Biomedical subjects

A Lloyd

Publications and source records attributed to A Lloyd.

At least 73 records · Page 4Linked to original sources

PubMed1998

Predictors of medication compliance after hospital discharge in adolescent psychiatric patients.

Failure in medication compliance in adult psychiatric patients is often found to be due to side effects or associated with unawareness of illness. Little research has been conducted on medication compliance in adolescent psychiatric patients. In this study, 97 adolescent psychiatric patients, including 46 with substance abuse, were followed up an average of 14 months after their discharge from inpatient psychiatric care. Compliance with prescribed medications was examined and the association between several potential predictors and compliance was examined. The overall rate of medication compliance was only 38% at 14-month follow-up, whereas the rate of patients stopping their medications because of side effects was only 23%. Significant predictors of compliance failures were general noncompliance with the discharge plan, followed by postdischarge substance abuse. Side effects did not contribute any additional variance when these factors were considered. These data suggest that medication compliance may be adversely impacted by general tendencies toward noncompliance with treatment, which may be mediated by several possible factors. Interventions to increase awareness of the need for psychotropic medications as well as careful monitoring for substance abuse relapse in this population are suggested.

Adolescent↗

PubMed1998

CCR5 expression correlates with susceptibility of maturing monocytes to human immunodeficiency virus type 1 infection.

The chemokine receptor CCR5 and to a lesser extent CCR3 and CCR2b have been shown to serve as coreceptors for human immunodeficiency virus type 1 (HIV-1) entry into blood- or tissue-derived macrophages. Therefore, we examined the expression of the chemokine receptors CCR1, CCR2b, CCR3, CCR5, and CXCR4 as RNAs or as membrane-expressed antigens in monocytes maturing into macrophages and correlated these results with the susceptibility of macrophages to HIV-1 infection, as measured by their concentrations of extracellular p24 antigen and levels of intracellular HIV DNA by quantitative PCR. There was little change in levels of CCR1, CCR2b, and CCR5 RNAs. CCR3 RNA and surface antigen were undetectable throughout maturation of adherent monocytes over 10 days. CXCR4 RNA and membrane antigen were strongly expressed in newly adherent monocytes, but their levels declined at day 7. The amounts of CCR5 RNA remained stable, but the amounts of CCR5 antigen increased from undetectable to peak levels at day 7 and then declined slightly at day 10. Levels of susceptibility to laboratory (HIV-1BaL) and clinical strains of HIV-1 showed parallel kinetics, peaking at day 7 and then decreasing at days 10 to 14. The concordance of levels of HIV DNA and p24 antigen suggested that the changes in susceptibility with monocyte maturation were at or immediately after entry and correlated well with CCR5 expression and inversely with CXCR4 expression.

Base Sequence↗

PubMed1998

Chronic fatigue syndrome: an immunological perspective.

OBJECTIVE: The aim of this study is to review research examining an immunological basis for chronic fatigue syndrome (CFS) and to discuss how a disturbance in immunity could produce central nervous system (CNS)-mediated symptoms. METHOD: Data relevant to the hypothesis that abnormal cytokine release plays a role in the pathogenesis of CFS are reviewed as well as recent evidence relating to potential mechanisms by which immune products may enter the brain and produce a disturbance in CNS processes. RESULTS: Examinations of cytokine levels in patients with CFS have produced inconclusive results. Recent evidence suggests that abnormal release of cytokines within the CNS may cause neural dysfunction by a variety of complex mechanisms. CONCLUSION: Neuropsychiatric symptoms in patients with CFS may be more closely related to disordered cytokine production by glial cells within the CNS than to circulating cytokines. This possibility is discussed in the context of unresolved issues in the pathogenesis of CFS.

Central Nervous System↗

PubMed1997

Different kinetics of senescence in human fibroblasts and peritoneal mesothelial cells.

