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PubMed2004

[Morning stiffness].

STIFFNESS AND UNSTRETCHING: Morning stiffness in the elderly is a painful entity often ignored, but frequent in institutions. Unstretching in the morning is part of the criteria in the diagnosis of inflammatory pathologies, but morning stiffness in old patients appears different from that described in rheumatological diseases and arthrosis. FROM AN AETIOLOGICAL POINT OF VIEW: Various affections can be accompanied by morning stiffness in an elderly patient: arthrosis, but also various consequential affections, static disorders, deformity. We felt it was important to define the precise criteria that individualise this pathology so as to improve its management. MANAGEMENT: Non-medicinal measures often reduce the intensity and duration of this symptom and implicate all those attending to the patient. Medicinal treatment has a more limited place in the fragile elderly patient, but its role remains to be assessed.

Aged↗
PubMed2003

Deactivation force-deflection behavior of multistranded stainless steel wires.

This investigation measured the deactivation (unloading) force-deflection behavior of selected multistranded stainless steel orthodontic wires. The guidelines from the revised American National Standards Institute/American Dental Association Specification No. 32 for orthodontic wires (type 2, nonlinear elasticity) were used to perform a 3-point bending test to obtain data for the deactivation force levels at 3, 2, 1, and 0.5 mm, and permanent deformation values. The study tested 20 wire designs: triple-stranded twisted wires, 5- and 6-stranded coaxial wires, and 8- and 9-stranded braided rectangular wires of selected cross-sections. Twenty specimens were tested for each wire design. The specification guidelines for testing provided a means for obtaining comparative unloading force delivery data for the deflections tested. Multistranded wires of significantly different cross-section, weave, and strand number fell within relatively narrow ranges of force delivery at the 0.5-mm (1.7-42.7 grams-force [gmf]) and 1-mm (31.1-134.2 gmf) deflections and wider ranges of force levels at the 2-mm (57.0-320.5 gmf) and 3-mm (72.5-451.8 gmf) deflections. All wires exhibited some permanent deformation, but none averaged greater than 0.66 mm. The testing also showed that multistranded wires of significantly different design exhibit similar force levels. The guidelines of the revised Specification No. 32 yielded deactivation data with regard to force delivery and provided comparisons of the wire designs tested.

Dental Alloys↗
PubMed1994

Elastic energy/stiffness ratios for selected orthodontic wires.

This investigation determined the ratio of the energy available for orthodontic tooth movement to the stiffness and flexibility of a given wire. Twenty-five specimens each of five brands of orthodontic wire were tested in tension in the as-received condition. Force versus elongation diagrams were obtained and then converted into stress-strain data. Mean values were determined for the yield strength and yield strain for each brand of wire. The modulus of elasticity (E), modulus of resilience (R), and elastic compliance (C) were then calculated. Two ratios were established by using the three mechanical properties: (1) the modulus of resilience/modulus of elasticity (R/E) ratio and (2) the modulus of resilience/elastic compliance (R/C) ratio. The results confirmed that the use of these two ratios in combination permitted one to differentiate among the various types of orthodontic wires, with respect to stored energy and its relationship to the stiffness or flexibility of the wire.

Analysis of Variance↗
PubMed1995

The correction of interarch malocclusions using a fixed force module.

This article describes the use of a flexible force module (the Jasper Jumper) that can be incorporated into existing fixed appliances to correct various types of sagittal malocclusion. Essentially the spring mechanism described in this article is a modification of the original bite jumping mechanism of Herbst. The flexible spring module provides greater freedom of mandibular movement than is possible with the more rigid mechanism of the Herbst appliance. The facial musculature applies force through these modules to the anchor points to produce a variety of treatment effects. The treatment effects produced by the module mimic those previously described for the Herbst appliance and include posterior movement of the maxillary buccal segments and anterior movement of the mandible or mandibular dentition or both. Specifics of the clinical management of this modular system are discussed, including anchorage preparation and torque application, as well as the methods of anchoring, activating and reactivating the modules.

Activator Appliances↗
PubMed1996

Differential scanning calorimetry (DSC) analyses of superelastic and nonsuperelastic nickel-titanium orthodontic wires.

