Implant retention systems for implant-retained overdentures

Implant retained overdentures are being increasingly utilised in both general and specialist practice to rehabilitate patients with missing teeth, particularly those that are edentate. This article aims to inform the reader of a variety of retention systems that are available to retain an implant overdenture and to understand how these systems work, their advantages and disadvantages and to outline some of the clinical and treatment planning considerations involved in selecting the most appropriate retention system for patients.

Removal techniques for failed implants

The use of dental implants is an accepted and predictable way of replacing missing or lost teeth. However, implants can and will fail and there are a variety of reasons why this occurs, which the practitioner should understand. In some instances failed implants may require removal and, therefore, practitioners should be aware of techniques that can be used to remove failed implants to potentially enable future rehabilitation of an edentulous region.

A study of the clinical characteristics of benign trigeminal sensory neuropathy

PURPOSE

The purpose of this study was to describe the clinical characteristics of a series of patients presenting with benign trigeminal sensory neuropathy.

PATIENTS AND METHODS

We conducted a retrospective analysis of the clinical and pathologic characteristics of 23 patients presenting with facial numbness of unknown etiology.

RESULTS

Patients presented with diverse medical histories but could be grouped into those with a connective tissue disorder, neurologic disease, psychologic problems, or a medical history of unknown significance. The age of the patient, the severity and distribution of the trigeminal neuropathy, and symptoms other than neuropathy closely reflected the patient's medical history. The majority of patients underwent magnetic resonance imaging, but the results did not facilitate the diagnosis of the condition or reflect the extent and severity of the symptoms. In 60% of patients, the symptoms remained unchanged during the course of the study and outcome was not influenced by medical treatment.

CONCLUSIONS

The diagnosis and management of benign trigeminal sensory neuropathy remain a significant clinical challenge.

Clinical factors associated with the development of phlebitis after insertion of a peripherally inserted central catheter

A descriptive comparison study was conducted to determine if there were any coagulation, immune, nutritional, or insertion-related differences between 64 adult hospitalized clients who experienced phlebitis after insertion of a peripherally inserted central catheter (PICC) compared with a matched group of 64 adult hospitalized clients who did not develop phlebitis. Factors that significantly decreased the development of phlebitis in this study included smaller catheter gauge, placement in the basilic vein, tip location in the superior vena cava, no manipulation or movement at the exit site, and higher platelet levels.

High level engraftment of NOD/SCID mice by primitive normal and leukemic hematopoietic cells from patients with chronic myeloid leukemia in chronic phase

We have previously shown that intravenously injected peripheral blood (PB) or bone marrow (BM) cells from newly diagnosed chronic myeloid leukemia (CML) patients can engraft the BM of sublethally irradiated severe combined immunodeficient (SCID) mice. We now report engraftment results for chronic phase CML cells in nonobese diabetic (NOD)/SCID recipients which show the superiority of this latter model. Transplantation of NOD/SCID mice with 7 to 10 x 10(7) patient PB or BM cells resulted in the continuing presence of human cells in the BM of the mice for up to 7 months, and primitive human CD34+ cells, including those detectable as colony-forming cells (CFC), as long-term culture-initiating cells, or by their coexpression of Thy-1, were found in a higher proportion of the NOD/SCID recipients analyzed, and at higher levels than were seen previously in SCID recipients. The human CFC and total human cells present in the BM of the NOD/SCID mice transplanted with CML cells also contained higher proportions of leukemic cells than were obtained in the SCID model, and NOD/SCID mice could be repopulated with transplants of enriched CD34+ cells from patients with CML. These results suggest that the NOD/SCID mouse may allow greater engraftment and amplification of both normal and leukemic (Ph+) cells sufficient for the quantitation and characterization of the normal and leukemic stem cells present in patients with CML. In addition, this model should make practical the investigation of mechanisms underlying progression of the disease and the development of more effective in vivo therapies.

