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A comparison of synthetic hydroxyapatite/silica oxide, xenogenic hydroxyapatite-based bone substitute materials with empty control sites in terms of bone regeneration enhancement in a rabbit calvarial four non-critical-sized defect model. In each of six rabbits, four bicortical calvarial bone defects were generated. The following four treatment modalities were randomly allocated: (1) empty control site, (2) synthetic hydroxyapatite/silica oxide-based (HA/SiO) test granules, (3) xenogenic hydroxyapatite -based granules, (4) synthetic hydroxyapatite/silica oxide -based (HA/SiO) test two granules. The results of the latter granules have not been reported due to their size being three times bigger than the other two granule types. After 4 weeks, the animals were sacrificed and un-decalcified sections were obtained for histological analyses. For statistical analysis, the Kruskal-Wallis test was applied ( P<0.05). Histomorphometric analysis showed an average area fraction of newly formed bone of 12.32±10.36% for the empty control, 17.47±6.42% for the xenogenic hydroxyapatite -based granules group, and 21.2±5.32% for the group treated with synthetic hydroxyapatite/silica oxide -based granules. Based on the middle section, newly formed bone bridged the defect to 38.33±37.55% in the empty control group, 54.33±22.12% in the xenogenic hydroxyapatite -based granules group, and to 79±13.31% in the synthetic hydroxyapatite/silica oxide -based granules group. The bone-to-bone substitute contact was 46.38±18.98% for the xenogenic and 59.86±14.92% for the synthetic hydroxyapatite/silica oxide-based granules group. No significant difference in terms of bone formation and defect bridging could be detected between the two bone substitute materials or the empty defect. There is evidence that the synthetic hydroxyapatite/silica oxide granules provide comparable results with a standard xenogenic bovine mineral in terms of bone formation and defect bridging in non-critical size defects. Kruse A, Jung RE, Nicholls F, Zwahlen RA, Hämmerle CHF, Weber FE. Bone regeneration in the presence of a synthetic hydroxyapatite/silica oxide -based and a xenogenic hydroxyapatite -based bone substitute material. Clin. Oral Impl. Res. , 2011; 506-511 doi: 10.1111/j.1600-0501.2010.02039.x [ABSTRACT FROM AUTHOR]

Objectives: The aim of the present randomized, controlled clinical multicenter trial was to compare a polyethylene glycol (PEG) and a native collagen membrane (BG) for simultaneous guided bone regeneration at bony dehiscence‐type defects around bone level titanium implants. Material and methods: The study enrolled 117 patients requiring implant treatment in the posterior maxilla or mandible with expected buccal bony dehiscence‐type defects at the placed titanium implants. According to a parallel groups design, defects were filled with a synthetic bone filler and randomly assigned to either PEG or BG membrane. As primary parameter, the relative vertical bone fill was assessed at baseline and at re‐entry after 6 months of healing. As secondary parameters, the marginal bone level (MBL) was assessed radiographically and soft tissue conditions were recorded up to 18 months postloading. Results: Both groups showed comparable vertical bone fill revealing a relative change in defect height of 59.7% (PEG) and 64.4% (BG). The absolute mean reduction in defect size was 2.5 mm in the PEG group and 3.2 mm in the BG group. Although both groups revealed a statistically significant mean defect reduction (p <.001), a comparison between the two groups did not show statistical significances. The non‐inferiority test with inferiority limit of −5% could not be rejected, based on the 90% confidence interval of the differences of the two means with lower limit −15.4%. After 18 months, an MBL increase of 0.45 ± 0.43 mm in the PEG group and 0.41 ± 0.81 mm in the BG group was detected (p <.001). Soft tissue complications were observed in both groups without showing statistical significance. Conclusions: Both membranes supported bone regeneration at dehiscence‐type defects and obtained vertical bone fill with a relative change in defect height of 59.7% (PEG) and 64.4% (BG); however, the non‐inferiority of PEG could not be shown. