Use of platelet-rich plasma under autogenous onlay bone grafts

OBJECTIVES

To analyze the healing of autogenous onlay bone grafts in three different situations, focusing on the interface area.

MATERIAL AND METHODS

Sixteen rabbits underwent autogenous bone graft surgeries in the calvaria. The block bone grafts were positioned in three different situations: direct contact between bone graft and receptor bed, graft interposed by particulate bone, and graft interposed by platelet-rich plasma (PRP). After 7, 15, 30, and 60 days, the specimens were retrieved for histological and morphometric evaluation.

RESULTS

All groups healed uneventfully and presented incorporation of the grafts after 30 days. A slightly more evident new bone formation could be observed in the PRP group in the first analyzed period, and an earlier maturation of bone in the last period, although no statistically significant differences were achieved.

CONCLUSION

The use of additional material between the bone graft and the receptor bed when using the onlay technique must be carefully considered, taking into account the size of the reconstruction and the cost/benefit relation. The addition of PRP in between autogenous bone blocks and the receptor bed did not confer significant benefit for the new bone formation and healing on the calvaria of bone of rabbits.

Experimental studies on hydroxyapatite powder-carboxymethyl chitin composite: injectable material for bone augmentation

We developed a hydroxyapatite (HA) powder-carboxymethyl chitin composite (HA-CMC composite) that can be injected with a 14G needle by adding distilled water. We prepared Materials I (HA = 57.0 wt%) and II (HA = 40.2 wt%) and examined their biocompatibility and osteoconductivity. With a 2-mm skin stab, the material was injected on the calvarial bone of rats. The periosteum was denuded blindly in half of the cases and preserved in the other half of the cases. Simultaneously, the material was injected subdermally into the abdominal skin to examine diachronic volume alteration of the material. Our results indicated that the new materials had biocompatibility as high as that achieved with previously developed HA materials. The difference in HA concentration did not influence the osteoconductivity, but the periosteum and the soft tissue on the cranium seemed to be an obstacle to bone ingrowth. On the other hand, the volume alteration was significantly smaller in Material I than in Material II. This composite may be especially useful in facial bone augmentation because it can be injected with only a small skin stab. When used for that purpose, the periosteum of the host bone should be denuded to facilitate bone ingrowth, and Material I will be preferable to Material II in terms of the maintenance of the initial volume.

Histologic examination of pedicled buccal fat pad graft in oral submucous fibrosis

PURPOSE

This report evaluates the wound healing process of buccal fat pad (BFP) grafted on a defect of the buccal mucosa for oral submucous fibrosis (OSF).

PATIENTS AND METHODS

Sixteen patients with limitation of mouth opening under the diagnosis of OSF were surgically treated by cutting the fibrotic bands on the buccal mucosa (10 bilateral and 6 unilateral). The defects created were then covered by a BFP graft. The bulging BFP was trimmed postoperatively on a weekly basis until it was fully epithelialized. The specimens were stained and examined microscopically.

RESULTS

Inflammatory cell infiltrate, blood vessel congestion, and fibrinous exudates covering the BFP were obvious by week 2. At week 3, blood vessel congestion and fat cell number decreased markedly. Evidence of stratified squamous epithelium with parakeratosis was seen in the margin of the BFP graft. At week 4, the number of fat cells decreased significantly and the original BFP was almost completely replaced by granulation tissue. The original BFP was fully covered by stratified squamous epithelium by week 5.

CONCLUSIONS

The BFP graft has been widely used for covering exposed defects created by fibrotic band excision for the improvement of mouth opening limitation. The healing process was documented microscopically by weekly observation.

Adenovirus-mediated VEGF(165) gene transfer enhances wound healing by promoting angiogenesis in CD1 diabetic mice

It has been previously shown that vascular endothelial growth factor (VEGF) plays a central role in promoting angiogenesis during wound repair and that healing-impaired diabetic mice show decreased VEGF expression levels. In order to investigate the potential benefits of gene therapy with growth factors on wound repair, a replication-deficient recombinant adenovirus vector carrying the human VEGF(165) gene (AdCMV.VEGF(165)) was topically applied on excisional wounds of streptozotocin-induced diabetic mice. Treatment with AdCMV.VEGF(165) significantly accelerated wound closure when compared with AdCMV.LacZ-treated, as well as saline-treated control mice, by promoting angiogenesis at the site of injury. Our findings suggest that AdCMV.VEGF(165) may be regarded as a therapeutic tool for the treatment of diabetic ulcers.

