Bacterial infiltration and detorque at the implant abutment morse taper interface after masticatory simulation

Abstract

This study evaluated the bacterial infiltration and the detorque of indexed and non-indexed abutments of Morse taper implants (MTI) after mechanical cycling (MC). 40 MTI were distributed into four groups: IIA (indexed implant abutments); NIIA (non-indexed implant abutments); IIAMC (indexed implant abutments submitted to MC); NIIAMC (non-indexed implant abutments submitted to MC), which were carried out under one million 5 Hz frequency and 3 Bar pressure. After mechanical cycling, all groups were immersed in a bacterial solution in Brain Heart Infusion Agar. After detorque, the bacteria infiltration was evaluated by counting the colony-forming units. For the bacterial infiltration, analysis was applied to the Kruskal-Wallis test (p = 0.0176) followed by Dunn's test. For the detorque analysis, the two-way repeated-measures ANOVA was applied, followed by the Tukey's test (p < 0.0001). Bacteria infiltration was highly observed in NIIA (p = 0.0027) and were absent in IIAMC and NIIAMC. The detorque values for IIA (19.96Ncm ± 0.19Ncm), NIIA (19.90Ncm ± 0.83Ncm), and NIIAMC (19.51Ncm ± 0,69Ncm) were similar and remained close to the initial value, while IIAMC (55.2Ncm ± 2.36Ncm) showed an extremely significant torque value increase (p < 0.0001). The mechanical cycling resulted in mechanical sealing of the implant-abutment interface, preventing bacterial infiltration in the indexed and non-indexed specimens, and increasing the detorque strength in the group of indexed abutments.

Figure 1

Representative scheme of the indexed Morse taper implant, with the respective indexed and non-indexed abutments, on which the 40 sets of implants and prosthetic abutments for groups IIA, NIIA, IIAMC and NIIAMC were mounted.

Figure 2

Sets of implants and abutments mounted in a laminar flow with aid of a digital torque wrench.

Figure 3

Representation of mechanical cycling in IIAMC.

Figure 4

(A) Sets of implants and abutments mounted to the syringes; (B) Syringes with the implant-abutment specimens inserted with bacterial culture medium in the test tubes.

Figure 5

(A) The removal of the syringe from the test tube using a thin swab; (B) Cleaning of the external surface of the implant-abutment set with a chlorhexidine solution at 0.12%.

Figure 6

(A) Detorque of the abutment-implant set with the digital torque wrench; (B) Sample collection from the inner side of the implant after detorque.

Figure 7

(A) Eppendorf tubes containing saline solution; (B) Bacterial solution transferred to a Petri dish with BHIA; (C) Harvesting of bacterial subculture in a Petri dish; (D) Subculture dishes in a bacterial growth chamber.

Figure 8

Statistical analysis of the detorque values of the specimens—Two-Way Repeated Measures ANOVA, followed by Tukey’s test.

Figure 9

Non-parametric analysis—Kruskal–Wallis and Dunn’s tests (α < 0,05): IIA indexed abutments and Morse taper implants, NIIA non-indexed abutments and Morse taper implants; IIAMC mechanical cycling indexed abutments and Morse taper implants, NIIAMC Mechanical cycling non-indexed abutments and Morse taper implants.