title: Influence of methodologic aspects on the results of implant-abutment interface microleakage tests: a critical review of in vitro studies.
abstract: OBJECTIVE
  This study sought to evaluate the influence of methodologic aspects on variations in the findings of in vitro microleakage studies of the implant-abutment interface.
  
  
  METHODS
  The MEDLINE, EMBASE, and Cochrane Library databases were consulted for in vitro studies published between 1990 and August 2011. Date from the studies that met the inclusion and exclusion criteria were arranged in tables and subjected to descriptive analysis.
  
  
  RESULTS
  Twenty-one studies were found to be eligible for the analysis after application of the inclusion/exclusion criteria. Sixteen studies used bacteria (76.2%), one used a bacterial toxin (4.76%), one used saliva (4.76%), two employed dyes (9.52%), and one used a combination of dyes and bacteria (4.76%). Eight studies evaluated microleakage from the inner portion of the implant to the external portion (38.1%) and nine examined the reverse (42.85%), while four studies investigated the relationship between them (19.05%). The volume inoculated inside the implants ranged from 0.1 to 5.0 mL. The bacterial concentrations used in the tests ranged from 2.41 x 10⁶ to 8 x 10⁸ colony-forming units/mL. Oral bacterial flora; mixtures of bacteria, toluidine blue, and gentian violet; and lipopolysaccharide of Salmonella enterica bacterial toxins were used. The monitoring period of test results ranged from 24 hours to 11 weeks for bacteria, 5 minutes to 7 days for dye, and 7 days for bacterial toxins. In four studies, microleakage was correlated with the size of the implant-abutment microgap. The external-hexagon implant configuration showed the greatest microleakage, followed by internal-trilobe, internal-hexagon, and internal-taper configurations.
  
  
  CONCLUSIONS
  The lack of standardization hinderd comparisons of the studies and could explain the divergent results. It is suggested for future studies that special emphasis be placed upon inoculation and analysis of the specific volume for each system, lower concentrations of inoculated bacterial suspensions, and shorter follow-up time when using bacteria.
authors: Department of Occlusion, Fixed Prostheses, and Dental Materials, Federal University of Uberlândia, School of Dentistry, Uberlândia, Brazil.
authors: João Paulo
authors: JP
authors: da Silva-Neto
authors: Mauro Antônio de Arruda
authors: MA
authors: Nóbilo
authors: Mário Paulo Amante
authors: MP
authors: Penatti
authors: Paulo Cézar
authors: PC
authors: Simamoto
authors: Flávio Domingues
authors: FD
authors: das Neves
mesh_terms: D058491:Bacterial Load / Q000379:methods; D004396:Coloring Agents; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D015921:Dental Implants / Q000382:microbiology; D003763:Dental Leakage / Q000175:diagnosis* / Q000382:microbiology; D005840:Gentian Violet; D006801:Humans; D011135:Polysaccharides, Bacterial; D012463:Saliva; D019779:Salmonella enterica; D013997:Time Factors; D014048:Tolonium Chloride
chemical_list: D004396:Coloring Agents; D015921:Dental Implants; D011135:Polysaccharides, Bacterial; D014048:Tolonium Chloride; D005840:Gentian Violet