Primary Cavities Research Articles

Differences in Caries Severity Based on Sociodemographic Factors in Pediatric Patients at Universitas Brawijaya Hospital

Early childhood caries (ECC) is influenced by age and gender, with the severity of primary dental cavities being measured using dmf-t index. Therefore, this research aimed to identify differences in caries severity based on age and gender among pediatric patients at Universitas Brawijaya Hospital. The identification process was conducted through an analytical observational method using secondary data, comprising 71 medical records of pediatric patients receiving treatment in the hospital from April 2021 to November 2022. Medical records were observed by examining the number of teeth with decay, missing, and filling, as well as age and gender. According to the chi-square test results, there were no significant differences in caries severity based on age or gender (p > 0.05). In conclusion, this research showed no differences in caries severity based on sociodemographic factors in pediatric patients.

Catalytic specificity and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa

The escalating drug resistance among microorganisms underscores the urgent need for innovative therapeutic strategies and a comprehensive understanding of bacteria's defense mechanisms against oxidative stress and antibiotics. Among the recently discovered barriers, the endogenous production of hydrogen sulfide (H2S) via the reverse transsulfuration pathway, emerges as a noteworthy factor. In this study, we have explored the catalytic capabilities and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa (PaCGL), a multidrug-opportunistic pathogen chiefly responsible for nosocomial infections. In addition to a canonical l-cystathionine hydrolysis, PaCGL efficiently catalyzes the production of H2S using l-cysteine and/or l-homocysteine as alternative substrates. Comparative analysis with the human enzyme and counterparts from other pathogens revealed distinct structural features within the primary enzyme cavities. Specifically, a distinctly folded entrance loop could potentially modulate the access of substrates and/or inhibitors to the catalytic site. Our findings offer significant insights into the structural evolution of CGL enzymes across different pathogens and provide novel opportunities for developing specific inhibitors targeting PaCGL.

Development characteristics and main controlling factors of Carboniferous volcanic reservoirs in the Shixi area, Junggar Basin

The Carboniferous volcanic reservoirs in the Shixi area of the Junggar Basin are complex and diverse. Identifying the characteristics and main factors controlling high-quality volcanic reservoirs is the key to increasing oil and gas reserves and production in this area. Through core observations, thin section identification, physical property and pore structure analyses, combined with production data, the main controlling factors and development modes of high-quality reservoirs were analysed. The results show that the Carboniferous strata in the Shixi area mainly contain andesite and dacite of overflow facies, followed by volcanic breccia and tuff of explosive facies. Volcanic reservoirs in the study area are high-porosity–low-permeability and medium-porosity–low-permeability reservoirs. Volcanic breccia of explosive facies has the best physical properties, showing the characteristics of high porosity and medium permeability. The reservoir space is mainly composed of gas cavities, corrosion pores and fractures, among which the corrosion pores are the most important reservoir spaces of the Carboniferous volcanic rocks. Lithology and lithofacies, weathering and corrosion, and fractures are the main factors controlling the development of high-quality volcanic reservoirs. Volcanic rocks that had experienced weathering and denudation for a long time developed a large number of secondary corrosion pores due to the corrosion of soluble minerals or volcanic ash. Fractures further improved the physical properties, causing volcanic rocks to eventually develop into weathering crust reservoirs. The physical properties of the volcanic rocks far away from the weathering crust were improved through primary gas cavities and structural fractures, and these volcanic rocks eventually developed into the inner reservoir.

