Dimensional changes of the maxillary sinus augmented with a collagenated synthetic bone block or synthetic bone particulates: A pre-clinical study in rabbits

Enhancing guided bone regeneration with cross-linked collagen-conjugated xenogeneic bone blocks and membrane fixation: A preclinical in vivo study

OBJECTIVE

To determine whether combining cross-linked (CL) collagen-integrated xenogeneic bone blocks stabilized with the fixation of resorbable collagen membranes (CM) can enhance guided bone regeneration (GBR) in the overaugmented calvarial defect model.

MATERIALS AND METHODS

Four circular defects with a diameter of 8 mm were prepared in the calvarium of 13 rabbits. Defects were randomly assigned to receive one of the following treatments: (i) non-cross-linked (NCL) porcine-derived collagen-embedded bone block covered by a CM without fixation (NCL + unfix group); (ii) NCL bone block covered by CM with fixation using bone-tack (NCL + fix group); (iii) cross-linked (CL) porcine-derived collagen-embedded bone block covered by CM without fixation (CL + unfix group); and (iv) CL bone block covered by CM with fixation using bone-tack fixation (CL + fix group). The efficacy of GBR was assessed through histological and molecular analyses after 2 and 8 weeks.

RESULTS

At 2 weeks, there were no significant differences in histologically measured areas of newly formed bone among the groups. At 8 weeks, however, the CL + fix group exhibited a larger area of new bone (5.08 ± 1.09 mm2, mean ± standard deviation) compared to the NCL + unfix (1.62 ± 0.42 mm2; p < .0083), NCL + fix (3.97 ± 1.39 mm2) and CL + unfix (2.55 ± 1.04 mm2) groups. Additionally, the expression levels of tumour necrosis factor-alpha, fibroblast growth factor-2, vascular endothelial growth factor, osteocalcin and calcitonin receptor were significantly higher in the CL + fix group compared to the other three groups (p < .0083).

CONCLUSION

Cross-linked bone blocks stabilized with collagen membrane fixation can significantly enhance GBR.

The adjunctive effect of polydeoxyribonucleotide on bone formation in alveolar ridge preservation: A pre-clinical in vivo study

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.

Ridge preservation using a self-retaining block type bone substitute for extraction sockets with buccal dehiscence defects - A preclinical study

OBJECTIVE

To evaluate the effect of a self-retaining block-type bone substitute (srBB) on the dimensional stability of the horizontal ridge width at the coronal level in a buccal dehiscence model.

MATERIALS AND METHODS

Four box-shaped bone defects with a buccal dehiscence were surgically prepared in the partially edentulous mandible (n = 6). Experimental biomaterials were randomly assigned to each site: (1) Control group: no treatment, (2) particle-type bone substitute (PBS) group, (3) collagenated soft block bone substitute (csBB) group, and (4) self-retaining synthetic block bone (srBB) group. In all grafted groups, a collagen membrane covered the biomaterials. At 16 weeks, clinical, histological, and radiographic analyses were performed.

RESULTS

Three of the six blocks in the srBB group became exposed and fell out during the first week after surgery. Therefore, the remaining three specimens were renamed RsrBB group. The RsrBB group showed an increase horizontal ridge compared to the pristine bone width at 2-4 mm below the CEJ, while the other groups showed resorption (augmented width at 2 mm below: 4.2, 42.4, 36.2, and 110.1% in the control, PBS, csBB, and RsrBB groups, respectively). The mineralized bone area was largest in the RsrBB group (4.74, 3.44, 5.67, and 7.77 mm2 in the control, PBS, csBB, and RsrBB groups, respectively.).

CONCLUSIONS

The srBB group demonstrated the highest volume stability at the coronal level. These findings would potentially suggest that self-retaining block bone substitute might be a good candidate for alveolar ridge preservation.

