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1.
Oper Dent ; 48(6): 606-617, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37961016

ABSTRACT

There is a lack of reports in the literature on the long-term clinical performance of ultratranslucent zirconia, especially considering its use in manufacturing monolithic veneers. The purpose of this case series is to describe the aesthetic treatment steps of three patients with minimally invasive ultratranslucent zirconia veneers and to report the clinical findings up to five years. Three patients (woman: 2, man: 1; mean age: 30 years) unsatisfied with their dental aesthetics sought dental treatment. The treatment plan involved cementing ultratranslucent zirconia veneers. Air-abrasion was performed on the internal surface of zirconia with alumina particles coated by silica (silicatization), followed by silane and adhesive applications for the adhesive cementation. All veneers were adhesively cemented to enamel with resin cement (Variolink Esthetic, Ivoclar). The patients were clinically evaluated annually considering the Ryge modified/ California Dental Association criteria. After a mean follow-up of 4.33 years (4-5 years), a survival rate of 100% was detected for the 28 minimally invasive ultratranslucent zirconia veneers cemented in the 3 patients. There were no absolute failures such as debonding, veneer fracture, or secondary caries. Superficial marginal discoloration was observed in one element (maxillary left lateral incisor) of one patient. Ultratranslucent zirconia is a viable option for manufacturing veneers due to its excellent clinical performance and longevity. However, further long-term clinical studies are essential to consolidate this material as an option for esthetic restorations.


Subject(s)
Dental Porcelain , Zirconium , Male , Female , Humans , Adult , Follow-Up Studies , Zirconium/therapeutic use , Cementation
2.
Philos Trans R Soc Lond B Biol Sci ; 378(1887): 20220280, 2023 10 09.
Article in English | MEDLINE | ID: mdl-37598710

ABSTRACT

Sri Lanka has successfully met the challenge of controlling both lymphatic filariasis (LF) and soil-transmitted helminthiases (STH) as public health problems. The primary public health strategy for combatting both conditions has been preventive chemotherapy. The national programme for the elimination of LF implemented five annual rounds of mass chemotherapy in the endemic districts from 2002 to 2006 using a combination of diethylcarbamazine and albendazole. The overall microfilaria rate declined from 0.21% in 2001 before the mass chemotherapy, to 0.06% in 2016, at declaration of elimination of LF as a public health problem by the World Health Organization. Currently Sri Lanka is in the phase of post-validation surveillance. Achieving control of STH has been more difficult. Mass deworming programmes have been implemented for nearly a century, and national-level surveys reported prevalence rates declining from 6.9% in 2003 to 1% in 2017. However, neither of these infections has been completely eliminated. A situation analysis indicates continued transmission of both among high-risk communities. This paper explores the reasons for persistence of transmission of both LF and STH in residual pockets and the measures that are required to achieve long-term control, or perhaps even interrupt transmission in Sri Lanka. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.


Subject(s)
Elephantiasis, Filarial , Helminthiasis , Humans , Elephantiasis, Filarial/epidemiology , Elephantiasis, Filarial/prevention & control , Sri Lanka/epidemiology , Helminthiasis/epidemiology , Helminthiasis/prevention & control , Public Health , Neglected Diseases , Soil
3.
Ir J Psychol Med ; 39(1): 45-53, 2022 03.
Article in English | MEDLINE | ID: mdl-31130153

