This randomized, double-blind, split-mouth clinical trial evaluates the effectiveness of at-home dental bleaching using customized nightguards fabricated by digital (3D-printed CAD-CAM) and conventional methods, with and without reservoirs. Adult participants with good general and oral health and a baseline tooth shade of A2 or darker undergo bleaching with 10% carbamide peroxide. Outcomes include tooth color change (subjective and spectrophotometric measures), tooth sensitivity, gingival irritation, patient comfort, and patient satisfaction over time.

This study compares the effectiveness of at-home dental bleaching using customized conventional vacuum-formed trays and digitally fabricated (3D-printed CAD-CAM) trays. It also compares tray designs with and without reservoirs using a randomized split-mouth design.

Each participant receives both tray fabrication approaches and both reservoir conditions, distributed according to randomized allocation. Bleaching is performed with 10% carbamide peroxide. Participants are followed during and after treatment to assess tooth color change, tooth sensitivity, gingival irritation, comfort, and satisfaction.

Tooth color is assessed using both visual and spectrophotometric methods. A customized positioner is used to standardize the measurement location throughout the study.

Inclusion Criteria:

• Adults aged 18 years or older
• Good general and oral health
• No current medical treatment (self-reported)
• No need for surgical, endodontic, periodontal, or restorative dental treatment
• At least six upper and six lower anterior teeth free of caries and restorations
• Maxillary central incisors with baseline shade A2 or darker
• Willingness to follow the study protocol and use the study-provided oral hygiene products/instructions

Exclusion Criteria:

• Previous tooth bleaching treatment
• Orthodontic appliances or prostheses that interfere with treatment
• Severe intrinsic discoloration (e.g., tetracycline staining, fluorosis, or endodontically treated teeth with discoloration)
• Pregnancy or lactation
• Bruxism
• Gingival recession, dentin exposure, visible enamel cracks, or other conditions associated with increased sensitivity
• Use of anti-inflammatory or analgesic medication during the study period (according to protocol)

Individual participant data (IPD) will not be shared because the dataset contains potentially identifiable clinical information from a small sample treated at a single center, and no data-sharing plan was included in the original participant consent.

Participants and clinical outcome evaluators were unaware of group assignments. Data analysis was performed by a separate researcher who was not involved in treatment administration or outcome assessment. Due to the nature of tray fabrication and delivery, personnel involved in tray preparation may not have been blinded.