Senescence has been reported for a wide variety of human cell types. In cultures of human fibroblasts the process is due to a percentage of the cells becoming senescent at each passage rather than all the cells entering senescence simultaneously at the end of the life span. By measuring the percentage of fibroblasts which are still cycling at each passage, a rate of decline in the growth fraction, which mirrors the rate of senescence, can be obtained. However, such an analysis has never been undertaken in multiple cell types using the same method to identify cycling cells. It is thus unknown if the rate of senescence is the same or different in cultures of different human cell types. To answer this question the rates of decline in the cycling fractions were simultaneously measured in two cultures of human cells (AGO7086A, peritoneal mesothelial cells; and 2DD, human dermal fibroblasts) which have practically identical in vitro life spans. 2DD fibroblasts showed a rate of decline of 0.89% cycling cells per population doubling when the data obtained were fitted to a simple linear equation. However, AGO7086A gave a decline of approximately 2.2% per population doubling. Thus mesothelial cells enter senescence significantly faster than fibroblasts (P < 0.001). This decline in the growth fraction was accompanied by an increasing fraction of mesothelial cells which retained detectable endogenous beta-galactosidase activity at pH 6. Such activity has previously been shown to be associated with senescent human fibroblasts. These findings suggest that the process of senescence has common features in different cell lineages but that the rate of the process can differ markedly between them.

Biomarkers↗

PubMed1997

Expression of TNF-alpha by human plasma cells in chronic inflammation.

Tumor necrosis factor-alpha (TNF-alpha) is a potent pro-inflammatory cytokine and mediator of the inflammatory response. It has been implicated in the pathogenesis of many inflammatory disorders, including rheumatoid arthritis (RA), septic shock, and Crohn's disease. Using a specific anti-human TNF-alpha antibody we detected immunoreactivity for this cytokine in the cytoplasm of inflammatory cells in several chronic inflammatory disorders, including RA, scleritis, and polyarteritis nodosa. These cells were identified predominantly as IgG-expressing plasma cells. Lymph nodes from patients with Hodgkin's lymphoma and breast cancer, but not from control subjects, were also found to contain TNF-alpha-positive plasma cells. Cultured EBV-B lymphocytes and a human plasma cell line (ARH-77) when stimulated with phorbol myristate acetate demonstrated cytoplasmic TNF-alpha immunoreactivity. Western blot analysis of cell membranes and conditioned media from both cell types revealed the presence of the 26-kDa membrane-bound from and the 17-kDa soluble from of TNF-alpha, respectively. TNF-alpha was quantitated by enzyme-linked immunosorbent assay and found to be biologically active as determined by the L929 cytotoxicity assay. This is the first demonstration that plasma cells may be capable of modulating immune and inflammatory responses, not only by antibody production, but also by their secretion of a key inflammatory mediator, TNF-alpha.

Animals↗

PubMed1997

Intravenous immunoglobulin is ineffective in the treatment of patients with chronic fatigue syndrome.

PURPOSE: To determine whether the reported therapeutic benefit of intravenous immunoglobulin in patients with chronic fatigue syndrome (CFS) is dose dependent. PATIENTS AND METHODS: Ninety-nine adult patients, who fulfilled diagnostic criteria for CFS, participated in this double-blind, randomized, and placebo-controlled trial. Patients received intravenous infusions with either a placebo solution (1% albumin) or one of three doses of immunoglobulin (0.5, 1, or 2 g/kg) on a monthly basis for 3 months, followed by a treatment-free follow-up period of 3 months. Outcome was assessed by changes in a series of self-reported measures (quality-of-life visual analog scales, standardized diaries of daily activities, the profile of mood states questionnaire) and the Karnofsky performance scale. Cell-mediated immunity was evaluated by T-cell subset analysis and delayed-type hypersensitivity (DTH) skin testing. RESULTS: No dose of intravenous immunoglobulin was associated with a specific therapeutic benefit. Adverse reactions, typically constitutional symptoms, were reported by 70% to 80% of patients, with no relationship to immunoglobulin treatment. CONCLUSIONS: Intravenous immunoglobulin cannot be recommended as a therapy for the treatment of CFS. A better understanding of the pathophysiology of this disorder is needed before effective treatment can be developed.

Activities of Daily Living↗

PubMed1997

Microleakage of Diaket and amalgam in root-end cavities prepared using MicroMega sonic retro-prep tips.

The in vitro sealing ability of the root-canal sealer Diaket when used as a root-end filling material was compared with that of amalgam using linear micro-leakage of Indian ink. Eight groups of 20 extracted teeth each were formed, plus 12 control teeth as follows: 1) root-end resection of 45 degrees bevel, root-end cavity preparation with an 008 round bur, amalgam root-end filling; 2) 45 degrees bevel, bur, Diaket; 3) 45 degrees bevel, using a sonic retro-prep tip, amalgam; 4) 45 degrees bevel, sonic, Diaket; 5) no bevel, bur, amalgam; 6) no bevel, bur, Diaket; 7) no bevel, sonic, amalgam; 8) no bevel, sonic, Diaket. Root-end cavity depths of 3 mm were prepared. Specimens were immersed in Indian ink for 2 weeks. The teeth were demineralized, rendered transparent and linear dye penetration recorded. Results showed that Diaket provided a superior seal to amalgam irrespective of the root-end preparation. The degree of bevel of the resected root-end did not influence leakage. Sonic instrumentation resulted in a larger root-end cavity than with burs.

