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1.
Traffic Inj Prev ; : 1-10, 2024 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-38996033

RESUMO

OBJECTIVE: Using benzodiazepines and certain antidepressants is associated with an increased risk of motor vehicle crashes due to impaired driving skills. Hence, several countries prohibit people who use these drugs from driving. Traffic regulations for driving under the influence of these drugs are, however, largely based on single-dose studies with healthy participants. The effects of drugs on chronic users may be different because of potential development of tolerance or by adapting behavior. In this study, we test the effects of anti-depressants, hypnotics, or anxiolytics use on driving performance in patients who use these drugs for different durations and compare the effects to healthy controls' performance. METHODS: Sixty-six healthy controls and 82 medication users were recruited to perform four drives in a driving simulator. Patients were divided into groups that used anti-depressants, hypnotics, or anxiolytics, for shorter or longer than 3 years (i.e. LT3- or LT3+, respectively). The minimum term of use was 6 months. Driving behavior was measured in terms of longitudinal and lateral control (speed variability and Standard Deviation of Lateral Position: SDLP), brake reaction time, and time headway. Impaired driving performance was defined as performing similar to driving with a Blood Alcohol Concentration of 0.5‰ or higher, determined by means of non-inferiority analyses. RESULTS: Reaction time analyses revealed inconclusive findings in all groups. No significant performance differences between matched healthy controls, LT3- (n = 2), and LT3+ (n = 8) anxiolytics users were found. LT3+ antidepressants users (n = 12) did not perform inferior to their matched controls in terms of SDLP. LT3- hypnotics users (n = 6) showed more speed variability than their matched healthy controls, while this effect was not found for the LT3+ group (n = 14): the latter did not perform inferior to the healthy controls. Regarding Time Headway, no conclusions about the LT3- hypnotics group could be drawn, while the LT3+ group did not perform inferior compared to the control group. CONCLUSIONS: The small number of anxiolytics users prohibits drawing conclusions about clinical relevance. Although many outcomes were inconclusive, there is evidence that some elements of complex driving performance may not be impaired (anymore) after using antidepressants or hypnotics longer than 3 years.

2.
J Dent Res ; 93(10): 943-9, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25048250

RESUMO

The aim of this meta-analysis, based on individual participant data from several studies, was to investigate the influence of patient-, materials-, and tooth-related variables on the survival of posterior resin composite restorations. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a search resulting in 12 longitudinal studies of direct posterior resin composite restorations with at least 5 years' follow-up. Original datasets were still available, including placement/failure/censoring of restorations, restored surfaces, materials used, reasons for clinical failure, and caries-risk status. A database including all restorations was constructed, and a multivariate Cox regression method was used to analyze variables of interest [patient (age; gender; caries-risk status), jaw (upper; lower), number of restored surfaces, resin composite and adhesive materials, and use of glass-ionomer cement as base/liner (present or absent)]. The hazard ratios with respective 95% confidence intervals were determined, and annual failure rates were calculated for subgroups. Of all restorations, 2,816 (2,585 Class II and 231 Class I) were included in the analysis, of which 569 failed during the observation period. Main reasons for failure were caries and fracture. The regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces.


Assuntos
Resinas Compostas/química , Materiais Dentários/química , Restauração Dentária Permanente/normas , Suscetibilidade à Cárie Dentária , Falha de Restauração Dentária , Humanos , Fatores de Risco , Análise de Sobrevida , Fatores de Tempo
3.
Clin Oral Investig ; 18(7): 1785-92, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24327235

RESUMO

AIM: The aim of this study is to evaluate the effect of ozone and fluoride varnish on occlusal caries in primary molars in a split-mouth study. MATERIALS AND METHODS: Caries risk was estimated by treating Public Dental Health Service dentists. Children with occlusal caries with Ekstrand index scores ≤3 (VI ≤3) were included. Selection of caries lesions was discontinued for ethical reasons due to non-acceptable clinical results during the follow-up. In the continued evaluation pairs of teeth with non-cavitated caries lesions, Ekstrand score ≤2a (VI ≤2) were selected. Fifty pairs of carious primary molars were included, 18 boys and 15 girls (mean 4.7 years, range 3-8). At baseline, the lesions were assessed by visual inspection (VI) and laser-induced fluorescence (LF), in each pair to treatment with 40 s ozone (HealOzone(TM), 2,100 ppm) or fluoride varnish Duraphat®. The treatments and evaluations were repeated at 3, 6 9 months and evaluations only at 12 months. RESULTS: Medium-high caries risk was observed in VI ≤3 children and low-medium risk in VI ≤2a children. In the 15 pairs VI ≤3 lesions, 8 treated with ozone and 9 with fluoride progressed to failure. In the 35 pairs VI ≤2a lesions, one lesion failed. Median baseline LF values in the VI ≤3 group were 76 and 69, for ozone and fluoride lesions, respectively, and 21 and 19 in the VI ≤2a group. At 12 months, LF values in the VI ≤2a group were 15 and 18. No improvement or difference in LF values was found over time between the caries lesions treated with ozone or fluoride. CONCLUSIONS: Neither ozone nor fluoride varnish treatments stopped the progression of caries in cavitated lesions. In low and medium caries risk children, non-cavitated lesions following both treatments showed slight or no progression. The use of ozone or fluoride varnish treatments in this regime as caries preventive method, added to the daily use of fluoridated toothpaste, to arrest caries progression in primary molars must therefore be questioned.


