Effect of Phosphoric Acid Etching Duration on Direct Resin-Based Composite Restorations in Permanent Anterior Teeth

Overview

The goal of this clinical trial is to learn if reducing the phosphoric acid etching (PAE) time affects the performance of direct resin-based composite (RBC) restorations in permanent anterior teeth. It will also learn about the safety of using a shortened PAE protocol. The main questions it aims to answer are: Does a shorter PAE time lead to more or less marginal staining in restored teeth? What sensitivity or other clinical issues do participants experience after restoration using different PAE times? Researchers will compare a reduced PAE protocol to a standard PAE protocol to see how each affects the outcome of Class III and IV anterior restorations. Participants will: Receive one or two direct RBC restorations using either a shortened or standard PAE protocol Visit the clinic for follow-ups at baseline, and at 1, 2, 3, and 5 years after restoration Have sensitivity and restoration quality evaluated using clinical exams, photographs, and questionnaires

This clinical trial, "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," or ETCH-PRO for short, aims to investigate whether reducing the duration of phosphoric acid etching (PAE) impacts the effectiveness and safety of direct resin-based composite (RBC) restorations in permanent anterior teeth. Specifically, it seeks to answer: DOES A SHORTER PAE TIME AFFECT MARGINAL STAINING IN RESTORED TEETH? WHAT POSTOPERATIVE SENSITIVITY OR OTHER CLINICAL ISSUES DO PARTICIPANTS EXPERIENCE WITH DIFFERENT PAE TIMES? Researchers at the University Center for Dental Medicine Basel UZB will compare a reduced PAE protocol to a standard PAE protocol. Participants will receive one or two direct RBC restorations using either protocol and attend follow-up visits at baseline (7-10 days post-op), and at 1, 2, 3, and 5 years after restoration. During these visits, sensitivity and restoration quality will be assessed through clinical exams, photographs, and questionnaires. DETAILED DESCRIPTION BACKGROUND AND RATIONALE Phosphoric acid etching (PAE) is crucial for enhancing enamel bond strength in restorative dentistry. When using etch-and-rinse adhesives, PAE is necessary for successful dentin bonding. However, with self-etch adhesives, PAE of dentin is not recommended due to potential negative effects on adhesion. The increasing use of universal adhesives offers clinicians flexibility in choosing between etch-and-rinse and selective enamel etching techniques. A key challenge with selective enamel etching is the risk of inadvertently etching the dentin, which can compromise adhesion and the longevity of the restoration. Recent laboratory studies suggest that shortening PAE duration does not negatively affect bond strength, potentially mitigating the risks associated with accidental dentin etching. However, clinical data on the long-term outcomes of direct RBC restorations in anterior teeth using reduced PAE times is limited. This study aims to address this gap by evaluating the clinical performance of RBC restorations in anterior permanent teeth using a reduced PAE protocol compared to a standard protocol. The study specifically includes teeth requiring Class III or Class IV restorations due to: Proximal carious lesions with cavitation Replacement of defective restorations Necessary proximal reshaping (e.g., for developmental anomalies, proximal gaps, or esthetic concerns like black triangles) Class IV cases are strictly limited to non-fracture-related reshaping. The study operates under the null hypothesis, stating there is no significant difference in clinical outcomes between the two PAE protocols. Confirmation of this could support adopting reduced PAE durations in routine practice, potentially improving procedural efficiency and minimizing iatrogenic effects. RISK/BENEFIT ASSESSMENT STUDY OVERVIEW All procedures adhere to established, evidence-based restorative practices, using CE-marked materials and standardized protocols to ensure patient safety and consistency. This study is classified as Risk Category A according to ClinO, Art. 61, indicating minimal risks and burdens. ANTICIPATED CLINICAL BENEFITS While participants may not experience immediate personal benefits, their involvement will contribute valuable data to improve clinical protocols and outcomes for future patients. RESIDUAL RISKS AND ADVERSE DEVICE EFFECTS (ADES) The materials used comply with CE marking requirements, presenting minimal residual risks. Minor postoperative discomfort or sensitivity may occur but are considered rare and manageable. RISKS DUE TO CONCOMITANT TREATMENTS No specific risks from concomitant treatments are anticipated. Each participant's medical history will be reviewed during screening to monitor potential interactions. PARTICIPATION RISKS AND SAFETY MEASURES Participants are fully informed about the study's procedures, potential risks, and the lack of direct benefits. Written informed consent