Vertical bone augmentation using collagenated or non-collagenated bone substitute materials with or without recombinant human bone morphogenetic protein-2 in a rabbit calvarial model

Purpose The aim of this study was to determine 1) the bone-regenerative effect of porcine bone block materials with or without collagen matrix incorporation, 2) the effect of a collagen barrier, and 3) the effect of adding recombinant human bone morphogenetic protein-2 (rhBMP-2) to the experimental groups. Methods Four treatment modalities were applied to rabbit calvaria: 1) deproteinized bovine bone mineral blocks (DBBM), 2) porcine bone blocks with collagen matrix incorporation (PBC), 3) porcine bone blocks alone without collagen matrix incorporation (PB), and 4) PBC blocks covered by a collagen membrane (PBC+M). The experiments were repeated with the addition of rhBMP-2. The animals were sacrificed after either 2 or 12 weeks of healing. Micro-computed tomography (micro-CT), histologic, and histomorphometric analyses were performed. Results Micro-CT indicated adequate volume stability in all block materials. Histologically, the addition of rhBMP-2 increased the amount of newly formed bone (NB) in all the blocks. At 2 weeks, minimal differences were noted among the NB of groups with or without rhBMP-2. At 12 weeks, the PBC+M group with rhBMP-2 presented the greatest NB (P0.05 without rhBMP-2, P<0.05 with rhBMP-2). Conclusions The addition of rhBMP-2 enhanced NB formation in vertical augmentation using bone blocks, and a collagen barrier may augment the effect of rhBMP-2

Immediate implant placement in conjunction with guided bone regeneration and/or connective tissue grafts: an experimental study in canines

PURPOSE This study was conducted to assess the effect of hard and/or soft tissue grafting on immediate implants in a preclinical model. METHODS In 5 mongrel dogs, the distal roots of P2 and P3 were extracted from the maxilla (4 sites in each animal), and immediate implant placement was performed. Each site was randomly assigned to 1 of the following 4 groups: i) gap filling with guided bone regeneration (the GBR group), ii) subepithelial connective tissue grafting (the SCTG group), iii) GBR and SCTG (the GBR/SCTG group), and iv) no further treatment (control). Non-submerged healing was provided for 4 months. Histological and histomorphometric analyses were performed. RESULTS Peri-implant tissue height and thickness favored the SCTG group (height of peri-implant mucosa: 1.14 mm; tissue thickness at the implant shoulder and ±1 mm from the shoulder: 1.14 mm, 0.78 mm, and 1.57 mm, respectively; median value) over the other groups. Bone grafting was not effective at the level of the implant shoulder and on the coronal level of the shoulder. In addition, simultaneous soft and hard tissue augmentation (the GBR/SCTG group) led to a less favorable tissue contour compared to GBR or SCTG alone (height of peri-implant mucosa: 3.06 mm; thickness of peri-implant mucosa at the implant shoulder and ±1 mm from the shoulder: 0.72 mm, 0.3 mm, and 1.09 mm, respectively). CONCLUSION SCTG tended to have positive effects on the thickness and height of the peri-implant mucosa in immediate implant placement. However, simultaneous soft and hard tissue augmentation might not allow a satisfactory tissue contour in cases where the relationship between implant position and neighboring bone housing is unfavorable

Augmentation of keratinized tissue at tooth and implant sites by using autogenous grafts and collagen-based soft-tissue substitutes

AIM To investigate the effect of three treatment modalities on the gain of keratinized tissue (KT) at tooth and implant sites in dogs. MATERIALS AND METHODS In five dogs, the distal roots of the mandibular second, third and fourth premolars were extracted, while the mesial roots were maintained. After 2 months of healing, implants were placed with KT excision. After another 2 months of healing, free gingival grafts, collagen-based matrices and apically positioned flap only were applied. The height of KT was measured during implant placement, immediately before soft-tissue grafting and after 10, 30 and 60 days. RESULTS Two months after KT excision, spontaneous KT regrowth was greater at tooth sites than at implant sites (median, 2.0 mm vs. 1.1 mm). The outcomes of soft-tissue grafting at implant sites favoured the free gingival graft treatment, with a greater final median height (5.0-5.5 mm) and increase in KT (4.0-4.2 mm). Locations of the recipient sites significantly influenced KT regeneration at both tooth and implant sites. CONCLUSIONS At implant sites, the free gingival graft treatment led to higher KT regeneration. At tooth sites, however, the differences between the three treatment modalities seemed clinically irrelevant

Recombinant bone morphogenetic protein-2 and platelet-derived growth factor-BB for localized bone regeneration. Histologic and radiographic outcomes of a rabbit study

