Biomaterial shell bending with 3D-printed templates in vertical and alveolar ridge augmentation: a technical note.

OBJECTIVES: Alveolar ridge and vertical augmentations are challenging procedures in dental implantology. Even material blocks with an interconnecting porous system are never completely resorbed. Shell techniques combined with autologous bone chips are therefore the gold standard. Using biopolymers for these techniques is well documented. We applied three-dimensional (3-D) techniques to create an individualized bending model for the adjustment of a plane biopolymer membrane made of polylactide. STUDY DESIGN: Two cases with a vertical alveolar ridge defect in the maxilla were chosen. The cone beam computed tomography data were processed with a 3-D slicer and the Autodesk Meshmixer to generate data about the desired augmentation result. STL data were used to print a bending model. A 0.2-mm poly-D, L-lactic acid membrane (KLS Matin Inc., Tuttlingen, Germany) was bended accordingly and placed into the defect via a tunnel approach in both cases. A mesh graft of autologous bone chips and hydroxylapatite material was augmented beneath the shell, which was fixed with osteosynthesis screws. RESULTS: The operative procedure was fast and without peri- or postoperative complications or complaints. The panoramic x-ray showed correct fitting of the material in the location. Bone quality at the time of implant placement was type II, resulting in good primary stability. CONCLUSIONS: A custom-made 3-D model for bending confectioned biomaterial pieces is an appropriate method for individualized adjustment in shell techniques. The advantages over direct printing of the biomaterial shell and products on the market, such as the Xyoss shell (Reoss Inc., Germany), include cost-efficiency and avoidance of regulatory issues.

Complications with allogeneic, cancellous bone blocks in vertical alveolar ridge augmentation: prospective clinical case study and review of the literature.

OBJECTIVES: Vertical bone augmentation in dental implantology is an indication for cancellous allogeneic bone blocks (ABB). However, these materials may lead to adverse reactions, which are known well in orthopedics but rarely published. Therefore, in this study, we performed an evaluation of the use of ABB in vertical bone augmentation in clinical dental implantology. STUDY DESIGN: The prospective clinical study included 20 cases with vertical augmentation using ABB and subsequent or simultaneous placement of implants in the lateral maxilla and mandible. Follow-up included panoramic radiography, tissue healing, and peri-implantitis. Because of the limited number of patients, the report was planned to be descriptive only. Loss of ABB or peri-implantitis of more than 30% of the intraosseous implant length was deemed to indicate failure. RESULTS: The study was cancelled after six cases because of an unexpectedly high number of complications (5 of 6; 83%). The average surveillance time was 1460 days. Three types of unsatisfying outcome were observed: type I, early complete loss of the augmentation with soft tissue defects after 3 to 8 weeks (n = 2); type II, early soft tissue maceration (up to 8 weeks) without loss of coverage and complete early bone healing with later peri-implantitis and bone loss after prosthetic loading (6 months or later; n = 2); and type III, complication-free bone healing with subsequent peri-implantitis after prosthetic loading (6 months or later; n = 1). CONCLUSIONS: Complications were observed in vertical augmentation with ABB and implant placement. After careful consideration, literature data were found to support these results and also suggest that tissue level implants may be advantageous in vertical bone augmentation with ABB.

Surgical evaluation of panoramic radiography and cone beam computed tomography for therapy planning of bisphosphonate-related osteonecrosis of the jaws.

OBJECTIVES: The purpose of this retrospective study was to compare the clinical significance of panoramic radiography (orthopantomography [OPTG]) and cone beam computed tomography (CBCT) for therapy planning of bisphosphonate-related osteonecrosis of the jaw (BRONJ) by surgeons. STUDY DESIGN: Using standardized questionnaire, eight maxillofacial surgeons evaluated intraoral photographs of the clinical situation of 14 patients with BRONJ as well as the corresponding radiographic images (OPTG, CBCT). The presence of five typical BRONJ signs (bone-remodeling, periosteal reaction, osteosclerosis, sequestra, and continuity of cortical bone) was evaluated with OPTG and CBCT. The influence of radiologic information on therapy decision was examined as well. RESULTS: On the basis of the information from intraoral photographs only, seven of the eight surgeons indicated that an additional radiographic examination was necessary for further therapy planning. For evaluation of the five radiographic BRONJ signs, CBCT provided significantly better values compared with OPTG (all P < .05). A before-and-after comparison showed that four of the eight surgeons changed their therapy concept after having three-dimensional CBCT information. The majority (6 of 8) of the surgeons considered that an additional CBCT was required for therapy planning, even after having studied the clinical photographs and OPTG images. CONCLUSION: These data demonstrate a significant advantage of CBCT over OPTG for surgeons with regard to therapeutic planning for BRONJ.

