RESUMO
Gram-negative bacteria predominantly use two types of quorum sensing (QS) systems--LuxI-LuxR, responsible for synthesis of N-acylhomoserine lactones (AHL or AI-1 signal molecule), and LuxS, which makes furanones (AI-2 signal molecule). We showed that LuxS and two LuxI-LuxR (YtbIR and YpsIR) systems are functional in Y. pestis. Four different AHL molecules were detected in Y. pestis extracts using TLC bioassays. Our data suggest that YtbIR is responsible for the production of long chain AHLs. Confocal laser scanning microscopy showed that biofilm formation is decreased in an ytbIR ypsIR luxS mutant. Two-dimensional gel electrophoresis revealed altered levels of protein expression in a Y. pestis triple QS mutant at 26 degrees C and 37 degrees C.
Assuntos
Percepção de Quorum/genética , Percepção de Quorum/fisiologia , Yersinia pestis/genética , Yersinia pestis/fisiologia , Acil-Butirolactonas/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Sequência de Bases , Biofilmes/crescimento & desenvolvimento , Liases de Carbono-Enxofre/genética , Liases de Carbono-Enxofre/fisiologia , Primers do DNA/genética , DNA Bacteriano/genética , Expressão Gênica , Genes Bacterianos , Genes Reporter , Homosserina/análogos & derivados , Homosserina/biossíntese , Óperon Lac , Lactonas , Plasmídeos/genéticaRESUMO
BACKGROUND: The purpose of this clinical study is to evaluate the radiographic bone remodeling, survival rate, and soft tissue health surrounding a variable-thread tapered implant immediately placed in extraction sites. METHODS: Sixty implants were placed in 55 patients at six centers according to a predetermined protocol. All implants were placed in extraction sockets and were subjected to immediate temporization and function. Definitive prostheses (58 single crowns and one two-unit fixed bridge) were placed within the first year. Clinical and radiographic examinations were performed at implant placement and after 3, 6, 12, 24, and 36 months. Measurements of implant stability, papilla index, plaque, peri-implant mucosa, and marginal bone levels were recorded at each visit. RESULTS: Thirty-five implants were evaluated at both implant insertion and 3-year follow-up. Bone levels were observed at 6 months after surgery and yearly intervals thereafter and remained stable throughout the study. There was a slight decrease in mean bone level from -0.68 mm at implant insertion to -0.93 mm at the 6-month recall and then an increase of bone to -0.53 mm from the reference point at the 2-year follow-up (an average increase of 0.15 mm from implant insertion). Bone levels remained steady between the 2-year recall and the 3-year recall. Papilla scores increased significantly (P <0.001; Wilcoxon signed-rank test) from insertion to the 3-year follow-up, with most of the increase occurring during the first year. Patient assessments of function, esthetics, feel of implant, speech, and self-esteem also showed significant improvement over the course of the study. CONCLUSIONS: The results, over 36 months, indicate that the variable-thread tapered implant can be used safely and effectively under demanding conditions as an immediate postextraction tooth replacement. Bone remodeling remained stable with a slight increase, and patients expressed high levels of satisfaction with the restorative results over the course of the study.
Assuntos
Implantes Dentários , Planejamento de Prótese Dentária , Prótese Dentária Fixada por Implante , Restauração Dentária Temporária , Carga Imediata em Implante Dentário/métodos , Alvéolo Dental/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Processo Alveolar/patologia , Remodelação Óssea/fisiologia , Coroas , Índice de Placa Dentária , Retenção em Prótese Dentária , Prótese Parcial Fixa , Estética Dentária , Feminino , Seguimentos , Gengiva/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Índice Periodontal , Estudos Prospectivos , Autoimagem , Fala/fisiologia , Adulto JovemRESUMO
PURPOSE: The purpose of this clinical trial was to evaluate the survival rate, bone remodeling, and soft tissue health surrounding variable-thread tapered implants placed in fresh extraction sites and loaded immediately. MATERIALS AND METHODS: Sixty implants were placed in 55 patients at six centers according to a predetermined protocol. All implants were placed in extraction sockets and were subjected to immediate temporization. Definitive prostheses were placed within the first year. Clinical and radiographic examinations were performed at implant placement and after 3, 6, 12, and 24 months. Assessments of implant stability, Papilla Index, plaque, peri-implant mucosa, and marginal bone levels were performed at the respective visits. RESULTS: Fifty-five patients were treated and were restored with 58 single crowns and 1 two-unit fixed partial prosthesis. The cumulative survival rate was 98.3% after 2 years. One implant failed prior to 3 months. The mean marginal bone remodeling from implant insertion to 1 year was -0.22 ± 1.30 mm (n = 41), followed by an average bone gain of 0.12 ± 0.77 mm (n = 33) between 12 and 24 months. Mean marginal bone remodeling was -0.10 ± 1.38 mm (n = 35) from implant insertion to 2 years. Papilla size increased significantly over the 2-year study period. Patient assessments of function, esthetics, and self-esteem also showed significant improvement. CONCLUSION: The 24-month results indicate that the variable-thread tapered implant can be used safely and effectively under demanding conditions as an immediate postextraction tooth replacement.