# Effect of Crown to Titanium Base Ratio and Force Angle on the Biomechanical Behavior of Dental Implants With CAD/CAM Zirconia and Lithium Disilicate Crowns: A Finite Element Analysis

## TL;DR

This study uses computer modeling to show how the height of a dental implant base and crown, along with the angle of force, affects stress in dental implants and surrounding bone.

## Contribution

The study introduces a finite element analysis to evaluate the biomechanical impact of varying crown and abutment heights and loading angles in anterior dental implants.

## Key findings

- A 3.5 mm Ti-base with an 8 mm monolithic zirconia crown produced the lowest stress in the crown and abutment.
- Longer crowns (11 mm) increased crown stress, and abutment height effects depend on material and loading angle.
- Oblique loading (45°) increased bone stress compared to 65°, highlighting the importance of axial force transmission.

## Abstract

This study investigates how titanium‐base (Ti‐base) abutment height, crown design, and force angulation affect biomechanics in an anterior single‐implant restoration, using finite element analysis.

A three‐dimensional anterior maxilla model was constructed with linear elastic properties. Two Ti‐base heights (3.5, 5.5 mm) and two crown heights (8, 11 mm) were tested as monolithic zirconia or bilayer (zirconia core veneered with lithium disilicate). A 146 N load was applied at the cingulum at 45° or 65°. von Mises stress (VMS) was computed in the crown, abutment, and surrounding bone.

A 3.5 mm Ti‐base with an 8 mm monolithic zirconia crown (SSZ) produced the lowest crown and abutment VMS. The highest crown VMS occurred in the 11 mm bilayer crown on a 5.5 mm Ti‐base (LLZEX) at 45°, while the highest abutment VMS occurred in the 3.5 mm Ti‐base with an 8 mm bilayer crown (SSZEX) at 65°. An increase in crown height raises crown stresses, whereas the impact of abutment height depends on configuration and angle. In bone, 45° loading increased VMS compared with 65° across all models.

In anterior single‐implant models, the lowest restoration stresses were achieved with a short crown on a 3.5‐mm Ti‐base and monolithic zirconia. Long crowns (11 mm) increased crown stresses, and abutment height should be tailored to material and anticipated loading direction rather than adjusted by a single rule. Oblique loading consistently raised bone stress compared with 65°, underscoring the need to optimize for axial force transmission.