Does phosphoric acid etching time affect front-tooth composite fillings?
Official title: Effect of Phosphoric Acid Etching Duration on the Performance of Direct Resin-Based Composite Restorations in Permanent Anterior Teeth: A Randomized Controlled Single-Center Trial
Run by University Hospital, Basel, Switzerland · NCT06991842 · Data updated 2026-11-12
We will test whether shortening phosphoric acid etching time changes how well direct composite fillings work for adults needing Class III or IV front-tooth restorations.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 66 (estimated) |
| Sponsor | University Hospital, Basel, Switzerland Academic / other |
| Locations | 1 site (Basel, Canton of Basel-City) |
| Status | Recruiting |
| Started | June 1, 2025 |
| Main results expected | May 31, 2031 |
| Study ends | December 31, 2031 |
| Registry record updated | August 5, 2025 |
| Trial ID | NCT06991842 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Adults (18+) with vital anterior teeth who need one or two Class III or IV resin-based composite restorations, have good oral hygiene, and low preoperative sensitivity are ideal candidates.
✕Probably not a fit
Patients with non-vital or extensively damaged teeth, high preoperative sensitivity, poor oral hygiene, active periodontal disease, or inability to attend long-term follow-up are less likely to benefit.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This randomized, single-center trial at the University Center for Dental Medicine Basel compares a reduced phosphoric acid etching (PAE) protocol with a standard PAE protocol for Class III and IV anterior resin-based composite restorations. Participants receive one or two direct composite restorations and are followed at baseline (7–10 days) and at 1, 2, 3, and 5 years. Outcome measures include marginal staining, postoperative sensitivity, and overall restoration quality assessed by clinical exams, standardized photographs, and patient questionnaires. Safety of the shortened PAE protocol is monitored throughout follow-up.
Why it matters
Potential benefit: If successful, a shorter etching protocol could preserve restoration quality while reducing sensitivity and chair time for patients.
How similar studies have gone: Laboratory and some clinical work on selective or shortened enamel etching with universal adhesives have shown promising results, but long-term randomized data specifically for anterior Class III/IV restorations are limited.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: Signed informed consent by the participant Age 18 years or older Indication for a Class III or Class IV resin-based composite (RBC) restoration on an anterior permanent tooth due to one or more of the following conditions: Proximal carious lesion with cavitation Defective restoration requiring replacement Necessary proximal reshaping due to developmental anomalies (e.g., peg teeth, proximal gaps from Bolton discrepancies, orthodontic tooth position, or esthetic concerns like black triangles caused by periodontal tissue recession) Vital teeth with regular sensitivity Sufficient language skills to understand and comply with study procedures Preoperative Visual Analog Scale (VAS) scores \< 3 for tooth sensitivity and biting discomfort Good oral hygiene, including the ability to maintain effective oral hygiene Clinical periodontal health (intact periodontium or a reduced periodontium due to non-periodontal causes or after periodontal treatment) Exclusion Criteria: Inability to achieve sufficient isolation and contamination control during restorative procedures Class IV restoration required due to crown fracture, crown-root fracture, extensive tooth wear, or carious lesion affecting the incisal edge Missing antagonist tooth without prosthodontic replacement Intent to undergo professional tooth bleaching within five years following the Class III or IV restoration (Note: Professional tooth bleaching must be completed at least two weeks prior to study enrollment) Known or suspected allergy to any constituents of the materials used (e.g., methacrylates or local anesthetics) Pregnancy or lactation Acute or chronic health conditions that may impair study participation (e.g., systemic diseases, oral conditions, or treatments that interfere with study procedures)
Where it's running
-
University Center for Dental Medicine Basel UZB
Basel, Canton of Basel-City, Switzerland Recruiting
Study contacts
- Principal investigator: Florin Eggmann, PD Dr. med. dent. — University of Basel
- Study coordinator: Florin Eggmann, PD Dr. med. dent.
- Email: florin.eggmann@unibas.ch
- Phone: +41 61 267 26 80
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.