---
title: Enhanced Enamel Whitening, Surface Hardness and Stain Resistance
description: "In vitro studies were performed to investigate the effects of irradiating enamel with a 9.3 µm CO2
 laser in enhancement of whiting and stain resistance."
---

[Clinical Studies | Convergent Dental ](https://www.convergentdental.com/clinical-studies)

# [Enhanced Enamel Whitening, Surface Hardness and Stain Resistance](https://www.convergentdental.com/clinical-studies/enhanced-enamel-whitening-surface-hardness-and-stain-resistance-by-9.3-µm-co2-laser-irradiation-an-in-vitro-pilot-study)

 Written by [Badreddine AH and Kerbage C](https://www.convergentdental.com/clinical-studies/author/badreddine-ah-and-kerbage-c) | Nov 18, 2022 3:12:29 PM

*Badreddine AH and Kerbage C*

### ABSTRACT ([Click here for full study](https://medwinpublishers.com/OAJDS/enhanced-enamel-whitening-surface-hardness-and-stain-resistance-by-93-um-co2-laser-irradiation-an-in-vitro-pilot-study.pdf))

### Objectives:

In vitro studies were performed to investigate the effects of irradiating incisor enamel with a 9.3 µm CO2 laser in enhancement of whiting, stain resistance and surface hardness. 

### Methods:

A 9.3 µm CO2 laser beam was used to irradiate the labial surface of incisors with 0.8 J/cm2 pulse fluence at 333 Hz automatically scanning a 5.8 mm2 area for 0.381 seconds repeated to cover the whole teeth surface. The teeth were divided into three groups of n=10 each: a control group that received 40% H2O2 gel for 20-minutes application time, an irradiated group followed with two 10-minute gel applications, and another irradiated group followed with two 20-minute gel applications. A spectroscopy device was used to analyze the overall color change (delta E) and degree of whitening. A 24-hour tea stain protocol was used to investigate the uptake of stain after the treatment procedure. Additionally, a small flat polished area on each sample was used to investigate microhardness before and after an acid challenge with pH 3.6 citric acid buffer. 

### Results:

Both irradiated groups showed an enhanced whitening effect, with a delta E that was 1-2 higher than the H2 O2 gel control group. The 10-minute application time was sufficient to reach the full benefit from irradiation. The irradiated groups showed increased resistance to acid solubility and reduced the absorption of tea stain. 

### Conclusion:

Irradiation with a 9.3 µm CO2 laser before application of whitening gel on incisor enamel increased the effect of whitening in half the time. It also provided an increased resistance to acid attack and staining.

[View full post](https://www.convergentdental.com/clinical-studies/enhanced-enamel-whitening-surface-hardness-and-stain-resistance-by-9.3-µm-co2-laser-irradiation-an-in-vitro-pilot-study)

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