19.3% of the adult population had private health insurance, revealing significant out-of-pocket expenditure. We identified potential weaknesses in the eyecare system where investment might reduce avoidable blindness. These included a need for more ophthalmic equipment and maintenance in the public sector, national screening programmes for diabetic retinopathy, retinopathy of prematurity and neonatal eye defects, and pathways to ensure timely and equitable access to subspecialized surgery. Eyecare for older adults was responsible for an estimated 9.5% (US$22.6 million) of annual health expenditure. This study used the health system dynamics framework and new data to identify priorities for eyecare system strengthening. We recommend this approach for exploring potential health system barriers to addressing avoidable blindness, and other important public health problems.

The National Eye Survey of Trinidad and Tobago (NESTT): Rationale, Objectives and Methodology.

PURPOSE: This paper describes the rationale, study design and procedures of the National Eye Survey of Trinidad and Tobago (NESTT). The main objective of this survey is to obtain prevalence estimates of vision impairment and blindness for planning and policy development. METHODS: A population-based, cross-sectional survey was undertaken using random multistage cluster sampling, with probability-proportionate-to-size methods. Eligible participants aged 5 years and older were sampled from the non-institutional population in each of 120 cluster segments. Presenting distance and near visual acuity were screened in their communities. People aged 40 years and older, and selected younger people, were invited for comprehensive clinic assessment. The interview included information on potential risk factors for vision loss, associated costs and quality of life. The examination included measurement of anthropometrics, blood glucose, refraction, ocular biometry, corneal hysteresis, and detailed assessment of the anterior and posterior segments, with photography and optical coherence tomography imaging. Adult participants were invited to donate saliva samples for DNA extraction and storage. RESULTS: The fieldwork was conducted over 13 months in 2013-2014. A representative sample of 10,651 individuals in 3410 households within 120 cluster segments identified 9913 people who were eligible for recruitment. CONCLUSION: The study methodology was robust and adequate to provide the first population-based estimates of the prevalence and causes of visual impairment and blindness in Trinidad and Tobago. Information was also gathered on risk factors, costs and quality of life associated with vision loss, and on normal ocular parameters for the population aged 40 years and older.

Addressing ethical challenges in the Genetics Substudy of the National Eye Survey of Trinidad and Tobago (GSNESTT).

BACKGROUND: The conduct of international collaborative genomics research raises distinct ethical challenges that require special consideration, especially if conducted in settings that are research-naïve or resource-limited. Although there is considerable literature on these issues, there is a dearth of literature chronicling approaches taken to address these issues in the field. Additionally no previous ethical guidelines have been developed to support similar research in Trinidad and Tobago. METHODS: A literature review was undertaken to identify strategies used to address common ethical issues relevant to human genetics and genomics research in research-naïve or resource-limited settings. Strategies identified were combined with novel approaches to develop a culturally appropriate, multifaceted strategy to address potential challenges in the Genetics Substudy of the National Eye Survey of Trinidad and Tobago (GSNESTT). RESULTS: Regarding the protection of study participants, we report a decision to exclude children as participants; the use of a Community Engagement and Sensitization Strategy to increase the genetic literacy of the target population; the involvement of local expertise to ensure cultural sensitivity and to address potential comprehension barriers in informed consent; and an audit of the informed consent process to ensure valid consent. Concerning the regulation of the research, we report on ethics approvals from relevant authorities; a Materials Transfer Agreement to guide sample ownership and export; and a Sample Governance Committee to oversee data use and data access. Finally regarding the protection of the interests of scientists from the host country, we report on capacity building efforts to ensure that local scientists have access to data collected through the project and appropriate recognition of their contributions in future publications. CONCLUSION: This paper outlines an ethical framework for the conduct of population-based genetics and genomics research in Trinidad and Tobago; highlights common issues arising in the field and strategies to address these.

