Removal of Porcelain Veneers Aided by a Fluorescing Luting Cement

Purpose: Porcelain veneers are a safe and effective treatment modality for selected teeth that have poor esthetics. However, removal of porcelain veneers that have failed may be time‐consuming and involve considerable removal of sound tooth structure adjacent to the veneer. The aim of this study was to evaluate a novel method of porcelain laminate veneer removal by incorporating a fluorescent dye into the luting cement that allows the practitioner to visualize the cement on the tooth and remove the veneer without causing residual damage to the adjacent tooth substance. Materials and Methods: Porcelain veneers were luted on extracted teeth with a luting cement modified with a fluorescing agent. Faculty teaching staff and final year dental undergraduates were asked to remove the veneers with the aid of a curing light to render the luting cement visible by fluorescing. They were then asked to compare the removal of comparable veneers without this visual aid and to complete a standard questionnaire. The depth of cure of the conventional and modified cements was measured using a penetrometer. Results: Results of the questionnaire indicated that the operators found removing the veneer cemented with the modified (fluorescing) cement considerably easier than removing the veneer cemented with the conventional cement. Microscopy indicated that more damage was caused to the underlying tooth during removal of conventionally cemented veneers. The incorporation of the dye into the cement reduced the depth of cure from 4.238 mm (SD = 0.025) to 3.761 mm (SD = 0.096). CLINICAL SIGNIFICANCE The fluorescent cement was considered to be superior to conventional cements in its ease of visibility, and as a consequence, veneers cemented with the fluorescing cement are easier to remove. The fluorescing dye significantly reduced the depth of cure, but this may not be clinically significant, because of the small thickness of cement employed when luting adhesive restorations. The use of such fluorescing materials may not be restricted to a luting cement for veneers but may also be incorporated into bases and lining materials so they can be visualized on removal of tooth‐colored restorations, to prevent further tooth destruction.     

Role of parvovirus B19 infection in childhood idiopathic thrombocytopenic purpura

Although parvovirus B19 exhibits a strong tissue-tropism for erythroid progenitor cells leading to anaemia, several case reports indicate that parvovirus B19 infection may also cause the development of thrombocytopenia. Despite recent studies, the frequency and clinical relevance of this association have remained questionable. Consequently, and in view of the paucity of evidence regarding a viral aetiology for idiopathic thrombocytopenic purpura (ITP), we examined the role of parvovirus B19 in 47 children with newly diagnosed ITP. Specific viral DNA indicating a current or recent parvovirus B19 infection was demonstrated in 6 of 47 patients (13%) employing the polymerase chain reaction technique. Our study suggests that children with ITP and associated parvovirus B19 infection are characterized by acute onset of profound thrombocytopenia. Among the parvovirus B19 positive children, duration of disease was brief in three children treated with immunoglobulin but chronic in the remaining three patients given high-dose steroids. Prospective studies are needed to confirm these initial observations. This virus should be considered as a possible aetiologic agent in some children with ITP.     

Prevalence of depression in survivors of acute myocardial infarction

OBJECTIVES: To assess the prevalence and persistence of depression in patients with acute myocardial infarction (AMI) and the relationship between assessment modality and prevalence. DATA SOURCES: MEDLINE, Cochrane, CINAHL, PsycINFO, and EMBASE. REVIEW METHODS: A comprehensive search was conducted in March 2004 to identify original research studies published since 1980 that used a standardized interview or validated questionnaire to assess depression. The search was augmented by hand searching of selected journals from October 2003 through April 2004 and references of identified articles and reviews. Studies were excluded if only an abstract was provided, if not in English, or if depression was not measured by a validated method. RESULTS: Major depression was identified in 19.8% (95% confidence interval [CI] 19.1% to 20.6%) of patients using structured interviews (N=10,785, 8 studies). The prevalence of significant depressive symptoms based on a Beck Depression Inventory score > or =10 was 31.1% (CI 29.2% to 33.0%; N=2,273, 6 studies), using a Hospital Anxiety and Depression Scale (HADS) score > or =8%, 15.5% (CI 13.2% to 18.0%; N=863, 4 studies), and with a HADS score > or =11%, 7.3% (CI 5.5% to 9.3%; N=830, 4 studies). Although a significant proportion of patients continued to be depressed in the year after discharge, the limited number of studies and variable follow-up times precluded specification of prevalence rates at given time points. CONCLUSIONS: Depression is common and persistent in AMI survivors. Prevalence varies depending on assessment method, likely reflecting treatment of somatic symptoms.     

Persistence of human multilineage, self-renewing lymphohematopoietic stem cells in chimeric sheep

We have previously reported the ability of uncharacterized human bone marrow (BM) cells to engraft into preimmune fetal sheep, thereby creating sheep-human chimera suitable for in vivo examination of the properties of human hematopoietic stem cells (HSC). Adult human bone marrow CD34+ HLA-DR- cells have been extensively characterized in vitro and have been demonstrated to contain a number of primitive hematopoietic progenitor cells (PHPC). However, the capacity of such highly purified populations of human marrow CD34+ HLA-DR- cells to undergo in vivo self-renewal and multipotential lymphohematopoietic differentiation has not been previously demonstrated. To achieve that, human CD34+ HLA-DR- cells were transplanted in utero into immunoincompetent fetal sheep to investigate the BM-populating potential of these cells. Long-term chimerism, sustained human hematopoiesis, and expression of human cells belonging to all human blood cell lineages were demonstrated in two animals for more than 7 months' posttransplantation. Chimeric BM contained erythroid, granulocytic/monocytic, and megakaryocytic hematopoietic progenitor cells, as well as the primitive high proliferative potential colony- forming cell (HPP-CFC). Under a variety of in vitro experimental conditions, chimeric BM cells gave rise to human T cells expressing T- lymphocyte-specific markers, human natural killer (NK) cells, and human IgG-producing B cells. In vivo expansion and possibly self-renewal of transplanted PHPC was confirmed by the detection in chimeric BM 130 days' posttransplantation of CD34+ HLA-DR- cells, the phenotype of human cells constituting the stem-cell graft. These studies demonstrate not only the BM-populating capacity, multipotential differentiation, and most likely self-renewal capabilities of human CD34+ HLA-DR- cells, but also that this BM population contains human HSC. Furthermore, it appears that this animal model of xenogeneic stem-cell transplantation is extremely useful for in vivo examination of human hematopoiesis and the behavioral and functional characteristics of human HSC.