Impaired wound healing in mice deficient in a matricellular protein SPARC (osteonectin, BM-40)

BACKGROUND

SPARC is a matricellular protein involved in cell-matrix interactions. From expression patterns at the wound site and in vitro studies, SPARC has been implicated in the control of wound healing. Here we examined the function of SPARC in cutaneous wound healing using SPARC-null mice and dermal fibroblasts derived from them.

RESULTS

In large (25 mm) wounds, SPARC-null mice showed a significant delay in healing as compared to wild-type mice (31 days versus 24 days). Granulation tissue formation and extracellular matrix protein production were delayed in small 6 mm SPARC-null wounds initially but were resolved by day 6. In in vitro wound-healing assays, while wild-type primary dermal fibroblasts showed essentially complete wound closure at 11 hours, wound closure of SPARC-null cells was incomplete even at 31 hours. Addition of purified SPARC restored the normal time course of wound closure. Treatment of SPARC-null cells with mitomycin C to analyze cell migration without cell proliferation showed that wound repair remained incomplete after 31 hours. Cell proliferation as measured by 3H-thymidine incorporation and collagen gel contraction by SPARC-null cells were not compromised.

CONCLUSIONS

A significant delay in healing large excisional wounds and setback in granulation tissue formation and extracellular matrix protein production in small wounds establish that SPARC is required for granulation tissue formation during normal repair of skin wounds in mice. A defect in wound closure in vitro indicates that SPARC regulates cell migration. We conclude that SPARC plays a role in wound repair by promoting fibroblast migration and thus granulation tissue formation.

Type V collagen in experimental granulation tissue

To evaluate the spatial and temporal expression of type V collagen in a wound healing model, subcutaneously implanted viscose cellulose sponges in rats were used to induce granulation tissue formation. Analyses on granulation tissue were carried out on days 3, 5, 8, 14, 21, 30, 59 and 84. Acid soluble collagens were extracted and the relative amount of type V collagen was quantified by SDS-PAGE. Specific antibodies to type I, III and V collagens were used in immunohistochemistry and specific RNA probes to proalpha1(I), proalpha1(III) and proalpha1(V) collagen in in situ hybridization. Type V collagen content increased relative to type I and III collagens up to day 8 and remained at the same level for up to the three months. Type V collagen was expressed strongly in blood vessel walls as seen in immunohistochemistry. In situ hybridization showed that all of the three types of collagen were expressed mostly in fibroblast-like cells and also in rounded cells, especially type V collagen. In conclusion, type V collagen was seen in the wound healing model in increasing amounts from day 3 onwards, its localization being highly associated with blood vessels in granulation tissue and it was synthesized by fibroblast-like and rounded cells.

Vanadate ingestion increases the gain in wound breaking strength and leads to better organized collagen fibers in rats during healing

Repair of incision wounds closed by suturing is evaluated by the progressive gain in wound breaking strength. Previously the closure of open wounds in rats ingesting vanadate, an inhibitor of tyrosine phosphate phosphatases, was shown to occur with deposition of more uniformly organized collagen fiber bundles. The hypothesis of this study was that deposition of more uniformly organized collagen fibers would enhance the gain in wound breaking strength of incisional wounds. Six adult rats received vanadate-supplemented saline drinking water for 1 week before placement of two 6-cm, parallel, suture-closed wounds on their backs. Six control rats received identical wounds and were given saline drinking water. The drinking water regimen was continued for 1 week after wounding, and then wound strength was tested with a tensiometer and tissue samples were obtained for histologic evaluation. Wound breaking strength doubled in vanadate-treated rats compared with controls. Bright-field and polarized light microscopy showed that the connective tissue matrix of granulation tissue from control rats was oriented perpendicular to the surface of the skin. In contrast, the connective tissue matrix of granulation tissue from vanadate-treated rats was oriented parallel to the skin surface. The gap in granulation tissue between the edges of the wounds in the vanadate-treated rats was greater than that in controls. Electron microscopy showed that wounds in the vanadate-treated contained uniform collagen fibers that were 20 percent greater in diameter and more evenly spaced than they were in controls. It is proposed that these changes in the organization of collagen fibers within incisional wounds were responsible for the increased wound breaking strength observed in rats ingesting vanadate.

Connective tissue formation in subcutaneous cellulose sponge implants in the rat. The effect of the size and cellulose content of the implant

Granulation tissue formation was studied in viscose cellulose sponges with different cellulose contents and sizes after subcutaneous implantation in rats. Samples were removed and studied histologically and histomorphometrically 1-16 weeks after implantation. The implants with lower cellulose content and smaller size were invaded by more cells and filled with connective tissue more rapidly than those with the higher content and larger size. In larger sponge implants the beneficial effect of the lower cellulose content was more conspicuous.

