The Effect of Partial Removable Denture Use on Oral Health Related Quality of Life and Masticatory Function, after 5 Years Use

The aim of this study was to evaluate whether partial removable denture use indeed leads to improved oral health related quality of life and masticatory function. Materials and Methods: Partially edentulous patients presenting for removable denture treatment at the Prosthodontics Service in the Hospital Affiliated to Kinshasa University (Democratic Republic of Congo) were assessed for enrolment in this study. After applying exclusion criteria, 378 patients were included in the study, and randomly assigned into 2 groups. Oral health related quality of life (OHIP-23) and mastication time (MaT), number of chewing cycles (MaC), mastication frequency (MaF), and the sizes of the peanut fragments (FraS) were compared in both groups. Statistical significance was set at p < 0.05. Results: The average MaC, MaT, MaF, and FraS were 119 (± SD 53.70), 86.75 (±SD 35.35), 1.38 (±SD 0.25), and 3.3 (±SD 3.25) for the denture group and 77.9 (±SD 23.9), 60.2 (±SD 17.91), 1.29 (±SD 0.15), and 1.5 (±SD 0.7) for the non-denture group, respectively. Conclusion: The overall oral health related quality of life was best in the non-denture than denture.

Risks Factors of Caries and Periodontal Diseases in the Patients, after 5 Years Use a Partial Removable Denture

Objective: The goal of the removable partial denture is to restore impaired esthetics and masticatory function by replacing missing teeth. The aim of this study was to establish a possible correla-tion between removable partial denture in acrylic resin use after 5 years and dental diseases. Materials and Methods: Partially edentulous patients presenting for removable denture treatment at the Prosthodontics service of the Affiliated Hospital of Kinshasa University, Democratic Republic of Congo were assessed in this study. Patients were randomly assigned into 2 groups: Denture and non-denture group. Caries and periodontal diseases were compared between both groups. Statistical significance was set at p < 0.05. Results: The average age in the denture and non-denture-group was 53.15 (±SD 22.05) and 31.59 (±SD 11.98) years. Out of 160 teeth were decayed, both 110 teeth (68.75%) in the denture-group and 50 teeth (31.25%) in the non-denture group. The DMFT index calculated at start time of the study was 0.2 for both groups, after five years was 7.1 for the denture-group and 2.6 for the non-denture-group. The plaque index in the denture-group had an index of 1 and that of non-denture-group was 0.5. Conclusion: The relationship has been found between patients’ wearers a RPD and dental diseases.

Clinical performance of removable partial dentures: A retrospective clinical study

Removable partial dentures (RPDs) (conventional and implant-supported) treatment is considered a viable option to replace missing teeth as inexpensively as possible, but it has limitations. Objectives: This study reports the effect of gender and location (maxilla vs. mandible) on the clinical performance of removable partial dentures (RPDs). Materials and Methods: A total of 100 Patients who had RPDs delivered between 1990-1995 were evaluated. A 4-point scoring system was used to assess seventeen criteria. These criteria include acceptance, stability, support, retention, adaptation, occlusion, integrity, and design of the pros-theses, rest and rest seat preparation, occlusal wear, esthetics, phonetics, tissue condition, mobility of abutments, gingival and plaque indices. The data were analyzed using Kruskal-Wallis and Mann-Whitney U non-parametric statistical tests. Results: The results showed that acceptance of RPDs was rated the lowest. Other reasons for failure were poor retention, lack of integrity of the prostheses and inadequate adaptation. Retention and design of major connectors attributed to Mandibular RPD failure. Success rate of 75% was observed in male compared with 67.2% for female. Maxillary RPDs showed a higher success rate (78%) compared with the mandibular (70.1%). No significant statistical difference in Alpha scores between female and male patients and between maxillary and mandibular RPDs (p < 0.05). Conclusions: The clinical performance of RPDs showed a higher success rate in male patients compared to female patients and the maxillary RPDs showed a higher success rate compared to mandibular.

