Amniotic membrane reduces wound size in early stages of the healing process.

OBJECTIVE: To investigate the effects of dispase de-epithelialised, glycerol cryopreserved amniotic membrane (AM) on full-thickness skin defects, using a rat model. METHOD: Skin defects of 15 mm diameter were surgically created and measured on the scalps of 53 male rats. Animals were divided into two groups and followed for 0, 3, 7, 14 or 21 days. AM group wounds were covered with de-epithelialised AM and sodium chloride-moistened Aquacel (ConvaTec Inc.); control group wounds were covered with sodium chloride-moistened Aquacel alone. After the follow-up, wounds were measured again, serum samples were taken and wound sites were harvested for histological analysis. Systemic interleukin-4 (IL-4) levels were analysed from serum. RESULTS: On day 3, a statistically significant difference (p < 0.01) was observed in mean wound size, with wound size in the AM group smaller than in the control group (60 ± 12% vs 81 ± 13% of the original size); other time points showed no significance difference in wound size between the two groups. We could not detect differences between the groups in histological parameters or serum IL -4 levels. CONCLUSION: According to this study, AM enhances early stage wound healing in terms of wound size but its effect decreases in later phases. The IL-4 results provide no clear evidence that IL-4 contributes to the effect of AM on wound healing. DECLARATION OF INTEREST: This study was financially supported by the Competitive Research Funding of the Tampere University Hospital (Grant 9H041, 9J047). The authors have no additional conflicts of interest to declare.

Impedance spectroscopy in monitoring the maturation of stem cell-derived retinal pigment epithelium.

The development and differentiation of stem cell-derived impermeable retinal pigment epithelium (RPE) with tight junctions (TJs) is a gradual process that is, at confluence, controlled by cell-to-cell contact. The objective of this study was to evaluate the use of electric impedance spectroscopy (EIS) to follow the maturation and development of barrier function in human embryonic stem cell-derived RPE (hESC-RPE). Barrier function was assessed using EIS, permeability measurements, and microscopic inspection in intact cells and following calcium sequestration with ethylene glycol tetraacetic acid (EGTA). The results showed that the cultures with the most mature morphology had the highest impedance and the lowest permeability values. The EIS of samples of high integrity fitted well to the equivalent model of a single RC circuit, whereas the semicircular shape of the Nyquist plots was distorted for samples of lower integrity. EGTA treatment resulted in lower impedance values and changes in the shapes of plots. Our results show that EIS-as a measure of overall maturity and integrity of the epithelium-is useful when evaluating the maturity of cell cultures. It is highly warranted in future transplantation therapies and in in vitro cell culture models in drug development.

Markers of pluripotency and differentiation in human neural precursor cells derived from embryonic stem cells and CNS tissue.

Cell transplantation therapies for central nervous system (CNS) deficits such as spinal cord injury (SCI) have been shown to be effective in several animal models. One cell type that has been transplanted is neural precursor cells (NPCs), for which there are several possible sources. We have studied NPCs derived from human embryonic stem cells (hESCs) and human fetal CNS tissue (hfNPCs), cultured as neurospheres, and the expression of pluripotency and neural genes during neural induction and in vitro differentiation. mRNA for the pluripotency markers Nanog, Oct-4, Gdf3, and DNMT3b were downregulated during neural differentiation of hESCs. mRNA for these markers was found in nonpluripotent hfNPC at higher levels compared to hESC-NPCs. However, Oct-4 protein was found in hESC-NPCs after 8 weeks of culture, but not in hfNPCs. Similarly, SSEA-4 and CD326 were only found in hESC-NPCs. NPCs from both sources differentiated as expected to cells with typical features of neurons and astrocytes. The expressions of neuronal markers in hESC-NPCs were affected by the composition of cell culture medium, while this did not affect hfNPCs. Transplantation of hESC-NPC or hfNPC neurospheres into immunodeficient mouse testis or subcutaneous tissue did not result in tumor formation. In contrast, typical teratomas appeared in all animals after transplantation of hESC-NPCs to injured or noninjured spinal cords of immunodeficient rats. Our data show that transplantation to the subcutaneous tissue or the testes of immunodeficient mice is not a reliable method for evaluation of the tumor risk of remaining pluripotent cells in grafts.

Comparison of the stability of bioabsorbable and titanium osteosynthesis materials for rigid internal fixation in orthognathic surgery. A prospective randomized controlled study in 101 patients with 192 osteotomies.