Bioactive and biodegradable silica biomaterial for bone regeneration.

Biosilica, a biocompatible, natural inorganic polymer that is formed by an enzymatic, silicatein-mediated reaction in siliceous sponges to build up their inorganic skeleton, has been shown to be morphogenetically active and to induce mineralization of human osteoblast-like cells (SaOS-2) in vitro. In the present study, we prepared beads (microspheres) by encapsulation of ß-tricalcium phosphate [ß-TCP], either alone (control) or supplemented with silica or silicatein, into the biodegradable copolymer poly(d,l-lactide-co-glycolide) [PLGA]. Under the conditions used, ≈5% ß-TCP, ≈9% silica, and 0.32µg/mg of silicatein were entrapped into the PLGA microspheres (diameter≈800µm). Determination of the biocompatibility of the ß-TCP microspheres, supplemented with silica or silicatein, revealed no toxicity in the MTT based cell viability assay using SaOS-2 cells. The adherence of SaOS-2 cells to the surface of silica-containing microspheres was higher than for microspheres, containing only ß-TCP. In addition, the silica-containing ß-TCP microspheres and even more pronounced, a 1:1 mixture of microspheres containing ß-TCP and silica, and ß-TCP and silicatein, were found to strongly enhance the mineral deposition by SaOS-2 cells. Using these microspheres, first animal experiments with silica/biosilica were performed in female, adult New Zealand White rabbits to study the effect of the inorganic polymer on bone regeneration in vivo. The microspheres were implanted into 5mm thick holes, drilled into the femur of the animals, applying a bilateral comparison study design (3 test groups with 4-8 animals each). The control implant on one of the two hind legs contained microspheres with only ß-TCP, while the test implant on the corresponding leg consisted either of microspheres containing ß-TCP and silica, or a 1:1 mixture of microspheres, supplemented with ß-TCP and silica, and ß-TCP and silicatein. The results revealed that tissue/bone sections of silica containing implants and implants, composed of a 1:1 mixture of silica-containing microspheres and silicatein-containing microspheres, show an enhanced regeneration of bone tissue around the microspheres, compared to the control implants containing only ß-TCP. The formation of new bone induced by the microspheres is also evident from measurements of the stiffness/reduced Young's modulus of the regenerated bone tissue. The reduced Young's modulus of the regenerating bone tissue around the implants was markedly higher for the silica-containing microspheres (1.1MPa), and even more for the 1:1 mixture of the silica- and silicatein-containing microspheres (1.4MPa), compared to the ß-TCP microsphere controls (0.4MPa). We propose that based on their morphogenetic activity on bone-forming cells in vitro and the results of the animal experiments presented here, silica/biosilica-based scaffolds are promising materials for bone repair/regeneration.

Laser-enhanced cytotoxicity of zoledronic acid and cisplatin on primary human fibroblasts and head and neck squamous cell carcinoma cell line UM-SCC-3.

INTRODUCTION: Low-level laser therapy (LLLT) is used in parodontitis treatment in combination with an antimicrobial photosensitizer. The purpose of this study was to investigate the combination of LLLT with cisplatin and zoledronic acid as potential photosensitizer in-vitro. MATERIALS AND METHODS: Primary human fibroblasts (PHF) and head and neck squamous cell carcinoma cells (HNSCC, exactly UM-SCC-3) were treated with different concentrations of zoledronatic acid and cisplatin and irradiated twice with a diode laser (wavelength 670 nm, 2 min). Cell viability was tested by XTT assay and histomorphological analysis with HE staining. RESULTS: LLLT increased bioviability for both cell lines (p < 0.001). LLLT lowered PHF viability at the highest concentrations of cisplatin (p = 0.027 and p = 0.005) and zoledronic acid (p < 0.001). For HNSCCs, LLLT reduced cell viability at every concentration of cisplatin (all p < 0.05). In cases of incubation with zoledronic acid, similar to fibroblasts, laser therapy lowered cell viability at the highest concentration only (p < 0.001). CONCLUSIONS: Within the limits of this study, it can be concluded that LLLT enhances the effect of cisplatin and zoledronic acid in the discussed cells in order to develop new therapeutic options for cysts in the cranio-maxillofacial region and other appropriate indications.

