Prospective Clinical Multicenter Study Evaluating the 5-Year Performance of Zirconia Implants in Single-Tooth Gaps.

PURPOSE: In recent years, ceramic implants made of zirconia have secured a niche position next to established titanium implants, due partly to new scientific findings and positive clinical experience with the handling of ceramic implants. The aim of this study was to assess the clinical and radiographic data for monotype ceramic implants that have remained in place for 60 months under masticatory loading. MATERIALS AND METHODS: In 2011, this prospective clinical study included patients with a single-tooth gap in the maxilla and mandible. Monotype ceramic implants (Straumann) were used according to a standard protocol. Provisional prostheses were placed after 3 months, followed by final prostheses 3 months later. Patients were invited for a 60-month follow-up. Implant survival was analyzed from lifetime data. Success rates and crestal bone levels were evaluated from implant placement to 6, 12, 36, and 60 months after surgery. RESULTS: From the initial 44 patients recruited, 36 were analyzable for the 60-month follow-up. With one implant lost before the 6-month followup, the survival rate after 60 months was 97.7%, and the mean survival time was 58.7 months. Sixty months after implant placement, the success rate was 97.2% (95% confidence interval = 84.6% to > 99.9%). Mean bone loss after 60 months was 0.99 (± 0.59) mm. CONCLUSION: After 60 months, monotype ceramic implants made of zirconia achieved success and survival rates comparable with those reported for titanium implants in selected patient populations. Ceramic implants can be used as an alternative to titanium implants at the request of patients and if specifically indicated, for example, due to titanium intolerance.

A prospective clinical study to evaluate the performance of zirconium dioxide dental implants in single-tooth edentulous area: 3-year follow-up.

BACKGROUND: Traditionally, dental implants have been made from titanium or titanium alloys. Alternatively, zirconia-based ceramic implants have been developed with similar characteristics of functional strength and osseointegration. Ceramic implants offer advantages in certain settings, e.g. in patients who object to metal dental implants. The aim of this study was to investigate the mid-term (36 months) clinical performance of a ceramic monotype implant in single-tooth edentulous area. METHODS: This was a prospective, open-label, single-arm study in patients requiring implant rehabilitation in single-tooth edentulous area. Ceramic implants (PURE Ceramic Implant, Institut Straumann AG, Basel, Switzerland) with a diameter of 4.1 mm were placed following standard procedure and loaded with provisional and final prostheses after 3 and 6 months, respectively. Implant survival rate and implant success rate were evaluated and crestal bone levels were measured by analysing standardized radiographs during implant surgery and at 6, 12, 24 and 36 months. RESULTS: Forty-four patients received a study implant, of whom one patient withdrew consent after 3 months. With one implant lost during the first 6 months after surgery, the implant survival rate was 97.7% at 6 months. No further implants were lost over the following 30 months, and 3 patients were lost to follow-up during this time frame. This led to a survival rate of 97.5% at 36 months. Six months after implant surgery 93.0% of the implants were considered "successful", increasing to 97.6% at 12 months and remaining at this level at 24 months (95.1%) and 36 months (97.5%). Bone loss was most pronounced in the first half-year after implant surgery (0.88 ± 0.86 mm). By contrast, between 12 and 36 months the mean bone level remained stable (minimal gain of 0.06 [± 0.60] mm). Hence, the overall bone loss from implant surgery to 36 months was 0.97 (± 0.88) mm. CONCLUSIONS: In the follow-up period ceramic implants can achieve favourable clinical outcomes on a par with titanium implants. For instance, these implants can be recommended for patients who object to metal dental implants. However, longer term studies with different edentulous morphology need to confirm the present data. TRIAL REGISTRATION: Registered on www.clinicaltrials.gov : NCT02163395 .

Perioperative Bromelain Therapy after Wisdom Teeth Extraction - A Randomized, Placebo-Controlled, Double-Blinded, Three-Armed, Cross-Over Dose-Finding Study.