Arachnoid granulations on high-resolution MR images and diffusion-weighted MR images: normal appearance and frequency

Arachnoid granulations (AGs), protrusions into the cerebral venous sinus lumen, have been reported on cerebral venography, contrast enhanced CT, and conventional MR imaging. Although thin-sliced high-resolution MR images and diffusion-weighted images are frequently obtained, there have been no detailed reports concerning AGs on these images. In this study, the frequency and positional distribution of AGs in the transverse sinus was investigated on thin-sliced high-resolution MR images, and their appearance on diffusion-weighted MR images was evaluated. At least one AG was found in 107 of 151 subjects (70.9%). No statistically significant differences were noticed between males and females or between the right and left sides. No significant correlations between age and size or between age and the number of AGs were noted. On diffusion-weighted images, all AGs showed iso-intensity to normal brain tissue, which was higher than the reported signal intensity of arachnoid cyst and lower than that of epidermoids. In conclusion, AGs are normal structures that are frequently found in the cerebral venous sinuses on high-resolution MR images. Knowledge regarding their frequency and normal appearance would be helpful to avoid confusion between pathological processes and AGs. It is also important to know that AGs are frequently found even in the younger population.

Vascularization into a porous sponge by sustained release of basic fibroblast growth factor

Vascularization into a poly(vinyl alcohol) (PVA) sponge was investigated using basic fibroblast growth factor (bFGF). This growth factor was impregnated into biodegradable gelatin microspheres for its sustained release and then the bFGF-containing microspheres or free bFGF were incorporated into PVA sponges. Following subcutaneous implantation into the back of mice, the bFGF-containing gelatin microspheres induced vascularization in and around the sponge to a significantly greater extent than that of free bFGF from 3 days after implantation. Significant ingrowth of fibrous tissue into the sponge was also observed when bFGF-containing microspheres were added to the sponge in contrast to free bFGF. Tissue ingrowth occurred into the deeper portion of the sponge over time while it accompanied formation of new capillaries. Empty gelatin microspheres had no effect on vascularization and the level of fibrous tissue ingrowth into the sponge was similar to that of the control group. It was concluded that incorporation of gelatin microspheres containing bFGF into the PVA sponge was effective in prevascularization of the sponge pores.

MRI of arachnoid granulations within the dural sinuses using a FLAIR pulse sequence

The purpose of the study was to assess the signal intensities of arachnoid granulations within the dural sinuses using the FLAIR sequence for differentiation of space-occupying lesions in and adjacent to the dural sinuses. We retrospectively reviewed MR images of the brain of 1118 consecutive subjects, ranging in age from 0 to 93 years (mean 57.2 years). Nodules within the dural sinuses with signal intensities similar to that of cerebrospinal fluid (CSF) on both T1 and T2 weighted images were defined as arachnoid granulations. The location, signal intensity on T1 weighted spin echo (SE), T2 weighted fast SE and FLAIR images, the impression on the inner table of the skull, and the size of the lesion were assessed. 112 subjects (10.0%), age range 4-89 years old (mean 58.9 years), were found to have 134 arachnoid granulations. The commonest location was the transverse sinus, with 115 granulations (85.8%). The prevalence of the granulations showed a peak in the sixth decade of age. All granulations were isointense relative to CSF on T2 weighted images and almost all lesions were isointense relative to CSF on T1 weighted images. On FLAIR images, 90.3% of the granulations were isointense relative to CSF and the other 9.7% granulations were slightly hyperintense compared with the CSF. 21 (15.7%) subjects showed impressions on the inner table; one case involved the outer table. In conclusion, arachnoid granulations were isointense or slightly hyperintense relative to CSF on FLAIR. FLAIR images are helpful in differentiating arachnoid granulations from other dural sinus lesions or skull lesions which have an intensity similar to that of CSF on T1 weighted and T2 weighted images.