The purpose of this study was to determine the transformation temperatures for the austenitic, martensitic, and rhombohedral (R) structure phases in representative as-received commercial nitinol (NiTi) orthodontic wire alloys, to reconcile discrepancies among recent publications. Specimens were examined by differential scanning calorimetry (DSC) over a temperature range from approximately -170 degrees C to 100 degrees C, with a scanning rate of 10 degrees C per minute. Two different pathways, with the intermediate R structure either absent or present, were observed for the transformation from martensitic to austenitic NiTi, whereas the reverse transformation from austenitic to martensitic NiTi always included the R structure. The enthalpy (delta H) for the transformation from martensite to austenite ranged from 0.3 to 3.5 calories per gram. The lowest delta H value for the nonsuperelastic Nitinol wire is consistent with a largely work-hardened, stable, martensitic microstructure in this product. The DSC results indicate that the transformation processes are broadly similar in superelastic, body-temperature shape-memory, and nonsuperelastic NiTi wires. Differences in bending properties for the NiTi orthodontic wires at room temperature and 37 degrees C are due to the relative proportions of the metallurgical phases in the microstructures.

Alloys↗
PubMed1996

Bracket angulation as a function of its length in the canine distal movement.

The slot angulations that are built into currently manufactured brackets are the same as those recommended more than 20 years ago. Because of a continuous trend toward miniaturization, the bracket slot length has diminished considerably, fact that should have had an impact on the characteristics of the slot. This impact has not yet taken place. A decrease in the overall bracket size and the shortening of the slot length invite unaccounted tooth rotation, which happens when an attempt is made to adhere to traditional angulations. If only a pure translation of a tooth is wanted, such a rotation becomes undesirable. To reduce its action, power arms are used. Unfortunately, these do not solve the problem. Indeed, to overcome this effect, a modification of the values of standard angulations is needed. To illustrate the point, maxillary canine retraction is considered, because it is both common and involves an already high bracket slot angulation. With standard solid mechanics and statics, new angulations are proposed as functions of the bracket slot length and arch wire rigidity. In addition, an estimation of the minimum useful size of the slot is made.

Alloys↗
PubMed1996

The effects of loops on the torsional stiffnesses of rectangular wires: an in vitro study.

Various loop designs have been investigated with respect to the increased torsional flexibility given to the wire by their inclusion. The torsional flexibility of the wire was shown to be enlarged from 26% to 63%, depending on loop design. Both variation in wire cross-section and loop geometry will influence torsional stiffness. Wires with small cross-sectional dimensions will show greater flexibility in torsion. Even small deviations from the stated cross-sectional dimensions can influence the change in torsional stiffness caused by a specific loop design. Inclusion of a reverse-closing loop led to the greatest increase in flexibility, while a Bull loop changed torsional stiffness the least. When vertical flexibility is needed along with reduced torsional stiffness, the T-loop is the loop of choice.

Analysis of Variance↗
PubMed1997

The effect of friction on the bending stiffness of orthodontic beams: a theoretical and in vitro study.

The purpose of this study was to investigate the effect of friction on the bending stiffness of orthodontic beams. A theoretical and experimental model have been established where tensile and compressive forces are applied to an arch wire to simulate the effect of additional friction during activation and deactivation, respectively. The results show that tensile force increases wire stiffness, and that compressive force increases flexibility. Thus more force will be needed during activation and more force will be lost during deactivation. The amount of force lost increases nearly linearly with increasing friction. During activation, the percentage increase in force due to friction for a given deflection is about equal to the loss of force due to friction during deactivation. Friction affects thin flexible wires more than heavy wires. Careful ligation is recommended in the leveling phase to reduce the negative side effects of friction.

Compressive Strength↗
PubMed1998

A formula for the displacement of an arch wire when subjected to a second-order couple.