Microscale evolution of reefal microbialites

Reefal microbialites are crusts and infills of microbialites developed within primary cavities of late Quaternary coralgal reef frameworks. In spite of many previous studies, factors controlling mesofabric transitions, particularly from laminated to digitate microbialites but as well as the microscale formation process in relation to microbial communities, have not yet been fully understood. Furthermore, there are still controversies regarding age differences between reef framework growth and microbialite formation. The authors have discussed the macroscale evolution of primary cavities as well as the microscale evolution of reefal microbialites obtained in a middle Holocene reef core drilled off Okinawa Island, south-west Japan, based on petrographic observations using light and scanning electron microscopy with energy dispersive X-ray spectroscopy and radiocarbon (14C) ages of corals and reefal microbialites. The authors’ petrographic observations show that coralgal reef framework growth was followed by encrusting foraminifers and metazoans, coevally with macro-bioerosion and microbioerosion of coralgal frameworks, then finally infilled with an intraskeletal and boring-filling microbialite (IBFM) and encrusted by reefal microbial crusts (RMCs), including structureless and digitate microbialites. The observed macroscale evolution was probably driven in response to progressive changes to reduced light and water circulation in the primary cavities associated with middle Holocene transgression and reef formation. The microfabric of reefal microbialites consists of primary in situ precipitated peloids (spherical micritic clots), voids (primary pores) and allochthonous detrital grains (bioclastic and siliciclastic) fallen from upper reef surfaces. IBFM geopetally infilled inside bioeroded cavities soon after the bioerosion of coralgal frameworks. RMCs have a two-layered microfabric succession, which is composed of the alternation of dense peloidal aggregates and laterally aligned voids in the lower part and the mixing of peloidal aggregates and irregularly and vertically developed voids in the upper part. The authors speculate that the repeated occurrences of laterally aligned voids in the lower part may imply the intermittent pauses of peloidal formation, while peloids accumulated on the irregular outer surfaces may result in the formation of vertically developed voids and digitate surfaces in the upper part. These peloids are probably formed by coccoid sulfate-reducing bacteria in anoxic environments developed by the degradation of bacterial biofilms and organic matters, allowing sulfate reduction and increasing alkalinity, therefore carbonate precipitation. The two-layered microfabric succession generally observed in RMCs may reflect spatial-temporal oxic/anoxic variations in interstitial water and the degree of sulfate ion supply by the gradual closing of primary cavities.

Embryology of the Abdominal Wall and Associated Malformations-AReview.

In humans, the incidence of congenital defects of the intraembryonic celom and its associated structures has increased over recent decades. Surgical treatment of abdominal and diaphragmatic malformations resulting in congenital hernia requires deep knowledge of ventral body closure and the separation of the primary body cavities during embryogenesis. The correct development of both structures requires the coordinated and fine-tuned synergy of different anlagen, including a set of molecules governing those processes. They have mainly been investigated in a range of vertebrate species (e.g., mouse, birds, and fish), but studies of embryogenesis in humans are rather rare because samples are seldom available. Therefore, we have to deal with a large body of conflicting data concerning the formation of the abdominal wall and the etiology of diaphragmatic defects. This review summarizes the current state of knowledge and focuses on the histological and molecular events leading to the establishment of the abdominal and thoracic cavities in several vertebrate species. In chronological order, we start with the onset of gastrulation, continue with the establishment of the three-dimensional body shape, and end with the partition of body cavities. We also discuss well-known human etiologies.

Atraumatic restorative treatment compared to the Hall Technique for occluso-proximal carious lesions in primary molars; 36-month follow-up of a randomised control trial in a school setting