Dermal microvasculature and tissue selective thinning techniques (ultrasound and water-jet) of short-time expanded skin in dogs

Certain reconstructive procedures, like auricular reconstructions, require thin and well-vascularized skin. The aims of this study were to analyze if the increased survival of expanded skin flaps was due to morphologic changes of the dermis, if thinning of short-time expanded skin was possible without harm to the microcirculation and if tissue selective cutting methods could be used to resect subcutaneous fat without damaging its vessels. Eighty-two 200-ml expanders were implanted into the trunk regions of 26 beagles and filled immediately with sterile saline. In the first series of experiments, the expansion was terminated after intervals of 0.5-5 weeks and dermal vessels were analyzed morphometrically. In the second series the expanded flaps were raised after 2 weeks and thinned solely surgically or with the additional use of an ultrasonic knife or with cutting by water jet. In contrast to sham flaps, the expanded skin showed only very few areas of necrosis and these were located superficially in most cases. The relative volume of the dermal vessels and their quantity showed a significant increase after the expansion. Additionally, the subcutaneous tissue could be thinned down to 0.4 mm with the water-jet-cutter. Findings demonstrated that the method used could create a well-vascularized skin flap of minimal thickness that could be very helpful for special reconstructive procedures.

Effect of basic fibroblast growth factor on the healing of defects in the canine anterior cruciate ligament

The effect of basic fibroblast growth factor (bFGF) on the healing of partial anterior cruciate ligament (ACL) lacerations was investigated in 17 adult mongrel canines. The defect was created in the midsubstance of both ACLs using a biopsy punch. In the bFGF group, a bFGF-impregnated pellet was sutured to the infrapatellar fat pad close to the defect. In the control group, the same pellet without bFGF was used. The healing process was evaluated macroscopically and histologically at 1, 3, 6, and 24 weeks postoperatively. In the bFGF group, a pannus-like tissue which contained abundant blood vessels extended into the defect from the adjacent synovial tissue in the early postoperative phase. Histological examination of the tissue which filled the defect revealed initial remodeling processes with a decreased number of cells and better orientation of the collagen fibers at 6-24 weeks. On the other hand, in the control group, poor healing processes were observed at each examination period. This study demonstrated that the application of a bFGF-impregnated pellet may enhance the healing potential of a partially injured ACL. Enhanced neovascularization and the formation of granulation tissue induced by bFGF early in the healing process accounted for the increased healing response.

Inhibition of wound contraction with locally injected lathyrogenic drugs

BACKGROUND

Previous studies using systematically administered lathyrogens to inhibit wound contractures have produced inconsistent results. The purpose of this study was to investigate the effects of lathyrogenic drugs on wound contraction when injected locally.

METHODS

Two symmetrical full-thickness wounds were made on the dorsum of either side of hairless (hr/hr) mice; thus, each animal served as its own control. Animals were divided into groups receiving daily local injections of beta-aminopropionitrile or D-penicillamine, or both beta-aminopropionitrile and D-penicillamine and normal saline vehicle (control side) for 5 or 10 days. The rate of contraction was determined by serial measurements of the surface area of each wound during the treatment period. At the end of the treatment period, the wounds were excised en bloc with the chest wall and prepared for blinded histological analysis. Granulation tissue thickness, number of fibroblasts in granulation tissue per unit area, number of inflammatory cells (neutrophils, lymphocytes, macrophages and mast cells) in subjacent muscle per unit area, and collagen deposition in subjacent muscle were determined.

RESULTS

Wound contraction, granulation tissue thickness, and collagen deposition in subjacent muscle were decreased only in wounds treated with beta-aminopropionitrile plus D-penicillamine. Collagen deposition in subjacent muscle was also decreased in wounds treated with D-penicillamine alone. Neither drug alone nor the combination affected the number of inflammatory cells in subjacent muscle. Body weight was not affected by the experimental procedures.

CONCLUSIONS

The combination of beta-aminopropionitrile and D-penicillamine is potentially useful for inhibiting contracture formation when injected locally.

Autologous pericranial graft resurfacing after high condylectomy and discectomy of the temporomandibular joint in rabbits

PURPOSE

This study tested the effects of an autologous pericranial graft placed over the condyle on healing after high condylectomy and discectomy.

MATERIALS AND METHODS

Sixteen young adult New Zealand white rabbits were divided into four test groups and a control group. Three animals from the test group and one control animal were killed at 2, 4, 8, and 12 weeks postoperatively. Each experimental animal received a high condylotomy and discectomy bilaterally. In addition, on one side a pericranial graft was placed on the shaved bone and immobilized with a tissue adhesive.

RESULTS

The results showed better healing of the articular defects in the joints where grafts had been placed, including earlier and more complete soft tissue covering, more substantial neochondrogenesis, and better organization of the regenerated articular cartilage.

CONCLUSION

Pericranial grafts may be helpful in facilitating healing after high condylectomy. However, technical improvements in the method of tissue fixation may be necessary.

The use of cryopreserved human skin allografts in wound healing following Mohs surgery

BACKGROUND

Immediate reconstruction has become the preferred approach to management of full-thickness cutaneous defects following microscopically controlled excision (MCE) of tumors. In a minority of patients, however, large reconstructive procedures are contraindicated, and a long-term biological dressing that stimulates healing while minimizing wound care is desirable.

