An experimental and clinical study of Ossocol, a compound of hydroxylapatite and collagen]

Experiments on white rats revealed that introduction of Ossocol, a sponge with a composition of hydroxyl apatite with collagen, into a removed tooth well prevented mandibular atrophy and was conducive to a more smooth defect filling with better compact bone tissue. Ossocol use in 214 patients with bone tissue defects developing after tooth removal, of odontogenic cysts, sequestra, and after radical surgery for periodontal diseases demonstrated a positive effect of this agent on the course of the postoperative period: the defect was more rapidly replaced by bone tissue. No unfavorable local or general reactions to Ossocol implantation were observed.     

The "Eve" procedure: the transfer of vascularized seventh rib, fascia, cartilage, and serratus muscle to reconstruct difficult defects

Very few microvascular units entertain the possibility of simultaneous vascularized transfer of bone, cartilage, muscle, and gliding fascia. In exceptionally complex conditions with loss of an essential joint, adjacent bone and functional muscle, reconstruction of all these structures at once may be necessary. At the same time, gliding tissue is often required to cover tendons. Reconstruction in one sitting prevents formation of dense scar tissue due to multiple interventions. Additionally, less bone resorption is seen if vascularized bone is used. Therefore, a more undisturbed tissue composition at the end is guaranteed. Moreover, rapid rehabilitation of moving function is possible with improvement in the final result. Finally, morbidity is lowered by using a single donor site, and costs are minimalized. We present four unique cases in which the seventh rib including the costochondral junction with overlying serratus muscle, branches of the thoracicus longus nerve, and adjacent fascia have been transferred as a microvascular unit to reconstruct two severely damaged hands and two other complex injuries. In analogy with the Bible story of the creation of "the woman," it is called the "Eve" procedure. The vascularized rib was used to reconstruct a first and fourth metacarpal bone, the ascending ramus of the mandible, and the clavicle. The rib cartilage was sculptured in four cases to reconstruct an articular surface. The serratus muscle served as coverage and filling for lost tissues. It also was used as a soft bed for facial nerve repair. In two cases muscle reinnervation was performed. The fascia provided gliding tissue surrounding reconstructed tendons or articular surfaces. In all cases a high degree of function was obtained with a good cosmesis. Rehabilitation was uneventful, and no reinterventions have been necessary. Donor-site morbidity was low. Therefore, this flap proved to be successful in complex injuries where bone, cartilage, muscle, and gliding tissue were needed simultaneously. Dynamic reconstruction was attempted in two cases and was successful in one.     

A histomorphometric and histologic analysis of the implant interface in five successful, autopsy-retrieved, noncemented porous-coated knee arthroplasties

Five clinically successful, primary uncemented porous-coated anatomic knee implants were retrieved postmortem, 13-56 months after implantation, and were sectioned and evaluated histologically and histomorphometrically for bone ingrowth. The prosthesis-bone interface was divided into the following four zones: (1) the tissue prosthetic surface interface; (2) the beaded area; (3) the immediate beadless area; and (4) the marrow space. Although fibroosseous ingrowth was present in all cases, it varied quantitatively with each case and component. Average component bone ingrowth for the prosthesis interface (Zones 1 and 2) of patellae was 29%; tibias, 6%; and femora, 8%. In Zone 3, the percentage of bone apposed to the prosthesis for the patellae was 53%; tibias 36%; and femora, 32%. Zone 4, the marrow space, was not quantitated. The fibrous tissue filling nonbone-ingrown porous space in Zone 2 appeared "ligamentoid," connecting bone to beads within Zone 2 and between Zones 2 and 3. Zone 3 exhibited a bony plate formation parallel to the prostheses. No significant inflammation was noted. Overall there was more bone ingrowth into Zone 3 than Zones 1 and 2 with greater bone ingrowth found in the patellar components. The implant interface in clinically successful noncemented porous-coated prostheses of this design is characterized histologically by a noninflammatory fibroosseous ingrowth of varying degrees, and the fibrous component of this composite structure exhibits a highly organized pattern.     

