An Alternative Method for Incorporating Fiber Meshes in Complete Upper Dentures

The most commonly used material for constructing complete dentures is polymethyl methacrylate (PMMA). However, the strength characteristics of PMMA, such as impact strength and fatigue strength, are poor, and fracturing of PMMA dentures is a common problem in prosthodontic practice. Reinforcing PMMA with various materials, such as carbon fibers, glass fibers (fiberglass), and ultrahigh modulus polyethylene fibers, has been suggested to strengthen the denture-base material. A common problem encountered when packing the resin on these specimens is fiber slippage beyond the denture edges. The present study proposes an alternative method of incorporating fiber meshes into complete dentures, whereby a thin filament of self-polymerizing resin at the perimeter of the fiber mesh is produced, giving a clear and stable shape to the mesh that fits the upper jaw cast. During placement of the shaped mesh on the cast, a positive-negative relationship is created between the mesh and cast, which immobilizes the mesh during the incorporation process.

The lingualized occlusion of complete denture

This article reviews the literatures dealing with the lingualized occlusion of complete denture including the origin,development and research.Lingualized occlusion is a valuable concept because many advantages of anatomic and nonanatomic occlusions are retained,satisfactory occlusion is easily obtained,balanced occlusion can be accomplished.

Investigation of the torsional deformation of the complete upper denture: A pilot study

The aim of this research is to clarify whether the midline axis of the complete upper denture (CUD) is the axis of its torsion during loading, apart from the known bending deflection. Furthermore the present study is intended to estimate the influence of the anterior notches on the torsional deformation of the CUD. Using commercial edentulous molds and standardized procedures, six identical CUDs were fabricated with an initial fraenal notch of 5 mm. Two additional notch conditions were produced by deepening the notch to a total depth of 9 mm and by creating an incisal diastema of 7 mm. Five biaxial (also known as “fish bone”) strain gauges were cemented onto the palatal section of the dentures so that their middle axis coincided with the midline axis of the outer surface of the denture. For the denture specimen used in this study, the specific point of torsion was detected 2 cm from the point of contact of the two artificial central incisors. The presence of a deep fraenal notch and the combination of the deep fraenal notch with the presence of an incisal diastema increased the torsion of the CUD to a significant level (P = 0.006 and P = 0.05, respectively). It was shown that the midline can be the CUD’s axis of torsion. Biaxial strain gauges could be a reliable method of measuring the torsional deformation of the CUD.

Preparation and Lab Evaluation of a New Denture Adhesive

To develop a new kind of denture adhesive （DA）, then to evaluate its mechanical and chemical properties, polyethylene oxide, methyl cellulose, sodium alginate, and cellulose ether, were viewed as four main factors, which would affect bonding load of DA, while two levels of each component were differentiated. Following table L12（211）, twelve different formulae were designed by orthogonal design and bonding load values were recorded. According to bonding load of each formula, the optimized formula was selected out as this new adhesive material, Comfort-DA II. The changing of bonding load values of Comfort-DA II marinating in artificial saliva were measured, and an existing product, Protefix and Comfort-DA, were used as controls. Following initial load readings, samples and controls were measured from 1- to 12- hour intervals, respectively. Comfort-DA II was diluted at 1.0%, 2.0%, 3.3%, 5.0%, and 10.0% concentrations, and pH values were measured at 1-, 2-, 3-, 4-, 5-, 6-, and 8-hour intervals. Comfort-DA II presented as a pale-yellow paste. Group 6 gained the highest bonding load value of [193.8 （4.2）] N. The mean bonding load of Comfort-DA II was statistically different to Comfort-DA （p = 0.004） and Protefix （p = 0.006）. Comfort-DA II exhibited a progressive increase in pH value over time and was slightly alkaline. Comfort-DA II showed significantly elevated mechanical and chemical properties, comparing to Comfort-DA. The results also indicate that orthogonal design may be an efficacious way to develop new dental materials.