A critical look at outcome measures: Comparison between four dental research journals by use of a hierarchical model

AIM

To assess the status quo of outcome measures used in treatment studies in Endodontics, and potentially identify strategies for improvement, by (i) systematically assessing the outcome measures using a conceptual model and (ii) comparing these with measures used in corresponding studies in the adjacent fields.

METHODOLOGY

The International Endodontic Journal, Caries Research, The Journal of Clinical Periodontology and The Journal of Oral & Facial Pain and Headache were selected to cover four adjacent dental disciplines. In each journal, the 50 most recent consecutive publications fulfilling inclusion criteria were included. A hierarchical model for diagnostic imaging studies was modified to assess studies related to treatment. The model comprised six levels, with technical as the lowest level and societal as the highest. Extracted data included study origin, study type, and identified outcome measures. Fisher's Exact Tests with Bonferroni corrections compared studies. p < .05 was considered statistically significant.

RESULTS

Amongst 756 publications, the 200 most recent studies matching the inclusion criteria were identified. Less than half (36.5%) assessed the clinical, patient, or societal aspects of treatment; 10.0% in International Endodontic Journal, 28.0% in Caries Research, 38.0% in Journal of Clinical Periodontology, and 70.0% in Journal of Oral & Facial Pain and Headache (p < .001).

CONCLUSIONS

According to included publications, research on treatment within the endodontic field is mainly focusing on technical and biological outcomes. The benefits of patients and society were less frequently examined than in corresponding journals in adjacent disciplines. When designing studies, including higher-level outcomes should be considered.

Effect of polydeoxyribonucleotide on early bone formation in lateral bone augmentation with immediate implant placement: an experimental in vivo study

This study investigated early bone formation using collagenated biphasic calcium phosphate (CBCP) with or without polynucleotide (PDRN). Third (P3) or fourth (P4) premolars of six male beagle dogs were extracted and 5-mm-high dehiscence defects were created, followed by 3D-printed implant placement. The buccal bone defects were grafted with (i) CBCP and collagen membrane or (ii) CBCP soaked in polydeoxyribonucleotide (CBCP/PDRN) and collagen membrane. Samples of the experimental sites were harvested at 2- and 6-weeks post-surgery. The specimens were evaluated with radiologic and histomorphometric analysis. No significant differences were found between the CBCP and CBCP/PDRN groups in the micro-CT analysis at 2 or 6 weeks. No significant differences were observed in bone-to-implant contact (BIC) or bone area fraction occupancy (BAFO) in buccal augmented and lingual non-augmented areas. In the qualitative analysis, the new bone (NB) area and NB proportion in buccal augmented areas showed significantly higher values in the CBCP/PDRN group than in the CBCP group at 2 and 6 weeks. Peri-implant buccal dehiscence defects with immediate 3D-printed implant placement were corrected using a collagen membrane and CBCP or CBCP/PDRN. PDRN might have the potential to facilitate early bone formation with sufficient stability over time in dehiscence defects.

Comparison of osteogenesis and osseointegration following implant placement with simultaneous maxillary sinus augmentation using particulate and collagenated block types of deproteinized porcine bone mineral: a radiographic and histomorphometric analysis

OBJECTIVES

This study aimed to compare osseointegration and osteogenesis after single-stage maxillary sinus augmentation with the lateral window using particulate deproteinized porcine bone mineral (PDPBM) and collagenated block deproteinized porcine bone mineral (BDPBM).

MATERIALS AND METHODS

Bi-maxillary premolars of six beagle dogs were extracted. Eight weeks later, an implant was placed into each augmented sinus with PDPBM or BDPBM according to a split-mouth design. Eight weeks later, all specimens were harvested. Each specimen was separated into the region of interest with the implant (ROI-I) and region of interest with sinus augmented area (ROI-S) 5 mm away from ROI-I. ROI-I and ROI-S were evaluated through micro-computed tomography and histomorphometry.