Morphology and matrix composition during early tendon to bone healing

This study outlines the early morphologic phenomenon of tendon to bone healing in the rabbit model. Twelve skeletally mature, male New Zealand White rabbits received transplantation of the hallucis longus tendon into a 2-mm calcaneal bone tunnel. The morphologic characteristics of the healing tendon to bone interface were evaluated at 1, 2, 4, and 6 weeks after surgery by the use of conventional histology and immunohistochemical localization of collagen Types I, II, and III. Histologic analysis illustrated progressive maturation and reorganization of the tendon to bone interface with subsequent development of tissue collagen fiber continuity between the tendon and bone. Initially, diffuse immunolocalization of all three collagen types was observed within the scar tissue filling the space between the tendon and bone. During a 6-week period, reorganization of the scar tissue into an interface occurred, similar to an indirect insertion. Although a definitive fibrocartilage region did not form, Type II collagen was localized at the remodeling insertion site throughout the first 6 weeks of repair. In addition, Type III collagen fibers, resembling Sharpey's fibers, were noted to span this interface. The characterization of the insertion between tendon and bone is important to the understanding of healing in commonly used orthopaedic grafting procedures, such as anterior cruciate ligament reconstructions.     

Periradicular healing in response to Diaket root-end filling material with and without tricalcium phosphate

The healing of the periradicular tissues was evaluated when the polyvinyl resin Diaket with and without tricalcium phosphate was used as surgical root-end filling material. Non-surgical root canal treatment was performed on 56 mandibular premolar roots in mongrel dogs. Following root-end resection, root-end cavity preparations were filled with Diaket, the comparative material, or Diaket in combination with tricalcium phosphate, the experimental material. Postsurgically, healing of the tissues adjacent to the filling materials and in the surrounding surgical site were evaluated at 30 and 60 days. There was virtually no statistically significant difference between the experimental and comparative group at or within the 30- or 60-day period with regard to inflammation, connective tissue formation, root-end encapsulation, cementum formation, or bone apposition. Findings suggest that cementogenesis occurred over both materials. The overall healing of the periradicular tissues was favourable.     

Combined bronchoalveolar-vascular casting of the canine lung

Canine bronchoalveolar and vascular corrosion casts were prepared using unfixed tissue and Dow-Corning Room Temperature Vulcanizing Silastic 734. The casts were observed using stereo light microscopy and scanning electron microscopy. The casts show the relationship between the vasculature and airway and demonstrate intricate microanatomical details. Also, microvasculature filling was enhanced using unfixed tissue as compared to my previously described technique using fixed tissue. Prewashing the microvasculature with cold phosphate buffered saline appeared to facilitate microvascular filling with silicone rubber. The described method is useful for rapidly making durable models for studying the normal respiratory airway and microvasculature. It should be useful in future studies of diseased pulmonary tissue as well as other normal and diseased tissues where microanatomical relationships between microvasculature and adjacent luminal structures are relevant.     

Enhancement of bone formation in the setting of repeated tissue deformation

The purpose of this study was to investigate whether the osteoinductive recombinant human bone morphogenetic protein 2, combined with a collagen carrier, could enhance bone formation when exposed to controlled amounts of tissue deformation. Chambers that allow for the multiple harvestings of tissue specimen were used. The devices were implanted in the tibial metaphyses of skeletally mature New Zealand White rabbits. A tissue ingrowth canal in each device either was left empty or filled with a collagen carrier with or without 0.6 microgram of recombinant human bone morphogenetic protein 2. The tissue ingrowth canal was deformed cyclically during a period of 2 minutes daily, according to a previously described deformation protocol. The tissue that developed in the chambers was harvested every 3 weeks. Undecalcified histologic sections of each tissue sample were stained with trichrome and von Kossa stains and subjected to histomorphometric analysis. It was found that deformation decreased the area occupied by bone trabeculae in the empty chambers and carrier controls. The amount of bone formed in the chambers treated with bone morphogenetic protein 2 was significantly greater than that in the chambers subjected to micromotion and left empty or implanted with the collagen carrier. The amount of bone in chambers with motion and bone morphogenetic protein 2 was equal to that in chambers left empty and not subjected to micromotion. Qualitative histologic analysis of the bone formed with bone morphogenetic protein 2 revealed normal bone trabeculae. These findings indicate that bone morphogenetic protein 2 may be useful in augmenting bone formation in conditions that otherwise would favor the formation of fibrous tissue.     