A new formula, expressing the local angular displacement of an orthodontic beam when subjected to a second-order couple applied at midspan, has been developed and analyzed. The computed displacements were compared with the results of ex vivo testing. There was good agreement between the results from the theoretical evaluation and the bench testing. Second-order activation of an orthodontic beam can be described in four sequential phases. The initial displacement is influenced by the second-order clearance between bracket-slot and wire as well as the relationship between the bracket-slot width and interbracket distance. During phase II there is a nonlinear relationship between applied couple and rotational displacement. Within phases three and four displacement is linearly related to the interbracket distance, provided the relationship between the bracket-slot width and interbracket distance remains constant. For a given tooth size, the second-order beam stiffness is exponentially related to bracket width. The experiments also show that even small deflections of thin stainless steel wires can lead to second-order couples of large magnitudes when using a clinically relevant interbracket distance. Consequently, it is important that the orthodontist evaluates his or her choice of bracket width and arch wire stiffness in each clinical case in order to avoid supra-physiologic force levels.

Algorithms↗
PubMed1999

Effects of water immersion on mechanical properties of new esthetic orthodontic wire.

New fiber-reinforced plastic orthodontic wire (FRP wire) was fabricated with polymethyl methacrylate (PMMA) for the matrix and biocompatible CaO-P(2)O(5)-SiO(2)-Al(2)O(3) (CPSA) glass fibers for fibers that have not only high esthetics but also mechanical properties similar to those of metal wires. The purpose of this study was to evaluate the effects of water immersion on the mechanical properties of this new wire. The fiber-reinforced plastic orthodontic wire specimens were 0.5 mm in diameter with 29.1% to 60. 4% volume fraction of fibers that were 20 microm in diameter. A three-point flexural test was performed to obtain the elastic modulus and flexural load at the deflection of 1 mm under dry and wet conditions. Stress relaxation of the wires was tested under dry and wet conditions, and the wire diameters were measured before and at 20 days after immersion. The results showed that there were changes in the elastic modulus up until 10 days and in flexural load up until 20 days after immersion. The values of these two at 30 days after immersion were 93% and 87%, respectively, of those before immersion. Stress relaxation occurred rapidly from the start of immersion until about 60 minutes under dry conditions and about 120 minutes under wet conditions and then approached saturation. The swelling of hydrated fiber-reinforced plastic orthodontic wires affected the wire diameter, although this effect was not significant. The results of this study therefore suggest that the mechanical properties of fiber-reinforced plastic orthodontic wires are reduced by water immersion in the initial stage.

Dental Materials↗
PubMedDate not supplied

Electromyographic activity in stiff and normal elbows during elbow flexion and extension.

This prospective, controlled pilot study investigated electromyographic activity in elbow muscles during active elbow flexion and extension and during prolonged elbow extension with and without resistance. Biceps brachii, brachialis, brachioradialis, and triceps activity was measured in 10 subjects with elbow motion deficits after injury and in 10 controls. Surface electromyography was recorded during active elbow flexion, extension, and passively positioned elbow extension with and without 3 lb on the distal forearm. All muscles of the stiff elbow group had greater activity compared with controls during active elbow flexion and extension. Biceps brachii of the stiff group showed antagonist activity equivalent to agonist. For all other flexors in both groups, agonist activity was greater than antagonist. During prolonged extension, biceps brachii, unweighted, showed greater activity in the stiff group than in controls. Both groups showed greater flexor activity when weighted. Across time, activity was sustained or increased in all muscles in both groups.

Adult↗
PubMed1997

Flexible (Polyactive) versus rigid (hydroxyapatite) dental implants.

In a beagle dog study, the peri-implant bone changes around flexible (Polyactive) and rigid hydroxyapatite (HA) implants were investigated radiographically by quantitative digital subtraction analysis and by assessment of marginal bone height, with the aid of a computerized method. A loss of approximately 1 mm of marginal bone height was observed for both the dense Polyactive and the HA implants, after 6 months of loading. This value appeared to be stable from 12 weeks of loading onward. Along the total length of the implant during the first 6 weeks of loading, both the flexible (dense Polyactive) and the rigid (HA) implants showed a decrease in density. However, after this 6-week period, the bone density around the implants increased, and after 18 weeks the original bone density was reached. The flexible Polyactive implants provoked less decrease in density than the rigid HA implants, although not to a statistically significant level. This finding sustains the hypothesis that flexible implant materials may transfer stresses to the surrounding bone more favorably.

Alveolar Bone Loss↗
PubMed1997

Biomechanical evaluation of new fixation devices for mandibular angle fractures.

