The influence of flap design on the relevance of biomaterials in regenerative periodontal surgery

BACKGROUND: The aim of this systematic review was to explore whether the benefits of biomaterials in periodontal regenerative/reconstructive surgery are affected by the type of flap employed. The study addresses the existing gap in the evidence to substantiate the beneficial effect of minimal invasive periodontal surgical approach compared to a conventional access flap (AF) surgery for the treatment of intrabony periodontal defects. METHODS: Electronic search on Embase, Medline, Cochrane, Scopus, and manual search were performed to identify suitable randomized controlled trials on periodontal regenerative/reconstructive surgery. The Cochrane Collaboration's tool was used to assess the risk of bias. Papers were divided according to flap design into AFs, papilla preservation flaps (PPFs), and single-flap variants (SFVs). Meta-analyses were carried out to assess the effect of the added biomaterial compared with controls on probing pocket depth (PPD) and clinical attachment level (CAL), subdivided by flap design. RESULTS: Of the 1311 papers initially identified, 523 underwent full-text screening, and 29 publications representing 28 studies were ultimately included. In Group 1 (AFs, n = 6), the meta-analysis revealed a statistically significant additional effect of biomaterials on improving CAL outcomes at 12 months, with an additional 2.46 mm CAL gain compared to control (95% confidence interval [CI]: 0.37-4.56, p = 0.02). In Group 2 (PPFs, n = 19), biomaterials provided a statistically significant benefit compared to PPF alone, with an additional 1.86 mm PPD reduction (95% CI: 0.29-3.42, p = 0.02) and 2.15 mm CAL gain (95% CI = 0.59-3.70, p = 0.01) at 12 months. In Group 3 (SFVs, n = 3), there was no statistically significant difference between the minimally invasive flap alone and its combination with biomaterials in terms of PPD reduction or CAL gain at 12 months. CONCLUSION: This systematic review suggests that SFVs may reduce the need for biomaterials due to their minimally invasive nature. The limited number of studies included in the SFV group and the high heterogeneity represent limitations of this review. It is still unclear whether flap design alone or the addition of biomaterials has a greater impact on clinical outcomes such as PPD reduction and CAL gain. The relative importance of biomaterials in periodontal regeneration requires further investigation. PLAIN LANGUAGE SUMMARY: This study reviewed existing clinical trials to understand whether the way gum tissue is lifted during surgery-known as flap design-affects the need for added materials (biomaterials) when treating bone loss caused by gum disease. Biomaterials are often used to support healing in regenerative periodontal surgery. However, newer surgical techniques that involve smaller trauma may reduce the need for these materials. The review grouped studies into 3 types of flap designs: traditional access flaps, papilla preservation flaps, and single-flap variants (a minimally invasive technique). It found that using biomaterials improved outcomes when combined with traditional or papilla-preserving flaps. In contrast, no significant benefit was observed when biomaterials were added to single-flap variants. These findings suggest that with certain minimally invasive techniques, effective healing may occur even without biomaterials. However, only a few studies examined single-flap variants, and results varied across studies, meaning that more research is needed. Understanding when biomaterials are truly necessary can help reduce treatment costs, improve healing, and guide better surgical choices for patients with advanced gum disease.