Management of Maxillary Cluster Implant Failures with Extra‐Maxillary Implants: A Clinical Report

Late cluster implant failures can be one of the most devasting outcomes of implant therapy for patients. It can have anatomic, functional, psychological and financial consequences for patients, and sometimes the loss of residual bone can preclude subsequent implant placement. Fortunately, management of cluster implant failures in the maxilla can be mitigated by using implant anchorage from remote sites like zygomatic and pterygoid regions. Few reports exist in the literature that have described the management of cluster implant failure using extra‐maxillary implants such as zygomatic and pterygoid implants. This case report describes the management of a female patient with bruxism who experienced late cluster implant failure in the maxilla after 9 years of function with an overdenture. Due to the loss of residual bone, subsequent implant therapy involved the use of bilateral zygomatic, pterygoid and anterior maxillary implants, which were immediately loaded and thereafter used to support a complete arch fixed implant‐supported zirconia prosthesis.     

Digital Workflow for Retrofitting a Surveyed Crown Using a Removable Partial Denture as an Antagonist

Digital workflow expedites the procedure of retrofitting a surveyed crown against an existing removable partial denture (RPD). This article describes a simple and straightforward technique of digital workflow where an existing RPD is scanned as an antagonist to design the rest seat, guide plane, and height of contour of a surveyed crown.     

整体切削的聚醚醚酮可摘局部义齿即刻修复1例

聚醚醚酮(PEEK)是一种具有良好的力学性能和生物安全性的新型高分子化合物,近年来逐渐应用于口腔修复、种植、正畸等领域。目前,PEEK在可摘局部义齿中的应用已有临床报道,但整体切削的PEEK可摘局部义齿还未见相关临床报道。本病例应用全程数字化设计和PEEK材料,整体切削制作了集支架、人工牙和基托为一体的可摘局部义齿,对1例83岁上下颌牙列缺损的患者进行了即刻修复治疗,并进行了3~6个月的随访,患者对修复效果满意。     

Novel fully digital workflow for removable partial denture fabrication

PurposeThis technical procedure report introduces a newly developed method for removable partial denture (RPD) fabrication using computer-aided design and computer-aided manufacturing (CAD/CAM) and rapid prototyping (RP) technologies.MethodsFull-arch digital impressions of the partially edentulous jaw were made by an IOS or the conventional method. The denture framework, artificial teeth, and denture base were designed by commercially available CAD software. Each of the denture components including connectors, clasps, and artificial teeth and the denture bases were fabricated separately by the CAM machine or the three-dimensional (3D) printer, and then assembled using an adhesive material.ConclusionsRPDs were successfully fabricated using fully digital workflow and delivered to the patient, and no clinical complications were reported. Within the limitations of this report, the newly developed RPD fabrication techniques have the potential to change clinical and laboratory workflow from analog to digital.     

Flexible Removable Partial Denture Prosthesis: A Survey of Dentists’ Attitudes and Knowledge in Greece and Croatia

Purpose

The aim of this study was to investigate through a questionnaire the knowledge, attitudes and possible differences in the use of flexible RPDPs among dentists in Greece and Croatia.

Material and Methods

A questionnaire of 16 questions was originally created in English, translated into Greek and Croatian language following a two way translation and tested for apprehension, precision, clarity and homogeneity by a number of native English speaking Greek and Croatian dentists. Following the necessary corrections, the questionnaires replicated in two online surveys and their addresses with an informed consent were sent by emails to nearly 4000 dentists in each country to participate. Collected data were analyzed by chi-square tests at a= .05 level of significance.

Results

378 dentists from Greece and 304 from Croatia participated in the study. 137(36.2%) dentists from Greece and 56(18.4%) from Croatia provided flexible RPDPs to their patients. Statistical analysis for all providers indicated no significant difference between genders (P>.05), significant differences between age groups (P<.01), years of practice (P<.05), specialization (P <.001), and instruction on flexible prostheses (P <.001). The analysis between the two countries showed differences for gender and age groups (P<.01) but no differences between experienced, specialized or instructed groups (P >.05).

Conclusion

The survey indicated differences between the two countries in the percentages of dentists using, selecting and providing RPDPs for their patients. Practitioners’ age, years in practice and instruction were associated with the provision of the prostheses, while comfort, esthetics and cost were the reasons for deciding to use the flexible RPDPs.

Conclusion

Although dentists are not educated in their schools about flexible RPDPs, almost a third of them offer this treatment to their patients. Long term success of these devices depends on clinical education, more experience and definitely more research.     

200例正常成人鼻腭管解剖形态的锥形束CT研究

目的 评估正常成人鼻腭管在锥形束CT图像中的位置及形态.方法 收集200个正常成人上颌骨前牙区锥形束CT扫描数据.扫描曝光和头颅定位均使用标准条件.由两名放射科医生进行锥形束CT图像中鼻腭管的位置、形态和尺寸的评测.结果 200例正常成人鼻腭管结构的正中矢状面形态可分为5型.切牙孔水平的轴面形态常见为3类,分别为类圆形、类三角形及泪滴状.鼻底水平以1～2个开口居多,但有时也可见3个开口.鼻腭管的位置和尺寸相关测量项目在不同矢状面形态分类及不同轴面形态分类中存在差异.结论 在锥形束CT图像中,正常成人鼻腭管在多个层面的形态及直径等方面存在一定的解剖变异.     

A finite element study on stress distribution of two different attachment designs under implant supported overdenture

Objective

This study aimed to evaluate stress patterns generated within implant-supported mandibular overdentures retained by two different attachment types: ball and socket and locator attachments.

Materials and methods

Commercial CAD/CAM and finite element analysis software packages were utilized to construct two 3D finite element models for the two attachment types. Unilateral masticatory compressive loads of 50, 100, and 150 N were applied vertically to the overdentures, parallel to the longitudinal axes of the implants. Loads were directed toward the central fossa in the molar region of each overdenture, that linear static analysis was carried out to find the generated stresses and deformation on each part of the studied model.

Results

According to FEA results the ball attachment neck is highly stressed in comparison to the locator one. On the other hand mucosa and cortical bone received less stresses under ball and socket attachment.

Conclusions

Locator and ball and socket attachments induce equivalent stresses on bone surrounding implants. Locator attachment performance was superior to that of the ball and socket attachment in the implants, nylon caps, and overdenture. Locator attachments are highly recommended and can increase the interval between successive maintenance sessions.