Apicoectomy↗

PubMed1997

Chemokines in acute anterior uveitis.

PURPOSE: The aim of this study was to define the expression of chemoattractant cytokines (chemokines) in human aqueous humor, obtained from patients with idiopathic acute anterior uveitis (AU). The chemokines assayed included macrophage inflammatory proteins-1 alpha and -1 beta (MIP-1 alpha and -1 beta), monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), interferon-inducible protein-10 (IP-10), and regulated on activation, normal T-expressed and secreted (RANTES). METHODS: We studied fifteen patients (7 females) with idiopathic acute AU, at various stages of disease activity, and two control subjects undergoing elective cataract extraction. Aqueous humor was collected under aseptic conditions, after obtaining informed consent. Chemokine concentrations were measured using specific ELISA. Correlation was sought between chemokine concentrations and disease activity, evaluated by slit lamp biomicroscopy and graded using a standardized scale of disease severity. RESULTS: IL-8 was detected (35.9 +/- 13.6, mean +/- SE) in three of seven subjects in active, untreated stages of AU (clinical score 2-4), and it was undetectable in subjects sampled in the quiescent phase of the disease. IP-10 had a mean concentration of 40.6 ng/ml +/- 20.9 in the active group (N = 7), declining to 0.8 ng/ml +/- 0.3 in the samples from patients with inactive disease (N = 7, P = 0.001). Similarly, substantial expression of MCP-1 was noted, with a maximum concentration of 145 ng/ml, in acute (active) AU (N = 6), (26.7 +/- 19.7), falling to undetectable levels in those with inactive disease, and in control subjects (P = 0.001). MIP-1 beta (N = 7), (3.4 +/- 1.5, P = 0.001) and RANTES (N = 7, 8.8 +/- 4.2) levels were significantly increased in acute disease (P = 0.001) and related to the activity of the disease, although the concentrations were not as high as MCP-1, IP-10 and IL-8. IP-10, RANTES and MIP-1 beta were detected at low concentrations in the aqueous humor of the control subjects. CONCLUSIONS: This is the first study of chemokine concentrations in the aqueous humor of patients with acute anterior uveitis. The concentration of chemokines: IL-8, IP-10, MCP-1, RANTES and MIP-1 beta were significantly increased during the active stages of AU, and correlated with the clinical severity of the disease. These chemoattractant cytokines probably play a critical role in leucocyte recruitment in acute AU.

Acute Disease↗

PubMed1997

Shaping ability of the M4 handpiece and Safety Hedstrom files in simulated root canals.

The aim of this study was to assess the shaping ability of the M4 reciprocating handpiece and Safety Hedstrom files in simulated canals. A total of 40 simulated canals of various angles and positions of curvature were prepared with an M4 handpiece using Safety Hedstrom files oriented with the ground, flattened surface towards the inner aspect of the curve. A standard regimen was adopted throughout. Pre- and post-operative longitudinal images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount and location of resin material removed as a result of preparation were determined from composite images of superimposed pre- and post-operative views. Preparation time varied significantly (P < 0.001) between the canal types; overall, 20 degrees canals were prepared more quickly than 40 degrees canals. Zips and elbows were observed in 16 out of the 40 canals with most (11) being created in 40 degrees specimens. Ledges were found in 19 canals and perforations in only 1. There were no significant differences between canal shapes for these aberrations. Excessive removal of material from the inner aspect of the canal at the curve to create a danger zone was found in 20 canals, but only in those with 40 degrees curves. Significant differences in total canal width between the canal types were seen at the zips (P < 0.05), elbows (P < 0.05) and danger zones (P < 0.001). Transportation at the danger zones varied significantly (P < 0.001) between canal types. Under the conditions of this study, the M4 handpiece and Safety Hedstrom files created hour-glass preparations in a substantial proportion of canals. In reality, the Safety Hedstrom file with its one flattened surface was ineffective at reducing removal of material along the inner aspect of canal curves in severely curved specimens and clearly has the potential to create strip perforations in teeth.

