Open extraction sockets following inward fragmentation of partially erupted mandibular third molars may compromise the hard tissue regeneration and lead to postoperative complications. In the case report, we present socket preservation to seal the open alveolous without flap displacement. A female patient aged 22, presented for removal of a partially erupted M3M was operated on via occlusal inward fragmentation under magnifying endoscopic vision. Critical nerve structures were identified and protected before socket preservation with resorbable in situ hardening TCP particles was performed. The alveolar bone site healed uneventful, panoramic and cross-sectional conebeam reformats confirmed an complete hard tissue maintanence. Endoscopically assisted inward fragmentation combined with socket preservation leads to the maintenance of adjacent hard tissues without need for flap transposition in complex anatomical sites.