ABSTRACT

OBJECTIVES: Major depressive disorder (MDD) is a multifactorial syndrome with significant interactions between genetic and environmental factors. This study specifically investigates the association between family history of alcohol problems (FHAP) and family history of depression (FHD), and how these relate to different clusters of depressive symptoms. METHODS: Correlations between FHAP and FHD and different clusters of the Beck Depression Inventory (BDI) were studied. We sampled 333 employees from a general hospital who had been receiving a psychiatric consultation between 2005 and 2012. Analysis of variance (ANOVA) and Analysis of covariance (ANCOVA) models were conducted to explore these correlations. RESULTS: There was a significant positive correlation between FHAP and BDI affective score. This result remained significant even after the adjustment for other variables considered as important factors for MDD, such as gender, age, marital status, education, ethnic group and FHD. More specifically, FHAP was correlated with dissatisfaction and episodes of crying among the affective symptoms. FHAP showed no statistical difference in any of the other clusters score or in the BDI total score. Moreover, as expected, we found a correlation between FHD and BDI total score and Somatic and Cognitive clusters. CONCLUSION: FHAP should be routinely investigated in individuals presenting with depressive symptoms. This is especially important in cases presenting with dissatisfaction and episodes of crying in patients who do not endorse criteria for MDD. Due to study limitations, the findings require replication by neurobiological, epidemiological and clinical studies.


Subject(s)
Alcohol-Related Disorders , Depressive Disorder, Major , Depression , Humans , Psychiatric Status Rating Scales
4.
Biomed Res Int ; 2021: 9926101, 2021.
Article in English | MEDLINE | ID: mdl-34414239

ABSTRACT

Sri Lanka achieved elimination status for lymphatic filariasis in 2016; still, the disease remains a potential public health issue. The present study is aimed at identifying a subperiodic Brugia sp. parasite which has reemerged in Sri Lanka after four decades via molecular-based analysis. Polymerase chain reaction performed with pan-filarial primers specific for the internal transcribed spacer region-2 (ITS-2) of the rDNA of Brugia filarial parasites isolated from human, canine, and feline blood samples yielded a 615 bp band establishing the species identity as Brugia malayi. Comparison of the ITS2 sequences of the reemerged B. malayi isolates with GenBank sequences revealed a higher sequence homology with B. pahangi than B. malayi with similar phylogenetic evidence. However, the mean interspecies Kimura-2-parameter pairwise divergence between the generated Brugia sequences with B. malayi and B. pahangi was less than 3%. During the analysis of parsimony sites of the new ITS2 sequences, substitutions at A36T, A296G, T373A, and G482A made the sequences different from both B. pahangi and B. malayi suggesting the possibility of a new genetic variant or a hybrid strain of B. malayi and B. pahangi. Mosquito dissections and xenomonitoring identified M. uniformis and M. annulifera as vectors of this novel strain of B. malayi circulating among cats, dogs, and humans in Sri Lanka.


Subject(s)
Brugia malayi/classification , DNA, Ribosomal Spacer/genetics , Elephantiasis, Filarial/parasitology , Sequence Analysis, DNA/methods , Animals , Blood/parasitology , Brugia malayi/genetics , Brugia malayi/isolation & purification , Cats , Culicidae/parasitology , DNA, Protozoan/genetics , Dogs , Elephantiasis, Filarial/veterinary , Genetic Variation , Humans , Phylogeny , Population Surveillance , Sri Lanka
5.
Psychopharmacology (Berl) ; 238(11): 3107-3118, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34328516

ABSTRACT

RATIONALE: Cannabis sativa is the most widely used drug by adolescents globally. The recreational use of synthetic cannabinoids by teenagers has also grown in recent years. Despite the wrong perception that exposure to these drugs does not cause harm, repeated exposure to cannabinoids at early stages of life compromises important maturation processes and brain development. Chronic early cannabinoid use has been related to a higher risk of psychiatric outcomes, including cocaine addiction. Evidence suggests that exposure to natural and synthetic cannabinoids during adolescence modifies molecular and behavioral effects of cocaine in adulthood. Responses to cocaine are regulated by epigenetic mechanisms, such as DNA methylation, in the brain's reward regions. However, the involvement of these processes in modulation of the vulnerability to the effects of cocaine induced by prior exposure to cannabinoids remains poorly understood. OBJECTIVES: Investigate whether exposure to the synthetic cannabinoid WIN55,212-2 during adolescence modulates anxiety- and depression-like behavior, memory, and cocaine reward in adult mice. We also evaluated whether exposure to cannabinoids during adolescence modulates the expression of enzymes that are involved in DNA methylation. RESULTS: Exposure to WIN55,212-2 during adolescence did not alter anxiety- or depressive-like behavior. However, prior exposure to cannabinoids inhibited cocaine-induced conditioned place preference without modulating cocaine-induced hyperlocomotion, accompanied by an increase in expression of the enzyme DNA methyltransferase 3a (DNMT3a) in the prefrontal cortex. CONCLUSIONS: Our findings suggest that exposure to WIN55,212-2 during adolescence leads to changes in DNMT3a expression, and this pathway appears to be relevant to modulating the rewarding effects of cocaine.


