Gingival fenestration is a relatively uncommon soft tissue lesion in which the root apex is exposed in the oral environment after the destruction of the overlying buccal bone plate and mucosa. At present, no clear etiology or treatment guidelines exist for gingival fenestration. This article reports three successfully treated cases of gingival fenestration associated with chronic periapical infection and can help contribute to treatment guidelines for gingival fenestration. All cases were treated with apicoectomy in conjunction with a connective tissue graft (CTG), and the first steps of each case were as follows: endodontic therapy with root-end resection and retrograde filling, then regenerative surgical therapy. However, slightly different regenerative treatment methods were used during the operation according to the different patient conditions. In Case 1, gingival fenestration in the mandibular left first premolar was treated using a xenograft and CTG. In Case 2, gingival fenestration in the maxillary left lateral incisor was treated using advanced platelet-rich fibrin (A-PRF) and CTG. In Case 3, gingival fenestration in the mandibular left second premolar was treated using CTG. Endodontic treatment was combined with periodontal surgery to achieve predictable results. After 13 to 25 months of follow-up, all cases showed well-healed gingival fenestrations and no discomfort. These three cases show the possibility of using apical excision combined with a CTG and/or bone graft/A-PRF in the treatment of gingival fenestration. Reporting these three cases may help advance the field of gingival fenestration treatment.