Micro-leakage at the implant-abutment interface with different tightening torques in vitro

Abstract

ObjectivesThis study evaluated the microleakage at the implant/abutment interface of external hexagon (EH) implants and abutments with different amounts of bacteria and tightening torques. Material and MethodsA 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). ResultsDuring 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. ConclusionAfter 14 days of experimentation, the bacteria were proven to remain viable inside the implant internal cavity.

Bacterial microleakage at the implant-abutment interface in Morse taper implants

“…These volumes may also lead to low levels of bacterial suspension in relation to the I-A interface, hindering the microleakage 15 and showing negative results for microleakage as in previous studies 7,16 . These results reinforce the theory that high concentrations of bacteria and reduced volumes may mask the microleakage [14][15] . Moreover, it may lead to false negative results caused by bacterial death inside the implants.…”

“…In order to avoid this, beyond the precautions on the concentration of bacterial suspension, bacterial viability was confirmed after the follow up period by disassembling the specimens that presented negative results for microleakage. Precaution involving the concentration of bacterial suspensions is already a reality; 4,5,14 but confirmation of bacterial viability was made only in two studies 5,14 . The chosen post-inoculation control test was immersion of the implants up to the I-A interface coating for 30 s. The overflow control by immersion was used in a previous study and showed good results 9 .…”

“…Escherichia coli strain ATCC 35218 was selected for bacterial microleakage evaluation because it is a facultative anaerobic bacterium, able to survive in adverse situations and has a good motility, and has been used in other in vitro tests 2,5,7,[13][14] . This bacterium was cultivated in brain heart infusion broth -BHI (Biolife, Milano, Italy) for 24 h in an incubator at 37 °C (Biomatic, Porto Alegre, RS, Brazil).…”

“…The implants were set on a holder and an automatic pipette (0.1-20 µL, Labmate+ HT; PZ HTL S.A, Warsaw, Poland) was fixed to the vertical shaft of a prosthetic surveyor (BIOART, São Carlos, SP, Brazil.) 14 .…”

“…Two-piece implants have a microgap depending on the interface type or system, but presence of fluid flow at this interface and its relationships are very variable [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] . This has been correlated to the presence of bacterial infiltration and inflammatory cells that may lead to bone loss around this area 19 .…”