BackgroundAtraumatic Restorative Treatment (ART) and the Hall Technique (HT) are both minimally invasive, non-aerosol generating procedures (non-AGPs). They seem to have never been directly compared, nor has the HT been studied in a non-clinical setting. This study compared the HT and ART restorations placed in a school setting after 36 months.MethodsChildren (5–10 yo) who had a primary molar with a dentinal occluso-proximal, cavitated carious lesion were allocated to the ART (selective removal) or HT arms. Primary outcome: restoration survival over 36-months (using Kaplan–Meier survival analysis, log rank test, and Cox regression). Secondary outcomes: (1) occlusal vertical dimension (OVD) (1, 2, 3, 4 weeks) and (2) child self-reported discomfort; (3) treatment acceptability (immediately following interventions); (4) Child Oral Health Related Quality of Life (OHRQoL), before treatment and after 6 months and (5) a post hoc analysis of time to tooth exfoliation (1, 6, 12, 18, 24, 30, 36 months).ResultsOne-hundred and thirty-one children (ART = 65; HT = 66) were included (mean age = 8.1 ± 1.2). At 36 months, 112 (85.5%) children were followed-up. Primary outcome: restoration survival rates ART = 32.7% (SE = 0.08; 95% CI 0.17–0.47); HT = 93.4% (0.05; 0.72–0.99), p < 0.001; Secondary outcomes: (1) OVD returned to pre-treatment state within 4 weeks; (2) treatment discomfort was higher for the HT (p = 0.018); (3) over 70% of children and parents showed a high acceptability for treatments, with crown aesthetics being a concern for around 23% of parents; (4) Child OHRQoL improved after 6 months; and (5) teeth treated with the HT exfoliated earlier than those in the ART group (p = 0.007).ConclusionsBoth ART and the HT were acceptable to child participants and their parents and all parents thought both restorations protected their child’s tooth. However, the crown appearance concerned almost a quarter of parents in the HT arm. Children experienced less discomfort in the ART group. Although both treatments can be performed in a non-clinical setting and have the advantage of being non-aerosol generating procedures (non-AGPs), the HT had almost three times higher survival rates (93.4%) for restoring primary molar occluso-proximal cavities compared to ART (32.7%).Trial registrationThis trial was registered in ClinicalTrials.gov (NCT02569047), 5th October 2015. https://clinicaltrials.gov/ct2/show/study/NCT02569047?cond=Hall+Technique+Atraumatic+Rest orative+Treatment&draw=2&rank=2.

VANISHING LUNGS IN SARCOID DISEASE

SESSION TITLE: Medical Student/Resident Pulmonary Manifestations of Systemic Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Sarcoidosis is a multi-system disease with an unclear etiology that is characterized by non-caseating granulomas, T lymphocytes and mononuclear phagocytes in involved tissues. Hilar adenopathy is the most common initial manifestation with bullous emphysema being more of a rare outcome with an aggressive course. CASE PRESENTATION: A 39-year-old male smoker presented with recurrent bronchopulmonary infections. He had been prescribed steroids and antibiotics with interval improvement in the past. The patient endorsed shortness of breath on exertion with wheezing and a productive cough with clear phlegm. Vital signs and spot pulse oximetry were within normal range. A physical examination revealed decreased breath sounds throughout all lung fields as well as prolonged expiratory phase however no added sounds were appreciated. Laboratory values were within normal limit. Initial chest x-ray showed hilar adenopathy and follow up computed tomography (CT) scan showed chronic pulmonary nodularity with coalescent regions, predominantly affecting the upper lobes and superior segments of the lower lobes with mediastinal hilar lymphadenopathy. Pulmonary Function Test (PFT) showed severe obstructive disease and hyperinflation with air trapping. He subsequently underwent bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsy. Tissue pathology showed non-caseating granulomatous inflammation confirming sarcoidosis. He was started on oral prednisone with minimal improvement and maximal inhaler therapy was added with initial improvement however later, his symptoms progressed, and he suffered significant decline in lung capacity. The 1 year follow up CT scan revealed early emphysematous changes that progressed quickly over the course of 3 years into severe emphysema and he eventually required supplemental oxygen. DISCUSSION: The bullous form of sarcoidosis was first reported in 1949. The etiology of emphysema is thought to be related to the obstruction of bronchioles from extrinsic pressure due to lymphadenopathy and endobronchial disease, causing peripheral air trapping and alveolar distention. Cavitary lung disease in sarcoidosis may form as a result of infection however true primary cavities formed by sarcoid granulomas of the walls are extremely rare. Most patients had been noted to have bullous changes within 3–4 years of symptom development. The diagnosis of emphysema is made from radiographic appearance, in addition to a decrease in diffusing capacity and lung volumes. Treatment is primarily medical, consisting of corticosteroids and immunosuppressive agents. Bullectomies are performed if disease is localized. In severe disease, lung transplantation is performed as a final option. CONCLUSIONS: Clinicians should be aware of progressive sarcoid with underlying emphysema as managing this group of patients can be particularly challenging given the aggressive nature of the disease. Reference #1: Jeebun V, Forrest IA. Sarcoidosis: An under-recognised cause for bullous lung disease? Eur Respir J. 2009;34(4):999-1001. doi:10.1183/09031936.00084609 Reference #2: Burke RM. Vanishing Lungs: A Case Report of Bullous Emphysema. Radiology. 1937;28(3):367-371. doi:10.1148/28.3.367 Reference #3: Miller A. The vanishing lung syndrome associated with pulmonary sarcoidosis. Br J Dis Chest. 1981;75(2):209-214. DISCLOSURES: No relevant relationships by Mohammed Al-Ourani, source=Web Response No relevant relationships by Yasmeen Obeidat, source=Web Response No relevant relationships by Batarseh Rami, source=Admin input

