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 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.

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.

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。

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。

热处理技术对3D打印钛合金试件机械性能的影响

背景:近年来,增材制造(又称3D打印)逐渐成为制作可摘局部义齿钛合金支架的主流方式。热处理作为改善3D打印钛合金支架机械性能的重要方法而成为目前的关注热点。目的:总结目前应用于3D打印钛合金试件的主要热处理技术(包括退火处理、固溶时效处理、热等静压处理及其他热处理)以及这些热处理技术对3D打印钛合金试件机械性能、微观结构的影响,为改进可摘局部义齿钛合金支架的热处理技术提供理论依据。方法:采用计算机检索中国知网、PubMed和ScienceDirect数据库中有关3D打印钛合金热处理试件的文献资料,检索时限为2012-2023年,根据纳入和排除标准,最终选取61篇文献进行综述分析。结果与结论:①使用常规退火技术处理3D打印钛合金试件,使其在500-900℃下保持2-4 h,能有效增加3D打印钛合金试件的延伸率。②固溶时效处理相较于常规退火技术更复杂,固溶时效处理后的钛合金试件在屈服强度方面表现突出,并且有更好的耐腐蚀性;但固溶时效处理后的3D打印钛合金试件在延伸性方面没有优势。③热等静压处理可以减少3D打印钛合金试件的内部缺陷,可明显增加3D打印钛合金试件延伸率,并增加其疲劳寿命。④快速热处理可以明显提高3D打印钛合金试件的延伸率,并且速度更快,在延伸率提升和热处理效率方面,比以往常规的退火更具优势。⑤循环热处理对3D打印钛合金试件延伸率的提升超过了常规退火,循环热处理可明显改善3D打印钛合金试件的晶粒结构,但热处理时间过长,效率较低。

553例老年患者活动义齿修复方式的探讨与分析

目的探讨并分析553例老年患者活动义齿的修复设计方案。方法选择2021年1月至2022年6月于滨州医学院附属烟台口腔医院就诊的553例多数牙缺失要求活动义齿修复的老年患者,采用弯制卡环式活动义齿,状况欠佳余留牙齿处的基托设计为铸造网状基托,戴用后1个月、6个月、1年期复诊随访。对义齿的咀嚼功能、固位和稳定性、语言发音以及舒适性进行问卷调查,比较患者修复后的满意度。结果采用此设计的老年患者佩戴义齿后,咀嚼功能好,固位、稳定性好,老年患者尤其对摘戴灵活及可能再使用的效果满意。结论铸造支架配合网状基托及弯制卡环义齿是适合老年患者需求的一种修复方式。

垫式可摘局部义齿与普通可摘局部义齿修复治疗牙列缺损合并中重度磨损患者的临床疗效

目的研究牙列缺损合并中重度磨损患者应用垫式可摘局部义齿和普通可摘局部义齿治疗的临床效果。方法选取2022年3月—2023年2月山东省济南市第一人民医院收治的60例牙列缺损合并中重度磨损患者为研究对象,按照不同治疗方式分为对照组(30例)和观察组(30例)。对照组给予普通可摘局部义齿修复治疗,观察组实施垫式可摘局部义齿修复治疗。比较两组临床疗效、咀嚼功能、菌斑指数、牙龈指数、颞下颌功能。结果观察组临床治疗优良率为96.67%(29/30),高于对照组的76.67%(23/30),差异有统计学意义(χ^(2)=5.832,P<0.05)。治疗后,观察组牙龈指数和菌斑指数均低于对照组,咀嚼效率高于对照组,差异有统计学意义(P均<0.05)。观察组颞下颌功能治疗总有效率高于对照组,差异有统计学意义(P<0.05)。结论垫式可摘局部义齿对牙列缺损合并中重度磨损患者的咀嚼功能和颞下颌关节功能有明显的改善作用,可明显减少患者的牙龈指数和菌斑指数,具有较好的临床应用价值。

外胚层发育不全患者牙列缺损修复1例及文献回顾

目的 探讨外胚层发育不全患者先天缺牙的治疗方案,为临床提供参考。方法 报道1例面中份凹陷,颏部前突,面下1/3发育不足的外胚层发育不全患者,患者上颌多颗牙先天缺失,余留牙为畸形牙,下颌牙列先天缺失,牙弓较小,上下牙槽骨发育不良。通过上颌可摘局部义齿、下颌在数字化导板辅助下进行前牙区种植,杆卡式种植覆盖义齿对其进行治疗,并对其治疗方案进行文献回顾。结果 患者佩戴义齿后固位及稳定佳,咬合关系良好,患者面部外形恢复较好,上下唇饱满,面下1/3与面中1/3基本相等,恢复了咀嚼功能。文献回顾结果表明,先天缺牙的外胚层发育不全患者的口内情况通常比较复杂,修复困难,对此类患者常见的修复方式包括固定桥、可摘局部义齿、全口义齿、覆盖义齿和种植义齿,需要根据患者口内实际情况选择不同的治疗方案。目前,对于外胚层发育不全患者先天缺牙的治疗尚未达成共识,有学者建议缺牙少的患者优先选择固定修复,缺牙多的患者选择可摘义齿或种植覆盖义齿修复,未成年患者优先选择活动修复,待颌骨发育完成后视情况更换永久固定修复。结论 对于外胚层发育不全先天缺牙的患者,应该充分考虑各方面因素,以修复为导向个性化制定可行的修复方案。