This biomechanical study investigated the effectiveness of fixation devices of simulated angle fractures in sheep mandibles. The fractures were stabilized by a Leibinger 8-hole three-dimensional (3-D) plate, a Synthes eight-hole mesh plate, and a Synthes six-hole reconstruction plate with 2.0-mm and 2.4-mm mono- and bicortical screws. Each mandible was tested in bending (class III cantilever model). The bone mineral density of the mandibles was measured by computed tomography scan. The Leibinger 3-D plate showed plate deformation in bending of > 230 N. None of the plates showed failure in the bone/screw interface. The gap and displacement values for the mesh and 3-D plate were comparable to those of the reconstruction plate. These results indicate that a 3-D or mesh plate can be used for fixation of mandibular angle fractures.

Animals↗
PubMed1999

Optimal length and angle of a new lightwand device (Trachlight).

STUDY OBJECTIVE: To investigate the effects of angle and length of the Trachlight lightwand and the effect of obesity on transillumination of the neck and difficulty of intubation. DESIGN: Prospective, randomized study. SETTING: Operating room of a university hospital. PATIENTS: 270 patients, aged 30 to 70 years, requiring anesthesia. INTERVENTION: Three different studies were performed. 1) One hundred twenty adults for general anesthesia to test the effect of the angle, 2) 120 patients for the length of the extrusion, and 3) 30 patients with body weight > or = 120% of the standard (Broca's formula) versus 30 with body weight < 120% of the standard to test the effect of the obesity. 1) The lightwand was bent at 20 degrees, 40 degrees, 60 degrees, or 80 degrees with 0 cm extruded from the endotracheal tube; 2) the lightwand was exposed from the endotracheal tube with -0.5, 0, 1, 2, 3, or 4 cm with 40 degrees angle; and 3) the effect of obesity was tested with 40 degrees angle and 0-cm extrusion. Endotracheal intubation was performed using the lightwand. Transillumination of the light at neck and the difficulty of intubation were assessed. MEASUREMENTS AND MAIN RESULTS: 1) A 20 degrees angle decreased the transillumination and an 80 degrees angle increased the number of difficult intubation. 2) Transillumination decreased with -0.5 cm and 0 cm extrusion. Difficult intubation increased with the extrusion > or = 3 cm. 3) Transillumination decreased and difficult intubation increased in the patients with body weight > or = 120% of the standard. CONCLUSIONS: To increase the success rate of tracheal intubation using the lightwand, the lightwand should be bent in 40 degrees to 60 degrees, with the extrusion of 1 to 2 cm from the tracheal tube. For obese patients with body weight > or = 120% of the standard, the lightwand was not useful.

Adult↗
PubMed2001

Melting and stone production using MSW incinerated ash.

Most of the municipal solid waste (MSW) in Japan is incinerated and the generated ash is landfilled. However, environmental pollution problems have increased and Japan has decreased final disposal sites for landfills. With the application of a melting system, the volume of incinerated ash can be reduced and the effective use of melted slag is being developed for use in civil engineering works. However, the low strength of melted slag as a vitreous structure has limited its effective use. As a solution for this deficiency, a technology to crystallize melted slag into higher strength produced stones was developed. With the joint cooperation of Chiba Prefecture and Kamagaya City, a demonstration plant for melting and stone production with a capacity of 4.8 tons of incinerator ash per day was constructed. The demonstration test was conducted from May 1998 to June 1999 with satisfactory results stated below. Long-term stable operation and performance of the plant have been confirmed and effective applications of produced stones have been demonstrated on a commercial scale. The results are as follows. 1. A stable, continuous operation and good quality produced stones have been confirmed by treating more than 750 tons of MSW incinerated ash. 2. More than 99.9% of dioxins contained in the incinerated ash were decomposed, and the concentration of dioxins in produced stones were less than the detection limit set by Japanese environmental standards. 3. Leaching values of hazardous heavy metals of produced stones sufficiently met the environmental standard on soil pollution of the Environment Agency with superior leaching behavior for the vitreous slag, thus confirming their safe applications. 4. The effective application of produced stones for aggregate was tested based on Japanese Industrial Standards and every figure of test results met the Japanese standard values. The use of produced stones as raw materials for permeable pavement blocks has been confirmed in commercial construction for a park in Chiba Prefecture. Asphalt use was also demonstrated by paving a commercial roadway in Kamagaya City.