Assuntos
Cariostáticos/uso terapêutico , Cárie Dentária/prevenção & controle , Fluoretos Tópicos/uso terapêutico , Ozônio/uso terapêutico , Fluoreto de Sódio/uso terapêutico , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Dente Molar , Dente Decíduo , Resultado do Tratamento
4.
J Dent ; 37(6): 449-53, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19342147

RESUMO

OBJECTIVE: The aim was to evaluate the antibacterial effect of ozone on cariogenic bacterial species with and without the presence of saliva and a possible effect on the salivary proteins. METHODS: Suspensions of Actinomyces naeslundii (ACTCC 12104(T)), Lactobacilli casei (N CTC 151) and Streptococcus mutans (NCTC 10449), in salt buffer or in saliva, were exposed to ozone gas delivered by the ozone generator Healozone 2130C. Aliquots of the suspensions were taken after 10, 30 and 60s ozone exposures and cultivated on agar plates. Initial number of bacteria per ml was 8.0 x 10(7) (SD 2.2 x 10(7)) (A. naeslundii), 1.0 x 10(8) (SD 3.1 x 10(6)) (L. casei) and 1.0 x 10(8) (SD 7.0 x 10(5)) (S. mutans), respectively. The proteins were separated by SDS electrophoresis and visualized by silver staining. RESULTS: In salt buffer 92%, 73% and 64% of the initial numbers of A. naeslundii, S. mutans and L. casei, respectively, were killed already after 10s ozone exposure, while approximately 99.9% of the bacteria were dead after a 60s exposure. After 10 and 30s, but not after 60s exposure to ozone, S. mutans and L. casei were less efficiently killed in saliva compared to the salt buffer. Various saliva proteins were degraded by ozone after a 60s exposure. CONCLUSIONS: The cariogenic species S. mutans, L. casei and A. naeslundii were almost eliminated following 60s of ozone treatment. This killing was reduced in the presence of saliva although increasing the ozone application time to 60s overcame these reductants in saliva. Detection of altered salivary proteins indicates that saliva components constitute additional targets for ozone.


Assuntos
Antibacterianos/farmacologia , Cárie Dentária/microbiologia , Bactérias Gram-Positivas/efeitos dos fármacos , Oxidantes Fotoquímicos/farmacologia , Ozônio/farmacologia , Actinomyces/efeitos dos fármacos , Soluções Tampão , Contagem de Colônia Microbiana , Eletroforese em Gel de Poliacrilamida , Humanos , Lacticaseibacillus casei/efeitos dos fármacos , Saliva/microbiologia , Proteínas e Peptídeos Salivares/análise , Proteínas e Peptídeos Salivares/efeitos dos fármacos , Coloração pela Prata , Cloreto de Sódio , Streptococcus mutans/efeitos dos fármacos , Fatores de Tempo
5.
Clin Oral Investig ; 10(3): 175-80, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16642391

RESUMO

In this in vivo study, the proportions of mutans streptococci and lactobacilli in plaque were examined (1) on proximal surfaces of bonded, leucite-reinforced ceramic crowns and (2) on class V restorations of calcium aluminate cement (CAC). The examined proportions were intraindividually compared with those of resin composite and enamel. Mutans streptococci and lactobacilli in samples from plaque that was accumulated for 10 days on the following surfaces were determined by cultivation on blood agar plates and species-selective plates: (1) proximal leucite-reinforced ceramic crown, class II composite and enamel (n=11); and (2) class V restoration of CAC and composite, and enamel (n=17). Mutans streptococci and lactobacilli in the samples were distributed in three groups: 0, >0-1, and >1% of total bacteria. The surfaces with detected mutans streptococci were similarly distributed between the materials and enamel. The highest proportion of mutans streptococci and lactobacilli were observed on ceramic followed by composite and enamel. A higher proportion of lactobacilli, but not of mutans streptococci, was detected on enamel compared to CAC and composite. However, no significant differences were found between the surfaces. Conclusively, the materials investigated did not show different relative proportions of mutans streptococci and lactobacilli in plaque, compared to enamel.


