Assessment of the stresses produced on the bone implant/tissue interface to the different insertion angulations of the implant - a three-dimensional analysis by the finite elements method

Abstract

Background: The present study aimed to assess the stresses produced on the surface of the bone tissue around dental implants with three different insertion angulations subjected to axial and oblique loading.

Material and methods: The study was created according to the recommendations of the Checklist for Reporting In-vitro Studies (CRIS). The Straumann™ bone level RC (4.1 x 10 mm) implant, Cone Morse connection (CM), RC Straumann Variobase™ with abutment (3.5 mm) was placed in the region of element 16, with the platform positioned at the height of the bone crest. Three assessment models were produced: model M1 or control - implant perpendicular to the bone crest; model M2 - implant angulated at 17° relative to the bone crest; and model M3 - implant angulated at 30° relative to the bone crest. The masticatory loads were simulated with 100 N of intensity and two loading patterns (axial and oblique) were applied to each model. Then, the models were exported to the finite elements simulation software Ansys Workbench V19.2 (Ansys Inc., Canonsburg, PA, USA). To assess the finite elements, qualitative and quantitative analyses were performed.

Results: It was observed that, under axial loading, qualitatively, the peaks occurred in the cavosurface region, palatal aspect in M1 and M2, and buccal aspect in M3. Quantitatively, the greatest angulation resulted in a low stress peak. Under oblique loading, qualitatively, the peaks occurred in the cavosurface region, buccal aspect in the three groups. Quantitatively, the greatest angulation of the implant resulted in an increase in stress peaks on the buccal aspect.

Conclusions: Under axial loading, the three insertion angulations of the implant - M1, M2, and M3 - were clinically viable. When subjected to oblique loading, the 30° angulation (M3) suggested a significant risk of bone loss and it was contraindicated. Key words:Finite element analysis, dental implants, load support.

Figure 1

Models analyzed with different angulations relative to the bone crest. M1 (perpendicular); M2 (17°); M3 (30°).

Figure 2

Formula.

Figure 3

Peri-implant cortical bone insertion in the different models, highlighted in green. M1: perpendicular to the bone crest; M2: inclination of 17°; and M3: inclination of 30°.

Figure 4

External sectioned view of the results in the peri-implant bone under axial loading. A linear color scale was used, where blue indicates low values and red indicates high values of stress on the peri-implant bone. Models: M1, M2, and M3. VO view: buccal occlusal; MS: sectioned mesial. Considering the view is sectioned, the mesial view shows the distal portion.

Figure 5

External sectioned view of the results in the peri-implant bone under oblique loading. A linear color scale was used, where blue indicates low values and red indicates high values of stress on the peri-implant bone. Models: M1, M2, and M3. PO view: palatal occlusal; DS: sectioned distal. Considering the view is sectioned, the distal view shows the mesial portion.