Finite Element Analysis of Dental Diamond Burs - Stress Distribution in Dental Structures During Cavity Preparation

At a Glance

Metadata	Details
Publication Date	2025-07-16
Journal	Prosthesis
Authors	K N Chethan, H.N. Abhilash, Afiya Eram, Saniya Juneja, Divya Shetty
Institutions	Manipal Academy of Higher Education
Analysis	Full AI Review Included

Executive Summary

Objective: Employed dynamic Finite Element Analysis (FEA) to quantify von Mises stress distribution in enamel, dentin, and pulp during dental cavity preparation using round diamond burs.
Methodology: Utilized a CT-derived 3D human maxillary molar model and the Cowper-Symonds material model to simulate high-strain-rate tool-tissue interaction under varying bur diameters (1, 2, 3 mm) and Depths of Cut (DOC) (1, 2 mm).
Key Finding on Stress Magnitude: Larger burs (3 mm) and deeper cuts (2 mm DOC) resulted in the highest stress levels, peaking at 140.43 MPa in dentin, significantly increasing the risk of structural damage (microcracks/fractures).
Optimal Protocol Recommendation: Clinically, the use of smaller burs (less than or equal to 2 mm) and shallower cuts (less than or equal to 1 mm DOC) is advised to minimize stress accumulation in dental structures.
Dentin’s Role: Dentin demonstrated superior stress distribution compared to brittle enamel, acting as a crucial load-bearing shock absorber, especially during deeper material removal.
Pulpal Health Concern: Although pulp stress remained low (max 1.036 MPa), the stress magnitude showed a clear increasing trend with larger burs and deeper cuts, raising concerns for cumulative damage over repeated procedures.

Technical Specifications

Parameter	Value	Unit	Context
Simulation Software	ANSYS Workbench 2024 R2	N/A	Explicit Dynamic Analysis
Dental Model Source	I-CAT 17-19 Scanner	N/A	CT data of human maxillary first molar
Bur Diameters Tested	1, 2, 3	mm	Round diamond burs (modeled as rigid bodies)
Depths of Cut (DOC)	1, 2	mm	Applied displacement loading condition
Enamel Young’s Modulus (E)	84,000	MPa	Cowper-Symonds Model
Dentin Young’s Modulus (E)	18,000	MPa	Cowper-Symonds Model
Pulp Young’s Modulus (E)	2	MPa	Cowper-Symonds Model
Enamel Density	2958	kg/m³	Material property input
Dentin Failure Strain	0.05	N/A	Cowper-Symonds parameter
Maximum Enamel Stress (3 mm bur, 1 mm DOC)	136.98	MPa	von Mises stress peak
Maximum Dentin Stress (3 mm bur, 2 mm DOC)	140.43	MPa	Highest recorded von Mises stress
Maximum Pulp Stress (3 mm bur, 2 mm DOC)	1.036	MPa	Stress transfer through dentin
Mesh Element Type	Four-nodded tetrahedral	N/A	Discretization method
Grid Independence Mesh Size	0.15	mm	Optimized element size for stability

Key Methodologies

Anatomical Reconstruction: A 3D model of a human maxillary first molar was generated from DICOM CT data using 3D Slicer, followed by geometric refinement (smoothing) in Fusion 360 and ANSYS Space Claim 2024 to ensure mesh compatibility.
Material Modeling: Dental structures (enamel, dentin, pulp) were defined as deformable bodies using the Cowper-Symonds constitutive model, selected for its ability to simulate high-strain-rate deformation behavior in hard biological tissues without requiring temperature inputs.
Tool Definition: Round diamond burs (1, 2, and 3 mm diameters) were modeled as rigid bodies to simplify the simulation and focus computational resources on tissue deformation.
Meshing and Validation: The models were discretized using four-nodded tetrahedral elements. A grid independence study confirmed that a 0.15 mm mesh size provided optimal balance between computational speed and result accuracy.
Boundary Conditions and Loading: The lower surfaces of the tooth roots were fixed (zero degrees of freedom). Cutting was simulated via a remote displacement load, applying 360 degrees of angular rotation and linear displacement corresponding to the 1 mm or 2 mm Depth of Cut (DOC).
Simulation Execution: Explicit dynamic analysis was performed, enabling erosion properties to simulate material removal during the short-term cutting scenarios.

Commercial Applications

The findings from this FEA study are highly relevant for optimizing tools and procedures in the dental and biomedical engineering sectors:

Dental Tool Design and Manufacturing: Provides quantitative data to guide the design of next-generation diamond burs, focusing on optimal diameter and grit size combinations to minimize stress concentrations and prevent iatrogenic damage.
Clinical Protocol Optimization: Establishes evidence-based guidelines for dentists regarding maximum safe Depth of Cut (DOC) and appropriate bur selection for specific cavity preparation stages (e.g., initial access vs. bulk removal).
Biomechanical Simulation Software: Validates the use of dynamic FEA and the Cowper-Symonds model for accurately predicting mechanical response in complex, anisotropic biological structures like teeth, enhancing the fidelity of future dental simulation platforms.
High-Speed Machining of Hard Tissues: The stress distribution data informs general engineering principles for high-speed abrasive machining of brittle, highly mineralized materials, applicable beyond dentistry (e.g., orthopedic surgery tools).
Fatigue and Longevity Studies: The quantified stress accumulation in dentin and pulp provides a foundation for future experimental validations concerning the long-term fatigue life and structural integrity of teeth subjected to repeated restorative procedures.

View Original Abstract

Background/Objectives: Dental cavity preparation is a critical procedure in restorative dentistry that involves the removal of decayed tissue while preserving a healthy tooth structure. Excessive stress during tooth preparation leads to enamel cracking, dentin damage, and long term compressive pulp health. This study employed finite element analysis (FEA) to investigate the stress distribution in dental structures during cavity preparation using round diamond burs of varying diameters and depths of cut (DOC). Methods: A three-dimensional human maxillary first molar was generated from computed tomography (CT) scan data using 3D Slicer, Fusion 360, and ANSYS Space Claim 2024 R-2. Finite element analysis (FEA) was conducted using ANSYS Workbench 2024. Round diamond burs with diameters of 1, 2, and 3 mm were modeled. Cutting simulations were performed for DOC of 1 mm and 2 mm. The burs were treated as rigid bodies, whereas the dental structures were modeled as deformable bodies using the Cowper-Symonds model. Results: The simulations revealed that larger bur diameters and deeper cuts led to higher stress magnitudes, particularly in the enamel and dentin. The maximum von Mises stress was reached at 136.98 MPa, and dentin 140.33 MPa. Smaller burs (≤2 mm) and lower depths of cut (≤1 mm) produced lower stress values and were optimal for minimizing dental structural damage. Pulpal stress remained low but showed an increasing trend with increased DOC and bur size. Conclusions: This study provides clinically relevant guidance for reducing mechanical damage during cavity preparation by recommending the use of smaller burs and controlled cutting depths. The originality of this study lies in its integration of CT-based anatomy with dynamic FEA modeling, enabling a realistic simulation of tool-tissue interaction in dentistry. These insights can inform bur selection, cutting protocols, and future experimental validations.

Tech Support

Original Source

DOI: https://doi.org/10.3390/prosthesis7040084

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