A total of 63 patients(age: 7-13, 30 boys and 33 girls), who received orthodontic treatment at the Affiliated Third Hospital of Soochow University, Department of Stomatology of Changzhou First People Hospital, were recruited from February 2015 to June 2017. The patients were divided into three groups according to the random number table: experimental group (group A): Nd:YAG laser (Equipment: LightWalker, Brand: Fotona, Model: M021-5AF/1) removal of gingiva; experimental group (group B): electrosurgical removal of the gingiva; control group (group C): traditional surgical removal of the gingiva.
The following selection criteria were applied: (1) no systemic blood diseases; (2) blood clotting time and other blood profiles were normal before treatment; (3) the delayed growth of permanent teeth was caused by hypertrophy of the gums;(4) the gap left by the missing teeth was sufficient for the eruption of a permanent tooth. The position and growth direction of the permanent tooth were confirmed by X-ray. If necessary, the oral cone beam CBCT was used to diagnose the direction of the tooth axis. Cases showing other causes that impeded the eruption of the teeth, such as multiple teeth, root development, or cysts, were excluded. This study involving human participants were reviewed and approved by The First People’s Hospital of Changzhou, the third Affiliated Hospital of Soochow University (202059), written informed consent to participants in this study was provided by the participants’ legal guardian next of kin.
The basic data of each child were collected, concerning name, gender, age, ethnicity, physical condition, history of systemic diseases, oral health, and health habits.
The children were randomly divided into three groups. All operations were performed by the same maxillofacial surgeon. The operation was performed after local infiltration anesthesia through lidocaine injection. Group A received a laser ablation of hypertrophic gingiva (Nd: pulse width: SP; pulse frequency: 50Hz; average output power: 4.5W) to expose the crown for the normal eruption of permanent teeth. Laser hemostasis (Nd: pulse width: VLP; pulse frequency: 20Hz; average output power: 4.00W) was used to control bleeding. Group B received electric knife-assisted removal of gingiva. Group C received the traditional surgical removal of gingiva with 11 blade. No suture was needed. Good oral hygiene was maintained. The total operative time, the duration of pain after gingival excision, and VAS pain intensity scores, gingival healing time, and intraoperative coordination were all recorded by one trained physician. Pain intensity was assessed using a Visual Analogue Scale (VAS) score (0 to 100mm), with a VAS marker of 1-25mm for mild pain; 26-50mm for moderate pain; 51-75mm for severe pain; 76-100mm for unbearable pain.[3, 7, 8] Two days after the operation, the patient was followed up by telephone to determine the pain persistence. One week after the operation, the patient was revisited to observe the healing of the gingiva. At six months during the follow-up, this physician checked and recorded the periodontal indicators of permanent teeth, including gum index (GI), plaque index (PLI), and probing depth (PD).
1.2.1 Detection sites
The mesial, distal, and middle of the labial surface of the permanent tooth after the orthodontic forced eruption.
1.2.2 Periodontal indexes
The GI was scored as follows: 0=normal gingiva, 1=mild edema, no bleeding on probing (BOP), 2=hyperemia and edema, bleeding on probing (BOP), 3=obvious redness and swelling, automatic bleeding tendency. PLI was scored as follows: 0=no plaque on gingival margin, 1=invisible plaque at the gingival margin but the probe could scrape, 2=a moderate amount of plaque at the gingival margin or adjacent surface, 3=a large amount of food debris at gingival crevice or gingival margin and adjacent surface. Probing depth referred to the distance from the gingival margin to the bottom of the periodontal pocket or the bottom of the gingival crevice.
1.2.3 Detection methods and data processing
In the case of unknown patients grouping, according to the numerical random table order, the periodontal indexes were elicited by the same periodontologist. Each site was measured three times and the results of each index were averaged as the final periodontal index of this patient.
1.3 Statistical methods
Statistical analysis was performed using SPSS 20.0 statistical software. One-way ANOVA was used for data comparison between groups. P<0.05 was considered statistically significant.