Symptomatic irreversible pulpitis, often referred to as “toothache”, is a frequent dental emergency characterized by severe spontaneous pain, sensitivity to percussion, and difficulty in pain control with conventional analgesics. When associated with symptomatic apical periodontitis, the inflammatory process extends beyond the pulp to periapical tissues, further intensifying the pain experience [1].

Endodontic therapy remains the treatment of choice in such situations, with reported success rates between 74% and 97% depending on the presence of preoperative periapical lesions [2]. In addition to root canal treatment, occlusal reduction has historically been proposed as an adjunctive measure to decrease mechanical stimulation of sensitized nociceptors, thereby potentially reducing postoperative pain [3].

However, the irreversible nature of occlusal reduction and the increasing emphasis on minimally invasive dentistry necessitate a critical evaluation of its real clinical benefit. This systematic review aimed to investigate whether occlusal reduction provides a significant reduction in postoperative pain in patients with symptomatic irreversible pulpitis and apical periodontitis undergoing endodontic treatment.

This systematic review evaluated the effect of occlusal reduction on postoperative pain in patients with symptomatic irreversible pulpitis associated with apical periodontitis. Overall, the findings indicate that occlusal reduction may provide limited short-term pain relief within the first 12 - 24 hours following root canal treatment; however, its overall effectiveness remains inconsistent across studies [6][8].

Two randomized controlled trials [6][8] demonstrated a statistically significant reduction in early postoperative pain, supporting the hypothesis that eliminating occlusal contacts may reduce mechanical loading and stimulation of inflamed periapical tissues [3]. In contrast, three other studies [4][5][7] failed to show a significant benefit, suggesting that postoperative endodontic pain is more strongly influenced by inflammatory mediators and neurogenic mechanisms than by occlusal forces alone [9]. These conflicting results indicate that occlusal reduction is not a universally effective strategy for pain control.

A notable and counterintuitive finding was reported by Ghimire etal. [7], who observed higher pain levels at days 5 - 6 postoperatively in patients over 45 years of age who underwent occlusal reduction. This challenges the traditional rationale of occlusal adjustment as a pain-relieving adjunct. Possible explanations include age-related changes in periodontal ligament mechanoreception, delayed inflammatory resolution, or altered pain perception in older patients. In addition, occlusal reduction may disrupt established occlusal balance, potentially leading to transient instability or compensatory functional adaptations that could exacerbate discomfort rather than relieve it. This finding highlights the importance of patient-related factors, particularly age and occlusal dynamics, in modulating the clinical response to occlusal modification.

Interpretation of the results is further limited by significant heterogeneity among the included studies [4]-[8]. Differences in study design, occlusal reduction protocols, sample sizes, and pain evaluation intervals complicate direct comparison. Moreover, variations in endodontic treatment strategies, such as single-visit versus multiple-visit procedures, may have influenced postoperative pain outcomes, as interappointment flare-ups are more frequently associated with multi-visit treatments. Differences in instrumentation techniques (manual, rotary, or reciprocating systems) may also affect apical debris extrusion and periapical tissue irritation, thereby confounding the isolated effect of occlusal reduction.

Importantly, the irreversible removal of tooth structure inherent to occlusal reduction must be considered in light of the principles of minimally invasive dentistry, as emphasized in the Introduction. In the absence of consistent and sustained clinical benefit, unnecessary removal of sound tooth structure cannot be justified and may contradict current conservative treatment philosophies.

Analgesic consumption, assessed in all included studies [4]-[8], did not differ significantly between occlusal reduction and control groups. This suggests that occlusal reduction does not reduce the need for pharmacological pain management and should not be viewed as an alternative to established analgesic protocols.

ClinicalImplications: Based on the available evidence, routine occlusal reduction cannot be recommended for all cases of symptomatic irreversible pulpitis or apical periodontitis. Its use should be limited to carefully selected situations in which clear clinical indicators of occlusal overload are present, such as visible wear facets, fremitus, marked tenderness related to hyperocclusion, or a patient’s clear sensation of a “high bite” on the affected tooth. Even in such cases, occlusal reduction should be performed conservatively and within a well-defined diagnostic framework.

Limitations: This review included only five clinical trials with heterogeneous methodologies, limiting the strength and generalizability of the conclusions. In addition, the literature search was restricted to studies published up to December 2022; therefore, results from major trials published thereafter may further clarify the clinical value of occlusal reduction. Future well-designed randomized controlled trials with standardized endodontic protocols, consistent pain assessment methods, and predefined subgroup analyses are required.

Occlusal reduction may reduce short-term postoperative pain in patients with symptomatic irreversible pulpitis and apical periodontitis, particularly within the first 24 hours [6][8], but evidence remains inconsistent [4][5][7]. It should be reserved for selected cases rather than applied as a routine adjunctive procedure.