Bone morphogenetic protein-2 loaded poly(D,L-lactide-co-glycolide) microspheres enhance osteogenic potential of gelatin/hydroxyapatite/ß-tricalcium phosphate cryogel composite for alveolar ridge augmentation.

BACKGROUND/PURPOSE: Sufficient bony support is essential to ensure the success of dental implant osseointegration. However, the reconstruction of vertical ridge deficiencies is still a major challenge for dental implants. This study introduced a novel treatment strategy by infusing poly(D,L-lactide-co-glycolide) (PLGA) microspheres encapsulating bone morphogenetic protein-2 (BMP-2) within a gelatin/hydroxyapatite/ß-tricalcium phosphate (gelatin/HA/ß-TCP) cryogel composite to facilitate supra-alveolar ridge augmentation. METHODS: The gelatin scaffold was crosslinked using cryogel technique, and HA/ß-TCP particles were mechanically entrapped to form the gelatin/HA/ß-TCP composite. Co-axial electrohydrodynamic atomization technology was used to fabricate PLGA microspheres encapsulating BMP-2. The composites of gelatin/HA/ß-TCP alone, with infusion of BMP-2 solution (BMPi) or microspheres (BMPm), were fixed on rat mandibles using a titanium mini-implant for 4 weeks, and the therapeutic efficiency was evaluated by micro-computed tomography, bone fluorochrome, and histology. RESULTS: The gelatin/HA/ß-TCP composite was homogenously porous, and BMP-2 was sustained release from the microspheres without initial burst release. Ridge augmentation was noted in all specimens treated with the gelatin/HA/ß-TCP composite, and greater bone deposition ratio were noted in Groups BMPi and BMPm. Compared with Group BMPi, specimens in Group BMPm showed significantly greater early osteogenesis and evident osseointegration in the supra-alveolar level. CONCLUSION: BMP-2 loaded PLGA microspheres effectively promoted osteogenic potential of the gelatin/HA/ß-TCP composite and facilitated supra-alveolar ridge augmentation in vivo.

Evaluation of 660 nm LED light irradiation on the strategies for treating experimental periodontal intrabony defects.

This study aims to investigate the therapeutic value of 660 nm light-emitting diode (LED) light irradiation on the strategies for treating experimental periodontal intrabony defects in vivo. Large-sized periodontal intrabony defects were created bilaterally on the mesial aspect of the maxillary second molars of 48 Sprague-Dawley rats, and the rats were equally divided into four treatment groups with primary wound intention (n = 6/treatment/time point), including open flap debridement alone (OD), barrier membrane alone (MB), xenograft alone (BG), and xenograft plus barrier membrane (MG). Each group received daily 0 or 10 J/cm(2) LED light irradiation. The animals were sacrificed after 1 or 4 weeks. The treatment outcome was evaluated by gross observation of wound dehiscence and healing, micro-CT imaging for osteogenesis, and histological assessments for inflammatory cell infiltration and periodontal reattachment. With LED light irradiation, the extent of wound dehiscence was reduced, wound closure was accelerated, epithelial downgrowth was prevented, inflammation was reduced, and periodontal reattachment was promoted in all treatment strategies. Significant reduction of inflammation with LED light irradiation was noted at 1 week in the groups BG and MG (p < 0.05). Osteogenesis was significantly promoted only in the group OD at both time points (p < 0.05). Our study showed that 660 nm LED light accelerates mucoperiosteal flap healing and periodontal reattachment. However, the enhancement of osteogenesis appeared to be limited while simultaneously treating with a barrier membrane or xenograft.

Classification of the implant-ridge relationship utilizing the MobileNet architecture.

Background/purpose: Proper implant-ridge classification is crucial for developing a dental implant treatment plan. This study aimed to verify the ability of MobileNet, an advanced deep learning model characterized by a lightweight architecture that allows for efficient model deployment on resource-constrained devices, to identify the implant-ridge relationship. Materials and methods: A total of 630 cone-beam computerized tomography (CBCT) slices from 412 patients were collected and manually classified according to Terheyden's definition, preprocessed, and fed to MobileNet for training under the conditions of limited datasets (219 slices, condition A) and full datasets (630 cases) without and with automatic gap filling (conditions B and C). Results: The overall model accuracy was 84.00% in condition A and 95.28% in conditions B and C. In condition C, the accuracy rates ranged from 94.00 to 99.21%, with F1 scores of 89.36-100.00%, and errors due to unidentifiable bone-implant contact and miscellaneous reasons were eliminated. Conclusion: The MobileNet architecture was able to identify the implant-ridge classification on CBCT slices and can assist clinicians in establishing a reliable preoperative diagnosis and treatment plan for dental implants. These results also suggest that artificial intelligence-assisted implant-ridge classification can be performed in the setting of general dental practice.

Deep learning for the identification of ridge deficiency around dental implants.

