A Prosthetic Socket with Active Volume Compensation for Amputated Lower Limb.

Typically, the actual volume of the residual limb changes over time. This causes the prosthesis to not fit, and then pain and skin disease. In this study, a prosthetic socket was developed to compensate for the volume change of the residual limb. Using an inflatable air bladder, the proposed socket monitors the pressure in the socket and keeps the pressure distribution uniform and constant while walking. The socket has three air bladders on anterior and posterior tibia areas, a latching type 3-way pneumatic valve and a portable control device. In the paper, the mechanical properties of the air bladder were investigated, and the electromagnetic analysis was performed to design the pneumatic valve. The controller is based on a hysteresis control algorithm with a closed loop, which keeps the pressure in the socket close to the initial set point over a long period of time. In experiments, the proposed prosthesis was tested through the gait simulator that can imitate a human's gait cycle. The active volume compensation of the socket was successfully verified during repetitive gait cycle using the weight loads of 50, 70, and 90 kg and the residual limb model with a variety of volumes. It was confirmed that the pressure of the residual limb recovered to the initial state through the active control. The pressure inside the socket had a steady state error of less than 0.75% even if the volume of the residual limb was changed from -7% to +7%.

Dynamic simulation of the self-tapping insertion process of orthodontic microimplants into cortical bone with a 3-dimensional finite element method.

INTRODUCTION: The aim of this study was to evaluate the stress state in the cortical bone around an orthodontic microimplant during and after the insertion surgery. METHODS: The self-tapping insertion of an orthodontic microimplant into 1-mm-thick cortical bone containing a predrilled hole was simulated by using a 3-dimensional finite element method. The entire insertion surgery was replicated by a total of 3601 calculation steps: ie, the first 3600 dynamic steps analyzing the insertion process and an additional static step for analyzing the residual stress state after insertion. Four microimplants were experimentally inserted into rabbit tibiae to measure the insertion torques and compare them with the finite element analysis results. RESULTS: Reasonable agreement was observed between the experimentally measured and the finite element calculated torques, confirming the validity of our finite element simulation, which showed that high stresses can develop in the interfacial bone during microimplant insertion. Hoop stresses above the ultimate tensile strength and radial stresses above the ultimate compressive strength of cortical bone developed in the bone. Furthermore, residual radial stresses higher than the critical threshold stress to trigger pathologic bone resorption were observed after insertion. These high insertion-related stresses implied that it is not the orthodontic force or the timing of its application, but the insertion conditions that can determine the bone's response to the microimplant and its clinical prognosis. CONCLUSIONS: This in-vitro finite element analysis showed that, during the self-tapping insertion of orthodontic microimplants, stresses high enough to fracture cortical bone can develop. After the self-tapping insertion, the radial stresses calculated at the interfacial bone were higher than the threshold value to trigger pathologic bone resorption.

Factors affecting the clinical success of screw implants used as orthodontic anchorage.

INTRODUCTION: The purposes of this study were to examine the success rates and find factors affecting the clinical success of screw implants used as orthodontic anchorage. METHODS: Eighty-seven consecutive patients (35 male, 52 female; mean age, 15.5 years) with a total of 227 screw implants of 4 types were examined. Success rates during a 15-month period of force application were determined according to 18 clinical variables. RESULTS: The overall success rate was 91.6%. The clinical variables of screw-implant factors (type, diameter, and length), local host factors (occlusogingival positioning), and management factors (angle of placement, onset and method of force application, ligature wire extension, exposure of screw head, and oral hygiene) did not show any statistical differences in success rates. General host factors (age, sex) had no statistical significance. Mobility, jaw (maxilla or mandible), and side of placement (right or left), and inflammation showed significant differences in success rates. Mobility, the right side of the jaw, and the mandible were the relative risk factors in the logistic regression analysis when excluding mobility, inflammation around the screw implants was added to the risk factors. CONCLUSIONS: To minimize the failure of screw implants, inflammation around the implant must be controlled, especially for screws placed in the right side of the mandible.

Nonextraction treatment of an open bite with microscrew implant anchorage.