The Effect of Non-Contact Conditions in a Splinted Fixed Partial Denture on the Load Sharing Mechanism： A Finite Element Study

A computer-aided design model for a fixed partial denture was constructed and used in a finite element analysis to study the overall load sharing mechanism between the fixed partial denture and oral structures while the denture base rested on the al- veolar ridge. To investigate the consequences of non-contact conditions, three additional models were generated incorporating a uniform clearance of 0.125 mm, 0.25 mm, and 0.5 mm, respectively. A 100 N static load located at the free end of the prosthesis was applied while the distal portion of the jaw was set fixed. The results show that whilst releasing the ridge almost entirely, the presence of the clearance drastically increased the load on the splinting teeth. A pull-out force on the canine tooth of about 44 N was computed, accompanied by a mesio-distal moment of about 500 N.cm. The combination of which was similar to the tooth extraction maneuver performed by the dentist. In contrast, the second premolar was found to bear a push-in force of almost 115 N. The first molar, though barely solicited in the contact condition, became substantially loaded in non-contact conditions, which validates the choice of sacrificing three teeth to support the denture.

Effect of Accessory Retention Forms on the Bond Strength of Resin-bonded Fixed Partial Dentures:a 3D Finite Element Study

Interface debonding between prostheses and abutments was the most frequent failure mode of resin-bonded fixed partials dentures(RBFPDs) in clinic. The purpose of this study was to investigate the effect of accessory retention forms on the bond strength of RBFPDs. Three types of 3D finite element models were constructed.The model of posterior metal plate RBFPD with spoon-shaped occlusal rest seats served as the control. The remaining two types of models based on the control added the retention form design of the pin hole and axial groove respectively. The axial or buccolingual load of 150 N was applied on the prosthesis, first premolar and first molar respectively. The maximum principal stresses of the adhesive layer in different models were calculated. Under the load of the same magnitude, the stress due to the buccolingual load was significantly higher than that due to the axial load in the adhesive layer. The proximal shoulder, occlusal rest seats wall and the proximal margin adjacent to the shoulder were the high risk region where the adhesive layer damaged easily. Compared with the control model, the pin and groove models could slightly decrease the stress in the adhesive layer after the axial loading, while the stress in the adhesive layer drastically decreased after horizontal loading and reduced by 22% and 31% respectively. These results indicate that the horizontal occlusal force has a more serious harm to the debonding of RBFPDs. In addition, the accessory retention forms(e.g. pin and axial groove retention forms) can decrease the stress level in the adhesive layer, which are conducive to increase the load-bearing capacity of RBFPDs.

The extraction of survey lines on partial edentulous models

Survey lines are important features on the dental meshes for removable partial denture frameworks design, but few researche has been done by surveying digital models. This article describes a method for identifying survey line on dental meshes and displays survey line in real time. At the beginning, we segment tooth based on morphologic operators to get the tooth parts. The second step is to calculate the viewing direction perpendicular to the occlusal plane. Finally, we extract boundary points on 2D plane, thereby obtaining a survey line in the surveying direction. We have developed a module to demonstrate survey line in real time.

Effect of proximal contact strength on the three-dimensional displacements of implant-supported cantilever fixed partial dentures under axial loading

Objective:This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture(CFPD) under vertically concentrated loading with digital laser speckle(DLS) technique.Methods:Fresh mandible of beagle dog was used to establish the implant-supported CFPD for specimen.DLS technique was employed for measuring the three-dimensional displacement of the prosthesis under vertically concentrated loading ranging from 200 to 3 000 g.The effect of the contact tightness on the displacement of CFPD was investigated by means of changing the contact tightness.Results:When an axial concentrated loading was exerted on the pontic of the implant-supported CFPD,the displacement of the CFPD was the greatest.The displacement of the prosthesis decreased with the increase of contact strength.When the contact strength was 0,0.95,and 3.25 N,the displacement of the buccolingual direction was smaller than that of the mesiodistal direction but greater than that of the occlusogingival direction.When the force on the contact area was 6.50 N,the mesiodistal displacement of the prosthesis was the biggest while the buccolingual displacement was the smallest.Conclusions:The implant supported CFPD is an effective therapy for fully or partially edentulous patients.The restoration of the contact area and the selection of the appropriate contact strength can reduce the displacement of the CFPD,and get a better stress distribution.The most appropriate force value is 3.25 N in this study.

