Continuous intra-sinus bone regeneration after nongrafted sinus lift with a PLLA mesh plate device and dental implant placement in an atrophic posterior maxilla: a case report

BACKGROUND: Sinus lift is a bone augmentation procedure that improves the alveolar crest height in an atrophic posterior maxilla. However, the regenerated bone volume can vary and generally has a tendency to decrease after sinus operation. This article describes nongrafted maxillary sinus lift using a bioresorbable unsintered hydroxyapatite combined with poly l-lactide (HA/PLLA) mesh plate device and dental implant placement in an atrophic posterior maxilla, after which continuous bone gain was observed around the implant apex during a postoperative follow-up period of 3 years. CASE PRESENTATION: A 60-year-old healthy female was referred to our department for dental implant therapy in the right posterior maxilla. Clinical examination revealed that the maxilla was edentulous from the right first premolar to the second molar region. Radiographically, atrophy of the maxillary alveolar ridge in the same tooth site was observed. Sinus membrane elevation and simultaneous implant placement were performed through the lateral approach. HA/PLLA mesh was utilized to maintain space under the elevated sinus membrane and as a fixation device to replace the bone window. Six months later, new bone was generated in the secluded space maintained under the elevated sinus membrane. When observed 42 months after the implant insertion, bone volume around the implant apex had increased in vertical direction under the HA/PLLA mesh plate device, and there was continuous bone formation in the sinus over time. CONCLUSION: This nongrafted sinus lift procedure using an HA/PLLA mesh device attained predictable bone formation. Stable membrane elevation by an HA/PLLA device might induce long-term, continuous bone formation in the sinus.