Swallowing threshold parameters of subjects with complete dentures and overdentures

Aim: To compare the chewing process and swallowing threshold parameters of subjects with complete dentures and overdentures with data obtained from subjects with complete natural dentitions. Metho-dology: The chewing process in terms of swallowing threshold parameters of four groups of subjects with complete dentures (all females) was quantified by sieving particles after chewing of an artificial test ‘food’ and compared with that of subjects with com-plete natural dentitions as a reference group (33 sub-jects). All subjects (except those of the reference group) had a complete denture in the upper jaw. Regarding the lower jaw two groups with complete dentures (with high (24 subjects), respectively low mandible (12 subjects)) and two groups with overdentures (implant-retained (22 subjects), respectively natural root supported (19 subjects)) were composed. Results: The ‘overdenture-implants’ group needed significantly more chewing cycles and time (mean: 45 cycles in 32 seconds) until ‘swallowing’ compared to the group with complete natural dentitions (mean: 26 cycles in 19 seconds until ‘swallowing’). Also the ‘complete denture-low mandible’ group needed sig-nificantly more cycles and time (mean: 52 cycles in 44 seconds) until ‘swallowing’ than the complete dentition group. In the ‘overdenture-natural roots’ group these outcomes (33 cycles in 24 seconds) were not significantly different compared with the complete dentition group. The ‘complete denture-high mandi-ble’ group (32 cycles in 26 seconds) needed not sig-nificantly more cycles until ‘swallowing’, however time until ‘swallowing’ was significantly longer com-pared to the complete dentition group. All denture groups had significantly larger mean particle sizes when ‘swallowing’ (sizes in the order of 3 mm) than the natural dentition group (about 2 mm). Conclusion: Despite efforts to compensate for a reduced chewing efficiency, subjects with complete dentures (including overdentures) had 50% larger median particle sizes when ‘swallowing’ compared to subjects with complete natural dentitions.

Class III Reversion with Immediate Complete Denture and Immediate Implant-Retained Overdenture: Case Report

With the increased life expectancy, complete dentures have been used in the treatment of edentulism progressively. It restores stomatognathic system functions, providing improvements in chewing, aesthetics, and phonetics. The aim was to report an oral rehabilitation of a patient with severe aesthetic and functional impairment, with Angle’s class III malocclusion. The patient sought the extension project of the School of Dentistry of the Federal University of Minas Gerais with aesthetic complaints. After clinical and radiographic evaluation, the proposed planning was immediate complete denture maxilla and immediate implant-retained overdenture in mandible. During clinical evaluation it was observed that the patient was Angle’s III. The rehabilitation was performed as proposed and at the end of the treatment, it was possible to revert the class III occlusal pattern to Angle’s I. The excellent maxillomandibular relationship was achieved, which ensured optimal facial aesthetics and functional condition. It was concluded that the immediate complete dentures and immediate implant-retained overdenture might be beneficial for restoring the aesthetics and function of patients with Angle’s class III malocclusion.

Estimation of Fatigue Strength of Reinforced Complete Upper Denture Using a Newly Designed Testing Machine: A Laboratory Research Project

In the present study, an aero pneumatic fatigue testing machine for complete dentures was designed, fabricated, and tested for the evaluation of the fatigue life of reinforced complete upper denture (CUD). On completion and testing, it was observed that the machine has the potential of generating reliable number of cyclic data. The machine’s performance was evaluated using test specimens of identical CUDs that were machined in conformity with standard procedures. The fatigue machine compressed the lower dental arch over the upper denture-specimen in centric occlusion, in the same way that the two masticatory muscles pull the lower jaw over the upper jaw during chewing. The incorporation of glass fibres into the CUD using a sandwich technique quadruples the lifespan of the denture (P = 0.004). The low standard deviation, along with the low coefficient of variation (CV) of the group of unreinforced dentures shows the repeatability of the results and the reliability of the machine. The high standard deviation and coefficient of variation of reinforced dentures was expected, since a high variation of results is usually recorded in fibre reinforcement cases. This research confirmed the view that the crack during denture fracture initiates in the anterior palatal area and propagates to the posterior.

Effect of Phyllanthus emblica Linn.on Candida adhesion to oral epithelium and denture acrylic

