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The aim of this study is to develop a titanium three-dimensional (3D) printing novel hybrid suture anchor (HSA) with wing structure mechanism which can be opened to provide better holding power for surrounding osteoporotic bone. A screw-type anchor (5.5-mm diameter and 16-mm length) was designed with wing mechanism as well as micro dual-thread in the outer cortex bone contact area and macro single-thread in the anchor body. Both side wings can be opened by an internal screw to provide better bone holding power. The suture anchor and internal screw were manufactured using Ti6Al4V 3D printing and traditional machining, respectively. Static pullout and after dynamic 300-cyclic load (150 N) pullout tests for HSA with or without the wing open and commercial solid anchor (CSA) were performed (n = 5) in severely osteoporotic bone and osteoporotic bone to evaluate failure strengths. Comparison of histomorphometrical evaluation was performed through in vivo pig implantation of HSAs with the wing open and CSAs. The failure strengths of HSA with or without the wing open were 2.50/1.95- and 2.46/2.17-fold higher than those of CSA for static and after dynamic load pullout tests in severely osteoporotic bone, respectively. Corresponding values for static and after dynamic load pullout tests were 1.81/1.54- and 1.77/1.62-fold in osteoporotic bone, respectively. Histomorphometrical evaluation revealed that the effects of new bone ingrowth along the anchor contour for CSA and HSA were both approximately 20% with no significant difference. A novel HSA with wing mechanism was developed using 3D printing and the opened wing mechanism can be used to increase bone holding power for osteoporosis when necessary. Better failure strength of HSA than CSA under static and after dynamic load pullout tests and equivalence of bone ingrowth along the anchor contours confirmed the feasibility of the novel HSA.

Quality of medical services is even more critical than ever in a highly competitive health care industry. Long waiting time is a major source of patient dissatisfaction, thus, the issue of how to reduce waiting time to improve service quality is very important. A well-designed appointment scheduling system can effectively shorten the patient waiting time and enhance their satisfaction. This study aims to propose a framework for individualized outpatient appointment scheduling (OAS) in a dental clinic which composed of one attending dentist and two resident dentists. To design the OAS, firstly, the prediction model of the treatment duration of an individual patient was established by using artificial neural network. Secondly, discrete event simulation method was used to develop the simulation model which simulates the operations of the studied dental clinic. Finally, the established simulation model was used to evaluate the performance of the appointment scheduling. The proposed model consists of numbers of main features: 1) the service providers composed of multiple dentists with different professional competence levels; 2) there are two types of patients (return and not-return patients); 3) patient no-shows was considered; and 4) a variety of medical treatments (requiring different treatment time) are provided to the patients. The results of the study show that the proposed OAS can effectively improve the service performance of the dental clinic, this could be caused by patient’s characteristics were taken into consideration of building an appropriated appointment interval.

Low soil strength and high ground water level are the geotechnical engineering characteristics of the soil deposit in Taipei urban area. The railway underground project of Taiwan Railway Administration (hereinafter called the “TRA”)/Taiwan High Speed Railway (hereinafter called the “THSR”) is majorly constructed in congested metropolitan area with high density building and limited space. The key issue is to ensure the security of existing railway operation and to protect the buildings close to the construction site with soft soil condition. This article makes a summary about the design and construction feature for the Nangang extension of the railway underground project in Taipei city. Design features include pile foundation, underpinning slab and temporary supporting posts to withstand the loading of temporary tracks and platforms, ground improvement to increase the strength of soil to ensure the stability of 20 m deep excavation and bearing capacity of cut & cover tunnel with the condition of soil strength Su = 2 t/m2 and groundwater level about 1 m below ground level. Construction features include the removal schedule of existing tunnel and station, new tunnel and station construction process, risk management, safety monitoring system of deep excavation, and control of construction vibration and noise. Prevention design concept that reduce risk and ensure continuous operations of the TRA in the construction process of the project can be adopted as a reference in similar case for future engineers.