Methods of immediate reconstruction of the separating dividing mechanism in extended horizontal resection of the larynx

The experiments on unanesthetized rats have established that the intravenous injection of verapamil in a dose of 0.6 mg/kg during 30-minute carotid occlusion with subsequent recirculation prevents postischemic hypoperfusion, normalized oxidative processes and prevents brain tissue edema. In patients with transient cerebral circulatory disorders, a single injection of verapamil in a dose of 10 mg enhances the pulse filling of cerebral vessels. During a course therapy, the drug decreases minor and middle vessel tone, increases the REG amplitude, lowers the interhemispheric asymmetric blood filling rate, and enhances the functional resistance of cerebral vessels.     

Healing of the anterior attachment of the rabbit meniscus to bone

In a rabbit model the healing process of the anterior attachment of the medical meniscus was observed during the first 12 weeks after sharp transection and refixation in a tibial bone channel. Evaluations of the healing tissue were histologic analysis, application of immunohistochemical methods to show collagen types and nerve regeneration, and mechanical load to failure tests. Secondary changes to knee joint cartilage, as signs of eventual dysfunction of the refixed meniscus, were evaluated by analysis of proteoglycan fragment concentration in joint fluid and histologic analysis of knee joint articular cartilage and synovium. The healing tissue between the refixed attachment and bone matured from highly cellular, nonspecific granulation tissue at 1 week, to bone, fibrocartilaginous, and fibrous tissues, which at some sites developed an insertion specific tissue arrangement within a 12-week period. However, the irregular interface between the fibrocartilaginous tissue and the underlying bone, which is typical for a normal insertion, was not reestablished. Labeling for collagen Types I and II in the newly formed insertion did not return to normal. In addition a few collagen fibers connected the refixed attachment tissue to bone. New bone formation turned the initially cancellous bone tunnel walls into more solid cortical bone. However, new bone formation did not fill the distal part of the channel. The refixed meniscal attachment underwent necrosis and was revitalized by cell ingrowth from the periphery. Nerve fibers were found in the newly formed insertion by 12 weeks. The failure load at tensile testing never reached more than 20% that of a normal attachment. Degeneration of articular cartilage and increased proteoglycan fragment in the joint fluid were common after this procedure. These data suggest that, despite the focal appearance of insertion specific tissues and healing of collagen fibers to bone, the tissue architecture of a normal meniscal insertion and a normal meniscal joint protective function were not reestablished.     

Age dependent possibilities for healing in cartilage injuries (experimental investigations with animals) (author's transl)

Regenerative and degenerative changes of cartilage were studied in animals by micromorphological methods and autoradiography. Cartilage lesions of defined size were set in the femoral condyle of rabbits of variing age by means of an electrical drill developed by us. We used juvenile animals, 3 months old, and senile animals 4 years old. The lesions were studied by lightmicroscopy, electronmicroscopy and scanning electron microscopy. In young animals we were able to demonstrate prevailing reparative changes after injury and the potency for genuine regeneration originating from cartilage. Isolated chondral lesions develop reactive tissue originating mainly from superficial parts of the cartilage. When subchondral bone is exposed we see granulation tissue filling up the defect and change by metaplasia. The replacing tissue originating from superficial cartilage as well as from subchondral bone is able to fill the defect within 3 months. In the replacing tissue originating from cartilage we find fibroblasts and fibrocytes with many mitoses. Consecutively the cells are rounding increasingly. Finally chondrocytes are developing. At the same time as these reparative changes occur we see degenerative changes with decreased mucopolysaccharide synthesis, cell necroses with consecutive decrease in number of cells and singular small cluster. In old animals we could not demonstrate any reparative or regenerative changes after injuries; the artificial defect in cartilage persists. Instead, degenerative changes with signs of arthrosis are developing rapidly: chondroitin sulfate synthesis is decreased, there is ample cluster formation, cell necrosis, decrease in number of cells, and incorporation of paraplasmatic substances in cartilage. We could not demonstrate any mitoses. The causes for the inability of cartilage of aged individuals for reparative changes are discussed.     

