**1. Introduction**

The treatment of choice for symptomatic, persistent or enlarging periapical lesion after conventional re-root canal treatment is surgical endodontic treatment, which is aimed at resecting the root end and then creating a barrier at the apical end of the root with an inert material [1–3]. The goal of this treatment protocol is to salvage the tooth and prevent it

**Citation:** Ahmed, M.A.; Mughal, N.; Abidi, S.H.; Bari, M.F.; Mustafa, M.; Vohra, F.; Alrahlah, A. Factors Affecting the Outcome of Periapical Surgery; a Prospective Longitudinal Clinical Study. *Appl. Sci.* **2021**, *11*, 11768. https://doi.org/10.3390/ app112411768

Academic Editor: Gianrico Spagnuolo

Received: 23 August 2021 Accepted: 22 November 2021 Published: 10 December 2021

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from further damage by limiting the entry of microbes and their byproducts into the canal system, thus promoting the health of the tooth.

The success of surgical endodontic treatment mainly relies on the absence of clinical signs and symptoms and radiographic resolution of periapical lesions. Studies have shown that multiple factors may influence the outcome of periapical surgery such as age, gender, smoking, type of root-end filling material, size of the preoperative periapical lesion, and the presence of pretreatment signs and symptoms [3,4].

Smoking is considered one of the risk factors that can impede periapical healing. Smoking disturbs healing by limiting the supply of oxygenated blood and nutrients to the periapical area [5]. This in turn makes periapical tissue more susceptible to bacterial infection [6]. Additionally, it alters the synthesis of collagen, expedites bone loss, and interferes in the tissue repair process around the periapical area [7,8]. Furthermore, smokers have restricted defense mechanisms due to the deficiency of several immunological factors such as Tumor necrosis factor alpha (TNF-α) and Human beta defensin-2 (hBD-2) [9].

There have been numerous studies investigating the size of preoperative periapical lesions with periapical wound healing. It was observed that fibroblasts proliferate into a large bony defect after periapical surgery and form scar tissues instead of allowing osteoblasts for osseous regeneration [10], which in turn disrupts healing. However, the involvement of several molecular and cellular factors makes it more intricate [11]. Few studies have reported a better healing outcome with smaller lesions [3,12,13] while others find no statistically significant difference in outcome in relation to the size of periapical lesions [14,15].

The presence of preoperative signs and symptoms indicates the acute stage of periapical lesion. Acute lesions usually present with pain and swelling while chronic lesions are usually asymptomatic with or without the presence of sinus tract. A consensus has been observed that the presence of preoperative clinical signs and symptoms do not significantly influence postoperative healing [16,17] however, vice versa has also been reported in some studies [3,18].

In light of conflicting evidence and lack of prospective studies regarding the factors that determine the successful outcome, the current study was designed to evaluate the various preoperative factors affecting the outcome of surgical endodontic treatment.
