Biomedical subjects

K Donath

Publications and source records attributed to K Donath.

At least 55 records · Page 3Linked to original sources

PubMed1998

Guided bone regeneration utilizing expanded polytetrafluoroethylene membranes in combination with submerged and nonsubmerged dental implants in beagle dogs.

Treatment of partial and total edentulism with submerged and nonsubmerged dental implants which follows the concept of osseointegration has become an accepted treatment modality. With compromised implant sites, practitioners have begun to combine one-stage implants with established techniques including guided bone regeneration. However, the clinical evaluation of this technique is limited. Therefore, the purpose of this study was to evaluate osseointegration and bone regeneration around nonsubmerged or submerged implants placed directly into surgically created osseous defects with or without expanded polytetrafluoroethylene (ePTFE) membranes. A total of 24 implants were placed in the mandibles of 4 beagle dogs and randomly assigned to 1 of 3 treatment groups. In group A, nonsubmerged implants were placed into osseous defects and treated with a poncho style ePTFE membrane. These membranes had a hole punched into the center and were slipped over the nonsubmerged implants. In group B, nonsubmerged implants were placed into osseous defects without an ePTFE membrane. In group C, submerged implants were placed into osseous defects and covered with an ePTFE membrane. Histometric measurements of each treatment group were made to determine percent bone gain or loss along the implant surface. Although a number of membrane removals occurred during the healing period, histological analysis indicated osseous ingrowth and osseointegration around nonsubmerged and submerged implants. An overall comparison of the treatment groups with ANOVA revealed that there were no significant differences between treatment groups, P > or = 0.05. However, when the data were stratified into sites which retained or lost the ePTFE membrane, the percent of bone regeneration was reduced in group A. Therefore, it may be recommended that nonsubmerged implants be placed with a submerged or "semi-submerged" protocol when utilized in conjunction with ePTFE membranes.

Animals↗

PubMed1998

BIO-OSS--a resorbable bone substitute?

BIO-OSS is an allergen-free bone substitute material of bovine origin, used to fill bone defects or to reconstruct ridge configurations. Seventy one patients (39 female, 32 male) received 126 BIO-OSS implantations. Some health parameters or habits were documented to eliminate possible risk factors of influence. The diameter of jaw defects filled with BIO-OSS was measured. There was a significant influence of the defect size on the healing result. In X-ray controls, BIO-OSS served to identify the surrounding native bone. The density of the BIO-OSS areas was higher than in control sites. These radiological results were supported by bone biopsies. Histologically, the permanency of the BIO-OSS was still recognizable after 6 years and longer. The ingrowth of newly formed bone in the BIO-OSS scaffold explained the increased density of the implanted regions. There were no clinical signs of BIO-OSS resorption. Therefore, we can assume that form corrections achieved by BIO-OSS insertions will last.

Absorption↗

PubMed1998

Histological findings in guided bone regeneration (GBR) around titanium dental implants with autogenous bone chips using a new resorbable membrane.

The aim of this study was to test the value of the new polydioxanone-membrane (PDS, Ethicon, Norderstedt, Germany) in combination with autogenous bone as a spacer for guided bone regeneration of denuded implant surfaces compared to simple augmentation. Forty implants were selected for 20 test cases (with membrane) and 20 control cases (without membrane) and were distributed randomly in 19 patients who were treated according to a standard protocol and examined. The defects were filled with autogenous bone chips, harvested interforaminally or locally, and were covered by the PDS membrane within the test group (control group: periosteum). The membranes were fixed with Memfix screws and cover screws. Seven membranes became exposed and were removed before reentry. Within the control group, three augments were sequestered. After 6 months, reentry was performed, the healing results were observed clinically, and biopsies were taken. The test group, including the seven cases with early removal of the membrane, showed that bone had filled in the defects in 95% of test cases, compared with 60% for the control group. The results of this study show that single augmentation of defects exceeding 9 mm2 is not sufficient. The membrane used in this investigation may be helpful for guided bone regeneration (GBR) at denuded screw thread sites in implant dentistry.