数字化印模技术在可摘局部义齿中的应用现状

可摘局部义齿具有强度高、价格低、适应证广、创伤小及可修理等特点,是治疗牙列缺损的重要手段之一。随着人口老龄化日趋凸显,可摘局部义齿在未来仍将是一种常用的修复方式。可摘局部义齿的制作离不开精确的印模技术,传统可摘局部义齿印模制取过程中存在诸多不足,如就诊次数多、耗时长、制作过程复杂、污染高、浪费多、效率低、质量不易控制等。然而,数字化印模的出现为可摘局部义齿印模的制取提供了新的技术支持,数字化印模技术具有高精度、舒适性、高效、缩短治疗时间以及个性化设计等优势,有助于提高可摘局部义齿修复的效果和患者的满意度。数字化印模技术作为全程数字化可摘局部义齿修复诊疗的前提和基础,其对口腔模型重建的精度直接影响最终义齿修复效果。目前,数字化印模技术已广泛运用于口腔修复领域,本文将对数字化印模技术在可摘局部义齿中的应用现状进行综述,以期进一步指导临床应用。

不同金刚砂车针对两种氧化锆切削行为的研究

目的研究临床常见两种不同类型氧化锆材料的耐磨性和被切削表现以及不同金刚砂车针对两种氧化锆的切削效率。方法使用Mani和RAICH金刚砂车针在匀速恒力状态下切削多色多层氧化锆(MY锆)与超透氧化锆(ST锆),并且用Micro-CT系统对体积损失部分进行扫描重建,计算两种氧化锆的体积损失,评价其耐磨性。用两种氧化锆材料的体积损失与车针质量损失之比来评价两种车针的切削效率。使用SEM观察切削前后的两种氧化锆材料和两种金刚砂车针的表面微观形貌。结果多色多层氧化锆体积损失较超透氧化锆大,且随切削深度增加而减少。多色多层锆体积损失为MY 1st=20.07 mm^(3),MY 2nd=16.73 mm^(3),MY 3rd=13.5 mm^(3)。超透氧化锆体积损失为ST=12.64 mm^(3)。耐磨性排序:ST>MY 3rd>MY 2nd>MY1st。RAICH车针平均切削效率为109.21;Mani车针的平均切削效率为110.59,经t检验,差异无统计学意义(P>0.05)。结论多层多色氧化锆越靠近浅层越容易切削,比超透氧化锆更容易切削;两种车针的切削效率基本相等。

SLM3D打印技术与失蜡铸造技术在可摘局部义齿支架制作中的应用

目的分析选择性激光熔融(SLM)3D打印技术与失蜡铸造技术在可摘局部义齿支架制作中的应用效果。方法选取2021年5月至2023年5月汉中市口腔医院收治的86例KennedyⅠ类牙列缺损患者作为研究对象,根据随机数表法将患者分为A组和B组各43例。A组采用SLM3D打印技术行可摘局部义齿支架制作,B组采用失蜡铸造技术行可摘局部义齿支架制作。两组患者于义齿佩戴1周后复诊,比较两组患者口腔内黏膜压痛点数量、义齿支架佩戴效果以及咀嚼效率;两组患者于义齿佩戴1个月后再次复诊,比较两组患者的满意度评分、主观感受评分及并发症发生情况。结果义齿佩戴1周后,A组患者口腔内黏膜平均压痛点为(0.61±0.13)个,明显少于B组的(2.23±0.21)个,A组患者吸光度值为0.61±0.05,明显高于B组患者的0.43±0.03,差异均有统计学意义(P<0.05);义齿佩戴1周后,A组患者的固位性、适合性和稳定性分别为55.81%、53.49%、58.14%,明显高于B组的30.23%、27.91%、32.56%,差异均有统计学意义(P<0.05);义齿佩戴1个月后,A组患者的主观感受评分和满意度评分分别为(28.07±2.75)分、(14.66±3.21)分,明显高于B组患者的(16.55±0.44)分、(6.68±1.32)分,差异均有统计学意义(P<0.05);义齿佩戴1个月后,A组患者的并发症总发生率为6.98%,明显低于B组患者的23.26%,差异有统计学意义(P<0.05)。结论SLM3D打印技术在可摘局部义齿支架制作中的应用效果良好,制作义齿支架较传统失蜡铸造技术偏差更小,具有更高的精确度,同时患者使用舒适度和满意度也更高,值得临床推广应用。

