This study is designed to compare two modern techniques used to restore decayed back teeth with tooth-colored filling materials. Some patients experience temporary discomfort or sensitivity after these types of dental treatments. The purpose of this study is to learn whether one technique may help reduce this short-term sensitivity compared to the other.

Adults who need fillings on both sides of their mouth are invited to participate. Each patient will receive one filling using each technique, placed in different teeth during the same appointment. The procedures will be performed using standard clinical methods and materials.

After treatment, participants will be contacted by telephone to report any discomfort at several time points during the first week. The interviewer will not know which technique was used for each tooth to ensure unbiased reporting. This information will help dentists better understand how these techniques affect patients' comfort in the days following treatment.

Postoperative tooth sensitivity is a common but often transient symptom following the placement of direct posterior resin composite restorations. Patients frequently report mild to moderate discomfort, particularly during the first few days after treatment, which can influence their perception of treatment success and overall satisfaction. While advances in adhesive dentistry and restorative materials have greatly improved clinical outcomes, postoperative sensitivity remains a relevant clinical concern.

This clinical trial is designed to compare two contemporary restorative techniques-the snow-plow technique and the resin coating technique following immediate dentin sealing-in terms of postoperative patient-reported pain during the first postoperative week. Both techniques aim to enhance marginal adaptation and reduce polymerization shrinkage stresses at the adhesive interface, thereby potentially minimizing pulpal irritation and postoperative discomfort.

Participants in this study are adult patients requiring Class II resin composite restorations on two comparable posterior teeth, typically located on opposite sides of the dental arch. Each participant will receive two restorations, one using the snow-plow technique and the other using the resin coating technique, in a split-mouth design. This approach allows each participant to serve as their own control, minimizing inter-patient variability and enabling a more reliable comparison between the two restorative strategies.

All procedures are performed under rubber dam isolation using standardized adhesive and restorative protocols to ensure clinical consistency. The snow-plow technique involves placing an uncured flowable bulk-fill resin on the cavity floor, immediately followed by the placement of a packable composite increment. Both materials are then light-cured simultaneously. This technique is intended to improve adaptation of the restorative material to cavity walls, displace voids, and reduce microleakage.

In the resin coating technique, immediate dentin sealing is performed following cavity preparation. A thin layer of flowable bulk-fill resin is then applied over the sealed dentin and light-cured before the placement of the final packable composite increment. This layer acts as a stress-absorbing liner, providing a flexible interface that may protect the pulp and reduce the transmission of shrinkage stresses during polymerization.

Operator calibration and adherence to standardized protocols are emphasized to ensure uniformity. All restorations are carried out by a single experienced clinician using the same materials, instruments, and curing devices to reduce variability related to operator technique.

Postoperative discomfort is assessed using a standardized visual analog scale (VAS) during structured telephone interviews conducted at baseline (before treatment), 24 hours, 72 hours, and one week postoperatively. Interviews are performed by an assessor who is blinded to the restorative technique used for each tooth to minimize reporting bias. Participants are specifically instructed to evaluate each treated tooth independently without making side-by-side comparisons.

This study does not involve any experimental drugs or non-standard clinical procedures. Both restorative techniques are widely accepted in routine clinical practice and use materials that are commercially available and approved for dental use. The primary objective is to evaluate the early postoperative pain experience associated with each technique, rather than to introduce a novel material or intervention.

The findings of this study will contribute to a better understanding of how restorative technique selection influences postoperative sensitivity, potentially informing evidence-based clinical decision-making in restorative dentistry. By comparing two established but mechanistically distinct approaches, this trial aims to provide clinically relevant information that may help dentists optimize patient comfort following posterior resin composite placement.

Inclusion Criteria:

• Adult patients aged 18-50 years.
• Systemically healthy individuals.
• Presence of two posterior teeth in different quadrants or contralateral sides of the same arch requiring Class II composite restorations.
• Teeth diagnosed with reversible pulpitis and vital pulps, confirmed clinically and radiographically.
• Teeth without previous restorations or carious lesions limited to dentin.
• Ability to provide informed consent and comply with study procedures and follow-up assessments.

Exclusion Criteria:

• Non-vital teeth, teeth with signs of irreversible pulpitis, periapical pathology, or extensive loss of tooth structure.
• Patients with systemic conditions or medications that may influence pain perception, healing, or sensitivity (e.g., chronic pain syndromes, analgesic use, immunosuppressive therapy), or very poor oral hygiene.
• Pregnant or breastfeeding women.
• Known allergy to dental materials used in the study.
• Inability to respond to follow-up calls or provide reliable pain assessments.
• Teeth with previous restorations, endodontic treatment, or cracks.

De-identified individual participant data (IPD) underlying the results will be shared, including demographic data, intervention assignment, and all primary and secondary outcome measures. Data will be available to qualified researchers upon reasonable request following publication of the study results, in accordance with institutional and ethical guidelines. Supporting materials, such as the study protocol and statistical analysis plan, will also be provided.

The outcomes assessor was blinded to the restorative technique used on each tooth. Telephone interviews were conducted using standardized scripts, and the interviewer was unaware of the allocation, referring to teeth by quadrant/side to minimize bias. The operator is not blinded due to the nature of the restorative procedures.