Subject(s)
Cannabinoids , Cocaine , Animals , Cannabinoids/pharmacology , Cocaine/pharmacology , DNA (Cytosine-5-)-Methyltransferases/metabolism , DNA Methyltransferase 3A , Mice , Prefrontal Cortex/metabolism , Reward
6.
Arq. bras. med. vet. zootec. (Online) ; 72(3): 1000-1008, May-June, 2020. tab
Article in English | LILACS, VETINDEX | ID: biblio-1129715

ABSTRACT

The addition of different oil blends in the feed of finishing pigs was evaluated. Twenty-four castrated male finishing pigs were used in a randomized block design containing four treatments and six replicates. The treatments consisted of: Reference ration (RR) - 100% soybean oil feed; and the combination of the different oils: Blend1 - 50.0% soybean oil (SO), 25.0% flaxseed oil (FO), 12.5% olive oil (OO) and 12.5% canola oil (CO); Blend2 - 25.0% SO, 50.0% FO, 12.5% OO and 12.5% CO; and Blend3 - 25.0% SO, 12.5% FO, 12.5% OO and 50.0% CO. The performance, quantitative and qualitative carcass parameters, fatty acids profile and economic feasibility of the diets were evaluated. The use of blends in the diets did not influence the performance or carcass quality, but increased marbling and carcass yield. The fatty acid profile of the loin presented greater amounts of stearic acid in Blend3 and higher percentage of unsaturated fatty acids in animals fed with Blend1. The fatty tissue presented greater amounts of myristic acid in Blend1 and oleic acid in Blend3. The reference ration was the most economic. The Blends did not affect performance or carcass characteristics and improved the fatty acid profile.(AU)


Foi avaliada a utilização de diferentes blends de óleo em dietas de suínos em terminação. Foram utilizados 24 suínos, machos, castrados, distribuídos em delineamento de blocos ao acaso, com quatro tratamentos e seis repetições. Os tratamentos consistiram de: ração referência (RR) - 100% de ração com utilização de óleo de soja; e a combinação de diferentes óleos: Blend1 - 50,0% de óleo de soja (OS), 25,0% de óleo de linhaça (OL), 12,5% de óleo de oliva (OO) e 12,5% de óleo de canola (OC); Blend2 - 25,0% OS; 50,0% OL; 12,5% OO e 12,5% OC; e Blend3 - 25,0% OS; 12,5% OL; 12,5% OO e 50,0% OC. Foram avaliados os parâmetros de desempenho, a qualidade de carcaça, o perfil de ácidos graxos e a viabilidade econômica. O uso de blends nas dietas não influenciou o desempenho ou a qualidade da carcaça, mas aumentou o marmoreio e o rendimento de carcaça. O perfil de ácidos graxos do lombo apresentou maiores quantidades de ácido esteárico com a utilização do Blend3 e maior porcentagem de ácidos graxos insaturados nos animais alimentados com o Blend1. O tecido adiposo apresentou maiores quantidades de ácido mirístico quando se forneceu o Blend1 e de ácido oleico com o Blend3. A ração testemunha foi a mais econômica. As misturas não afetaram o desempenho e as características de carcaça e melhoraram o perfil de ácidos graxos da carne.(AU)


