Quantitative In Vivo Monitoring of Early Erosion-Associated Enamel Optical Changes Using Swept-Source Optical Coherence Tomography.

This study aims to evaluate the ability of swept-source optical coherence tomography (SS-OCT) to detect early enamel optical changes associated with erosive tooth wear under clinically relevant in vivo conditions. The study also investigates whether salivary stimulation induced by sugar-free chewing gum influences enamel optical properties following repeated erosive challenges.

A prospective, longitudinal, within-subject study with a fixed-sequence design was conducted. Twenty-two healthy adults aged 23-33 years participated after meeting predefined inclusion and exclusion criteria. All participants completed two sequential experimental phases separated by a two-day washout period. A fixed-order design (Phase A followed by Phase B) was selected to standardize erosive exposure and minimize variability during repeated intraoral OCT measurements. As an exploratory study, randomization was not performed.

In both phases, participants underwent repeated erosive challenges using commercially available orange juice (pH 3.4). During each challenge, participants swished 25 mL of orange juice for 30 seconds followed by a 30-second rest interval, repeated continuously for 10 minutes (total exposure: 250 mL). Erosive challenges were performed three times daily at three-hour intervals over three consecutive days under investigator supervision.

Phase A consisted of repeated erosive challenges without intervention. In Phase B, participants followed the identical erosive protocol but chewed sugar-free chewing gum for 15 minutes immediately after each erosive challenge to stimulate salivary flow and enhance natural buffering and remineralization mechanisms.

All participants used standardized fluoridated toothpaste and soft-bristled toothbrushes beginning two days before the study and throughout the experimental period. Unstimulated salivary flow rate was measured before enrolment, and participants with salivary flow rates below 0.2 mL/min were excluded.

The primary outcome measure was enamel integrated reflectivity (IR), quantified from SS-OCT A-scan analysis as an indicator of enamel optical changes associated with early demineralization. A commercially available swept-source OCT system equipped with an intraoral probe was used for image acquisition. The middle third of the labial surface of the maxillary right central incisor (tooth 11) served as the standardized imaging site. Custom acrylic positioning devices and anatomical landmarks were used to improve reproducibility of repeated measurements.

SS-OCT imaging was performed at six standardized time points during each study day: baseline before the first erosive challenge (t1), after the first challenge (t2), after the second challenge (t3), after the third challenge (t4), following a three-hour rest period (t5), and the following morning after overnight salivary exposure (t6). Image acquisition parameters, drying procedures, and positioning were standardized for all participants.

Integrated reflectivity values were calculated from predefined regions of interest using established OCT image analysis methods. Five adjacent A-scans were averaged to reduce signal noise. Statistical analyses included paired sample t-tests for predefined comparisons and linear mixed-effects modelling to evaluate longitudinal changes while accounting for repeated measurements within participants. Statistical significance was set at α = 0.05.

The study was approved by the appropriate institutional ethics committee, and written informed consent was obtained from all participants before enrolment. The study complied with the principles of the Declaration of Helsinki. Findings are expected to provide evidence regarding the feasibility of SS-OCT as a non-invasive clinical tool for monitoring early erosive enamel changes and evaluating preventive interventions under clinically relevant oral conditions.

Study Overview

• Status: Completed
• Conditions: Dental Erosion; Erosive Tooth Wear
• Intervention / Treatment: Diagnostic test: Swept-Source Optical Coherence Tomography (SS-OCT); Other: Orange Juice Erosive Challenge; Behavioral: Sugar-Free Chewing Gum Stimulation

• Study Type: Interventional
• Enrollment (Actual): 22
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Healthy adults aged 23-33 years. Presence of intact maxillary right central incisor (tooth 11) suitable for repeated SS-OCT imaging.

Good general and oral health. Normal unstimulated salivary flow rate (≥0.2 mL/min). Willingness to comply with all study procedures, including repeated erosive challenges and SS-OCT examinations.

Provision of written informed consent prior to participation.-

Exclusion Criteria:

Presence of active dental caries, restorations, enamel defects, cracks, or erosive lesions on the study tooth.

