The effect of hard-type crosslinked hyaluronic acid with particulate bone substitute on bone regeneration: positive or negative?

PURPOSE: The role of hard-type crosslinked hyaluronic acid (HA) with particulate bone substitutes in bone regeneration for combined inlay-onlay grafts has not been fully investigated. We aimed to evaluate the effect of hard-type crosslinked HA used with bone substitute in terms of new bone formation and space maintenance. METHODS: A 15-mm-diameter round defect was formed in the calvaria of 30 New Zealand White rabbits. All animals were randomly assigned to 1 of 3 groups: the control group (spontaneous healing without material, n=10), the biphasic calcium phosphate (BCP) graft group (BCP, n=10), and the BCP graft with HA group (BCP/HA, n=10). The animals were evaluated 4 and 12 weeks after surgery. Half of the animals from each group were sacrificed at 4 and 12 weeks after surgery. Samples were evaluated using micro-computed tomography, histology, and histomorphometry. RESULTS: The BCP group showed higher bone volume/tissue volume (BV/TV) values than the control and BCP/HA groups at both 4 and 12 weeks. The BCP and BCP/HA groups showed higher bone surface/tissue volume (BS/TV) values than the control group at both 4 and 12 weeks. The BCP group showed higher BS/TV values than the control and BCP/HA groups at both 4 and 12 weeks. No statistically significant difference in newly formed bone was found among the 3 groups at 4 weeks. The BCP group showed significantly higher new bone formation than the BCP/HA group at 12 weeks. CONCLUSIONS: Hard-type crosslinked HA did not show a positive effect on new bone formation and space maintenance. The negative effect of hard-type crosslinked HA may be due to the physical properties of HA that impede osteogenic potential.

The effect of 3-D printed polylactic acid scaffold with and without hyaluronic acid on bone regeneration.

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.

The impact of surface treatment in 3-dimensional printed implants for early osseointegration: a comparison study of three different surfaces.

3D printing technology has been gradually applied to various areas. In the present study, 3D-printed implants were fabricated with direct metal laser sintering technique for a dental single root with titanium. The 3D implants were allocated into following groups: not treated (3D-None), sandblasted with a large grit and acid-etched (3D-SLA), and target-ion-induced plasma-sputtered surface (3D-TIPS). Two holes were drilled in each tibia of rabbit, and the three groups of implants were randomly placed with a mallet. Rabbits were sacrificed at two, four, and twelve weeks after the surgery. Histologic and histomorphometric analyses were performed for the evaluation of mineralized bone-to-implant contact (mBIC), osteoid-to-implant contact (OIC), total bone-to-implant contact (tBIC), mineralized bone area fraction occupancy (mBAFO), osteoid area fraction occupancy (OAFO), and total bone area fraction occupancy (tBAFO) in the inner and outer areas of lattice structure. At two weeks, 3D-TIPS showed significantly higher inner and outer tBIC and inner tBAFO compared with other groups. At four weeks, 3D-TIPS showed significantly higher outer OIC than 3D-SLA, but there were no significant differences in other variables. At twelve weeks, there were no significant differences. The surface treatment with TIPS in 3D-printed implants could enhance the osseointegration process in the rabbit tibia model, meaning that earlier osseointegration could be achieved.

Retrospective study of alveolar ridge preservation compared with no alveolar ridge preservation in periodontally compromised extraction sockets.

BACKGROUND: To minimize alveolar bone resorption, alveolar ridge preservation (ARP) has been proposed. Recently, interest in improving the feasibility of implant placement has gradually increased, especially in situations of infection such as periodontal and/or endodontic lesions. The aim of this study was to investigate if ARP improves feasibility of implant placement compared with no ARP in periodontally compromised sites. Secondary endpoints were the necessity of bone graft at the time of implant placement and implant failure before loading at ARP compared with no ARP. MATERIAL AND METHODS: This retrospective study was performed using dental records and radiographs obtained from patients who underwent tooth extraction due to chronic periodontal pathology. Outcomes including the feasibility of implant placement, horizontal bone augmentation, vertical bone augmentation, sinus floor elevation, total bone augmentation at the time of implant placement, and implant failure before loading were investigated. Multivariable logistic regression analysis was performed to examine the influence of multiple variables on the clinical outcomes. RESULTS: In total, 418 extraction sites (171 without ARP and 247 with ARP) in 287 patients were included in this study. The ARP group (0.8%) shows significantly lower implant placement infeasibility than the no ARP group (4.7%). Horizontal and vertical bone augmentations were significantly influenced by location and no ARP. Total bone augmentation was significantly influenced by sex, location, and no ARP. CONCLUSION: ARP in periodontally compromised sites may improve the feasibility of implant placement. In addition, ARP attenuate the severity of the bone augmentation procedure.

Periodontal Regeneration Using Recombinant Human Bone Morphogenetic Protein-2 and a Bilayer Collagen Matrix.

Previous studies demonstrated that recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered using a collagen sponge could be a candidate for periodontal regeneration therapy. However, there is little evidence related to rhBMP-2 delivered with a bilayer collagen matrix. The aim of this study was to investigate the proper dose of rhBMP-2 using a bilayer collagen matrix for periodontal regeneration in a 1-wall defect. The mandibular first premolars and first molars of 6 beagle dogs were extracted, and an 8-week healing period was allowed. One-wall intrabony defects (4 mm in width and 5 mm in height) were made on the mesial side of the 2nd premolar and/or the distal side of the 4th premolar bilaterally. Subsequently, a bilayer collagen matrix containing 0 µg (C), 200 µg (T1), or 500 µg (T2) of lyophilized rhBMP-2 was randomly applied to the defect area. Calcein and xylenol orange were injected at 4 and 8 weeks following the surgery, respectively, to label periodic bone formation. After a 12-week healing period, the animals were sacrificed for micro-computed tomography and histomorphometric analysis. Bone mineral density and bone volume density showed statistically significant differences between the control group and group T1, while no significant differences were observed between the control group and group T2 or between groups T1 and T2. The bone height in groups T1 and T2 was smaller than that in the control group. Low doses of rhBMP-2 delivered using a bilayer collagen matrix in 1-wall intrabony defects can promote periodontal regeneration compared to no or high doses of rhBMP-2.