Subject(s)
Animals , Swine/metabolism , Fatty Acids, Monounsaturated/administration & dosage , Linoleic Acid , Fatty Acids/metabolism , Food, Fortified
7.
Oper Dent ; 45(4): 352-358, 2020 Jul 01.
Article in English | MEDLINE | ID: mdl-32053455

ABSTRACT

CLINICAL RELEVANCE: The Monobond Etch & Prime seems to be an efficient option for adhesive cementation of ultrathin veneers and full crown ceramic with good properties after two years of clinical follow-up. SUMMARY: The use of the self-etching ceramic primer combines the stages of acid conditioning and silanization in cementation procedures of ceramic restorations. The protocol is a simpler and safer alternative to the conventional protocol for surface treatment of silica-based ceramics. This case report describes the steps of an esthetic rehabilitation with ultrathin veneers and full crown based on lithium disilicate treated with a ceramic primer (Monobond Etch & Prime, Ivoclar Vivadent, Schaan, Liechtenstein). After two years of clinical follow-up, the restorations presented satisfactory esthetic and functional performance, color stability, surface and marginal integrity, and absence of cracks and debonding. More research is needed to investigate the clinical performance and longevity of the ceramic restorations treated with self-etching ceramic primers.


Subject(s)
Dental Bonding , Ceramics , Crowns , Dental Porcelain , Dental Veneers , Follow-Up Studies , Materials Testing , Resin Cements , Surface Properties
8.
BMC Nephrol ; 21(1): 38, 2020 01 31.
Article in English | MEDLINE | ID: mdl-32005171

ABSTRACT

BACKGROUND: Chronic Kidney Disease of unknown etiology (CKDu) is prevalent in North Central Province (NCP) of Sri Lanka. Consumption of un-boiled dug well water has been identified as one of the causative factors. This in-vivo study was performed to investigate some of the suspected factors associated with the pathogenesis of CKDu mediated via ground water. METHOD: Rats were given water, collected from high and low disease prevalent areas from the NCP of Sri Lanka and the results compared with those obtained from previously identified low disease prevalent area; Colombo. Blood Urea Nitrogen, creatinine, urinary microalbumin:creatinine ratio together with ALT and AST levels were analyzed and results were compared using one-way ANOVA and paired t-Test. Histopathology was analyzed using non-parametric method. RESULTS: Rats that ingested water from New Town Medirigiriya (NTM) from high disease prevalent NCP reported significantly elevated microalbumin:creatinine ratios compared to other water sources after 8 months, whilst boiled water from NTM had been able to significantly reduce it. Histopathological findings after the 14 months experimental period revealed significantly high tubular lesion index in rats that ingested water from NCP compared to Colombo. Rats that ingested water from high disease prevalent Divuldamana (DD) from NCP showed the highest kidney lesion index though the fluoride content was relatively low in this area compared to other water sources from high disease prevalent NCP. Rats that ingested boiled and un-boiled water from NTM also developed severe lesions whilst the group from Colombo reported the lowest. Low disease prevalent area from NCP, Huruluwewa (HW) also reported elevated liver enzymes and altered renal histopathology. Association of Na+:Ca2+ ratio in the disease progression was not reflected by the current study. Compared to Colombo, high fluoride, calcium and sodium contents were observed in water from high disease prevalent areas. All the water samples were negative for heavy metals. CONCLUSIONS: Though Fluoride is a known kidney toxic agent it cannot be the sole reason for CKDu in NCP, Sri Lanka. Various toxic elements present in NCP water may contribute to different grade of kidney and liver lesions in Wistar rats.


