Root Canal Obturation by Electrochemical Precipitation of Calcium Phosphates

At a Glance

Metadata	Details
Publication Date	2022-03-14
Journal	Applied Sciences
Authors	Maximilian Koch, Victor Palarie, Maximilian Göltz, Marvin Kurzer, Manuel Zulla
Institutions	Friedrich-Alexander-Universität Erlangen-Nürnberg, Nicolae Testemițanu State University of Medicine and Pharmacy
Citations	2
Analysis	Full AI Review Included

Technical Documentation & Analysis: BDD Electrodes for Electrochemical Bioprecipitation

This document analyzes the research paper “Root Canal Obturation by Electrochemical Precipitation of Calcium Phosphates,” focusing on the application of Boron-Doped Diamond (BDD) electrodes. This analysis highlights 6CCVD’s capabilities in supplying the specialized MPCVD diamond materials required to replicate, scale, and advance this novel biomedical application.

Executive Summary

This research validates the use of Boron-Doped Diamond (BDD) electrodes as a platform for in situ electrochemical precipitation of biocompatible materials for endodontic applications.

Novel Application: BDD electrodes are successfully used to initiate the rapid precipitation of calcium phosphate (CaP) salts directly within restricted volumes (simulated and extracted root canals).
Material Synthesis: The precipitated material was unequivocally identified as brushite (CaHPO₄ * 2 H₂O), a highly biocompatible calcium phosphate salt, confirmed via XRD and RAMAN spectroscopy.
Mechanism of Action: Precipitation is triggered by the BDD-mediated electrochemical oxidation and degradation of maleic acid (a Ca²⁺ chelator/retardant), releasing free calcium ions.
Process Control: The amount of precipitate formed is directly correlated with the applied charge quantity (As), demonstrating electrochemical control over the material formation process.
Material Quality: SEM analysis confirmed the brushite crystals sealed dentin tubules and showed close attachment to the root canal walls.
Technical Requirements: The study utilized custom BDD-coated niobium wires (200 µm diameter) requiring specialized fabrication and precise material properties, a core competency of 6CCVD.

Technical Specifications

The following hard data points were extracted from the experimental results, focusing on the BDD material and electrochemical parameters.

Parameter	Value	Unit	Context
Electrode Material	BDD-coated Niobium Wire	N/A	Used for electrochemical oxidation and precipitation.
Electrode Dimensions	200 µm Diameter, 2.5 cm Length	µm, cm	Dimensions of the BDD-coated wire.
Custom Electrode Cross Section	Approximately 500	µm	Cross-section of the glued-wire BDD prototype used for canal insertion.
Applied Potential Range	6 - 16	V	Constant potential applied to initiate precipitation.
Precipitation Time (Reaction Tube)	2	min	Time required to achieve significant precipitate mass.
Precipitate Identification	Brushite (CaHPO₄ * 2 H₂O)	N/A	Confirmed via XRD and RAMAN analysis.
Observed Ca/P Ratio (EDX)	1.11 (Average 1.0 ± 0.02)	N/A	Consistent with brushite composition.
Optimal Precipitation Efficiency	~15	As	Efficiency decreased at higher charge quantities, suggesting surface blocking or heat issues.
Precipitate Porosity (µCT Analysis)	11.27 ± 7.47	%	Overall porosity of the final obturation material.
Minimal Sealing Distance (µCT)	< 100	µm	Maximal gap distance between precipitate and canal wall.

Key Methodologies

The experimental success hinges on the precise preparation of the precursor solution and the controlled application of the BDD electrode.

Precursor Solution Formulation: A highly saturated, chemically stable calcium phosphate (CaP) solution was created using maleic acid (C₄H₄O₄) as a chelating agent to retard precipitation.
- Molar Ratios: CaCO₃ (0.445 M) mixed 1:2 with Maleic Acid (0.89 M).
- Final Ca/P Ratio: 1:1, achieved by adding ammonium phosphates.
BDD Electrode Fabrication: BDD-coated niobium wires (200 µm diameter) were fabricated and glued together to form a prototype electrode with a narrow cross-section (approx. 500 µm) suitable for root canal insertion.
Electrochemical Precipitation: A constant potential (6-16 V) was applied to the BDD electrode, initiating the oxidation of maleic acid, which in turn released Ca²⁺ ions to form solid brushite precipitate.
In-Situ Obturation: Experiments were conducted in endodontic training blocks and extracted human teeth, requiring repeated cycles of precursor solution application, BDD treatment, drying, and plugging to fill the canal space.
Material Characterization:
- Phase Identification: X-ray diffraction (XRD) and Raman spectroscopy (RAMAN) confirmed the precipitate phase as brushite.
- Morphology/Composition: Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) analyzed crystal structure and Ca/P ratio.
- Sealing Quality: Micro-computed tomography (µCT) and X-ray imaging assessed material distribution, porosity, and wall attachment.

