Adhesive Bridges Research Articles

Forces between colloid particles in natural waters.

The origin and nature of interparticle forces acting on colloid surfaces in natural waters has been examined using an atomic force microscope. Natural colloids were represented by a surface film of iron oxide precipitated onto spherical SiO2 particles, and the effects of adsorbed natural organic matter (NOM), solution pH, and ionic composition on the force-separation curves were investigated. NOM from both riverine and marine environments was strongly adsorbed to the iron oxide surface. Under conditions of low ionic strength, the interparticle forces were dominated by electrostatic repulsion arising from negative functional groups on the NOM, except at very small separations (<10 nm) where repulsive forces arising from steric interference of the NOM molecules were also present. At high ionic strength (e.g., seawater) or low pH, the electrostatic forces were largely absent, allowing steric repulsion forces to dominate. In addition, adhesive bridging between surfaces by adsorbed NOM was observed, creating a strong energy barrier to spontaneous disaggregation of colloid aggregates. Our results demonstrate that adsorbed NOM dominates the surface forces and thus stability with respect to aggregation of natural water colloids.

A Case Report of Adhesion Bridge Applied to Maxillary Canine Defect

A Case Report of Adhesion Bridge Applied to Maxillary Canine Defect

Peeling process in living cell movement under shear flow.

We present a direct optical observation of the behavior of the contact area between a living cell (Dictyostelium discoideum) and a solid substrate under shear flow. It is shown that the membrane is peeled off the substrate. The relationship between the peeling velocity and the applied force is obtained experimentally and explained from the behavior of individual adhesion bridges. The dissipation occurring during the peeling process is explicitly calculated in terms of out-of-equilibrium thermodynamics.

Peeling model for cell detachment.

In many experimental situations, the adhesion of cells to solid substrates is due to non-covalent chemical bonds. It is the thesis of this paper that many phenomena occurring in cell detachment experiments, such as in I (E. Decavé, G. Garriver, Y. Brechet, B. Fourcade, F. Bruckert, Biophys. J. 82, 2383 (2002)), result from the static and dynamic properties of the adhesive bridges at the extreme margin of the cell. This region defines the adhesive belt where the distribution of connected bonds crosses over to zero where the membrane leaves the substrate. The theoretical model we introduce in this paper discusses the threshold force together with the peeling velocity in the same theoretical framework. In this one-dimensional model, the threshold force results from a non-homogeneous distribution of anchor proteins along the membrane so that the adhesive belt increases its capacity to resist motion with increasing the external force. Analyzing the kinetics of the the contact line motion, we derive the characteristic relationship speed versus external force and we describe the non-equilibrium state of the adhesive belt as a function of the speed. We discuss our model in view of the experimental results obtained with D. discoideum for hydrodynamic shear experiments. Our results could be also confronted to single-cell observations.

Shear Flow-Induced Detachment Kinetics of Dictyostelium discoideum Cells from Solid Substrate

Using Dictyostelium discoideum as a model organism of specific and nonspecific adhesion, we studied the kinetics of shear flow-induced cell detachment. For a given cell, detachment occurs for values of the applied hydrodynamic stress above a threshold. Cells are removed from the substrate with an apparent first-order rate constant that strongly depends on the applied stress. The threshold stress depends on cell size and physicochemical properties of the substrate, but is not affected by depolymerization of the actin and tubulin cytoskeleton. In contrast, the kinetics of cell detachment is almost independent of cell size, but is strongly affected by a modification of the substrate and the presence of an intact actin cytoskeleton. These results are interpreted in the framework of a peeling model. The threshold stress and the cell-detachment rate measure the local equilibrium energy and the dissociation rate constant of the adhesion bridges, respectively.

Non-equilibrium interaction forces between adsorbed polymer layers

The non-equilibrium forces of interaction between an 11 µm radius sphere of zirconia and a flat polished zirconia plate in the presence of adsorbed polyvinyl pyrrolidone (Mw= 40 000) have been investigated. The force–distance data were collected using an atomic force microscope (AFM) configured to operate as a force balance. Specific effects related to the velocity at which the surfaces were brought together and separated were observed. For the compression cycles the energy of interaction at any given interaction distance was seen to be higher at a higher rate of collision. These effects are explained from a consideration of polymer relaxation times and increased effective rigidity of the chains at higher scan rates causing the increased repulsive behaviour. For the decompression cycles, a longer time of contact between the surfaces before decompression was seen to lead to the formation of bridging interactions. Faster scan rates which led to shorter surface contact times resulted in the absence of any energy minima indicative of adhesive bridging links.