Assuntos
Coroas/microbiologia , Placa Dentária/microbiologia , Lactobacillus/crescimento & desenvolvimento , Streptococcus mutans/crescimento & desenvolvimento , Adulto , Idoso , Idoso de 80 Anos ou mais , Compostos de Alumínio , Silicatos de Alumínio , Compostos de Cálcio , Contagem de Colônia Microbiana , Resinas Compostas , Cimentos Dentários , Esmalte Dentário/microbiologia , Porcelana Dentária , Restauração Dentária Permanente , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estatísticas não Paramétricas
6.
Caries Res ; 39(3): 201-6, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15914982

RESUMO

The aim of this in vivo study was to evaluate the neutralizing capacity, registered as change of plaque acidogenicity, on aged proximal restorations of an ion-releasing composite resin (IRCR), which releases hydroxyl, calcium, and fluoride ions at low pH. Twenty patients, with a mean age of 63 years (range 43-85), participated. All had one aged proximal IRCR restoration (mean age 15 months) and one nonrestored enamel surface to make an intraindividual comparison possible. The neutralizing effect of the IRCR was evaluated by measuring plaque pH, using the microtouch method, after a mouthrinse with 10% sucrose. The plaque pH measurements were repeated 1.5 years later on the IRCR (mean age 34 months), the enamel surfaces and a universal hybrid composite resin (CR). At both 15 and 34 months, the plaque on the IRCR surfaces showed the least acidogenic potential for the whole 60-min time interval. The largest differences between the IRCR, CR and enamel were found during the first 15 min. At 15 months, the total areas under the plaque pH curve (AUC(5.7) and AUC(6.2)) differed significantly between the IRCR and enamel surfaces for the time periods 0-5 min and 5-15 min. At 34 months, significant differences were found between IRCR and CR at the 0- to 5-min time period. It can be concluded that IRCR restorations countered the plaque pH fall and maintained it at levels where less enamel and dentin demineralization can occur.


Assuntos
Resinas Acrílicas/química , Resinas Compostas/química , Placa Dentária/química , Poliuretanos/química , Adulto , Idoso , Idoso de 80 Anos ou mais , Área Sob a Curva , Cariostáticos/farmacologia , Restauração Dentária Permanente , Feminino , Humanos , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Hidróxidos/farmacologia , Masculino , Pessoa de Meia-Idade
7.
Clin Oral Investig ; 9(2): 77-83, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15815923

RESUMO

The aim of this study was to evaluate in vivo the interfacial adaptation of class II resin composite restorations with and without a flowable liner. In 24 premolars scheduled to be extracted after 1 month, 48 box-shaped, enamel-bordered class II cavities were prepared and restored with a flowable liner (FRC, Tetric Flow/Tetric Ceram/Syntac Single-Component) or without (TRC), cured with three different curing modes: soft start and 500- or 700-mW/cm2 continuous irradiation. Interfacial adaptation was evaluated by quantitative scanning electron microscopic analysis using replica method. Gap-free adaptation in the cervical enamel (CE) was observed for FRC and TRC in 96.2 and 90.2%, for the dentin (D) in 63.6 and 64.9%, and for occlusal enamel (OE) in 99.7 and 99.5%, respectively. The difference between the two restorations was not statistically significant (ns). Significant better adaptation was observed for OE than CE and D (p<0.01), and for CE than D (p<0.01). Gap-free adaptation with the soft-start and 500- and 700-mW/cm2 continuous-curing modes was observed for CE: 88.7%, 92.7%, 97.9% (ns); OE: 99.8%, 98.7%, 100% (ns); and D: 64.0%, 63.9%, and 64.6% (ns), respectively. It can be concluded that neither the use of flowable resin composite liner nor the curing mode used influenced the interfacial adaptation.


Assuntos
Resinas Compostas/química , Forramento da Cavidade Dentária , Adaptação Marginal Dentária , Restauração Dentária Permanente/classificação , Adolescente , Criança , Preparo da Cavidade Dentária/classificação , Esmalte Dentário/ultraestrutura , Dentina/ultraestrutura , Humanos , Iluminação/instrumentação , Microscopia Eletrônica de Varredura , Cimentos de Resina/química , Propriedades de Superfície , Colo do Dente/ultraestrutura , Viscosidade
8.
Clin Oral Investig ; 8(3): 172-5, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-14963726

RESUMO

The aim of this in vivo study was to evaluate a skin reference electrode used with the microtouch method for measurements of intraoral pH. Registrations of plaque pH were made in ten healthy subjects before and up to 30 min after a mouth rinse with 10% sucrose. A microtouch electrode (Beetrode) was used in combination with two different half-cell reference electrodes: a skin silver-silver chloride plate or a glass capillary reference electrode. The skin electrode was placed on the subject's forearm in combination with a conductive gel. The glass capillary electrode, together with one of the test subject's fingers, was placed in a beaker with a 3 M KCl solution. High agreement between the two reference systems resulted in almost identical plaque-pH curves (r=0.97). The mean differences between the two systems at the different time points varied between -0.15 and +0.01 pH units, with an overall mean pH difference of 0.03 pH units. It can be concluded that the use of the skin reference electrode may very well replace the traditional reference electrode used in combination with a microtouch electrode for intraoral use.


