International Journal of Periodontics & Restorative Dentistry, Supplement/2016

This study aimed to assess the efficacy of biphasic calcium phosphate (BCP) with adjunct recombinant human bone morphogenetic protein-2 (rhBMP-2), with and without collagen membrane (CM), in regeneration of standardized rat calvarial defects. Thirty female Wistar albino rats with a mean age of 12 weeks and mean weight of 300 g were used. The skin over the calvaria was exposed using a full-thickness flap. A standardized defect measuring 4.6 mm in diameter was created in the parietal bone. The defects were randomly divided into the following groups: (1) no treatment (control group); (2) BCP soaked in rhBMP-2 and then covered with a resorbable CM; and (3) BCP soaked in rhBMP-2. Following euthanasia, histologic, histomorphometric, and biomechanical assessments of the calvarial specimens were performed to assess bone regeneration. The results showed islands of newly formed bone (NFB) between the defect edges in the control group. NFB was observed bridging the defect edges and around the remnants of BCP in the rhBMP-2 + BCP + CM group and only around the BCP remnants in the rhBMP-2 + BCP group. Histomorphometric analysis revealed a significantly higher mean ± standard deviation (SD) percentage of NFB per defect in the rhBMP-2 + BCP + CM group (46.12 ± 2.56) compared with the control (11.79 ± 0.75) and rhBMP-2 + BCP (26.65 ± 1.48) groups. Although no differences were found in the hardness and elastic modulus (EM) of NFB between the rhBMP-2 + BCP + CM (hardness: 687.78 ± 4.74 MPa; EM: 27.71 ± 0.063 GPa) and the rhBMP-2 + BCP (hardness: 637.65 ± 6.32 MPa; EM: 21.49 ± 0.095 GPa) groups, the biomechanical parameters of NFB in the control group (hardness: 286.17 ± 9.49 MPa; EM: 12.62 ± 0.048 GPa) were significantly less. The experiment demonstrated the efficiency of rhBMP-2 + BCP in GBR, wherein the presence of CM leads to a greater percentage of new bone formation within standardized calvarial defects.

The aim of the present in vivo microcomputed tomographic (μCT), histologic, and biomechanical study was to assess the efficacy of bone marrow-derived mesenchymal stem cells (BMSCs) for promoting guided bone regeneration (GBR) in a standardized rat calvarial defect model. Forty female Wistar albino rats with a mean age of 7.5 months and mean weight of 275 g were used. Following calvarial exposure under general anesthesia, a full-thickness standardized calvarial defect (4.6 mm in diameter) was created. The study animals were randomly divided into four groups based on biomaterials used for GBR: (1) no treatment (negative control); (2) bone graft alone; (3) bone graft placed in the defect and covered with a collagen membrane (CM); and (4) bone graft soaked in BMSCs and covered with a CM. Bone volume and bone mineral density (BMD) of newly formed bone (NFB) and remnant bone particles were determined at baseline and at 2, 4, 6, 8, and 24 weeks postoperative using real time in vivo μCT. Histologic and biomechanical analyses of calvarial specimens were performed at 24 weeks, when the rats were euthanized. Statistically significant differences in volume and BMD of NFB were observed between and within the groups at different data collection periods. Significant increases in volume and BMD of NFB occurred as early as week 2 in all groups except the negative control. While the greatest volume of NFB was observed in the bone graft + BMSC + CM group, BMD of NFB was significantly higher in the bone graft + CM group. Statistically significant decreases in volume and BMD of remnant bone particles were also observed between the groups. Histologic analysis revealed NFB in all groups. The hardness and elastic modulus of NFB in the bone graft + BMSC + CM group were significantly higher than that in the other groups and also similar to adjacent natural bone. This study shows that using adjunct BMSCs with bone graft and CM for guided bone regeneration in standardized rat calvarial defects resulted in the highest quality and quantity of NFB.

