D. Hrusak

Evaluating the osseointegration of nanostructured titanium implants in animal models: Current experimental methods and perspectives (Review)

The aim of this paper is to review the experimental methods currently being used to evaluate the osseointegration of nanostructured titanium implants using animal models. The material modifications are linked to the biocompatibility of various types of oral implants, such as laser-treated, acid-etched, plasma-coated, and sand-blasted surface modifications. The types of implants are reviewed according to their implantation site (endoosseous, subperiosteal, and transosseous implants). The animal species and target bones used in experimental implantology are carefully compared in terms of the ratio of compact to spongy bone. The surgical technique in animal experiments is briefly described, and all phases of the histological evaluation of osseointegration are described in detail, including harvesting tissue samples, processing undemineralized ground sections, and qualitative and quantitative histological assessment of the bone-implant interface. The results of histological staining methods used in implantology are illustrated and compared. A standardized and reproducible technique for stereological quantification of bone-implant contact is proposed and demonstrated. In conclusion, histological evaluation of the experimental osseointegration of dental implants requires careful selection of the experimental animals, bones, and implantation sites. It is also advisable to use larger animal models and older animals with a slower growth rate rather than small or growing experimental animals. Bones with a similar ratio of compact to spongy bone, such as the human maxilla and mandible, are preferred. A number of practical recommendations for the experimental procedures, harvesting of samples, tissue processing, and quantitative histological evaluations are provided.

Langerhans cell histiocytosis in childhood – Review, symptoms in the oral cavity, differential diagnosis and report of two cases

BACKGROUND Langerhans cell histiocytosis is a rare disease characterized by monoclonal proliferation and migration of special dendritic cells. This disease primarily affects bones, but occurs less frequently in other organ systems or may manifest as a multisystem disease. CASE REPORTS Extraoral and intraoral symptoms of Langerhans cell histiocytosis are described in a 13-month-old female and a 5-month-old male infant. Dermatitis was found on the scalp, abdomen, flexures and in intertrigineous areas in both patients. The intraoral examination of the 13-month-old infant showed premature eruption of all maxillary deciduous molars, loosening and significant damage of periodontal tissues (gingivitis with bleeding, swelling of palatal mucosa, periodontal pockets) resembling severe periodontitis. In the oral cavity of the 5-month-old predentate infant bilateral swellings of maxillary alveolar mucosa with deep ulcerations were seen. The oral and skin symptoms in both infants were indications for biopsy. Langerhans cell histiocytosis was confirmed histologically and immunohistochemically. CONCLUSION Oral findings in Langerhans cell histiocytosis may be the only clinical symptom of the disease; therefore the role of dentists in establishing diagnosis is very important.

Hypothyroidism after radiotherapy of head and neck cancer

AIM Hypothyroidism is not commonly considered as a complication of radiotherapy to the head and neck region. The purpose of this retrospective study was to determine the frequency of thyroid dysfunction in patients after radiotherapy, to compare thyroid hormone levels in irradiated patients with Control group and to predict development of thyroid hypofunction in time. MATERIAL AND METHOD Thyroid function was measured by means of thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodthyronine (FT3) in 43 patients who had nonthyroid head-neck carcinomas treated by radiotherapy or radiotherapy in combination with other modalities. These data were compared with hormone levels of 40 Control group patients treated solely by surgery. RESULTS Hypothyroidism was found in 35% of irradiated patients. In comparison with Control group there were significant differences between TSH and FT4 levels, difference between FT3 levels was insignificant. A correlation between hormone levels and follow-up was detected. CONCLUSION Our results indicate that hypothyroidism is a frequent late side effect of radiotherapy to head and neck. Lifelong monitoring of thyroid function appears to be justified when radiotherapy is a part of treatment protocol.

Comparison of fibroblast and osteoblast response to cultivation on titanium implants with different grain sizes

The in vitro response of human fibroblast cell line HFL1 and human osteoblast cell line hFOB 1.19 on nanostructured titanium with different grain sizes has been compared in the present study. Used samples of titanium produced by equal channel angular (ECA) pressing have grain sizes of 160 nm, 280 nm, and 2400 nm with cross- and longitudinal sections. Similar cellular behaviour was observed on all studied biomaterials. There were significant differences related to the initial phase of attachment, but not in proliferation. Furthermore, the results indicate that osteoblasts grow best on material with grain size of 160nm with a longitudinal section in comparison with other examined materials. Therefore, this material could be recommended for further evaluation with respect to osseointegration in vivo.

Proliferation of Osteoblasts on Laser-Modified Nanostructured Titanium Surfaces

Nanostructured titanium has become a useful material for biomedical applications such as dental implants. Certain surface properties (grain size, roughness, wettability) are highly expected to promote cell adhesion and osseointegration. The aim of this study was to compare the biocompatibilities of several titanium materials using human osteoblast cell line hFOB 1.19. Eight different types of specimens were examined: machined commercially pure grade 2 (cpTi2) and 4 (cpTi4) titanium, nanostructured titanium of the same grades (nTi2, nTi4), and corresponding specimens with laser-treated surfaces (cpTi2L, cpTi4L, nTi2L, nTi4L). Their surface topography was evaluated by means of scanning electron microscopy. Surface roughness was measured using a mechanical contact profilometer. Specimens with laser-treated surfaces had significantly higher surface roughness. Wettability was measured by the drop contact angle method. Nanostructured samples had significantly higher wettability. Cell proliferation after 48 hours from plating was assessed by viability and proliferation assay. The highest proliferation of osteoblasts was found in nTi4 specimens. The analysis of cell proliferation revealed a difference between machined and laser-treated specimens. The mean proliferation was lower on the laser-treated titanium materials. Although plain laser treatment increases surface roughness and wettability, it does not seem to lead to improved biocompatibility.