Modification of xenogenic bone substitute materials--effects on the early healing cascade in vitro.

INTRODUCTION: Initial platelet activation with subsequent cytokine release at the defect site plays a crucial role in tissue integration. The aim of this study was to evaluate the influence of topographic and biomimetic collagen modifications of a xenogenic bone substitute material (BSM) on in vitro platelet activation and cytokine release. MATERIAL AND METHODS: Three types of xenogenic BSM were used. Two BSM with different levels of granularity (large granule BSM [XBSM/L], small granule BSM [XBSM/S]) and a BSM with collagen (XBSM/C). All three samples were incubated with platelet concentrate of four healthy volunteers at room temperature for 15 min. For all groups, highly thrombogenic collagen type 1 served as a reference and an additional preparation with platelet concentrate only (without XBSM) served as control. Platelet count and cytokine release of VEGF, PDGF, TGF-ß, and IGF into the supernatant were measured. RESULTS: Compared with the control group, XBSM/C showed an increase in platelets consumption (mean 41,000 ± 26,000/ml vs. 471,000 ± 38,000/ml), cytokine release of VEGF (mean 46.8 ± 7.2 pg/ml vs. 18.8 ± 2.7 pg/ml), and PDGF (mean 18,350 ± 795 pg/ml vs. 2726 ± 410 pg/ml) but not IGF (194,728 ± 51,608 pg/ml vs. 1,333,911 ± 35,314 pg/ml). There was also an increase in cytokine release of TGF-ß in XBSM/C compared with XBSM/S (77,188 ± 27,413 pg/ml vs. 38,648 ± 13,191 pg/ml), but no such difference when compared with XBSM/L (77,188 ± 27,413 pg/ml vs. 53,309 ± 29,430 pg/ml). XBSM/L showed higher platelets consumption (301,000 ± 45,000 vs. 415,000 ± 98,000) and a higher cytokine release of PDGF (3511 ± 247 pg/ml vs. 3165 ± 78 pg/ml) compared with XBSM/S. There was no distinct difference in the levels of VEGF, TGF-ß, and IGF between XBSM/L and XBSM/S. CONCLUSIONS: Topographic as well as biomimetic modifications of the xenogenic BSM showed an increased platelet activation and cytokine release in vitro. This effect on the intrinsic healing cascade could result in comparable enhanced soft- and hard-tissue regeneration in vivo.

BMP-2 and bFGF release and in vitro effect on human osteoblasts after adsorption to bone grafts and biomaterials.

OBJECTIVES: Combination of scaffolds and growth factors is a promising option for several clinical problems in bone biomaterials. Simplified growth factor loading by adsorption from aqueous solution is one important option for this technology. We evaluated the adsorption followed by PBS rinsing, release and biological effect of transient loading with basic fibroblast growth factor (bFGF) and bone morphogenic protein 2 (BMP-2) on fresh frozen bone, processed bone matrix, collagen, and a ceramic material with immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and qRT-PCR. MATERIALS AND METHODS: The study consisted of three in vitro experiments (immunofluorescence, ELISA, and qRT-PCR) in human osteoblasts (HOB). The first evaluated the adsorption of the growth factors bFGF and BMP-2 to the biomaterials, analyzed by immunofluorescence assays. The second experiment used ELISA to analyze the release of the growth factors from the matrix. The biological effect of the growth factors on HOB was then studied with qRT-PCR experiments as the third step. RESULTS: Strongest sustained release peaks in ELISA were observed in bFGF loading on processed bone matrix (steam-resistant mineralized bone matrix, SMBM) with up to 553 pg/ml medium. BMP-2 loading was less effective in ELISA peak release experiments with up to 257 pg/ml medium in processed bone matrix (SMBM). bFGF showed also higher release peaks in collagen material (192 pg/ml) compared with BMP-2 (101 pg/ml). Cumulative release values 0-72 h were estimated. The expression of runX2, osteocalcin, and alkaline phosphatase as markers for osteoblast activity was correlating. CONCLUSION: The results showed sustained release of BMP-2 and bFGF after transient loading on bone biomaterials with a stronger effect in biological scaffolds. This is interesting for therapeutic growth factor loading as well as insights in natural growth factor matrix deposition during bone healing.

The original family revisited after 37 years: odontoma-dysphagia syndrome is most likely caused by a microduplication of chromosome 11q13.3, including the FGF3 and FGF4 genes.

