Alveolar ridge preservation using biomaterials is a well-established approach to counteract post-extraction bone resorption and optimize conditions for implant placement. However, most studies rely only on a single evaluation method and thereby risk overlooking essential aspects of alveolar regeneration. This preliminary analysis aimed to assess alveolar ridge preservation outcome using a multimodal approach combining histomorphometric, radiological, and image-based visualization methods. Twenty out of a planned 60 patients per group from an ongoing randomized controlled clinical trial were included. Patients were allocated to alveolar ridge preservation with a bone substitute material (BSM), a collagen-based material, a combination of both, or natural healing as control. Outcomes included CBCT-based volumetric analysis, histomorphometry, and primary implant stability via ISQ. Mineralized bone volume was significantly better preserved in bone substitute material groups compared to other groups, with BSM combined with collagen yielding the highest values. Histomorphometrically determined hard tissue fractions and implant stability were comparable across groups. Notably, CBCT-based visualization revealed non-ossified hypodense regions, so-called cavitations or covered socket residuum (CSR) within the former extraction sockets across all groups, independent of the biomaterial applied. BSM-based alveolar ridge preservation, particularly combined with a collagen membrane, most effectively maintained mineralized bone volume after extraction. Beside volumetric benefits, this preliminary in-dept analysis of the first part of the trial highlights cavitations/CSRs as a potentially underrecognized feature of post-extraction healing. Integrating quantitative with qualitative visualization-based assessments provides a more complete understanding of alveolar bone regeneration.

Background/Objectives: After extraction, the crest may close before the socket has mineralised, leaving a covered socket residuum that may enclose the tissue lining the socket. We examined the socket wall histologically at the moment of extraction and compared it with the periapical region and the socket walls on preoperative cone-beam computed tomography (CBCT). Methods: Retrospective single-centre study of teeth extracted by one surgeon for a clinical indication in routine care. Before decortication according to the ARENA-Protocol^® (Alveolar Ridge Epithelialization after Non-viable Bone Debridement and Augmentation), a trephine core was taken along the long axis of the socket wall; soft tissue was submitted when present. Each specimen received a leading diagnosis from a predefined hierarchy. Results: Sixty-six specimens from 41 sockets in 23 patients were examined. Thirty-eight sockets (92.7%) were altered. Bone showed mainly chronic inflammation and marrow fibrosis, soft tissue mainly florid inflammation. The radiographic lesion lay periapically and was visible on CBCT and its three-dimensional visualisation, whereas the lateral wall from which the core was taken showed no distinct change on either and was nevertheless altered, also in all three sockets without a periapical finding. All 14 root-filled and 24 of 27 non-root-filled sockets were altered. Conclusions: In this cohort, the socket wall was altered at extraction in almost every case, and the alteration along the long axis of the socket was detected only histologically. If the crest closes over such a wall, a residuum may enclose altered tissue. Controlled studies are needed to test this.

Background/Objectives: After tooth removal the crest may close before the socket has mineralised, leaving a covered socket residuum (CSR). Third molars are usually removed in young patients, often prophylactically. We examined what former third molar sites contain years later. Methods: Retrospective single-centre study of bone removed at revision of a radiologically diagnosed CSR at former third molar sites, consisting of the bone lid covering the residuum and, where labelled separately, tissue from its depth. For every section the routine pathology report was coded for a leading finding, and the cells were classified independently by whole-slide AI analysis without knowledge of the report. Results: Eighty-three sections from 28 patients (median age 54 years) were analysed. Fifty-one (61.4%) carried a distinguishing finding (53.0% without haematopoietically active marrow), most often marrow fibrosis (14.5%), granulocytic inflammation or osteomyelitis (13.3%) and lymphoplasmacytic infiltrate (10.8%). Of 24 patients with more than one section, 13 showed different findings in different sections. Fibroblasts and inflammatory cells were inversely related (r = −0.979), and the diagnoses formed a gradient from fibroblast-rich avital bone and unremarkable marrow to lymphocyte-rich inflammation (Holm-adjusted p ≤ 0.0065 for fibroblasts, lymphocytes and neutrophils). Conclusions: In this cohort, more than half of the sections from former third molar sites were histopathologically altered, with findings that varied within the same patient. Third molar removal is bone surgery requiring asepsis, removal of the follicle and debridement of the socket, and filling the socket to prevent a residuum deserves controlled evaluation.