In our recent study, we successfully demonstrated the safety and efficacy of ATB powder in ARP procedures. We are the first to report clinical, radiographical, and histological data demonstrating favourable defect fills of EDS-class 3–4 postextraction sockets utilizing an autogenous tooth-derived bone grafting material.
Bone substitute materials may be used alone for ARP: deproteinized bovine bone material , demineralized freeze-dried bone allograft , hydroxyapatite crystals , bioglass , polylactide and polyglycolide sponge  have been proposed as osteoconductive scaffolds. Several types of membranes have been suggested for alveolar ridge preservation purposes: extended polytetrafluoroethylene membrane , bioabsorbable membrane from lactide and glycolide polimers , dense polytetrafluoroethylene . In addition, membranes may be combined with bone grafting materials as well: dense polytetrafluoroethylene membrane and grafting material , collagen membrane and freeze-dried bone graft , xenogenic bone substitutes combined with a collagen barrier membrane [23,24]. Although there are many surgical methods that focus on maintaining hard tissue volume, none of them can be defined as ‘gold standard’, since post-extraction ridge resorption cannot be eliminated totally according to literature [5,25]. The Bonmaker® device is feasible for grinding, disinfecting, and preparing extracted teeth to obtain ATB, a ready-to use particulate grafting material. ATB processing allows for producing both particulate and block grafts. Based on previous literature data describing the clinical handling and application of biomaterials in ARP procedures, particulate ATB powder and ATB blocks may act as a resorbable scaffold and space maintaining device to facilitate the healing of acute and chronic alveolar defects [6,8].
During our current study, the ATB powder preparation procedure took approximately 30 min, including pre-cleaning with diamond-coated burs and removal of restorations. While the device was in operation, the thorough removal of inflammatory tissues from the alveoli, as well as harvesting FGG’s from patients’ hard palate could be performed in a time-efficient manner. ATB exhibited excellent handling properties. After the preparation, the graft material became wet and sticky, which made it comfortable to use. To ensure the compaction of the grafting material inside the alveolar socket, osteotomes were applied. Wound healing was uneventful, major adverse events were not observed in any of the treated cases. In two out of the nine extraction sites, minor adverse events occurred: the epithelial layer of the FGG partially necrotized and had to be removed after one week. Even in these cases, after the removal of the necrotized epithelium, the grafting material was fully covered with connective tissue, indicating that FGG would facilitate wound healing by protecting the underlying grafted area. Secondary intention wound healing resulted in new keratinized tissue formation and complete graft coverage at 3 weeks postoperatively. 6 months after ARP, re-entry procedure was performed in order to place implants and harvest core biopsies from the preserved sites. According to Schropp et al. 2003, in the first 12 months after tooth extraction, on average less than 1 mm vertical remodelling occurs (+ 0.4 mm palatally, − 0.8 mm buccally). Due to ridge atrophy, as much as 50% of the original width is lost (6.1 mm on average) during spontaneous healing. In our study, similarly no vertical shrinkage was observed. Moderate loss of horizontal dimension of the alveolar crest was detectable at all sites, however, the shrinkage was minimal (15% on average), considering the fact that all the sites were previously qualified as EDS class 3–4 defects, exhibiting compromised healing capacity, representing a biological challenge for clinicians in terms of complete defect reconstruction. In some cases, supracrestal graft particles were maintained until re-entry, nevertheless, this cannot be considered as vertical socket augmentation, since supracrestal ATB parts were not always as mature as the subcrestal proportion of the reconstructed area.
The placement of fixtures in native bone was possible after core biopsy harvesting in all cases. Nevertheless, to compensate for the horizontal dimension loss for aesthetically favourable outcomes, contour augmentation was carried out in the buccal aspect in 6 out of 9 implant sites. The osseointegration of the inserted implants was successful, implant-fixed partial dentures were delivered after implant uncovery.
According to a systematic review, histological analysis of alveolar ridge preservation procedures revealed inferior hard tissue quality compared to native bone following all currently known approaches . Cardaropoli et al. performed socket preservation with bovine bone mineral combined with 10% collagen and found 26.6% of newly formed bone with 18.5% grafting material surrounded by 55% connective tissue . Barone et al. carried our ARP with a corticocancellous porcine graft and a resorbable collagen membrane. After at least 7 months of healing, core biopsies were harvested from the extraction sites: histomorphometrically they found 35.5% bone, 29.2% grafting material and 36.6% connective tissue . Artzi et al. used porcine-based grafting material for socket preservation, and after 9 months of healing, re-entry procedure was performed, core biopsies were harvested. During histomorphometrical evaluation, the authors found 46.3% average bone fraction, 30.8% grafting material, and 22.9% connective tissue part28. Comparing our results with literature data reporting on limited graft remodeling in newly formed hard tissues following ARP, the histological evaluation in our current study confirmed an excellent remodeling of the ATB material. As shown by the histomorphometric analysis, the mean value of newly formed bone was 56%, which was significantly higher compared to data reported in literature. Six samples out of nine yielded more than 50% of new bone, which indicated exceptional tissue quality. In the harvested samples, only 7% of non-remodelled ATB material was observed on average, which indicated a more rapid turnover of graft particles compared to literature data reporting on xenogeneic materials used in ARP. A mean of 37% connective tissue was found in the samples, this was in line with previous observations following ARP with particulate grafting materials. Histomorphometrical analysis was performed in the complete biopsy area. In further studies, it is necessary to evaluate the graft integration pattern differences along the apicocoronal axis of core biopsies.
Compared to literature data, the significant amount of newly formed bone and the low amount of non-remodelled graft particles yielded a more favorable quality of hard tissues, confirmed by direct assessment during re-entry. ATB was capable of osteoinduction and osteoconduction, and newly formed hard tissues resembled native bone structurally, both intraoperatively and histologically. Moreover, the immediate application of ATB as an autogenous grafting material was cost- and time-efficient for the patient. The application of ATB with FGG coverage proved to be an ARP technique, which may limit post-extraction alveolar bone loss and, at the same time, provide favorable hard- and soft tissue quality.