This study aims to evaluate how different phases of the menstrual cycle affect pain after dental treatments. Specifically, it investigates two types of pain:

Postoperative sensitivity (pain felt after the filling procedure), and Rebound pain (pain that begins after the numbness from anesthesia wears off). The study was conducted with 35 women who received two dental fillings at different times in their cycle: once during the menstrual phase and once during the ovulatory phase.

A local anesthetic (inferior alveolar nerve block) was used before treatment, and pain was measured using a 0-10 visual scale at several time points after the procedure.

The goal of the study is to understand whether hormonal changes during the menstrual cycle can affect pain levels after dental work. This information could help dentists improve pain management strategies for women and personalize treatment timing.

This clinical trial investigates the effect of menstrual cycle phases on postoperative pain perception following direct posterior composite restorations. It addresses the hypothesis that hormonal fluctuations during the menstrual cycle may alter pain thresholds and nociceptive processing, potentially influencing the intensity and timing of postoperative dental pain.

Estrogen and progesterone, the primary hormones involved in the menstrual cycle, have been shown to modulate pain through their effects on the central and peripheral nervous systems, inflammatory mediators, and endogenous opioid pathways. Despite extensive research on hormonal influences in systemic pain, their specific effects on dental pain-particularly postoperative sensitivity and rebound pain-remain understudied.

The study employed a double-blind, split-mouth, randomized clinical design to minimize inter-subject variability and strengthen internal validity. A total of 35 female participants with regular menstrual cycles underwent two posterior Class II composite restorations, one during the menstrual phase (MPG) and one during the ovulatory phase (OPG). Menstrual phases were confirmed using self-reported cycle calendars and mobile tracking applications.

All restorative procedures were standardized and performed under local anesthesia. Composite restorations were completed using Clearfil Majesty Posterior and Clearfil Universal Bond Quick (self-etch mode). An inferior alveolar nerve block (IANB) was administered using articaine hydrochloride with epinephrine (1:100,000).

Pain was assessed using the Visual Analog Scale (VAS, 0-10) at predefined time points to evaluate two types of postoperative discomfort:

Postoperative Sensitivity (POS): assessed on Day 1, Day 2, and Day 3 following the procedure.

Rebound Pain (RP): assessed at Hour 4, Hour 8, and Hour 12 after the resolution of anesthesia.

Statistical analyses were performed using Cochran's Q test and McNemar's test for within-subject comparisons, and Chi-Square or Fisher's Exact Test for between-group differences. Bonferroni correction was applied for multiple comparisons to control type I error, with p < 0.05 considered statistically significant.

This study provides new insights into the chronobiological factors affecting dental pain and contributes to the evidence base for individualized pain management in female dental patients. The findings may support more personalized scheduling of restorative procedures and better prediction of analgesic needs based on menstrual cycle phases.

Inclusion Criteria:

• Female participants aged 18-45 years
• Regular naturally occurring menstrual cycles (26-32 days)
• No use of hormonal contraceptives
• Good general health
• Vital posterior molar teeth requiring direct composite restorations
• Good oral hygiene and periodontal health

Exclusion Criteria:

• Irregular menstrual cycles or known hormonal disorders
• Presence of dentin hypersensitivity in the affected tooth
• Regular use of psychiatric or other medications
• History of bruxism, temporomandibular disorders (TMD), or chronic pain syndromes Pregnancy or lactation
• Use of analgesics, oral contraceptives, or anti-inflammatory drugs within 48 hours before treatment
• Severe periodontal disease, dental pain, or need for endodontic treatment

Eligibility is limited based on biological sex due to menstrual cycle-related variables

This study does not plan to share individual participant data.

Both the operator performing the restorations and the researcher assessing postoperative sensitivity and rebound pain were blinded to the menstrual cycle phases of the participants.