Adult↗

PubMed1998

Microlithiasis in parotid sialadenosis and chronic submandibular sialadenitis is related to the microenvironment: an ultrastructural and microanalytical investigation.

AIMS: Microlithiasis was investigated in parotid sialadenosis and chronic submandibular sialadenitis to determine if it relates to the glandular microenvironment as has been found experimentally. METHODS AND RESULTS: Semithin sections were stained by a mixture of methylene blue and Azure II followed by basic fuchsin, which stains calcified parts of microliths red and organic parts green, and ultrathin sections were examined electron microscopically and microanalytically. Microliths in sialadenosis were found in periacinar stroma, in which necrotic acinar cells were found, and in parenchyma, and consisted of consolidated organic material with little or no crystalline calcium. Microliths in sialadenitis were found in stroma, particularly around intercalary ducts, in lumina and in parenchyma, and contained much crystalline calcium. Macrophages enclosed some microliths. CONCLUSIONS: The paucity of calcium in microliths in sialadenosis and the abundance in sialadenitis relates to the glandular calcium. The periacinar distribution of microliths in sialadenosis possibly relates to formation in periacinar necrotic debris. The distribution of microliths in sialadenitis around intercalary ducts possibly relates to formation in matrix vesicles formed from atrophic parenchyma, and in lumina to formation in stagnant secretory material. Microliths appear to be scavenged by macrophages. Thus the experimental finding that salivary microlithiasis relates to the microenvironment pertaining in humans.

Calcinosis↗

PubMed1997

The congenital basal cell adenoma of salivary glands. Contribution to the differential diagnosis of congenital salivary gland tumours.

Congenital epithelial tumours of the salivary glands are very rare. The Salivary Gland Registry maintained in the Department of Pathology. University of Hamburg, contains only three cases among a total of 6,646 salivary gland tumours from the years 1965-1994. The three cases were classified as congenital basal cell adenoma, two of the parotid gland and one of the submandibular gland. Histologically, the three adenomas were similar in structure to the adult counterpart of basal cell adenoma with solid, trabecular or tubular (duct-like) patterns. In some cystic spaces of the duct-like structures PAS- and Astra blue-positive substances were secreted. On immunocytochemistry, the luminal duct-like cells showed membranous expression of cytokeratins 3, 5, 6, 7, 13 and 19. In the isomorphic basaloid cells of the solid and trabecular cell nests few cells expressed cytokeratin. On the outside of the solid cell nests there were smaller elongated myoepithelial-like cells, which expressed cytokeratin 14 and vimentin. Cytokeratins 1, 2, 4 and 18 were not expressed. The pattern of expression reflects the different stages of maturity of the tumour cells and is related to the development of the salivary glands until the end of the 3rd embryonal month with an arrest of further cell differentiation. No acinic cells, invasive growth, recurrence or metastases were observed. The differential diagnosis includes other congenital salivary gland tumours, such as hybrid basal cell adenoma-adenoid cystic carcinoma, sialoblastoma or embryoma, carcinoma, hamartoma and teratoma.

Adenoma↗

PubMed1997

[Sclerosing polycystic sialadenopathy. A rare non-tumorous disease].

Tumour-like lesions of the salivary glands are diseases which, in accordance with the new WHO classification of salivary gland tumours, can simulate a true tumour by swelling or induration of the salivary gland tissue. An additional rare entity, only recently not described in the new WHO classification, is "sclerosing polycystic sialadenopathy" (s.p.s.) which, especially in younger patients, results in nodular, incompletely encapsulated, tumour-like masses mainly of the parotid gland. Histologically, it is comparable to fibrocystic mastopathy and is characterized by distinct hyalinized, centrally accentuated sclerosing collageneous tissue with inclusion of cystically ectatic ducts and focal epithelial hyperplasia. In the hyperplastic ducts, trans-luminal bridges and cribriform patterns can develop, sometimes also apocrine secretion and eosinophilic globules. The s.p.s. must be distinguished mainly from cystadenoma, mucoepidermoid carcinoma and also from dysgenetic cystic parotid gland. Based on four of our own observations the differential diagnosis is analysed.

