Successful bone augmentation relies on primary wound closure. Labial frenum is a soft tissue that connects the lip to alveolar mucosa or gingiva. However, frenum may exert biomechanical forces to the wound edge, causing wound instability. The aim of this study is to (1) review the frenum composition and classifications; (2) understand the significance of frenum in wound stability upon bone regeneration. An electronic search was conducted through the three online databases together with manual search on studies published until September 2022. A total of 300 articles were identified and 11 studies were included in this review. Two of the included six studies discovered that 35-37.5% of the labial frenum had muscle fibers. Other studies showed that labial frenum was mainly composed of connective tissue with elastic fibers. There are two widely used classifications for frenum based on morphology and position of attachment. No studies specifically evaluated the impact of frenum on bone regeneration. Frenum location intercorrelated with the amount of keratinized tissue, which could influence wound stability. A modified frenum classification for the edentulous ridge and a decision diagram to manage the frenum is proposed for research and evidenced practice.
