In Vitro Method for Assessing Laser Titanium Interactions Using Er,Cr:YSGG and Diode Lasers

Summary

This protocol describes a standardized in vitro method for evaluating thermal and surface effects on titanium during Er,Cr:YSGG, and diode laser irradiation using manufacturer-recommended soft-tissue cutting settings. Direct contact thermometry and multimodal surface analysis provide a reproducible workflow for characterizing wavelength-dependent laser titanium interactions.

Abstract

This study presents a standardized in vitro protocol to evaluate the thermal response and surface alterations of titanium during Er,Cr:YSGG and diode laser irradiation under manufacturer-recommended soft-tissue settings. Custom Grade 4 titanium cylinders with an internal channel enabled direct-temperature measurement via an embedded thermocouple, allowing controlled assessment of laser-induced thermal changes. To ensure geometric consistency and minimize operator-dependent variability, a 3D-printed stabilization system was used to standardize the irradiation angle, sweep trajectory, and tip movement. Surface modifications following laser exposure were quantitatively and qualitatively characterized using complementary techniques, including profilometry for roughness analysis, scanning electron microscopy for micromorphologic evaluation, and atomic force microscopy for nanoscale topographic assessment. Diode-laser irradiation produced power- and time-dependent temperature elevations, with the highest parameter combinations exceeding the clinically accepted 10 °C safety threshold. In contrast, all tested Er,Cr:YSGG conditions remained below this limit, indicating distinct wavelength-dependent thermal behavior. Both laser systems induced significant increases in surface roughness relative to the untreated control surface, while imaging analyses revealed wavelength-dependent differences in micro and nanoscale morphology. Collectively, this protocol provides an experimental framework for systematic investigation of laser-titanium interactions and may support safer, evidence-based parameter selection for laser-assisted soft tissue procedures performed near implant components.   

Introduction

Laser-assisted soft tissue procedures are widely employed during second-stage implant surgery and peri-implant mucosal management, where irradiation often occurs in close proximity to titanium components^1,2. In such clinical situations, understanding the thermal behavior of titanium and the potential for surface alterations is essential, as excessive temperature elevation or surface disruption may jeopardize peri-implant bone integrity and long-term implant stability^3,4. Existing literature provides valuable insights into wavelength-dependent laser tit....

Protocol

Preparation of titanium specimens
Grade 4 titanium cylinders (5 mm × 10 mm, sandblasted large grit acid etched (SLA) surface) were cleaned with 70% ethanol for 30 s. The specimens were placed on a clean surface and air-dried for 10 min. The flat irradiation surface of each cylinder was inspected to confirm the absence of visible debris. Each cylinder was positioned in the 3D-printed stabilization holder, with the flat surface oriented upward and the lateral thermocouple slot accessible. All ethanol waste and any contaminated consumables generated during specimen preparation and cleaning were collected and disposed of in accordance....

Results

Temperature analysis
Across all Er,Cr:YSGG groups, temperature change remained below the 10 °C safety threshold, with values ranging between –2.65 °C and +2.20 °C. Power had a significant effect on temperature change (p < 0.001), whereas irradiation duration showed no significant influence (p = 0.898). The lowest temperature was observed in E2 (2.75 W–40 s: –2.65 °C). In contrast, diode laser irradiation produced markedly higher temperature elevations (3.25–15.55 °C), with both power and duration .......

Discussion

This study demonstrated that laser titanium interactions are strongly influenced by wavelength, output power, and the combined effects of power and exposure duration. Er,Cr:YSGG irradiation consistently produced temperature elevations below the clinically accepted 10 °C threshold associated with thermal bone injury^3,4, whereas diode laser irradiation showed a progressive thermal load, exceeding this limit at 2.2 W for both 20 s and 40 s. These findings align.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
3D-printed stabilization holder	Custom-made	Custom-made / Not applicable	3D printed stabilization unit designed to fix irradiation angle and handpiece path.
Atomic Force Microscope (EzAFM-Compact)	Nanomagnetics Instruments, Oxford, UK	URL: https://www.nanomagnetics-inst.com/product/scanning-probe-microscopy/ezafm	Used for nanoscale surface topography and roughness characterization.
Digital Multimeter (Keithley 2000, 6½ Digit)	Keithley Instruments	URL: https://www.tek.com/en/products/keithley/digital-multimeter/keithley-2000-series-6-digit-multimeter-scanning	Used with K-type thermocouple for temperature measurement.
Epic Diode Laser (940 nm)	Biolase, Irvine, CA, USA	URL: https://www.biolase.com/products/dental-lasers-soft-tissue/epic-x/	Continuous-wave diode laser system (940 nm); adjustable 0.5–10 W output; used for soft-tissue mode irradiation.
Er,Cr:YSGG Laser System (Waterlase iPlus, 2780 nm)	Biolase, Irvine, CA, USA	URL: https://www.biolase.com/products/dental-lasers-all-tissue/waterlase-iplus-intl/	Er,Cr:YSGG laser (2780 nm) used with MZ-5 Ziptip, 9 mm; operated in gingivectomy mode with continuous air–water spray.
Ethanol, 70% (v/v)	Ulusoy Kozmetik	URL: https://www.ulusoykozmetik.com/urun/tr/105_ulusoy-etil-alkol-70%25C2%25B0	Specimen surface cleaning
EzAFM Control and Analysis Software	Nanomagnetics Instruments, Oxford, UK	URL: https://www.nanomagnetics-inst.com/product/scanning-probe-microscopy/ezafm	Used for AFM control, data acquisition, and image processing.
IBM SPSS Statistics 25	IBM Corp., Armonk, NY, USA	Version 25	Used for statistical analyses including normality testing, non-parametric comparisons, and two-way ANOVA.
K-type Thermocouple	Not specified	Not applicable	K-type thermocouple probe used for temperature acquisition.
Microscope Control Software (Quanta FEG 250)	Thermo Fisher Scientific (formerly FEI), Hillsboro, OR, USA	URL: https://www.thermofisher.com	Used for SEM image acquisition and instrument control.
MZ-5 Ziptip (9 mm)	Biolase	URL: https://store.biolase.com/products/7200712-pkg-mz5-9mm-ziptips-20-pack-wl-md	Tip used with Er,Cr:YSGG handpiece.
Oil-free compressed air	Not specified	Not applicable	Used to remove debris from titanium surfaces.
Paraffin Wax	MumveMum (sold via Trendyol)	URL: https://www.trendyol.com/mumvemum/hazir-parafin-1-kg-p-31671380	Used to coat thermocouple wire to reduce thermal interference.
Profilometer (Surftest SJ-201)	Mitutoyo, Tokyo, Japan	URL: https://www.bergeng.com/m m5/downloads/mti/sj201.pdf?srsltid =AfmBOoq2vJN7b4UPc2Yg-aO1 zhsL64p6vFDHSWJ54M_x5gdI8 KkIJgaV	Used for Ra measurements across 2 × 2 mm scanning area.
Scanning Electron Microscope (Quanta FEG 250)	Thermo Fisher Scientific (formerly FEI), Hillsboro, OR, USA	URL: https://www.thermofisher.com	SEM imaging at 250×–5000× magnifications.
Tips E4, 400 µm, 4 mm	Biolase	URL: https://store.biolase.com/products/7400016-tips-e4-400-µm-4mm-surgical-30-qty	Fiber used for diode laser irradiation.
Titanium cylinders (Grade 4, SLA surface, 5×10 mm)	Naxis, Germany	Custom made	Custom-made cylinders with 5 mm internal channel for thermocouple.