OBJECTIVES: Fibroblast growth factors consist of receptor tyrosine kinase binding proteins involved in growth, differentiation, and regeneration of a variety of tissues of the head and neck. Their role in the development of teeth has been documented, and their presence in human odontogenic cysts and tumors has previously been investigated. Odontoma­dysphagia syndrome (OMIM 164330) is a very rare disorder characterized by clustering of teeth as compound odontoma, dysplasia and aplasia of teeth, slight craniofacial abnormalities, and dysphagia. We have followed the clinical course of the disease in a family over more than 30 years and have identified a genetic abnormality segregating with the disorder. MATERIALS AND METHODS: We evaluated clinical data from nine different family members and obtained venous blood probes for genetic studies from three family members (two affected and one unaffected). RESULTS: The present family with five patients in two generations has remained one out of only two known cases with this very rare syndrome. All those affected showed teeth dysplasia, oligodontia, and dysplasia and odontoma of the upper and lower jaw. Additional signs included dysphagia and strictures of the oesophagus. Comorbidity in one patient included aortic stenosis and coronary artery disease, requiring coronary bypasses and aortic valve replacement. Genome-wide SNP array analyses in three family members (two affected and one unaffected) revealed a microduplication of chromosome 11q13.3 spanning 355 kilobases (kb) and including two genes in full length, fibroblast growth factors 3 (FGF3) and 4 (FGF4). CONCLUSION: The microduplication identified in this family represents the most likely cause of the odontoma­dysphagia syndrome and implies that the syndrome is caused by a gain of function of the FGF3 and FGF4 genes. CLINICAL RELEVANCE: Mutations of FGF receptor genes can cause craniofacial syndromes such as odontoma­dysphagia syndrome. Following this train of thought, an evaluation of FGF gene family in sporadic odontoma could be worthwhile.

Early outcome of an implant system with a resorbable adhesive calcium-phosphate coating--a prospective clinical study in partially dentate patients.

This study aims to investigate the early outcome of a dental implant with bioactive calcium-phosphate (CaP) coating in the first year of usage in different clinical indications in partially edentulous patients, after early and delayed prosthetic loading. Therefore, in a prospective follow-up study, the cumulative survival and success rate of a conical, self-drilling and self-tapping implant system after 6 months and 1 year post-insertion was evaluated. A total of 311 CaP-coated implants were placed in 124 patients. Seventy-two implants in clinical high-quality bone situation were loaded after 2 weeks post-insertion with the definite restoration; the rest after 6 months. The indication for implant placement was treatment of partial dentate mandible and maxilla. One hundred sixty-three implants were placed in the posterior mandible, 117 in the posterior maxilla. In the frontal maxilla, 25 implants and in the frontal mandible, eight implants were used. In 126 cases (36%), bone augmentation procedures (guided bone regeneration and sinus lift) were performed concomitant with implant placement. The difference between primary and secondary stability (implant stability quotient (ISQ), Periotest, insertion torque), peri-implant clinical parameter as well as survival and success criteria were evaluated. In total, ISQ mean values after 6 months were higher than after implant placement. Periotest values increased in the period of the first 6 months and remained constant afterwards. After 6 months of insertion, the mean bone loss was 0.051 mm. After 12 months, a bone gain with a mean of +0.016 mm was observed; implants in the posterior maxilla showed significant less bone resorption than implants in the posterior mandible (p < 0.0001). In the most of the implants (74%), clinical normal gingival tissue could be observed. In 24%, a mild inflammation was analysed. In 35 implants, a provocation of peri-implant bleeding was possible. In the early loading group, no implant failure was seen. Altogether, one implant in D4 bone has been lost. The cumulative survival rate summed up to 99.7%. In general, implant success assessment analysis according to Albrektsson and Buser displayed success in 99.7% of the implants. With respect to the patient selection including 124 implants with minor and major augmentations as well as early loading prosthetic function, the 1-year clinical use of the studied implant system with CaP coating showed good results, comparable to that of conventional implants without a specific coating. After 1 year, neither special disadvantages nor benefits of CaP-coated implants could be evaluated. Long-term results are further needed.

Retrospective analysis of survival rates and marginal bone loss on short implants in the mandible.