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this randomized controlled trial was to compare alveolar ridge preservation using a bone substitute material and covered with a synthetic or porcine collagen membrane. Materials and methods: Thirty‐two sockets in the aesthetic maxillary region of 30 patients were randomized into two groups. Randomization was stratified according to bone wall defect. Flapless technique was used, and sockets were grafted with bi‐phasic calcium phosphate particulate bone substitute and covered by synthetic polyethylene glycol (PEG; test group) or porcine‐derived collagen membrane (CM; control group). No primary closure was attempted. A cone beam computed tomography (CBCT) scan was performed immediately after the surgical procedure and repeated 22 weeks later. OnDemand3D was used to superimpose scan images and assess changes. The mean vertical and horizontal percentage bone loss were calculated and implants placed after 6 months with or without additional augmentation. Results: There were no baseline differences between groups or dropouts. The mean percentage loss at the labial plate and at the coronal part of the sockets was statistically significantly lower in the test group compared with controls (−2.86% [SD = 13.48] versus 7.42% [SD = 11.95]; 13.45% [SD = 11.97] versus 28.59% [SD = 16.97]). Implants were placed after 6 months, and there was no difference in need for further augmentation between PEG (n = 5) or CM (n = 4). Conclusion: Sites treated with PEG membrane showed less percentage loss in horizontal and vertical measurements in this trial. [ABSTRACT FROM AUTHOR]

Background. Endoscopy has seen a significant development over recent years in various medical fields with its application expanding from the support of minimal invasive surgery to in situ imaging. In this context, the application of endoscopic techniques to assess the quality of the regenerated bone in situ in the drill hole before implant placement is an appealing approach. Aim. The aim of this study was to use short distance support immersion endoscopy (SD-SIE) to compare the quality of regenerated bone in healed postextraction sites, which are grafted with an in situ hardening β-TCP, against ungrafted sites, before implant placement. This assessment was based on microscopic bone analysis in combination with the blood vessel count. Method. 13 spontaneously healed and 13 grafted postextraction sites in 3 men and 6 women, aged 26–83 years, were evaluated using SD-SIE after 4–6 months. SD-SIE was applied in drill holes before implant placement, and videos were taken from representative central buccal areas. The video recordings were analyzed using Image J software for (1) number of blood vessels per area (NBV), (2) relative area of vessels (VA), (3) relative area of mineralized bone (MBA), (4) relative area of unmineralized bone (UMBA), and (5) relative area of bone substitute (BSA). Results. The grafted sites showed more (1) NBV as well as (2) VA (8.6 ± 1.1; 2.03 ± 0.28%) than the ungrafted sites (2.5 ± 0.6; 1.18 ± 0.36%) (independent t-test; p<0.05); (3) MBA and (4) UMBA were similar to those in the grafted sites (86.3 ± 2.2 %; 13.7 ± 2.2 %) and to the ungrafted sites (89.5 ± 3.7%; 10.5 ± 3.6%) (independent t-test; p>0.05); and (5) BSA in the grafted sites was 18.2 ± 5.4%. Conclusion. SD-SIE is an interesting new approach for in situ assessment of bone quality and blood supply before implant placement. The regenerated bone in β-TCP grafted extraction sockets showed an increased vascularization compared to ungrafted sites providing a vital support for subsequent implant placement. [ABSTRACT FROM AUTHOR]

Objectives: Recently, a new liquid carrier system for enamel matrix derivate (EMD‐liquid) was developed with better physico‐chemical properties for improved adsorption of EMD to biomaterial surfaces. The aim of the present study was to investigate the bone regenerative potential of EMD‐liquid in combination with a natural bone mineral (NBM) in vivo. Methods: Four 6‐mm defects were created in the calvaria of six New Zealand white rabbits. Defects were filled with either (1) control (empty), (2) 20 mg of NBM, or (3) 20 mg of NBM + 20 µl of EMD‐liquid (n = 8). All defects were covered with collagen barrier membranes. The bone regenerative potential was investigated by micro‐CT and histomorphological analyses at 8 weeks postsurgery. Results: The mineralized tissue volume was significantly higher in the NBM + EMD‐liquid group when compared to control, whereas no difference was observed between the NBM alone and control groups. While no significant difference was observed for horizontal bone defect closure between