Preclinical Testing of Boron-Doped Diamond Electrodes for Root Canal Disinfection—A Series of Preliminary Studies

At a Glance

Metadata	Details
Publication Date	2022-04-07
Journal	Microorganisms
Authors	Maximilian Koch, Victor Palarie, Lisa Koch, Andreas Burkovski, Manuel Zulla
Institutions	Friedrich-Alexander-Universität Erlangen-Nürnberg, Nicolae Testemițanu State University of Medicine and Pharmacy
Citations	6
Analysis	Full AI Review Included

Technical Documentation & Analysis: Boron-Doped Diamond Electrodes for Endodontic Disinfection

Executive Summary

This research validates the efficacy of Boron-Doped Diamond (BDD) electrodes, fabricated via Chemical Vapor Deposition (CVD), as a superior method for electrochemical root canal disinfection. The findings directly support the application of 6CCVD’s advanced BDD materials in next-generation biomedical devices.

Core Value Proposition: BDD electrodes enable the in situ generation of Reactive Oxygen Species (ROS) through saline electrolysis, achieving predictable disinfection in complex root canal geometries where conventional irrigants fail.
Performance Metrics: Optimal electrochemical parameters were established in preclinical models: 5.5 V to 7.0 V and 9 mA to 38 mA applied for 2.5 to 6.0 minutes.
Antimicrobial Efficacy: BDD treatment significantly reduced Enterococcus faecalis biofilm survival to below 5% after just 1 minute of application, demonstrating efficacy often superior to Chlorhexidine (CHX) in multispecies biofilm models.
Geometry Advantage: The use of thin BDD-coated Niobium wires (down to 50 µm diameter) allows the electrode to reach the critical apical region (requiring an ISO size #30, 300 µm canal diameter), overcoming anatomical limitations inherent to traditional irrigation.
Material Requirement: The success hinges on high-quality, heavily boron-doped diamond films deposited onto custom metallic substrates (Niobium), a core specialization of 6CCVD.
Market Opportunity: This technology represents a significant advancement in endodontics, requiring scalable, high-precision BDD components for clinical translation.

Technical Specifications

The following hard data points were extracted from the preclinical testing protocols and results:

Parameter	Value	Unit	Context
Electrode Material	Boron-Doped Diamond (BDD)	N/A	Deposited via HFCVD
Substrate Material	Niobium (Nb)	N/A	Wires (99.9% purity)
Nb Wire Diameter (Prototype 1)	200	µm	Parameter Determination
Nb Wire Diameter (Prototype 2)	50	µm	Canine Model
Required Apical Diameter	300 (ISO #30)	µm	Minimum canal size for electrode insertion
Applied Voltage Range	5.5 to 7.0	V	In vitro and Canine Model
Applied Current Range	9 to 38	mA	Canine Model
Applied Current (In Vitro)	20	mA	Parameter Determination
Application Time Range	2.5 to 6.0	min	Optimal treatment duration
Irrigant Volume	5 to 8	mL	Saline (0.9% NaCl)
E. faecalis Survival (1.0 min BDD)	< 5	%	Compared to 100% baseline CFU
Biofilm Incubation Temperature	37	°C	Human and Canine tooth models

Key Methodologies

The BDD electrodes were fabricated using specialized CVD techniques tailored for high aspect ratio substrates (wires) and controlled boron incorporation.

Substrate Preparation: Niobium (Nb) wires (50 µm or 200 µm diameter) were pre-treated via sandblasting using Silicon Carbide (SiC) particles (17-74 µm) to enhance surface roughness and promote diamond adhesion.
Cleaning and Seeding: Wires were ultrasonically cleaned and subsequently seeded using nanodiamond dispersions (1:1000 or 1:10,000 dilution in ethanol).
CVD Setup: Boron-doped diamond coating was performed using a Hot-Filament Chemical Vapor Deposition (HFCVD) machine.
Filament Carburization: Tungsten filaments (220 mm, Ø 100 µm) were pre-heated for 18 hours at 65 A/mount to achieve stable conditions prior to deposition.
Doping Atmosphere: The BDD film was grown using a gas atmosphere consisting of methane, hydrogen, and trimethyl borate (TMB) as the boron source.
Electrode Configuration: Prototype 2 utilized the BDD-coated Nb wire as the anode (+) and a wired cannula as the cathode (-), separated by spirally formed insulating material, allowing for simultaneous saline irrigation and electrochemical treatment.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-specification BDD materials required to replicate, optimize, and scale this electrochemical disinfection technology for clinical use. Our MPCVD platform offers superior control over doping uniformity and film quality compared to traditional HFCVD methods.