The purpose of this study was to evaluate the stability of rigid internal fixation in orthognathic surgery with either bioabsorbable or titanium osteosynthesis. Orthognathic surgery was performed on 101 patients. Bilateral sagittal ramus osteotomy was performed on 55 patients using bioabsorbable osteosynthesis in 26 and titanium osteosynthesis in 29 patients. Le Fort I osteotomy was performed on 28 patients with bioabsorbable and titanium osteosynthesis in 17 and 11 patients, respectively. Bimaxillary osteotomies were performed on 18 patients (8 were fixated with bioabsorbable and 10 with titanium osteosynthesis). Poly-70L/30DL-lactide copolymer (PLDLA) consisting of 70% L-lactide and 30% DL-lactide was used as the bioabsorbable osteosynthesis material. These plates and screws were compared with corresponding titanium materials. Statistically a clear relapse tendency was seen in skeletal measurements in all patient groups but without clinical importance. Radiological follow-up time was at least 18.3 months and clinical follow-up time at least 6.3 years. The materials used did not cause any adverse reaction except in three cases, one in the bioabsorbable group and two in the titanium group where fistula in connection with the osteosynthesis material was noted resulting in removal of the materials.

Novel maxillary reconstruction with ectopic bone formation by GMP adipose stem cells.

Microvascular reconstruction is the state-of-the-art in many fields of defect surgery today. Currently, reconstruction of large bony defects involves harvesting of autologous bone causing donor site morbidity and risk of infection. Specifically, utilizing autologous adipose stem cells (autoASCs), large quantities of cells can be retrieved for cell therapy applications and the risk of tissue rejection is diminished. The authors describe the first case report of a microvascular custom-made ectopic bone flap employing good manufacturing practice (GMP) level ASCs. The patient underwent a hemimaxillectomy due to a large keratocyst. After 36 months of follow-up, the defect was reconstructed with a microvascular flap using autoASCs, beta-tricalcium phosphate and bone morphogenetic protein-2. ASCs were isolated and expanded in clean room facilities according to GMP standards and were characterized in vitro. After 8 months of follow-up, the flap had developed mature bone structures and vasculature and was transplanted into the defect area. Postoperative healing has been uneventful, and further rehabilitation with dental implants has been started. The in vitro characterization demonstrated multipotentiality and mesenchymal stem cell characteristics in ASCs. This is the first clinical case where ectopic bone was produced using autoASCs in microvascular reconstruction surgery and it will pave way for new clinical trials in the field.

Soft tissue reactions to bioactive glass 13-93 combined with chitosan.

The aim of this study was to evaluate rabbit soft tissue reactions to bioactive glass 13-93 mesh by using a histological and immunohistochemical analysis. Bioactive glass (13-93) mesh fixed with 3 wt % chitosan was implanted into the dorsal subcutaneous space of New Zealand White rabbits (n=18) for six, 12, and 24 weeks, respectively. After 6 weeks the bioactive glass remnants were surrounded by foreign-body granuloma with eosinophilic granulocytes. After 12 and 24 weeks the implanted material was mainly absorbed, but, if any particles still remained the foreign-body reaction was notably milder. Yet, a mild chronic inflammatory infiltrate was present. Matrix metalloproteinase (MMP) -2, -3, -13 and tissue inhibitory protein (TIMP-1 and -2) expressions were studied by immunohistochemistry. MMP-3, -13, TIMP-1, and -2 positivity were detected throughout the follow-up period. MMP-2 positivity was only occasionally seen in the 24 week samples, which is constitutively expressed but is not related to inductive MMP-3 and -13 cascade. The presence of eosinophilic granulocytes in some of the samples raises the possibility of an allergic reaction to the materials. MMP-3 and -13 are suggested to participate in the host reaction to either bioactive glass or chitosan.

Postoperative skeletal stability following clockwise and counter-clockwise rotation of the maxillomandibular complex compared to conventional orthognathic treatment.

Rotation of the maxillomandibular complex (MMC) and the consequent alteration of the occlusal plane (OP) angulation is a well documented orthognathic surgical design. This study presents a comparison of the long-term postoperative skeletal stability following clockwise rotation (CR), and counter-clockwise rotation (CCR) of the MMC with the skeletal stability of patients treated according to conventional treatment planning principles. The long-term postoperative skeletal stability of the (CR) group and the (CCR) group of patients were found to compare favorably with the group of patients treated by conventional treatment (CT) planning. The long-term postoperative stability of all three groups also compared well with skeletal stability reported in the literature following double jaw surgery.