Reduction in postoperative edema and inflammatory reactions is the key to the posttraumatic regeneration process. Use of bromelain is well established in this indication, but there is some controversy with regard to the optimal dosing of this drug. The aim of our study was therefore to investigate the efficacy of dosage-dependent therapy with bromelain in patients after wisdom teeth extraction by comparing the registered dosage 1000 FIP (Fédération Internationale Pharmaceutique) against higher dosages of 3000 FIP and 4500 FIP. A total of 75 patients were randomized to one of the three dosage arms, and 68 of these patients were finally analyzed in the modified intention-to-treat population. Patients involved underwent two surgery sessions: one study period being conducted under treatment with bromelain and the other with placebo. Postoperative swelling determined by a 3D face scanning system was defined as the primary endpoint; further efficacy parameters were maximum swelling, pain, difficulty in swallowing, and use of analgesics. A superiority of treatment with 3000 FIP and 4500 FIP versus 1000 FIP could not be demonstrated. The analysis of pooled bromelain treatments versus placebo did, however, show a clear trend in favor of bromelain for all assessments. Adverse events did not occur more frequently under bromelain therapy compared with placebo. This study thus clearly supports the clinical relevance of treatment of postoperative conditions with bromelain, and the recommended daily dose was sufficiently effective in this trial and indication. Copyright © 2016 John Wiley & Sons, Ltd.

A prospective clinical study to evaluate the performance of zirconium dioxide dental implants in single-tooth gaps.

INTRODUCTION: Dental implants have traditionally been made from titanium or its alloys, but recently full-ceramic implants have been developed with comparable osseointegration properties and functional strength properties to titanium. These ceramic implants may have advantages in certain patients and situations, for example, where esthetic outcomes are particularly important. OBJECTIVE: The objective of this investigation was to evaluate the performance of a newly developed full-ceramic ZrO2 monotype implant design (PURE Ceramic Implant; Institut Straumann AG, Basel, Switzerland) in single-tooth gaps in the maxilla and mandible. MATERIAL AND METHODS: This was a prospective, open-label, single-arm study in patients requiring implant rehabilitation in single-tooth gaps. Full-ceramic implants were placed, with provisional and final prostheses inserted after 3 and 6 months, respectively. Crestal bone level was measured at implant placement and after 6 and 12 months. Implant survival and success were evaluated after 6 and 12 months. Further evaluations are planned after 24 and 36 months. RESULTS: Forty-six patients were screened for potential study participation, of whom 44 (17 men and 27 women, mean age 48 ± 14 years) were recruited into the study. The majority of implants (90.9%) were placed in the maxilla. The implant survival and implant success rate after 12 months were 97.6%. A minor change of the mean bone level occurred between implant loading (final prosthesis insertion after 6 months) and 12 months (-0.14 mm) after initial bone remodeling was observed between implant placement and loading (-0.88 mm). CONCLUSIONS: The results indicated that monotype ceramic implants can achieve clinical outcomes comparable to published outcomes of equivalent titanium implants.

Histological evaluation of different abutments in the posterior maxilla and mandible: an experimental study in humans.

OBJECTIVES: To histologically evaluate and compare the performance of healing abutments with either hydrophobic or hydrophilic surface properties in humans. MATERIALS AND METHODS: According to a parallel-group design, titanium implants placed in the posterior mandible and maxilla of 30 patients were randomly assigned to either (1) hydrophobic machined (M), (2) chemically modified hydrophilic (mod) acid etched (MA) titanium (Ti) (modMA1) or (3) modMA Ti- Zirconium alloy (modMA2) healing abutments and left to heal in a transmucosal position. At 8 weeks, the abutments and a limited soft tissue biopsy were harvested according to a standardized procedure and processed for histological analysis (primary outcomes: percentage epithelial- (EC) and subepithelial connective tissue contact (CTC) to the abutment surface). RESULTS: The surgical procedure was associated with an incomplete mucosal coverage of the study abutments in nine patients, and an unintentional submerged healing procedure in three patients. Per protocol analysis (18 patients) has pointed to an improved quantitative EC [modMA2 (53.45 ± 28.25) > modMA1 (32.25 ± 24.3) > M (23.15 ± 16.09)] and CTC [modMA2 (75.12 ± 43.22) > modMA1 (69.41 ± 46.74) > M (47.63 ± 19.28)] (%) to modMA surfaced abutments. CONCLUSIONS: It was concluded that modMA surfaces may have the potential to enhance soft tissue adhesion at the transmucosal aspect of titanium dental implants.