Aluminum Oxide↗
PubMed2001

Matrix proteins from insect pliable cuticles: are they flexible and easily deformed?

Proteins from pliable cuticle of locusts, Schistocerca gregaria, and silk moth larvae, Hyalophora cecropia, were studied in solution by means of a fluorescent probe, 8-anilinonaphthalene-1-sulphonic acid (ANS), which is much more fluorescent in non-polar media than in polar media. An intense ANS-fluorescence was observed in the presence of the cuticular proteins at pH-values close to their acidic isoelectric points, and the fluorescence decreased markedly when pH was increased to neutrality or when small amounts of denaturants were added. Aggregation and eventual precipitation of both H. cecropia and locust proteins were obtained by addition of neutral salts, and the aggregation was accompanied by an increased ANS-fluorescence intensity. A decreased ANS-fluorescence was observed at salt concentrations too low to cause visible aggregation of the H. cecropia proteins, probably due to weakened electrostatic interactions between chain segments, but such a decrease was not observed for the locust proteins. The changes in intensity of ANS-fluorescence induced by addition of small amounts of denaturants or salts to solutions of the proteins indicate that more hydrophobic residues are exposed to the solvent, when either hydrophobic interactions or electrostatic attractions between chain segments are weakened. The result is a less compact protein structure, where fewer and smaller hydrophobic clusters are available for protecting ANS-molecules from the quenching effects of water. The effects of denaturants on ANS-fluorescence in the presence of the cuticular proteins are different from those observed for globular proteins, such as hen egg albumen, and the differences can be explained by the suggestion that the cuticular proteins do not have a precisely folded and densely packed hydrophobic core comparable to that present in native globular proteins, and that accordingly they do not undergo a process of denaturation corresponding to that of globular proteins. The behaviour of the cuticular proteins resembles that described for unordered, randomly coiled, thermally agitated polymer chains, whose hydrodynamic volumes depend upon the composition of the medium. It is proposed that the major part of the peptide chains of the cuticular proteins are in an unordered, random structure both when the proteins are in solution and when present in the intact cuticle; probably only the chain regions involved in binding the proteins to chitin will have a well-defined spatial organisation.

Anilino Naphthalenesulfonates↗
PubMed2002

Major histocompatibility complex class II binding characteristics of peptoid-peptide hybrids.

The major histocompatibility complex (MHC) class II binding requirements for solvent-exposed peptide residues were systematically studied using amino acid and peptoid substitutions. In a peptoid residue, the side chain is present on the backbone nitrogen atom as opposed to the alpha-carbon atom in an amino acid residue. To investigate the effect of this side chain shifting on MHC binding, three amino acids in the central part of the peptide sticking out of the binding groove were replaced by corresponding peptoid residues. Two peptoid-peptide hybrids showed large affinity decreases in the MHC-peptide binding assay. To investigate this affinity loss, the individual contributions to MHC binding affinity of the side chain (position), the putative hydrogen bond, and the flexibility were dissected. We conclude that the side chain position as well as the backbone nitrogen atom hydrogen bonding features of solvent-exposed residues in the peptide can be important for MHC binding affinity.

Amino Acid Sequence↗
PubMed2003

Synthesis and bioevaluation of glycosyl ureas as alpha-glucosidase inhibitors and their effect on mycobacterium.

Glycosyl amino esters (2-13) on reaction with different isocyanates resulted in quantitative conversion to glycosyl ureas (14--32). Few of the selected ureas (15-20, 22-28, 30 and 32) on cyclative amidation with DBU/TBAB/4 A MS gave respective dihydropyrimidinones in fair to good yields (33-47). The compounds were screened for alpha-glucosidase inhibitory activity and two (19 and 23) of them showed strong inhibition against rat intestinal alpha-glucosidase. The compounds were also screened against Mycobacterium aurum, however, only one (19) of them exhibited marginal antitubercular activity.

Animals↗