Clinical, radiographic and MRI findings of the temporomandibular joint in patients with different rheumatic diseases.

The aim of this study was to investigate the condition of the temporomandibular joint (TMJ) in patients with different rheumatic diseases, and report correlations between the clinical, radiographic and magnetic resonance imaging (MRI) findings. The 67 patients were divided into four groups: 16 with rheumatoid arthritis (RA), 15 with mixed connective tissue disease (MCTD), 18 with ankylosing spondylitis (AS) and 18 with spondyloarthropathy (SPA). They were clinically examined, and panoramic tomography, lateral panoramic radiography and MRI of the TMJ were performed. MRI showed reduced articular cartilage in 25% (4/16) of RA, 0% (0/15) of MCTD, 17% (3/18) of AS and 17% (3/18) of SPA patients. Condylar changes included erosion, osteophytes and abnormal shape. Disc alterations included perforation, abnormal anterior position and decreased movement. These abnormalities were most frequent in RA patients, and least frequent in MCTD and SPA patients. Crepitation and reduced maximum opening of the mouth correlated with abnormalities of the disc and articular cartilage as shown by MRI. Severe condylar erosion in panoramic tomograms significantly correlated with MRI findings of condylar erosion (P<0.01), diminished thickness of condylar cartilage, abnormal condylar shape, and abnormal shape of the temporal surface of the TMJ (P< or =0.001). The presence of crepitation, limited mandibular movement and/or pain on movement of the jaw often indicated structural damage to the TMJ. Panoramic radiographs provide an alternative method to MRI but, to obtain a more detailed anatomic picture, MRI is recommended for patients with acute unexplained pain or as part of preoperative work up. A panoramic recording is not indicated when MRI is planned.

A histological and immunohistochemical study of tissue reactions to solid poly(ortho ester) in rabbits.

In many cases only the temporary presence of a biomaterial is needed in tissue support, augmentation or replacement. In such cases biodegradable materials are better alternatives than biostable ones. At present, biodegradable polymers are widely used in the field of maxillofacial surgery as sutures, fracture fixation devices and as absorbable membranes. The most often used polymers are aliphatic polyesters, such as polyglycolic acid (PGA) and polylactic acid (PLA). Poly(ortho ester) is a surface eroding polymer, which has been under development since 1970, but is used mostly in drug delivery systems in semisolid form. The aim of this study was to evaluate the tissue reactions of solid poly(ortho ester) (POE), histologically and immunohistochemically. Resorption times and the effect of 2 different sterilization methods (gamma radiation and ethylene oxide) upon resorption were also evaluated. Material was implanted into the tibia and subcutaneously into the mandibular ramus area of 24 rabbits. Follow-up times were 1-10, 14 and 24 weeks. Histological studies showed that POE induces a moderate inflammation in soft tissue and in bone. At 24 week follow-up, inflammation was mild in soft tissue and moderate in bone. In immunohistochemical studies, no highly fluorescent layer of tenascin or fibronectin was found adjacent to the implant. Resorption of gamma-sterilized rods was faster than ethylene oxide-sterilized rods. The total resorption time was more than 24 weeks in both groups. Clinically the healing was uneventful and the implants the well tolerated by the living tissue. This encourages these authors to continue studies with this interesting new material to search for the ideal material for bone filling and fracture fixation.

The copolymer of epsilon-caprolactone-lactide and tricalcium phosphate does not enhance bone growth in mandibular defect of sheep.

In the field of craniomaxillofacial and orthopaedic surgery there is a constant need for bone or bone substitute. At the present, the most effective way to enhance bone healing clinically is to use autogenous bone grafts. The problems associated with the use of these autografts are donor site morbidity, limited supply and need for a second operative site. Currently there are several different synthetic products commercially available in the market; nevertheless, none of them is ideal for filling bone defects. Therefore, search for new synthetic materials for bone replacement is necessary. A mixture of tricalcium phosphate (TCP) and epsilon-caprolactone-lactide copolymer P(epsilon -CL/DL-LA) was prepared and implanted in critical size mandibular bone defects in twelve sheep. Contralateral side was used as a control. Follow-up times for histological and radiological studies were 9, 14, 24 and 52 weeks. We found that the implanted material did not enhance bone formation compared to control site. We also confirmed that defect size was of critical size, since there was no complete healing of the control site either. The results do not encourage us to continue our studies with the mixture of TCP and P(epsilon-CL/DL-LA) as a filling material for bone defects. Therefore the search for the ideal material is still ongoing.

