[Clinical study on liquid-phase concentrated growth factor combined with low-level laser therapy for improving...

Objective: To evaluate the clinical efficacy of liquid-phase concentrated growth factor (LPCGF) alone or in combination with low-level laser therapy (LLLT) under local micro-trauma activation for endogenous healing in the treatment of gingival papilla recession, and to explore the influencing factors. Methods: Patients with aesthetic complaints caused by gingival papilla recession who sought treatment at the Department of Periodontology, Stomatological Hospital of Xi'an Jiaotong University from July 2022 to August 2023 were enrolled in this study. A total of 155 gingival papilla recession sites from 40 patients were included. All sites were numbered after preoperative preparation and randomly divided into two primary groups using a random number table: micro-trauma group (20 patients, 81 sites) and injection-only group (20 patients, 74 sites). Subsequently, each primary group was further randomly subdivided into two subgroups respectively, forming four subgroups in total: Group T1 (micro-trauma combined with LPCGF injection, 10 patients, 37 sites); Group T2 (micro-trauma combined with LPCGF injection and LLLT, 10 patients, 44 sites); Group C1 (LPCGF injection alone, 10 patients, 33 sites); Group C2 (LPCGF injection combined with LLLT, 10 patients, 41 sites). Preoperative cone-beam CT (CBCT) examination and clinical measurements were performed to obtain anatomical parameters, including distance from bone crest to proximal contact point, crown width-length ratio, proximal contact length, interradicular distance and alveolar bone thickness. Meanwhile, gingival biotype, black triangle parameters and Norland & Tarnow classification of gingival papilla recession were recorded. The black triangle height (BTH) and black triangle area (BTA) were measured, and their changes (ΔBTH, ΔBTA) were assessed at 12 months postoperatively. Results: A total of 40 patients were enrolled, including 2 males and 38 females, with age of (30.67±5.20) years, involving 155 sites with gingival papilla recession. At 12 months postoperatively, the reductions in BTH and BTA were (1.21±0.47) mm and 0.75 (0.51, 1.10) mm² in Group T1, 1.03 (0.61, 1.27) mm and 0.85 (0.55, 1.11) mm² in Group T2, (0.42±0.65) mm and 0.21 (0.02, 0.94) mm² in Group C1, and (0.51±0.64) mm and 0.29 (0.02, 0.59) mm² in Group C2, respectively. Significant improvements in BTH and BTA were observed in all four groups compared with baseline (P<0.001, P<0.001, P<0.01, and P<0.01, respectively). No significant intergroup differences in ΔBTH and ΔBTA were found between Group T1 and Group T2, as well as between Group C1 and Group C2 (both P>0.05). However, visual analogue scale (VAS) assessments of swelling and pain within 7 days postoperatively demonstrated that, compared with the Group T1 and Group C1, the Group T2 and Group C2 presented significantly lower swelling VAS scores from the night of operation to postoperative day 3 (P<0.05), as well as significantly improved pain VAS scores from the night of operation to postoperative day 2 (P<0.05). For thin gingival biotype sites at 3, 6 and 12 months postoperatively, the improvements in ΔBTH and ΔBTA in the micro-trauma groups (Group T1+Group T2) were significantly superior to those in the injection-only groups (Group C1+Group C2) (ΔBTH: Z=3.64, -4.01, 3.46; ΔBTA: Z=-4.18, t=-6.02, t=-7.43; both P<0.001). Canonical correlation analysis revealed a significant correlation between the anatomical variable set and clinical efficacy indicators, with the first canonical correlation coefficient of R=0.486 (P<0.001). According to the standardized canonical weights of variables, alveolar bone thickness presented the strongest positive effect (weight=0.788), while interradicular distance showed a significant negative effect (weight=-0.516). Conclusions: Minimally invasive LPCGF therapy, alone or in combination with LLLT, effectively improves gingival papilla recession. Bone thickness and interproximal root distance are key anatomical determinants of treatment efficacy.