Containment and contouring (CoCoon) technique: a biologically adequate approach to less invasive autogenous preimplant augmentation of bone.

We have analysed retrospectively whether the less invasive zygomatic buttress graft is able to meet the dimensional and biological requirements of preimplant augmentation of bone. A total of 273 patients were treated by zygomatic buttress graft, of whom 42 (12 men and 30 women) met the criteria for inclusion. Intensity of pain was judged by a visual analogue score (VAS). Complications of grafting were evaluated, and dental implants were studied on clinical and radiographic examinations. The Schneiderian membrane was perforated in 13 cases (28%). The mean (SD) postoperative VAS was 3.1 (0.9) at the donor site. The mean (SD) follow-up after implant was 17(8) months. Two grafts were lost, one from initial dehiscence and later infection, and the other from infection. The mean (SD) marginal resorption of bone graft was 0.5 (0.7) mm. No implant was lost during the observation period. The zygomatic buttress graft meets the biological and dimensional requirements of augmentation of bone before implant that allows the dental implants to survive with satisfactory prosthetic rehabilitation.

Dentin as a suitable bone substitute comparable to ß-TCP--an experimental study in mice.

Microvascular supply is of fundamental importance to the survival and integration of grafting. Since the autogenous bone is still the gold standard for osseous augmentation, the aim of this study was to analyze the initial osseous, angiogenic and inflammatory response and subsequent osseointegration after implantation of dentin and beta-tricalcium phosphate (ß-TCP) scaffolds into the calvaria chamber of balb/c mice comparing with bone. The vascularisation of perforated implants of dentin (n=8), ß-TCP (n=8) and isogenic calvarial bone (n=8) displaying pores similar in size and structure was analyzed in vivo using intravital fluorescence microscopy. In additional animals (n=24) the osseointegration of dentin, ß-TCP and bone implants was assessed by fluorochrome sequential labelling of growing bone for up to 12 weeks. Animals without implants served as controls. Intravital fluorescence microscopy revealed that implantation of bone substitutes caused an only mild inflammatory response. Comparable to isogenic bone both dentin and ß-TCP scaffolds were found nearly completely vascularized by day 22 and osseointegrated within 12 weeks. In conclusion, dentin and ß-TCP scaffolds are similar to isogenic bone in terms of inflammatory and neovascularization response, highlighting their potential utility in regeneration of bone defects.

Biomechanical evaluation of a microstructured zirconia implant by a removal torque comparison with a standard Ti-SLA implant.

OBJECTIVES: The purpose of this study was to evaluate the biomechanical bone tissue response to novel microstructured zirconia implants in comparison to sandblasted and acid-etched (SLA) titanium implants through the analysis of removal torque (RTQ) measurements. MATERIALS AND METHODS: Ti-SLA implants with a sandblasted, large-grit and acid-etched surface were compared with zirconia implants with an acid-etched surface. All implants had the same shape, a diameter of 4.1 mm and a length of 10 mm. A total of 136 implants were placed in the maxillae of 17 miniature pigs. Six animals were sacrificed after both 4 and 8 weeks and five animals were sacrificed after 12 weeks, thus providing a total of 102 implants for RTQ testing (34 implants were reserved for future histological analysis). The RTQ analysis was successfully performed, using a mixed model regression with P-values calculated using the nonparametric Brunner-Langer method, on 100 of the 102 implants, two were excluded from the analysis. RESULTS: The adjusted mean RTQ values for Ti-SLA implants were 131 Ncm (95% CI: 107-155) at 4 weeks, 128 Ncm (108-148) Ncm at 8 weeks, and 180 Ncm (153-207 Ncm) at 12 weeks of healing, whereas RTQ values for the zirconia implants were 110 Ncm (86-134), 97 Ncm (76-118) and 147 Ncm (121-174) at the corresponding time intervals. A comparison of the implant materials resulted in P-values of P = 0.114 at 4 weeks, P = 0.034 at 8 weeks and P = 0.105 at 12 weeks (significance set at P < 0.05). CONCLUSIONS: Within the limits of the present study, it could be confirmed that the biomechanical bone-tissue response of the investigated zirconia implants is non-inferior to that of the well-documented, roughened titanium surface, at each time point, within the set tolerance. There were no statistically significant differences between the two materials after a healing period of 4 and 12 weeks. The RTQ values of both implant types increased significantly from the 8-week to the 12-week time point.