Assuntos
Placa Dentária/química , Eletrodos , Adulto , Análise de Variância , Desenho de Equipamento , Feminino , Humanos , Concentração de Íons de Hidrogênio , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Pele/química
9.
Clin Oral Investig ; 8(2): 75-80, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-14661081

RESUMO

The aim of this in vivo study was to evaluate the interfacial marginal adaptation of a calcium aluminate cement, Doxadent (DD), and to compare it intra-individually with a resin composite, Tetric Ceram/Syntac Single-Component (TC/SS), in Class II cavities. Sixteen Class II box-shaped, enamel-bordered cavities were prepared in eight premolars scheduled to be extracted after 1 month's service for orthodontic reasons. The interfacial marginal adaptation (internal surfaces) of the restorations was evaluated by a quantitative scanning electron microscope analysis using a replica method. DD showed a statistically significant, lower degree of gap-free adaptation to enamel compared with TC/SS: 84% vs. 93%. To dentin, DD showed a significantly better adaptation than TC/SS: 72% vs. 49%. A high frequency of enamel fractures perpendicular to the margins was observed for the DD restorations, which may be explained by an expansion of the calcium-aluminate cement. It can be concluded that DD showed a better adaptation to dentin while TC/SS showed a better adaptation to enamel. The dimensional changes of DD have to be investigated before clinical use can be recommended.


Assuntos
Compostos de Alumínio/química , Compostos de Cálcio/química , Preparo da Cavidade Dentária/métodos , Cimentos Dentários/química , Adaptação Marginal Dentária , Adolescente , Criança , Resinas Compostas/química , Colagem Dentária , Esmalte Dentário/ultraestrutura , Restauração Dentária Permanente , Dentina/ultraestrutura , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Cimentos de Resina/química , Estatísticas não Paramétricas , Propriedades de Superfície
10.
Clin Oral Investig ; 7(1): 27-31, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12673434

RESUMO

The aim of this study was to determine the surface roughness of a novel calcium aluminate cement (CAC) intended for posterior restorations after treatment with different polishing devices in vitro. Forty-eight CAC specimens were polished with diamond burs at 15550 rpm or 27000 rpm, Sof-Lex discs, Jiffy points, Shofu silicone points, and Aaba universal polisher. Amalgam specimens were polished with Shofu silicone points and used as reference. Roughness was measured using a profilometer. The smoothest CAC surface was observed after use of the fine Sof-Lex disc (roughness average [Ra] 0.26 microm). Diamond burs at higher speed, points, and polisher gave rather similar results (Ra 0.58-0.72 microm). An increase in surface roughness could be seen from using diamond burs at lower speed (Ra 2.3 microm). Extra fine Shofu points and Sof-Lex discs as a final step reincreased surface roughness. Polished amalgam showed the smoothest surface in the study (Ra 0.17). It can be concluded that the smoothest CAC surfaces were obtained with the fine Sof-Lex discs. Different polishing points and diamond burs at higher speed, which are suitable polishing devices for posterior restorations, also gave relatively smooth surfaces.


Assuntos
Compostos de Alumínio , Compostos de Cálcio , Cimentos Dentários , Polimento Dentário/métodos , Análise de Variância , Cerâmica , Microscopia Eletrônica de Varredura , Propriedades de Superfície
11.
Eur J Oral Sci ; 109(4): 222-9, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11531067

RESUMO

The durability of restorations with extensive dentin/enamel-bonded posterior partial and complete ceramic coverages were investigated. The effect of luting with a dual-cured and a self-cured luting agent was also studied. In 110 patients, 182 ceramic coverages (IPS Empress) were placed. In 58 restorations, Syntac was used in combination with the dual-cured resin composite Variolink. In the other restorations luted with the chemically cured resin composite Bisfil 2B, 25 were bonded with Gluma, 57 with Allbond 2, and 42 with Syntac. Of the 182 ceramics, 13 (7.1%) were assessed as non-acceptable after a mean observation period of 4.9 yr (range 4.3 7.5 yr). The reasons for failure were fracture (5), lost restorations (4), secondary caries (3) and endodontic treatment (1). No significant differences in failure rate were seen between the two luting agents or between the three dentin-bonding agents. Ceramic coverages placed on non-vital teeth failed in 9.7% of cases (3/31) and on vital teeth in 6.6% (10/151). The success rate of the dentin-enamel-bonded ceramic coverages reduces the need for a traditional full-coverage therapy and/or post or pin(s) and core placement. The technique investigated showed many clinical advantages such as less destruction of healthy tissue, and avoidance of endodontic treatment and/or deep cervical placement of restoration margins.