Adolescent↗

PubMed1997

Tumour-simulating squamous cell metaplasia (SCM) in necrotic areas of salivary gland tumours.

Squamous cell metaplasia (SCM) adjacent to necrotic areas of salivary gland tumours must be distinguished from other types of SCM (focal SCM in the excretory ducts of salivary glands; necrotizing sialometaplasia; focal SCM within salivary gland tumours) in respect to the tissue structure. Based on the high cellular proliferation, arcade- or cord-like pseudoneoplastic SCM develops with stellate extension in the surrounding tissue and focal inclusion of goblet cell metaplasia. This proliferative SCM resembles the cellular demarcation of radicular dental cysts. In the Salivary Gland Register 8 cases of tumor-simulating SCM could be analysed which clinically and morphologically were suspect of squamous cell or mucoepidermoid carcinoma. Five cases were localized in the parotid gland, 2 cases in the submandibular gland and 1 case in the palatinal glands. Tumour-simulating SCM was developed in pleomorphic adenomas (5 cases) and in multifocal adenomatous oncocytic hyperplasia (3 cases).

Adenoma, Pleomorphic↗

PubMed1997

Characteristics of the cancellous bone of edentulous mandibles.

Trabecular bone volume and trabecular connectivity (trabecular bone pattern factor) of edentulous mandibles were examined using undecalcified bone sections from the region of the 1st premolar to investigate atrophy-related changes in mandibular cancellous bone. The mean trabecular bone volume was 21.8% in female mandibles and 36.6% in male mandibles. The mean trabecular bone pattern factor was -0.22 mm-1 for female mandibles and -2.29 mm-1 for male mandibles. The difference between the sexes was statistically conspicuous for both parameters, but did not attain statistical significance. A notable fact was the extreme range of variation in both trabecular bone volume and trabecular connectedness. A difference of 65% between the highest and the lowest trabecular bone volumes measured in the present study (min, 7.6%; max, 73.6%, both male) reflects the possible variation in trabecular density of edentulous mandibles.

Aged↗

PubMed1997

[Differential diagnosis of tumorous space-occupying lesions of the parotid gland: angiolymphoid hyperplasia with eosinophilia and Kimura disease].

BACKGROUND: Subcutaneous mass lesions of the head and neck are common in angiolymphoid hyperplasia with eosinophilia (ALHE) as well as in Kimura's disease, most often in a periauricular location in young and middle aged adults. Often these benign angioproliferative lesions of unknown etiology will be misdiagnosed as parotid tumors although the majority are paraglandular. Whereas ill-defined lesions involving the parotid gland are frequently observed in Kimura's disease, only one case of intraparotid ALHE is reported in the literature. CASE REPORT: To this we add one further case: a 24-year-old man with a solid and well displaceable tumor of the left preauricular region. At ultrasound and intraoperatively we found a well demarcated tumor with high central vascularization surrounded by multiple networks of veins. One larger artery entered the lesion directly, visible as vascular structure on the cut surface. This blood vessel may have represented a vascular pattern (3 mm in diameter) that was identified as an artery by flow velocity measurement at duplex sonography. Histopathologically we saw the characteristic features of ALHE: numerous capillary proliferations showing prominent epithelioid endothelia cells with typical "hop nail" appearance, focal lympho-plasmacellular infiltrations and many eosinophils. The most conspicuous microscopic feature was a large thick-walled artery with total occlusions of the lumen that partially corresponded to duplex sonographic and macroscopic findings. CONCLUSION: In our opinion, this may be indicative of a primary arterial disorder with secondary vascular proliferation and chronic inflammation. The treatment of choice is local excision with a safe margin of healthy tissue, since insufficient removal can result in recurrence.

Adult↗

PubMed1997

The spectrum of giant cells in tumours of the salivary glands: an analysis of 11 cases.