Calvaria bone chamber--a new model for intravital assessment of osseous angiogenesis.

The faith of tissue engineered bone replacing constructs depends on their early supply with oxygen and nutrients, and thus on a rapid vascularization. Although some models for direct observation of angiogenesis are described, none of them allows the observation of new vessel formation in desmal bone. Therefore, we developed a new chamber model suitable for quantitative in vivo assessment of the vascularization of bone substitutes by intravital fluorescence microscopy. In the parietal calvaria of 32 balb/c mice a critical size defect was set. Porous 3D-poly(L-lactide-co-glycolide) (PLGA)-blocks were inserted into 16 osseous defects (groups 3 and 4) while other 16 osseous defects remained unequipped (groups 1 and 2). By placing a polyethylene membrane onto the dura mater, the angiogenesis was mainly restricted to the osseous margins (groups 2 and 4). Microvascular density, angiogenesis, and microcirculatory parameters were evaluated repetitively during 22 days. In all animals, only a mild inflammatory reaction was observed with a climax after 2 weeks. The implantation of PLGA scaffolds resulted in a vascular growth directed towards the center of the defect as demonstrated by the significantly (p < 0.05) enhanced central microvascular densitiy from day 3 to day 22 when compared with unequipped chambers. The additional application of polyethylene membrane was found to reduce significantly the microvessel density mainly in the center of both scaffolds and defects. The present calvaria bone chamber allows for the first time to assess quantitatively the angiogenesis arising from desmal bone directly in vivo. Therefore, this chronic model may support the future research in the biological adequacy of bone substitutes.

Comparably accelerated vascularization by preincorporation of aortic fragments and mesenchymal stem cells in implanted tissue engineering constructs.

The demanding need for tissue replacement resulted in manifold approaches for the construction of different tissues. One common problem which hampers the clinical usage of tissue engineering constructs is a limited vascularization. In an attempt to accelerate the vascularization of tissue engineering constructs we compared the usage of bone marrow mesenchymal stem cells (bmMSCs) and fragments derived from the aorta in vivo. Tissue engineering constructs composed of PLGA scaffolds containing Matrigel (n = 8), aortic fragments embedded in Matrigel (n = 8), bmMSCs embedded in Matrigel (n = 8), and aortic fragments embedded in Matrigel combined with bmMSCs (n = 8) were implanted into dorsal skinfold chambers of balb/c mice and analyzed repetitively over 14 days. In all groups a weak inflammatory response was transiently apparent. Vascularization was significantly (p = 0.05) accelerated in bmMSC and aortic fragments containing constructs compared with Matrigel alone, demonstrated by a distinctly increased microvascular density throughout the whole experiment. The combination of bmMSCs and aortic fragments showed no additional effect compared with bmMSCs and aortic fragments alone. The accelerated vascularization and microvascular density of tissue engineering constructs triggered by bmMSCs and aortic fragments is comparable. Thus aortic fragments provide a new promising source for clinical relevant tissue engineering constructs.

Prolongated survival of osteoblast-like cells on biodegradable scaffolds by heat shock preconditioning.

