title: Micro-leakage at the implant-abutment interface with different tightening torques in vitro.
abstract: OBJECTIVE
  This study evaluated the microleakage at the implant/abutment interface of external hexagon (eH) implants and abutments with different amounts of bacteria and tightening torques.
  
  
  METHODS
  A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.5: 0.5 µL; V1.0: 1.0 µL e V1.5: 1.5 µL, and tightened to the manufacturer's recommended torque. The second phase of this experiment used 27 assemblies that were similar to those used in the first phase. These samples were inoculated with 0.5 µL of bacterial suspension and divided into three groups (n=9). T10: 10 Ncm; T20: 20 Ncm and T32: 32 Ncm. The samples were evaluated according to the turbidity of the broth every 24 hours for 14 days, and the bacteria viability was tested after that period. The statistical evaluation was conducted by Kruskal-Wallis testing (p<.05).
  
  
  RESULTS
  During the first phase, groups V1.0 and V1.5 was presented with bacterial contamination in all samples after 24 h. During the second phase, two samples from group T10 and one from T20 presented positive results for bacterial contamination. Different amounts of bacterial solution led to overflow and contamination during the first 24 h of the experiment. The tightening torques did not statistically affect the microleakage in the assemblies. However, the group that was tightened to 32 Ncm torque did not show any bacterial contamination.
  
  
  CONCLUSIONS
  After 14 days of experimentation, the bacteria were proven to remain viable inside the implant internal cavity.
authors.affiliation: Department of Fixed Prostheses, Occlusion and Dental Materials, School of Dentistry, Federal University of Uberlândia, Uberlândia, MG, Brazil.
authors.forename: João Paulo da
authors.initials: JP
authors.lastname: Silva-Neto
authors.forename: Marcel Santana
authors.initials: MS
authors.lastname: Prudente
authors.forename: Thiago de Almeida Prado Naves
authors.initials: Tde A
authors.lastname: Carneiro
authors.forename: Mauro Antônio de Arruda
authors.initials: MA
authors.lastname: Nóbilo
authors.forename: Mario Paulo Amante
authors.initials: MP
authors.lastname: Penatti
authors.forename: Flávio Domingues das
authors.initials: FD
authors.lastname: Neves
mesh_terms: D001863:Bone Screws; D000044:Dental Abutments / Q000382:microbiology*; D059605:Dental Implant-Abutment Design / Q000379:methods*; D015921:Dental Implants / Q000382:microbiology*; D003763:Dental Leakage / Q000382:microbiology*; D004926:Escherichia coli / Q000254:growth & development; D006801:Humans; D008422:Materials Testing; D018709:Statistics, Nonparametric; D013997:Time Factors; D019415:Torque
chemical_list: D015921:Dental Implants