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.

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.

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.

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.

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.

Histological study of tissue reactions to epsilon-caprolactone-lactide copolymer in paste form.

In previous studies, epsilon-caprolactone-lactide copolymer in solid form has been used in experimental animals as suture material, and as a biodegradable nerve guide. The aim of the study reported here was to assess tissue reactions to epsilon-caprolactone-lactide copolymer in paste form, histologically, and to compare bone healing at the sites of implantation versus that at control sites. The other purpose of the study was to evaluate the properties of the implanted material as a filling material for bone defects. Resorption time and intensity of inflammatory reaction were also evaluated. Material was implanted into the abdominal walls and femurs of 34 rats. Follow-up times were from 2 weeks to 1 year. The results showed that epsilon-caprolactone-lactide copolymer in paste form induces a severe inflammatory reaction when placed in muscle, and moderate inflammation when implanted into bone. The resorption time was more than 1 year. Bone healing at sites of implantation was slower than at control sites.

Biodegradable polylactide plates and screws in orthognathic surgery: technical note.

In orthognathic surgery, the bone fragments are usually fixed with metallic plates and screws. Metallic devices other than titanium plates are usually removed after the osteotomy has consolidated, which often requires general anaesthesia. Titanium plates, supposed to be biotolerable, have been introduced in order to overcome this need for secondary intervention. However, due to corrosion, titanium particles have been found in scar tissue covering these plates and in locoregional lymph nodes. Therefore, their removal is also advocated. Self-reinforced poly (L-lactide) homopolymer (PLLA) and poly (L/D-lactide) stereocopolymers with a L/D molar ratio up to 85/15 have sufficient strength to overcome the need for additional support for the fixation of fractures. The plates can be bent at room temperature. The surgical technique and early results of a case of bimaxillary surgery and genioplasty fixed with bioresorbable material without postoperative rigid maxillomandibular fixation are reported.

Developments in craniomaxillofacial surgery: use of self-reinforced bioabsorbable osteofixation devices.

Because of the problems associated with the conventional osteofixation devices used in craniomaxillofacial surgery, absorbable devices present an appealing alternative. Devices made of the polymers polylactide, polyglycolide, and their copolymers (PLGA and P[L/DL]LA) are currently the most commonly used. Ultrahigh-strength implants can be manufactured from these polymers with the self-reinforcing technique. Over the authors' almost two decades of study, both in experimental and clinical settings, self-reinforced devices have proved to be biocompatible, easy to handle, and mechanically strong, even for the fixation of femoral neck fractures. In craniomaxillofacial surgery, the authors have used self-reinforced devices for over 8 years without complications. Because of the more favored degradation characteristics, currently the copolymeric self-reinforced devices (P[L/DL]LA, Biosorb FX and PLGA, Biosorb PDX; Elite Performance Technologies, Solana Beach, Calif.) represent the advancing front in the application of absorbable devices in craniomaxillofacial surgery. The authors' share their experience and their studies of self-reinforced devices, which possess the highest strength and ductility of all bioabsorbable products.

Fixation of mandibular body osteotomies using biodegradable amorphous self-reinforced (70L:30DL) polylactide or metal lag screws: an experimental study in sheep.

Mandibular body osteotomies were fixed in nine sheep using new totally amorphous (70L:30DL), self-reinforced, polylactide (SR-PLA) lag screws and in nine sheep using standard stainless steel lag screws. No intermaxillary fixation was used. During follow-up, radiological, histological and microradiological studies were undertaken at 3, 6, 12 and 24 weeks. In both groups, all osteotomies consolidated at similar rates and no adverse reaction to the screws was seen. However, displacements of the fixed osteotomy fragments were common in both groups during the first 3 weeks. The biocompatibility of SR-PLA during the follow-up period was found to be good. Only initial signs of biodegradation were seen. The results of this study indicate that (70L:30DL) SR-PLA has potential for use as a fixation screw material in oral and maxillofacial surgery, and that further studies using this material are justified.

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.

The effect of osteotomy and osteosynthesis in the mandibular condyle. A radiologic and histologic study in sheep.

Eighteen oblique osteotomies in sheep mandibular condylar necks were fixed with self-reinforced poly-L-lactide (SR-PLLA) (n = 9) or stainless steel (n = 9) screws (core diameters 2.4, 2.7, 3.0, or 3.5 mm). No intermaxillary fixation (IMF) was applied. The follow-up periods were 6, 12, and 24 weeks, respectively, after which the sheep were killed, and the status of the condylar head was assessed radiographically and histologically. The results showed that the fixation had been adequate. Bony destruction, osteophytes, and flattening of the condylar head, however, were frequently observed in both groups, as compared with the unoperated contralateral condyle. Histologic studies revealed that the thickness of the condylar head cartilage had increased and that the boundaries of the different cell layers were irregular, as was the junction of cartilage and bone. The diameter of the screw did not seem to have any influence on the occurrence of either radiologic or histologic signs of condylar degeneration. These findings indicate that screw fixation of condylar fractures in the mandible without IMF might result in degenerative joint disease.

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.

Sagittal split osteotomy fixed with biodegradable, self-reinforced poly-L-lactide screws. A pilot study in sheep.

Self-reinforced poly-L-lactide (SR-PLLA) screws were used to fix bilateral mandibular sagittal split osteotomies (SSO) in six sheep. No intermaxillary fixation was used postoperatively. The follow-up time was 16 weeks, after which the sheep were killed. Both sides of the mandible were photographed and radiographed. The bending strength of the osteotomy was measured on the left side of the mandible. Histological and microradiographic studies were performed on the right side of the mandible. The results showed that the SR-PLLA screws were strong enough to fix the SSO rigidly. The bending force needed to break the bone was greater than that for the average unoperated mandible. The histological and microradiographic studies showed uneventful healing of the osteotomies in all six sheep. The results indicate that this method should be suitable for rigid fixation of SSO and fractures of the mandible in human beings.

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.

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.

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.

Skeletal stability following mandibular advancement and rigid fixation with polylactide biodegradable screws.

Skeletal stability during the first year after mandibular advancement surgery and fixation using biodegradable self-reinforced poly-l-lactide (SR-PLLA) screws, without postoperative intermaxillary fixation, was studied in 25 patients by means of cephalometric measurements. The magnitude of advancement was on average, 3.88 mm at pogonion (PG) (range 1.25-6.5 mm) and 4.57 mm at B-point (range 2.75-7.5 mm). After one year a mean relapse backwards of 0.59 mm at the PG (15%) and 0.78 mm at the B-point (17%) was observed. Nineteen patients (76%) and 17 patients (68%) were stable at PG and B-point, respectively. SR-PLLA screws are considered to be comparable to other forms of rigid internal fixation for fixation of bilateral splitting osteotomies after mandibular advancement, as far as skeletal stability is concerned.

Osteotomy site healing following mandibular sagittal split osteotomy and rigid fixation with polylactide biodegradable screws.

Follow-up of 47 patients, treated using mandibular bilateral sagittal split osteotomy and self-reinforced poly-L-lactide acid (SR-PLLA) screws for rigid internal fixation, is presented. The focus was on clinical and radiological osteotomy healing. The average follow-up time was 2.1 years (range 0.5-5 years). Clinical recovery and radiological osteotomy healing during follow-up were uneventful. Osteolytic changes were seen around the SR-PLLA screws in 27% of cases. The majority of the screw canals remained as radiolucent shadows without bony filling.

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.