Surface nano- and microtexturing techniques have been used to enhance osseointegration, but how these surfaces work is not well understood. Using the knowledge gained from the cell and molecular biology fields, tissue engineering studies, and their own work, the authors and other researchers have developed surfaces for in vitro and in vivo control of the function of cells and tissues. In the present article, the authors summarize what they know about the process of cell response to surfaces, and what they have done and can do to develop surfaces that control hard- and soft-tissue formation and integration of implants. This article is intended to add to the clinician's understanding of cell and surface interactions, explain why certain surfaces are currently used, and describe what surfaces clinicians may see in the future.

The aim of the present preclinical study was to investigate the capability of a new formulation of biphasic calcium phosphate (BCP) in achieving new bone formation either by itself or in combination with different concentrations of growth factors. Twentyfour 3-month-old male New Zealand white rabbits (weight range, 2.5 to 3.0 kg) that had been bred exclusively for biomedical research purposes and obtained from a licensed vendor were used. Four calvarial defects were created in each animal, for a total of 96 defects. Each defect received alloplastic BCP (Osteon III, Genoss) that was composed of 60% hydroxyapatite and 40% β-tricalcium phosphate) (porosity, ~80%; macropore size, 200 to 400 μm; crystallinity, 95%) combined with different concentrations of recombinant human platelet-derived growth factor BB (rhPDGF-BB), human recombinant basic fibroblast growth factor-2 (rhFGF-2), or recombinant human bone morphogenetic protein-2 (rhBMP-2). A custom-made polycarbonate tube was fixed to each defect site by applying slight pressure, and a mixture of bone graft and growth factor was implanted into the tubes. Data were collected 2, 4, and 8 weeks after creation of the defects to assess early and late healing. Various amounts of newly formed bone and remnant BCP particles formed inside of the tube throughout the study period. The BCP + 0.5 mg/mL rhBMP-2 group exhibited the most bone formation. At 8 weeks, more new bone formation was noted in the Osteon III + rhBMP-2 combined group than in other groups. The present study results indicate that BCP can be combined with different concentrations of rhBMP-2, rhFGF-2, and rhPDGF-BB to produce new bone formation within a polycarbonate tube in calvarial defects in a rabbit model.

The objective of the present real-time in vivo experiment was to assess guided bone regeneration (GBR) in standardized calvarial defects using particulate graft material (Bio-Oss) and β-tricalcium phosphate (β-TCP) with adjunct recombinant human platelet-derived growth factor (rhPDGF) therapy. Eighteen female Sprague-Dawley rats with a mean age and weight of 8 ± 0.53 weeks and 250 ± 0.49 g, respectively, were used. Following surgical exposure, a full-thickness standardized calvarial defect was created on the parietal bone using a trephine drill with an outer diameter of 4.6 mm. For treatment, rats were randomly divided into three groups (six rats per group): (1) control; (2) rhPDGF + Bio-Oss, and (3) rhPDGF + β-TCP. Volume of newly formed bone (NFB), bone mineral density (BMD) of NFB, volume of remnant bone particles, and BMD of remnant bone particles were assessed using in vivo microcomputed tomography. Measurements were made at baseline and at 2, 4, 6, and 10 weeks after the surgical procedures. At 10 weeks, all animals were sacrificed and calvarial tissues were assessed histologically. In the control group, a significant increase in BMD of NFB was observed at 6 weeks (mean ± standard deviation [SD], 0.32 ± 0.002 g/mm3) (P .01) from baseline, and the defect did not regenerate completely. In the rhPDGF + Bio-Oss group, mean ± SD volume (2.40 ± 0.25 mm3) (P .01) and BMD (0.13 ± 0.01 g/mm3) of NFB significantly increased at 4 weeks and 6 weeks, respectively, from baseline (P .001). In the rhPDGF + β-TCP group, mean ± SD volume (2.01 ± 0.7 mm3) and BMD (0.12 ± 0.02 g/mm3) of NFB significantly increased at 4 weeks from baseline (P .01). In the rhPDGF + Bio-Oss and rhPDGF + β-TCP groups, mean ± SD BMD of remnant bone particles (0.31 ± 0.11 g/mm3 and 0.23 ± 0.01 g/mm3) showed significant reduction at 6 and 10 weeks, respectively, compared with baseline values (1.12 ± 0.06 g/mm3 and 0.92 ± 0.01 g/mm3, respectively) (P .001). Histologic results at 10 weeks showed NBF in the rhPDGF + Bio-Oss and rhPDGF + β-TCP groups. In real time assessment, when rhPDGF was added to β-TCP, BMD and bone hardness significantly increased compared with the other two groups.

