Mechanical behavior of quartz fiber reinforced epoxy resins for teeth restoration.

In this work composite materials, based on quartz fibers and epoxy resins, were employed with the aim to restore damaged teeth. The composite materials were chosen because they show biomechanical features very similar to that of the dentine, the main constituent of the tooth. Extracted teeth were rebuilt with two different restorative procedures: in the first, the composite material was pre-formed in a conical trunk shape abutment (PA) and then bonded to a fiber quartz post with a dental bonder. In the second rebuilt system the abutment was prepared by cross linking the resin on the fiber quartz post with a halogen lamp (CRA). The restored teeth were then mechanically tested and observed with a Scanning Electron Microscope (SEM) with the aim to study the interaction between the reconstructive materials. Wetting and roughness measurements were also carried out in order to study the interface adhesion between the post and the abutments. Characterization analysis evidenced that the CRA restorative procedure improves the adhesion between the substitutive materials and shows higher fracture strength than the PA ones. Anyway both the rebuilt systems are able to support the masticator load. An explanation of the interfacial post-abutment interaction phenomenon is discussed.

Polyamines in nickel-titanium archwire-induced gingivitis in adolescents.

BACKGROUND: Polyamines spermine, spermidine, and putrescine are involved in a number of inflammatory diseases, but their role in the development of gingivitis and periodontitis has not been fully investigated. The goal of this investigation was to study the levels and the variations of these amines, and the main enzymes related to their metabolism, during archwire orthodontic treatment, a condition which may induce gingivitis. METHODS: Sixty patients (age range: 11 to 27 years) were examined for gingivitis occurring during nickel-titanium (Ni-Ti) archwire orthodontic treatment. Plaque and gingival indexes (PI, GI) as well as salivary polyamine metabolism before the archwire insertion (T0) and at 3 (T1), 6 (T2), and 12 (T3) months of treatment were measured. RESULTS: In patients in the age range of 14 to 17 years, spermine and spermidine, but not putrescine contents, as well as ornithine-decarboxylase (ODC) and S-adenosylmethionine-decarboxylase (SAMDC) activities, significantly rose at 3 months after insertion, without any change in periodontal parameters, and further increased at 6 months reaching the maximum at 12 months. GI increased later, from 6 to 12 months, while PI did not significantly change. Spermidine/spermine-N1-acetyltransferase (SSAT) activity remained unchanged from T0 to T3. On the contrary, in patients whose age was 11 to 13 or over 18 years, no significant variations in polyamine metabolism and periododontal parameters were observed at any examination time. CONCLUSION: These data support the hypothesis that salivary polyamines might be earlier indicators of gingivitis than the gingival index score in adolescents wearing archwire appliances.

[An XPS and SEM study of the chemical-micromorphological characteristics of the dentin-resin adhesive interface. I]. / Studio XPS e SEM sulla caratterizzazione chimico-micromorfologica della interfaccia adesiva dentina-resina. Nota I.

In this preliminary note the author examined the chemical characterisation of dentin surfaces after treatment with an acid conditioner (nitric acid), using the XPS and Auger techniques, to evaluate whether micromorphological variations already reported by other authors are associated with changes of a chemical nature. The results of this study show an alteration of the superficial chemical component of dentin following treatment with the conditioner that would enable the realisation of closer binding with composite materials.

Protein-Signaled Guided Bone Regeneration Using Titanium Mesh and Rh-BMP2 in Oral Surgery: A Case Report Involving Left Mandibular Reconstruction after Tumor Resection.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is an osteoinductive protein approved for use in oral and maxillofacial defect reconstruction. Growth factors act as mediators of cellular growth on morphogenesis and mythogenesis phases. Utilized as recombinant proteins, these growth factors need the presence of local target cells capable of obtaining the required results. This cell population may be present at the wound site or added to scaffolding material before implantation at the surgical site.The aim of this study is to evaluate the clinical and radiographic results of a reported case with a large bone defect, treated with an absorbable collagen sponge, rhBMP-2 and a titanium plate and mesh. The Authors want to report a case which shows the resulting effectiveness of the rhBMP2 action regarding a large, mandibular defect reconstruction. This case also shows how the removal of a rare tumor such as a ghost cell tumor of the jaw may be treated without harvesting bone from another body site. A quick diagnosis of the lesions is important in order to perform the most suitable treatment. The Authors also underline the clinical and histological steps to insure the correct treatment is carried out to solve the case.Moreover, from results obtained from this case, it is possible to highlight several clinical benefits for the patient by adding rhBMP-2 to the common allograft to not only have alveolar reconstruction defects and sinus floor augmentation, but also to have alveolar cleft reconstruction and to treat segmental defects.

Patients with bisphosphonates-associated osteonecrosis of the jaw have reduced circulating endothelial cells.