In view of the different terminology for salivary gland tumours with giant cells, eleven cases were analysed by histopathology and immunocytochemistry. Four cases (three pleomorphic adenomas, one carcinosarcoma in a pleomorphic adenoma) were classified as having a foreign-body giant cell reaction, and five cases (two mucoepidermoid carcinomas, one acinic cell carcinoma, two carcinomas in pleomorphic adenomas) as having a sarcomatoid osteoclast-like giant cell reaction. In two further cases a giant cell tumour and a giant cell granuloma were associated with carcinomas in pleomorphic adenomas. All giant cells showed characteristic expression of CD68 as a typical marker for histiocytes and macrophages with their origin in mononuclear haematopoetic stem cells. There was no evidence for an epithelial origin of the giant cells because all those examined had a negative reaction to cytokeratin. Foreign-body cells were characterized by cytoplasmic vacuoles and irregularly dispersed nuclei. They showed a focally circumscribed reaction mostly outside the connective tissue pseudocapsule of the tumours. The sarcomatoid osteoclast-like giant cell reactions in carcinomas were distinctly intermingled with the carcinomatous patterns. In contrast, the associated osteoclast-like giant cell tumour was distinctly separate from the salivary gland tumour tissue and was composed of numerous larger osteoclast-like giant cells with a greater number of nuclei (more than 20); these giant cells were uniformly distributed throughout the tumour tissue. The giant cell granuloma was also separate from the carcinoma and was composed of nests of smaller, more irregularly distributed giant cells.

Adenoma, Pleomorphic↗

PubMed1996

Mucoepidermoid carcinoma of the salivary glands, Clinical data and follow-up of 52 cases.

Between 1965 and 1993, a total of 52 patients with mucoepidermoid carcinomas underwent surgical treatment. Their TNM stage at the time of initial diagnosis varied (T0:0, T1:24, T2: 19, T3: 2, T4: 7; NO: 46, N1: 4,N2: 2; MO:50, M1: 2). In the majority of patients (n=24) the history of symptoms ranged from more that 0.5 to 2 years without any specificity of features. Radical ablative surgery of the primary tumour is the therapy of choice. In patients suspected of having metastases of the regional lymph nodes, resection of the related lymphatic system has to be included in the therapeutic approach. The prognosis is excellent in patients with a localized manifestation. The patients who died for reasons of tumour metastasis had all been classified as having stage Iii to IV disease at the time of initial diagnosis. Distant metastases are rarely found even decades after surgical therapy. Long-term follow- up is recommended for patients with mucoepidermoid carcinomas.

Adolescent↗

PubMed1996

[Hyalinizing clear cell carcinoma of the salivary glands].

Many cell types of the salivary glands have clear cytoplasm. Causes of clear cytoplasmic quality in light microscopy are loss of organelles, storage of substances or fixation artefacts. Differential diagnosis of the different clear cell types requires special staining techniques, immunocytochemistry and electron microscopy. A new and distinct salivary gland neoplasm is hyalinizing clear cell carcinoma, which was not included in the second edition of the WHO Classification of Salivary Gland Tumors. Analysis of the collected cases of the Salivary Gland Register Hamburg and recent reports in the literature reveal that this carcinoma shows low-grade malignancy with localization usually in the minor salivary glands. Most cases occur in women. The pathohistology is characterized by solid or trabecular formations of polygonal clear cells which are surrounded by a broad hyalinized desmoplastic connective tissue stroma. The clear cells are mucin negative and express cytokeratin and EMA, in some cases also CEA, but not S-100 protein, actin or other markers of myoepithelial cells. Ultrastructural findings are undifferentiated duct cells with only few organelles and inclusion of glycogen granules. The differential diagnosis includes other clear cell tumours, especially epithelial-myoepithelial carcinoma and the clear cell variants of myoepithelial carcinoma and acinic cell or mucoepidermoid carcinoma.

Adenocarcinoma, Clear Cell↗

PubMed1996

Hybrid tumours of salivary glands. Definition and classification of five rare cases.