OBJECTIVES: Improvement in localized bone regeneration is needed to avoid the use of autogenous tissue. For that purpose, the use biologic mediators was proposed. The aim was to test whether or not one of two biologic mediators, recombinant human bone morphogenetic protein-2 (rhBMP-2) or recombinant platelet-derived growth factor (rhPDGF-BB), is superior to the other and to control groups for localized bone regeneration. MATERIALS AND METHODS: Four cylinders (height: 5 mm; diameter: 7 mm) were screwed on the parietal and frontal bones at the cranium in 12 rabbits. The cylinders either received (i) deproteinized bovine bone mineral (DBBM) mixed rhBMP-2 (DBBM/BMP-2), (ii) DBBM mixed with rhPDGF-BB (DBBM/PDGF), (iii) DBBM (DBBM), and (iv) empty control (control). Rabbits were euthanized at 2 and 8 weeks (n = 6, respectively). Conventional histomorphometric and micro-CT analyses were performed. Parametric linear mixed models were applied for the analyses with Bonferroni correction for the multiple group comparisons. RESULTS: The area of bone regeneration (histology; AAHisto ) at 2 weeks peaked for DBBM (41.91%) with statistically significantly greater values compared to DBBM/PDGF and the control group (P < 0.05). At 8 weeks, mean AAHisto values were 96.29% (DBBM/BMP-2), 46.37% (DBBM/PDFG), 39.66% (DBBM), and 35.98% (control) (DBBM/BMP-2 vs. all groups (P < 0.05)). At 8 weeks, bone regeneration was greatest for DBBM/BMP-2 (35.62%) with statistically significant differences compared to all other groups (P < 0.05). The area of bone regeneration (micro-CT; AAm-CT ) at 2 weeks amounted to 43.87% (DBBM/BMP-2), 42.81% (DBBM/PDFG), 48.71% (DBBM), and 0.96% (control). The control group demonstrated statistically significantly less AAm-CT compared to all groups (P < 0.05). At 8 weeks, mean AAm-CT values were 63.65% (DBBM/BMP-2), 50.21% (DBBM/PDFG), 44.81% (DBBM), and 4.57% (control) (P > 0.05). CONCLUSIONS: The use of rhBMP-2 significantly enhanced bone regeneration compared to all other groups including the group with rhPDGF-BB

Prediction of strawberry fruit yield based on cultivar-specific growth models in the tunnel-type greenhouse

The strawberry growth and fruit yield of five Korean cultivars in the tunnel-type greenhouse predicted using their growth. The number of leaves, petiole length, leaf length and width, crown diameter, and the ratio of red and far-red (RFR) of the five Korean cultivars were measured during the cultivation period. The number of leaves of all cultivars exhibited a similar trend during this period; the plant and petiole length of ‘Maehyang’ were the longest, leaf length exhibited similar trends in all five cultivars except for ‘Jukhyang’, the leaf width of ‘Arihyang’, was the longest, and crown diameter of ‘Keumsil’ was the thickest. The leaf length, crown diameter, and RFR were associated with the fruit yield in the multiple linear regression. When a single model was used to predict the yield of all five cultivars, the correlation between expected yield and actual yield was r = 0.53. When cultivar-specific models were built for the prediction, the correlation increased to r = 0.77. The results indicated that the fruit yield of strawberry cultivars could be better predicted by considering cultivar-specific information, so it may be necessary to consider individual cultivars specifically rather than all cultivars simultaneously

Treatment concepts for the posterior maxilla and mandible: short implants versus long implants in augmented bone

The aim of this narrative review is to describe treatment options for the posterior regions of the mandible and the maxilla, comparing short implants vs. longer implants in an augmented bone. The dental literature was screened for treatment options enabling the placement of dental implants in posterior sites with a reduced vertical bone height in the maxilla and the mandible. Short dental implants have been increasingly used recently, providing a number of advantages including reduced patient morbidity, shorter treatment time, and lower costs. In the posterior maxilla, sinus elevation procedures were for long considered to be the gold standard using various bone substitute materials and rendering high implant survival rates. More recently, implants were even placed without any further use of bone substitute materials, but the long-term outcomes have yet to be documented. Vertical bone augmentation procedures in the mandible require a relatively high level of surgical skill and allow the placement of standard-length dental implants by the use of autogenous bone blocks. Both treatment options, short dental implants, and standard-length implants in combination with vertical bone augmentation procedures, appear to result in predictable outcomes in terms of implant survival rates. According to recent clinical studies comparing the therapeutic options of short implants vs. long implants in augmented bone, the use of short dental implants leads to a number of advantages for the patients and the clinician

Volume stability of the augmented sinus using a collagenated bovine bone mineral grafted in case of a perforated Schneiderian membrane: An experimental study in rabbits

