Considerations in the management of transposed teeth

AIM: To review the management of transposed teeth, and to illustrate the treatment options with four case reports. METHODS: The aetiology and management of transposed teeth are reviewed. Three management options are discussed: correcting the order of transposed teeth, maintaining the order of transposed teeth, and extraction of one of the transposed teeth. Methods of camouflaging transposed teeth are described in detail. The treatment options are illustrated with case reports.     

Morphologic, functional and behavioral effects of titanium dioxide exposure on nerves

OBJECTIVES: The purpose of this study was to explore morphologic, functional, and behavioral effects of titanium dioxide (TiO(2)) on nerves. MATERIAL AND METHODS: A total of 17 albino rats were used for nerve conduction experiments, hot-plate tests, and histological evaluation. TiO(2) was implanted unilaterally on the sciatic nerves of five rats. Ten days after surgery, test and control nerves were dissected and their signal transduction speeds were quantified by suction electrodes in a bath containing a Tyrode solution. Twelve rats were divided into three equal groups resulting in equal number of nerves (n=8) for TiO(2) implantation, surgical exposure of the nerves, and for use as controls. One week after surgery, hot-plate tests were undertaken for 10 consecutive days to determine response latencies of the nerves. At the termination of the experiments, the nerves were harvested, processed, and examined under a microscope. RESULTS: The signal transduction speeds of TiO(2)-implanted nerves was similar to control specimens (P>0.05). The avoidance responses of TiO(2)-implanted, surgically exposed, and control nerves were comparable (P>0.05). At the cellular level, TiO(2) did not lead to any signs of adverse reactions on nerves. CONCLUSIONS: TiO(2), the main oxide surrounding endosseous titanium implants, does not alter the structure and the function of myelinated nerves.     

Condylar asymmetry measurements in patients with temporomandibular disorders

OBJECTIVES: The relationship between condylar asymmetry and handedness of the patients with temporomandibular disorders (TMD) and patients with no signs or symptoms of TMD was investigated. The experimental group consisted of 25 patients aged 15 to 52 years who were referred for treatment of TMD. The mean age of this group was 26.24 years. The control group consisted of 25 patients aged 14 to 52 years (mean age: 26.16 years). METHODS: The formula by Habets et al.14 was used to express the symmetry between the condyles and the rami on the orthopantomogram (OPG) image. Differences between both groups and subgroups (condyle, ramus, condyle plus ramus) regarding symmetry were calculated with the Student's t-test. RESULTS: The mean of condylar asymmetry was found to be 11.11 +/- 11.03% in the TMD group. However, in the control group, the mean of condylar asymmetry was found to be 8.36 +/- 6.27%. No statistically significant differences were found between condylar asymmetry in both groups (p>0.05). CONCLUSIONS: No statistically significant differences were found between condylar asymmetry index in patients with TMD according to myogenous problems and in patients with no signs or symptoms of TMD.     

Extubation failure in the elderly

To determine the causes, risk factors and complications of planned extubation failure of critically ill elderly patients, we conducted a prospective study of 175 consecutive patients (> or = 70 years old) admitted with respiratory failure. Thirty-six (21%) failed extubation within 72 h after planned extubation. Compared to a younger age group (< 70 years old) matched for severity of illness, inability to handle secretions (20%) was the most common reason of airway causes leading to extubation failure in the elderly while upper airway obstruction (22%) was the predominant cause in the control group. As for nonairway causes, COPD related hypercapnic respiratory failure accounted for the majority of cases in both groups. After adjusting for severity of illness, elderly patients who required reintubation had a higher risk of developing nosocomial pneumonia. The presence of underlying pulmonary disease (odds ratio (OR), 2.9; 95% confidence interval (CI) 1.2-6.9), length of intubation > 4 days (OR, 4.3; 95% CI 1.8-10.2), and albumin levels < 2.5 g/dl (OR, 2.7; 95% CI 1.2-6.7) were independently associated with extubation failure in the old. Objective measurements of cough strength and secretion volume are needed to reduce the morbidity of elderly patients at risk for extubation failure.     

Implantable cardioverter-defibrillator malfunction due to mechanical failure of the header connection

Four cases of ICD system malfunction occurring within the Medtronic Marquis family over a limited time frame are reported. These cases shared a common element of defective connections between the header post and the right ventricular pace/sense terminal pin that required intervention and reconnection. Inappropriate shocks occurred in two cases. The circumstances of these cases provide important information about the potential difficulties with these devices and highlight the deficiencies of the current system in tracking and analyzing device-related problems.     

Hippocampal dysfunction in Gulf War Syndrome. A proton MR spectroscopy study

The pathogenesis of Gulf War Syndrome (GWS) is not clearly understood. Data exist to suggest that GWS may originate from a combination of chronic fatigue and sensitivity to the exposure of exogenous agents. Since the head region of hippocampus is highly vascularized and thus vulnerable to toxic substances in circulation, we postulated that hippocampal impairment occurs in GWS. To test this, single volume localized in vivo proton MR spectroscopy (MRS) studies of the left and right hippocampi of consenting Gulf War veterans (N=15; 10 with GWS, and 5 without GWS) and control Vietnam veterans (N=6) were conducted in accordance with approved human study protocols. The N-acetyl aspartate (NAA) to creatine and choline to creatine ratios were computed from the spectra. The NAA/creatine ratio of the GWS group (N=10) was found to be significantly lower than that of the entire control group (N=11) or the unaffected GW control group (N=5). No laterality differences were observed among any of the three groups. The choline/creatine ratio of the GWS group was not different from that for either control group. To check the existence of any relationship between age and the NAA/creatine ratios, the entire study population was grouped into those below or above the median age (44.3 years). It was found that the NAA/Cre ratio of the younger group (only Gulf War veterans) was significantly lower than that of the older group. The lower NAA/creatine ratio for the GWS group points to the existence of hippocampal dysfunction.     

Immunofluorescent labeling of increased calpain expression and neuronal death in the spinal cord of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice

Parkinson's disease (PD) is a movement disorder characterized by rigidity, tremor, and bradykinesia, originating from degeneration of dopaminergic neurons in the substantia nigra (SN), retrorubral area, and locus ceoruleus (LC). Calpain has been implicated in the pathophysiology of neurodegenerative diseases. Since the spinal cord (SC) and brain are integrally connected and calpain is involved in cell death and mitochondrial dysfunction, we hypothesized that SC neurons are also affected in PD. In order to examine this hypothesis, we examined both brain and SC from mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). To identify cells expressing calpain, double immunofluorescent labeling was performed with antibodies specific for calpain and a cell type (OX-42, GFAP, or NeuN). Combined terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and double immunofluorescent labeling were used to identify death of specific cells in the central nervous system (CNS). There was an increase in calpain expression in microglia, astrocytes, and neurons in the SC of MPTP-treated mice at 1 and 7 days, as compared to controls. TUNEL-positive neurons in the SC and SN showed apoptotic characteristics. These results demonstrated that neuronal death occurred not only in SN but also in the SC of MPTP-treated mice and has provided evidence for a possible calpain-mediated SC neuronal death in MPTP-induced parkinsonism in mice.     

N-terminal heterogenicity of amyloid protein examined in Alzheimer's disease

Alzheimer's disease is the major cause of dementia in humans. The affected brain shows characteristic abnormal filamentous proteins that accumulate intracellularly as neurofibrillary tangles, and extracellularly as senile plaques, as well as in cerebral blood vessels. The extracellular deposits are an amyloid protein, which is highly insoluble. In our study, we intended to show that the N-terminus of amyloid A4 protein can change in length and sequence in Alzheimer's disease, and possibly in other dementias.