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NCT Number: NCT07560761

Contribution of a* to Dental Bleaching After Combined Dental Bleaching

A prospective, non-randomized, single-arm interventional clinical study with a before-after design will be conducted to assess changes in CIELab color parameters and the Whiteness Index for Dentistry (WID) following a standardized combined dental bleaching protocol. The study aims to evaluate the contribution of the a* parameter (green-red axis) to overall dental whiteness.

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Key information

Conditions

Healthy

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

About this study

Tooth whitening is one of the most commonly requested aesthetic dental treatments, requiring objective and reproducible methods to quantify color changes. The CIELab color system (L*, a*, b*) and the Whiteness Index for Dentistry (WID) are widely used for this purpose.

While increases in L* and decreases in b* are recognized as the main contributors to dental whitening, the role of the a* parameter remains unclear. Variations in a*, including the presence of negative values or changes in sign during treatment, have been insufficiently studied.

A prospective, non-randomized, single-arm interventional clinical study with a before-after design will be conducted to evaluate changes in L*, a*, b*, and WID following a combined dental bleaching protocol consisting of an in-office phase with hydrogen peroxide and an at-home phase with carbamide peroxide.

Spectrophotometric measurements will be performed at baseline, after the in-office phase, and after completion of the at-home phase. The study will also analyze the relationship between changes in CIELab parameters and WID.

The study will be conducted in accordance with ethical standards and will be approved by the corresponding institutional review board. All participants will provide written informed consent prior to inclusion.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age 18 to 65 years
  • Good oral health
  • Presence of natural anterior teeth (incisors, canines, premolars)
  • Anterior teeth without restorations
  • Indication for tooth bleaching treatment
  • Ability to comply with study procedures and visits

Exclusion criteria

  • Smoking
  • Previous tooth bleaching treatment
  • Pregnancy
  • Breastfeeding
  • Restorations in anterior teeth
  • Presence of diseases affecting tooth color
  • Conditions that may interfere with study outcomes

Treatment and study plan

Combined Dental Bleaching

Procedure

The intervention consists of an in-office bleaching phase with two 20-minute applications of 40% hydrogen peroxide, followed by an at-home bleaching phase using 16% carbamide peroxide applied with custom trays for 90 minutes daily. Treatment will continue until color stabilization is achieved, defined as a change in WID of less than 2.6 units between two consecutive weekly measurements.

Primary outcomes

  1. Change in Whiteness Index for Dentistry (WID)

    Time frame: From baseline to end of treatment (up to 12 weeks).

    Change in WID values calculated from CIELab parameters (L*, a*, b*) between baseline and the end of treatment (up to 12 weeks).

Secondary outcomes

  1. Change in L* parameter

    Time frame: Baseline to end of treatment (up to 12 weeks).

    Difference in L* values between baseline and the end of treatment (up to 12 weeks) measured using spectrophotometry.

  2. Change in a* parameter

    Time frame: Baseline to end of treatment (up to 12 weeks).

    Difference in a* values between baseline and the end of treatment (up to 12 weeks), including assessment of sign changes.

  3. Change in b* parameter

    Time frame: Baseline to end of treatment (up to 12 weeks)

    Difference in b* values between baseline and the end of treatment (up to 12 weeks), measured using spectrophotometry.

  4. Correlation between WID and CIELab parameters

    Time frame: At end of treatment (up to 12 weeks).

    Assessment of the relationship between changes in WID and changes in L*, a*, and b*.

Study contacts

Contact information is provided by the study sponsor or research team.

José Amengual-Lorenzo, PhD

CONTACT

[email protected]

+34616941167

Rubén Agustín Panadero, MSc; Phd

CONTACT

[email protected]

+34653098901

Sponsors and collaborators

Lead sponsor

University of Valencia

Other

Registry information

Official study title

Contribution of the a* Parameter to Dental Bleaching After Combined Bleaching: A Prospective Non-randomized Single-arm Interventional Clinical Study

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
May 1, 2026
Registry last updated
May 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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