the NBM + EMD‐liquid and the NBM alone groups, NBM + EMD‐liquid significantly increased the total mineralized area and reduced the percentage of soft/connective tissue infiltration. No statistically significant difference was observed between the NBM + EMD‐liquid group and NBM alone group for amount of mineralized bone. Conclusion: The addition of EMD‐liquid did not lead to statistically significant bone formation when compared to NBM alone. The combination of NBM + EMD‐liquid but not NBM alone did however induce superior mineralized tissues when compared to control (empty). Further research investigating the adsorption potential of EMD‐liquid to bone‐grafting particles with/without collagen may provide valuable insights into future regenerative strategies with enamel matrix proteins. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effectiveness of adding leukocyte and platelet‐rich fibrin (L‐PRF) to deproteinized bovine bone mineral (DBBM) for early implant placement after maxillary sinus augmentation. Materials and Methods: Twelve patients requiring two‐stage bilateral maxillary sinus augmentation were enrolled to the study. The elevated sinus cavities were randomly grafted with DBBM + L‐PRF (test) or DBBM alone (control) in a split‐mouth design. Implants were placed in the augmented sites after 4 months in the test group and 8 months in the control group. Bone biopsies were collected during implant placement for histomorphometric evaluation. Resonance frequency analysis was performed immediately after implant placement and at implant loading in both groups. Cone‐beam computed tomography was obtained preoperatively and postoperatively for evaluation of graft volume changes. Results: Both procedures were effective for maxillary sinus augmentation. Cone‐beam computed tomography analysis did not reveal differences in graft volume between test and control group at any of the evaluated time points (P > .05). Histological evaluation demonstrated increased percentage of newly formed bone for the test group (44.58% ± 13.9%) compared to the control group (30.02% ± 8.42%; P = .0087). The amount of residual graft in the control group was significantly higher (13.75% ± 9.99%) than in the test group (3.59 ± 4.22; P = .0111). Implant stability quotient (ISQ) immediately after implant placement was significantly higher in the control group (75.13 ± 5.69) compared to the test group (60.9 ± 9.35; P = .0003). The ISQ values at loading did not differ between the groups (P = .8587). Implant survival rate was 100% for both groups. Conclusion: The addition of L‐PRF to the DBBM into the maxillary sinus allowed early implant placement (4 months) with increased new bone formation than DBBM alone after 8 months of healing. [ABSTRACT FROM AUTHOR]

Aims: To perform a systematic literature review of the regenerative potential of bone substitutes used to fill critical size defects (CSDs) in rabbit calvariae; to determine the quality of the included studies using ARRIVE guidelines. Material and methods: An Internet search was performed in duplicate using MEDLINE, PubMed and Google Scholar databases (without restrictions on publication date) for studies reporting the regenerative potential of bone substitutes in CSDs in rabbit calvariae. Four parameters were analyzed by histomorphometry: new bone formation (NB); defect closure (DC); residual graft (RG); and connective tissue (CT). Animal Research Reporting in In Vivo Experiments (ARRIVE) guidelines (a list of 20 aspects for scoring texts and ensuring comparison between different experimental studies in animals) were used to evaluate the quality of the selected works. Results: Twenty‐one manuscripts were included. CSDs with 15 mm were predominant (57.14%). Only one study described the four histomorphometric parameters. NB formation was analyzed in 15 studies (71.42%) and was higher for particulate autogenous bone grafts (range 52.1–82%) after 12 weeks. DC was evaluated in six studies (28.57%) and was higher for fragmented adipose tissue grafts (range 53.33–93.33%) after 12 weeks. RG was evaluated in four studies (19.04%) and was higher for hydroxyapatite/beta‐tricalcium phosphate grafts with silica (HA/ß‐TCP + Si) (range 35.78–47.54%) at 12 weeks. CT was evaluated in two studies (9.5%) and was higher for HA/ß‐TCP + membrane (44.2%) at 12 weeks. Quality evaluation identified three items (title, introduction/objectives and experimental procedure) (15%) with excellent scores, 10 items (abstract, introduction/background, methods/ethical statement, experimental animals, experimental outcomes, statistics, results/baseline data, outcome/estimation and discussion interpretation/scientific implications) (50%) with average scores, and seven items (housing and husbandry, sample size, allocation, numbers analyzed, adverse effects, general applicability/relevance and funding) (35%) obtained poor scores. Only one manuscript obtained a quality evaluation considered as excellent. Conclusions: Autogenous bone grafts increase NB. DC is enhanced by the use of fragmented adipose tissue. RG remains in the defect for longer when hydroxyapatite/beta‐tricalcium phosphate with silica is used, and more CT can be expected when hydroxyapatite/beta‐tricalcium phosphate with silica grafts are covered by a membrane. The addition of stem cells of different origins to grafting materials enhances bone formation in early healing periods. The ARRIVE guidelines are still insufficiently used and the overall quality of studies remains low. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The objective of this study was to determine the effect of bone morphogenetic protein‐2 (BMP‐2) mixed with either polyethylene glycol hydrogel or synthetic bone substitute (SBS) on new bone formation in peri‐implant dehiscence defects after 16 weeks of healing. Materials and methods: A guided bone regeneration procedure was performed in box‐type peri‐implant defects that were surgically prepared in six beagle dogs. The following four experimental groups were used (i) control (no graft), (ii) SBS+hydrogel, (iii) SBS+BMP‐2/hydrogel and (iv) BMP‐2/SBS+hydrogel. Volumetric analysis using micro‐computed tomography and histomorphometric analysis was performed at 16 weeks post‐operatively. Results: The amount of new bone and the total augmented volume did not differ significantly between both BMP‐treated groups and the SBS+hydrogel group (p > .05). Likewise, no histometric differences were observed in the values of new bone area and bone‐to‐implant contact ratio among the three augmentation groups (new bone area: 0.06 ± 0.08, 0.19 ± 0.20, 0.48 ± 0.37 and 0.56 ± 0.60 mm2 [mean ± standard deviation] in groups 1–4, respectively; bone‐to‐implant contact: 9.44 ± 11.51%, 19.91 ± 15.19%, 46.31 ± 29.82% and 42.58 ± 26.27% in groups 1–4, respectively). Conclusion: The osteogenic efficacy of BMP‐2 on the regeneration of peri‐implant bone defects was not detectable after 16 weeks regardless of the carrier materials. [ABSTRACT FROM AUTHOR]

Objectives To test whether or not chemical and/or physical modifications of polyethylene glycol ( PEG) hydrogels influence degradation time, matrix/membrane stability, and integration into surrounding hard and soft tissues. Material and methods In 28 rabbits, six treatment modalities were randomly applied to six sites on the rabbit skull: a dense network PEG hydrogel ( PEG HD), a medium-dense network PEG hydrogel ( PEG MD), a medium-dense network PEG hydrogel modified with an RGD sequence ( PEG MD/ RGD), a medium-dense network PEG hydrogel modified with RGD with reduced carboxymethyl cellulose ( PEG MD/ RGD_ LV), a loose network PEG hydrogel modified with RGD ( PEG LD/ RGD), and a collagen membrane ( BG). Descriptive histology and histomorphometry were performed at 1, 2, 4, and 6 weeks. Results PEG HD revealed the highest percentage of residual matrix at all time points starting with 47.2% (95% CI: 32.8-63.8%) at 1 week and ending with 23.4% (95% CI: 10.3-49.8%) at 6 weeks. The hydrogel with the loosest network ( PEG LD/ RGD) was stable the first 2 weeks and then degraded continuously with a final area of 8.3% (95% CI: 3.2-21.2%). PEG HD was the most stable and densely stained membrane, whereas PEG MD and PEG LD matrices integrated faster, but started to degrade to a higher degree between 2 and 4 weeks. PEG MD degradation was dependent on the addition of RGD and the amount of CMC. Conclusions Chemical and/or physical modifications of PEG hydrogels influenced matrix stability. PEG MD/ RGD demonstrated an optimal balance between degradation time and integration into the surrounding soft and hard tissues. [ABSTRACT FROM AUTHOR]