Unusual endocrine presentations of nasopharyngeal carcinoma

BACKGROUND: Nasopharyngeal carcinoma is endemic in Southern China and the majority of patients present with local symptoms due to the tumor. METHODS: This report describes two unusual cases of occult nasopharyngeal carcinoma in which the patients initially presented with endocrine manifestations. RESULTS: The first patient presented with Cushing's syndrome secondary to ectopic adrenocorticotropic hormone (ACTH) production. Nasolaryngoscopy showed a growth in the left nasal fossa and biopsy revealed a poorly differentiated nasopharyngeal carcinoma that exhibited positive immunostaining for ACTH. The second patient presented with a 10-month history of bone pain over both lower limbs. She was normocalcemic but her serum alkaline phosphatase was markedly elevated. A bone biopsy showed both osteoclastic and osteoblastic activity with widespread fibrosis suggestive of Paget's disease. Three months later, she developed third cranial nerve palsy. Computed tomography investigation revealed a soft tissue mass filling the sphenoid and ethmoid sinuses. Biopsy showed a poorly differentiated nasopharyngeal carcinoma. The bone biopsy was reviewed and immunohistochemistry demonstrated the presence of cells positive for the epithelial marker AE1/3 within the fibrous stroma. Radio-labeled in situ hybridization showed that Epstein-Barr virus early RNA was present in these tumor cells and the bone lesions were in fact metastases. CONCLUSIONS: Nasopharyngeal carcinoma can present with rather atypical symptoms that may lead to a delay in diagnosis. Therefore, in high risk populations, it is important to consider nasopharyngeal carcinoma as a possible primary tumor in patients with occult carcinomas.     

Osteoma of the promontory: a case report

Cutaneous ossification is a rare phenomenon in collagen diseases, despite the rather frequent occurrence in these diseases of dystrophic calcinosis. We observed metaplastic woven bone formation associated with calcification in biopsy material obtained from a 49-year-old woman suffering from mixed connective tissue disease together with multiple subcutaneous indurations. This is the first case of the presence of metaplastic bone formation in a patient with mixed connective tissue disease.     

Pannus development in adjuvant arthritis of the rat - an autoradiographic study (author's transl)

After the injection of complete adjuvant, rats develop arthritis with increased proliferation of synovial tissue cells at the attachment of the synovial membrane to cartilage and bone. From this synovial tissue a connective tissue pannus develops which covers the cartilage surface as a monocellular or multicellular layer of proliferating cells. Areas with cartilage destruction are usually characterized by a great number of proliferating connective tissue cells. Cartilage destruction is not restricted to the superficial pannus, since granulation tissue of the subchondral bone may also participate in cartilage resorption. The quantitative determination of 3H-thymidine labelled chondrocytes excludes participation of these cells in pannus formation.     

Effect of root canal contents on healing of teeth with dentin-bonded resin composite retrograde seal

Healing results were compared among 551 infected roots apically sealed with a dentin-bonded resin composite (Gluma-Retroplast). These roots contained either 1) root filling to apex after resection, 2) insufficient root filling, or 3) empty root canals with necrotic pulp remnants. At 2- to 4-yr follow-up, complete bone healing was found to be 92%, 85%, and 81% in groups 1, 2, and 3, respectively. The results from groups 1 and 3 were significantly different, and the results from group 2 did not differ significantly from that of groups 1 or 3. Reasons for "Failures" were found to be mainly loose filling or uncovered canal. After 21 roots classified as "Failures" were reoperated, 76% of these showed "Complete Healing" after 1 yr.     

Prediction of mechanical properties of the cancellous bone of the mandibular condyle

The mechanical properties of cancellous bone depend on the bone structure. The present study examined the extent to which the apparent stiffness of the cancellous bone of the human mandibular condyle can be predicted from its structure. Two models were compared. The first, a structure model, used structural parameters such as bone volume fraction and anisotropy to estimate the apparent stiffness. The second was a finite element model (FEM) of the cancellous bone. The bone structure was characterized by micro-computed tomography. The calculated stiffnesses of 24 bone samples were compared with measured stiffnesses. Both models could predict 89% of the variation in the measured stiffnesses. From the stiffness approximated by FEM in combination with the measured stiffness, the stiffness of the bone tissue was estimated to be 11.1 +/- 3.2 GPa. It was concluded that both models could predict the stiffness of cancellous bone with adequate accuracy.     