Objective:To investigate the effect of Phyllanthus emblica(P.emblica) Linn,ethanolic extract on the adhesion of Candida albicans(C.albicans) to human buccal epithelial cells(BECs) and denture acrylic surfaces.Methods:Human BECs and transparent acrylic strips were pretreated with ethanolic extract solution of P.emblica fruits at concentration ranged from 18.7 to 300 mg/mL.After washing BECs and the strips were inoculated with three strains of C.albicans (ATCC 10281 and two clinical isolates)(10~7 cells/mL).Normal saline solution(NSS) and 0.2% chlorhexidine gluconate were used as negative and positive controls,respectively.BECs were harvested on 12μm-polycarbonate filters(Millipore,USA).The membrane filters and the strips were stained with Gram stain.Adherent yeast cells on 100 randomly selected epithelial cells and 20 randomly selected fields on each strip were counted under microscope.The statistical significance was calculated by Kruskal-Wallis and Tukey tests at a significant level of P【0.05. Results:Significant lower numbers of all strains of yeasts adhering to BECs and acrylic strips were observed after exposure to 75-300 mg/mL of plant extract compared with NSS.Conclusions: The present study demonstrates that P.emblica ethanolic extract interferes with the adhesion of C. albicans to BECs and denture acrylic surfaces in vitro.

Two Cases of Severe Dementia Showing Dramatic Improvement after Denture Placement

Severe dementia, including Alzheimer’s disease, is intractable and progressive. The purpose of this study was to document the improvement observed in two cases of severe dementia after denture placement. The subjects, two women in their 70s with severe dementia, were diagnosed with Alzheimer’s disease by the medical doctors in charge of their cases. In the first case, the subject’s symptoms included severe disorientation, impaired communication, and a tendency to wander. Two weeks after a lower complete denture placement, she was able to greet others. Five weeks later, she was able to communicate and precisely read an analog clock. Her condition continued to improve for at least 3 months. In the second case, the subject’s mouth was always open. She was bedridden in a vegetative state and hardly moved, talked, or laughed;it was impossible to communicate with her. Only a few seconds after an upper complete denture placement, she started to talk, albeit unintelligibly. Two weeks after a lower complete denture placement, she could communicate normally, laugh, and walk without help. Although the underlying mechanism has not yet been clarified, the author hypothesizes that positive signals from the oral area are transferred to the brain as positive stimulation via the trigeminal nerve, the largest cranial nerve.

Inhibition of candida adhesion to denture acrylic by Boesenbergia pandurata

Objective:To investigate effect of Boesenbergia pandurata(B.pandurata) rhizome extract on adhesion of Candida albicans(C.albicans) to acrylic surface.Methods:Transparent acrylic strips were prepared and divided into three groups with pretreatment by extract solution of B. pandurata rhizome at concentration of 25,50 and 100 mg/mL,respectively.After washing, the strips were then inoculated with two strains of C.albicans(ATCC13803 and the clinical isolate)(10~7 cells/mL).Normal saline solution and 0.2%chlorhexidine gluconate were used as negative and positive controls,respectively.Stained the strips with modified Cram stain without counterstain.Adherent yeast cells were direct counted under microscope(OlympusCX31, Japan) in 20 randomly selected fields on each strip.The statistical significance was calculated by Kruskal-Wallis and Mann-Whitney non-parametric tests at a significance level of P 【 0.05.Results:Pretreatment with B.pandurata extract significantly reduced the adhesion of both strains of C.albicans to acrylic surfaces in a dose dependent manner.Conclusions: This observation indicates that B.pandurata extract has an inhibitory effect on the ability of C. albicans to adhere to denture acrylic and could be employed as an antifungal agent for preventing denture stomatitis.

Using a Simple Chair-Side Copy Denture Technique in the AvaDent Digital Denture Process: A Case Report and Review

Introduction: Several techniques have been described by which a pair of dentures may be replicated. Case Report: The method described in this paper used materials readily available in a private practice to generate a pair of duplicate dentures for a 74-year-old Black male, which captured all of the features of the patients’ existing pair. These were modified chair-side and used to capture vital information on fit, occlusion and aesthetics, forming a template which was transferred to the laboratory and used to generate new dentures via the traditional laboratory process. The same template was also used to generate a pair of “AvaDent Digital Dentures” by digital scanning and production of a digital denture template for try and then fabrication of the digital denture. Conclusion: The results of this pilot study show that this simple chair-side method of fabricating duplicate dentures can be incorporated successfully into the AvaDent Digital Denture fabrication process to generate a pair of dentures with comparability if not superior fit and aesthetics to a pair fabricated from the same template via the traditional laboratory process.