Ongoing orthodontic treatment affecting the study tooth. History of systemic diseases or medications known to affect salivary flow or enamel mineralization.

Unstimulated salivary flow rate <0.2 mL/min. Pregnancy or breastfeeding. Known allergy or intolerance to orange juice or sugar-free chewing gum. Current smokers or tobacco users. Inability or unwillingness to comply with study procedures or attend all scheduled visits.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Repeated Erosive Challenge With and Without Chewing Gum Stimulation; Participants underwent two sequential experimental phases in a fixed-order design. During Phase A, participants received repeated orange juice erosive challenges without chewing gum stimulation for three consecutive days. Following a two-day washout period, all participants completed Phase B, during which the identical erosive challenge protocol was repeated with 15 minutes of sugar-free chewing gum immediately after each erosive challenge. Swept-source optical coherence tomography (SS-OCT) imaging was performed repeatedly throughout both phases to monitor enamel optical changes. Each participant served as his or her own control.

Diagnostic test: Swept-Source Optical Coherence Tomography (SS-OCT); A commercially available swept-source optical coherence tomography (SS-OCT) system (OCS1300SS, Thorlabs Inc., USA) equipped with an intraoral probe was used to obtain non-invasive cross-sectional images of enamel. The labial surface of the maxillary right central incisor was imaged under standardized conditions at six time points per day during each 3-day experimental phase to quantify enamel integrated reflectivity.; Other: Orange Juice Erosive Challenge; Participants swished 25 mL of commercially available orange juice (pH 3.4) for 30 seconds followed by a 30-second rest interval. This cycle was repeated continuously for 10 minutes (total exposure: 250 mL per session). The erosive challenge was performed three times daily at 3-hour intervals for three consecutive days during both experimental phases.; Behavioral: Sugar-Free Chewing Gum Stimulation; During Phase B, participants chewed one piece of sugar-free chewing gum (Wrigley's Extra® Peppermint) for 15 minutes immediately after each orange juice erosive challenge to stimulate salivary flow. This intervention was repeated after each of the three daily erosive challenge sessions over three consecutive days.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in enamel integrated reflectivity measured by swept-source optical coherence tomography (SS-OCT)	Description Integrated reflectivity (IR), derived from SS-OCT A-scan analysis, will be used to quantify changes in enamel backscattered light intensity associated with early erosion-related optical alterations. Higher IR values indicate increased optical scattering consistent with enamel demineralization.	Baseline through Day 3 of each study phase (6 measurements per day over two 3-day experimental phases).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Longitudinal changes in enamel integrated reflectivity during repeated erosive challenges	Longitudinal changes in integrated reflectivity will be evaluated using repeated SS-OCT measurements and linear mixed-effects modelling to assess cumulative enamel optical changes over time and between experimental phases.	Baseline through Day 3 of each experimental phase.

Collaborators and Investigators

• Sponsor: University of Malaya

Study record dates

Study Major Dates

• Study Start (Actual): June 21, 2016
• Primary Completion (Actual): June 24, 2016
• Study Completion (Actual): June 30, 2016

Study Registration Dates

• First Submitted: July 1, 2026
• First Submitted That Met QC Criteria: July 1, 2026
• First Posted (Actual): July 8, 2026

Study Record Updates

• Last Update Posted (Actual): July 8, 2026
• Last Update Submitted That Met QC Criteria: July 1, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Dental erosion; Non-invasive imaging; Salivary stimulation; Swept-source optical coherence tomography (SS-OCT); Enamel demineralization; Erosive tooth wear; Integrated reflectivity; In vivo longitudinal study
• Additional Relevant MeSH Terms: Stomatognathic Diseases; Tooth Diseases; Tooth Demineralization; Tooth Wear; Tooth Erosion
• Other Study ID Numbers: Ethics: DF RD1617/0054(P); UM-MOHE HIR Grant UM.C/HIR/MOH (Other Grant/Funding Number: Ministry of Higher Education, Malaysia)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

IPD Plan Description

Do not intend to make de-identified individual participant data publicly available.

The ethics approval and participant consent did not include provisions for sharing individual participant data.

Data will only be available upon reasonable request or not at all.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No