OBJECTIVES: Short implants have become an interesting alternative to bone augmentation in dental implantology. Design of shorter implants and longer surveillance times are a current research issue. The goal of this study was to show the survival rates of short implants below 9 mm in the partly edentulous mandibular premolar and molar regions with fixed prosthetics. Marginal vertical and 2D bone loss was evaluated additionally. Different implant designs are orientationally evaluated. MATERIAL AND METHODS: A total of 247 dental implants with fixed prosthetics (crowns and bridges) in the premolar and molar region of the mandible were evaluated; 47 implants were 9 mm or shorter. Patient data were evaluated to acquire implant survival rates, implant diameter, gender and age. Panoramic X-rays were analysed for marginal bone loss. RESULTS: Average surveillance time was 1327 days. Cumulative survival rate (CSR) of short implants was 98% (1 implants lost) compared to 94% in the longer implants group without significance. Thirty-five of the short implants were Astratech (0 losses) and 12 were Camlog Screw Line Promote Plus (1 loss). Early vertical and two-dimensional marginal bone loss was not significantly different in short and regular length implant group with an average of 0.6 mm and 0.7 mm(2) in short implants over the observation period. CONCLUSIONS: Within the limitations of this study, we conclude that short implants with a length of 9 mm or less have equal survival rates compared with longer implants over the observation period of 1-3 years.

Vertical bone augmentation with simultaneous dental implantation using crestal biomaterial rings: a rabbit animal study.

BACKGROUND: Ceramic biomaterial blocks like hydroxyl apatite are too brittle for simple simultaneous vertical augmentation and dental implant placement. Biological scaffolds of xenogenic or allogenic origin are known to be advantageous. PURPOSE: The aim of this study was the proof of principle for combined vertical bone augmentation and dental implantation with marginal cuffs made of biological scaffolds with interconnecting porous system and titanium dental implants. MATERIALS AND METHODS: Cylindrical porcine biomaterial rings (processed, mineralized bone matrix) were placed in combination with titanium dental implants in the tibia model using six chinchilla bastard rabbits (n = 12 samples). Histological examination included undecalcified histological examination with toluidine blue staining and fluorescence microscopy. Animals were sacrificed after 30 days. RESULTS: The results showed bony healing in the scaffolds with immature bone tissue ingrowth following the trabecular structure, showing lamellar cancellous bone healing. Fluorescence microscope showed analogous results. CONCLUSION: The biological scaffold proved a biocompatibility in a xenogenic setting. The vertical bone augmentation with simultaneous implantation was successful and proved the feasibility of the concept.

Retrospective analysis of orbital floor fractures--complications, outcome, and review of literature.

This retrospective study aimed at investigating indications, surgical approaches, and the materials used for orbital floor reconstructions, as well as the clinical follow-up, particularly with regard to postoperative complications. This study comprised 189 patients who underwent surgery for fractures of the orbital floor between 2003 and 2007. Diagnosis and treatment were based on both physical examination and computed tomography scan of the orbit. Patients were retrospectively analyzed for data, such as mechanism of injury, classification of fracture, and complications. The most common cause of injury was physical assault followed by traffic accidents. Surgery was conducted with a mean delay of 2.9 days after the incident. Mid lower eyelid incision was the most common surgical approach to the orbital floor. For orbital floor reconstruction, polydioxanone sheets (70.5%) were mainly used, followed by Ethisorb Dura (23.3%) and titanium mesh (6.2%). There were 19.0% of patients who showed postoperative complications: 5.8% suffered from persisting motility impairment, 3.7% from enophthalmos, 3.2% from consistent diplopia, 2.6% from ectropion, and 0.5% from orbital infection. Intraorbital hematoma (3.2%) represented the most severe complications, one patient suffered lasting impairment of sight and another one, complete blindness of the affected eye. If postoperative impairment of vision becomes evident, immediate surgical intervention is mandatory. Retrobulbar hematoma is more likely to occur in heavily traumatized patients with comminuted fractures and also in patients taking anticoagulative medication. The subciliary approach to the orbit and repeated operations by the same approach are associated with a higher risk of developing ectropion.

Management of venous thrombosis in fibular free osseomusculocutaneous flaps used for mandibular reconstruction: clinical techniques and treatment considerations.