The implantation of tissue-engineered constructs leads to hypoxic and physical stress to the seeded cells until they were reached by a functional microvascular system. Preconditioning of cells with heat shock induced heat shock proteins, which can support the cells to survive a subsequent episode of stress that would otherwise be lethal. Preconditioning of tissue-engineered constructs resulted in significantly higher number of surviving osteoblast-like cells (OLC). At the 6th and 10th day, angiogenic response was found comparative to poly(L-lactide-co-glycolide) (PLGA) scaffolds vitalized with either unconditioned or preconditioned OLC. However, they were significantly enhanced compared with the nonvitalized collagen-labeled PLGA scaffolds. This study demonstrates that vitalization of PLGA scaffolds with OLC accelerates the angiogenic response induced by the surrounding host tissue. In addition, heat shock preconditioning significantly enhances the survival rate of the OLC that are seeded on these scaffolds. Thus, vitalization of substitutes with adequately pretreated OLC may promise biologically adequate osseous restorations.

Forty sandwich osteotomies in atrophic mandibles: a retrospective study.

PURPOSE: The aim of the present retrospective study was to assess the suitability of segmental mandibular sandwich osteotomy combined with an interpositional autograft to meet the dimensional requirements of preimplant bone augmentation in cases of a severely atrophic mandible. PATIENTS AND METHODS: A total of 27 consecutive patients (6 men and 21 women) were included in the present study. The amount of bone gain was calculated using digital volume tomography before surgery and 3 months after bone augmentation. RESULTS: The postoperative course was uneventful for 18 patients. Temporary sensory disturbances were observed in 6 patients, with complete recovery after 3 to 12 weeks. Dehiscence of soft tissue closure occurred in 3 patients. The mean vertical gain was 3.41 mm (range 0.3 to 12). The mean horizontal gain was 3.08 mm (range 0.2 to 8.5). A total of 88 implants were placed in 40 surgical sites at 12 weeks after bone reconstruction. CONCLUSION: Segmental mandibular sandwich osteotomy is a suitable augmentation procedure in the mandible for the atrophic alveolar ridge and provides adequate height and transversal bone augmentation.

In vitro biomechanical comparison of the effect of pattern, inclination, and size of positional screws on load resistance for bilateral sagittal split osteotomy.

PURPOSE: The purpose of this in vitro investigation was to determine whether the pattern, angle of placement, or size of positional screws affected their ability to resist vertical loads resembling mastication in the bilateral sagittal split osteotomy system. MATERIALS AND METHODS: Standardized bone substitutes were secured with three 12- to 16 mm-long, 1.85-, 2.0-, 2.1-, and 2.4-mm outer diameter, self-tapping titanium screws (Synthes, Solothurn, Switzerland) in various patterns using a positional screw technique. These patterns included transbuccal triangular, intraoral triangular, and transbuccal linear patterns. The models were secured in a jig and subjected to vertical loads by a mechanical testing unit (1475 UPM; Zwick, Ulm, Germany) until failure. Loading test data analysis was based on peak load values resulting in mechanical deformation of the system (1-, 3-, and 5-mm displacement), maximal force, and stiffness (load/displacement slope curve) for each group. Means and standard deviations were derived and compared for statistical significance using univariate analysis of variance with a confidence level of 95% (P values < .05). RESULTS: The designed study demonstrated that 1.85- and 2.0-mm-diameter positional screws provided similar stability in all 3 setups. Three screws placed in an inverted L pattern at 90° (simulating a transbuccal approach) showed significantly higher resistance to vertical forces for advancement movements at 1-, 3-, and 5-mm displacement when compared with the inverted L group of screws placed at an angle (intraoral approach) or 3 screws in a linear pattern placed at 90° (transbuccal approach) (P < .01). CONCLUSIONS: Under the conditions tested in this in vitro study, differences in the load resistance of positional screws placed in a transbuccal or intraoral approach could be demonstrated depending on the fixation technique. The transbuccal group of 3 screws in an inverted L pattern showed significantly greater stability than the intraoral group of 3 screws placed in an inverted L pattern and the transbuccal group of 3 screws in a linear pattern. Resistance to vertical loads with 1.85-mm screws was similar to that with the standard 2.0-mm screws in all 3 setups. The results of this study suggest that the angle of screw placement (surgical approach) and pattern have a greater influence on the stability of the bilateral sagittal split osteotomy system than the screw size.