Assuntos
Cerâmica , Colagem Dentária , Esmalte Dentário/ultraestrutura , Restauração Dentária Permanente/classificação , Dentina/ultraestrutura , Adulto , Idoso , Idoso de 80 Anos ou mais , Silicatos de Alumínio/química , Cerâmica/química , Resinas Compostas/química , Cárie Dentária/fisiopatologia , Porcelana Dentária/química , Falha de Restauração Dentária , Restauração Dentária Permanente/métodos , Adesivos Dentinários/química , Feminino , Seguimentos , Glutaral/química , Humanos , Masculino , Metacrilatos/química , Pessoa de Meia-Idade , Ácidos Polimetacrílicos/química , Cimentos de Resina/química , Tratamento do Canal Radicular , Estatística como Assunto , Estatísticas não Paramétricas , Análise de Sobrevida , Dente não Vital/fisiopatologia
12.
Clin Oral Investig ; 5(2): 96-101, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11480816

RESUMO

The aim of this study was to analyze factors influencing the failures of tunnel restorations performed with a glass cermet cement (Ketac Silver). Caries activity, lesion size, tunnel cavity opening size, partial or total tunnel, composite lamination or operating time showed no significant correlation to failure rate. Twelve dentists in eight clinics clinically experienced and familiar with the tunnel technique placed 374 restorations. The occlusal sections of fifty percent of the restorations were laminated with hybrid resin composite. The results of the yearly clinical and radiographic evaluations over the course of 3 years were correlated to factors that could influence the failure rate using logistic regression analysis. At the 3-year recall a cumulative number of 305 restorations were available. The cumulative replacement rate was 20%. The main reasons for replacement were marginal ridge fracture (14%) and dentin caries (3%). Another 7% of the restorations which had not been replaced were classified as failures because of untreated dentin caries. The only significant variable observed was the individual failure rate of the participating dentists varying between 9 and 50% (p=0.013).


Assuntos
Cimentos Cermet/química , Falha de Restauração Dentária , Restauração Dentária Permanente/classificação , Adolescente , Adulto , Dente Pré-Molar , Criança , Resinas Compostas/química , Cárie Dentária/terapia , Suscetibilidade à Cárie Dentária , Preparo da Cavidade Dentária/classificação , Restauração Dentária Permanente/métodos , Dentina/patologia , Feminino , Seguimentos , Humanos , Modelos Logísticos , Masculino , Dente Molar , Radiografia , Recidiva , Retratamento , Propriedades de Superfície , Fatores de Tempo , Dente/diagnóstico por imagem
13.
J Adhes Dent ; 3(1): 65-70, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11317385

RESUMO

PURPOSE: The aim of this study was to evaluate the durability of new hybrid tooth-colored restorative materials in Class III cavities. MATERIALS AND METHODS: 154 large-sized Class III restorations were placed in 50 patients. The patients received one of each of the three following materials: a resin composite (RC, Pekafill), a polyacid-modified resin composite (PMRC, Dyract) (compomer), and a resin-modified glass-ionomer cement (RMGIC, Fuji II LC). The restorations were evaluated yearly with slightly modified USPHS criteria. RESULTS: Of 141 restorations evaluated at 6 years, 16 were estimated as unacceptable. Seven of these were replaced: 2 fractures, 3 recurrent caries, and 2 due to unacceptable color match. In 9 other restorations with unacceptable color match, the patients did not request replacements. No significant differences were seen between the materials concerning the occurrence of recurrent caries. The RC showed significantly better color match. Significantly higher surface roughness was seen for the aged RMGIC restorations. Fracture of the incisal enamel corner was observed contiguous to ten restorations in the 6-year evaluation. None of the restorative techniques resulted in postoperative sensitivity or loss of vitality. CONCLUSION: The resin composite showed the best durability.