Reverse logistics is an important research area of particular interest to the academic community in recent years due to the impact of economics and environmental statutes. Reverse logistics deals with the processes associated with the reverse stream from owner to re-users. It encompasses all of the logistical activities from products no longer required by users to render those products usable in a market. Remanufacturing is one of the reverse logistical processes that could save substantial production costs. This study investigated a hybrid system involving manufacturing and remanufacturing processes. A constant demand can be satisfied by differentiated brand-new and remanufactured products. The used products are returned and remanufactured. We developed a mathematic model to analyze the economic decisions in pricing brand-new and remanufactured products.

Introduction This study evaluated the risk of failure for an endodontically treated premolar with different crack depths, which was shearing toward the pulp chamber and was restored by using 3 different computer-aided design/computer-aided manufacturing ceramic restoration configurations. Methods Three 3-dimensional finite element models designed with computer-aided design/computer-aided manufacturing ceramic onlay, endocrown, and conventional crown restorations were constructed to perform simulations. The Weibull function was incorporated with finite element analysis to calculate the long-term failure probability relative to different load conditions. Results The results indicated that the stress values on the enamel, dentin, and luting cement for endocrown restorations exhibited the lowest values relative to the other 2 restoration methods. Weibull analysis revealed that the overall failure probabilities in a shallow cracked premolar were 27%, 2%, and 1% for the onlay, endocrown, and conventional crown restorations, respectively, in the normal occlusal condition. The corresponding values were 70%, 10%, and 2% for the depth cracked premolar. Conclusions This numeric investigation suggests that the endocrown provides sufficient fracture resistance only in a shallow cracked premolar with endodontic treatment. The conventional crown treatment can immobilize the premolar for different cracked depths with lower failure risk.

This study integrates cone-beam computed tomography (CBCT)/laser scan image superposition, computer-aided design (CAD) and rapid prototyping (RP) technologies to develop a simplified and accurate technique for producing customized orthodontic mini-screw surgical templates. Maxillary bone solid models with the bone and teeth reconstructed using CBCT images and teeth and mucosa outer profile acquired using laser scanning were superimposed to allow mini-screw visual insertion planning and permit surgical template fabrication. The customized surgical template CAD model was fabricated offset based on the teeth/mucosa/bracket contour profiles in the superimposition model and exported to duplicate the plastic template using the rapid prototyping technique. An anterior retraction and intrusion clinical test for the maxillary canines/incisors showed that two mini-screws were placed safely and did not produce inflammation or other discomfort symptoms one week after surgery. The fitness between the mucosa and template indicated that the average gap sizes were found smaller than 0.5mm and confirmed that the surgical template presented good holding power and well-fitting adaption. This study addressed integrating CBCT and laser scan image superposition, CAD and RP techniques can be applied to fabricate an accurate customized surgical template for orthodontic mini-screws.

This study investigates the micro-mechanical behavior associated with enamel damage at an enamel/adhesive interface for different bracket bases subjected to various detachment forces using 3-D finite element (FE) sub-modeling analysis. Two FE macro-models using triangular and square bracket bases subjected to shear, tensile and torsional de-bonding forces were established using μCT images. Six enamel/adhesive interface sub-models with micro- resin tag morphology and enamel rod arrangement were constructed at the corresponding stress concentrations in macro-model results. The boundary conditions for the sub-models were determined from the macro-model results and applied in sub-modeling analysis. The enamel and resin cement stress concentrations for triangular and square bases were observed at the adhesive bottom towards the occlusal surface under shear force and at the mesial and distal side planes under tensile force. The corresponding areas under torsional force were at the three corners of the adhesive for the triangular base and at the adhesive bottom toward/off the occlusal surface for the square base. In the sub-model analysis, the concentration regions were at the resin tag base and in the region around the etched holes in the enamel. These were perfectly consistent with morphological observations in a parallel in vitro bracket detachment experiment. The critical de-bonding forces damaging the enamel for the square base were lower than those of the triangular base for all detached forces. This study establishes that FE sub-modeling can be used to simulate the stress pattern at the micro-scale enamel/adhesive interface, suggesting that a square base bracket might be better than a triangular bracket. A de-bonding shear force can detach a bracket more easily than any other force with a lower risk of enamel loss.