Biomechanical Analysis of Implant Assisted-Overdentures with Variations in the Attachments Systems

The aim of this study was to assess the stress patterns on the peri-implant zone and residual alveolar ridge in different overdenture attachment system designs by the photoelasticity method. Four attachments systems were tested: O-ring, ERA, Bar-clip, and Bar-clip/O-ring association. The prostheses were loaded with 100 N in five pre-determined points and the photoelastic model was evaluated by a circular polariscope. The anterior load, O-ring, and ERA showed better stress distribution in relation to the bars systems, which presented stress levels surrounding implants. The molar load, Bar-clip/O-ring association, presented the biggest stress concentration on the peri-implant region in relation to the others. When the second molar was loaded, there was a concentration of stress in the alveolar ridge in all situations analyzed. Within the limitation of this “in vitro” study, it could be concluded that there were biomechanical differences among the attachments systems analyzed, principally between isolated and the bars systems. The O-ring showed better stress distribution and the Bar-clip/O-ring showed higher stress concentration.

One-piece implant-supported overdenture in fully edentulous patients: Report of two cases

Dental implants with a reduced diameter can be placed in regions that lack adequate bone volume enabling functional and aesthetic oral rehabilitation without the complicated bone augmentation procedures.This article describes surgical and prosthetic procedures used in oral rehabilitation using Straumann R one-piece Mini Implants(2.4-mm diameter with Optiloc R prosthetic connection system)in two fully edentulous women aged 57 and 74.Both patients presented with severe ridge resorption.Ten one-piece mini dental implants(six on maxillary arch and four on mandibular arch)were placed in each patient to support new complete overdentures.Both patients were delighted with the results and regained their social lives.In addition,stabilized dentures allowed the patients to regain fundamental functions of the mouth:chewing and verbal(speech)and non-verbal(smiling)communication without the fear or difficulty experienced while wearing dentures that can move.In conclusion,mini implants offer an efficient,economical,and less invasive solution,especially for edentulous patients with atrophic bone structure or who cannot undergo complex surgical procedures.

正中关系的临床决策

正中关系(CR)最初应用于无牙颌的全口义齿修复,后来逐渐应用于有牙颌的临床诊疗。关于CR在有牙颌中的应用,一方面对其合理性有不少质疑,如在颞下颌关节紊乱病治疗中,CR是否应作为诊疗核心?咬合重建修复治疗中,CR是否应作为建颌位?正畸治疗中,CR是否应作为目标颌位?但另一方面,CR的各种临床运用却是客观存在的。根据现有认知,本文汇总整理了争议不大的几种主要临床场景的适用条件,初步提出了CR临床应用时的决策树,供临床参考。

分体式颌位关系记录托盘的设计与应用

现有的颌位关系记录托盘为上下一体式设计,在临床使用过程中无法准确获取上颌平面、上唇下约1 mm的位置、上唇支撑度等重要信息。从而使得数字化颌托(或诊断义齿)准确性欠佳,为后继进行准确边缘整塑印模及最终颌位关系记录与转移带来困难。该文介绍了一种分体式颌位关系记录托盘的设计、临床使用方法及要点。其能够准确获取上颌平面、上唇下约1 mm的位置、上唇支撑度等重要信息,为后继进行准确的颌位关系记录与转移提供参考,也为利用口内扫描获取数字化印模后,基于采用分体式颌位关系记录托盘获取的平面、上唇下约1 mm的位置、上唇支撑度等信息直接制作全口义齿奠定基础。

磁性附着体联合卡环固位可摘义齿修复双侧游离端缺失牙列缺损的效果观察

目的观察磁性附着体联合卡环固位可摘义齿修复双侧游离端缺失牙列缺损的临床效果。方法选取2021年4月至2023年4月我院收治的80例双侧游离端缺失牙列缺损患者,分为对照组(40例,接受卡环固位可摘义齿修复)、研究组(40例,接受磁性附着体联合卡环固位可摘义齿修复)。比较两组的义齿松动情况、牙周健康恢复情况及不良反应发生情况。结果研究组义齿Ⅰ度松动发生率高于对照组,义齿Ⅱ度松动发生率低于对照组(P<0.05)。研究组治疗后的菌斑指数、龈沟积液、龈沟出血指数均低于对照组(P<0.05)。研究组不良反应发生率为5.00%,低于对照组的25.00%(P<0.05)。结论磁性附着体联合卡环固位可摘义齿修复双侧游离端缺失牙列缺损的效果显著,可明显改善患者的口腔环境,促进患者牙周健康恢复,且安全性较高。