Introduction of e-learning in dental radiology reveals significantly improved results in final examination.

PURPOSE: Because a traditionally instructed dental radiology lecture course is very time-consuming and labour-intensive, online courseware, including an interactive-learning module, was implemented to support the lectures. The purpose of this study was to evaluate the perceptions of students who have worked with web-based courseware as well as the effect on their results in final examinations. MATERIALS AND METHODS: Users (n(3+4)=138) had access to the e-program from any networked computer at any time. Two groups (n(3)=71, n(4)=67) had to pass a final exam after using the e-course. Results were compared with two groups (n(1)=42, n(2)=48) who had studied the same content by attending traditional lectures. In addition a survey of the students was statistically evaluated. RESULTS: Most of the respondents reported a positive attitude towards e-learning and would have appreciated more access to computer-assisted instruction. Two years after initiating the e-course the failure rate in the final examination dropped significantly, from 40% to less than 2%. CONCLUSIONS: The very positive response to the e-program and improved test scores demonstrated the effectiveness of our e-course as a learning aid. Interactive modules in step with clinical practice provided learning that is not achieved by traditional teaching methods alone. To what extent staff savings are possible is part of a further study.

Microvascular response to the subperiosteal implantation of self-inflating hydrogel expanders.

PURPOSE: Excessive stretching of the overlying soft tissue often occurs during the attempt at primary closure after bone augmentation. Preliminary soft tissue expansion may prevent such perfusion disturbances caused by stretching. The purpose of this study was to investigate the effects of using self-inflating expanders at different rates to expand overlying soft tissue prior to the bone grafting procedure. MATERIALS AND METHODS: Two different hydrogel expanders with different inflation curves were used. For the experiments, 48 Lewis rats were divided into six groups of eight animals each. In four groups, the different expanders were implanted subperiosteally on the calvarium. In two of these groups, an observation window was implanted for intravital microscopy. In the other two groups, histologic analysis of the covering skin was performed. Intravital microscopy of the unexpanded periosteum and histologic analyses of unoperated rats served as control groups. RESULTS: Following implantation of the expanders, intravital microscopic examinations showed that, irrespective of the expansion curve, periosteal microcirculation had stopped completely without reperfusion within 14 days. Histologic analyses of the soft tissues, however, showed a well-vascularized connective tissue layer clinging to the expander. The microvessel density measured was significantly higher above slowly inflating expanders (91.2 ± 8.8 vessels/mm²) than above rapidly inflating expanders (48.4 ± 2.7 vessels/mm²) or unoperated periosteum (60.4 ± 4.8 vessels/mm²). CONCLUSIONS: Subperiosteal implantation of self-inflating expanders leads to complete ischemia of the periosteum. However, replacement of the periosteum by connective tissue takes place within 14 days; as a result of subcutaneous angiogenesis, this tissue may have a significantly higher microvessel density than healthy periosteum.

Effects of VEGF loading on scaffold-confined vascularization.