Biodegradable polydioxanone and poly(l/d)lactide implants: an experimental study on peri-implant tissue response.

Several implants for orbital wall fracture treatment are available at the present, but they have drawbacks: resorption, risk for migration and foreign body reaction. Alloplastic resorbable implants would be advantageous: no removal operation and no donor side morbidity. The purpose of this study was to evaluate the foreign body reaction, capsule formation and mechanical properties of two bioresorbable implants. PDS and SR-P(L/DL)LA mesh sheet (70/30) with solid frame (96/4) implants (SR-P(L/DL)LA 70,96) were placed into subcutaneous tissue of 24 rats. Immunohistochemistry was used to evaluate reactivity for Tn-C, alpha-actin, type I and III collagens and two mononuclear cells: T-cells and monocyte/ macrophage. GPC, DSC and SEM were performed. Student's t-test or nonparametric Kruskall-Wallis test were used for statistical analysis. Histology of peri-implant capsule exhibited an inner cell-rich zone and an outer connective tissue zone around both materials. Tn-C reactivity was high in the inner and alpha-actin in the outer zone. At the end of the study, the difference of type I collagen versus type III collagen reactivity in inner zone was statistically significant (P<0.0001) as was the difference of type I collagen versus type III collagen reactivity in outer zone (P<0.0001). Immunohistochemistry did not reveal any statistical differences of T-cell and monocyte/macrophage reactivity around PDS versus SR-P(L/DL)LA 70,96 implants, nor any differences as a function of time. PDS were deformed totally after 2 months. SR-P(L/DL)LA 70,96 implants were only slightly deformed during the follow up of 7 months. PDS degraded rapidly in SEM observation. Particles were detaching from surface. SEM observation revealed that polylactide implant was degrading from the surface and the inner porous core became visible. The degradation came visible at 7 months. There were cracks in perpendicular direction towards to the long axis of the filaments. M(w) of PDS decreased fast compared to the polylactide implant. Foreign body reaction was minimal to both materials but continued throughout the whole observation period. Mechanically PDS was poor, it looses its shape totally within 2 months. It cannot be recommended for orbital wall reconstruction. New mesh sheet-frame structure (SR-P(L/DL)LA 70,96) approved to be mechanically adequate for orbital wall reconstruction. It seems not to possess intrinsic memory and retains its shape. The resorption time is significantly longer compared to PDS and is comparable to other studied P(L/DL)LA copolymers. Thus, the new polylactide copolymer implant may support the orbital contents long enough to give way to bone growth over the wall defect.

Tyrosine derived polycarbonate membrane is useful for guided bone regeneration in rabbit mandibular defects.

Standardized bilateral through-and-through defects (12x6 mm) were created extraorally in the mandibular angle of 18 New Zealand White rabbits. Animals were divided in to three groups (n=6) according to the intended healing time. On the left side, defects were covered with a poly(desaminotyrosyl-tyrosine-ethyl ester carbonate) (PDTE carbonate) membrane wrapped around the inferior border of the mandible and fixed with bioabsorbable sutures. On the right side, the defects were filled with a mesh made of bioactive glass 13-93 and 3 wt% chitosan. The defects were covered with the same membranes. Periosteal flap was sutured over the membrane. Radiographically, bone ingrowth was seen in all specimens at 12 weeks postoperatively. At 24 weeks, completely ossified area remained approximately at the same level as at 12 weeks, but the non-ossified area decreased to almost zero. However, the bioactive glass mesh did not improve the results. Nevertheless, enveloping the defect with PDTE carbonate membrane seemed to play a crucial role in new bone formation. Based on these results, we conclude that tyrosine polycarbonate is a promising new material for guided bone regeneration.

Are there any complications with bioabsorbable fixation devices? A 10 year review in orthognathic surgery.

Bioabsorbable fixation devices have been used in our departments between November 1991 and November 2001 in orthognathic surgery. The aim of this retrospective study was to assess all complications experienced during this time period, when we have operated 163 patients who have undergone 329 orthognathic osteotomies fixated with bioresorbable devices. No postoperative intermaxillary fixation was used. Light guiding elastics were used for 5 to 7 weeks. Patients' acceptance was generally excellent and very few complications occurred during this follow-up of 10 years. The complications were minor and did not affect the end results of the operations. Minor complications occurred in 14 patients (8.6%). Only one patient (0.6%) had a postoperative infection with elevated infection parameters. The other minor complications consisted mainly of dehiscence of the wound and plate exposure together with granulation tissue in the operation field. The rest of the complications occurred in the beginning of our study, when large screw heads on top of the bone irritated the patient and had to be removed. Insufficient fixation resulted in open bite in three patients (1.8%) in the beginning of the trial use of new devices, which no longer are used. Based on our experience, bioresorbable devices are safe to be used in orthognathic procedures. However, there is a learning curve, as there is with all new methods introduced.