Radio-Frequency Characteristics of Partial Dielectric Removal HR-SOI and TR-SOI Substrates

High-resistivity silicon-on-insulator （HR-SOI） and trap-rich high-resistivity silicon-on-insulator （TR-S01） sub- strates have been widely adopted for high-performance rf integrated circuits. Radio-frequency loss and non- linearity characteristics are measured from coplanar waveguide （CPW） t lines fabricated on HR-SOI and TR-SOI substrates. The patterned insulator structure is introduced to reduce loss and non-linearity char- acteristics. A metal-oxide-semiconductor （MOS） CPW circuit model is established to expound the mechanism of reducing the parasitic surface conductance （PSC） effect by combining the semiconductor characteristic anal- ysis （pseudo-MOS and C-V test）. The rf performance of the CPW transmission lines under dc bias supply is also compared. The TR-SOI substrate with the patterned oxide structure sample has the minimum rf loss （〈0.2 dB/mm up to 10 GHz）, the best non-linearity performance, and reductions of 4 dB and 10 dB are compared with the state-of-the-art TR-SOI sample＇s, HD2 and HD3, respectively. It shows the potential application for integrating the two schemes to further suppress the PSC effect.

Mandibular Anterior Immediate Denture Using Visible Light Cure Acrylic

Management of a 51-year-old female of Afro Trinidadian descent required removal mandibular incisors. This patient’s periodontal condition and her inability to afford pre-prosthetic surgery, bone grafting or even a fixed partial denture for replacement of the proposed units after extraction necessitated alternative treatment options to implants. Her profession required interaction with the public and as such an immediate replacement was essential. Impressions were taken and an immediate partial denture fabricated using a visible light cure acrylic. The mobile teeth were extracted and the denture delivered to the patient with minimal adjustments. The patient was monitored for three months while healing of the extraction site occurred and her periodontal condition was treated. Inability to afford definitive treatment for one year required the denture be maintained for that period. Follow up showed that the aesthetics, function and structural integrity of the denture had not been compromised.

Control factors of partial nitritation for landfill leachate treatment

Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.

Investigations into the coiled tubing partial underbalanced drilling (CT-PUBD)technique for drilling hard formations

To improve the rate of penetration(ROP) in drilling deep and hard formations, this paper proposes a new drilling method called coiled tubing partial underbalanced drilling(CT-PUBD). As a preliminary investigation into the new drilling method, this paper presents predictions of hole cleaning efficiency, drilling speed, cuttings migration and pressure loss in the drilling process with CT-PUBD. Based on numerical simulation and full-scale experimental studies, we conclude that using CT-PUBD, an underbalanced drilling condition can be achieved near the bit while maintaining wellbore safety at the same time. This condition can be achieved using a cuttings discharge device, a rotary packer and a backflow controller.According to the numerical simulations performed in this study, CT-PUBD can achieve high efficiency of hole cleaning.Along the cuttings migration process, the fluid velocities can reach the maximum values in the backflow holes. A full-scale laboratory experimental system was used to test the hydraulic characteristics and obtain the drilling performance of the new technology. The result shows that CT-PUBD significantly improves the ROP compared to the conventional drilling method.

Automatic Generation of Very Efficient Programs by Generalized Partial Computation

Generalized Partial Computation (GPC) is a program transformation method utilizing partial information about input data, properties of auxiliary functions and the logical structure of a source program. GPC uses both an inference engine such as a theorem prover and a classical partial evaluator to optimize programs. Therefore, GPC is more powerful than classical partial evaluators but harder to implement and control. We have implemented an experimental GPC system called WSDFU (Waseda Simplify Distribute Fold Unfold). This paper discusses the power of the program transformation system, its theorem prover and future works.

Optimize Operation of Partial Denitrification System for Simultaneous Treatment of Low C/N Municipal and Nitrate Wastewaters

In order to realize the simultaneous treatment of low C/N municipal and nitrate( NO3^--N) wastewaters,a sequencing batch reactor( SBR) was used to optimize the partial denitrification( PD),which the influent substrate and the anoxic reaction time were appropriately controlled. The carbon and nitrogen removal and the characteristic parameters of PD during long-term operation were studied. Experimental results showed that the PD showed stable characteristics of nitrogen and carbon removal and NO2^--N accumulation after an adaptation of 20 d with municipal wastewater used. The anoxic reaction time was extended from 50 to 70 min with the initial COD/NO3^--N decreased from 3. 0 to about 2. 5. When the influent NO3^--N was 117. 93 mg/L,the effluent NO2^--N and NAR were 23. 10 mg/L and 82. 26%,respectively,and the nitrogen and carbon removal rate reached 91. 76% and 65. 70%,respectively. The effluent NO2^--N/NH4^+ -N meantime reached 1.17-1. 22. Moreover,the cumulative concentration of NO2^--N and the system NAR increased linearly with the consumption of NO3^--N and COD,and the change trend was highly significant within 0-20 min,and gradually flattened.