A semiconductor foundry is essentially a make-to-order (MTO) factory. Yet, in a low-demand season, it may enter into a hybrid business model—producing make-to-stock (MTS) as well as MTO products to maintain high utilization of machines. This research proposes a scheduling method for such a hybrid MTO/MTS system with machine-dedication characteristics, a constraint imposed on the process route caused by the advance of manufacturing technology. The scheduling method aims to achieve a high on-time delivery rate for MTO products as well as a high throughput for MTS products. Simulation experiments show that the proposed scheduling method outperforms representative methods in the literature.

The aim of this study was to determine the relative contribution of changes (design factors) in implant system, position, bone classification, and loading condition on the biomechanical response of a single-unit implant-supported restoration. Non-linear finite-element analysis was used to simulate the mechanical responses in an implant placed in the maxillary posterior region. The Taguchi method was employed to identify the significance of each design factor in controlling the strain/stress. Increased strain values were noted in the cortical bone with lateral force and an implant with a retaining-screw connection. Cancellous bone strain was affected primarily by bone type and increased with decreasing bone density. Implant stress was influenced mainly by implant type and position. The combined use of finite-element analysis and the Taguchi method facilitated effective evaluation of the mechanical characteristics of a single-unit implant-supported restoration. Implants placed along the axis of loading exhibit improved stress/strain distribution. The reduction of lateral stress through implant placement and selective occlusal adjustment is recommended. An implant with a tapered interference fit connection performed better as a force-transmission mechanism than other configurations.

Objectives This study investigated the mechanical interactions of implant-teeth splinting systems under different periodontal supports and number of splinted teeth with rigid and non-rigid connectors using non-linear finite element (FE) approach. Methods Two FE models with normal and compromised periodontal supports containing a Frialit-2 implant splinted to the first and second premolars were constructed. Non-linear contact elements were used to simulate a realistic interface fixation within the implant system and the sliding function of the non-rigid connector. ANOVA was used to test for relative importance of the investigated factors and main effects for each level of the three investigated factors (periodontal supports, teeth splinting and connector designs) in terms of the stress values were performed. Results The simulated results indicated that the cross-interaction of the periodontal support and the splinting situation was a major factor affecting the stress value in alveolar bone. An additional splinting decreased the stress values of bone significantly for a compromised periodontal support. The individual factor of periodontal support also influenced the stress found in the alveolar bone (28%) and implant (72%), and the stress values increased when the periodontal support was reduced. Using different connectors affected the stresses found in bone (15%), implant (21%) and prosthesis (99%). The stress values of the implant and prosthesis increased, but were decreased in bone when the splinting system used non-rigid connectors. The mobility of natural teeth and the implant system between non-rigid and rigid connections showed only small differences. Conclusions A non-rigid connector should be used with caution since it breaks the stress transfer and increases the unfavorable stress values in the implant system and prosthesis. The tooth/implant-supported system with an additional splinting is more efficient in compromised periodontal supports.

Summary Objectives The structural stability and adhesive strength of a large-cavity premolar with a CEREC restoration is a frequent problem in long-term use. This study sought to determine whether an additional reinforced slot could increase tooth/ceramic retention using finite element (FE) analysis and fracture testing. Methods The cavity was designed in a typical MODL restoration failure shape when the lingual cusp has been lost. Two FE restored-tooth models with different cavity designs were created using image processing, contour stacking, and mesh generation. Interfacial (normal and shear) stresses were then calculated with and without the slot design for restored teeth under lateral and axial forces and different interfacial conditions (bonded and de-bonding). For validation, a fracture experiment was performed with and without reinforced slot designs for large ceramic CEREC restorations. Results The maximum stresses at the buccal wall increased when a lateral occlusal force acted on the restored tooth with a slot design. Conversely, the interfacial stresses decreased when the restored tooth received a uniform axial occlusal force. After de-bonding on the buccal tooth/ceramic interface, the stresses increased by an average factor of three over those obtained with a bonded interface. The fracture forces were consistent with the tendencies predicted in FE analyses. Conclusions An additional reinforced slot for the CEREC restoration of a large cavity could increase retention when a restored tooth receives an axial occlusal load. However, the benefits of a slot seem to be doubtful for a premolar often subjected to a lateral load.