Hybrid tumours are very rare tumour entities which are composed of two different tumour entities, each of which conforms with an exactly defined tumour category. The tumour entities of a hybrid tumour are not separated but have an identical origin within the same topographical area. In contrast, biphasically differentiated tumours are a mixture of two cellular patterns with a corresponding term in the tumour classification. Examples of a biphasic differentiation are: basaloid-squamous carcinoma, adeno-squamous carcinoma or sarcomatoid carcinoma, and epithelial-myoepithelial carcinoma, mucoepidermoid carcinoma or adenoid cystic carcinoma. Hybrid tumours must also be distinguished from the multiple occurrence of salivary gland tumours which can develop syn- or metachronously. In the tissue samples of more than 6600 salivary gland tumours covered by the Salivary Gland Register (Institute of Pathology, University of Hamburg, Germany) only 5 cases of hybrid tumours were recorded between 1965 and 1994. This means less than 0.1% of all registered tumours. Case 1 was a very rare example of a hybrid adenoma with differentiation as a basal cell adenoma and a canalicular adenoma of the parotid gland. The similar cellular origin of both types of adenoma may be an explanation for its development in a hybrid adenoma. Case 2 is a hybrid tumour with a composition of basal cell adenoma and a glandular type of adenoid cystic carcinoma. In both types of tumours the two cell types (duct-lining cells and modified myoepithelial cells) have a similar histogenetic origin. Therefore, the development of the both cell types in a hybrid tumour with two trends of differentiation is possible. Case 3 represents a hybrid adenoma as a mixture of a Warthin tumour and a sebaceous adenoma. Although inclusions of sebaceous cells are observed in Warthin tumours, this hybrid tumour shows a composition of two different epithelial structures in a varied mixture. Case 4 is a very rare and unique hybrid carcinoma with two absolutely different components: acinic cell carcinoma and salivary duct carcinoma. The poor prognosis of this hybrid carcinoma is determined by the salivary duct carcinoma. Case 5 represents a hybrid carcinoma whose two components have a similar histogenetical basis: epithelial-myoepithelial carcinoma and a glandular type of adenoid cystic carcinoma. Both carcinomas are composed of variable proportions of ductlining cells and myoepithelial cells.

Aged↗

PubMed1996

Multiple tumours of the salivary glands--terminology and nomenclature.

Multiple tumours of the salivary glands are very rare and their combinations according to histological classification of the tumours, localisation and origin (origin in independent topographical areas or in the same tissue) are diverse. The following two categories can be distinguished: common occurrence of multiple salivary gland tumours with identical histology, or with different histology. In either group the tumours can be unilateral or bilateral, synchronous or metachronous. The most common multiple tumours with an identical histology are Warthin tumours and pleomorphic adenomas. Bilateral occurrence has been observed especially in oncocytomas, acinic cell carcinomas and basal cell adenomas. In the group of multiple tumours with differing histology, Warthin tumours and pleomorphic adenomas show a number of combinations with other adenomas or carcinomas of the salivary glands. Notable also is the simultaneous occurrence of salivary gland tumours with other oral tumours or extraglandular tumours, especially thyroid carcinomas and breast carcinomas. Multiple salivary gland tumours must be distinguished by nomenclature from tumours with biphasic differentiation and hybrid tumours. Tumours with biphasic differentiation are defined as regular, recurring mixtures of two cellular components in the same tumour and have a corresponding term in the tumour classification. Hybrid tumours are very rare and are composed of two different tumour entities within the same topographical area. Each of the tumour entities conforms with an exactly defined tumour category.

Adenolymphoma↗

PubMed1996

Comparison of healed tissues adjacent to submerged and non-submerged unloaded titanium dental implants. A histometric study in beagle dogs.

This study involved histometry of the healed tissues around submerged and nonsubmerged dental implants in beagle dogs. In a split-mouth design, 19 submerged and 19 nonsubmerged commercially pure titanium implants, titanium plasma-sprayed in the bone anchoring part and smooth in the transmucosal portion, were placed in the mandibles of 6 dogs. Oral hygiene was performed 3 times weekly. After 3 months of healing, transmucosal abutments were inserted in the submerged implants. Six weeks after second stage surgery, the dogs were sacrificed and specimens obtained and processed for histology and histometry. Using a light microscope and a digitizing pad, the distance from implant top to mucosa border (DIM), the extent of epithelial downgrowth (ED), the attachment level, (AL), the length of connective tissue contact (CTC) and the distance of the first coronal alveolar bone contact from the implant top (DIB) were measured at the mesial and distal aspects. Means +/- standard deviations for submerged and nonsubmerged implants were calculated, with the dog being the unit of measure. No statistically significant differences between submerged and nonsubmerged implants were found for DIM, CTC and DIB. However, significant differences were observed for ED and AL. This study in beagle dogs indicates that the apical extension of the peri-implant epithelium is significantly greater and the attachment level significantly lower adjacent to submerged implants with second-stage transmucosal abutments than in nonsubmerged, one-stage implants.