Analysis of Variance↗

PubMed1997

Cognitive deficits in patients suffering from chronic fatigue syndrome, acute infective illness or depression.

BACKGROUND: Patients with chronic fatigue syndrome (CFS) report neuro-psychological symptoms as a characteristic feature. We sought to assess cognitive performance in patients with CFS, and compare cognitive performance and subjective workload experience of these patients with that of two disease comparison groups (non-melancholic depression and acute infection) and healthy controls. METHOD: A computerized performance battery employed to assess cognitive functioning included tests of continuous attention, response speed, performance accuracy and memory. Severity of mood disturbance and subjective fatigue were assessed by questionnaire. RESULTS: All patient groups demonstrated increased errors and slower reaction times, and gave higher workload ratings than healthy controls. Patients with CFS and non-melancholic depression had more severe deficits than patients with acute infection. All patient groups reported more severe mood disturbance and fatigue than healthy controls, but patients with CFS and those with acute infection reported less severe mood disturbance than patients with depression. CONCLUSIONS: As all patients demonstrated similar deficits in attention and response speed, it is possible that common pathophysiological processes are involved. The differences in severity of mood disturbance, however, suggest that the pathophysiological processes in patients with CFS and acute infection are not simply secondary to depressed mood.

Acute Disease↗

PubMed1997

Economic evaluation of the use of nadroparin calcium in the prophylaxis of deep vein thrombosis and pulmonary embolism in surgical patients in Italy.

The objective of this study was to compare the costs, from the perspective of the payer, of using nadroparin calcium, a low-molecular-weight heparin, instead of unfractionated heparin in the prophylaxis of venous thromboembolism in patients undergoing orthopaedic surgery or major general surgery in Italy. The methods used were based on a published meta-analysis and a survey of clinical practice. We constructed a model of the prophylaxis and management of venous thromboembolism in Italy. Resource use associated with individual events was estimated on the basis of the clinical survey. Unit costs, not available from published sources, were taken from charges made by hospitals and from direct observation. A sensitivity analysis was conducted to examine whether the results were robust to changes in key variables. In the base case, compared with unfractionated heparin, prophylaxis with nadroparin calcium reduced the expected costs of managing thromboembolism by 267,226 Italian lire (L, 1994 values; $US1 = L1600 approx.) per patient undergoing orthopaedic surgery, and by L45,588 per patient undergoing major general surgery. Therefore, switching from unfractionated heparin to nadroparin calcium in these patients offers the possibility of significant cost savings to the Italian healthcare system.

Fibrinolytic Agents↗

PubMed1997

Molecular biology and the major psychoses.

OBJECTIVE: To highlight the potential role of molecular biological studies in examining the expression of genes of interest in brain tissue to elucidate the pathophysiological basis of the major psychoses. METHOD: To review the principles underlying the available techniques for expression studies. RESULTS: Detection of messenger RNA by in situ hybridisation and quantitation by Northern analysis are powerful tools to detect abnormalities in gene expression in brain tissue. CONCLUSION: The availability of simple techniques to examine the expression of RNA and protein products of individual genes, including examination at the level of individual cells, offers a clear opportunity to define the molecular basis of the major psychoses.

Brain↗

PubMed1997

Molecular biological investigations into the role of the NMDA receptor in the pathophysiology of schizophrenia.

OBJECTIVE: There is increasing acceptance that schizophrenia is associated with a generalised disorder in cortical neurodevelopment. The aim of this paper is to review the evidence that this disorder may be accounted for by abnormalities in mechanisms mediated by the main family of excitatory neuroreceptors in cortical brain systems, the N-methyl-D-aspartate (NMDA) glutamatergic receptors. METHOD: The neurobiological evidence is presented for an abnormality in cortical development related to synaptic pathology in schizophrenia. The unique functions of the NMDA receptor in information processing are described, especially its role in learning and memory, and in neural plasticity and brain development. It is argued that the cellular and molecular mechanisms which underlie learning and memory also govern normal brain development. Studies examining abnormalities in glutamatergic transmission in schizophrenia are reviewed. RESULTS: There is a substantial literature in support of the possibility that NMDA receptor abnormalities may be involved in the neurodevelopmental predisposition to schizophrenia, as well as in symptom production. CONCLUSIONS: Research to determine the role of the NMDA receptor in the pathophysiology of schizophrenia is warranted and now feasible. To be successful, this research will require the application of molecular biology techniques to postmortem brain tissue studies, in addition to traditional histochemical approaches.

