Vertical ridge augmentation in the posterior mandible is a technique-sensitive procedure that requires adequate anatomical knowledge and precise surgical skills to minimize the risk of complications. One of the most important but also challenging aspects of the surgical technique is proper flap management to allow for passive flap closure and reduce the chances of postoperative complications affecting deep anatomical spaces. This article presents a detailed description of a novel lingual flap advancement technique and its validation via a split-mouth, comparative study using a cadaver model. A total of 12 fresh cadaver heads presenting bilateral posterior mandibular edentulism were selected. Sides were randomized to receive a classic lingual flap release technique (control) or the modified technique presented here, which involves the intentional preservation of the mylohyoid muscle attachment to the mandible. Vertical flap release was measured at three different zones using standard forces. The mean difference between the test and control group in zones I (retromolar pad area), II (middle area), and III (premolar area) was 8.273 ± 1.794 mm (standard error of the mean [SEM] = 0.5409 mm), 10.09 ± 2.948 mm (SEM = 0.8889 mm), and 10.273 ± 2.936 mm (SEM = 0.8851 mm), respectively, reaching very strong statistical significance (P < .0001) in all three zones.