Minimal residual disease in bone marrow transplant recipients with chronic myeloid leukemia

Bone marrow samples of 70 transplant recipients with CML were studied by Southern blot analysis and RT-PCR using a two-step procedure with nested primers. Twenty-two patients were studied once and 48 were assessed on multiple occasions. All patients remained in a hematological remission during the study. The time of follow-up after the transplant ranged from 2 to 144 months with a median of 42 months. Thirty-nine patients (56%) were negative by RT-PCR and Southern blot studies at the time of their last evaluation. The proportion of RT-PCR negative patients increased with the duration of follow-up after the transplant; 36% of patients were RT-PCR negative after 1 year compared with 60% after 2 years and 78% after > or = 5 years. Patients maintained on immunosuppression had a higher probability of remaining RT-PCR positive. Age, sex, time from diagnosis to BMT, as well as acute and chronic GVHD did not influence the RT-PCR status. The majority of patients studied on multiple occasions demonstrated a stable RT-PCR and Southern blot pattern. Some showed uni- or multi-directional transitions. However, none of the patients studied progressed to a hematological relapse. RT-PCR studies on colonies grown from RT-PCR positive. Southern blot negative patients confirmed that some of the clonogenic progenitors are able to produce BCR/ABL transcripts.

A human lymphoma cell line with multiple immunoglobulin rearrangements

The development of a cell culture system efficient in the establishment of lymphoma cell lines has made it possible to dissect basic biological and molecular aspects of lymphoma cells. We have established a lymphoma cell line from a patient with B cell lymphoma. The cell line has a complex karyotype with translocations involving bands 8q24, 14q32, and 18q21. Molecular analysis revealed that the Myc gene was rearranged; we were unable to demonstrate rearrangement of the Bcl-2 gene. Evaluation of the structure of the heavy chain Ig genes revealed that the cell line carried the same rearrangements as the cells from which the cell line was derived. The pattern of rearrangement, however, was unusual in that there were at least four rearranged bands when DNA cut with HindIII was probed with a fragment of the heavy chain joining region. To further characterize the cell line, subclones were derived. Individual subclones had the same pattern of rearrangement as the parent cell line. The results of these studies provide evidence that multiple rearranged Ig genes may be present in a single clone of cells.

Spontaneous phenotypic and karyotypic progression in the SV40 transfected cell line SVG during prolonged passage in vitro

Transfection of primary cultures of human cells with origin of replication deficient SV40 DNA has been carried out by others to generate in vitro models of malignant transformation in vivo. The present work describes progressive alterations in karyotype and phenotype in one such transfected (neuroglial) cell line (SVG). After repeated passage, recognisable marker chromosomes evolved. These may be related to karyotypic anomalies found in human glial tumors. Accompanying the evolution in karyotype were changes in phenotype. Although presaging malignant transformation, these stopped short of actual tumorigenicity.

Molecular pathology of chronic myelogenous leukemia

The presence of Philadelphia chromosome t(9:22) is a hallmark of 95% of clinical cases of chronic myelogenous leukemia (CML) as well as 20% of adult acute lymphoblastic leukemia (ALL) and 5% of acute myeloid leukemia (AML). The product of t(9;22) is a fusion protein BCR-ABL. The fusion proteins of CML, ALL and AML have increased tyrosine kinase activity and show a transforming potential in vitro and in animal models. The shorter p190 protein is associated almost only with ALL and AML, while the protein p210 is present in both chronic phase and blast crisis of CML and also in 50% of Philadelphia-positive (Ph1+) ALL. In CML the transition from chronic phase to blast crisis is usually accompanied by additional genetic events, e.g. additional chromosomal abnormalities, and oncogene activation(s). The detailed understanding of molecular basis of CML, and Ph1+ ALL and AML provides highly sensitive molecular and serological methods to complement classical cytogenetics. The advantages and limitations of these techniques are described and discussed below.