OBJECTIVE

To assess the utility of cryopreserved human skin allografts (HSA) in wound care and wound healing following Mohs surgery.

METHODS

Sixteen patients were treated with HSA following MCE and followed postoperatively for evidence of infection, involution, or survival of HSA, and granulation tissue production. Follow-up was 2-26 months.

RESULTS

The use of HSA resulted in one of three general outcomes: rapid healing and rejection, subsequent full-thickness skin grafting, or persistence of HSA during prolonged healing.

CONCLUSIONS

HSA are a safe alternative to immediate reconstruction in a carefully selected population of skin cancer patients. They minimize wound care while providing continuous wound coverage during healing, and are an efficient bridge to full-thickness skin grafting.

[MRI of the intervertebral disk]

Failure to respond to conservative treatment and recurrent disease after operative intervention are the major indications for diagnostic imaging in degenerative disc disease. In recent years computed tomography (CT) has widely replaced myelography, and now CT is giving way to magnetic resonance imaging (MRI). MRI yields diagnostic information comparable to that obtained with myelo-CT, yet spares the patient the need for intrathecal contrast administration or exposure to ionizing radiation. In the postoperative spine, contrast-enhanced MRI has proven more accurate than CT in distinguishing epidural scar formation from recurrent disk herniation.

[The epidermis as a graft]

Laboratory epidermal autotransplantation was performed on the surface of a full-thickness skin defect using mongrel female rats. Epidermal graft represented suction blister roofs, formed as the result of the donor skin site treatment with lowered up to -0.6 kg/cm2 pressure. It contained all epidermal cell layers. Following 1, 7 and 28 days after the transplantation recipient bed sites containing grafted epidermis were excised and histological study war performed. It was demonstrated that epidermal graft received by the method described was able to grow as well as to differentiate on the surface of a full-thickness skin defect.

Collagen type IV and procollagen type III during granulation tissue formation: a serological, biochemical, immunohistochemical and morphometrical study on the viscose cellulose sponge rat model

The serum concentrations of collagen type IV,7S, collagen type IV,nc1, and aminoterminal type III procollagen peptide immunoreactive components were measured by means of specific radioimmunoassays during development of granulation tissue in rats. The results were compared with tissue deposition of basement membranes and interstitial collagens in the granulation as measured morphometrically. A parallel sequential pattern in tissue deposition of collagen types III and IV, and serum increase of collagen types III- and IV-related fragments, was observed. Serum collagen type IV was less sensitive as a marker for development of granulation tissue than the serum procollagen type III N-peptide. This was in accordance with a low collagen type IV/interstitial collagen ratio in the granulation tissue. However, a cross-sectional study showed that serum collagens types IV,7S and IV,nc1 may be useful as early quantitative indicators of granulation tissue formation. Simultaneously, measurement of collagen type IV- and procollagen type III N-peptide-related antigens in serum provides a differentiated reflection of the dynamic matrix processes in developing granulation tissue.

Interleukin 1 modulates collagen accumulation by rat granulation tissue cells both in vivo and in vitro

In in vivo studies 0.5 U human interleukin 1 (IL-1) was inoculated daily into a subcutaneously implanted viscose cellulose sponge. IL-1 significantly decreased the dry weight (7.8%) and the hydroxyproline content (24.2%) of granulomas. When the cultured rat granulation tissue cells were exposed to IL-1 (0.5-2.0 U/ml) their collagen production decreased to 80% of that in controls. No effect on cell proliferation was detected.

Histologic analysis of a retrieved microporous-coated femoral prosthesis. A seven-year case report

A microporous-coated femoral prosthesis with an average pore size of 80 to 100 microns was retrieved after seven years in a revision operation on a failed cemented acetabular component. The proximal anterior and lateral aspects of the implant were encrusted with bone. The bone was attached to the porous coating in regions of ingrowth. The implant was stable within the femur although most of the porous coating was not bone ingrown. There was progressive bone resorption in the proximal femur, suggestive of a reactive biologic mechanism. There was also a sizable posterior pocket of granulation tissue containing chronic inflammatory round cells associated with numerous birefringent polymeric particles. Polyethylene wear debris and acrylic cement were engulfed by multinucleated giant cells enveloping the loose cup.