СОУДАРЕНИЕ КАПЛИ СО СВОБОДНОЙ ПОВЕРХНОСТЬЮ: АКУСТИЧЕСКОЕ ИЗЛУЧЕНИЕ В ТОЛЩЕ ЖИДКОСТИ

An experimental study of the emission of sound by droplets falling into an unperturbed liquid was performed using wideband hydrophones and a high-speed video camera. Collision of a drop with a water surface is accompanied by air entrainment and the formation of underwater gas cavities, which leads to the appearance of surface forces and fast flows, generating extreme accelerations, which are sufficient for resonant acoustic excitation of cavities and emission of sound packets. The sequence of emitted signals contains a shock pulse, as well as one or more sound packets generated by resonant bubbles detached from underwater cavities. The number of resonating bubbles varies from experience to experience, depending on the collision scenario and further behavior, including, in particular, the process of fragmentation of the primary cavities. The dimensions of the bubbles, measured on video frames, correspond to the values calculated in accordance with the Minnaert resonance frequency.

Cavitary retinoblastoma: clinical observations.

A retrospective case series describing the clinical features and treatment outcomes in eye with cavitary retinoblastoma. Case records of patients diagnosed with cavitary retinoblastoma from 2013 to 2017 were reviewed and their demographic details, clinical presentation, and treatment outcomes were analysed. Thirteen tumours from ten eyes of ten patients were included. Mean age at diagnosis was 36 months (median = 30, range = 2-60 months). Mean number of cavities per tumour were two (median 1, range 1-5). Sixty-two percent of tumours had primary cavities, 23% had secondary cavities, while 15% had both types. Mean basal tumour diameter at presentation was 10.9 mm, and at final follow-up was 10.4 mm. Mean tumour thickness at presentation was 7.7 mm, and at final follow-up was 6.5 mm. Majority of tumours (46%) showed type 2 regression pattern. Tumour recurrence was noted in 1(8%) eye. Cavity rupture with release of vitreous seeds was observed in one eye. Two (20%) eyes with vitreous seeds were treated with intravitreal chemotherapy. Two eyes were advised enucleation, one due to tumour recurrence and theother due to persistent vitreous seeds. No patients had metastasis or death. Mean follow-up was 54 months (median 20, SD 66.82, range 3-183). Cavitary tumours have variable presentations, are often associated with vitreous seeds, and in some cases the latter emanates from them as well. Cavitary tumours tend to maintain stable tumour dimensions.

Ultrasonic cavitation erosion of as-sprayed and laser-remelted yttria stabilized zirconia coatings

Cavitation erosion resistance of 8wt.% yttria stabilized zirconia has been investigated in specimens prepared by atmospheric plasma spraying and laser remelting post treatment. The results indicate that as-sprayed coatings involve defects such as primary cavities and initial micro cracks inside a particle and among the interfaces of particles. When the specimens are subjected to cavitation erosion, the micro cracks initiate and coalesce along with chip removals. Laser remelting produces a dense glazed layer with some cracks though the coatings. With the increasing of erosion time, large pieces are delaminated from coating-substrate interface leading to a significant mass loss. However, the resistance of laser remelted coatings to cavitation erosion is significantly improved when they are impregnated with epoxy by vacuum castable mounting. The relationship between cracks formed inside the laser remelted YSZ coatings and their damage mechanism under cavitation is discussed.