HLA-DRB1* alleles and temporomandibular joint erosion in patients with various rheumatic diseases.

OBJECTIVE: To investigate the association between HLA antigens and temporomandibular joint (TMJ) erosion, salivary composition, and focal sialadenitis in patients with rheumatic diseases. METHODS: Eighty-four patients, 24 with rheumatoid arthritis (RA), 19 with mixed connective tissue disease (MCTD), 19 with ankylosing spondylitis (AS), and 22 with spondyloarthropathy (SPA) were studied. Each patient underwent clinical examination of the masticatory system, unstimulated and stimulated saliva collection, and minor salivary gland biopsy. Radiographs (OPTG) of the TMJ were obtained, and HLA allele (A, B, C and DRB1*) analysis was performed. Erosion in OPTG was scored from 0 (no erosion) to 4 (condyles totally eroded). In the analysis, scores 0-2 were grouped as normal or mild changes, and scores 3-4 as distinct erosions. One hundred healthy blood donors served as controls for HLA typing. RESULTS: Distinct erosion of the TMJ in OPTG was observed in 22 (27%) patients. It affected four (17%) of the 24 patients with RA, three (17%) of the 18 with MCTD, seven (37%) of the 19 patients with AS and eight (38%) of the 21 with SPA non-significant (NS). The mean erosion scores were 1.7 for RA, 1.3 for MCTD, 2.5 for SPA, and 1.6 for AS patients [probability (p) = 0.04]. The frequency of HLA-B27 antigen was higher in the AS and SPA patients, and that of HLA-DRB1*04 allele higher in RA patients than in control subjects. In the whole patient population, HLA-DRB1*01 allele was significantly associated with erosions 16/36 (44%) versus 6/46 (131%1) (p = 0.0014). In the SPA group, patients with HLA-DRBI*01 allele had a significantly higher occurrence of distinct erosions than patients without this allele [8/10 (80%) versus 0/11 (0%) (p = 0.0002)], whereas DRB1*06 was protective [0/8 (0%) versus 8/13 (62%) (p = 0.018)]. HLA-DRB1*04 was associated with increased salivary IgG in the RA patients. CONCLUSION: HLA antigens are significantly associated with the development of destructive lesions in the TMJ, as well as composition of saliva in patients with various rheumatic diseases.

Bacteremia after plate removal and tooth extraction.

Our aim was to investigate the occurrence of bacteremia associated with removal of a semirigid osteosynthesis plate and an adjacent third molar. Ten patients with fixed mandibular angle fracture were bacteriologically sampled from the second molar's distal gingival pocket, from the third molar's extraction socket and from the osteosynthesis plate. Blood samples from the ante-cubital vein were taken 10 times until 30 min postoperatively. Established culture, isolation and identification methods for the bacterial species were used. Bacteremia was detected in 60% of the subjects, most frequently 1.5 min after removal of the plate (20%) and 1.5 and 5 min after extraction of the tooth (20%), but also 10 min (10%) and 30 min (10%) postoperatively. 13 different bacterial species or groups were isolated, mean 2.5 +/- 1.9 per bacteremia-positive subject. The majority (85%) were anaerobes with Actinomyces, Campylobacter and Lactobacillus species predominating. In all the blood culture-positive cases the corresponding species was also recovered from one or more of the oral samples. These results show that oral surgical procedures are associated with a high frequency of longstanding anaerobic bacteremia, which could be harmful in patients at risk.

Orbital floor reconstruction with poly-L/D-lactide implants: clinical, radiological and immunohistochemical study in sheep.