张口受限患者的数字化修复1例及文献回顾

目的探讨因系统性硬皮病导致的特殊张口受限(小口畸形)患者取模困难时准确得到其口内模型的方法。方法本研究遵循医学伦理,并获得患者知情同意。对1例肯氏Ⅰ类下颌牙列缺损的硬皮病张口受限患者应用以数字化技术为主导,结合传统印模方式的分段印模方案。根据其本身的左、右下颌牙列制作个别托盘后进行分段式取模,同时口内扫描取得上、下颌软硬组织形态数据。在获得各部分模型后,对下颌模型进行扫描和数字对齐,形成最终的牙列模型,并借助CAD/CAM技术设计制作最终的可摘局部义齿,同时结合文献对张口受限患者可摘局部义齿修复诊疗进行回顾分析。结果义齿固位良好,获得了良好的修复效果,患者对该义齿的咀嚼效率等功能行使均满意。文献复习结果表明,数字化技术结合传统印模方法,利用计算机进行拟合可以准确地得到患者口内模型,为后续修复做好基础工作。然而患者下颌牙列前段无牙时该流程误差可能较大,仍需要进一步完善。结论以数字化技术为主导,结合传统印模方式的分段印模方案用于修复张口受限患者的牙列缺损效果良好,患者就医体验、满意度高,值得临床推广。

二硅酸锂基玻璃陶瓷单端树脂粘接桥修复个别前牙缺失的临床应用

目的探讨二硅酸锂基玻璃陶瓷单端树脂粘接桥修复个别前牙缺失的临床效果,为个别前牙缺失修复方式的选择提供参考。方法本研究已通过单位伦理委员会审查批准,并获得患者知情同意。选取42例单颌前牙缺失数量在两颗内的患者,采用二硅酸锂基玻璃陶瓷单端树脂粘接桥修复,修复后6个月、1年、2年、3年进行随访,评价美学、功能修复效果及牙周健康状况,并采用视觉模拟评分量表(VAS)调查患者的满意度。结果观察期间,42例二硅酸锂基玻璃陶瓷单端树脂粘接桥修复的患者中有1例3个月内连接体发生断裂,1例2年内发生脱粘;美学修复效果的等级均评定为A级;修复后牙周健康状况良好,基牙及桥体下的软硬组织无临床吸收现象,评价指标均为A级;患者总满意率为100%。结论对于个别前牙缺失,二硅酸锂基玻璃陶瓷单端树脂粘接桥可达到微创、固位牢靠、美观舒适和生物相容性好的修复效果,患者满意度高,在临床中可以考虑作为一种理想的修复方式。

新构型可摘局部义齿设计制作及精度与适合性研究

目的:对可摘局部义齿进行新构型设计与制作,评估其精度及适合性。方法:在支架网状结构部分设计带基牙预备体的结构,通过分层方法,设计树脂基板颊侧与组织面,分别使用选择性激光熔融技术制作(SLM)、数字光处理技术(DLP)及数控切削技术(CNC)制作钛合金新构型可摘局部义齿支架、基托树脂部分及牙冠,拼接组装完成实验组新构型可摘局部义齿;对照组为SLM技术制作的传统设计可摘局部义齿支架,常规排牙充胶完成最终义齿。每组10个样本。采用Geomagic Warp软件的3D比较功能对两组可摘局部义齿的精度及适合性进行检测,并对结果统计分析。结果:实验组与对照组义齿支架精度3D偏差(mm)分别为0.153±0.019和0.153±0.011(P=0.978),义齿整体适合性3D偏差(mm)分别为0.191±0.006和0.187±0.007(P=0.218)。结论:新构型可摘局部义齿设计与制作过程简便,易于个性化修整,精度与适合性符合临床需求。

生物导向型牙体预备技术对修复体边缘牙周菌斑定植水平和龈沟液炎症因子水平的影响

目的:探讨运用生物导向型预备技术制备的修复体边缘牙周菌斑定植和龈沟液(GCF)炎症因子水平及临床意义。方法:纳入102例慢性牙周炎患者,随机分为2组(n=51),对照组行传统牙体预备,观察组行生物导向性预备技术。比较两组患者术前和术后6月修复体边缘骨吸收量、探诊方面的具体深度、牙龈乳头以及改良菌斑方面的具体指数、改良龈沟出血指数,在修复体位置采集龈沟液,测定TNF-α、 IL-6和MMP8水平。结果:术后6月观察组和对照组患者近中、远中及平均骨吸收量差异无统计学意义(P>0.05)。两组患者修复体牙周指数明显降低(P<0.05),且观察组患者改良龈沟出血指数、探诊深度、牙龈乳头指数和改良菌斑指数明显低于对照组(P<0.05)。两组患者龈沟液炎性因子明显降低,且观察组患者TNF-α、MMP8和IL-6明显低于对照组(P<0.05)。观察组患者舒适度、固位功能、美观度和总分明显高于对照组(P<0.05),而在咀嚼功能、语言功能方面差异未见统计学意义(P>0.05)。结论:生物导向性预备技术应用于慢性牙周炎患者,可有效改善修复体定植水平,消除龈沟液炎症反应,提高患者满意度。