Construction of the earliest stromatoporoid framework: Labechiid reefs from the Middle Ordovician of Korea

The Great Ordovician Biodiversification Event (GOBE) involved a remarkable rise of skeletal reefs during the late Middle Ordovician. A new type of skeletal patch reef built by labechiid stromatoporoids is reported from the Yeongheung Formation (Darriwilian) of the Korean Peninsula, part of the eastern North China Block, a hot-spot for late Middle Ordovician diversification of early labechiids. The attachment of laminar labechiids, subordinate peloidal micritic crusts and spiculate sponges, and minor bryozoans on peloidal–intraclastic packstone to grainstone substrates, and upward growth of these organisms by repeated encrustation, resulted in the construction of centimeter-scale domal tight frame structures. These skeletal frames were in turn veneered by larger labechiids, forming sub-meter-scale laminar skeletal reefs with primary cavities. Such skeletal reefs that formed by the encrustation and binding of labechiid stromatoporoids are analogous to the bindstone frameworks of coeval Laurentian reef mounds and skeletal reefs, though they differ markedly in composition, as is apparent in the absence of tabulate corals and markedly lower contribution of bryozoans, both of which were key elements of the Chazy reefs of Laurentia. The Yeongheung reefs described herein represent some of the oldest labechiid skeletal reefs known to date, and formed mainly by the aggregation of early stromatoporoids prior to the arrival of corals and other robust constructors in the region. This discovery provides new information on the evolutionary trends of early skeletal reefs in response to the appearance of new reef-building organisms and their regional distributions during the Ordovician radiation.

PolyHIPE/pullulan composites derived from glycidyl methacrylate and 1,3‐butanediol dimethacrylate‐based high internal phase emulsions

Highly porous composites of poly(glycidyl methacrylate‐co‐1,3‐butanediol dimethacrylate) and pullulan were prepared as semi‐interpenetrating polymer networks by cross‐linking of high internal phase emulsions (HIPEs). HIPEs were prepared by using an aqueous phase made of pullulan dissolved in deionised water. Instead of conventional cross‐linkers such as divinyl benzene, 1,3‐butanediol dimethacrylate was used as a flexible co‐monomer. Morphological and mechanical properties of the porous composites with an initial pullulan loading ranging from 1 to 10 wt % have been investigated. Resulting composites were tested in terms of uniaxial compression stress and it was found out that the use of pullulan and flexible co‐monomer in the HIPE preparation increases the compression modulus from 13.53 to 30.8 MPa. Textural analyses of the resulting composites show that in all cases open cellular foams composed of primary cavities (∼112–74 μm) connected with secondary interconnected pores were produced with a specific surface area in the range of 1.7–3.0 m2 g−1. In addition, the influence of using porogen in the oil phase was investigated. It was found that using a porogen reduces the cavity size diameter from ∼112 to 20 µm and increases the compression modulus from 13.53 to 47.06 MPa. POLYM. ENG. SCI., 55:2636–2642, 2015. © 2015 Society of Plastics Engineers