Assuntos
Preparo da Cavidade Dentária/classificação , Materiais Dentários/química , Restauração Dentária Permanente/classificação , Análise de Variância , Cor , Compômeros/química , Resinas Compostas/química , Cárie Dentária/etiologia , Esmalte Dentário/lesões , Adaptação Marginal Dentária , Falha de Restauração Dentária , Seguimentos , Cimentos de Ionômeros de Vidro/química , Humanos , Teste de Materiais , Metacrilatos/química , Recidiva , Cimentos de Resina/química , Resinas Sintéticas/química , Retratamento , Silicatos/química , Estatística como Assunto , Propriedades de Superfície , Fraturas dos Dentes/etiologia
14.
Appl Environ Microbiol ; 67(5): 2123-8, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11319090

RESUMO

Most yeast species can ferment sugars to ethanol, but only a few can grow in the complete absence of oxygen. Oxygen availability might, therefore, be a key parameter in spoilage of food caused by fermentative yeasts. In this study, the oxygen requirement and regulation of alcoholic fermentation were studied in batch cultures of the spoilage yeast Zygosaccharomyces bailii at a constant pH, pH 3.0. In aerobic, glucose-grown cultures, Z. bailii exhibited aerobic alcoholic fermentation similar to that of Saccharomyces cerevisiae and other Crabtree-positive yeasts. In anaerobic fermentor cultures grown on a synthetic medium supplemented with glucose, Tween 80, and ergosterol, S. cerevisiae exhibited rapid exponential growth. Growth of Z. bailii under these conditions was extremely slow and linear. These linear growth kinetics indicate that cell proliferation of Z. bailii in the anaerobic fermentors was limited by a constant, low rate of oxygen leakage into the system. Similar results were obtained with the facultatively fermentative yeast Candida utilis. When the same experimental setup was used for anaerobic cultivation, in complex YPD medium, Z. bailii exhibited exponential growth and vigorous fermentation, indicating that a nutritional requirement for anaerobic growth was met by complex-medium components. Our results demonstrate that restriction of oxygen entry into foods and beverages, which are rich in nutrients, is not a promising strategy for preventing growth and gas formation by Z. bailii. In contrast to the growth of Z. bailii, anaerobic growth of S. cerevisiae on complex YPD medium was much slower than growth in synthetic medium, which probably reflected the superior tolerance of the former yeast to organic acids at low pH.


Assuntos
Oxigênio/metabolismo , Zygosaccharomyces/crescimento & desenvolvimento , Aerobiose , Anaerobiose , Meios de Cultura/química , Etanol , Fermentação , Conservação de Alimentos/métodos , Zygosaccharomyces/efeitos dos fármacos
15.
Antonie Van Leeuwenhoek ; 80(1): 11-7, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11761363

RESUMO

Human acylphosphatase (h-AP, EC 3.6.1.7) has been reported to catalyse the hydrolysis of the 1-phosphate group of 1,3-diphosphoglycerate. In vivo operation of this reaction in the yeast Saccharomyces cerevisiae would bypass phosphoglycerate kinase and thus reduce the ATP yield from glycolysis. To investigate whether h-AP can indeed replace the S. cerevisiae phosphoglycerate kinase, a multi-copy plasmid carrying the h-AP gene under control of the yeast TDH3 promoter was introduced into a pgk1 delta mutant of S. cerevisiae. A strain carrying the expression vector without the h-AP cassette was used as a reference. For both strains, steady-state carbon- and energy-limited chemostat cultures were obtained at a dilution rate of 0.10 h(-1) on a medium containing a mixture of glucose and ethanol (15% and 85% on a carbon basis, respectively). Although the h-AP strain exhibited a high acylphosphatase activity in cell extracts, switching to glucose as sole carbon and energy source resulted in a complete arrest of glucose consumption and growth. The lack of a functional glycolytic pathway was further evident from the absence of ethanol formation in the presence of excess glucose in the culture. As h-AP cannot replace yeast phosphoglycerate kinase in vivo, the enzyme is not a useful tool to modify the ATP yield of glycolysis in S. cerevisiae.


Assuntos
Hidrolases Anidrido Ácido/genética , Hidrolases Anidrido Ácido/metabolismo , Fosfoglicerato Quinase/metabolismo , Saccharomyces cerevisiae/enzimologia , Trifosfato de Adenosina/metabolismo , Meios de Cultura , Glicólise , Humanos , Mutação , Fosfoglicerato Quinase/genética , Plasmídeos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Transformação Genética , Acilfosfatase
16.
J Bacteriol ; 182(24): 7007-13, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11092862