OBJECTIVES: This study aimed to use a deep learning (DL) approach for the automatic identification of the ridge deficiency around dental implants based on an image slice from cone-beam computerized tomography (CBCT). MATERIALS AND METHODS: Single slices crossing the central long-axis of 630 mandibular and 845 maxillary virtually placed implants (4-5 mm diameter, 10 mm length) in 412 patients were used. The ridges were classified based on the intraoral bone-implant support and sinus floor location. The slices were either preprocessed by alveolar ridge homogenizing prior to DL (preprocessed) or left unpreprocessed. A convolutional neural network with ResNet-50 architecture was employed for DL. RESULTS: The model achieved an accuracy of >98.5% on the unpreprocessed image slices and was found to be superior to the accuracy observed on the preprocessed slices. On the mandible, model accuracy was 98.91 ± 1.45%, and F1 score, a measure of a model's accuracy in binary classification tasks, was lowest (97.30%) on the ridge with a combined horizontal-vertical defect. On the maxilla, model accuracy was 98.82 ± 1.11%, and the ridge presenting an implant collar-sinus floor distance of 5-10 mm with a dehiscence defect had the lowest F1 score (95.86%). To achieve >90% model accuracy, ≥441 mandibular slices or ≥592 maxillary slices were required. CONCLUSIONS: The ridge deficiency around dental implants can be identified using DL from CBCT image slices without the need for preprocessed homogenization. The model will be further strengthened by implementing more clinical expertise in dental implant treatment planning and incorporating multiple slices to classify 3-dimensional implant-ridge relationships.

Preclinical alveolar ridge preservation using small-sized particles of bone replacement graft in combination with a gelatin cryogel scaffold.

BACKGROUND: Particulate anorganic bovine bone matrix (ABBM) is extensively used for alveolar ridge preservation (ARP). This study evaluates the potential of ABBM/gelatin cryogel scaffold of regular (250 to 1,000 µm) and small (50 to 100 µm) particles for ARP. METHODS: ABBM was either condensed in a gypsum ring to simulate filling of ABBM in a defect or incorporated into a gelatin cryogel scaffold to disperse ABBM. Condensed regular-sized or small-sized ABBM (rABBM or sABBM) (± bone morphogenetic protein [BMP]-2) were subcutaneously implanted in rats to evaluate biocompatibility and osteogenic potential. Experimental extraction sockets were surgically created on the maxillary ridges of rats and were unfilled (control), filled with rABBM/gelatin, or sABBM/gelatin cryogel scaffold. The socket fill and dimensional changes of the ridge were evaluated by microcomputed tomography imaging and histology. RESULTS: Condensed sABBM showed acceptable biocompatibility but significantly lower interparticle distance (IPD) and porosity (P < 0.001) compared with rABBM, whereas rABBM/gelatin and sABBM/gelatin cryogel scaffold showed similar IPD and porosity. Osteogenesis took place in rABBM/gelatin and sABBM/gelatin-treated extraction sockets showed osteogenesis at 8 weeks and had increased ridge width and reduced ridge discrepancy compared with the control sites. sABBM/gelatin scaffold significantly increased socket fill and reduced ridge discrepancy at 4 weeks, increased ridge width at 8 weeks, and reduced buccal ridge height resorption at both 4 and 8 weeks (P < 0.05 for all). CONCLUSIONS: Osteoconductivity was suppressed in condensed sABBM, even after adding BMP-2. By dispersing sABBM in a gelatin cryogel scaffold, sABBM/gelatin showed a greater potential in promoting socket fill, reducing buccal ridge atrophy, and providing equivalent ridge stability compared with rABBM/gelatin.

PDGF-metronidazole-encapsulated nanofibrous functional layers on collagen membrane promote alveolar ridge regeneration.

This study aimed to develop a functionally graded membrane (FGM) to prevent infection and promote tissue regeneration. Poly(l-lactide-co-d,l-lactide) encapsulating platelet-derived growth factor (PDLLA-PDGF) or metronidazole (PDLLA-MTZ) was electrospun to form a nanofibrous layer on the inner or outer surface of a clinically available collagen membrane, respectively. The membrane was characterized for the morphology, molecule release profile, in vitro and in vivo biocompatibility, and preclinical efficiency for alveolar ridge regeneration. The PDLLA-MTZ and PDLLA-PDGF nanofibers were 800-900 nm in diameter, and the thicknesses of the functional layers were 20-30 µm, with sustained molecule release over 28 days. All of the membranes tested were compatible with cell survival in vitro and showed good tissue integration with minimal fibrous capsule formation or inflammation. Cell proliferation was especially prominent on the PDLLA-PDGF layer in vivo. On the alveolar ridge, all FGMs reduced wound dehiscence compared with the control collagen membrane, and the FGM with PDLLA-PDGF promoted osteogenesis significantly. In conclusion, the FGMs with PDLLA-PDGF and PDLLA-MTZ showed high biocompatibility and facilitated wound healing compared with conventional membrane, and the FGM with PDLLA-PDGF enhanced alveolar ridge regeneration in vivo. The design represents a beneficial modification, which may be easily adapted for future clinical use.