KRASOVÉ JEVY V HORNINÁCH BĚLOHORSKÉHO SOUVRSTVÍ (TURON, ČESKÁ KŘÍDOVÁ PÁNEV) Z LOMU BŘEZINKA U LETOVIC

Pseudokarstic features are common in clastic sediments at many places of the Bohemian Cretaceous Basin. Occurrences of karstic features which are naturally linked to calcareous sediments are less usual or rather rare. Probably the most extended is the tinyscale Miskovice Karst near Kutná Hora, where macroforms occur. Karstic features of lesser extent in pseudokarstic caves were documented in the Bohemian Paradise and known are as well from the Tichá Orlice and Svitava rivers valleys. Small-sized occurrence of karstic phenomena were found during recent mapping works in the surrounding of Letovice (W Moravia) in the Březinka quarry near Březová n. S. just above the base of the early Turonian Bílá Hora Formation. The karstic features are of a speleotheme character and are represented mainly by sinter crusts, tubercular sinters, concentric spheroidal aggregates and straws. The occurrence of concentric aggregates is tied to primary breccia cavities and, on the other hand, another karstic features occur mainly in cavities of corrosive character. Based on such observation we preliminary interpret the genesis of the secondary carbonates in two distinct phases. A crystallization of the concentric aggregates was connected with primary cavities environment, which were probably restricted to exogenous influences. Sinters, straws and other karstic features were generated during a second phase, characterized by influence of normal exogenous karstic processes.

Applied stratigraphy and carbonate petrography of the Arabescato Orobico dimension stone from the Bergamasc Alps (Calcare Rosso, Italy)

The Arabescato Orobico is a decorative stone and building material from the Bergamasc Alps, Italy. From the geological standpoint it belongs to the Calcare Rosso, latest Ladinian-Early Carnian in age, which is a peritidal tepee-rich limestone strongly modified by superimposed early diagenetic processes, outcropping in Lombardy Southern Alps. In the last twenty-five years four commercial varieties have been available on the market, namely Grigio, Grigio-Rosa, Rosa, and Rosso, whose working and abandoned quarries, are located around the extraction districts of Camerata Cornello, and San Giovanni Bianco in the median Brembana Valley. Until the 1970s of the last century some different historical types, namely Rosso Antico, Rosso Venato, and Venato Finissimo, where extracted around Ardesio, in the Seriana Valley, as well. This paper deals with the stratigraphic analysis based on detailed physical correlations of several marker horizons mainly recognized along abandoned and active quarries, and their carbonate facies analysis. Stratigraphic results permit to divide the Calcare Rosso unit in three lithozones (CR1, CR2, and CR3), with a very low angle onlapping geometry at the top of the Esino Limestone. Southward (basinward) the Calcare Rosso gradually passes to dominant grey peritidal carbonates poor in tepeehorizons corresponding to the lower Breno Fm.. The petrographic characterization of representative samples from Mecca and Cadei quarries, permits to distinguish peculiar textural and compositional features of the four contemporaneous commercial types. As concerns the Grigio we identify almost five different subtypes, respectivelydenominated Grigio Laguna, composed of fossiliferous subintertidal grey to dark grey and black wackestone-packstones, Grigio Granulare, composed of inter-supratidal pisolitic grey grainstonerudstones, Nero Raggiato, very rich in “raggioni”, dark grey to black fibrous-radial early diagenetic calcite, Grigio Laminato composed of poorly to middle deformed antiformal structures, namely embryo to mature tepees, and, finally, Grigio Brecciato, a grey-colored diagenetic-pedogenetic breccia. Remaining types, ascribed to pinkishgrey, Grigio-Rosa, pinkish, Rosa, and reddish, Rosso, colored diagenetic supratidal facies, can be divided into laminated or brecciated subtypes. The former are composed of antiformal syndepositional to early diagenetic structures, i.e. embryo to mature tepees; the brecciated subtypes consist of more diagenetically modified senile tepees passing to breccias. These types present different amounts of sediment filling, including internal calcitic and dolomitic sediments, pisolites, terra-rossa paleosols and green/reddish clays, and early cementation, such as fibrous isopachous crust, “raggioni”, sparry calcite, of the primary and early diagenetic cavities. The stratigraphic organization, and the facies analysis of this carbonate succession, have been used to evaluate the areal and vertical distribution of the Arabescato Orobico commercial types; in this way the Calcare Rosso depositional model is also suitable for geological prospecting and quarrying activities.

