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Aim: This study investigated the adjunctive effect of polydeoxyribonucleotide (PDRN) on bone formation in alveolar ridge preservation (ARP) sockets. Materials and Methods: Both mandibular second, third and fourth premolars of eight beagle dogs were randomly divided into ARP and ARP/PDRN groups. Following tooth extraction, ARP procedures were conducted using collagenized alloplastic graft material and bilayer collagen membrane soaked with normal saline (ARP group) or PDRN (ARP/PDRN group) for 10 min before application. Both groups were also randomly allocated to 2‐, 4‐ or 12‐week healing subgroups. The primary endpoint of this study was to compare histomorphometric differences between ARP and ARP/PDRN. The secondary endpoints of this study were to compare micro‐CT analysis and three‐dimensional volumetric measurement between the two groups. Results: In the histomorphometric analysis, the ARP/PDRN group exhibited greater new bone formation at coronal, middle and total position compared with the ARP group at 2‐week healing. The number of newly formed blood vessels was higher in the ARP/PDRN group than in the ARP group at 2‐ and 4‐week healing. In micro‐CT analysis, the mean new bone volume/total bone volume between ARP and ARP/PDRN was statistically significant at 2‐week healing. Ridge volume alterations were significantly decreased in the ARP/PDRN group during entire healing time compared with the ARP group, especially on the buccal side. Conclusions: The application of PDRN in ARP might provide additional benefits for early bone regeneration and maintenance of buccal ridge volume. [ABSTRACT FROM AUTHOR]

Background: Guided bone regeneration (GBR) is the most widely used technique for overcoming the deficiency of alveolar bone. However, the progression of peri‐implantitis in regenerative and pristine bone sites has not been fully investigated. The aim of this study is to compare experimental peri‐implantitis around implants placed in pristine bone and GBR sites. Methods: Bilateral mandibular first molars were extracted from six beagle dogs, and standardized horizontal ridge defect was simultaneously created at predetermined site in unilateral mandible. After 8 weeks, guided bone regeneration procedure was conducted at the defect site. After 16 weeks, implants (ϕ 3.6×8.0 mm) were placed at both extracted sites. This study included 3 months of active breakdown and another 3 months of spontaneous progression period. Radiographs were taken at each phase and specimens were obtained for histological, immunohistochemical, and polarized light microscopic analysis. Results: Marginal bone loss around implant did not show the significant differences between pristine bone and GBR sites during spontaneous progression period. In immunohistochemical analysis, inflammatory and immune‐related cells were predominantly detected in peri‐implantitis‒affected area rather than unaffected area. In the polarized light microscopic analysis, substantial reductions in the amount and thickness of collagen fibers were observed in peri‐implantitis‒affected area compared with unaffected tissues. However, there were no significant differences in histological, immunohistochemical, polarized light microscopic outcomes between pristine bone and GBR sites. Conclusion: Previous hard tissue grafting at the implant sites did not affect experimental peri‐implantitis and exhibited similar radiographic, histological, immunohistochemical, and polarized light microscopic outcomes compared with those of pristine bone sites. [ABSTRACT FROM AUTHOR]

Background: Three- dimensional (3D) technology has been suggested to overcome several limitations in guided bone regeneration (GBR) procedures because 3D-printed scaffolds can be easily molded to patient-specific bone defect site. This study aimed to investigate the effect of 3-D printed polylactic acid (PLA) scaffolds with or without hyaluronic acid (HA) in a rabbit calvaria model.Methods: A calvaria defect with a diameter of 15 mm was created in 30 New Zealand white rabbits. The rabbits were randomly allocated into three groups including no graft group (control, n = 10), 3D printed PLA graft group (3D-PLA, n = 10), and 3D printed PLA with hyaluronic acid graft group (3D-PLA/HA, n = 10). Five animals in each group were sacrificed at 4 and 12 weeks after surgery. Microcomputed tomography and histologic and histomorphometric analyses were performed.Results: Over the whole examination period, no significant adverse reactions were observed. There were no statistically significant differences in bone volume (BV) /tissue volume (TV) among the three groups at 4 weeks. However, the highest BV/TV was observed in the 3D-PLA/HA group at 12 weeks. The new bone area for control, 3D-PLA, and 3D-PLA/HA showed no statistical differences at 4 weeks. However, the value was significantly higher in the 3D-PLA and 3D-PLA/HA groups compared to the control group at 12 weeks.Conclusion: The 3D printed PLA scaffolds was biocompatible and integrated well with bone defect margin. They were also provided the proper space for new bone formation. Therefore, 3D printed PLA/HA might be a potential tool to enhance bone augmentation. [ABSTRACT FROM AUTHOR]

The cover image is based on the Original Article The adjunctive effect of polydeoxyribonucleotide on bone formation in alveolar ridge preservation: A pre‐clinical in vivo study by Young‐Chang Ko et al., https://doi.org/10.1111/jcpe.13988. [ABSTRACT FROM AUTHOR]