A 16-year-old girl with an anterior open bite was treated with nonextraction therapy that included intrusion of the maxillary and mandibular posterior teeth with microscrew implants. Implants (diameter, 1.2 mm; length, 8 or 6 mm) were placed into alveolar bone near the posterior teeth and used as anchorage for intrusive force. To prevent adverse side effects of buccoversion or linguoversion of the posterior teeth during intrusion, a transpalatal bar and a lingual arch were placed. The 3-mm anterior open bite was corrected in 11 months of treatment, after intrusion of the maxillary and mandibular posterior teeth and autorotation of the mandible. The posterior intrusion relapsed in the early stage of retention, at 8 months; thereafter, no obvious relapse was evident in the vertical position of the molars and the FMA. The treatment mechanics of anterior open bite with posterior intrusion by using microscrew implants were effective but still require a proper retention protocol.

Acid resistance of erbium-doped yttrium aluminum garnet laser-treated and phosphoric acid-etched enamels.

OBJECTIVE: To compare the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser ablation and of phosphoric acid etching on the in vitro acid resistance of bovine enamel. MATERIALS AND METHODS: Teeth were polished to make the surface flat. The polished enamel was either etched with 37% phosphoric acid for 30 seconds or ablated with a single 33 J/cm2 pulse from an Er:YAG laser. The control specimens were free from acid etching and laser ablation. Changes in crystal structure, dissolved mineral (calcium [Ca] and phosphorus [P]) contents, and calcium distribution in the enamel subsurface after a pH-cycling process were evaluated. RESULTS: After laser treatment, poor crystal structures improved without forming any new phases, such as tricalcium phosphates. Among the tested enamels, dissolved mineral contents were significantly different (P < .05). Er:YAG laser-treated enamels had the lowest mineral dissolution (Ca, 13.78 ppm; P, 6.33 ppm), whereas phosphoric acid-etched enamels had the highest (Ca, 15.90 ppm; P, 7.33 ppm). The reduction rate and reduced depth of calcium content along the subsurface were lowest in Er:YAG laser-treated enamels. CONCLUSION: The Er:YAG laser-treated enamels are more acid resistant to acid attack than phosphoric acid-etched enamels.

Effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic bracket retention.

The purpose of this study was to test the effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic treatment. Bovine incisors were either acid-etched or laser-treated. An orthodontic bracket was attached on each treated surface using one-step dentin adhesive and self-curing resin. Tensile bond strength was then evaluated. In addition, the surface morphology of specimens treated with phosphoric acid/laser and self-etching primer, as well as the cross-section of enamel-primer-resin interfaces, were observed. One-Up Bond F-treated specimens after Er:YAG laser ablation showed statistically similar tensile bond strength (9.9 +/- 1.3 MPa) to that of phosphoric acid-etched specimens (11.8 +/- 1.7 MPa). Surface roughness and thickness of the enamel-primer-resin interfaces did not much affect the tensile bond strength of the tested specimens. In conclusion, Er:YAG laser ablation achieved clinically acceptable level of tensile bond strength when used with One-Up Bond F.

Group distal movement of teeth using microscrew implant anchorage.

The purpose of this study was to quantify the treatment effects of distalization of the maxillary and mandibular molars using microscrew implants. The success rate and clinical considerations in the use of the microscrew implants were also evaluated. Thirteen patients who had undergone distalization of the posterior teeth using forces applied against microscrew implants were selected. Among them, 11 patients had mandibular microscrew implants and four patients had maxillary implants, including two patients who had both maxillary and mandibular ones at the same time. The maxillary first premolar and first molars showed significant distal movement, with no significant distal movement of the anterior teeth. The mandibular first premolar and first and second molars showed significant distal movement, but no significant movement of the mandibular incisor was observed. The microscrew implant success rate was 90% over a mean application period of 12.3 +/- 5.7 months. The results might support the use of the microscrew implants as an anchorage for group distal movement of the teeth.

Microscrew implant anchorage sliding mechanics.