is obtained before participation. Close monitoring will ensure adverse events are promptly addressed. RISK-MITIGATION STRATEGIES Comprehensive risk analysis and procedural safeguards Proper training and calibration of all clinical personnel Clear patient communication and continuous monitoring Standardized procedures to minimize discomfort and risks RISK-BENEFIT ASSESSMENT The minimal and manageable risks are outweighed by the potential benefits of improving long-term restorative outcomes and informing future best practices. OBJECTIVES PRIMARY OBJECTIVE To compare the frequency of marginal staining in anterior direct RBC restorations between the standard and reduced PAE protocol groups. SECONDARY OBJECTIVES To assess the frequency of postoperative hypersensitivity levels following restoration To comprehensively evaluate the overall quality of the restorations based on clinical, esthetic, and functional parameters ENDPOINTS PRIMARY ENDPOINT Frequency of marginal staining in direct RBC restorations, assessed using the Category A2 guideline from the FDI criteria, incorporating the SQUACE method. SECONDARY ENDPOINTS Frequency and severity of pulpal hypersensitivity and pulpal status at 7-10 days post-treatment (FDI criteria B3) Comprehensive evaluation of restoration quality based on FDI criteria: Surface luster and surface texture (FDI A1) Color match (FDI A3) Caries at the restoration margin (FDI B1) Dental hard tissue defects (FDI B2) Fracture of material and retention (FDI F1) Marginal adaptation (FDI F2) Proximal contact quality (FDI F3), supplemented by testing with metal matrices (25-100 µm) Form and contour (FDI F4) Occlusion and wear (FDI F5) Patient satisfaction (FDI M1) using a VAS scale (0-10) Evaluations will be conducted at baseline, 1, 2, 3, and 5 years post-placement. Magnifying loupes and predefined-tip probes (250 µm) will be used. For FDI criteria F2, B1, and B2, margins will be analyzed via the SQUACE method. STUDY DESIGN This is a single-center, randomized, controlled trial with two parallel study arms, conducted at the University Center for Dental Medicine Basel UZB. BLINDING: Assessors and participants are blinded; operators are not, due to procedural differences COMPARATOR: Conventional etch-and-rinse vs. reduced PAE protocol ALLOCATION RATIO: 1:1 FRAMEWORK: Non-inferiority design ELIGIBILITY CRITERIA INCLUSION CRITERIA Adults (≥18 years) with signed informed consent Indication for Class III or IV RBC restoration due to: Proximal carious lesion with cavitation Defective restoration requiring replacement Necessary proximal reshaping Vital teeth with normal sensitivity VAS \<3 for preoperative sensitivity/biting discomfort Good oral hygiene and clinical periodontal health EXCLUSION CRITERIA Inability to achieve proper isolation Class IV restorations due to trauma or extensive wear Missing antagonist tooth without replacement Intent to bleach within 5 years post-restoration Allergies to materials used Pregnancy or lactation Health conditions impairing participation SEX AND GENDER CONSIDERATIONS Sex and gender are not considered significant variables, as restorative needs and outcomes do not vary by these factors. Key influencers include caries risk and technique. SAMPLE SIZE AND RATIONALE Total: 66 participants (33 per arm). The size accounts for a 10% dropout rate, with power calculations based on published marginal discoloration data. STUDY INTERVENTION All participants receive direct RBC restorations: TEST GROUP: 10-second total-etch with simultaneous enamel and dentin application CONTROL GROUP: Standard etch-and-rinse: 15-30 seconds on enamel, 10-15 on dentin Same materials for both: Adhesive: Adhese Universal RBC: Tetric plus Flow and Fill All procedures follow standardized restorative protocols. STUDY PROCEDURES One or two restorations per participant Recruitment from UZB patient base Randomization: Computer-generated (Castor), stratified by age, gender, and restoration class Assessments: FDI criteria (blinded evaluator) VAS for sensitivity Intraoral photos at all timepoints FOLLOW-UP SCHEDULE: Baseline (7-10 days post-op) 1, 2, 3, and 5 years STUDY DURATION AND SCHEDULE Total duration: \~6 years First subject in: May 2025 Last subject out: May 2031 STUDY CENTER University Center for Dental Medicine Basel UZB Department of Periodontology, Endodontology, and Cariology Mattenstrasse 40 CH-4058 Basel, Switzerland STATISTICAL CONSIDERATIONS Significance level (α): 0.05 Power (1-β): 0.80 Kaplan-Meier survival analysis and log-rank test for group comparison DATA PRIVACY Compliance with ISO 14155, GDPR, HIPAA Data pseudonymized and securely stored (Castor) Access restricted to authorized personnel Lay summary results shared with participants Data archived for 20 years ETHICAL CONSIDERATIONS Routine, low-risk intervention Excludes vulnerable populations Equal gender representation ensured Minimal risks, mitigated through staff training and close monitoring Aim: Advance restorative dentistry and improve long-term patient outcomes