Surface scratch assessment of titanium implant abutments and cementum following instrumentation with metal curettes.

OBJECTIVES: This study was conducted to compare the surface scratch resistance of titanium implant abutments and cementum to evaluate the impact of scaling with metal curettes on both surfaces. MATERIALS AND METHODS: A standard in vitro force of 14 N was used to assess the scratch width and depth created by curettes on extracted human tooth roots and titanium implant abutments. Scratch width and depth were analysed using a stereomicroscope and non-contact surface profilometry. RESULTS: The mean force applied during test scaling procedures by experienced volunteer operators was 14 N. Mechanical scaling using this force in vitro of cementum produced a mean scratch width of 59.4 ± 1.9 µm, N = 20, and scratch depth of 0.86 ± 0.03 µm, N = 20, compared to the titanium abutments' mean scratch width of 30.8 ± 1.9 µm, N = 6, and scratch depth of 0.34 ± 0.02 µm, N = 6. These differences were statistically significant (P < 0.05). CONCLUSIONS: Although there a number of factors in the clinical situation which are not easily reproducible in vitro, this proof-of-principle in vitro study is the first to confirm quantitatively that titanium abutments had a significantly greater scratch resistance than cementum when metal curettes were used on these surfaces. This information should be considered, especially if there is a preferred choice of metal instruments for effective dental prophylactic procedures for the maintenance of titanium dental implants. CLINICAL RELEVANCE: Clinical dogma suggests that titanium implant abutment surfaces should not be instrumented with metal instruments due to scratching of the surface. However, since cementum is softer than titanium, the logic of this tenet seems flawed. This study demonstrated for the first time that titanium abutments undergo less scratch damage during scaling with metal curettes than does cementum. Metal curettes may be used on titanium abutments with as much confidence as for root planing on natural teeth.

Sleep disorders and driving licence: the current Italian legislation and medico-legal issues.

Road traffic accidents (RTA) are a serious issue in all industrialized countries and have dramatic social and healthcare-related implications. Fatigue (sleepiness) is the principal identifiable and preventable cause of road traffic accidents. Obstructive sleep apnoea syndrome (OSAS) and narcolepsy are two of the leading causes of excessive daytime sleepiness. In this article, the authors analyze the current Italian legislation regarding driving licence issuance and fitness to drive, in order to evaluate the potential implications of sleep disorders, particularly OSAS and narcolepsy. In European Legislation and in Italy, OSAS and narcolepsy are not included among the illnesses or invalidating conditions that limit the fitness to drive for driving licence issuance purposes. In fact, they are not included in the Annex III of the European Council Directive 91/439/EEC of the 29th of July 1991 on driving licences. Some Countries of the European Union (Belgium, France, Finland, Great Britain, the Netherlands, Spain and Sweden) had implemented the 91/439/EEC Directive with national restrictions on driving licence issuance policies in case of OSAS and narcolepsy. Given the well-established scientific evidence available, in Italy, the lack of legislation regulating the assessment of the psychophysical requisites for the issuance and renewal of driving licences of individuals affected by sleep disorders seems extremely worrying. Furthermore, the current lack of legal obligation in Italy for healthcare facilities to disclose such diagnoses to the organs responsible for issuing driving licences (such as the Motorizzazione Civile - the Department of motor vehicles) remains the subject of heated debate.

Assessment of the regenerative potential of allogeneic periodontal ligament stem cells in a rodent periodontal defect model.

BACKGROUND AND OBJECTIVE: The complex microenvironment of the periodontal wound creates many challenges associated with multitissue regeneration of periodontal lesions. Recent characterization of mesenchymal stem cell-like populations residing in periodontal ligament tissues has shown that these cells exhibit features of postnatal stem cells. Despite these advances, a lack of consistency in design of preclinical studies and a limited study of allogeneic transplantation applications has restricted our understanding of their clinical utility in the treatment of periodontal disease. The aim of this study was to assess the regenerative potential of allogeneic periodontal ligament stem cells (PDLSCs) in a rat periodontal fenestration defect mode and to identify an optimal end time-point suitable for quantitative assessment of tissue regeneration. MATERIAL AND METHODS: Periodontal fenestration defects, created in Sprague Dawley rats, were treated with allogeneic PDLSCs seeded onto Gelfoam(®) (Absorbable gelatin sponge; Pharmacia Corporation, Kalamazoo, MI, USA) or with Gelfoam(®) alone, or remained untreated. Experimental rats were killed at 7, 14, 21 or 28 d after surgery and the tissues were processed for immunohistochemical and histomorphometric examination. RESULTS: Defects treated with PDLSCs showed significantly greater percentage bone fill and length of new bone bridge compared with the untreated group or the group treated with Gelfoam(®) alone on days 14 and 21. Similarly, a statistically significant difference was achieved within specimens retrieved on day 21 for analysis of regeneration of cementum/periodontal ligament (PDL)-like structures. CONCLUSION: The present investigation shows that allogeneic PDLSCs have a marked ability to repair periodontal defects by forming bone, PDL and cementum-like tissue in vivo. The results suggest that treatment periods of 14 and 21 d are optimal end time-points for quantitative assessment of periodontal regeneration within the rodent fenestration-defect model utilized in the present study.

Assessment of the main pancreatic duct using computed tomography with multiplanar reconstructions.

UNLABELLED: The aim of this study was to assess the morphology of the main pancreatic duct (MPD) using multiplanar reconstructions and to compare this with the morphology of the MPD of anatomic subjects. MATERIALS AND METHODS: The morphology of the MPD was studied by means of multiplanar reconstructions obtained on the one hand from thin tomodensitometric slices and on the other hand from the dissection of anatomic subjects. This study involved 15 subjects in each group. RESULTS: Full multiplanar reconstruction was obtained in 13 cases. In 2 cases, the isthmus did not appear in the reconstructions. The morphology of the MPD was similar in both groups. The length of the MPD was identical at the head and isthmus of the pancreas in both groups but was greater in the dissection group than in the reconstruction group in the body and tail areas of the pancreas. The diameter of the MPD was greater at the head of the pancreas in the dissection group and was identical in both groups for the other segments of the MPD. CONCLUSIONS: Multiplanar tomodensitometric reconstruction of the main pancreatic duct is feasible. This new technique, currently under evaluation, could allow the study of canalar pathologies of the pancreas through tomodensitometry.

Assessment of delta virus infection in Venezuelan high-risk population for hepatitis B virus.

HDV infectivity particularly related to sexual activity has been difficult to establish. We investigated the prevalence of HDV in a high risk urban male population currently evaluated for HIV infection. Fourth-eight homosexual or bisexual men (96% positive for HIV) being routinely followed in the outpatient clinic, 40 sera obtained randomly from male homosexuals and 24 HBsAg carriers were examined by ELISA and Western Blot. HDV RNA was assessed by slot-blot after hybridization with cDNA probe from a recombinant plasmid (pS-1). [None of the 48 male subjects or from a recombinant plasmid (pS-1).] None of the 48 male subjects or from the randomly selected homosexuals tested positive for anti-HDV. HDV RNA searched in a selected group of sera from either high risk population or from HBsAg carriers proved also to be negative. We suggest that factors other than HBV chronic bearing and/or sexual promiscuity should be associated with HDV spread.