Differentiation of the organic matrix in bone repair

This study describes the sequence of production and distribution of collagen, collagen types, proteoglycans, and calcium during bone repair in rabbits utilizing histologic and biochemical techniques. Proteoglycan content peaked 11 days following surgery and total collagen peaked 19 days after surgery, after which both levels decreased. Collagen Types I and III were present in the bone defect throughout the healing process but Type II was found only in the mid stages of repair. In the surrounding external callus Types I, II, and III were present, but Type III was not noted in the later stages of healing. These results are similar to those found in studies of fracture repair and developing bone.

Morphometric studies on wound healing after systemic administration of adriamycin and local application of fibrin sealant. Application of a new wound healing model using spongiosa implants

For investigations on the development of regenerative granulation tissue in wound healing a new model using bone spongiosa ("Kieler Spongiosa") implants is presented. Particular attention was devoted to developing a model which permits studies on wound healing without disturbance by foreign body reaction and infections. Two test groups of rats received four blocks of "Kieler Spongiosa" each in a symmetrical fashion in a paramedian region underneath the dorsal skin. The spongiosa blocks had previously been treated with glutaraldehyde to achieve cross-linkage of the collagenous structures of the surfaces of the spongiosa trabeculae. After one week (group 1) and two weeks (group 2) the animals were sacrificed. The spongiosa blocks were removed, fixed and evaluated in layered serial sections after decalcification. Two blocks which had been removed randomly from the back and front served for morphometric determination of the total volume of bony substance and the developed granulation tissue. Moreover, the cellular composition of the granulation tissue was morphometrically examined with regard to its content of capillaries, granulation tissue cells and inflammatory cells. The two other blocks were examined for DNA and hydroxyproline content of granulation tissue. Comparison of the two experimental groups yielded marked differences in spongiosa space infiltrated by granulation tissue and its composition. Our model was used to assess the influence of systemic administration of adriamycin and/or local application of a fibrin sealant system on granulation tissue formation and its morphologic structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Osteogenic potential of autogenic demineralized dentin implanted in bony defects in dogs

The bone morphogenetic properties of implants of autogenic demineralized dentin were evaluated. The dentin matrix was implanted as small pieces and as thin slices in experimental mandibular osseous defects in dogs. The dentin implants were obtained from mandibular incisor teeth from the same dogs used in the experiment. Experimental interradicular osseous defects were surgically created in the mandibular premolars areas. 2 of the 3 defects were filled with either pieces or slices of prepared dentin. The 3rd defect served as an unfilled control. The results indicate that all demineralized autogenic dentin implants induce bone formation. There was an increase in the osteogenic capacity of the implant when the samples were used as thin slices. The slices of dentin matrix give no evidence of resorption and were readily incorporated into the new bone deposited. The end product was represented by a trabecular bone joined to the dentin matrix slices. In the case of the small piece samples, the specimens were readily resorbed and replaced by new deposits of cancelous bone. The osteogenic capacity of the small piece samples of the dentin matrix is less efficient comparable to the thin slice samples of the same implant material.

Freeze treatment of the monkey mandibular condyle

Monkey mandibular condyles were frozen in situ and subsequently examined clinically and histologically. The frozen bone served as a structural matrix for the formation of new, vital bone. No ankylosis, open-bite deformity or loss of function was observed.

Changes in collagen types during the healing of rabbit tooth extraction wounds

Three alpha chains of type V collagen--alpha 1 (V), alpha 2 (V), and alpha 3 (V)--were initially demonstrated together with the expected collagen types I and III in the pepsin-soluble fraction of both normal mandibular bone and tooth extraction wound tissues of rabbits, as analyzed by sodium dodecyl sulfate-gel electrophoresis. The total collagen content of each extraction wound, as determined by the hydroxyproline assay, was observed to increase continuously from day 5 through day 17 and then leveled off or decreased. The ratio of type V to type I collagen was significantly higher in the initial stage of wound healing and decreased sharply down to the level of mandibular bone by day 5. The ratio of type III to type I collagen in the pepsin-soluble fraction increased and reached a maximum on day 5, whereas it was maximal on day 7 in the cyanogen bromide-soluble fraction, and thereafter decreased gradually in both fractions. The ratio for the pepsin-soluble fraction was, however, significantly higher than that for the cyanogen bromide-soluble fraction in the early stage of wound healing.

Soft tissue responses to hydroxylapatite particles of different shapes

Fifteen beagle dogs seven to 15 months of age had 0.5 g of hydroxylapatite in the form of sharp-edged particles (HA-1) or rounded particles (HA-2) implanted in buccal soft tissue pouches. Tissue specimens from each site were obtained at two weeks, six weeks, three months, and six months. A mild inflammatory response was seen at the implant sites with both particle shapes; however, inflammation resolved at a faster rate in the sites implanted with round hydroxylapatite particles.

