Researchers investigated the incidence and severity of impacted teeth with fenestration or fenestration at several dental facilities across Japan. The online survey found that the anterior maxillary region had the highest number of impacted teeth, mostly in the canine region [15]. The eruption of permanent teeth is often delayed when gingival tissue thickens due to premature loss of deciduous tooth and trauma. With effective correction, the teeth can erupt at the normal position, thus reducing the occurrence of malocclusion [11, 12, 16, 17]. Forced eruption can preserve the natural root system and related periodontal architecture, resulting in years of additional service for the patient [18]. The success of surgical exposure combined with orthodontic traction had been reported to exceed 90% [1].

The purpose of this study was to evaluate the efficacy of three surgical methods for gingivectomy of permanent anterior teeth with delayed tooth eruption in children with regard to (1) surgical records and intraoperative pain: the total operative time (min), the duration of pain after gingival excision (d), VAS pain intensity scores (0 to 10 cm), gingival healing time (d) and (2) Postoperative periodontal indicators: gingival indexes (GI), plaque indexes (PLI), probing depth (PD).

The clotting mode of the electric knife can be used to close the blood vessels at the end of the wound, which can not only eliminate intraoperative bleeding, but also provide a good view of the surgical area without suturing [19]. An experimental study by Wang et al. showed that 45 children who underwent routine surgery or electrosurgical resection of gingival slices all burst out normally, and the gingiva adhesion and periodontal conditions were good after the eruption of teeth. However, there were statistically significant differences (P < 0.01) in bleeding time, operation time, bleeding amount and cooperation of children after gingival resection by electric knife, indicating that high frequency electrosurgical incision is superior to traditional surgical incision [4]. Electrosurgery provides homeostasis by coagulation, seals the capillary and lymphatic vessels, and permits an adequate contouring of the soft tissues. However, high frequency electrosurgical equipment cuts tissue and clots blood by heating and cauterizing, in the use of the electric knife, the paste flavor produced by cauterizing may discomfort the children, make them less cooperative, and prolong the procedures. As an inherent problem in electrosurgery, the use of high-speed evacuators near the operating area can reduce the odor produced [20].

Lasers are being widely used in oral surgery. And laser soft tissue surgery has become gradually accepted in children [21, 22]. Goldman et al. reported the first laser-assisted oral surgery in 1964 [14]. Sarver and Yanosky had summarized that the soft-tissue laser result in a shorter operative time and faster postoperative recuperation [23]. Treated with low-level laser therapy (LLLT) [24], children feel less pain, bleeding, and fear, and are more cooperative. The Nd: YAG laser used in this study emits a laser of 1064 nm to penetrate into the gingiva by a moderate depth, bring much less thermal damage and anxiety to the children [17, 25,26,27,28]. Mingwei Li [29] also found that low-level laser can effectively reduce the pain associated with surgical treatment. The result of Li’s experiment is also consistent with this study. This study found a significant difference in total operative time, pain duration, pain intensity, and healing time between laser surgery group (group A) and routine surgery group (group C) (P < 0.05). Laser surgery can shorten operative duration, simplify surgical procedures, and reduce postoperative pain and operation-induced fear, all making it highly applicable to children patients [30]. Of course, laser surgery also has obvious disadvantages, such as expense of operatory and upkeep. The major concerns in laser surgery are exposure to laser radiation. Therefore, protective measures must be established, along with proper training of operators and consideration of fire hazards [31].

Final periodontal health is a fundamental key to evaluate the success of therapy for impacted teeth. It is of great advantage to remove periodontal bacteria during the treatment of children with oral hygiene, to prevent gingivitis during orthodontic surgery, and to maintain the periodontal health of patients [32]. Surgical exposure of these impacted teeth is accomplished using various approaches. The appropriate surgical procedure and orthodontic treatment plan will result in a stable, predictable, and aesthetic result [33]. In this study, we did not find significant differences in periodontal indexes among three groups when the permanent teeth emerged at 6 months after the operation. PD values were all within the normal range (PD < 3 mm), meanwhile, no clinical manifestation differences were observed. Some researchers had reported no significant difference in gingival healing between electrosurgery and conventional surgery [34], which was confirmed in this study. This may suggest that although different surgical methods were selected for gingival resection on the crown side of impacted teeth, this factor did not significantly affect the periodontal status after tooth eruption. During normal tooth eruption process, gingival tissue has its own physiological development process [35].

At present, all three methods are clinically applied in gingivectomy of children's permanent anterior teeth to aid eruption, but there are few studies on the evaluation of the three methods. In the study of gingivectomy management of drug-induced gingival overgrowth, some scholars found that scalpel gingival resection and laser surgery had own advantages in plaque scores, bleeding scores, probing pocket depths, pain experience and other aspects respectively [36]. In addition, other studies suggest that electrocautery and laser treatment did not differ significantly in performing gingivectomy procedure and can be used to remove overgrowth of the gingiva with the same efficiency and wound healing power [37]. Even some clinicians have reported greater tactile sense with a scalpel [38]. Given that, it reminds us that the selection of surgical methods for children gingivectomy to aid permanent anterior teeth needs to be considered in many ways.

Pain is defined as “An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage” [39]. The first limitation of this study is that the diversity of individuals' pain perception, as well as the external background information they received prior to their participation in the study, can influence patients' pain responses. The complexity and subjectivity of pain that may alter an individual's pain experience, such as fear, may be particularly important considerations [40]. As a special treatment group, children's subjective treatment experience is a factor that doctors should pay attention to when making decisions. Thus, the Kolcaba comfort-behavior scale could be incorporated into the study design in the future.

In addition, there was no significant difference in total operation time, pain duration, pain intensity, healing time, and GI, PLI, PD of eruptive permanent teeth after six months of treatment between the Nd: YAG laser surgery and the high-frequency electrosurgery. Based on the current findings, it is suggested that future studies should focus on evaluating the effectiveness of these two surgical procedures.