RESUMO

The Saccharomyces cerevisiae ICL1 gene encodes isocitrate lyase, an essential enzyme for growth on ethanol and acetate. Previous studies have demonstrated that the highly homologous ICL2 gene (YPR006c) is transcribed during the growth of wild-type cells on ethanol. However, even when multiple copies are introduced, ICL2 cannot complement the growth defect of icl1 null mutants. It has therefore been suggested that ICL2 encodes a nonsense mRNA or nonfunctional protein. In the methylcitrate cycle of propionyl-coenzyme A metabolism, 2-methylisocitrate is converted to succinate and pyruvate, a reaction similar to that catalyzed by isocitrate lyase. To investigate whether ICL2 encodes a specific 2-methylisocitrate lyase, isocitrate lyase and 2-methylisocitrate lyase activities were assayed in cell extracts of wild-type S. cerevisiae and of isogenic icl1, icl2, and icl1 icl2 null mutants. Isocitrate lyase activity was absent in icl1 and icl1 icl2 null mutants, whereas in contrast, 2-methylisocitrate lyase activity was detected in the wild type and single icl mutants but not in the icl1 icl2 mutant. This demonstrated that ICL2 encodes a specific 2-methylisocitrate lyase and that the ICL1-encoded isocitrate lyase exhibits a low but significant activity with 2-methylisocitrate. Subcellular fractionation studies and experiments with an ICL2-green fluorescent protein fusion demonstrated that the ICL2-encoded 2-methylisocitrate lyase is located in the mitochondrial matrix. Similar to that of ICL1, transcription of ICL2 is subject to glucose catabolite repression. In glucose-limited cultures, growth with threonine as a nitrogen source resulted in a ca. threefold induction of ICL2 mRNA levels and of 2-methylisocitrate lyase activity in cell extracts relative to cultures grown with ammonia as the nitrogen source. This is consistent with an involvement of the 2-methylcitrate cycle in threonine catabolism.


Assuntos
Acil Coenzima A/metabolismo , Carbono-Carbono Liases/genética , Carbono-Carbono Liases/metabolismo , Isocitrato Liase/genética , Isocitrato Liase/metabolismo , Mitocôndrias/enzimologia , Saccharomyces cerevisiae/enzimologia , Meios de Cultura , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Glucose/farmacologia , Saccharomyces cerevisiae/genética , Análise de Sequência de DNA , Frações Subcelulares , Treonina/farmacologia
17.
J Bacteriol ; 182(17): 4730-7, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10940011

RESUMO

NDI1 is the unique gene encoding the internal mitochondrial NADH dehydrogenase of Saccharomyces cerevisiae. The enzyme catalyzes the transfer of electrons from intramitochondrial NADH to ubiquinone. Surprisingly, NDI1 is not essential for respiratory growth. Here we demonstrate that this is due to in vivo activity of an ethanol-acetaldehyde redox shuttle, which transfers the redox equivalents from the mitochondria to the cytosol. Cytosolic NADH can be oxidized by the external NADH dehydrogenases. Deletion of ADH3, encoding mitochondrial alcohol dehydrogenase, did not affect respiratory growth in aerobic, glucose-limited chemostat cultures. Also, an ndi1Delta mutant was capable of respiratory growth under these conditions. However, when both ADH3 and NDI1 were deleted, metabolism became respirofermentative, indicating that the ethanol-acetaldehyde shuttle is essential for respiratory growth of the ndi1 delta mutant. In anaerobic batch cultures, the maximum specific growth rate of the adh3 delta mutant (0.22 h(-1)) was substantially reduced compared to that of the wild-type strain (0.33 h(-1)). This is consistent with the hypothesis that the ethanol-acetaldehyde shuttle is also involved in maintenance of the mitochondrial redox balance under anaerobic conditions. Finally, it is shown that another mitochondrial alcohol dehydrogenase is active in the adh3 delta ndi1 delta mutant, contributing to residual redox-shuttle activity in this strain.


Assuntos
Acetaldeído/metabolismo , Álcool Desidrogenase/metabolismo , Etanol/metabolismo , Mitocôndrias/enzimologia , NADH Desidrogenase/metabolismo , Saccharomyces cerevisiae/enzimologia , Álcool Desidrogenase/genética , Anaerobiose , Meios de Cultura/metabolismo , Deleção de Genes , Glucose/metabolismo , NAD/metabolismo , NADH Desidrogenase/genética , Oxirredução , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo
18.
Acta Odontol Scand ; 58(2): 77-84, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10894429

RESUMO

The aim of this in vivo study was to evaluate the interfacial adaptation of Class II resin composite open sandwich restorations with a polyacid-modified resin composite as a stress-absorbing layer (PMRC/RC). Twenty Class II box-shaped, enamel-bordered cavities were prepared in 10 premolars scheduled to be extracted for orthodontic reasons. An open PMRC/RC sandwich restoration was placed in 1 of the cavities of each tooth. The first layer, PMRC, in the proximal box extended to the periphery in the cervical part of the cavity. The following RC layers were placed with a horizontally incremental technique. The PMRC was excluded from the control cavity. The teeth were extracted after 1 month and the interfacial adaptation of the restorations was studied with quantitative scanning electron microscope analysis using a replicate technique. Gap-free interfacial adaptation was observed for the PMRC/RC and RC restorations in cervical enamel in 97% and 73%, respectively (P = 0.006). The gap-free scores for dentin were 87% and 64%, respectively (P = 0.022). Excellent interfacial adaptation was observed in both groups for the occlusal enamel 99% and 100%, respectively. The adaptation to occlusal enamel for the direct resin composite restorations was significantly better than to dentin or cervical enamel. A higher frequency of enamel fractures was observed parallel to the cervical margins compared to the occlusal. No dentin fractures were observed in the experimental groups. The PMRC/RC sandwich technique showed a statistically significant improved interfacial adaptation to dentin and cervical enamel in Class II enamel-bordered cavities. The clinical significance of the differences has to be evaluated.


