Low Crystalline Hydroxyapatite Coating on Titanium Implants

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Solution Overview

Problem

Conventional methods for coating titanium implants with hydroxyapatite face issues such as high crystallinity leading to poor biocompatibility, non-uniformity, and peeling of the coating layer due to high temperature processes and complex procedures, which hinder integration with bone remodeling processes.

Innovation Solution

A method involving a low-concentration calcium phosphate solution at room temperature (15°C to 30°C) for 1 to 3 hours to form a low crystalline hydroxyapatite coating with network- or island-like morphology, eliminating the need for strict temperature and pH control, enhancing bioabsorbability and bioactivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If plasma spraying is used to coat titanium with hydroxyapatite, then the coating layer forms rapidly, but the high temperature causes non-uniform coating and high crystallinity leading to poor biocompatibility

Engineering Contradiction:
Improvecoating formation speedVSAvoidcoating uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the temperature parameter from high temperature (plasma spraying) to room temperature (15-30°C), which fundamentally alters the coating formation mechanism. This temperature change enables uniform coating formation without the thermal damage and non-uniformity associated with high-temperature plasma spraying, while still achieving rapid coating formation through chemical precipitation.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If plasma spraying is used to coat titanium with hydroxyapatite, then the coating layer forms rapidly, but the high crystallinity causes the coating to be refractory to removal by osteoclasts

Engineering Contradiction:
Improvecoating formation speedVSAvoidbiocompatibility
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the crystallinity parameter by conducting the coating process at room temperature instead of high temperature. This results in low-crystalline hydroxyapatite formation, which maintains biocompatibility and allows the coating to be removed by osteoclasts, enabling participation in bone remodeling processes.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional wet coating methods are used, then the coating process is simple, but the procedure requires long coating time and strict temperature and pH control

Engineering Contradiction:
Improveprocess simplicityVSAvoidcoating time
Core Design Contradiction:
Ease of manufactureVSLoss of time

Solution Approach 1:

The patent optimizes the concentration parameter of calcium phosphate solution (1.0-10.0 mM) and temperature parameter (15-30°C) to achieve rapid coating formation. This allows the coating process to complete within 1-3 hours without requiring strict pH control or extended treatment times, significantly improving efficiency while maintaining simplicity.

Inventive Principle:
Principle #35Parameter changes

4Strength

If high crystallinity hydroxyapatite is used for coating, then the coating provides mechanical strength, but it does not take part in the remodeling process of bones

Engineering Contradiction:
Improvecoating mechanical strengthVSAvoidintegration with bone remodeling
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent changes the crystallinity parameter by using room temperature coating processes, resulting in low-crystalline hydroxyapatite that maintains mechanical strength while enabling integration with bone remodeling processes. The low crystallinity structure allows the coating to be degraded and absorbed by osteoclasts, facilitating active participation in bone remodeling.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method results in a bioabsorptive coating that integrates with bone remodeling, prevents peeling, and enhances interfacial bonding, promoting osteoconductivity and osteogenesis, while simplifying the process and reducing costs.

Implementation Method 1

mixing a phosphate ion solution with a calcium ion solution to prepare a calcium phosphate solution, wherein the calcium phosphate solution has a concentration of 1.0 mM to 10 mM, dipping and storing the titanium or titanium alloy implant in the calcium phosphate solution for 1 hour to 3 hours at the temperature of 15°C to 30°C, wherein the resulting thin film of low crystalline hydroxyapatite

Methodology Applied
Scientific EffectPrecipitation: Precipitation

Data Source

PatentEP2444027B2Method for coating an implant with net-shaped or island-shaped low-crystallized hydroxyapatite
Publication Date: 2022.01.19 OSSTEMIMPLANT CO LTD
  • EP2444027B2 patent drawingFigure 1~2
  • EP2444027B2 patent drawingFigure 3~4
  • EP2444027B2 patent drawingFigure 5~6

AI summary

The present invention relates to a method for coating a surface of a titanium implant, which is widely used as a grafting material, with low crystalline hydroxyapatite, and an implant coated with low crystalline hydroxyapatite having network- or island-like morphology, by the same method. The method includes 1) pretreating a surface of a titanium or titanium alloy implant, 2) adding each of a phosphate ion solution and a calcium ion solution to the pretreated titanium or titanium alloy implant, and 3) dipping and storing the titanium or titanium alloy implant in the calcium phosphate solution for 1 hour or more.