This study aimed to test the null hypothesis that platelet-rich fibrin (PRF), as an immediate postextraction graft material, produces bone that is histomorphometrically no different than bone derived from healing without intervention. The authors compared split-mouth human bone biopsy specimens derived from PRF with bone that had healed without intervention. Eight human bone biopsies were successfully harvested from four patients. The mean ± standard deviation (SD) percent of newly formed osteoid was 9.9% ± 5.9% for specimens derived from PRF, and 4% ± 2.1% for specimens derived from the control sites (P = .089; 95% confidence interval [CI] 4.5-18.1 and 1.6-6.6, respectively). Mean ± SD percent of new mineralized bone was 40.8% ± 10.3% for the PRF specimens and 43.9% ± 16.8% for the control specimens (P = .72, 95% CI, 33.4-55.6 and 19.3-55.5, respectively). Newly formed bone to fibrovascular tissue ratios for specimens in the PRF and control groups were 51%:49% and 48%:52%, respectively. Within the limitations of this study, the null hypothesis could not be rejected. Bone derived from PRF histologically did not differ from bone that healed without intervention.

This retrospective study with a follow-up period of 4 months to 10 years evaluated survival, success, and complication rates of implants placed using osteotome sinus floor elevation (OSFE) without added bone grafting. A total of 926 implants were placed, including 530 short implants (6 mm to 8.5 mm) and 209 implants in low residual bone height (RBH) ( 5 mm). Bone levels were evaluated at approximately 3 months and at 1, 3, and 5 years, and in some cases up to 10 years after implants were placed. The implant survival rate was 98.3% at the 5-year follow-up. Twelve of the 926 implants failed (6 preprosthetic, 6 postprosthetic). The success rate was 95.4% at a threshold of less than 1 mm of bone loss for combined systems (Straumann; Nobel Biocare). Short implant survival and success rates were statistically comparable to conventional-length implants. Low-RBH implants had a lower but acceptable survival rate of 95.7%. Adverse events were rare, with one case of infection and zero cases of vertigo reported. The findings of this study indicate that implant placement with OSFE without added bone graft is highly successful, even when short implants are used in low RBH.

Guided bone regeneration (GBR) using a porcine-derived collagen matrix (Mucograft [MG], Geistlich) has not yet been reported. The aim of this histologic and biomechanical study was to compare the efficacy of MG versus resorbable collagen membranes (RCMs) in facilitating GBR around standardized rat calvarial defects. Forty female Wistar albino rats with a mean age and weight of 6 to 9 weeks and 250 to 300 g, respectively, were used. With the rats under general anesthesia, the skin over the calvaria was exposed using a full-thickness flap. A 4.6-mm-diameter standardized calvarial defect was created in the left parietal bone. For treatment, the rats were randomly divided into four groups (n = 10 per group): (1) MG group: the defect was covered with MG; (2) RCM group: the defect was covered with an RCM; (3) MG + bone group: the defect was filled with bone graft particles and covered by MG; and (4) RCM + bone group: the defect was filled with bone graft particles and covered by an RCM. Primary closure was achieved using interrupted resorbable sutures. The animals were sacrificed at 8 weeks after the surgical procedures. Qualitative histologic analysis and biomechanical assessment to identify hardness and elastic modulus of newly formed bone (NFB) were performed. Collected data were statistically analyzed using one-way analysis of variance. Histologic findings revealed NFB with fibrous connective tissue in all groups. The quantity of NFB was highest in the RCM + bone group. Statistically significant differences in the hardness (F = 567.69, dfN = 3, dfD = 36, P .001) and elastic modulus (F = 294.19, dfN = 3, dfD = 36, P .001) of NFB were found between the groups. Although the RCM + bone group had the highest mean ± standard deviation (SD) hardness of NFB (531.4 ± 24.9 MPa), the RCM group had the highest mean ± SD elastic modulus of NFB (18.63 ± 1.89 GPa). The present study demonstrated that RCMs are better than MG at enhancing new bone formation in standardized rat calvarial defects when used along with mineralized particulate graft material.