Objectives: To determine the volume stability of a sinus augmented with a collagenated bovine bone mineral (CBBM) in case of an intact or perforated Schneiderian membrane (SM). Materials and methods: A bilateral sinus augmentation procedure was performed in eight rabbits. The SM was intentionally perforated in one side (SMP group), while it remained intact in contra-lateral side (control group) and the same amount of CBBM was then grafted. At 12 weeks, the animals were euthanized for radiographic and histomorphometric analyses. Results: The augmented volume did not differ significantly between the two groups: 262.2 ± 32.1 mm3 in SMP group and 261.9 ± 48.5 mm3 in the control group (p = .959). There was no significant difference in the total augmented area: 24.7 ± 5.2 mm2 in SMP group and 23.2 ± 2.9 mm2 in the control group (p = .773). The areas of newly formed bone also did not differ significantly between the two groups, but was significantly lower at the centre of the augmented region than in the region of the surgical window in both groups (p < .05). Conclusion: A perforation of the SM in a rabbit model does neither impact the augmented volume nor new bone formation following grafting of the sinus with a CBBM. Keywords: Schneiderian membrane; animal study; volume stability; xenograft. © 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

Tissue integration of zirconia and titanium implants with and without buccal dehiscence defects-A histologic and radiographic preclinical study

OBJECTIVE To histologically and radiographically evaluate soft (primary outcome) and hard tissue integration of two-piece titanium and zirconia dental implants with/without buccal dehiscence defects. MATERIALS & METHODS In six dogs, five implants were randomly placed on both sides of the mandible: (a) Z1: a zirconia implant (modified surface) within the bony housing, (b) Z2: a zirconia implant (standard surface) within the bony housing, (c) T: a titanium implant within the bony housing, (d) Z1_D: a Z1 implant placed with a buccal bone dehiscence (3 mm in height, identical width to implant body), and (e) T_D: a titanium implant placed with a buccal bone dehiscence. Two weeks of healing and 6 months of loading were applied on each hemi-mandible, respectively. RESULTS The median level of the margo mucosae shifted more apically over time in all groups (borderline statistical significance in groups Z1_D: -0.52 mm and T_D: -1.26 mm). The median height of the peri-implant mucosa in groups Z1_D and T_D was greatest at 2 weeks and 6 months, but the linear change in the peri-implant mucosa was statistically significant only for group T_D over time (-1.45 mm). Z1 demonstrated a higher bone-to-implant contact compared to Z2 and T. Minimal change of radiographic marginal bone levels in all groups was observed (<1 mm). CONCLUSION When buccal dehiscence was presented, titanium implants presented significant loss of peri-implant mucosal height compared to zirconia implants with a modified surface, due to greater apical shift of the margo mucosae. A modified zirconia surface enhanced osseointegration

Core Ossification of Bone Morphogenetic Protein-2-Loaded Collagenated Bone Mineral in the Sinus

The objective of this study was to investigate in vitro release kinetics and ossification patterns of bone morphogenetic protein-2-soaked collagenated porcine bone mineral (BMP-2/CPBM) in rabbit sinuses. Release kinetics of BMP-2/CPBM was determined in vitro up to 56 days. In 16 rabbits, BMP-2/CPBM (BMP group) and CPBM alone (control group) were bilaterally grafted in both sinuses. After 4 (N = 8) and 12 (N = 8) weeks, radiographic and histologic analyses were performed. Approximately 40% of BMP-2 was released from CPBM during 3 days in vitro; release maintained at a reduced level until day 56. In vivo, new bone formation in BMP group was dominant at the center and decreased toward the borders of the sinus, while it mainly possessed close to the sinus membrane and basal bone in control group. At the center, significantly more new bone was found in BMP group compared to control group at 4 weeks (29.14% vs. 16.50%; p < 0.05). The total augmented volume of BMP group was significantly greater than control group at 4 (370.13 mm$^{3}$ vs. 299.32 mm$^{3}$) and 12 (400.40 mm$^{3}$ vs. 290.10 mm$^{3}$) weeks (p < 0.05). In conclusion, BMP-2/CPBM demonstrated a core ossification with a greater augmented volume and new bone formation in the center of the sinus compared to CPBM alone. Impact statement The center of the augmented maxillary sinus tends to show a slower and inferior new bone formation compared to the sites near the sinus membrane and basal bone. In this study, bone morphogenetic protein-2 (BMP-2) loaded onto collagenated porcine bone mineral (CPBM) resulted in a greater augmented volume and new bone formation at the center of the grafted sinus compared to CPBM alone. Therefore, BMP-2-added CPBM in maxillary sinus augmentation may potentially be beneficial to the clinicians, in terms of accelerating the new bone formation at the center area where the apical half of the implant fixture usually places