Objectives The aim of the study was to test whether or not the use of a polyethylene glycol (PEG) hydrogel with or without the addition of an arginylglycylaspartic acid (RGD) sequence applied as a matrix in combination with hydroxyapatite/tricalciumphosphate (HA/TCP) results in similar peri-implant bone regeneration as traditional guided bone regeneration procedures. Material and methods In 12 beagle dogs, implant placement and peri-implant bone regeneration were performed 2 months after tooth extraction in the maxilla. Two standardized box-shaped defects were bilaterally created, and dental implants were placed in the center of the defects with a dehiscence of 4 mm. Four treatment modalities were randomly applied: i)HA/ TCP mixed with a synthetic PEG hydrogel, ii)HA/ TCP mixed with a synthetic PEG hydrogel supplemented with an RGD sequence, iii)HA/ TCP covered with a native collagen membrane ( CM), iv)and no bone augmentation (empty). After a healing period of 8 or 16 weeks, micro- CT and histological analyses were performed. Results Histomorphometric analysis revealed a greater relative augmented area for groups with bone augmentation (43.3%-53.9% at 8 weeks, 31.2%-42.8% at 16 weeks) compared to empty controls (22.9% at 8 weeks, 1.1% at 16 weeks). The median amount of newly formed bone was greatest in group CM at both time-points. Regarding the first bone-to-implant contact, CM was statistically significantly superior to all other groups at 8 weeks. Conclusions Bone can partially be regenerated at peri-implant buccal dehiscence defects using traditional guided bone regeneration techniques. The use of a PEG hydrogel applied as a matrix mixed with a synthetic bone substitute material might lack a sufficient stability over time for this kind of defect. [ABSTRACT FROM AUTHOR]

In this study, bisphasic calcium phosphate (BCP) and two types of polysaccharide, carboxymethyl cellulose (CMC) and hyaluronic acid (HyA), were used to fabricate composite block bone grafts, and their physical and biological features and performances were compared and evaluated in vitro and in vivo. Specimens of the following were prepared as 6 mm diameter, 2 mm thick discs; BPC mixed with CMC (the BCP/CMC group), BCP mixed with crosslinked CMC (the BCP/c-CMC group) and BCP mixed with HyA (the BCP/HyA group) and a control group (specimens were prepared using particle type BCP). A scanning electron microscope study, a compressive strength analysis, and a cytotoxicity assessment were conducted. Graft materials were implanted in each of four circular defects of 6 mm diameter in calvarial bone in seven rabbits. Animals were sacrificed after four weeks for micro-CT and histomorphometric analyses, and the findings obtained were used to calculate new bone volumes (mm3) and area percentages (%). It was found that these two values were significantly higher in the BCP/c-CMC group than in the other three groups (p < 0.05). Within the limitations of this study, BCP composite block bone graft material incorporating crosslinked CMC has potential utility when bone augmentation is needed. [ABSTRACT FROM AUTHOR]

Objectives The objective of this experiment was to test whether or not a synthetic bone substitute ( SBS) was more effective than a polyethylene glycol hydrogel as a carrier material for bone morphogenetic protein-2 ( BMP-2) when attempting to regenerate bone. Material and methods Two identical, box-type dehiscence defects (4 × 4 mm buccolingually and apicocoronally, and 8 mm mesiodistally) were surgically prepared on buccal sides of the left and right edentulous ridge in five beagle dogs. Following implant placement, the defects either received (i) no graft, (ii) SBS+hydrogel, (iii) SBS+ BMP-2 loaded hydrogel, and (iv) BMP-2-loaded SBS+hydrogel. The animals were euthanized at 8 weeks postsurgery. Radiographic and histomorphometric analyses were performed. Results The hydrogel alone was not able to stabilize the grafted bone particles at 8 weeks, and SBS+hydrogel group did not significantly differ from the control group in all volumetric measurements. On the other hand, extensively regenerated new bone was connected with most of the remaining SBS particles in the BMP-2 groups. The BMP-2 groups exhibited significantly greater new bone formation (10.65 mm3 and 1.47 mm2 in the SBS+ BMP-2-loaded hydrogel group; 14.17 mm3 and 0.93 mm2 in the BMP-2-loaded SBS+hydrogel) than non- BMP-2 groups (1.27 mm3 and 0.00 mm2 in the control group; 2.01 mm3 and 0.19 mm2 in the SBS+hydrogel group) in volumetric and histomorphometric analyses ( P < 0.001). However, there were no significant differences between both BMP-2 groups. Conclusion BMP-2 could yield enhanced bone regeneration in the critical-size peri-implant defects regardless of whether SBS or hydrogel is used for preloading, although the outcomes seem to be more reproducible with BMP-2 preloaded on SBS. [ABSTRACT FROM AUTHOR]