Subject(s)
Drinking Water/adverse effects , Drinking Water/chemistry , Groundwater/chemistry , Renal Insufficiency, Chronic/etiology , Alanine Transaminase/blood , Albuminuria/urine , Animals , Aspartate Aminotransferases/blood , Blood Urea Nitrogen , Calcium/analysis , Creatinine/blood , Creatinine/urine , Drinking Water/administration & dosage , Female , Fluorides/analysis , Hepatitis/blood , Hepatitis/etiology , Hepatitis/pathology , Kidney Tubules/pathology , Male , Random Allocation , Rats , Rats, Wistar , Renal Insufficiency, Chronic/blood , Renal Insufficiency, Chronic/pathology , Renal Insufficiency, Chronic/urine , Sodium/analysis , Sri Lanka
9.
Biomed Res Int ; 2019: 9209240, 2019.
Article in English | MEDLINE | ID: mdl-31139659

ABSTRACT

BACKGROUND: Human dirofilariasis is an emerging zoonosis in many countries. Dirofilariasis caused by Dirofilaria repens may present with diverse clinical manifestations in humans due to aberrant localization of worm lesions causing diagnostic dilemmas. The aim of this retrospective study was to describe and update the demography and clinical spectrum of human dirofilariasis in western Sri Lanka. Nematode or nematode fragments isolated from excision biopsies that were confirmed as D. repens at the Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka, between 2012 and 2018 were included. Data on age, gender, and clinical details were obtained from case files. Identity of worms was established by morphometry and cuticle characteristics on wet-mount preparation. Specimens from unusual case presentations were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. RESULTS: Sixteen nematode specimens isolated from subconjunctiva (n=2), subcutaneous (n=13) and intramuscular (n=1) locations were identified as D. repens by morphometry (average length 11.5 cm) and the characteristic longitudinal striations on cuticle visualized by microscopy. The age distribution of cases ranged from 1 to 65 years with a mean of 21.5. Females were more frequently affected (n=10, 62.5%) and worm locations were commonest in the orbital region (5/16) and scrotum (3/16). Imaging techniques were of use in detecting infections in deeper tissue levels. PCR analysis of DNA extracted from a worm in an intramuscular granuloma of the temporal region elicited the expected band at 484bp for D. repens. CONCLUSIONS: Human dirofilariasis is on an upward trend in incidence. Imaging techniques were of use in clinical diagnosis and molecular speciation in establishing the species identity in unusual case presentations. We suggest a more conservative approach in the management of human dirofilariasis and recommend a one health approach for control.


Subject(s)
Dirofilariasis/epidemiology , Adolescent , Adult , Aged , Animals , Child , Child, Preschool , Dirofilaria/cytology , Dirofilariasis/diagnostic imaging , Dirofilariasis/parasitology , Female , Humans , Infant , Magnetic Resonance Imaging , Male , Middle Aged , Movement , Sri Lanka/epidemiology , Time Factors , Young Adult
10.
Bull Entomol Res ; 109(3): 325-332, 2019 Jun.
Article in English | MEDLINE | ID: mdl-29973304

ABSTRACT

Lipaphis erysimi (L.) Kaltenbach (Hemiptera: Aphididae) is one of the most important pests of brassica crops, mainly causing losses due to sap sucking, toxin injection and viral transmission. Knowledge about the main natural factors that regulate populations of this pest, as well as its critical mortality stage, is crucial for the development of integrated pest management of L. erysimi. Here, we determined the critical stage and key mortality factors for L. erysimi in cabbage using an ecological life table. Causes of mortality at each stage of L. erysimi development were monitored daily in the field for seven seasons. From the experimental data, we determined the key factor and critical stage of mortality through correlation and regression analyses. The nymphal stage, especially first instar nymphs, was critical for L. erysimi mortality. The key mortality factors were, in descending order of importance, physiological disturbances and predation by Syrphidae, Coccinellidae and Solenopsis ants. Therefore, control measures should target early stages of L. erysimi and the use of cabbage cultivars that have negative effects against L. erysimi may be a promising strategy for its management. Our results may be useful for plant geneticists who could develop new cabbage cultivars based on these findings. In addition, conservation measures of the main predators of L. erysimi may contribute to the natural control of this pest.