RESULTS

Bone substitute insertion took longer for the PDPBM group than for the BDPBM group (P = 0.002). In ROI-I, three-dimensional bone-to-implant contact (BIC) did not show statistically significant differences between the groups. Two-dimensional BIC also showed comparable values for both groups. In ROI-S, the graft material volume/tissue volume, trabecular bone pattern factor, and structural model index were higher in the BDPBM group than in the PDPBM group (P < 0.05). The proportions of new bone, graft material, and connective tissue were not significantly statistically different between groups. Less new bone was found in the apical area than in the coronal or middle areas in the BCPBM group (P < 0.05).

CONCLUSIONS

BDPBM may save time in inserting bone substitutes and provide comparable osteogenesis and osseointegration to PDPBM.

CLINICAL RELEVANCE

When performing sinus augmentation, BDPBM might improve operator's convenience with comparable biological results compared to PDPBM.

Early tissue and healing responses after maxillary sinus augmentation using horizontal platelet rich fibrin bone blocks

BACKGROUND

The effects of horizontal platelet-rich fibrin (H-PRF) bone block on the healing and immune response during sinus augmentation have not been fully investigated histologically at early time points.

METHODS

Eighteenth male New Zealand white rabbits underwent bilateral sinus augmentation and were divided into two groups: deproteinized bovine bone mineral (DBBM) alone and H-PRF + DBBM (H-PRF bone block) group. Maxilla samples were collected at 3, 7 and 14 days post sinus augmentation procedures and analyzed using histological staining for the number of inflammatory cells, new blood vessels and evidence for early osteoclast bone turnover/remodeling. Furthermore, the effects of H-PRF bone blocks on the migration of osteoblasts and THP-1 macrophages were evaluated using a Transwell assay in vitro.

RESULTS

A higher number of immune cells were found in the H-PRF bone block group at 3 and 7 days post-surgery when compared to the DBBM alone group,most notably in the regions close to the mucosal lining and bone plates. Furthermore, a significantly greater number of new blood vessel formations and early signs of osteoclast development were found in the H-PRF bone block group at 14 days. The in vitro transwell assay further confirmed that culture medium from H-PRF bone block markedly promote the migration of osteoblasts and THP-1 macrophages.

CONCLUSIONS

The findings from this study have shown that H-PRF bone block is capable of increasing early immune cell infiltration leading to the acceleration of neovascularization and speeding the process of bone metabolism in vivo following maxillary sinus grafting with DBBM.

Comparative analysis of two biomaterials mixed with autogenous bone graft for vertical ridge augmentation: A histomorphometric study in humans

BACKGROUND

The vertical increase of the alveolar ridge dimension using allograft or xenograft mixed with autogenous bone graft and covered by a nonabsorbable high-density polytetrafluoroethylene (d-PTFE) membrane is well documented in the literature.

PURPOSE

The aim of this study was to assess vital mineralized tissue formation in vertical ridge augmentation (VRA) procedures using autogenous bone chips mixed either with an allograft or a xenograft.

METHODS

This prospective clinical trial recruited 16 partially edentulous patients to undergo vertical ridge augmentation in one or more sites, making up a total of 24 samples for histological evaluation. Patients were sequentially stratified into Group A (treated with a freeze-dried bone allograft [FDBA] mixed with autogenous bone) or to Group B (treated with a bovine xenograft mixed with autogenous bone). Histological samples were analyzed according to the biomaterial used for VRA. Histological samples were obtained on the same day of membrane removal and implant placement.

RESULTS

Thirty-three implants were placed in 16 sites of regenerated bone via VRA, 13 patients with ridge augmentation in the posterior mandible, and 3 patients with VRA in the anterior maxilla. Group A (FDBA + autogenous) and Group B (xenograft + autogenous) showed a percent vital mineralized tissue (VMT) area of 67.64 ± 16.84 and 60.93 ± 18.25, respectively. A significant difference between the two biomaterials was not observed.

CONCLUSION

When mixed with autogenous bone, either allografts or xenografts may provide a successful augmentation. Either mixture could serve as reliable alternative in VRA for obtaining a high percentage of VMT.