Objective Biphasic calcium phosphates ( BCPs), mixture of hydroxyapatite ( HA) and β-tricalcium phosphate (β- TCP) are synthetic bone substitutes, which are increasingly used in adjunctive implant and periodontal surgery. The aim of this study was to evaluate the rate and amount of bone regeneration in defects filled with three different BCPs in relation to deproteinized bovine bone mineral ( DBBM). Method Ten New Zealand rabbits were used in the experiment. Four defects of 6 mm in diameter were prepared in each rabbit, and they were filled with different biomaterials: BCP with HA/β- TCP ratio of 60/40 ( BCPG1), ratio of 10/90 ( BCPG2), a BCP with polylactide incorporated (moldable BCP) and DBBM. Group A ( n = 5) rabbits were sacrificed after 3 months, and group B ( n = 5) were sacrificed 6 months after surgery. Histological and histomorphometric analyses were performed. Mean percentages of mineralized new bone (% MNB), bone marrow (% BM), residual grafting material (% RG) and soft tissue (% ST) were calculated for each bone substitute. Results Percentages of MNB in defects filled with the four bone substitutes were comparable after 3 months and 6 months. Amount of MNB regenerated for moldable BCP and DBBM after 6 months were significantly higher than after 3 months ( P < 0.05), whereas those for BCPG1 and BCPG2 did not show significant change. Percentage RG was significantly higher in moldable BCP compared with BCPG1 ( P < 0.05) after 3 months. Conclusion After 3 months, the granules-form synthetic materials performed better than DBBM in terms of bone regeneration. The grafting materials performed similarly after 6 months of healing. Addition of polylactide in moldable BCP may slow down osteogenesis in grafted defects. [ABSTRACT FROM AUTHOR]

Aim To test whether or not bone regeneration using deproteinized bovine bone mineral ( DBBM) is comparable to hydroxyapatite/silica oxide ( HA/SiO) and to test the effect of recombinant human bone morphogenetic protein-2 (rh BMP-2) as an adjunct to DBBM for localized bone regeneration. Materials and methods In each of the 10 rabbits, 4 titanium cylinders were placed on the external cortical plates of their calvaria. Four treatment modalities were randomly allocated: (i) empty, (ii) HA/SiO, (iii) DBBM, and (iv) DBBM plus rh BMP-2 ( DBBM/ BMP). The animals were sacrificed at week 8. Descriptive histology and histomorphometric assessment using a superimposed test grid of points and cycloids were performed. Results The mean number of points of the test grid coinciding with bone within the cylinder reached 124 ± 35 bone points for empty controls, 92 ± 40 bone points for DBBM, 98 ± 44 bone points for synthetic HA/SiO, and 146 ± 34 bone points DBBM/ BMP. The P-value for DBBM with and without BMP reached a borderline statistical significance of 0.051. However, the area of bone regeneration within the cylinders peaked for DBBM/ BMP and was statistically significantly higher compared with empty cylinders ( P < 0.05). The bone-to-bone substitute contact ranged between 32.9% ± 21.7 for DBBM, 39.6 ± 18.4% for HA/SiO, and 57.8% ± 10.2 for DBBM/ BMP. The differences between DBBM/ BMP and controls ( DBBM, HA/SiO) were statistically significant ( P < 0.05). Conclusions DBBM and HA/SiO rendered comparable amounts of bone regeneration. The addition of rh BMP-2 to DBBM resulted in more favorable outcomes with respect to the area of bone regeneration and to bone-to-implant contact, thereby indicating the potential of this growth factor to enhance bone regeneration within this animal model. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this controlled clinical study was to compare a polyethylene glycol membrane (PEG) used for bone regeneration of peri-implant defects to a collagen membrane with respect to implant survival rate, dimensions of buccal peri-implant bone and mucosa. Materials and methods: Thirty-seven patients who received single tooth implants with simultaneous guided bone regeneration (GBR) in the posterior maxilla or mandible were enrolled in the study. Intra-operative heights of bone defects were assessed prior to bone augmentation. The defects were augmented with xenogenic bone mineral and randomly covered either with a porcine collagen membrane (control) or with a PEG membrane (test). Five years after implant placement, clinical evaluation and cone beam computed