Subject(s)
Aphids/physiology , Brassica/parasitology , Animals , Aphids/growth & development , Aphids/parasitology , Brazil , Life Cycle Stages , Life Tables , Population Dynamics , Predatory Behavior
11.
Int J Immunogenet ; 42(4): 239-53, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26096648

ABSTRACT

Common variable immunodeficiency (CVID) is the most common clinically manifested primary immunodeficiency, which represents a heterogeneous group of hypogammaglobulinemias of largely unknown molecular defects. The hallmark of the disease is the elevated susceptibility to recurrent infections of respiratory and gastrointestinal tract, mainly due to encapsulated bacteria while a significant proportion of patients with CVID develop autoimmune and lymphoproliferative complications. The primary cause of CVID is still not known. However, a number of distinct genetic defects including in inducible co-stimulator (ICOS), B-cell-activating factor receptor (BAFFR) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) have been identified in a minority of patients with CVID. Mutations in tumour necrosis factor receptor superfamily (TNFRSF) member, TACI, are more frequently found to be associated to the disease in about 10% of patients with CVID, but may require additional immunologic defects for complete expression of the phenotype, as unaffected heterozygotes have also been described. Clinically, patients with TACI mutations could present with the complete spectrum of complications seen in CVID. Recent animal studies have provided substantial information on TACI signalling, yet it still offers an outstanding opportunity for further exploration of the aetiology, as a large part of it remains poorly understood. In this review, we aim at giving an insight into the genetics underlying the CVID and particularly at outlining the role of TACI and its relative contribution to the development of CVID-like phenotypes in human.


Subject(s)
Autoimmune Diseases/genetics , Common Variable Immunodeficiency/genetics , Lymphoproliferative Disorders/genetics , Transmembrane Activator and CAML Interactor Protein/genetics , Autoimmune Diseases/complications , Autoimmune Diseases/immunology , B-Cell Activation Factor Receptor/genetics , B-Cell Activation Factor Receptor/immunology , B-Lymphocytes/immunology , B-Lymphocytes/pathology , Common Variable Immunodeficiency/complications , Common Variable Immunodeficiency/immunology , Humans , Inducible T-Cell Co-Stimulator Protein/genetics , Inducible T-Cell Co-Stimulator Protein/immunology , Lymphoproliferative Disorders/complications , Lymphoproliferative Disorders/immunology , Mutation , Signal Transduction , Transmembrane Activator and CAML Interactor Protein/immunology
13.
Int J Comput Dent ; 17(3): 219-38, 2014.
Article in English, German | MEDLINE | ID: mdl-25558761

ABSTRACT

BACKGROUND AND PURPOSE: Different digital software tools are available today for the purpose of designing anatomically correct anterior and posterior restorations. The current concepts present weaknesses, which can be potentially addressed by more advanced modeling tools, such as the ones already available in professional CAD (Computer Aided Design) graphical software. AIM: This study describes the morphogenic designer (MGD) as an efficient and easy method for digitally designing tooth forms for the anterior and posterior dentition. MATERIALS AND METHOD: Anterior and posterior tooth forms were selected from a collection of digitalized natural teeth and subjectively assessed as "average". The models in the form of STL files were filtered, cleaned, idealized, and re-meshed to match the specifications of the software used. The shapes were then imported as wavefront ".obj" model into Modo 701, software built for modeling, texturing, visualization, and animation. RESULTS: In order to create a parametric design system, intentional interactive deformations were performed on the average tooth shapes and then further defined as morph targets. By combining various such parameters, several tooth shapes were formed virtually and their images presented. CONCLUSION: MGD proved to be a versatile and powerful tool for the purpose of esthetic and functional digital crown designs.


