Endosseous cylinder implants in severely atrophic mandibles.

A retrospective study was completed to assess the success rate of endosseous cylinder implants placed in mandibles that were 10 mm or less in maximum anterior height as measured from lateral cephalometric radiographs. Only implants that were located anteriorly between the mental foramina and loaded prosthetically for a minimum of 1 year were studied. Twenty-eight patients with a total of 130 Nobelpharma implants (forty-six 7 mm and eighty-four 10 mm) were included. The fixtures were evaluated following standard clinical criteria for success established for implants of this type. A total of 8 (two 7 mm and six 10 mm) of 130 implants failed, yielding an overall success rate of 94%. Major complications encountered included a complete mandibular fracture, a partial mandibular fracture, and a temporary bilateral mental nerve hypoesthesia.     

Amalgam and composite restorations: reasons for placement and replacement

A survey, in order to ascertain the reasons for placement and replacement of amalgam and composite restorations was made with the consent of the Italian Academy of Conservative Dentistry. 62 dentists answered the questionnaire, analysing their daily restorative work for two weeks: a total of 2,960 restorations were scored. The results show a prevalence of the primary caries over the replacements, and a prevalence of the secondary caries over the remaining reasons for replacement. Both data possibly mean the need for a more preventive approach to dental caries in Italy, even if the results fit fairly well into the values of the international research.     

Quality of marginal adaptation evaluation of posterior composites in clinical trials

The evaluation of margins of restorations in clinical trials relies on the subjective assessment of evaluators, with no instrument having been developed, let alone validated, to assist in the process. The purpose of the present study was to assess the quality of evaluations of marginal adaptation by analyzing the distribution of marginal steps rated according to clinical criteria. Replicas of 435 restorations, the marginal qualities of which had been evaluated according to modified USPHS criteria, were randomly selected from the Occlusin multi-center clinical trial program. The marginal step height in the most deteriorated area of each restoration was measured by means of a digital step-height instrument. An overlap between the steps in the restorations with A (Alfa; replacement unnecessary) and B (Bravo; replacement questionable) ratings was found to be in the range of 101 microm to 321 microm. When the steps with a height greater or less than one standard deviation of the mean were excluded, the overlap was reduced to a range of 168 micro m to 173 microm. This finding indicates a marginal height boundary between A and B ratings for marginal adaptation of 170 +/- 3 microm.     

Characterization of the immunologic responses to human in vivo acquired enamel pellicle as a novel means to investigate its composition

Human acquired enamel pellicle is formed by molecules selectively adsorbed onto tooth surfaces. The present work describes the use of monoclonal antibody (mAb) technology as a novel approach to identify micro amounts of components present in pellicle. MAbs were obtained with reactivities against statherin, histatin, mucous glycoprotein 1(MGI), albumin, amylase and human immunoglobulins (Igs), indicating that these are pellicle components, which was further confirmed by immunoblotting. No mAbs against proline-rich proteins (PRPs), lysozyme, mucous glycoprotein 2 (MG2), carbonic anhydrase, lactoferrin or peroxidase were obtained, suggesting that these components are absent, present in low amounts, or exhibit low antigenicity. Further characterization of the binding epitopes of some of th e obtained anti-MGO, anti-statherin and anti-histatin mAbs were carried out and the biological relevance is discussed. The results open up the possibility that immunization with human pellicle and mAbs production can be employed to identify hitherto unknown constituents of pellicle.     

Incidence of penetration of a blood vessel during inferior alveolar nerve block

Aspiration of the syringe after the needle had been placed in position for an inferior alveolar nerve block (but before the anaesthetic solution was injected) in 250 patients showed that the tip of the needle was in a blood vessel in 49 (20%). Aspiration of blood was significantly more common in patients aged 9-19 years than in all others (P=0.04).     

Inhibitory effect of synthetic histatin 5 on leukotoxin from Actinobacillus actinomycetemcomitans

Actinobacillus actinomycetemcomitans is a gram-negative bacterium strongly implicated in the pathogenesis of juvenile periodontitis. This periodontal pathogen synthesizes a leukotoxin that destroys human polymorphonuclear leukocytes (PMNs), and this toxin is thought to be responsible for the virulence of A. actinomycetemcomitans. It was therefore of interest to assess whether major virulence factors of periodontal pathogens were neutralized by salivary components. This study focuses on the effect of histatins, components of the nonimmune oral defense system, on leukotoxin activity. Leukotoxin was extracted with polymyxin B from freshly grown anaerobic cultures of A. actinomycetemcomitans strain Y4. PMNs isolated from blood of healthy human volunteers were incubated in a cytotoxicity assay containing PMNs (10(7) cells/ml) and leukotoxin preparation (0-500 microg/ml) in Hanks' balanced salt solution at 37 degrees C for 0-120 min with or without synthetic histatin 5 (0-500 microM). Cytotoxicity was measured by release of lactate dehydrogenase (LDH) at different time intervals. Histatin 5 neutralized the toxic effect of the leukotoxin preparation in a concentration-dependent manner, with an IC(50) value of 150 microM. When PMNs were preincubated with histatin 5 (300 microM), washed and subsequently exposed to leukotoxin, no protective effect was observed. This observation suggests a mechanism of inhibition whereby histatin 5 either directly neutralizes the leukotoxin or interferes with the leukotoxin-PMN interaction. The inhibitory effect of histatin 5 on leukotoxic activity may suggest a new biological function of histatins in the oral cavity as a naturally occurring secondary antibiotic.