Effect of initial ammonium concentration on a one-stage partial nitrification/anammox biofilm system:Nitrogen removal performance and the microbial community

One-stage partial nitrification coupled with anammox(PN/A)technology effectively reduces the energy consumption of a biological nitrogen removal system.Inhibiting nitrite-oxidizing bacteria(NOB)is essential for this technology to maintain efficient nitrogen removal performance.Initial ammonium concentration(IAC)affects the degree of inhibited NOB.In this study,the effect of the IAC on a PN/A biofilm was investigated in a moving bed biofilm reactor.The results showed that nitrogen removal efficiency decreased from 82.49%±1.90%to 64.57%±3.96%after the IAC was reduced from 60 to 20 mg N/L,while the nitrate production ratio increased from 13.87%±0.90%to 26.50%±3.76%.NOB activity increased to1,133.86 mg N/m^(2)/day after the IAC decreased,approximately 4-fold,indicating that the IAC plays an important inhibitory role in NOB.The rate-limiting step in the mature biofilm of the PN/A system is the nitritation process and is not shifted by the IAC.The analysis of the microbial community structure in the biofilm indicates that the IAC was the dominant factor in changes in community structure.Ca.Brocadia and Ca.Jettenia were the main anammox bacteria,and Nitrosomonas and Nitrospira were the main AOB and NOB,respectively.IAC did not affect the difference in growth between Ca.Brocadia and Ca.Jettenia.Thus,modulating the IAC promoted the PN/A process with efficient nitrogen removal performance at medium to low ammonium concentrations.

The effect of dissolved oxygen concentration on long-term stability of partial nitrification process

Dissolved oxygen(DO)concentration is regarded as one of the crucial factors to influence partial nitrification process.However,achieving and keeping stable partial nitrification under different DO concentrations were widely reported.The mechanism of DO concentration influencing partial nitrification is still unclear.Therefore,in this study two same sequencing batch reactors(SBRs)cultivated same seeding sludge were built up with realtime control strategy.Different DO concentrations were controlled in SBRs to explore the effect of DO concentration on the long-term stability of partial nitrification process at room temperature.It was discovered that ammonium oxidation rate(AOR)was inhibited when DO concentration decreased from 2.5 to 0.5 mg/L.The abundance of Nitrospira increased from 1011.5 to 1013.7 copies/g DNA,and its relative percentage increased from 0.056%to 3.2%during 190 operational cycles,causing partial nitrification gradually turning into complete nitrification process.However,when DO was 2.5 mg/L the abundance of Nitrospira was stable and AOB was always kept at 1010.7 copies/g DNA.High AOR was maintained,and stable partial nitrification process was kept.Ammonia oxidizing bacteria(AOB)activity was significantly higher than nitrite oxidizing bacteria(NOB)activity at DO of 2.5 mg/L,which was crucial to maintain excellent nitrite accumulation performance.

Sludge fermentation liquid addition attained advanced nitrogen removal in low C/N ratio municipal wastewater through short-cut nitrification-denitrification and partial anammox

Biological nitrogen removal of wastewater with low COD/N ratio could be enhanced by the addition of wasted sludge fermentation liquid(SFL),but the performance is usually limited by the introducing ammonium.In this study,the process of using SFL was successfully improved by involving anammox process.Real municipal wastewater with a low C/N ratio of 2.8–3.4 was treated in a sequencing batch reactor(SBR).The SBR was operated under anaerobic-aerobic-anoxic(AOA)mode and excess SFL was added into the anoxic phase.Stable short-cut nitrification was achieved after 46d and then anammox sludge was inoculated.In the stable period,effluent total inorganic nitrogen(TIN)was less than 4.3 mg/L with removal efficiency of 92.3%.Further analysis suggests that anammox bacteria,mainly affiliated with Candidatus_Kuenenia,successfully reduced the external ammonia from the SFL and contributed approximately 28%–43%to TIN removal.Overall,this study suggests anammox could be combined with SFL addition,resulting in a stable enhanced nitrogen biological removal.

