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

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)