Effect of simulated masticatory loading on the retention of stud attachments for implant overdentures

Abstract

This study assessed the effect of simulated mastication on the retention of two stud attachment systems for 2-implants overdentures. Sixteen specimens, each simulating an edentulous ridge with implants and an overdenture were divided into two groups, according to the attachment system: Group I (Nobel Biocare ball-socket attachments) and Group II (Locator attachments). Retention forces were measured before and after 400,000 simulated masticatory loads in a customised device. Data were compared by two-way anova followed by Bonferroni test (α = 0·05). Group I presented significantly lower retention forces (Newtons) than Group II at baseline (10·6 ± 3·6 and 66·4 ± 16·0, respectively). However, differences were not significant after 400,000 loads (7·9 ± 4·3 and 21·6 ± 17·0). The number of cycles did not influence the measurements in Group I, whereas a non-linear descending curve was found for Group II. It was concluded that simulated mastication resulted in minor changes for the ball attachment tested. Nevertheless, it reduced the retention of Locator attachments to 40% of the baseline values, what suggests that mastication is a major factor associated with maintenance needs for this system.

Effect of Different Bar Attachment and Clip Materials on Retention Force for Mandibular Implant Supported Overdentures (An Invitro Study)

“…(Table 1, 2), (Fig 5, 6). (20) These retention forces are similar to the results of ball attachments (21) and approximates the range measured for other bar systems using POM clips. (15,22) With other studies, much higher values of 20 N up to 35 N were reached using POM or metal clips on bars (14,23) So, differences of retention.…”

In Vitro Study of Retention of Paired Press-Stud Overdenture Component Attachments

“…Future research should compare overdenture attachments from several manufacturers, have a range of vertical inclinations of the paired attachments from 0° to 30°, employ an instrumented tool that enables a constant tightening torque when making adjustments, utilize a larger number of uniting/separating cycles simulating up to 5 years of patient use, and compare the use of dry and wet testing environments. Scanning electron microscope observations of the wear of the male and female stud components, similar to those performed by Abi Nader et al [13] are recommended, complemented by strain energy measurements in the manner of Petropoulos and Mante [14], at periodic intervals during the uniting/separation cycles. One would anticipate that the changes in strain energy would be correlated with the amount of wear.…”

“…The purpose of this in vitro study was to investigate the possible effect of repeated separation and reunion cycles on the retention of paired overdenture stud attachment assemblies set in acrylic resin. The present results are compared to those reported in other studies [9][10][11][12][13][14], providing some insight into these concerns and the major factors involved. …”

“…While a large increase in the seating/unseating force was observed during the first 300 cycles, no significant difference was found between the initial and final values of seating/unseating force, suggesting that use of substantially more than the 1000 testing cycles would not have altered the results of the present study. Although one limitation of this study was its in vitro nature, with ambient conditions and the absence of a lubricant, this protocol has also been followed in some of the recent studies [10][11][12][13][14] of overdenture retention. Two of these investigations have employed artificial saliva at room temperature [11] or water at 37°C [12] for the testing environments.…”

Titanium Nitride and Nitrogen Ion Implanted Coated Dental Materials

“…After 1 year of clinical use, TiN coated attachment systems appeared unchanged while extensive wear was evident in uncoated systems [47]. Wear decreases the retention force of attachments, causing discomfort to the patient and increasing the maintenance needs of removable prosthetic restorations [49]. The last application of TiN coating in implant dentistry is the covering of retentions screws for implant supported crowns [50].…”