Cerebral Cortex↗

PubMed1997

Utilising molecular biological and histopathological techniques to study the dopaminergic system in patients with melancholia.

OBJECTIVE: To describe the rationale for investigating the dopaminergic system in patients with melancholia by applying molecular biological (notably, in situ hybridisation) and histopathological techniques in postmortem brain tissue. METHOD: Relevant advances in the functional neuroanatomy of frontostriatal circuits, as well as insights from clinical neuroimaging studies in primary and secondary depressive disorders, are presented. These are integrated with developments in the pharmacological and molecular characteristics of dopamine receptor subtypes and recognition of their selective anatomical distribution. RESULTS: Converging data from the basic and clinical neurosciences suggest that the pathophysiology of depressive disorders characterised by psychomotor phenomena, such as melancholia, may involve dysregulation of dopaminergic mechanisms within complex frontostriatal circuits. CONCLUSIONS: The key feature of in situ hybridisation is its capacity to test for variations in the functional components of designated biochemical systems within highly specific anatomical regions. We utilise this approach, in combination with relevant histopathological techniques, to test the structural and functional integrity of the dopaminergic system within key fronto-striatal circuits in patients who had exhibited psychomotor phenomena. The same approach can also be used to study the integrity of other relevant biochemical systems, such as the serotoninergic and noradrenergic systems, in patients with other mood disorders.

Brain Mapping↗

PubMed1997

Increased expression of matrix metalloproteinases in vivo in scleritis tissue and in vitro in cultured human scleral fibroblasts.

Scleritis is a sight-threatening inflammatory disorder of the eye characterized by the degradation of scleral matrix. Matrix metalloproteinases (MMPs) are ubiquitous proteolytic enzymes important in physiological and pathological processes, the activity of which is stringently controlled by the action of a family of natural antagonists, the tissue inhibitors of matrix metalloproteinases (TIMPs). We hypothesized that enhanced expression of MMPs, without the negative regulatory influence of TIMPs, may be a key feature of tissue destruction in inflammatory eye diseases, such as scleritis. The aim of this study was to localize and characterize cells expressing MMPs and TIMPs in sclera affected by necrotizing scleritis and, in a parallel study, to establish whether cytokines modulate MMP expression in cultured human scleral fibroblasts. In situ hybridization and immunohistochemical analyses indicated that resident scleral fibroblasts as well as inflammatory cells such as macrophages and T lymphocytes express stromelysin, gelatinase B, and TIMP-1 in necrotizing scleritis tissue. In addition, cytoplasmic immunoreactivity for tumor necrosis factor-alpha, an inducer of MMPs, was detected in infiltrating inflammatory cells. Cultured scleral fibroblasts stimulated with the combination of interleukin-1 alpha plus tumor necrosis factor-alpha increased TIMP-1 mRNA twofold above constitutive levels. By contrast, these cytokines induced a sevenfold increase in the steady-state levels of stromelysin mRNA. Using Western blotting, stromelysin and TIMP-1 protein production paralleled mRNA induction in cytokine-stimulated human scleral fibroblasts. Culture supernatants harvested from cytokine-stimulated human scleral fibroblasts were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis gelatin substrate zymography. Our results revealed a prominent 92-kd gelatinolytic band corresponding to gelatinase B, which was inducible with interleukin-1 alpha. These data provide evidence for our hypothesis, that an imbalance between enzyme/inhibitor ratios may be the underlying mechanism of the tissue destruction characteristic of scleritis. Our results demonstrate the potential involvement of MMPs and their modulation by cytokines produced by infiltrating inflammatory cells in destructive ocular inflammation.

Adult↗

PubMed1996

Increased production of interleukin-2 (IL-2) but not soluble interleukin-2 receptors (sIL-2R) in unmedicated patients with schizophrenia and schizophreniform disorder.