The aim of this in vivo microcomputed tomographic (μCT) study was to compare the efficacy of Mucograft (MG) vs resorbable collagen membranes (RCMs) in facilitating guided bone regeneration (GBR) around standardized calvarial defects in rats. Forty female Wistar albino rats with a mean age and weight of 6 to 9 weeks and 250 to 300 g, respectively, were used. With the rats under general anesthesia, the skin over the calvaria was exposed using a full-thickness flap. A standardized calvarial defect with a 4.6-mm diameter was created in the left parietal bone. For treatment, the rats were randomly divided into four groups (n = 10 per group): (1) defects covered with MG (MG group); (2) defects covered with an RCM (RCM group); (3) defects filled with xenograft bone particles and covered by MG (MG + bone group); and (4) defects filled with xenograft bone particles and covered by an RCM (RCM + bone group). Primary closure was achieved using interrupted resorbable sutures. The animals underwent high-resolution, three-dimensional μCT scans at baseline and at 2, 4, 6, and 8 weeks after the surgical procedures. Data regarding volume and bone mineral density (BMD) of newly formed bone (NFB) and bone particles revealed an increase in the volume of NFB in all the groups from baseline to 8 weeks. The MG group had the lowest volume of NFB (mean ± standard deviation [SD], 1.32 ± 0.22 mm3). No significant differences in mean ± SD values for volume of NFB were observed between the RCM (3.50 ± 0.24 mm3) and MG + bone (3.87 ± 0.36 mm3) groups, but their values were significantly lower than that of the RCM + bone group (2.95 ± 0.15 mm3, F = 131.91, dfN = 2, dfD = 27, P .001). Significant differences in BMD of NFB between the groups (F = 332.46, dfN = 3, dfD = 36, P .001) and during different data collection periods (F = 97.04, dfN = 3, dfD = 36, P .01) were observed, with the RCM group having the highest mean ± SD BMD of NFB (0.42 ± 0.05 g/mm3). Significant differences in the bone particle volume between the RCM + bone and MG + bone groups (F = 91.04, dfN = 1, dfD = 18, P .05) and at different data collection periods (F = 314.12, P .01) were observed, with the RCM + bone group displaying greater reduction in both volume (36.8%) and BMD (19.7%) of bone particles. The present in vivo μCT study demonstrated that RCM is better than MG in enhancing new bone formation in rat calvarial standardized defects when used in combination with mineralized particulate graft material.

Different corticotomy surgical procedures have been developed to shorten orthodontic treatment times by stimulating bone remodeling. Although all corticotomy procedures involve physical injury to the bone, the clinical outcomes can vary. Using an ex vivo calvarial bone organ culture model system, the authors evaluated the biologic response of bone to different corticotomies. Bone injuries were generated in 276 calvaria dissected from 5- to 7-day-old neonatal mice using a piezoelectric knife, a bur, and a handheld screw device. The responses were evaluated using chemical, biochemical, and global histomorphometric analyses. Injuries generated by the three approaches induced varying degrees of bone remodeling activities; however, the piezoelectric knife led to the most extensive impact in both bone resorption and formation models.