Subject(s)
Computer-Aided Design , Dental Prosthesis Design , Software , Bicuspid/anatomy & histology , Cuspid/anatomy & histology , Esthetics, Dental , Humans , Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Incisor/anatomy & histology , Molar/anatomy & histology , Principal Component Analysis , Therapy, Computer-Assisted , User-Computer Interface
14.
Ceylon Med J ; 58(3): 106-10, 2013 Sep.
Article in English | MEDLINE | ID: mdl-24081170

ABSTRACT

OBJECTIVES: To determine the prevalence of enterobiasis among school children in Ragama Medical Officer of Health (MOH) region and the association between clinical features, potential risk factors and infection status. DESIGN: Cross sectional study. SETTING: School based. Participants 260 school children aged 5-7 years, attending five state schools in the Ragama MOH region. MAIN OUTCOME MEASURES: Prevalence of Enterobius vermicularis infection as diagnosed using adhesive cellophane tapes on the perianal skin on 2 consecutive days. RESULTS: The overall prevalence of enterobiasis was 38%. The risk factors significant on a univariate analysis were male gender, maternal under-education, non-permanency of paternal employment, more household members, more siblings in a family, more persons sleeping with an index child and lack of recent deworming. On a multivariate model more household members, more children in a household, more persons sleeping with the index child, non-permanency of paternal employment and lack of recent deworming were significantly associated with infection. None of the clinical manifestations evaluated (peri-anal itching, insomnia, abdominal pain, and enuresis) showed a significant association with enterobiasis. CONCLUSIONS: Enterobiasis is highly prevalent among primary school children in Ragama.


Subject(s)
Enterobiasis/epidemiology , Child , Child, Preschool , Cross-Sectional Studies , Enterobiasis/prevention & control , Female , Humans , Male , Prevalence , Risk Factors , Socioeconomic Factors , Sri Lanka/epidemiology
16.
J Dent Res ; 91(3): 305-10, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22205635

ABSTRACT

The present investigation hypothesized that the reliability of reduced-thickness monolithic lithium disilicate crowns is high relative to that of veneered zirconia (Y-TZP) and comparable with that of metal ceramic (MCR) systems. CAD/CAM first mandibular molar full-crown preparations were produced with uniform thicknesses of either 1.0-mm or 2.0-mm occlusal and axial reduction, then replicated in composite for standard crown dies. Monolithic 1.0-mm (MON) and 2.0-mm CAD/CAM lithium disilicate crowns, the latter with a buccal thin veneer (BTV) of 0.5 mm, were fabricated and then sliding-contact-fatigued (step-stress method) until failure or suspension (n = 18/group). Crack evolution was followed, and fractography of post mortem specimens was performed and compared with that of clinical specimens. Use level probability Weibull calculation (use load = 1,200 N) showed interval overlaps between MON and BTV. There was no significant difference between the Weibull characteristic failure loads of MON and BTV (1,535 N [90% CI 1,354-1,740] and 1,609 N [90% CI 1,512-1,712], respectively), which were significantly higher than that of Y-TZP (370 N [90% CI 322-427]) and comparable with that of MCR (1,304 N [90% CI 1,203-1,414]), validating the study hypothesis.


Subject(s)
Crowns , Dental Porcelain , Dental Veneers , Computer-Aided Design , Dental Prosthesis Design , Dental Restoration Failure , Dental Stress Analysis , Humans , Materials Testing , Metal Ceramic Alloys , Models, Dental , Survival Analysis , Yttrium , Zirconium
18.
Ceylon Med J ; 56(1): 22-8, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21542430