Use of anti-basement membrane antibodies to distinguish blood vessel capillaries from lymphatic capillaries

A new method has been developed for identifying blood vessel capillaries and distinguishing them from lymphatic capillaries. Highly purified antibodies to two ubiquitous components of basement membrane--Type IV collagen and laminin--were applied to fresh-frozen and formalin-fixed tissue sections rich in blood vessel capillaries (granulation tissue), rich in lymphatic channels (small intestine and mesentery), and rich in both (skin, lung, and breast). Staining patterns were evaluated using standard immunofluorescence and immunoperoxidase techniques. Blood vessel capillaries contained intact basement membranes with linear staining for both Type IV collagen and laminin. Lymphatic capillaries, in contrast, uniformly lacked immunoreactivity with antibodies to these basement membrane components. These lymphatic capillaries, which were indistinguishable from blood vessel capillaries in both size (cross-sectional area) and shape (vessel eccentricity), were confirmed as lymphatics by dye injection studies. Our immunohistological technique detected 7-10 times more blood vessels than hematoxylin and eosin staining. Both benign and vessels than hematoxylin and eosin staining. Both benign and malignant tumors of blood vessel endothelium including two capillary hemangiomas and two angiosarcomas demonstrated extracellular linear staining for both Type IV collagen and laminin, whereas two lymphangiomas and two lymphangiectasias were negative. This method then provides a sensitive technique for detecting blood vessel capillaries in tissue sections and a reliable means of distinguishing blood vessel capillaries from lymphatic capillaries. This method may also aid in the identification of tumors whose origin is blood vessel endothelium.

Type V collagen during granulation tissue development

The collagen content, as determined by hydroxyproline assay, of experimental granulation tissue in rats was observed to increase rapidly 21 days, and less rapidly to 90 days of tissue development. Resistance of the collagen to pepsin digestion reached a maximum at 21 days, suggesting more extensive or more stable crosslinking at that time. Type V collagen and the expected collagen types I and III were present in pepsin extracts of the granulation tissue as determined by SDS-polyacrylamide gel electrophoresis. Over 3 months of tissue development the relative quantity of type V collagen, as evidenced by changes in the alpha B chain, varied in parallel with the changing vascularity of the tissue, suggesting an association with capillary endothelial cells and angiogenesis.

Fibronectin in experimental granulation tissue

The temporal appearance of fibronectin in experimental granulation tissue has been studied using the immunoperoxidase technique on material fixed in formaldehyde, embedded in paraffin and pretreated with pepsin. Furthermore, the relationship between the distribution of fibronectin and connective tissue fibres, demonstrated as either argyrophilic or red by the van Gieson method, has been investigated. Fibronectin was demonstrated as part of the fibrinous network in the sponge before the formation of granulation tissue. In the development of granulation tissue fibronectin was seen in the initial cellular stage codistributed with the newly formed fibres, first the argyrophilic fibres and later with those stained red by the van Gieson method, too. With maturation of the granulation tissue, predominated by these fibres, the amount of fibronectin was gradually reduced. The presence of fibronectin in the sponge already before the formation of granulation tissue suggests that fibronectin in the initial stage of inflammation derives from plasma. The increase in amount of fibronectin corresponding to the cellular (fibroblastic) proliferation and the formation of fibres, both argyrophilic and van Gieson positive, indicates that fibronectin in young granulation tissue is synthesized by fibroblastic cells. The relationship between the morphologically demonstrated argyrophilic fibres and van Gieson positive fibres and the biochemical type III and type I collagens is discussed.

Acute lymphocytic leukemia with prominent azurophilic granulation and punctate acidic nonspecific esterase and phosphatase activity

Cytochemical, ultrastructural, and terminal deoxynucleotidyl transferase determinations in three cases of acute lymphocytic leukemia with azurophilic granules and punctate alpha-naphthyl acetate esterase (ANAE), alpha-naphthyl butyrate esterase (ANBE), and acid phosphatase (AP) activities further described a cytochemical and morphologic variant of acute lymphocytic leukemia. The ANAE, ANBE, and AP activities appeared specially localized within cytoplasmic granules. Electron microscopy substantiated a prominence of membrane-bound dense-core cytoplasmic granules. The variegated appearance of these dense-core granules and the cytochemical profile suggest that the aberrant granules are lysosomal in nature. Both the prominent cytoplasmic granules and the older age distribution led to early misdiagnosis of myelocytic leukemia. The distinctive cytochemical/morphologic profile and the ease of misdiagnosis suggest an important morphologic variant of acute lymphocytic leukemia.

