Diverse patterns of bone regeneration in rabbit calvarial defects depending on the type of collagen membrane.

PURPOSE: Various crosslinking methods have been introduced to increase the longevity of collagen membranes. The aim of this study was to compare and evaluate the degradation and bone regeneration patterns of 3 collagen membranes. METHODS: Four 8-mm-diameter circular bone defects were created in the calvaria of 10 rabbits. In each rabbit, each defect was randomly allocated to 1) the sham control group, 2) the non-crosslinked collagen sponge (NS) group, 3) the chemically crosslinked collagen membrane (CCM) group, or 4) the biphasic calcium phosphate (BCP)-supplemented ultraviolet (UV)-crosslinked collagen membrane (UVM) group. Each defect was covered with the allocated membrane without any graft material. Rabbits were sacrificed at either 2 or 8 weeks post-surgery, and radiographic and histologic analyses were done. RESULTS: New bone formed underneath the membrane in defects in the CCM and UVM groups, with a distinctive new bone formation pattern, while new bone formed from the base of the defect in the NS and control groups. The CCM maintained its shape until 8 weeks, while the UVM and NS were fully degraded at 8 weeks; simultaneously, sustained inflammatory infiltration was found in the margin of the CCM, while it was absent in the UVM. In conclusion, the CCM showed longer longevity than the UVM, but was accompanied by higher levels of inflammation. CONCLUSIONS: Both the CCM and UVM showed distinctive patterns of enhancement in new bone formation in the early phase. UV crosslinking can be a biocompatible alternative to chemical crosslinking.

Oral Fluid Biomarkers for Diagnosing Gingivitis in Human: A Cross-Sectional Study.

Diagnoses based on oral fluid biomarkers have been introduced to overcome limitations of periodontal probe-based diagnoses. Diagnostic ability of certain biomarkers for periodontitis have been identified and widely studied, however, such studies targeting gingivitis is scarce. The aims of this study were to determine and compare the efficacies and accuracies of eight biomarkers in diagnosing gingivitis with the aid of receiver operating characteristic (ROC) curves. The probing depth (PD), clinical attachment loss (CAL), bleeding on probing (BOP), gingival index (GI), and plaque index (PI) were examined in 100 participants. Gingival crevicular fluid was collected using paper points, and whole-saliva samples were collected using cotton roll. Samples were analyzed using enzyme-linked immunosorbent assay kits for the different biomarkers. The levels of matrix metalloproteinase (MMP)-8, MMP-9, lactoferrin, cystatin C, myeloperoxidase (MPO), platelet-activating factor, cathepsin B, and pyridinoline cross-linked carboxyterminal telopeptide of type I collagen were analyzed. MPO and MMP-8 levels in saliva were strongly correlated with gingivitis, with Pearson's correlation coefficients of 0.399 and 0.217, respectively. The area under the curve (AUC) was largest for MMP-8, at 0.814, followed by values of 0.793 and 0.777 for MPO and MMP-9, respectively. The clinical parameters of GI and PI showed strong correlations and large AUC values, whereas PD and CAL did not. MMP-8 and MPO were found to be effective for diagnosing gingivitis. Further investigations based on the results of this study may identify clinically useful biomarkers for the accurate and early detection of gingivitis.

Distinctive bone regeneration of calvarial defects using biphasic calcium phosphate supplemented ultraviolet-crosslinked collagen membrane.

PURPOSE: To overcome several drawbacks of chemically-crosslinked collagen membranes, modification processes such as ultraviolet (UV) crosslinking and the addition of biphasic calcium phosphate (BCP) to collagen membranes have been introduced. This study evaluated the efficacy and biocompatibility of BCP-supplemented UV-crosslinked collagen membrane for guided bone regeneration (GBR) in a rabbit calvarial model. METHODS: Four circular bone defects (diameter, 8 mm) were created in the calvarium of 10 rabbits. Each defect was randomly allocated to one of the following groups: 1) the sham control group (spontaneous healing); 2) the M group (defect coverage with a BCP-supplemented UV-crosslinked collagen membrane and no graft material); 3) the BG (defects filled with BCP particles without membrane coverage); and 4) the BG+M group (defects filled with BCP particles and covered with a BCP-supplemented UV-crosslinked collagen membrane in a conventional GBR procedure). At 2 and 8 weeks, rabbits were sacrificed, and experimental defects were investigated histologically and by micro-computed tomography (micro-CT). RESULTS: In both micro-CT and histometric analyses, the BG and BG+M groups at both 2 and 8 weeks showed significantly higher new bone formation than the control group. On micro-CT, the new bone volume of the BG+M group (48.39±5.47 mm3) was larger than that of the BG group (38.71±2.24 mm3, P=0.032) at 8 weeks. Histologically, greater new bone area was observed in the BG+M group than in the BG or M groups. BCP-supplemented UV-crosslinked collagen membrane did not cause an abnormal cellular reaction and was stable until 8 weeks. CONCLUSIONS: Enhanced new bone formation in GBR can be achieved by simultaneously using bone graft material and a BCP-supplemented UV-crosslinked collagen membrane, which showed high biocompatibility and resistance to degradation, making it a biocompatible alternative to chemically-crosslinked collagen membranes.

Bioactive characteristics of an implant surface coated with a pH buffering agent: an in vitro study.

