Effects of heterologous type I collagen injections following orthodontic premolar extractions: A pilot split-mouth study
Federica Pellitteri, Francesca Cremonini, Luca Brucculeri, Carlotta Preite, Luca LombardoObjectives:
This randomized clinical trial investigated the effects of heterologous type I collagen injections, applied as a treatment for orthodontic patients undergoing premolar extractions, compared with saline on soft-tissue healing, orthodontic extraction space closure, and post-extraction pain perception.
Material and Methods:
Ten patients (mean age 27.5 ± 7.6 years) undergoing fixed multibracket treatment with bilateral premolar extractions were enrolled. Each patient received heterologous type I collagen injections on one extraction site and saline on the contralateral site, randomly assigned, following a split-mouth design that allowed each patient to serve as their own control. Collagen or saline was injected submucosally at baseline and subsequent two follow-up visits, for a total of 3 injections every 2 weeks. Intraoral scans were performed to measure extraction space closure using linear digital analysis (Rhinoceros software) at each appointment. At 6 weeks, 5-mm punch biopsies were harvested and processed for histological and immunohistochemical analysis. Post-extraction pain was assessed using a 10-point Visual Analog Scale, with patients recording separate scores for each side 2 weeks after extractions.
Results:
Collagen injections did not significantly accelerate extraction space closure compared with saline at 6 weeks. However, pain perception was significantly lower at collagen-treated sites, indicating a beneficial effect on post-operative discomfort. Qualitative histological assessment revealed more organized connective tissue and advanced collagen fiber maturation in collagen-treated sockets. Immunohistochemistry (CD31 and smooth muscle actin) confirmed vascular structures in all samples, with no adverse reactions observed.
Conclusions:
Heterologous type I collagen injections, applied as a treatment for orthodontic extraction sites, reduced post-extraction pain and promoted qualitatively more advanced soft-tissue organization, although they did not significantly influence orthodontic space closure over 6 weeks.