Effect of Schneiderian membrane integrity on bone formation in sinus augmentation: An experimental study in rabbits

AIM

To assess the effect of Schneiderian membrane (SM) perforation on bone formation by applying a particulate deproteinized bovine bone mineral (PBBM).

MATERIALS AND METHODS

Bilateral sinus augmentation was performed in eight rabbits. The same amount of PBBM was placed at a sinus where the SM was intentionally perforated for the perforation group (standardized to 3 mm diameter) and the other sinus with an intact SM that served as the intact group. At 12 weeks, all animals were euthanized for radiographic and histomorphometric analyses.

RESULTS

The area of the newly formed bone in the perforation group was significantly less than that in the intact group (18.7% and 25.5%, respectively, p = .028). The newly formed bone in the area close to the perforated SM was significantly less than that in the intact group (18.7% and 26.1%, respectively, p < .05). However, there was no significant difference in the total augmented area (p = .234) and the total augmented volume (p = .382) between the two groups.

CONCLUSION

SM perforation had an adverse effect on new bone formation, predominantly close to the area of membrane perforation. However, no significant difference was found in the total augmented volume between the SM perforation and the intact groups.

Addition of autogenous bone chips to deproteinized bovine bone mineral does not have additional benefit in lateral ridge augmentation-A preclinical in vivo experimental study

OBJECTIVE

To compare the outcome after extensive lateral guided bone regeneration using deproteinized bovine bone mineral (DBBM) with or without autogenous bone chips in a canine model of chronic horizontal alveolar ridge defect.

MATERIALS AND METHODS

The second, third and fourth lower premolars of both sides were extracted, and the buccal bone walls were completely removed in five beagle dogs. After 4 weeks, DBBM particles mixed with autogenous bone chips at a ratio of 1:1 were grafted at one side (DBBM/Auto group), while DBBM particles alone were grafted at the contralateral side (DBBM group). The graft materials on both sides were covered by a resorbable collagen membrane and fixation pins. Microcomputed tomographic volume and histomorphometric analyses were performed at 16 weeks post-surgery.

RESULTS

The ridges of both groups were recovered horizontally, but new bone formation beyond the original ridge contour at the defect site was not found. The DBBM group exhibited a larger total radiographic augmented volume and new bone volume compared with the DBBM/Auto group, but the differences were minimal (p > .05). Histologically, the regenerated area and new bone area were also slightly larger without any statistical significance in the DBBM group than in the DBBM/Auto group (p > .05).

CONCLUSION

The addition of autogenous bone chips to DBBM for lateral ridge augmentation may confer no advantage over grafting DBBM alone with respect to both space maintenance and de novo bone formation in dogs.

Stiffness Regulates the Morphology, Adhesion, Proliferation, and Osteogenic Differentiation of Maxillary Schneiderian Sinus Membrane-Derived Stem Cells

Recent studies, which aim to optimize maxillary sinus augmentation, have paid significant attention exploring osteogenic potential of maxillary Schneiderian sinus membrane-derived cells (MSSM-derived cells). However, it remains unclear that how MSSM-derived cells could respond to niche's biomechanical properties. Herein, this study investigated the possible effects of substrate stiffness on rMSSM-derived stem cell fate. Initially, rMSSM-derived stem cells with multiple differentiation potential were successfully obtained. We then fabricated polyacrylamide substrates with varied stiffness ranging from 13 to 68 kPa to modulate the mechanical environment of rMSSM-derived stem cells. A larger cell spreading area and increased proliferation of rMSSM-derived stem cells were found on the stiffer substrates. Similarly, cells became more adhesive as their stiffness increased. Furthermore, the higher stiffness facilitated osteogenic differentiation of rMSSM-derived stem cells. Overall, our results indicated that increase in stiffness could mediate behaviors of rMSSM-derived stem cells, which may serve as a guide in future research to design novel biomaterials for maxillary sinus augmentation.