A 60-year-old healthy female, who desired dental implant therapy in the right molar region of the maxilla, was referred to the Department of Oral and Maxillofacial Surgery. Clinical examination revealed an edentulous maxilla from the right first premolar to the second molar region. Panoramic radiography showed atrophy of the maxillary alveolar ridge in the same site (Fig. 1), and the need for sinus augmentation was confirmed by computed tomography (CT). The patient was informed of the details of the treatment protocol, in particular the sinus surgery, and she consented to participate. A written consent was obtained.

Maxillary sinus lift and simultaneous implant placement were implemented by sinus membrane elevation using an HA/PLLA mesh device without grafting materials. Using a piezoelectric device (Piezosurgery®; Mectron Medical Technology, Carasco, Italy), osteotomy was performed in the lateral sinus wall of the right posterior maxilla (Fig. 2). After the removal of the bone window, the membrane was carefully elevated from the sinus floor and two implants (Replace Select™ Tapered, TiUnite™; Nobel Biocare AB, Göteborg, Sweden) were inserted through the maxillary ridge into the space created under the elevated sinus membrane (Fig. 3). Subsequently, the bone window was replaced and measures for maintaining the space under the elevated sinus membrane were taken using an HA/PLLA mesh plate device (Super FIXSORB®-MX, Takiron Co., Ltd., Kobe, Japan). To support the membrane, the device was bent in L form in warm water at 75 °C and attached to the bone window (Fig. 4a, b). Using the mesh plate, the sinus membrane was lifted, and bone window was fixed to the sinus wall using two short HA/PLLA screws (Fig. 5). The abutment was connected 6 months after the sinus surgery. During the follow-up periods after the first and second surgeries, wound healing was uneventful and no intra-sinus problem was observed. Four months after the abutment connection, screw-retained implant prosthesis was fabricated and loaded. Pre- and postoperative alveolar crest heights were evaluated using CT reformatted using Simplant Pro™ software (Materialise Dental NV, Leuven, Belgium) (Figs. 6a–c and 7a–c). Postoperative radiographs were taken immediately and at 6 and 42 months following implant insertion. Six months after implant insertion, the implant was entirely embedded in the newly formed bone under the HA/PLLA mesh device surrounded by soft tissue density (Figs. 6b and 7b). Additional bone formation in vertical direction was noted in the space under the HA/PLLA mesh plate device 6 to 42 months after implant insertion. At 42 months after implant insertion, continuous increase of bone volume above the implant apex was confirmed without excessive marginal bone loss around the implant neck (Figs. 6c and 7c). It has now been more than 3 years since the installation of the permanent restoration, and no problems have been observed (Fig. 8).