Does the index in Morse taper connection affect the abutment stability? An in vitro experimental study

Abstract

The present study compared three different implant and abutment sets of type Morse taper (MT) connection, with- and without-index, were analyzed regarding their mechanical behavior without and with cyclic load application simulating the masticatory function. Ninety implant and abutment (IA) sets were used in the present study, divided into three groups (n = 30 samples per group): Group A, Ideale solid straight abutment (one piece) without index; Group B, Ideale abutment with an angle of 30-degree (two pieces) without index; Group C, Ideale abutment with an angle of 30-degree (two pieces) with index. The abutment stability quotient (ASQ) values, detorque value and rotation angle were measured before and after the cycling load. Twenty IA sets of each group were submitted to mechanical load at 360,000 cycles. The ASQ without load were 64.7 ± 2.49 for the group A, 60.2 ± 2.64 for the group B, 54.4 ± 3.27 for the group C; With load were 66.1 ± 5.20 for the group A, 58.5 ± 6.14 for the group B, 58.9 ± 2.99 for the group C. Detorque values were lower in groups B and C compared to group A (p < 0.05). In conclusion, the presence of the index did not influence the stability values. However, solid straight abutments (group A) showed higher values of stability compared to groups of angled abutments (groups B and C).

Fig 1. Representative image of the implant and abutments used.

Fig 2. Image demonstrating the dimensions in the main parts of the abutment.

Fig 3

(a) Image of the block made to support the IA sets during the test; (b) the arrows indicating the cutting of the two edges in each block with an angle of 30 ± 2 degrees; (c) representative image of the drilling moment with the base-table angled at 30 degrees to obtain the desired inclination of the implant; (d) arrow indicating the implant installation driver and its inclination; (e) arrow showing the implant positioned inside the block at the level of its platform.

Fig 4. Schematic image to show the positioning of the implants in the blocks and the direction of the loads applied to the samples of the three groups.

Fig 5

Representative image of the IA set, and the magnetic sensor installed (a). ASQ measurement in the frontal direction (b) and in lateral direction (c).

Fig 6. Box plot graphs shows the data values obtained for the abutment stability quotient (ASQ) at the three groups without- and with-load.

Fig 7. Bar graphs showing the distribution of data obtained after calculating the difference between the applied torque and the obtained torque value, with and without load application.

Fig 8. Bar graphs presenting the data distribution of the angle rotation obtained in each group, without and with load application.