BACKGROUND: Mandibular reconstruction by means of fibula transplants is the standard therapy for severe bone loss after subtotal mandibulectomy. Venous failure still represents the most common complication in free flap surgery. We present the injection of heparine into the arterial pedicle as modification of the revising both anastomoses in these cases and illustrate the application with a clinical case example. METHODS: Methods consist of immediate revision surgery with clot removal, heparin perfusion by direct injection in the arterial vessel of the pedicle, subsequent high dose low-molecular weight heparin therapy, and leeches. After 6 hours postoperatively, images of early flap recovery show first sings of recovery by fading livid skin color. RESULTS: The application of this technique in a patient with venous thrombosis resulted in the complete recovery of the flap 60 hours postoperatively. Other cases achieved similar success without additional lysis Therapy or revision of the arterial anastomosis. CONCLUSION: Rescue of fibular flaps is possible even in patients with massive thrombosis if surgical revision is done quickly.

Two modifications in the treatment of keratocystic odontogenic tumors (KCOT) and the use of Carnoy's solution (CS)--a retrospective study lasting between 2 and 10 years.

This retrospective study aimed at evaluating the recurrence rates of keratocystic odontogenic tumors (KCOTs) that were enucleated with and without the application of Carnoy's solution (CS). The study included 36 KCOTs treated between 1996 and 2006. Recurrence rates were investigated in correlation with the respective treatment method applied. Additionally, any damage to the inferior alveolar nerve associated with treatment was analyzed. Treatments consisted of enucleation with (38.9%) or without (61.1%) the application of CS. Median follow-up was 4.5 years. Single enucleation showed a recurrence rate of 50%, but the additional application of CS reduced the recurrence rate to 14.3%. No detrimental effects of CS on the mandibular nerve were detected. Enucleation plus the application of CS reduced the recurrence rate of KCOTs compared with simple enucleation. The application of CS did not cause any damage to the mandibular nerve.

Fibrosarcoma of the childhood mandible.

A case of low-grade intraosseous fibrosarcoma of the mandible in a 9-year-old girl is described. The patient underwent pre-surgical chemotherapy which was abandoned as unsuccessful after two cycles. Radical tumour resection and mandibular reconstruction with a titanium bar were performed 3 months after diagnosis. No adjuvant therapy was given and lymph node dissection was not performed. No signs of recurrences or metastasis have been observed after a follow up time of 3 years so far. This article is presented to document the rarity of fibrosarcomas in the jaws of children and emphasizes the possible changes in the appearance of radiological imaging under tumour progression.

Imaging of bone transplants in the maxillofacial area by NewTom 9000 cone-beam computed tomography: a quality assessment.

OBJECTIVES: This study evaluates the definability and usability of bone transplant imaging with the NewTom 9000 cone-beam computed tomography (CBCT) device in a retrospective evaluation. METHODS: CBCT data of 21 patients were analyzed in 2 steps. Step 1: transplants of cancellous bone (n = 6) and transplants of cortico-cancellous bone (n = 15). Step 2: The second group was further divided into nonvasculated transplants (n = 8) and microvascular transplants (n = 7). NewTom 9000 CBCT data sets were reconstructed and converted into DICOM data (spatial resolution: 0.25 mm, axial slice thickness: 0.3 mm). The OsiriX program was used to establish cross-sections in all 3 dimensions. Image quality assessment of the cross-sections was performed by 4 dentists. RESULTS: CBCT scans of cortical bone transplants showed clear borders. All cancellous transplants were poorly defined and showed little x-ray contrast. In most cases these differences seen in the descriptive evaluation were not significant in the statistical analysis of the imaging quality assessment with Fisher's exact test. CONCLUSIONS: Subjectively, the NewTom 9000 was considered by the authors to be of limited value for the evaluation of cancellous bone grafts, but to show good contrast for cortical bone grafts. The authors' subjective opinion was not supported by statistical analysis.

Facial augmentation with porous polyethylene (Medpor)--histological evidence of intense foreign body reaction.

In a previous study by our group evaluating the clinical use of Medpor implants as augmentation material in the facial skeleton, we examined cases with unexpected intense foreign body reaction and focal disintegration of the implant material. The present study evaluates the histological findings in the largest series of explanted Medpor samples from human beings so far. Altogether 10 samples were harvested during revision surgery due to aesthetic contouring or due to infection. The average time from implantation to removal of the implants was 8.1 months. Paraffin embedding was employed for improved histological analysis. Chronic inflammation and foreign body giant cell reaction were seen in all cases. Intracytoplasmatic phagocytosis of disintegrated pieces of Medpor was seen as well as focal destruction of the material. From the histological point of view it is no longer justified to regard Medpor as an immunologically inert material. Nevertheless the reaction does not seem to be severe enough to compromise the stability and volume of the implant from a clinical point of view.