Adequate vascularization of tissue-engineered constructs remains a major challenge in bone grafting. In view of this, we loaded ß-tricalcium-phosphate (ß-TCP) and porous poly(L-lactide-co-glycolide) (PLGA) scaffolds via collagen coating with vascular endothelial growth factor (VEGF) and studied whether the VEGF loading improves scaffold angiogenesis and vascularization. Dorsal skinfold chambers were implanted into 48 balb/c mice, which were assigned to 6 groups (n = 8 each). Uncoated (controls), collagen-coated, and additionally VEGF-loaded PLGA and ß-TCP scaffolds were inserted into the chambers. Angiogenesis, neovascularization, and leukocyte-endothelial cell interaction were analyzed repeatedly during a 14-day observation period using intravital fluorescence microscopy. Furthermore, VEGF release from PLGA und ß-TCP scaffolds was studied by ELISA. Micromorphology was studied from histological specimens. Unloaded ß-TCP scaffolds showed an accelerated and increased angiogenic response when compared with unloaded PLGA scaffolds. In vitro, PLGA released significantly higher amounts of VEGF compared with ß-TCP at the first two days resulting in a rapid drop of the released amount at the following days up to day 7 where the VEGF release was negligible. Nonetheless, in vivo VEGF loading increased neovascularization, especially in ß-TCP scaffolds. This increased vascularization was associated with a temporary leukocytic response with pronounced leukocyte-endothelial cell interaction at days 3 and 6. Histology revealed adequate host tissue response and engraftment of both ß-TCP and PLGA scaffolds. Our study demonstrates that ß-TCP scaffolds offer more suitable conditions for vascularization than PLGA scaffolds, in particular if they are loaded with VEGF.

IL-1 polymorphism and periimplantitis. A literature review.

The most important factor leading to periimplantitis with bone loss appears to be an inflammatory process due to plaque accumulation. The object of this article was to present a review of the literature on a possible correlation between IL-1 polymorphism and periimplantitis. Research was carried out in the PUBMED and WEB OF KNOWLEDGE literature databases and 27 relevant articles were found. Of these articles, 4 groups of authors came to the conclusion that no correlation exists between IL-1 polymorphism and periimplantitis. In 5 articles by 4 groups of authors, the influence of IL-1 polymorphism on periimplantitis is unclear. 9 studies prove a correlation between IL-1 polymorphism and periimplantitis, and 6 studies also document a direct linkage between gene polymorphism and periimplantitis, if certain cofactors are present. IL-1 polymorphism is frequently connected with "noninfectious periimplant bone loss". Other studies prove that the inflammatory mediators and IL-1beta were significantly elevated in the gingival crevicular fluid (GCF) of infected implants. Many studies document that IL-1 polymorphism alone cannot be considered a risk factor for bone loss, but in combination with smoking, it is closely associated with periimplant bone loss. More studies are needed to discover possible correlations between IL-1 polymorphism and periimplantitis.

Bone augmentation after soft-tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration.

OBJECTIVES: The success of bone augmentation, for example of the alveolar ridge, might be endangered by dehiscence of the soft tissue that covers the augmented bone. Soft-tissue coverage can be achieved without tension through pre-augmentation tissue expansion with hydrogel expanders. We used a periosteal chamber to study the influence of tissue expansion on microcirculation and osseointegration in an in vivo animal model. MATERIAL AND METHODS: Sixteen isogeneic Lewis rats were randomised into two groups. Additional eight animals served as donors of isogeneic bone grafts (Group 3, n=8). The bone grafts were harvested and implanted into Group 1 animals (n=8) (without tissue expansion) and Group 2 animals (after tissue expansion). In Group 2 (n=8), hydrogel expanders were inserted subperiosteally at the site to be augmented for 21 days. We used intravital microscopy to monitor microcirculation in vivo for 19 days after implantation. Specimens from both groups were evaluated histologically. RESULTS: During the entire study period, functional microvessel density in the region above the augmentation material was significantly higher after previous tissue expansion (P>0.05). Both groups showed physiological microcirculation around the augmentation material. Histology revealed bone osseointegration of the bone graft in the group with tissue expansion and the presence of connective and granulation tissue in the group without tissue expansion. CONCLUSIONS: Pre-augmentation soft-tissue expansion with hydrogel expanders leads to higher functional microvessel density in the tissue above the augmentation material and thus, to more rapid osseointegration. The use of hydrogel expanders appears to increase the probability of success, especially of pre-implant bone augmentation.

Bone repair by cell-seeded 3D-bioplotted composite scaffolds made of collagen treated tricalciumphosphate or tricalciumphosphate-chitosan-collagen hydrogel or PLGA in ovine critical-sized calvarial defects.