tomography (CBCT) scans were performed. Remaining height of bone defect, horizontal bone thickness, level of mucosal margin, and mucosal thickness were assessed in CBCT images. The difference of height of bone defect at implant placement and at 5-year follow-up was calculated. The differences between the two groups were analyzed using two-sided t-test and Mann-Whitney U-test. Results: After 5 years, 32 patients could be included and exhibited an implant survival rate of 100% for both groups. The buccal vertical bone gain between implant placement and 5-year follow-up amounted at 4.3 ± 1.5 (SD) mm and 4.8 ± 2.6 (SD) mm for the control and the test group, respectively (P = 0.493). Neither the bone height nor the thickness reached statistical significant differences between the two groups. The distance between mucosal margin and implant shoulder resulted in 0.8 ± 0.7 (SD) mm in the control and 0.5 ± 0.8 (SD) mm in the test group (P = 0.198). The mucosal thickness reached 1.4 ± 0.5 (SD) mm in the control and 1.3 ± 0.3 (SD) mm in the test group (P = 0.715). There were no significant correlations between height of bone defect at baseline and at follow-up examination and between different 5-year parameters. Conclusion: A polyethylene glycol membrane used for bone regeneration of peri-implant defects performed as successfully as a collagen membrane with respect to implant survival rate and dimensions of the buccal peri-implant bone and mucosa after 5 years. [ABSTRACT FROM AUTHOR]

Objective To determine the early temporal-wide genome transcription regulation by the surface topography at the bone-implant interface of implants bearing microroughened or superimposed nanosurface topology. Materials and methods Four commercially pure titanium implants (2.2 × 5.0 mm) with either a moderately roughened surface ( Ti Oblast) or super-imposed nanoscale topography ( Osseospeed) were placed ( n = 2/surface) in edentulous sites of eleven systemically healthy subjects and subsequently removed after 3 and 7 days. Total RNA was isolated from cells adherent to retrieved implants. A whole-genome microarray using the Affymetrix Human gene 1.1 ST Array was used to describe the gene expression profiles that were differentially regulated by the implant surfaces. Results There were no significant differences when comparing the two implant surfaces at each time point. However, the microarray identified several genes that were differentially regulated at day 7 vs. day 3 for both implant surfaces. Functionally relevant categories related to the extracellular matrix ( ECM), collagen fibril organization, and angiogenesis were upregulated at both surfaces (day7 vs. day3). Abundant upregulation of several differential markers of alternative activated macrophages was observed (e.g., MRC1, MSR1, MS4 A4 A, SLC38 A6, and CCL18). The biological processes involved with the inflammatory/immune response gene expression were concomitantly downregulated. Conclusions Gene regulation implicating collagen fibrillogenesis and ECM organization as well as the inflammatory/immune responses involving the alternative activated pathway are observed in implant adherent cells at early (3-7 days) after implantation. These gene expression events may indicate a pivotal role of collagen fibrillogenesis as well as immunomodulation in altering bone accrual and biomechanical physical properties of the implant-bone interface. [ABSTRACT FROM AUTHOR]

Objective i) To test whether or not pH modifications of a PEG hydrogel matrix influence degradation time and bone regeneration in acute and unprepared (chronic) defects; and ii) to test whether or not the addition of a PEG hydrogel to hydroxyapatite/tricalciumphosphate (HA/TCP) can further enhance bone regeneration compared to HA/TCP alone in acute defects. Materials and methods In 11 mini-pigs, three acute standardized defects and one chronic site were prepared in each hemi-mandible. The following treatment modalities were applied in acute defects: PEG hydrogel regular (PEG 8.7), PEG hydrogel pH-modified plus (PEG 9.0), PEG hydrogel pH-modified minus (PEG 8.4), PEG 8.7 mixed with HA/TCP granules (PEG-HA/TCP), HA/TCP granules (HA/TCP), and empty control (control). In chronic sites, PEG 8.7 and PEG 9.0 were applied. Subsequently primary wound closure was obtained and animals sacrificed at 10 ( n = 6) and 21 days ( n = 5). Descriptive histology and histomorphometric analyses were performed including measurements for newly formed