ABSTRACT

OBJECTIVE: To examine the validity of selected entry level characteristics in relation to the GCE A/L examination as independent predictors of performance of students in medical school. METHODS: A retrospective, analytical study was done at the Faculty of Medicine, University of Kelaniya. Student characteristics at entry were described by sex, the average z-score, General English grade and attempt at GCE A/L examination, and average mark obtained at the English placement test on registration to medical school. Average marks at three summative examinations were used as indicators of performance in medical school. Multivariate analysis using multiple linear regression was carried out using these three outcome measures in relation to four entry point variables as predictors of performance in medical school. Causal path diagrams were constructed using standardised regression coefficients for the whole group and for male and female students separately. RESULTS: The A/L z-score, A/L attempt and English placement test marks were all significant predictors of outcome at the First Examination. Of the variables relating to the A/L examination, the attempt had a much higher path coefficient with performance at the First Examination than the A/L z-score, as did the English marks. Separate path analyses for male and female students showed that while the significance of the relationships remained the same, the magnitude of the correlation was different. CONCLUSIONS: Students who gain admission on their 3rd attempt at the AL examination fare much worse than those admitted to medical school on their 1st attempt. Differences between sexes in examination performance are probably linked to both A/L attempt and English language proficiency.


Subject(s)
Aptitude Tests , Multilingualism , School Admission Criteria/statistics & numerical data , Aptitude Tests/standards , Aptitude Tests/statistics & numerical data , Communication , Education, Medical, Undergraduate/organization & administration , Education, Medical, Undergraduate/statistics & numerical data , Female , Humans , Linear Models , Male , Reproducibility of Results , Schools, Medical/standards , Schools, Medical/statistics & numerical data , Sex Factors , Students, Medical/psychology , Task Performance and Analysis
19.
J Dent Res ; 90(8): 937-52, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21224408

ABSTRACT

The clinical success of modern dental ceramics depends on an array of factors, ranging from initial physical properties of the material itself, to the fabrication and clinical procedures that inevitably damage these brittle materials, and the oral environment. Understanding the influence of these factors on clinical performance has engaged the dental, ceramics, and engineering communities alike. The objective of this review is to first summarize clinical, experimental, and analytic results reported in the recent literature. Additionally, it seeks to address how this new information adds insight into predictive test procedures and reveals challenges for future improvements.


Subject(s)
Dental Porcelain , Dental Prosthesis , Computer-Aided Design , Dental Prosthesis Design , Dental Restoration Failure , Dental Stress Analysis , Dental Veneers , Humans , Materials Testing , Surface Properties , Survival Analysis , Yttrium , Zirconium
20.
J Dent Res ; 90(1): 104-8, 2011 Jan.
Article in English | MEDLINE | ID: mdl-21057036

ABSTRACT

This study tested the hypothesis that all-ceramic core-veneer system crown reliability is improved by modification of the core design. We modeled a tooth preparation by reducing the height of proximal walls by 1.5 mm and the occlusal surface by 2.0 mm. The CAD-based tooth preparation was replicated and positioned in a dental articulator for core and veneer fabrication. Standard (0.5 mm uniform thickness) and modified (2.5 mm height lingual and proximal cervical areas) core designs were produced, followed by the application of veneer porcelain for a total thickness of 1.5 mm. The crowns were cemented to 30-day-aged composite dies and were either single-load-to-failure or step-stress-accelerated fatigue-tested. Use of level probability plots showed significantly higher reliability for the modified core design group. The fatigue fracture modes were veneer chipping not exposing the core for the standard group, and exposing the veneer core interface for the modified group.


Subject(s)
Crowns , Dental Porcelain/chemistry , Dental Prosthesis Design , Post and Core Technique , Yttrium/chemistry , Zirconium/chemistry , Cementation/methods , Computer-Aided Design , Dental Articulators , Dental Restoration Failure , Dental Stress Analysis/instrumentation , Dental Stress Analysis/methods , Dental Veneers , Friction , Humans , Materials Testing , Microscopy, Electron, Scanning , Reproducibility of Results , Resin Cements/chemistry , Stress, Mechanical , Surface Properties , Time Factors , Tooth Preparation/methods , Water/chemistry
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