This study investigated immune activation, as measured by production of interleukin-2 (IL-2) and soluble interleukin-2 receptors (sIL-2R) from stimulated lymphocytes, in schizophrenia and schizophreniform disorder. The study included 13 neuroleptic-free patients, 13 medicated patients and 13 age- and sex-matched control subjects. Production of IL-2 and sIL-2R by peripheral blood mononuclear cells (PBMCs) was measured after in vitro stimulation with phytohaemagglutinin (PHA). Patients' symptoms were rated on the Scales for Assessment of Positive (SAPS) and Negative Symptoms (SANS) and the Brief Psychiatric Rating Scale (BPRS). IL-2 production by stimulated lymphocytes was significantly elevated in neuroleptic-free patients compared with both medicated patients and control subjects. IL-2 production was inversely correlated with the SAPS subscales of bizarre behaviour and formal thought disorder. The pattern of increased IL-2 production is in contrast to previous findings in patients with schizophrenia. Significant associations with clinical rating scores suggest that IL-2 production may vary in different biological subgroups of schizophrenia and schizophreniform disorder.

Adult↗

PubMed1996

Fluconazole versus oral polyenes in the prophylaxis of immunocompromised patients: a cost-minimization analysis.

This study compares 100 mg daily fluconazole with oral polyenes four times daily in the prophylaxis of fungal infections in immunocompromised patients, to determine a cost-minimization strategy. Data was gathered through a literature survey and clinical interviews conducted in nine different UK hospitals. This was used to construct a decision tree, modelling the drug choices available to a clinician at various stages of a patient's treatment, and assigning probabilities to the different corresponding outcomes. UK cost data were fed into this model to determine the expected cost per patient of the different prophylaxis strategies. Two different patient groups were considered: chemotherapy-only patients, and bone-marrow-transplant (BMT) patients who have higher risks of fungal infection. Probabilities derived from the literature suggest that a cost-minimization strategy to manage both chemotherapy patients and BMT patients is to administer oral fluconazole, both as prophylaxis and as first line treatment, against superficial fungal infection. Probabilities gathered from clinical interviews yield similar results, suggesting that the cost-minimization strategy with chemotherapy-only patients is to administer oral polyenes as prophylaxis, and oral fluconazole in case of superficial fungal infection, while for BMT patients it is a combination of fluconazole and oral polyenes as prophylaxis, with oral fluconazole for the treatment of superficial fungal infections. Using the probabilities from the literature, the lowest cost strategies produce an expected cost of pounds 567.20 for chemotherapy-only patients, and an expected cost of pounds 804.87 for BMT patients for a course of treatment lasting from seven to 28 days. The clinical interview probabilities produce expected costs of pounds 826.48 and pounds 1529.43, respectively. Sensitivity analysis was then conducted, and it was found that in the majority of cases, using the literature probabilities, the cost-minimizing strategy remained prophylaxis with oral fluconazole. The sensitivity analysis for chemotherapy-only patients using the interview probabilities tended to favour oral polyenes as the cost-minimization strategy, whereas for BMT patients the sensitivity analysis favoured a combination of fluconazole and oral polyenes in the majority of cases. The key economic advantage of prophylaxis with fluconazole or a combination of fluconazole with oral polyenes in the prophylaxis of fungal infection in immunocompromised patients, results from the reduction of the expected cost of subsequent fungal infection among those who are most at risk.

Antifungal Agents↗

PubMed1996

Root-end cavity preparation using the MicroMega Sonic Retro-prep Tip. SEM analysis.

The objective of this laboratory study was to compare root-end cavities prepared with sonic Retro-prep tips in a MM1500 Sonic Air handpiece with those created by burs in a conventional handpiece. A total of 80 single-rooted extracted human teeth with mature apices and straight canals were included in the study. Four groups of 20 extracted teeth were prepared as follows: I, a 3-4 mm root-end resection perpendicular to the long axis of the root, with a size 40 sonic Retro-prep tip creating an apical cavity 3 mm into root canal system; II, a 45 degrees bevel of the root-face removing a 3-4 mm root segment and root-end preparation as per group I; III, root-end resection as per group I, with an apical cavity prepared using a size 010 inverted cone bur 3 mm down the long axis of the root; IV, resection as per group II, followed by an apical cavity preparation with a size 010 inverted cone bur 3 mm into the root canal system. The apical root portion and root-end cavities were replicated and prepared for SEM analysis at x 20 and x 80 magnification. The degree of chipping associated with the margin of the root-end cavities, as evaluated with a standard grading system, and the incidence of root-face cracks were noted. Marginal chipping of root-end cavities prepared using sonic instrumentation was significantly worse than that produced by burs (P < 0.001). Perpendicular root-end resections showed significantly better scores than bevelled root-end resections (P < 0.005). The incidence of root-face cracking was low with no significant difference between the experimental groups.

Dental Instruments↗