Osteonecrosis of the jaws (ONJ) associated with the use of bisphosphonates is a newly described entity. To elucidate the mechanism leading to ONJ and to test the hypothesis that in patients with ONJ the bisphosphonates may interfere with endothelial cell proliferation, using flow cytometric analysis we evaluated the number of circulating endothelial progenitor cells (EPCs) and circulating endothelial cells (CECs) in eight patients with bisphosphonate treatment and osteonecrosis, eight multiple myeloma (MM) patients with bisphosphonates treatment without ONJ and five normal subjects. MM patients showed an increase of CD34+ cells with respect the control subjects and ONJ subjects. EPCs and CECs were higher in MM patients compared to controls and ONJ patients. ONJ patients showed a decrease of EPCs compared to control subjects while CECs were similar to the controls group. Our results seem to show the possibility that bisphosphonates could have a antiangiogenic effect and a suppressive effect on CECs of patients with ONJ.

[Acrylic resin-silicone elastomer interface with the polymeric interpenetration technique (P.I.T.)]. / L'interfaccia resina acrilica--gomma siliconica con tecnica dell'interpenetrazione polimerica (I.P.N.).

The Author has carried out a microphotographic analysis on samples bulk in acrylic resin with flexible edges using the interpenetrating polymeric system network suggested by Nishijama and Coll. The electronic scanning on the interfaces siliconic resin IPN and acrylic resin-IPN showed cracks and grooves that report the imperfect adhesion of polymeric materials.

[Use of the Maryland bridge in periodontology]. / Applicazione del Maryland bridge in parodontologia.

The authors have reported the investigations about the Maryland Bridge and its importance in periodontology. The Authors have suggested the clinical application of this kind of prosthesis and the Authors have reported about two clinical cases that have had first a periodontal treatment then a Maryland Bridge prosthesis.

[Use of G.I.C. as a cavity liner. Clinical experience]. / L'uso del C.V.I. come sottofondo di cavit': experienze cliniche.

The authors have examined the effects of the C.V.I. used as liners in the V Black classes in fillings made by restorative material on the right-hand dental maxillary arch of five patients, comparing them to the left-hand dental maxillary arch on some subjects affected by the some lesions and filled with the some procedure but using as liner a calcium hydroxide material submitting the all treated teeth to a sensitivity tests. On the basis of such clinical experience the Authors conclude that the use of the C.V.I. as liner shows, compared to the calcium hydroxide, the characteristic to be chemically bonded to the dentin and mechanically through the eching to the composite restorative material as well as the bio-mimetic characteristic property towards the dentin.

[Use of silanes as bonding intermediates in alloy-adhesive-alloy systems]. / Contributo clinico sull'impiego dei silani come intermediatori di adesione nel sistema lega-adesivo-lega.

The Authors suggest on original appliance of the adhesive bridge on metallic surface of pre-existent fixed prosthesis by means of silanes. In two clinical cases the silanes make it possible to apply on adhesive bridge without damage for contiguous theets and to resolve difficult prosthetic problems with good outcome.

[The effect of plasma nitriding on tungsten burs]. / Ricerche sperimentali sugli effetti della nitrurazione in plasma di frese al tungsteno.

The authors have experimented the nitriding's effects on some cilindrical burs carbide utilized in dentistry after disamination on the applications methodics on plasma nitriding in neurosurgery, orthopedic surgery and in odontotherapy. This reacherys point out that nitriding plasma a durings increase and cutis greater capacity establish.

Determination of polyamines in human saliva by high-performance liquid chromatography with fluorescence detection.

A high-performance liquid chromatographic method for the determination of polyamines (spermine, spermidine and putrescine) in human saliva was developed. This method is based on pre-column derivatization with o-phthaldialdehyde (OPA). The derivatives were separated on a Nucleosil ODS column (250x4.6 mm I.D.; 5 microm). The gradient elution was performed with two mobile phases A (water) and B (methanol) at a flow rate of 0.8 ml/min. The column eluate was monitored by fluorescence detection (excitation, 360 nm; emission, 510 nm). The within- and between-assay coefficients of variation for all the compounds were below 5%. The detection limits for spermine, spermidine and putrescine were 0.04, 0.05 and 0.06 nmol/ml, respectively. The recovery was greater than 90%. Our analytical technique requires neither preliminary extraction with an organic solvent, nor long multi-step procedures. For saliva samples, this is a simple, rapid and highly reproducible method that can be easily applied to the routine determination of salivary polyamines, whose levels increase early in several pathological conditions.

Age-related salivary polyamine increase in adolescents wearing orthodontic Ni-Ti archwires.

Until now information about the influence of puberty on gingival tissue responses to Ni-Ti alloy haven't been available. Since our previous researches have demonstrated that Ni-Ti appliances have an influence on hyperplastic gingivopathy and data has pointed out a possible hormonal influence on the susceptibility of gingival tissue to mechanical stress, we have attempted to study the relationship between fertility hormones and the periodontal response to Ni-Ti appliances. Three groups, ranging from 6 to 17 years old, were tested for salivary polyamine concentrations and for fertility hormone levels 12 months after Ni-Ti application. Results obtained from Pearson's correlation coefficient between polyamine and sexual hormone concentrations, as well as gingival and plaque indexes, suggest that the adolescent gingival tissue undergoes an hyperplastic process after long-term use of Ni-Ti appliances in relation to the puberty age-restricted peak of fertility hormones.