Applicable Materials

To achieve the high electrochemical activity necessary for efficient ROS generation, the following 6CCVD materials are recommended:

Heavy Boron-Doped PCD (Polycrystalline Diamond): For high-volume production of the active electrode material. Our PCD wafers/plates can be processed into custom geometries (e.g., micro-rods or thin films on conductive substrates) with highly controlled boron concentration (up to 10²¹ atoms/cm³) to maximize conductivity and electrochemical efficiency.
Custom BDD-on-Metal Substrates: 6CCVD specializes in depositing BDD films directly onto customer-supplied conductive substrates, including Niobium (Nb), Tungsten (W), and Titanium (Ti), ensuring robust adhesion and optimal device integration for micro-scale endodontic tools.

Customization Potential

The research highlights the critical need for micro-scale, high-precision components (50 µm diameter wires) and complex electrode assemblies. 6CCVD’s advanced fabrication capabilities directly address these requirements:

Research Requirement	6CCVD Capability	Technical Advantage
Micro-Scale Substrates	Custom deposition onto high aspect ratio substrates (wires, rods, tubes).	Enables fabrication of electrodes small enough to reach ISO #30 (300 µm) canal apices.
Custom Geometry	Precision laser cutting and shaping services.	Allows for rapid prototyping and production of complex electrode designs (e.g., the Prototype 2 cannula/wire assembly).
Metalization Interface	Internal metalization services (Au, Pt, Ti, Pd, W, Cu).	Critical for creating reliable electrical contacts and biocompatible interfaces for the anode/cathode connections, especially on Niobium substrates.
Scalability	MPCVD plates/wafers up to 125 mm diameter.	Ensures high-volume, cost-effective production necessary for clinical device commercialization.
Polishing	SCD polishing to Ra < 1 nm; PCD polishing to Ra < 5 nm.	Provides smooth, defect-free surfaces crucial for consistent electrochemical performance and biocompatibility.

Engineering Support

6CCVD’s in-house PhD team offers comprehensive engineering consultation to accelerate the transition of this research into a commercial product:

Doping Optimization: Assistance in tuning boron doping levels to maximize the yield of specific Reactive Oxygen Species (ROS) required for targeted antimicrobial action while minimizing potential host tissue side effects.
Electrode Design: Support in optimizing the BDD film thickness (0.1 µm to 500 µm) and geometry for improved current density distribution and mechanical robustness within the narrow root canal environment.
Biomedical Integration: Consultation on material selection and surface preparation for similar electrochemical disinfection projects in endodontics, periodontics, and implantology.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

While numerous approaches have meanwhile been described, sufficient disinfection of root canals is still challenging, mostly due to limited access and the porous structure of dentin. Instead of using different rinsing solutions and activated irrigation, the electrolysis of saline using boron-doped diamond (BDD) electrodes thereby producing reactive oxygen species may be an alternative approach. In a first step, experiments using extracted human teeth incubated with multispecies bacterial biofilm were conducted. The charge quantities required for electrochemical disinfection of root canals were determined, which were subsequently applied in an animal trial using an intraoral canine model. It could be shown that also under realistic clinical conditions, predictable disinfection of root canals could be achieved using BDD electrodes. The parameters required are in the range of 5.5 to 7.0 V and 9 to 38 mA, applied for 2.5 to 6.0 min with approximately 5 to 8 mL of saline. The direct generation of disinfective agents inside the root canal seems to be advantageous especially in situations with compromised access and limited canal sizes. The biologic effect with respect to the host reaction on BDD-mediated disinfection is yet to be examined.

Tech Support

Original Source

DOI: https://doi.org/10.3390/microorganisms10040782

References

2004 - Controversies in endodontics [Crossref]
2009 - Review of contemporary irrigant agitation techniques and devices [Crossref]
2014 - Ability of new obturation materials to improve the seal of the root canal system: A review [Crossref]
2015 - Root canal morphology and configuration of 179 maxillary first molars by means of micro-computed tomography: An ex vivo study [Crossref]
2016 - Evaluation of root canal configuration of maxillary and mandibular anterior teeth using cone beam computed tomography: An in-vivo study
2017 - Effectiveness of various irrigation protocols for the removal of calcium hydroxide from artificial standardized grooves [Crossref]
2013 - A comparative study of biofilm removal with hand, rotary nickel-titanium, and self-adjusting file instrumentation using a novel in vitro biofilm model [Crossref]
2019 - Lack of evidence for the necessity of root canal obturation
2017 - Comparison of simplistic biofilm models for evaluating irrigating solutions
2011 - Persistent extraradicular infection in root-filled asymptomatic human tooth: Scanning electron microscopic analysis and microbial investigation after apical microsurgery [Crossref]