Tendon interposition in a juxta-epiphyseal fracture of the proximal phalanx

PURPOSE: To report the clinicopathologic features of intraocular osseous production in association with proliferative vitreoretinopathy. METHOD: The clinical and histopathologic features of two patients with proliferative vitreoretinopathy and intraocular bone formation are reviewed. RESULTS: Preretinal osseous tissue incorporated in the proliferative vitreoretinopathy was surgically removed in one patient, and osseous tissue was present in the proliferative vitreoretinopathy in the enucleated eye of the other patient. CONCLUSIONS: Bone formation, presumably from metaplastic retinal pigment epithelium, may be present in proliferative vitreoretinopathy tissue. The intraocular bone is present internal rather than external to the neurosensory retina.     

Air in the bone? Diagnosis and treatment of a pneumatocyst of the ilium. Apropos of a case

We present a case of symptomatic pneumatocyst of the ilium observed in a professional scuba diver exposed to pressure variations. Pneumatocysts are rare and except for one case reported in a clavicular localization, are always found in subchondral bone of the iliac or sacral side of the sacroiliac joint. Undoubtedly, air fills an intraosseous node. We report here the first case of efficient treatment achieved by filling the cyst via percutaneous access under scopic control.     

The characteristics of the contact area of an endoprosthesis made from Ostek graphite-based material and of the mandibular bone fragment

Interactions between endoprostheses made of carbonic composition "Ostec" and bone tissue were studied after plastic repair of experimental vast defects in the mandible in 22 rabbits and 10 dogs over the course of 2 years. Histologic findings showed the formation of a layer of fibrous connective tissue 3 months after the operation and later; at some places the implant directly joins the rabbit bone, which frequently undergoes chondroid transformation. Microscopically, the structure of "Ostec" represents carbonic threads forming large bundles. By the 6th and 12th months of experiment connective tissue elements penetrate the fissures between the bundles and the perforation gaps of the endoprosthesis, forming bone-like and bone structures in them.     

Histological, clinical, and digital subtraction radiographic evaluation of repair of periodontal defects resulting from mechanical perforation of the chamber floor using ePTFE membranes

The aim of this study was to test the hypothesis that a biocompatible membrane, when placed between the gingiva and cortical bone in teeth with periodontal defects that occurred following mechanical endodontic perforation, would facilitate greater regeneration than in control sites not treated with guided tissue regeneration. One beagle dog with a healthy periodontium was used in the study. The maxillary right first and second molars and the mandibular left first and second molars acted as the experimental group in which furcation perforations were treated by guided tissue regeneration. The maxillary left and mandibular right first and second molars served as the controls in which furcation perforation lesions were only treated by open flap debridement. Clinical, histological, and standardized radiographic evaluation showed significant differences between the test and control groups. In addition, digital subtraction radiography revealed a gain in alveolar bone height and increased density at all experimental sites, and a loss at all control sites. Histological evaluation showed extensive regeneration of both alveolar bone and connective tissue at experimental sites, but none at control sites. The results of this study suggest that the use of guided tissue regeneration in furcation lesions produced by endodontic perforations will result in significant new bone and connective tissue attachment.     

Preimplant guided bone regeneration in the anterior maxilla

Guided bone regeneration is a clinical procedure aimed at promoting bone formation at sites where there is severe bone loss. The purpose of this article was to demonstrate reconstruction of deformations of the alveolar process resulting from traumatic injuries to maxillary incisor teeth by guided bone regeneration procedures followed by insertion of dental implants. In both cases, submembranous space-making was stabilized by human demineralized freeze-dried bone. Implant insertion at the sites of bone augmentation resulted in successful restorations. Histologic examination of biopsy samples from the submembranous hard tissue revealed particles of demineralized freeze-dried bone allografts partially surrounded by uninflamed connective tissue and by vital bone adjacent and adhered to the demineralized freeze-dried bone allograft particles.