This study evaluates the biomechanical interactions of a mini-implant using a plastic revolving cap (PRC) with translation/rotation features for optional orthodontic traction. An orthodontic mini-implant and the PRC consisting of a hexagon connection onto mini-implant with 60 degree switching unit and an extended arm to provide orthodontic wire tied at different positions. The PRC removal force was measured by pull-out testing. The PRC removal force remained larger than three times the finger pulling force (9.3N) after 5 repeated removal tests. The results for the PRC resistant testing showed that the PRC rotational resistant force (20.31±0.83N) is larger than the maximum traction force (about 4.9N) for orthodontic treatment. The mini-implant used with PRC can provide translation and rotation features to change the angles and directions of orthodontic tractions for most effective anchorage preparation under safety consideration.

This study determines the RBFPD (resin-bonded fixed partial dentures) biomechanical aspects to retainer height using structural-thermal coupled finite element (FE) analysis under normal (37°C) and high (51°C) oral temperatures. Three RBFPD FE models with different retainer heights (100, 75, and 50% of the distance from 2 mm above the CE (cementum-enamel) junction to the occlusal surface) were created using image processing, contour stacking, and mapping mesh procedures. After FE model validation, the maximum first principal and von Mises stresses in the remaining tooth (σ(T)) and prosthesis (σ(P)), were recorded for all models under structural-thermal coupled analyses. The simulation results showed that the σ(T) and σ(p) values decreased with greater retainer height as a result of the increasing prosthesis stiffness and maximizing bonding area between the enamel and retainer at normal oral temperature (37°C). However, no significant stress differences were found according to the retainer height varying dimensions at high (51°C) temperatures. The RBFPD retainer height biomechanical response is dominated by the structural analysis result (at 37°C) and it is recommended that the prosthesis retainer have as great a height as possible to decrease the stress values.

Objectives This study determines the relative contribution of changes (design factors) in cavity dimension, restorative material, adhesive layer modulus and thickness and loading condition on the biomechanical response of a premolar adhesive Class II MOD restoration. Methods A validated finite element (FE) model was used to simulate the mechanical responses. The Taguchi method was employed to identify the significance of each design factor in controlling the stress. Results The results indicated that the loading condition was the major factor affecting the stress values (49% in tooth and 46% in cement). Cavity depth was found as the second contributor affecting the stress values (31 % in tooth and 30% in cement), followed by resin cement modulus (12% in tooth and 13% in cement). Other factors were found to have no significant effect on the tooth and cement stress values. Increased stress values were found with lateral force, deeper cavity and higher luting cement modulus. Significant The combined use of FE analysis and the Taguchi method efficiently identified the relative contributions of several restorative factors and indicated that cavity depth was the most critical factor on the cavity dimensions in attaining a proper occlusal adjustment. Reduced lateral occlusal force and lower modulus luting material application are recommended to obtain a better force-transmission mechanism.