The aim of this study was to investigate the osteogenic effect of three different cell-seeded 3D-bioplotted scaffolds in a ovine calvarial critical-size defect model. The choice of scaffold-materials was based on their applicability for 3D-bioplotting and respective possibility to produce tailor-made scaffolds for the use in cranio-facial surgery for the replacement of complex shaped boneparts. Scaffold raw-materials are known to be osteoinductive when being cell-seeded [poly(L-lactide-co-glycolide) (PLGA)] or having components with osteoinductive properties as tricalciumphosphate (TCP) or collagen (Col) or chitosan. The scaffold-materials PLGA, TCP/Col, and HYDR (TCP/Col/chitosan) were cell-seeded with osteoblast-like cells whether gained from bone (OLB) or from periost (OLP). In a prospective and randomized design nine sheep underwent osteotomy to create four critical-sized calvarial defects. Three animals each were assigned to the HYDR-, the TCP/Col-, or the PLGA-group. In each animal, one defect was treated with a cell-free, an OLB- or OLP-seeded group-specific scaffold, respectively. The fourth defect remained untreated as control (UD). Fourteen weeks later, animals were euthanized for histo-morphometrical analysis of the defect healing. OLB- and OLP-seeded HYDR and OLB-seeded TCP/Col scaffolds significantly increased the amount of newly formed bone (NFB) at the defect bottom and OLP-seeded HYDR also within the scaffold area, whereas PLGA-scaffolds showed lower rates. The relative density of NFB was markedly higher in the HYDR/OLB group compared to the corresponding PLGA group. TCP/Col had good stiffness to prepare complex structures by bioplotting but HYDR and PLGA were very soft. HYDR showed appropriate biodegradation, TCP/Col and PLGA seemed to be nearly undegraded after 14 weeks. 3D-bioplotted, cell-seeded HYDR and TCP/Col scaffolds increased the amount of NFB within ovine critical-size calvarial defects, but stiffness, respectively, biodegradation of materials is not appropriate for the application in cranio-facial surgery and have to be improved further by modifications of the manufacturing process or their material composition.

Accelerated angiogenic host tissue response to poly(L-lactide-co-glycolide) scaffolds by vitalization with osteoblast-like cells.

BACKGROUND: Bone substitutes should ideally promote rapid vascularization, which could be accelerated if these substitutes were vitalized by autologous cells. Although adequate engraftment of porous poly(L-lactide-co-glycolide) (PLGA) scaffolds has been demonstrated in the past, it has not yet been investigated how vascularization is influenced by vitalization or, more precisely, by seeding PLGA scaffolds with osteoblast-like cells (OLCs). For this reason, we conducted an in vivo study to assess host angiogenic and inflammatory responses after the implantation of PLGA scaffolds vitalized with isogeneic OLCs. MATERIALS AND METHODS: OLCs were seeded on collagen-coated PLGA scaffolds that were implanted into dorsal skinfold chambers in BALB/c mice (n = 8). Two further groups of animals received either collagen-coated (n = 8) or uncoated PLGA scaffolds (n = 8). Animals that received chambers without implants served as controls (n = 8). Angiogenesis, neovascularization, and leukocyte-endothelial cell interaction were analyzed for 14 days using intravital fluorescence microscopy. RESULTS: PLGA scaffolds with and without OLCs showed a temporary increase in leukocyte recruitment. At day 3 after implantation, a marked angiogenic host tissue response was observed in close vicinity of all scaffolds studied. At days 6 and 10, the angiogenic response was significantly higher (p < 0.05) in PLGA scaffolds vitalized with OLCs than in uncoated or collagen-coated PLGA scaffolds. The majority of OLCs, however, died within 14 days after implantation. CONCLUSION: Our study demonstrates that PLGA scaffold vitalization with OLCs accelerates the angiogenic response in the surrounding host tissue. Bone substitutes created by tissue engineering may thus be superior to nonvitalized substitutes although the seeded cells do not survive for long periods.