Introduction

In endodontic practice, (POP) management is crucial, this unpleasant state might be anticipated, particularly in teeth that exhibit symptomatic apical periodontitis, pulp necrosis, and preoperative discomfort [1]. Consequently, it is believed that controlling it is essential to maximize the effectiveness of the treatment [2]. Peri-radicular tissues are vulnerable to injury from a variety of mechanical, chemical, and microbial sources [3]. Additionally, the instruments and approaches employed in treatment highly effects the status of peri-radicular area [4]. Numerous techniques have been attempted to treat (POP), such as the use of corticosteroids and analgesics [2].

One technique to treat POP is form of cold therapy called cryotherapy, which has grown in popularity because of its ability to reduce muscular spasms, manage edema, and relieve pain [5]. It provides pain alleviation and lessens tissue damage via a series of biophysical actions [6]. This is achieved by minimizing oxygen consumption and cellular metabolic activity [6]. The production of free radicals, which fuel inflammation, is reduced by this method. Interestingly, a “hunting phenomenon” takes place when tissue temperature drops below a specific threshold, which is approximately 15 °C [7]. One proposed mechanism underlying cryotherapy’s analgesic effect involves an initial phase of vasoconstriction followed by subsequent vasodilation, which may contribute to reduced nociceptor activity and inflammation [7]. It also slows down nerve signal transmission. The myelinated A-delta fibers, which speed up the transmission of pain impulses, entirely stop working around 7 °C [7]. At 3 °C, however, the nonmyelinated C-fibers that provide delayed pain and temperature sensations cease to operate [7]. Additionally, cryotherapy causes vasoconstriction, which reduces swelling by narrowing blood vessels and preventing fluid from seeping into the tissues [7]. The temperature differential between the tissue and the administered therapy, the length of exposure, the properties of the cooling agent, and the features of the targeted tissue are some of the variables that affect how efficient cryotherapy is [7].

Substance P (SP) is one of these proinflammatory mediators that has been found to be a crucial neuropeptide in neurogenic inflammation and nociceptive transmission [8]. It is released from sensory nerve endings in response to tissue injury and inflammatory stimuli, where it promotes vasodilation, plasma extravasation, and recruitment of inflammatory cells [8]. Particularly in the tooth pulp, it causes edema and plasma extravasation, which alters permeability and causes vascular abnormalities [9]. An increase in tissue volume is the result of capillary dilatation and fluid transudation [10]. Pressure may increase as a result of swelling inside the tooth pulp, which is enclosed by hard calcified walls [8]. Since it activates the dental nerves, this increase in pressure is interpreted as pain [11]. Because of its high association with symptomatic pulpitis and its proven use as a trustworthy biochemical marker for neurogenic pain in earlier endodontic research, SP was chosen as the study’s focal point [9].

This study evaluates both postoperative pain (POP) and Substance P (SP) levels to provide a comprehensive assessment of cryotherapy’s effectiveness in endodontic treatment. By examining the relationship between biochemical markers and clinical symptoms, the study further explores the correlation between pain scores and SP levels in patients with symptomatic apical periodontitis undergoing cryotherapy. The techniques investigated include intraoral cryotherapy using gel packs, intracanal cryotherapy in the form of a final flush with cold saline, or irrigation with cold sodium hypochlorite (NaOCl) throughout the chemo-mechanical preparation process.

The null hypothesis was that the experimental groups receiving cryotherapy and the control group would not differ significantly in POP or SP levels.