Methanation and chemolitrophic nitrogen removal by an anaerobic membrane bioreactor coupled partial nitrification and Anammox

An AnMBR-PN/A system was developed for mainstream sewage treatment.To verify the efficient methanation and subsequent chemolitrophic nitrogen removal,a long-term experiment and analysis of microbial activity were carried out.AnMBR performance was less affected by the change of hydraulic retention time(HRT),which could provide a stable influent for subsequent PN/A units.The COD removal efficiency of AnMBR was>93%during the experiment,85.5%of COD could be recovered in form of CH4.With the HRT of PN/A being shortened from 10 to 6 h,nitrogen removal efficiency(NRE)of PN/A increased from 60.5%to 80.4%,but decreased to 68.8%when the HRTPN/A further decreased to 4 h.Microbial analysis revealed that the highest specific ammonia oxidation activity(SAOA)and the ratio of SAOA to specific nitrate oxidation activity(SNOA)provide stable NO_(2)^(−)-N/NH_(4)^(+)-N for anammox,and anammox bacteria(mainly identified as Candidatus Brocadia)enriched at the bottom of Anammox-UASB might play an important role in nitrogen removal.In addition,the decrease of COD in Anammox-UASB indicated partial denitrification occurred,which jointly promoted nitrogen removal with anammox.

Effect of partial pit exhaust ventilation system on ammonia removal ratio and mass transfer coefficients from different emission sources in pig houses

A partial pit exhaust ventilation(PPEV)system installed below the slatted floor has been widely used in fattening pig barns nowadays in Denmark.Experimental tests showed that annually around 50%of ammonia emissions was collected by PPEV system.However,the percent of emissions collected by PPEV system from different emission sources including slurry manure surfaces,top surfaces,bottom surfaces and side surfaces of the slatted floor has not been investigated as well as the mass transfer coefficients.This study applied CFD modeling to investigate the removal ratio of ammonia emissions from four emission surfaces including the top,side,bottom surfaces of the slatted floor and slurry manure surfaces.The CFD model was validated by experimental air speeds measured in a room equipped with two full-scale pigpens.The validated CFD model was further adopted to simulate cases under five ventilation rates(2000-4000 m^(3)/h),four emission sources and two locations of PPEV system exhaust.The results showed that the removal ratios of ammonia emissions by PPEV system from the four emission sources were generally higher for the cases that the PPEV exhaust was installed opposite to the air supplier than the values of those cases that the PPEV exhaust was located at the same side of side wall air supplier.The removal ratios of ammonia emissions were the highest with the emission source of slurry manure surface and generally 30%higher than the values of other cases.The mass transfer coefficients with the emission sources on the side surfaces of the slatted floor were the largest.The results indicated that the airflow patterns and locations of emission sources greatly influenced the removal ratios of ammonia emissions and ammonia mass transfer coefficients.

肯氏Ⅰ、Ⅱ类牙列缺损数字化印模及模型在可摘局部义齿中的应用

目的评估肯氏Ⅰ、Ⅱ类牙列缺损数字化印模及树脂模型技术在可摘局部义齿(RPD)中的应用效果。方法选择肯氏Ⅰ、Ⅱ类牙列缺损患者,按照义齿制作流程分组:数字化印模/树脂模型/钴铬合金铸造支架组(A组)、数字化印模/树脂模型/激光打印钛支架组(B组)、藻酸盐印模/石膏模型/钴铬合金铸造支架组(C组)、藻酸盐印模/石膏模型/激光打印钛支架组(D组),每组40例。对最终完成的RPD在口内就位情况进行检查,评估指标包括卡环固位力、连接体和基托在口内的密合度、咬合准确度,各项指标评估分值使用Kruskal-Wallis秩和检验进行分析。结果4组RPD各项指标的评分值差异无统计学意义。结论利用数字化印模及树脂模型完成的铸造钴铬合金和激光打印钛支架式RPD能够满足肯氏Ⅰ、Ⅱ类牙列缺损患者的临床修复要求。

无牙颌患者种植固定义齿饰面材料研究及应用进展

目前无牙颌患者种植固定义齿常用饰面材料包括丙烯酸树脂、聚合瓷、陶瓷、氧化锆等,不同材料的理化性质、临床表现各不相同。临床上固定义齿饰面材料的选择与患者口腔修复空间及软硬组织状况、力、生活习惯、口腔副功能、对颌牙材料及患者期望有关。无牙颌患者种植固定义齿相关的常见机械并发症为饰面材料的折裂/崩瓷及磨损,可通过咬合调整、修复体设计加工以及合适的修复材料选择予以规避。本文就常用无牙颌患者种植固定义齿饰面材料的特点、选择与设计要点、临床常见修复体材料相关并发症的病因及处理展开综述,以期为临床无牙颌患者种植固定义齿饰面材料的选择提供参考。