Herein, we present a case of oroantral communication that was to be treated with clinical examination, tomography, and prototyping. A patient presented with oroantral communication with purulent exudation for 4 months, since the displacement of the dental implant and O-ring component to the maxillary sinus. Tomographic examination and prototyping revealed a 5 mm bone gap. The patient underwent local washes and antibiotic therapy. After local palpation, a bone defect detected by prototyping was suspected to be greater than that observed. For the surgery, a communication tunnel was made, and the bone defect was found to be 12 mm in diameter. A pedicle flap was raised on the palate, followed by sliding and suturing. No complications were observed during the postoperative period, and the suture was removed after a week. Four months later, communication did not resume, and the patient did not complain of pain, foul smelling, or purulent discharge and was satisfied with the outcome. The findings of this case suggest that the lateral sliding flap can be used as an efficient technique for closing oroantral communications. An accurate clinical examination is a critical tool that can be used instead of tomography and prototyping, which can be misleading.