A clinical evaluation of Proplast as a periodontal implant material

Five patients received a Proplast implant in combination two- and three-wall osseous defects. In four of the cases the implant material was removed within 6 weeks due to failure to maintain primary closure over the Proplast and subsequent inflammation. One implant remained in place for 6 months with no apparent visual signs of inflammation. However, an 8 mm pocket remained, the area was reentered, and histologic sections made. The histologic sections revealed Proplast intermixed with bone, and the presence of foreign body giant cells.

Elastic tissue in early intraoral wounds

Histochemical analysis of elastic tissue in early intraoral healing of wounds demonstrated that these fibers were concentrated in the perivascular areas of granulation tissue and within newly formed connective tissues at the base of the wound. These results were consistent with previous reports indicating that the cellular origin of this tissue is smooth muscle cells or fibroblasts.

Healing of the oral mucosa with the use of collagen artificial skin

Wounds were prepared in the oral cavity of 15 rabbits and five dogs, and an enzyme-solubilized calfskin collagen was placed over the surgery sites on one side. The contralateral sides acted as controls. Results indicated that the membrane was biologically acceptable to the oral mucosa of rabbits and dogs. Th collagen did not cause any adverse reaction and may have been responsible for the clinical impression of slightly more rapid healing of the gingivae in dogs. Clinical implications of this material's utilization produce some exciting ideas for future research.

The mechanics of wound healing

This paper discusses the factors which affect the healing of wounds at the tissue and organ levels. It covers some of the problems which complicate the sequence of healing and considers the mechanisms involved in regeneration and repair of tissues. The factors associated with the stimulus and sequence of healing and their interactions are also reviewed.

Toxic effects of dental amalgam implants. Optical histological and histochemical observations

Dental amalgam and porcelain control discs were implanted in the subcutaneous tissue of rats. Amalgam implants exerted a toxic effect caused by release of metal ions which was characterized by prolonged inflammation, delayed granulation and disordered collagen formation. Dental porcelain was found to be a suitable biocompatible control which provided a bulk similar to that of dental amalgam but induced only an uncomplicated granulation response.

Microscopic study of the pulps of human teeth following vital root resection

The effects of vital root resection upon the remaining pulp were studied in twenty-six periodontally involved human molars. The pulp was extirpated 14 days after the intervention. Granulomatous tissue present in the pulp chamber protruded from the site of the exposure as a polyp in eleven cases. Mild chronic inflammatory changes were present in the coronalmost part of the radicular pulp. The apical pulp was not affected at this time interval.

Comparative study of healing and remodeling in various bones

The effects of normal physiologic stimuli on healing and remodeling in various bones of different embryogenic origin in the rabbit and dog were compared. The findings disclosed that the healing and remodeling of the tibia and mandible were consistent with the magnitude of the forces that act on these bones; namely, the tension created by muscle contraction and the compression exerted by body weight in the tibia, and masticatory compression in the mandible. The slower healing and remodeling in the maxilla was attributed to the selection of the excision of bone in the edentulous site with minimal masticatory compression and muscle-pull tension. The excision of the bone in the skull appeared to heal by fibrous tissue with no evidence of remodeling, which is consistent with the minimal external forces that act on this bone.

Evaluation of a microcrystalline collagen preparation in extraction wounds

The microcrystalline collagen preparation evaluated in this study appeared to create a slightly denser and longer lasting inflammation and to delay slightly the early phase of bone repair in this wound model. However, beneficial effects of more rapid achievement of hemostatis were also noted. On the basis of these findings, it would be of interest to compare this material with other more widely used materials, such as gelatin foam, in this wound model.

Studies concerning the hsitotoxicity of isobutyl-2-cyanoacrylate tissue adhesive when employed as an oral hemostat

An experimental study was implemented to determine the effectiveness of isobutyl-2-cyanoacrylate (bucrylate) as an oral hemostat, its influence on sequential wound healing, and its potential as a carcinogen. Segregated groups of equal numbers of male and female Long-Evans Hooded Rats underwent deep (socket) and superficial (surface) aerosol placement of bucrylate to maxillary molar extraction sites. Bucrylate proved to be an effective oral hemostat, rapidly retarding postextraction hemorrhage. Deep placement of the adhesive resulted in retarding of healing and lingering macrohistiocytic aggregates in wounds. Superficial placement of the material resulted in very little long-term macrohistiocytic response, and would healing showed little retardation. A neoplastic potential was not demonstrated for bucrylate.