PURPOSE: The purpose of this study was to evaluate the effectiveness of conventional sandblasted, large-grit, acid-etched (SLA) surface coated with a pH buffering solution based on surface wettability, blood protein adhesion, osteoblast affinity, and platelet adhesion and activation. METHODS: Titanium discs and implants with conventional SLA surface (SA), SLA surface in an aqueous calcium chloride solution (CA), and SLA surface with a pH buffering agent (SOI) were prepared. The wetting velocity was measured by the number of threads wetted by blood over an interval of time. Serum albumin adsorption was tested using the bicinchoninic acid assay and by measuring fluorescence intensity. Osteoblast activity assays (osteoblast adhesion, proliferation, differentiation, mineralization, and migration) were also performed, and platelet adhesion and activation assays were conducted. RESULTS: In both the wetting velocity test and the serum albumin adsorption assay, the SOI surface displayed a significantly higher wetting velocity than the SA surface (P=0.000 and P=0.000, respectively). In the osteoblast adhesion, proliferation, differentiation, and mineralization tests, the mean values for SOI were all higher than those for SA and CA. On the osteoblast migration, platelet adhesion, and activation tests, SOI also showed significantly higher values than SA (P=0.040, P=0.000, and P=0.000, respectively). CONCLUSIONS: SOI exhibited higher hydrophilicity and affinity for proteins, cells, and platelets than SA. Within the limits of this study, it may be concluded that coating an implant with a pH buffering agent can induce the attachment of platelets, proteins, and cells to the implant surface. Further studies should be conducted to directly compare SOI with other conventional surfaces with regard to its safety and effectiveness in clinical settings.

Maxillary sinus augmentation using biphasic calcium phosphate: dimensional stability results after 3-6 years.

PURPOSE: This study was designed to observe the resorption pattern of biphasic calcium phosphate (BCP) used for maxillary sinus augmentation over a 3- to 6-year healing period, and to investigate factors affecting the resorption of BCP. METHODS: A total of 47 implants placed in 27 sinuses of 22 patients were investigated. All patients had residual bone height less than 5 mm at baseline. The modified Caldwell-Luc approach was used to elevate the maxillary sinus membrane, and the sinus cavity was filled with BCP (70% hydroxyapatite and 30% ß-tricalcium phosphate). Implant placement was done simultaneously or in a staged manner. Serial radiographic analysis was performed up to 6 years postoperatively. RESULTS: During the follow-up period, no implant loss was reported. The mean reduced height of the augmented sinus (RHO) was 0.27±1.08 mm at 36 months, and 0.89±1.39 mm at 72 months postoperatively. Large amounts of graft material (P=0.021) and a long healing period (P=0.035) significantly influenced the amount of RHO. In particular, there was a significant relationship between a healing period longer than 40 months and RHO. CONCLUSIONS: BCP can achieve proper dimensional stability with minimal reduction of the graft height in a 3- to 6-year healing period after maxillary sinus augmentation. The healing period and the amount of graft material influenced the resorption of BCP.

Bone regeneration using three-dimensional hexahedron channel structured BCP block in rabbit calvarial defects.

The purpose of this study is to evaluate the efficacy of bone regeneration and volume maintenance of the three-dimensional (3D) structured biphasic calcium phosphate (BCP) block with porous hexahedron channels in a rabbit calvarial model. In this work, four circular defects (diameter: 8 mm) in calvarium of rabbits were randomly assigned to (1) negative control (control), (2) 3D hexahedron channel structured BCP block, (3) deproteinized bovine bone mineral particle, and (4) deproteinized porcine bone mineral particle. Animals were euthanized at 2 (n = 5) and 8 weeks (n = 5). Outcome measures included micro-computed tomography (CT) and histomorphometrical analysis. Results indicated that in micro-CT, BCP group showed the highest new bone volume with significant difference compared to control (p = 0.008) at 8 weeks. Histomorphometrically, total augmented area of BCP group was the highest with significant difference compared to control (p = 0.008) at 8 weeks. BCP group also maintained total volume of the original defect without collapsing. BCP block with 3D hexahedron channel structure seems to have favorable osteogenic and volume maintaining ability and highly porous structure might attribute to new bone formation. Further studies regarding the optimal internal structure and porosity of the BCP block bone substitute are needed. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2254-2262, 2019.

3D-printed polycaprolactone scaffold mixed with ß-tricalcium phosphate as a bone regenerative material in rabbit calvarial defects.

Defect-specific bone regeneration using 3-dimensional (3D) printing of block bone has been developed. Polycaprolactone (PCL) is biocompatible polymer that can be used as 3D scaffold. The aim of this study is to assess the biocompatibility and osteogenic efficacy of 3D printed PCL scaffold and to evaluate the effectiveness of ß-tricalcium phosphate (ß-TCP) addition in PCL scaffold. In this work, four circular defects (diameter: 8 mm) in rabbit calvarium were randomly assigned to (1) negative control (control), (2) PCL block (PCL), (3) PCL mixed with 10 wt% ß-TCP (PCL/ß-TCP), and (4) PCL/ß-TCP plus collagen membrane (PCL/ß-TCP + M). Animals were euthanized at 2 (n = 5) and 8 weeks (n = 5). Results indicated that in micro-CT, PCL/ß-TCP + M showed the highest total augmented volume and new bone volume at 8 weeks, but there was no significant difference among four groups. Histomorphometrically, PCL, PCL/ß-TCP, and PCL/ß-TCP + M showed the significantly higher total augmented area compared to the control. PCL/ß-TCP + M showed the highest new bone area but not statistically higher than the control. New bone formation deep inside the scaffold was observed only in ß-TCP added scaffold. PCL showed high biocompatibility with great volume maintenance. Addition of ß-TCP to PCL seemed to increase hydrophilicity and osteoconductivity. Developments in 3D-printed PCL material are expected. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1254-1263, 2019.