Three-dimensional Quantitative Porosity Characterization of Syringe- versus Hand-mixed Set Epoxy Resin Root Canal Sealer

The aim of the present study was to compare the porosity characteristics of AH Plus Jet(tm) syringe-mix and the conventional hand-mixed AH Plus root canal sealers by three-dimensional quantitative high-resolution micro-computed tomography (micro-CT). Seven test specimens were prepared from each tested sealer by a single operator following the manufacturer's instructions and poured into pre-lubricated plastic split-ring moulds. Set sealer test specimens were scanned using a micro-CT device and the shadow images were reconstructed into cross-sectional slices. The evaluated parameters were (i) total pore count, (ii) total pore volume and mean pore volume, (iii) total porosity (% of pore volume in relation to total sealer volume) and (iv) mean pore distance to the sealer lateral external surface. In both groups, most pores were localized within the external sealer perimeter (0.05 mm from the external surface). Hand-mixed AH Plus specimens showed statistically significant higher mean total pore count, total pore volume and total porosity (p=0.001) than the syringe-mixed specimens. However, mean pore sizes in AH Plus syringe-mixed specimens were significantly higher (p=0.046) than the AH Plus hand-mixed counterparts. Hand-mixed AH Plus was associated with higher total mean pore count, volume and total porosity compared to syringe mixed AH Plus.

Resumo O objetivo do presente estudo foi comparar a porosidade do AH Plus Jet(tm) dotado de misturador automático com o AH Plus convencional manipulado a mão a partir de um método quantitativo de microtomografia computadorizada (micro-CT). Para cada cimento, sete espécimes foram preparados por um único operador, seguindo as instruções do fabricante, e inseridas em anéis de plástico. Após o tempo de presa, os cimentos foram escaneados utilizando o micro-CT e as imagens foram reconstruídas. Os parâmetros avaliados foram (i) contagem total de poros, (ii) volume total de poros e média dos volumes dos poros, (iii) porosidade total (% de volume de poros em relação ao volume total do cimento) e (iv) distância média dos poros em relação ao perímetro externo (0,05 mm da superfície externa). O AH Plus manipulado a mão apresentou maior número de poros, maior volume total de poros e porosidade total (p=0,001) comparado com o AH Plus com misturador. No entanto, a média de tamanho dos poros foi estatisticamente superior no AH Plus com misturador quando comparado com o AH Plus manipulado a mão (p=0,046). O AH Plus manipulado a mão foi associado com uma maior média de poros, volume e porosidade quando comparado com o AH Plus com misturador.

A retrospective study on the outcomes of cataract surgery in an Eastern Regional Health Authority hospital of Trinidad and Tobago.

Background. Worldwide, cataract is a major cause of blindness. The paper aims to evaluate factors associated with borderline and poor outcomes of cataract surgery at an Eastern Regional Health Authority (ERHA) hospital in Trinidad and Tobago. Materials and Methods. A hospital-based, retrospective study was done on 401 patients who had undergone cataract surgery (unilateral and bilateral) at an ERHA Hospital between March 2009 and September 2014. Data was collected on variables concerning demographic, medical history, surgical history, ocular findings and visual acuity (VA). The outcome variable of interest was Snellen's post-operative (presenting) VA which was transformed into a dichotomous variable with borderline and poor outcomes as one and good outcomes as the other. Data were analysed using univariate and multivariate logistic regression analyses. Results. Good outcome (presenting VA 6/18 or better) was seen in 350 (67%) eyes. The fitted model consisted of ocular co-morbidity (OR =2.133; 95% CI [1.346-3.380]), hypertension (OR = 0.520; 95% CI [0.381-0.928]), surgical procedure (OR = 1.56; 95% CI [1.004-2.425]), good preoperative VA (OR = 0.388, 95% CI [0.211-0.714]), borderline preoperative VA (OR = 0.485; 95% CI = [0.278-0.843]) and year of first visit to clinic (OR = 2.243; 95% CI [1.215-4.141]). Conclusion. There is a need for community-based outreach to increase awareness of eye health and diseases. It is recommended that the general population is encouraged to take responsibility for personal management. The facilities at the Hospital should also be enhanced.

Influence of Irrigation Sequence on the Adhesion of Root Canal Sealers to Dentin: A Fourier Transform Infrared Spectroscopy and Push-out Bond Strength Analysis.