Teaching Atraumatic Restorative Treatment in U.S. Dental Schools: A Survey of Predoctoral Pediatric Dentistry Program Directors

The International Dental Federation and World Health Organization have promoted the use of Atraumatic Restorative Treatment (ART) in modern clinical settings worldwide. In the United States, the practice of ART is not believed to be widely used, which may be a result of little attention given to ART training in predoctoral pediatric dentistry curricula in U.S. dental schools. This study investigated the extent of clinical and didactic instruction on ART provided in U.S. dental schools by surveying the predoctoral pediatric dentistry programs in 2010. Of the fifty-seven directors asked to complete the survey, forty-four responded for a response rate of 77 percent. Of these forty-four programs, 66 percent reported providing clinical training on ART, though only 14 percent provide this training often or very often. The types of ART training provided often or very often included interim treatment (18 percent) and single-surface cavities (14 percent) in primary teeth. However, ART was said to be rarely taught as a definitive treatment in permanent teeth (2 percent). Attitude was a major predictor, for clinical training provided and using professional guidelines in treatment decisions were associated with a positive attitude towards ART. These predoctoral pediatric dentistry programs used ART mainly in primary, anterior, and single-surface cavities and as interim treatment. As ART increases access of children to dental care, the incorporation of the ART approach into the curricula of U.S. dental schools should be facilitated by professional organizations.

Microstructuring by a Combination of Micro Impact Extrusion and Shear Displacement Forming

The Collaborative Research Centre SFB/TR 39 PT-PIESA is developing mass production technologies and process chains for the fabrication of aluminium piezo composites, which can be used as raw material for "smart sheet metal" [1]. Microstructuring by forming is a challenging task concerning material flow, tool and process design [2]. In this study, a hybrid forming process combined of micro impact extrusion and shear displacement is presented and discussed. The formed microstructure, depicted in figure 1, consists of ten parallel primary cavities with cross sections of 0.3×0.3 mm² and four larger secondary cavities which are surrounding the primary cavities. High demands are made concerning precision and reproducibility of the cavities' geometry according to the function of the cavities, which is to serve as collets for sensitive piezo rods. The microstructure has to be formed with one stroke of the stamp. Micro backward impact extrusion is chosen for structuring the primary cavities since it allows accurate forming without aligning die plate and stamp due to a flat die plate. Shear displacement forming, which is the selected process for the secondary cavities, requires a structured and aligned die plate but the forming forces are significantly lower than forming the same geometry with an extrusion process which in turn increases the accuracy. The investigations are focused on the characterization of samples formed with the hybrid process in comparison to structures which are formed solely by impact extrusion. Geometric parameters, material flow and process parameters were evaluated to assess the hybrid process. First experiments show promising results, whereas higher degrees of deformation could be reached at lower forming forces. Exemplary, sections for both processes are depicted in figure 2.

螢光抗体法による乳歯根管内及び小児口腔からのBacteroides melaninogenicus菌群とBacteroides fragilis菌群の検出

螢光抗体法による乳歯根管内及び小児口腔からのBacteroides melaninogenicus菌群とBacteroides fragilis菌群の検出

Twenty-five-year atraumatic restorative treatment (ART) approach: a comprehensive overview