In this study the reconstruction capacity of orbital wall in sheep was evaluated when poly-L/D-lactide (PLDLA96) implants were used for large blow-out defects in 18 sheep. The contralateral side, where the defects healed spontaneously, served as controls. The follow-up was 12, 16, 22 and 36 weeks. Healing was evaluated clinically, radiologically, histologically and immunohistochemically. Physiochemical properties of the implants were also studied. At first, the implants were surrounded by elastic capsules, which gradually ossified. At 36 weeks, 60% were still visible and deformed but surrounded by bone. Light microscopy revealed a low grade inflammatory reaction. Expression of Tn-c and cFn was intense throughout the study. Shear strength decreased gradually and was not measurable after 16 weeks. Crystallinity increased steadily from 1.5 to 29.30% and molecular weight decreased from 49,000 to 4186. In CT, the final bony defect was smaller in the reconstructed sides than in the controls. Based on this study it can be concluded that PLDLA96 implant provokes a local inflammation, which does not prevent bone healing. The deformation of the implant, however, indicates that this PLDLA96 plate is not suitable for orbital floor reconstruction.

Local primary (AL) amyloidosis in the palate. A case report.

Oral amyloidosis is usually presented in the tongue and is often regarded as a paraneoplastic phenomenon. We present a rare case of primary local amyloidosis in the palate of an 80-year-old male. No simultaneous general illnesses or malignancies were detected in spite of extensive assessments by specialists in internal medicine.

Is the incidence of oral and pharyngeal cancer increasing in Finland? An epidemiological study of 17,383 cases in 1953-1999.

OBJECTIVE: The aim of this study was to describe the occurrence of oral and pharyngeal cancer in Finland over the last half century. MATERIALS AND METHODS: The study included all lip, oral and pharyngeal cancer cases diagnosed in Finland and reported to the nation-wide Finnish Cancer Registry between 1953 and 1999. RESULTS: The study comprised 17,383 new cancer cases: 11,666 in males and 5717 in females. Of these, 83% were squamous cell carcinomas. By the end of the study, 1999, the mean age at diagnosis had increased to 63 years for males and 67 for females. The age-adjusted incidence of oral and pharyngeal cancer decreased in males from 12.5 per 10(5) to 8.4 per 10(5) while it increased in females from 3.0 per 10(5) to 3.9 per 10(5). This was because of a decrease in lip cancer incidence in males, while the incidence of tongue, mouth and salivary gland cancers increased in both genders. The annual number of new oral cancer cases increased, however, in both genders. CONCLUSION: The incidence of lip cancer decreased in males, probably because of a decrease in smoking and in outdoor work. The incidence of intra-oral cancers increased in both genders, possibly because of increased alcohol consumption.

Use of hydroxylapatite/ polymer-composite in facial bone augmentation. An experimental study.

On purpose to achieve better and more controlled alveolar ridge augmentation, biodegradable polyglycolide (PGA) curved implants with porous, particulate hydroxylapatite (HA) were developed to be used in an experimental augmentation in sheep mandible. Prior to surgery curved PGA implants were loaded with particulate HA with help of a rather fast degrading adhesive, polyglycolide/polylactide (PGA/PLA) copolymer. This augmentation device was inserted into the ridge using a slight modification of the tunnelling technique. Macroscopically, a dehiscence with loss of HA particles was observed in 3 of the 16 augmentations. Bone ingrowth was seen in a noticeable degree in one sheep at 24 weeks. Instead, foreign body-type cells were shown at the interface of mandibular bone and hydroxylapatite deposit, as well as abundant connective tissue reaction inside HA deposits. The results of the study give rise to concern about bony integration in the presence of biodegradable polyglycolide substances in HA augmentation. The findings call in question even their use as a carrier for bone forming agents in combination with HA.

Effectiveness of operative treatment of internal orbital wall fracture with polydioxanone implant.

Many implants, some made from teflon or silicone, have been used for internal orbital wall reconstruction. Late complications relating to use of such implants have been reported. In this prospective study a polydioxanone (PDS) implant absorbable in vivo was used for internal orbital wall reconstruction. Follow-up involved clinical examination, magnetic resonance imaging (MRI) and computerized tomography (CT). Clinical examinations were undertaken before operation and up to 36 weeks postoperatively. Sixteen consecutive patients (10 pure blow-out fractures, six with associated zygomatic fracture) took part in the study. Prevalences of diplopia, proptosis and enophthalmus were recorded during each follow-up examination. This study revealed no muscle entrapment within the fracture line. Although CT results confirmed bone growth in the internal orbital wall, shape was unsatisfactory, and orbital volume was not reduced. MRI revealed thick scar formations in six cases (37.5%), fibrotic sinuses filled with air or gas in three cases (19%) and a fibrotic sinus with fluid around the PDS in one case (6%). Our results suggest that use of PDS in reconstructing the internal orbital wall is inadvisable.