AIM: To show the effectiveness of sliding mechanics used with microscrew implants in managing a dentoalveolar protrusion. There are several advantages, including reduced treatment time, simplified treatment mechanics, early profile changes, and elimination of interarch mechanics. MATERIAL AND METHODS: A step-by-step procedure for microscrew implant anchorage sliding mechanics is shown, with records of treated patients, which demonstrate the aforementioned advantages of this technique. The associated biomechanics and theoretical explanation follow. RESULTS: The authors show how the microscrew implant can provide anchorage for en masse retraction of six anterior teeth and the efficiency and ease of the mechanics in managing a dentoalveolar protrusion. CONCLUSION: The microscrew implant offers orthodontic clinicians a minimally intrusive method of intra-arch anchorage that can retract the anterior teeth without the anchorage loss that is expected in conventional techniques. Sliding mechanics used with microscrew implants is shown to be simple and efficient.

Nd:YAG laser ablation and acid resistance of enamel.

The acid resistance of Nd:YAG laser-ablated enamel surfaces was studied by evaluating crystal structure, mineral distribution, and fluorescence radiance and image in the present study. For comparison, 37% phosphoric acid etching was performed. The formation of beta-tricalcium phosphate (beta-TCP) was confirmed in the laser-ablated surface. The Ca/P ratio increased after ablation due to mineral re-distribution. In contrast, the Ca/P ratio decreased after acid etching due to mineral loss. The laser-ablated enamels showed a smaller increase of fluorescence radiances and less clear laser confocal scanning microscope images than those observed in the acid-etched enamels. The former suggests a minimized mineral loss. The Nd:YAG laser irradiation will enhance the acid resistance and retard the carious progression in enamel.

Nd:YAG laser ablation of enamel for orthodontic use: tensile bond strength and surface modification.

To test the feasibility of Nd:YAG laser ablation for orthodontic use, bovine enamels were ablated at 2.5 and 3.5 W/pulse conditions. Orthodontic brackets were attached on the ablated enamel surface using a self-curing resin. For comparison, a 37% phosphoric acid solution was used to etch the enamel surface. The strength to detach the brackets was estimated for both surface treatments. Modifications of the enamel surfaces were also compared using a scanning electron microscope for both treatments. The tensile bond strengths from the laser-ablated enamels were significantly lower than that from the phosphoric acid-etched enamels. The higher laser power treatment gave a significantly higher bond strength average than with the lower laser power. The laser-ablated surfaces showed the formation of craters. The formation involved melting and solidification of enamel. Each crater had numerous micropores. Microscopically, the ablated surface was smooth, while much of the acid-etched surface contained numerous microspaces.

Changes in longitudinal craniofacial growth in subjects with normal occlusions using the Ricketts analysis.

OBJECTIVE: This study was designed to define the Korean norm values for the Ricketts analysis. METHODS: In this longitudinal study, lateral cephalograms of 31 subjects with normal occlusion were taken biennially from ages 9-19 years. Cephalometric measurements were performed. Parameters for which the 10-year change did not exceed one standard deviation were defined as unchanged. The means and standard deviations for the measured parameters were determined for each age group. RESULTS: No significant changes in growth were observed in the molar relationship, incisor overjet, incisor overbite, mandibular incisor extrusion, interincisor angle, lower incisor tip (B1) to A point-Pogonion (A-PO) plane, upper incisor tip (A1) to A-PO plane, B1 inclination to A-PO, A1 inclination to A-PO, B1 inclination to Frankfurt plane (FH), convexity, lower facial height, facial axis, maxillary depth, maxillary height, palatal plane to FH, cranial deflection, ramus Xi position, or porion location. Continual changes over the 10 years of growth were observed in the maxillary first molar distal position to pterygoid true vertical plane, facial depth, mandibular plane to FH, anterior cranial length, mandibular arc, and corpus length. CONCLUSIONS: Clinicians can apply the Korean norms at age 9 as determined in this study when using the Ricketts analysis. The patient's age at the beginning of treatment and their sex should be taken into consideration when drawing visual treatment objectives.

Treatment of open bite with microscrew implant anchorage.

Open bite treatment with microscrew implant anchorage is discussed in relation to vertical control of the posterior dentoalvelar dimension. Maxillary microscrew implants provided anchorage for intruding the posterior teeth and retracting the anterior teeth; mandibular microscrew implants were used to apply intrusion force distal to the mandibular first molars to prevent mesial tipping of the posterior teeth during space closure. Closing the mandibular plane after intruding the maxillary posterior teeth and bodily mesial movement of the mandibular posterior teeth contributed to facial profile improvement. The efficacy and potency of microscrew implants in open bite treatment are discussed.