6CCVD Solutions & Capabilities

This research demonstrates a high-value, specialized application for BDD materials in the biomedical sector. 6CCVD is uniquely positioned to supply the custom BDD components necessary to transition this protocol from laboratory research to clinical development.

Applicable Materials

To replicate and scale this electrochemical obturation technique, researchers require high-quality, heavily boron-doped diamond material with controlled conductivity and geometry.

Research Requirement	6CCVD Material Recommendation	Rationale
High-Efficiency Anode	Heavy Boron-Doped Polycrystalline Diamond (PCD)	Provides the necessary high conductivity and chemical stability for efficient electrochemical oxidation of maleic acid and Reactive Oxygen Species (ROS) generation.
BDD Substrate	Custom BDD Wafers/Plates (up to 125mm)	Ideal for developing next-generation, integrated electrode arrays or micro-patterned BDD chips for multi-channel endodontic devices.
BDD Thickness Control	SCD/PCD Thickness (0.1 µm to 500 µm)	Precise control over BDD layer thickness allows optimization of electrode lifespan and current density, crucial for controlling the precipitation rate and minimizing heat generation (a noted limitation in the paper).

Customization Potential

The paper utilized custom BDD-coated wires and a glued prototype with a 500 µm cross-section, emphasizing the need for micro-scale, application-specific geometries.

Custom Dimensions: 6CCVD specializes in providing BDD plates and wafers up to 125mm, which can be precisely cut or shaped to match specific clinical tool dimensions, far exceeding the limitations of standard wire electrodes.
Micro-Fabrication: We offer advanced laser cutting and shaping services to create complex, narrow-profile BDD electrodes or micro-patterned arrays necessary for insertion into fine root canal structures.
Integrated Contacts: The need for robust electrical connection is critical. 6CCVD provides internal metalization services (Au, Pt, Ti, W) to ensure reliable, biocompatible electrical contacts for integrated BDD devices.
Surface Finish: For optimal performance and integration, 6CCVD offers ultra-low roughness polishing: Ra < 5nm for inch-size PCD/BDD, ensuring consistent electrochemical surface activity.

Engineering Support

The optimization of BDD-mediated precipitation requires expertise in electrochemistry and material science.

Protocol Optimization: 6CCVD’s in-house PhD team can assist researchers in optimizing BDD material selection (doping level, surface termination) for similar BDD-Mediated Bioprecipitation projects.
Efficiency and Heat Management: We provide consultation on electrode design to improve precipitation efficiency and manage thermal output, addressing the observed decrease in efficiency at high charge quantities (>15 As).
Biomedical Compliance: Our expertise ensures that the supplied BDD materials meet the stringent quality and purity requirements for biomedical and dental research applications.

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

View Original Abstract

Achieving adequate disinfection and preventing reinfection is the major goal in endodontic treatment. Variation in canal morphology and open porosity of dentine prevents achieving complete disinfection. Questionable biocompatibility of materials as well as a lack of sealing ability questions the usefulness of current obturation methods. With a novel disinfection approach based on the use of boron-doped diamond (BDD) electrodes having shown promising results it was the goal of this series of experiments to investigate the possibility of BDD-mediated in situ forming of a biocompatible obturation material. A combination of calcium phosphate and maleic acid was used as precursor solution while Ion Chromatography Mass Spectrometry (IC-MS), Raman spectroscopy (RAMAN), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), dye penetration and micro-computed tomography (µCT) were applied for characterizing the precipitate. It was possible to achieve a BDD-mediated precipitation of brushite in a clinically applicable timeframe. However, tight sealing of the canal system based on brushite could not be achieved.

Tech Support

Original Source

DOI: https://doi.org/10.3390/app12062956

References

2004 - Controversies in endodontics [Crossref]
2009 - Review of contemporary irrigant agitation techniques and devices [Crossref]
2006 - Quality guidelines for endodontic treatment: Consensus report of the european society of endodontology [Crossref]
2019 - Hand and ultrasonic instrumentation for orthograde root canal treatment of permanent teeth
2004 - Current challenges and concepts in the preparation of root canal systems: A review [Crossref]
2019 - Lack of evidence for the necessity of root canal obturation
2016 - Essential elder endodontics [Crossref]
2021 - Radiographic outcome of root canal treatment in general dental practice: Tooth type and quality of root filling as prognostic factors [Crossref]
2019 - Outcome of endodontic retreatment using 2 root canal irrigants and influence of infection on healing as determined by a molecular method: A randomized clinical trial [Crossref]