Assuntos
Compômeros/química , Resinas Compostas/química , Adaptação Marginal Dentária , Restauração Dentária Permanente/classificação , Absorção , Dente Pré-Molar , Colagem Dentária , Preparo da Cavidade Dentária/classificação , Esmalte Dentário/lesões , Esmalte Dentário/ultraestrutura , Restauração Dentária Permanente/métodos , Dentina/ultraestrutura , Humanos , Microscopia Eletrônica de Varredura , Técnicas de Réplica , Estresse Mecânico , Propriedades de Superfície , Colo do Dente/ultraestrutura , Fraturas dos Dentes/etiologia
19.
Dent Mater ; 16(4): 285-91, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10831784

RESUMO

OBJECTIVES: The purpose of this study was to evaluate the clinical retention of three new adhesive systems in non-carious cervical lesions during a 3-year period. METHODS: The adhesive systems, a three-step (EBS/Pertac Hybrid), a one-bottle resin bonding agent (One-Step/Pertac Hybrid) and a resin-modified glass ionomer cement (Fuji II LC) were placed in 148 non-carious cervical lesions, 87 with sclerotic dentin and 61 non-sclerotic. Of the sclerotic lesions treated with the two resin bonding systems, 37 were slightly roughened with a diamond bur before conditioning. The restorations were evaluated every 6 months during a 3-year period. RESULTS: All except six restorations were evaluated during the 3 years. The cumulative loss rates for EBS, One-Step and Fuji II LC were, at 1 year: 2, 24 and 2% and at 3 years: 10, 49, 7%, respectively. The one-bottle adhesive showed significantly more failures. The five lost EBS restorations were found in non-sclerotic lesions, while the three lost Fuji II LC restorations had been placed in sclerotic lesions. For the One-Step material the loss frequency for non-sclerotic versus sclerotic lesions was 31.8 and 65.2%, respectively. Slight roughening of the sclerotic dentin surfaces with a diamond bur did not increase retention of the restorations. SIGNIFICANCE: The three-step resin adhesive and the RMGIC showed clinically acceptable retention rates, while a high failure rate was registered for the one-bottle adhesive.


Assuntos
Colagem Dentária , Preparo da Cavidade Dentária/classificação , Adesivos Dentinários/química , Dentina/patologia , Colo do Dente/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Bis-Fenol A-Glicidil Metacrilato/química , Distribuição de Qui-Quadrado , Cor , Resinas Compostas/química , Adaptação Marginal Dentária , Falha de Restauração Dentária , Restauração Dentária Permanente/métodos , Dentina Secundária/patologia , Feminino , Seguimentos , Cimentos de Ionômeros de Vidro/química , Humanos , Masculino , Metacrilatos/química , Pessoa de Meia-Idade , Ácidos Fosfóricos/química , Cimentos de Resina/química , Resinas Sintéticas/química , Propriedades de Superfície , Doenças Dentárias/terapia
20.
Eur J Oral Sci ; 108(3): 239-46, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10872995

RESUMO

The purpose of this study was to evaluate Cerec CAD/CAM inlays processed of two industrially made machinable ceramics during an 8-yr follow-up period. Each of 16 patients received two similar ceramic inlays. Half the number of the inlays were made of a feldspathic (Vita Mark II) and the other of a glass ceramic (Dicor MGC) block. The inlays were luted with a dual resin composite and evaluated clinically using modified USPHS criteria at baseline, 8 months, 2, 3, 5, 6 and 8 yr, and indirectly using models. At baseline, 84% of the inlays were estimated as optimal and 16% as acceptable. Postoperative sensitivity was reported by one patient for 8 months. Of the 32 inlays evaluated during the 8 yr, 3 failed due to fracture of the material. No secondary caries was found adjacent to the inlays. No significant differences in the clinical performance were found between inlays made of the two ceramics. It can be concluded that the CAD/CAM inlays processed of the two ceramics functioned well during the 8-yr follow-up period.


Assuntos
Desenho Assistido por Computador , Porcelana Dentária , Planejamento de Prótese Dentária , Restaurações Intracoronárias , Adulto , Análise de Variância , Cerâmica , Feminino , Seguimentos , Temperatura Alta , Humanos , Masculino , Pessoa de Meia-Idade , Cimentos de Resina , Resultado do Tratamento
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