Reconsideration of the Adhesion Bridge

Reconsideration of the Adhesion Bridge

Status of adhesion bridge

Status of adhesion bridge

Resin‐retained bridges in the treatment of traumatized dentition*

Resin-retained bridges can be used as the definitive treatment, as well as for interim treatment. Compared with conventional fixed prostheses, there are some advantages which make this treatment especially useful in traumatized dentition. The ultra conservative approach makes the adhesive bridge a standard treatment option in cases of uncertain prognostic factors. However, in such specific situations as traumatized dentition some complicating factors may be present. These complicating factors must be recognized and eliminated to create situations in which this kind of restoration can be successful. Therapeutic and patient-related factors are discussed using data from longitudinal clinical studies. Available clinical information indicates the anterior adhesive bridge to a 'permanent restoration'. However, a benefit-cost analysis is necessary to weigh the value of this restorations.

Application of Adhesion Bridge on Practical Use

Application of Adhesion Bridge on Practical Use

A method to compare cost‐effectiveness of dental treatments: adhesive bridges compared to conventional bridges

The cost-effectiveness of a dental restoration depends primarily on the durability and the cost of the restoration. In this report a method is described to compare the cost-effectiveness using the durability data of adhesive bridges and conventional bridges. The study shows that, for the situation in the Netherlands, the breakeven point for equal cost-effectiveness compared to conventional bridges is achieved when the 50% survival for adhesive bridges is approximately 6.5 yr. Clinical data indicate a higher cost-effectiveness for anterior adhesive bridges. The method described in this report is considered to be useful for comparing cost-effectiveness of dental restorations in different situations.

Performance of 400 adhesive bridges fitted in a restorative dentistry department

The purpose was to present a descriptive report of the clinical performance of adhesive bridges fitted in a university department of restorative dentistry. The case records of 400 consecutive adhesive bridges fitted between November 1984 and June 1989 in the School of Clinical Dentistry, Queen's University, Belfast were reviewed. The majority of the bridges (66 per cent) were of a fixed-fixed Maryland design; the remainder were Maryland cantilevers (18 per cent), hybrids, i.e. Maryland cantilevers which slotted into conventional units (8 per cent), and Rochette bridges (6 per cent). The mean duration of clinical service at review was 2.7 years. One hundred (25 per cent) of the bridges debonded on at least one occasion. Of the bridges which debonded the average number of debonds was 1.7, with the first debond happening on average 10.7 months after placement (range 1-42 months). Fifty-seven (14 per cent) debonded on one occasion only; 25 (6 per cent) debonded twice and 18 (5 per cent) debonded on three or four occasions. The length of clinical service was a significant factor in relation to debonding. A lower proportion of posterior than anterior bridges debonded and cantilevered and hybrid designs performed well. It is concluded that this investigation confirms the efficacy of resin-bonded bridgework used to replace both anterior and posterior teeth.

Treatment of Traumatic Dental Injuries: Shift in Strategy

A more conservative approach to the treatment of traumatic dental injuries has been made possible by knowledge concerning the pathogenesis of external root resorption, increased knowledge about wound healing processes in the pulp and periodontium, as well as by advances in restorative dentistry (reattachment of crown fragments with a dentin bonding system, the use of adhesive bridges, and advances in autotransplantation and implantation). However, a rethinking by the public, clinicians, and third-party payers is necessary for these procedures to gain wider acceptance. The present article describes the state of the art of treating dental trauma in the hope that these advances can become an accepted part of the dental trauma armamentarium and not merely scientific curiosities.

接着性補綴物の維持力に関する研究 特に臨床的視点から

Although the prognoses of the adhesive bridges are practically satisfactory, some disconnections have been reported. Physical bite, twisting and tearing forces are considered to be the causes for these disconnections. Paired natural human teeth; 2 incisal and 2 molar teeth, were embedded in cold cured resin for fatigue test and axial reduction was slightly performed. Cast bridges which were designed to come to 30 mm2 in every abutment and to resemble clinical design, were made from two kinds of metal; Ni-Cr alloy and Ag-Pd-Au alloy, and adhered with teeth by Panavia EX (Kurarey Co. Ltd.). Incisal bridges were disconnected easier than molar bridges in the fatigue test. There was no significant difference between 2 kinds of metal. With stereoscopic microscope, cohesive fracture of resin was observed on the region which was farthest from supporting point of fatigue force in incisal bridges. Dimple patterns characteristically in fatigue fracture were also observed in some cases. In modified tensile test of incisal teeth using Ni-Cr alloy, force point was given far 1 mm & 12 mm apart from approximal surface, and various twisting and tearing forces were loaded in 12 mm cases. The cases loaded by higher twisting and tearing forces had significantly smaller bond strength.

