[Osteo-conductive materials: animal experiments and instrumental analysis II]

BACKGROUND

In daily dental surgery practice, when it is not possible to obtain-enough autogenous bone graft to fill bone defects, bone substitutes can be useful for bone regeneration.

MATERIALS AND METHODS

After a preliminary microscopic examination of histologic samples obtained from semithin sections of the tibias of rats showing no major differences in the results both for the single material and implant time, further studies on five different osteoconductive materials used in oral clinical practice were carried out with microradiography, SEM and X-ray microanalysis. In experimental animals (rats) bone defects 3 mm large were surgically induced in both tibias: one of the defects was filled by bone substitutes and on the other side the bone defect healed naturally.

RESULTS AND CONCLUSIONS

The findings obtained were studied in depth, and allowed to conclude that the materials tested are suitable for the purpose for which they are marketed. Non-demineralized bovine bone showed the best results with a high degree of osteointegration. However, the results also show that not all the materials tested offer healing advantages over controls.

Endoarticular loose bodies and calcifications of the disk of the temporomandibular joint: morphological features and chemical composition

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radiopaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in circumscribed areas of the endoarticular loose bodies. The chemical-compositional analysis showed that the loose bodies were composed of calcite (CaCO3). The results of this investigation, along with the clinical history of the patients, allow us to formulate some hypotheses regarding the etiopathogenesis of these structural anomalies. The endodiscal calcifications could be the result of a chronic inflammatory process that produces displastic alterations of the articular disk. Moreover, an acute inflammatory process with modifications in the mechanisms of the synovial fluid turnover seems to be the event that leads to the formation of endoarticular loose bodies.

Collagen fiber arrangement in temporo-mandibular joint (TMJ) disks from human subjects with functional diseases. Scanning electron microscopy investigations

Twelve articular disks from patients with temporo-mandibular joint (TMJ) arthropathy were studied and compared with two normal disks. Scanning electron microscopy (SEM) examination of the surfaces and of longitudinal and cross-sections of the disks allowed the observation of the arrangement of the collagen fiber component in different parts of the disk. The superficial part of the articular disks appears to be formed by rather compact fibers. The internal portion is usually formed by bundles of collagen fibers in sheets, alternating with isolated fibers arranged in a parallel or irregular way. In some samples, blood vessels were observed. Our investigations suggested that the appearance of vascularization is the first remarkable histological change that can be observed in functionally abnormal articular disks.

Late taste disorders in bone marrow transplantation: clinical evaluation with taste solutions in autologous and allogeneic bone marrow recipients

The aim of this work was to determine the type and the significance of taste disorders in allogeneic bone marrow transplanted patients. In a retrospective study the taste threshold of a cohort of 15 allogeneic bone marrow transplanted patients, 4-51 months after transplantation (mean: 30.6 +/- 15.8), was compared to the taste threshold of 8 autologous bone marrow recipients, 4-48 months after transplantation (mean: 24.12 +/- 12.18), and to the taste threshold of a group of 20 consecutive normal subjects. Allogeneic bone marrow transplanted patients showed a significant hypogeusia for salt (Pearson's chi square p = 0.0002; Yates' correction p = 0.0007) and sour (Pearson's chi square p = 0.001; Yates' correction p = 0.008). No significant variations were observed for sweet and bitter. Autologous bone marrow recipients did not show any significant variation of taste acuity for sweet, salt or sour; a constant reduction of the taste threshold for bitter was observed, but the values were not significantly different from normal (Pearson's chi square p = 0.47; Yates' correction p = 0.83). So, late and selective taste disorders are observed in allogeneic bone marrow transplanted patients. Since the severity of the disorders is not strictly related to the severity of chronic oral G.V.H.D., taste analysis could discover the slightest, clinically undetectable cases of chronic oral G.V.H.D. The mechanism of immune aggression on the sensorial taste cells is poorly understood. Further trials are needed to define variations of taste acuity not only after allogeneic bone marrow transplantation, but also in systemic immune diseases.

[Supernumerary teeth in the deciduous dentition]

The Authors presented sovrannumeraries (S) teeth in primary dentition, and the pedodontic, surgical and orthodontic problems. Semeiotics signs, and X Ray suggested, are described. All the types of S. teeth are showed: supplementaries, conoides, tuberculates and infundibuliformes. For every type characteristics, problems and surgical timing are described. Tuberculates and infundibuliformes teeth are the most dangerous for the permanent teeth interrupted: eruption delay, dilacerations, impactions, fusion, follicles, diseases, are reported. The direction of the growth of S. teeth must be analyzed. If the direction is external the timing of surgery is very important. Finally the Authors emphasized the role of cooperation of pedodontist, with oral surgeon and orthodontist for to obtain good results.

[Ectodermal dysplasia. Clinical case]

A case of ectodermal dysplasia with anodontia, and severe hypotrichosis is described. Clinical aspects and differential diagnosis with Huth-chinson-Gildorf syndrome are also discussed.

[Applications of the ETCH technic and orthodontic brackets in some clinical cases]

The Authors shawed how the sealants having a resin base that can establish with tooth surfaces treated with acid, a sound connection among these and orthodontic brackets, originally used in orthodontic treatment, can also be used for fixation of fractures. The case described concern seven patients with a fracture of maxillaries. It was demonstrated that such a procedure was easy to execute for the operator and did not give any trouble to the patient. The results obtained were satisfactory.