In vivo microcomputed tomography (μCT) enables real-time assessment of bone regeneration. The aim of this μCT and histologic experiment was to assess guided bone regeneration (GBR) around standardized calvarial defects in rats using particulate graft material (Bio-Oss) with and without collagen membranes (CMs). Eighteen female Sprague- Dawley rats aged 6 weeks and weighing 300 g were used. With the rats under general anesthesia, calvaria were exposed and a full-thickness standardized defect was created on the parietal bone. For treatment, rats were randomly assigned to the following three groups: (1) CM group; (2) Bio-Oss group; and (3) Bio-Oss + CM group. Bone volume and bone mineral density (BMD) of newly formed bone (NFB) and remnant bone particles were measured at baseline and 2, 4, 6, and 10 weeks after the operations using real-time in vivo μCT. At 10 weeks, all animals were sacrificed and calvarial tissues were assessed histologically. In the CM group, a significant increase in mean ± standard deviation (SD) BMD of NFB was observed at 6 weeks (0.32 ± 0.02 g/mm3) (P .01) compared with baseline. In the Bio-Oss group, mean ± SD volume (3.03 ± 0.14 mm3) (P .05) and BMD (0.14 ± 0.01 g/mm3) of NFB significantly increased at 6 weeks compared with baseline (P .01). In the Bio-Oss + CM group, mean ± SD volume (0.98 ± 0.19 mm3) and BMD (0.13 ± 0.01 g/mm3) of NFB significantly increased at 4 weeks compared with baseline (P .01). In th Bio-Oss + CM group, mean ± SD volume (3.5 ± 0.7 mm3) and BMD (0.44 ± 0.03 g/mm3) of remnant bone particles were significantly reduced at 10 weeks compared with baseline values (5.8 ± 0.96 mm3 and 1.3 ± 0.02 g/mm3) (P .05). Although histologic analysis revealed NFB in all the study groups, the Bio-Oss + CM group exhibited the most. The results of this study revealed that, in real time, new bone formation starts as early as 4 weeks in standardized calvarial defects undergoing GBR with Bio-Oss + CM, compared with new bone formation at 6 weeks in defects undergoing GBR with Bio-Oss alone.

In the present case report, the authors describe radiographic and histologic observations of a bone void that formed after a sinus augmentation using a graft material that contained recombinant human bone morphogenetic protein-2 (rhBMP-2) and discuss clinical and histologic implications of their findings. Sinus augmentation was performed using a graft material comprising 1 g of hydroxyapatite/β-tricalcium phosphate, which contained 1 mg of rhBMP-2. Radiographic evaluation was conducted with panoramic radiographs and computed tomography images of the augmented maxillary sinus, which were analyzed using a three-dimensional image-reconstruction program. Histologic evaluation was also performed on a biopsy specimen obtained 6 months after the sinus augmentation. The total augmented volume increased from 1,582.2 mm3 immediately after the sinus augmentation to 3,344.9 mm3 at 6 months after the augmentation because of the formation of a bone void. Twenty-six months after the sinus augmentation, the bone void remained but had reduced in volume, with the total augmented volume reduced to 2,551.7 mm3. Histologically, new bone was observed to be in contact with the grafted particles, and a fatty marrow-like tissue was present in the area of the bone void. This case report shows that the bone void that had formed after sinus augmentation resolved over time and seemed to be partially replaced with new bone. Furthermore, none of the implants failed, and clinical adverse events were not observed during the follow-up period.

