Evaluation of retention forces and resistance to fatigue of attachment systems for overdentures: plastic and metal components

Novel PEEK Retentive Elements versus Conventional Retentive Elements in Mandibular Overdentures: A Randomized Controlled Trial

Background. Many patients suffer from lack of retention of conventional mandibular overdentures due to loss of clip retention over time. Computer-aided design-computer-aided manufacturing (CAD-CAM) milled polyether ether ketone (PEEK) materials may be used for the construction of retentive housing and clips for improving retention of implant-supported overdentures. Objective. To compare retention and patient satisfaction of implant-supported mandibular overdentures retained by conventional nylon clip and metal housings for ball attachments versus PEEK clip and housings. Methods. Twenty-two participants were divided into 2 equal groups (n = 11). The conventional group received implant-supported mandibular overdentures retained by metal housings and nylon retentive elements, while the PEEK group received implant-supported mandibular overdentures retained by PEEK retentive elements and housings. The PEEK retentive elements were made using computer-aided design and computer-aided manufacturing (CAD-CAM). The evaluation included measuring the retention by applying a gradual pulling up force by force meter and patient satisfaction with a 7-point visual analog scale (VAS) at overdenture insertion and 3, 6, and 12 months subsequently by a research interviewer. Results. The PEEK group showed statistically significantly increased retention force ( $P<0.05$ ) at the time of insertion (37.6/17.79) and after 3 months (33.9/16.78), 6 months (32.7/15.97), and 12 months (31.65/13.05). The conventional group had a statistically significantly higher mean overall satisfaction ( $P<0.05$ ) at the time of insertion (65/82.18). No statistically significant difference was found after 3 months (87.81/84.72). The PEEK group showed statistically significantly higher mean overall satisfaction ( $P<0.05$ ) after 6 months (86.36/80.18) and 12 months (85.45/79.54). Conclusions. According to the results of this study, the PEEK retentive material provided more retention than did the conventional material and led to improved patient satisfaction. The study was registered at clinical trials.gov (https://clinicaltrials.gov/ct2/show/NCT05079048).

Attachment-Retained Unilateral Partial Denture versus Tooth Implant-Supported Prosthesis in Mandibular Distal Extension Cases: A Randomized Controlled Trial

Objective:

To evaluate patients’ satisfaction, biting force measurement, and radiographic evaluation of abutment teeth of tooth implant-supported fixed partial denture, unilateral attachment, and conventional partial denture in mandibular distal extension cases.

Materials and Methods:

Twenty-four participants were selected according to the following criteria: participants with unilateral mandibular distal extension with last standing second premolar abutment; participants having abutments with sufficient occluso-gingival height and good periodontal condition. Participants were divided into the following three equal groups: participants of the implant group received fixed tooth implant-supported fixed partial dentures, attachment group participants received unilateral attachment removable partial dentures, and conventional group participants received conventional removable partial dentures. The evaluation included patient satisfaction using “OHIP14” questionnaires, biting force measurement, and radiographic evaluation of terminal abutments using the ANOVA test.

Results:

Participants of the implant group were mainly satisfied with their prosthesis than the attachment group, which is higher than the conventional. Regarding biting force measurement, there is a statistically significant difference (p < 0.05) between all groups, including the implant group and attachment group, as well as between attachment and conventional group (p < 0.05). The conventional group showed statistically significant (p < 0.05) highest mean bone loss, while there was no statistically significant difference between implant and attachment groups; both showed statistically significantly lower mean amounts of bone loss.

Conclusion:

The tooth implant-supported fixed prosthesis could be considered a superior line of treatment for managing distal extension cases. Unilateral attachment, which is considered an excellent alternative in the case of implant placement, is not recommended.

One-year prospective clinical study comparing patient satisfaction and masticatory performance of mandibular overdentures supported by one versus two implants

There is a lack of clinical evidence on mandibular overdentures (MOD) supported by a single implant.

In vitro retention force measurement for three different attachment systems for implant-retained overdenture

AIM

The aim of this study is to compare the retention force of three different types of overdenture attachment systems used in implant-retained mandibular complete overdentures.

MATERIALS AND METHODS

Twenty-one similar acrylic resin blocks were prepared and divided into three study groups: Group A (snap attachment) - 10 specimens, Group B (locator attachment) - 1 specimen, and Group C (syncone attachment) - 10 specimens. A single rectangular heat cure acrylic resin block with two implant analogs 22 mm apart was used with all specimens. Each specimen was subjected to 5500 cycles of insertion and removal in the presence of artificial saliva, representing 5 years of usage. Retention was measured three times for each specimen using universal testing machine. Data were analyzed using one-way and two-way analysis of variance at 95% level of confidence.

RESULTS

Locator attachment group (Group B) showed the greatest retention level throughout the study, followed by snap attachment (Group A), and syncone attachment (Group C) showed the lowest retention level.

CONCLUSION

Regardless of the initial retention level of overdenture attachment, gradual loss of retention values is inevitable. However, the rate of retention loss in overdenture attachments is higher in types which comprised plastic parts within their components, rather than those totally made up of noble metals.