BackgroundThe atraumatic restorative treatment (ART) approach was born 25 years ago in Tanzania. It has evolved into an essential caries management concept for improving quality and access to oral care globally.ResultsMeta-analyses and systematic reviews have indicated that the high effectiveness of ART sealants using high-viscosity glass ionomers in carious lesion development prevention is not different from that of resin fissure sealants. ART using high-viscosity glass ionomer can safely be used to restore single-surface cavities both in primary and in permanent posterior teeth, but its quality in restoring multiple surfaces in primary posterior teeth cavities needs to be improved. Insufficient information is available regarding the quality of ART restorations in multiple surfaces in permanent anterior and posterior teeth. There appears to be no difference in the survival of single-surface high-viscosity glass-ionomer ART restorations and amalgam restorations.DiscussionThe use of ART results in smaller cavities and in high acceptance of preventive and restorative care by children. Because local anaesthesia is seldom needed and only hand instruments are used, ART is considered to be a promising approach for treating children suffering from early childhood caries. ART has been implemented in the public oral health services of a number of countries, and clearly, proper implementation requires the availability of sufficient stocks of good high-viscosity glass ionomers and sets of ART instruments right from the start. Textbooks including chapters on ART are available, and the concept is being included in graduate courses at dental schools in a number of countries. Recent development and testing of e-learning modules for distance learning has increasingly facilitated the distribution of ART information amongst professionals, thus enabling more people to benefit from ART. However, this development and further research require adequate funding, which is not always easily obtainable. The next major challenge is the continuation of care to the frail elderly, in which ART may play a part.ConclusionART, as part of the Basic Package of Oral Care, is an important cornerstone for the development of global oral health and alleviating inequality in oral care.

Modeling ductile fracture in metals involving two populations of voids – influence of continuous nucleation of secondary voids upon growth and coalescence of primary voids

This paper is devoted to the study of the influence of the nucleation of small, secondary voids upon the growth and coalescence of large, primary cavities in porous ductile metals. For this purpose, a simple model is considered: a hollow sphere subjected to hydrostatic loading whereby the central hole simulates a large, primary void, and the presence of secondary voids in the surrounding matrix is accounted for by the Gurson–Tvergaard–Needleman homogenized model for plastic porous materials. Continuous nucleation of small voids in the matrix is described by the straightforward phenomenological formula proposed by Pineau and Joly. Initially, the problem is solved analytically, then numerically when a non-uniform distribution of secondary voids develops in the matrix. These elements are used to define a simplified model in which only a small number of internal parameters describe the growth of primary voids coupled with the nucleation, growth and coalescence of secondary voids. Comparisons between the results derived from this simplified model and those obtained through the numerical computations are used to demonstrate the accuracy of the proposed model.

Microleakage and Shear Punch Bond Strength in Class II Primary Molars Cavities Restored with Low Shrink Silorane Based versus Methacrylate Based Composite using Three Different Techniques

This in vitro study aimed to evaluate the gingival microleakage in class II cavities in primary molars restored with a low shrink silorane resin composite (Filtek P90) or a nanohybride composite resin (Filtek supreme XT) using three different techniques, (total bonding, closed or open sandwich techniques) lined by nano-filled resin modified glass ionomer cement RMGIC (Ketac N100). Additionally, the shear punch bond strength between the two types of composite and KNIO0 was also examined. For microleakage test, two standardized class II slot cavities were prepared in proximal surfaces of 60 sound extracted primary molars which were divided into 2 groups of 30 each according to the type of composite. Each group was subdivided into 3 groups (n = 10) according to the restorative technique used. The restored teeth were examined for microleakage after immersion in 2% methylene blue dye using stereomicroscope at 20 X. Microleakage scores among the groups were compared using Kruskal Wallis test followed by pair wise Mann Whitney U test at P < or = 0.05. Thirty disc specimens were prepared for determining the shear punch bond strength between the two composite materials and the KN100. Specimens were divided into 5 groups (n = 6) according to the adhesive protocol. The differences in mean bond strength values in MPa between groups were statistically analyzed using ANOVA followed by pair wise Tukey Post hoc test at P < or = 0. 05. Mode of failure was also evaluated for all groups. Both the silorane resin and nano-composite resin showed superior marginal seal with the total bonding technique compared to closed and open sandwich techniques. The recorded mean shear punch bond strength values showed no statistical significant difference between the two resin composites without or with their adhesive bonding systems when bonded to the nano-ionomer. All specimens showed cohesive mode of failures except for silorane resin with Adper Easy Bond Self Etch Adhesive (AEBSEA) which showed adhesive mode of failure. The best marginal seal was obtained with the total bonding technique using both resin composites. The shear punch bond strength between KN100 and the two composite materials was not affected by either of the used adhesive bonding agent.