The aim of this in vivo microcomputed tomographic (μCT) experiment was to assess in real time the efficacy of a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) and biphasic calcium phosphate (BCP), with and without resorbable collagen membrane (CM), in regeneration of standardized calvarial defects (SCDs) in rats. A total of 30 female Wistar albino rats (n = 10/group) with a mean age and weight of 7.5 months and 275 g, respectively, were used. With the rats under general anesthesia, the calvaria were exposed using full-thickness periosteal flaps and unilateral SCDs of 4.6 mm diameter were created on the left parietal bone. Defects were left untreated (control group) or randomly filled with either BCP soaked in rhBMP-2 and then covered with CM (BMP + BCP + CM group) or BCP soaked in rhBMP-2 alone (BMP + BCP group). In vivo μCT scans were done at baseline and 2, 4, 6, and 8 weeks. Newly formed bone (NFB) and remaining BCP particles were assessed for their volumes (NFBV, BCPV, respectively) and mineral densities (NFBMD, BCPMD, respectively). In vivo μCT results showed scanty amounts of new bone at the peripheries of the defect in the control group. In the other two groups, near complete defect closure was evident at 8 weeks. The mean NFBV after 8 weeks was 4.63 ± 0.96 mm3, 11.82 ± 1.17 mm3, and 13.85 ± 1.89 mm3 for the control, BMP + BCP + CM, and BMP + BCP groups, respectively. After 8 weeks, the mean NFBMD was 0.38 ± 0.03 g/mm3, 0.24 ± 0.07 g/mm3, and 0.35 ± 0.03 g/mm3 for the control, BMP + BCP + CM, and BMP + BCP groups, respectively. After 8 weeks, the mean BCPV and BCPMD values for the BMP + BCP + CM and BMP + BCP groups were 2.73 ± 0.65 mm3, 0.33 ± 0.08 g/mm3, 2.49 ± 0.71 mm3, and 0.28 ± 0.03 g/mm3, respectively. The present real-time in vivo μCT experiment demonstrated that BMP + BCP, either with or without CM, was effective in promoting bone regeneration within rat SCDs and enabled new bone formation starting as early as 2 weeks.

The aim of the present in vivo microcomputed tomography (μCT) and histologic experiment was to assess the efficacy of guided bone regeneration (GBR) around standardized calvarial defects using recombinant human platelet-derived growth factor (rhPDGF) with and without resorbable collagen membrane (RCM). A total of 50 female Wistar albino rats with a mean age of 7.5 months and mean weight of 275 g were used. The calvarium was exposed following midsagittal scalp incision and flap reflection. A full-thickness standardized calvarial defect (4.6 mm diameter) was created. Study animals were randomly divided into five groups based on biomaterials used for GBR within the defect: (1) no treatment (negative control), (2) bone graft alone (BG), (3) bone graft covered by RCM (BG + RCM), (4) bone graft soaked in rhPDGF (BG + rhPDGF), and (5) bone graft soaked in rhPDGF and covered with RCM (BG + rhPDGF + RCM). In vivo μCT for determination of newly formed bone volume (NFBV) and mineral density (NFBMD) and remnant bone particles volume (RBPV) and mineral density (RBPMD) was done at baseline and at 2, 4, 6, and 8 weeks postoperatively. Eight weeks following surgery, the animals were sacrificed and harvested calvarial specimens were subjected to histologic and biomechanical analysis. There was an increase in NFBV and NFBMD associated with a corresponding decrease in RBPV and RBPMD in all the study groups. Two-way analysis of variance revealed significant differences in the measured values within and between the groups across the timelines examined during the study period (P .05). While the NFBV was significantly higher in the bone graft, BG + RCM, and BG + rhPDGF + RCM groups, the NFBMD was similar in all the groups except negative control. The greatest decreases in RBPV and RBPMD were observed in the BG + rhPDGF + RCM group in comparison to the other groups. Similarly, BG + rhPDGF + RCM groups had hardness and elastic modulus similar to that of natural bone. The in vivo μCT results were validated by the qualitative histologic findings. In real time, new bone formation starts as early as 2 weeks in rat calvarial defects treated with bone graft and rhPDGF, irrespective of the presence or absence of RCM.