This study used a newly developed proximal contact strength (PCS) device to evaluate the tightness of proximal tooth contact for Class II cavity size restoration with different materials using an auxiliary separation ring system. A measurement device based on the equilibrium of forces acted on the clamp rod converts a pull-out force between interdental spaces on a force sensing resistor to express the PCS. This device was designed using dental floss as the test end and can be moved with constant speed during measurement through a bevel gear that transforms the rotation of motor shaft into linear movement of clamp rod. A manikin model was used with 60 artificial first molars in which an mesial occlusal (MO) preparation was ground. Samples were divided into six groups (each n = 10) for simulating amalgam and resin composite restoration with three different cavity sizes. The different cavities were defined using the ratio of the actual isthmus width to the intercuspal width (W) to 1/3, 2/3 and 1. The PCS value in each sample was measured after restoration. The result showed that the mean PCS value and standard deviation were 2283.1 ± 216.5 gf, 2419.1 ± 375 gf and 1737.6 ± 372.7 g for 1/3 W, 2/3 W and W cavities of the amalgam restoration, respectively. The corresponding PCS values were 1178.0 ± 230.4 gf, 1205.8 ± 249.1 gf and 1247.0 ± 157.5 gf for 1/3 W, 2/3 W and W cavities of the resin composite restoration. PCS values with amalgam restoration were larger than those for resin composite restorations under the same cavity size. Large cavity (W) PCS might be lost with amalgam restoration. No significant difference was found in resin composite restoration PCS among the different cavity sizes.

Objective: The aim of this study was to investigate the biomechanical interactions in tooth–implant-supported fixed partial dentures (FPDs) under several loading conditions with different numbers of splinted teeth and connector types (rigid and non-rigid) by adopting the three-dimensional (3D) non-linear finite element (FE) approach. Material and methods: A 3D FE FPD model was constructed containing one Frialit-2 implant in the mandibular second-molar region splinted to the first and second premolars. Frictional contact elements were used to simulate realistic interface conditions within the implant system and the non-rigid connector function. The main effects for each level of the three investigated factors (loading condition, number of splinted teeth and connector type) in terms of the stress values and dissimilar mobility of the natural teeth and implant were computed for all models. Results: The results indicated that load condition was the main factor affecting the stress developed in the implant, bone and prosthesis when comparing the type of connector and the number of splinted teeth. The stress values were significantly reduced in centric or lateral contact situations once the occlusal forces on the pontic were decreased. However, the prosthesis stress for the non-rigid connections was increased more than 3.4-fold relative to the rigid connections. Moreover, the average tooth-to-implant displacement ratios (RTID) with a non-rigid connection were obviously larger than those for rigid connections under axial loading forces. Adding an extra tooth to support a three-unit tooth–implant FPD only exploited its function when the prosthesis withstood lateral occlusal forces. Conclusions: The load condition is the main factor affecting stress distribution in different components (bone, prosthesis and implant) of tooth–implant-supported FPDs. Minimizing the occlusal loading force on the pontic area through selective grinding procedures could reduce the stress values obviously. A non-rigid connector may more efficiently compensate for the dissimilar mobility between the implant and natural teeth under axial loading forces but with the risk of increasing unfavorable stresses in the prosthesis.

Background/purpose Dental care service quality has received increasing attention in recent years. Patient satisfaction is extensively used to evaluate healthcare service quality. The aim of this study was to propose a conceptual framework for identifying the key drivers and provide guidance for enhancing dental care service quality. Materials and methods The dentistry department of a typical Taiwanese hospital was investigated. In total, 400 adult patients, who subsequently visited the studied hospital for dental treatment, participated in this study. Donabedian's structure-process-outcome model was used to explore the dental care service elements. A Kano-type questionnaire was developed as the survey instrument. Results The response rate was 76% (303/400). Cronbach's α value to each question was >0.7, implying that the questionnaire was highly reliable. When investigating 30 quality elements, based on Kano's perspective, 12 elements were classified into must-be attributes, which are regarded as key drivers of patient satisfaction; 10 elements were in the attractive attributes category; and the remaining were one-dimensional attributes. Patient responses to most dental service elements ranged from satisfied to very satisfied. Conclusion Physical characteristics of structural aspects and administration of process aspects are regarded as essential dimensions. Patient satisfaction with the surveyed service elements was positive. Satisfaction with administration-related factors, other than accurate patient records, in the process aspect was at the lowest level, thus there should be opportunities for improvement.