bone, remaining hydrogel, and percent defect fill. Standard descriptive statistics were calculated, and regression analysis used to determine the difference between treatments, taking into account relevant factors and correction for multiple comparisons. Results In acute defects, the amount of newly formed bone increased statistically significantly over time for all treatments. The increase was higher for PEG 8.7 (35.9%) compared with PEG 8.4 and PEG 9.0 and was higher for PEG- HA/ TCP (24.7%) than for HA/ TCP (14.6%). The remaining hydrogel ranged between 7.6 ± 13.3% for PEG 8.4 and 17.7 ± 12.8% for PEG 8.7 at 10 days. At 21 days, no remaining hydrogel was found except for PEG- HA/ TCP (11.5 ± 10.4%). In chronic sites, at 10 days, the remaining hydrogel covered 29.5 ± 10.3% ( PEG 9.0) and 25.6 ± 21.8% ( PEG 8.7) of the area. At 21 days, the amount of hydrogel (29.7 ± 31.7% for PEG 9.0; 1.4 ± 2.5% for PEG 8.7) decreased, while the amount of bone increased to 14.0 ± 16.3% for PEG 9.0 and to 37.9 ± 15.7% for PEG 8.7. Conclusions The PEG hydrogel matrix with a mid-range pH (PEG 8.7) may serve as a matrix for localized bone regeneration with or without the addition of a bone substitute material. This was demonstrated by enhanced bone regeneration in acute and chronic defects compared with control hydrogels and HA/TCP alone. [ABSTRACT FROM AUTHOR]

Objective To evaluate the radiographic changes of the alveolar ridge following application of different ridge preservation techniques 6 months after tooth extraction. Materials and Methods Four treatment modalities were randomly assigned in 40 patients: β-tricalcium-phosphate-particles with polylactid coating (β- TCP), demineralized bovine bone mineral with 10% collagen covered with a collagen matrix ( DBBM-C/ CM), DBBM-C covered with an autogenous soft-tissue graft ( DBBM-C/ PG) and spontaneous healing (control). Cone-beam computed tomography scans were performed after treatment and 6 months later. Results After 6 months, the vertical changes ranged between −0.6 mm (−10.2%) for control and a gain of 0.3 mm (5.6%) for DBBM-C/ PG on the lingual side, and between −2.0 mm (−20.9%) for β- TCP and a gain of 1.2 mm (8.1%) for DBBM-C/ PG on the buccal side. The most accentuated ridge width changes were recorded 1 mm below the crest: −3.3 mm (−43.3%, C), −6.1 mm (−77.5%, β- TCP), −1.2 mm (−17.4%, DBBM-C/ CM) and −1.4 mm (−18.1%, DBBM-C/ PG). At all three levels, DBBM-C with either CM or PG was not significantly differing ( p > 0.05), while most other differences between the groups reached statistical significance ( p < 0.05). Conclusions Application of DBBM-C, covered with CM or PG, resulted in less vertical and horizontal changes of the alveolar ridge as compared with controls 6 months after extraction. [ABSTRACT FROM AUTHOR]

Objectives: To assess the influence of two barrier membranes and two bone graft substitutes mixed with autogenous bone (AB) on staged guided bone regeneration and osseointegration of titanium implants in dogs. Materials and methods: Four saddle-type defects each were prepared in the upper jaw of six fox hounds and randomly filled with a natural bone mineral (NBM)+AB and a biphasic calcium phosphate (SBC)+AB and allocated to either an in situ gelling polyethylene glycol (PEG) or a collagen membrane (CM). At 8 weeks, modSLA titanium implants were inserted and left to heal in a submerged position. At 8+2 weeks, dissected blocks were processed for histomorphometrical analysis (e.g., treated area [TA], bone-to-implant contact [BIC]). Results: The mean TA values (mm2) and BIC values (%) tended to be higher in the PEG groups(TA: NBM+AB [10.4 ± 2.5]; SBC+AB [10.4 ± 5.8]/BIC: NBM+AB [86.4 ± 20.1]; SBC+AB [80.1 ± 21.5]) when compared with the corresponding CM groups (TA: NBM+AB [9.7 ± 4.8]; SBC+AB [7.8 ± 4.3]/BIC: NBM+AB [71.3 ± 20.8]; SBC+AB [72.4 ± 20.3]). A significant difference was observed for the mean TA values in the SBC+AB groups. Conclusion: It was concluded that all augmentation procedures investigated supported bone regeneration and staged osseointegration of modSLA titanium implants. However, the application of PEG may be associated with increased TA values. To cite this article: Schwarz F, Mihatovic I, Golubovic V, Hegewald A, Becker J. Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs: part 1. Augmentation using bone graft substitutes and autogenous bone. Clin. Oral Impl. Res. 23, 2012; 83-89. doi: 10.1111/j.1600-0501.2011.02187.x [ABSTRACT FROM AUTHOR]