INTRODUCTION: There is a lack of evidence on the chemical interaction between sealers and dentin. The influence of irrigation on the chemical interaction between root canal sealers and dentin was analyzed by using Fourier transform infrared spectroscopy (FTIRS) and measurement of dislocation resistance. METHODS: Single-rooted teeth (n = 120) were instrumented with 3% NaOCl as the irrigant and divided into 4 groups (n = 30) on the basis of irrigation protocol: group 1, 3% NaOCl, 17% EDTA, water; group 2, 17% EDTA, 3% NaOCl, water; group 3, 3% NaOCl, QMix, water; group 4, 3% NaOCl, water. Each group was divided into 3 subgroups (n = 10) on the basis of the root canal sealer: A, epoxy resin (AH Plus); B, silicone (RoekoSeal); C, calcium hydroxide (Sealapex). The dislocation resistance was assessed by using push-out bond strength test. The data were statistically analyzed by three-way analysis of variance and Holm-Sidak tests (P = .05). Dentin powder treated as per the conditioning protocols mentioned was mixed with the sealers and analyzed by FTIRS. RESULTS: A significant interaction was observed between irrigation protocol, type of sealer, and root segment (P < .001) for AH Plus but not for RoekoSeal and Sealapex (P > .05). AH Plus showed the highest bond strength (P < .05). FTIRS showed chemical bonding between AH Plus and dentinal collagen. In groups 2 and 4, no chemical bonding was observed. CONCLUSIONS: Bond strength of sealers is differentially affected by the irrigation protocol. The epoxy resin sealer AH Plus chemically bonds to dentinal collagen. This interaction is influenced by the irrigation protocols.

Opening of triangular hole in triangular-shaped chemical vapor deposited hexagonal boron nitride crystal.

In-plane heterostructure of monolayer hexagonal boron nitride (h-BN) and graphene is of great interest for its tunable bandgap and other unique properties. Here, we reveal a H2-induced etching process to introduce triangular hole in triangular-shaped chemical vapor deposited individual h-BN crystal. In this study, we synthesized regular triangular-shaped h-BN crystals with the sizes around 2-10 µm on Cu foil by chemical vapor deposition (CVD). The etching behavior of individual h-BN crystal was investigated by annealing at different temperature in an H2:Ar atmosphere. Annealing at 900 °C, etching of h-BN was observed from crystal edges with no visible etching at the center of individual crystals. While, annealing at a temperature ≥ 950 °C, highly anisotropic etching was observed, where the etched areas were equilateral triangle-shaped with same orientation as that of original h-BN crystal. The etching process and well-defined triangular hole formation can be significant platform to fabricate planar heterostructure with graphene or other two-dimensional (2D) materials.

Pain after single-visit root canal treatment with two single-file systems based on different kinematics--a prospective randomized multicenter clinical study.

OBJECTIVES: The aim of this study is to evaluate the posttreatment pain after instrumentation of root canals with a single-file reciprocating (RECIPROC, VDW, Germany) or rotary (One Shape, MicroMega, France) file system. MATERIALS AND METHODS: Six hundred forty patients were assessed for eligibility, and 624 patients were included in this study. The teeth were randomly allocated to one of the instrumentation protocols. The teeth underwent routine root canal treatment after which patients were discharged with a questionnaire to gather data about the incidence (yes/no), nature (mild, moderate, or severe), and duration of pain (days). The data were analyzed using statistical analyses (preoperative pain scores by Mann-Whitney U test, incidence and intensity of pain by chi-squared test, intake of analgesics, and duration of pain by Student's t test) with P = 0.05. RESULTS: Pain analysis was performed for 605 patients (311 males and 294 females) as 5 patients were excluded due to sealer extrusion and 14 were lost to follow-up. The mean age of the patients was 31 ± 2 years. There was significant difference in the incidence of postoperative pain (P < 0.001). There was significant difference in the number of patients who had mild (P = 0.001), moderate (P = 0.002), and severe (P = 0.001) pain between the two groups. Intensity of pain showed significant difference, with patients in the One Shape group (40.5 %) reporting more values of severe pain (P = 0.002); the percentage of patients who took analgesics was significantly higher in the One Shape group (40.5 %) than in the Reciproc group (19.3 %) (P = 0.002). There was no significant difference in the duration of postoperative pain between the two groups when the pain was mild (P = 0.301), but One shape showed significantly longer duration of moderate (P = 0.001) and severe pain (P = 0.002). CONCLUSIONS: Reciproc showed significantly less intensity and duration of posttreatment pain compared to One Shape. CLINICAL RELEVANCE: Reciprocation movement offers a more predictable and safer approach of root canal preparation, in addition to producing less postoperative pain. The need for patients to take analgesics may reduce following this approach.