生物功能修复系统应用于无牙颌患者的疗效分析

目的 评价内蒙古地区应用生物功能修复系统制作全口义齿的临床效果。方法 2019年7月至2023年6月来包头医学院第一附属医院就诊的无牙颌患者72例纳入研究,随机分为对照组(n=36)和实验组(n=36),对照组选用传统全口义齿修复,实验组选用生物功能义齿修复系统制作。两组患者分别进行咀嚼效率评价、口腔健康相关生活质量评估以及义齿压痛特征性分析。结果 (1)咀嚼效率实验组高于对照组,差异具有统计学意义(t=6.774, P <0.01)。(2)实验组义齿在戴用舒适度、吸附效果、黏膜疼痛、溃烂和复诊的频次等方面都明显优于传统方法制作的全口义齿,差异具有统计学意义(P <0.05);义齿在戴用恶心、味觉异常、口齿不清和精神心理因素方面无明显区别,差异无统计学意义(P> 0.05)。(3)对疼痛特性分析显示,实验组黏膜出现中重度压痛的人数(6例)明显少于对照组义齿(16例),且以无痛或轻度居多。结论 生物功能义齿修复系统应用于全口义齿方面临床效果显著,是一种更舒适的义齿修复新方法。

无牙颌患者人格特征对面部美学满意度的影响

目的探讨人格特征在无牙颌患者自我面部美学评价中的作用,为提升患者全口义齿修复后的美学满意度提供借鉴。方法随机选取行全口义齿修复治疗的无牙颌患者22例,在治疗前,艾森克人格问卷(EPQ)N量表被用于评估患者的情绪稳定性。在治疗前和治疗后3个月,面部美学评分问卷和三维摄影测量系统(3dMD)被分别应用于评估患者对面部外观的满意度及颌面软组织的变化。此外,利用N量表评分、面部美学测量指标和面部美学评分,建立多重线性回归模型。结果治疗后,患者面中部与面下部的比例与面型正常人群的差值缩小了(3.85±2.63)%,鼻唇角与正常人群的差值缩小了(6.66±5.39)°。多重线性回归模型结果显示:N量表评分及治疗前后面部比例与正常面型差值的变化值均可影响患者正面美学满意度,而N量表评分及鼻唇角与正常面型差值的变化值均可影响患者侧面美学满意度。纳入模型的两个自变量(N量表评分和颌面软组织变化)对于正面和侧面美学满意度的影响均具有统计学意义(P<0.001)。其中,N量表评分增加时,患者正面和侧面美学满意度均下降(B<0)。结论人格特征可影响无牙颌患者面部美学满意度,故在全口义齿修复治疗中应为不同人格的患者制定合理的诊疗方案,从而达到提高患者面部美学满意度的目标。

可摘局部旧义齿改造全口义齿修复牙列缺失一例

传统全口义齿是口腔修复中一种较为常规的无牙颌修复方式。但其流程繁琐,过程复杂[1]。临床中会遇到患者已行可摘局部义齿修复,佩戴时间不足5年,局部义齿使用情况良好,但就诊时余留牙缺失,需要镶佩全口义齿。为简化操作流程,降低技术敏感性,提高患者对新义齿的适应性及满意度,考虑采用复制义齿技术进行全口义齿修复。本文报告一例下颌牙列缺失病例,通过改造旧可摘局部义齿,利用组织调整剂(tissue conditioner,TC)制取动态印模,最终通过复制义齿为患者制作了一副全新的下颌全口义齿,并取得了满意的临床效果。

三维打印全口义齿树脂基托尺寸稳定性的研究

目的:量化评价数字光处理(digital light processing,DLP)技术打印的上颌全口义齿树脂基托组织面及各功能区在14 d内的形变。方法:基于上颌无牙颌标准石膏模型设计并用DLP技术打印6副上颌全口义齿树脂基托。在基托打印完成第1、7、14天分别对其组织面进行扫描。将扫描所得数据和基托设计文件导入Geomagic 2014软件中进行最佳拟合对齐与三维形态偏差分析。进一步,在软件中将上颌基托组织面细分成主承托区、副承托区、边缘封闭区、缓冲区与上颌后堤区,量化分析各功能区在14 d内的形变。结果:三维形态分析结果显示基托组织面在双侧上颌结节区域与上颌后堤区形变最大且方向相反。对各功能区的分析显示形变从小到大依次是缓冲区、副承托区、主承托区、边缘封闭区和上颌后堤区。结论:三维打印上颌全口义齿基托会随着时间发生一定的形变,各功能分区变形量不同。