Alveolar Process↗

PubMed1996

A pilot study comparing screw-shaped implants. Surface analysis and histologic evaluation of bone healing.

The purpose of this study was to compare surface treatment and bone formation adjacent to 2 screw shaped implants of similar design manufactured by two different companies. The test implants were manufactured by SERF (Decines, France), while the controls were manufactured by Nobelpharma (Goteborg, Sweden). The surface of 3 standard 3.75 mm test and 3 standard 3.75 mm control implants were investigated by means of scanning electron microscopy (SEM), X-ray micro-analysis, electron spectroscopy for chemical analysis (ESCA) and surface topography analysis. There was a microscopic difference on the thread design (SEM). Test threads were flat at the edge, while controls appeared rounded at the edge of the threads. Tests and controls were made of commercially pure titanium, with a regular topography. Results of ESCA indicated that the carbon peak for SERF implants was slightly higher than for the Brånemark implants. 5 test and 5 control implants were installed into the epiphyseal head of the femur of 2 ewes using a standardized surgical technique. In order to stain the bone for histologic analysis, oxytetracycline injections were given 17 and 8 days before the animals were sacrificed. The animals were sacrificed 12 weeks after implant placement. Histomorphometric analysis indicated that there was an average bone to implant contact orf 68% for the test implants and 61% for the controls. There were no statistical differences between tests and controls. The preliminary results of this pilot study indicated that early bone healing for the 2 screw shaped implants investigated were similar.

Animals↗

PubMed1996

[What becomes of free septum cartilage transplants? Experimental studies of orthotopic cartilage transplantation].

BACKGROUND. Orthotopic septal cartilage transplants are grafted in numerous rhinosurgical operations. To ensure long-lasting success of surgery, preservation of the vitality of the grafted cartilage is imperative. Although many studies have been conducted on heterotopic cartilage transplants, no studies have been published on a follow-up of the course of orthotopic grafts. METHODS. We performed submucous septal resection in 33 rabbits and then regrafted the cartilage between the laminae of the mucous membrane. Microangiography was performed one, two, six and twelve weeks later and the cartilage was then examined histologically. Cartilage biopsies were performed on humans and compared with the experimental results. RESULTS. Integration of the cartilage presented a characteristic pattern: In the rabbit, the grafted cartilage had healed completely and had been stably integrated in three months' time. Reintegration with the orthotopic cartilage occurred by means of appositional reorganisation of cartilage originating from the inner perichondrium. Microangiography revealed that reintegration took place the faster, the shorter the distance between the cartilage cells and the vessels. We confirmed these experimental results also clinically by means of the cartilage biopsies in man.

Angiography↗

PubMed1996

Bone tissue reactions to demineralized freeze-dried bone in conjunction with e-PTFE barrier membranes in man.

Demineralized freeze-dried bone (DFDB) has been demonstrated to be osteoinductive in rodents, while no new bone formation has been reported at ectopic sites in goats, dogs and monkeys. In the present study, DFDB was used in connection with dental implant placement and expanded polytetrafluorethylene (e-PTFE) membranes. Histological examination showed that DFDB particles near the host bone underwent a partial remineralization, while DFDB distant from pre-existing bone was slowly resorbed and showed no remineralization, no osteoinduction, and no osteoconduction. This could be due either to the fact that the response to osteoinductive stimuli is lower in higher species, or to the fact that large quantities of DFDB are required to provide sufficient quantities of bone morphogenetic protein.

Alveolar Bone Loss↗