High strength Ag-Pd-Cu alloys

Twelve kinds of Ag-Pd-Cu alloy, containing 25, 30, 35, 40 wt% Pd, 20, 25, 30 wt% Cu and the residual quantity 30-55 wt% Ag were melted in an argon atmosphere. These alloys were cast using dental precision casting, subsequently, softening heat treatment (water quenching from 800 degrees C) and hardening heat treatment (450-250 degrees C oven cooling) were applied. After softening heat treatment, the Vickers hardness, tensile strength, and elongation of the experimental alloys ranged from 145 to 200, from 41 to 60 kgf/mm2 and from 11 to 27%, respectively. Therefore, these alloys were very ductile in softening heat treatment condition. After hardening heat treatment, the Vickers hardness of the alloys increased in the range of 241-433 and tensile strength increased in the range of 73-107 kgf/mm2. However, elongation decreased to 0.5-3.5%. Composition of the alloy that had the maximum tensile strength (104 kgf/mm2) was about 45 Ag-35 Pd-20 Cu. Brightness (L*) of the test pieces that were immersed in 0.1% sodium sulfide solution of 37 degrees C for 3 days ranged from 58 to 67. After hardening heat treatment, the Ag-Pd-Cu ternary alloy containing 20-30% Cu, 30-40% Pd had satisfactory high hardness and strength for adhesion bridge, but their elongation and tarnishing resistance were insufficient for clinical application.

Prognostic observation on the prosthesis using adhesive resin

Over 200 prosthesis using adhesive resin have been set for three years from 1982 to 1985 in our clinic.The patients were recalled and investigated the prognosis of them.The following results were obtained:1. Adhesion bridges accounted for more than 80% among them and number of posterior bridges has been increased in every year.2. Adhesion splints have been mainly used for periodontal splints and permanent fixation after orthodontic treatment.3. The successful rate of posterior bridges was better than that of anterior bridges.4. The successful rate of adhesion splints was not so better than adhesion bridges.

Treatment times for adhesive bridges

The aim of this study was to collect information about the mean working time needed to accomplish the clinical procedures in applying an adhesive bridge, and to gain an insight into the factors that influence the working time. The study was carried out as part of a clinical trial. One hundred and fifty-one patients needing one adhesive bridge were selected for this study and divided between five operators. Clinical procedures were carried out following a written protocol. The statistical method consisted of an ANOVA after log-transformation of the working times. The total mean working time needed to accomplish the clinical procedures for adhesive bridges was 60.7 min (s.d. +/- 16.5 min). The mean working time increased by 30% where the abutment teeth were restored with class II or class III restorations. No influence was found related to: type of bridge (i.e. macromechanical versus micromechanical), type of luting resin and location of the bridge. A significant effect on the working times was found for: operator, tooth preparation and occlusal adjustments. With increasing experience of the operator the median working time decreased by up to 35%. The data from this study are considered as useful basic information for efficient planning in the dental practice and for a further cost-benefit analysis.

Properties and adhesive strength of trial gold alloy for an adhesion bridge and an adhesion splint

Because the retainers of an adhesion bridge are adhered to the lingual and a part of the proximal tooth surface with an adhesive resin, metal for the retainer necessiates the mechanical properties which are endurable of occlusal force even if it is thin. It is suspected that an adhesion bridge made of type IV gold alloy, which has been used conventionally for crowns and bridges, results in the insufficient longevity of placement because of the shortage of its toughness.In this study we examined the mechanical properties and adhesive strength of the trial gold alloy we developed recently, whose hardness is higher than type IV gold alloy. Panavia EX® was used as an adhesive resin.We obtained the result that the trial gold alloy has greater properties in elastic modulus, proof stress and fatigue strength than type IV gold alloy and other dental gold alloys.Therefore, it is expected that the trial gold alloy has excellent rigidity as retainer metal for an adhesion bridge even if it is thin.

A clinical study on adhesion bridge and tooth movement

A clinical study on adhesion bridge and tooth movement

Mechanical analysis on design parameters of adhesion bridge. Part 3. Adhesive strength of adhesion bridge under shearing loads

This study was done to evaluate the thickness and shape of metal frameworks affectingthe adhesive strength of adhesion bridges under shearing loads.Experimental and numerical models for the pseudo-three dimensional finite element methodwere examined.The following results were obtained;1. Adhesive strength of metal frameworks under shearing loads was nearly equal when thethickness was 0.55 mm or more.2. Proximal extention of the metal framework was the most resistant shape under shearingloads.3. Dimples of pontic side made in the abutment surface could help increasing the resistanceunder shearing loads.4. The results of the experiments and the analysis of the pseudo-three dimensional finiteelement method were approximately equal.5. The adhesive strength under shearing loads was considerably lower when a loose toothwas supposed as the abutment tooth.