RESUMEN
PURPOSE: To test the retention of two different overdenture attachment matrices and straight abutments when implants are placed at 0-, 15-, and 30-degree diverging angulations as well as the retention of 15-degree-angled abutments to correct the overall angulation to 0-degrees. MATERIALS AND METHODS: Matching aluminum blocks were machined to incorporate two dental implants at 0-degree, 15-degree, and 30-degree relative angulations and overdenture attachments to simulate a two-implant overdenture. At 0-degree, 15-degree, and 30-degree implant angulation, straight abutments were studied. At 30-degree implant angulation, an additional group was compared utilizing 15-degree angulated abutments that corrected the overall implant angulation to 0-degrees. A custom-designed testing apparatus that allowed automated insertion and removal of the simulated overdenture was designed, with three independent testing stations, each consisting of one simulated arch and one simulated overdenture base. The baseline and residual retention forces after 30,000 dislodging cycles of the simulated overdenture were measured. One-way ANOVA was used to compare retention differences among different color patrices within the 0-, 15-, and 30-degree implant angulation groups followed by Tukey's multiple comparison test. Two sample t-tests were used to compare 0-degree versus 15-degree implant groups with straight abutments and 30-degree implant groups with straight abutments versus 30-degree implant groups with angulated abutments. RESULTS: Regardless of implant angulation or abutment correction, the change in retention exhibited by the Novaloc system after testing was not statistically significant for all patrice types (p > 0.05); however, the change in retention exhibited by the Locator system was statistically significant for the tested group (p = 0.0272). In both the Novaloc and Locator systems, the baseline and final retention values provided by the different patrices were significantly different except for the white and green Novaloc patrices in the 15-degree divergent implant group which did not meet the specified level of significance (p = 0.0776). CONCLUSION: Within the limitations of this study, implant angulations upto 15 degrees do not affect differential change in retention of Novaloc patrices. There is no difference between Novaloc white inserts (light retention value) and green inserts (strong retention values) when implants diverge upto 15 degrees. When Novaloc straight abutments were placed on implants diverging by 30 degrees, blue extra-strong retention inserts outperformed yellow medium retention inserts by maintaining a higher retention value after 30,000 cycles. When utilizing Novaloc 15-degree angulated abutments that correct the overall implant angulation to zero degrees, the red light retentive patrice provides steady retention. Finally, the Locator-green patrice system provides greater retention than the comparable Novaloc-blue patrice combination; however, it also loses more retention after 30,000 cycles.
RESUMEN
Aim: This systematic review aimed to compare different attachment systems used in mandibular implant supported overdentures by assessing outcomes such as prosthodontic maintenance and complication, peri implant tissue changes, retention, and patient satisfaction for optimum selection of attachment system. Settings and Design: This systematic review conducted following Preferred Reporting Items for the Systematic Review and Meta Analysis (PRISMA) guidelines. Materials and Methods: A systematic electronic literature search was conducted through PubMed, The Cochrane Central Register of Controlled Trials (Central), and Science direct. A hand search was also performed for individual journals and reference lists of selected studies. Randomized controlled clinical trials and crossover clinical trials from 2010 to 2020 with follow up of more than 1 year were included. The Cochrane Collaboration's tool was used for assessing the risk of bias of included studies. Statistical Analysis Used: The statistical meta analysis was performed using Review Manager (RevMan) [computer program]. Version 5.4. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboation, 2020. Results: Six studies that met the inclusion criteria possess the low risk of bias with follow up of more than 1 year were included in this systematic review. Out of four outcomes, meta analysis was performed for prosthodontic maintenance and peri implant tissue changes. Due to the limited availability of data, retention and patient satisfaction were reviewed systematically without meta analysis. The result of meta analysis for ball versus magnet attachment showed statistically significant differences in prosthodontic complications and maintenance, and ball attachment reported fewer complications than the locator attachment (risk ratio [RR] =0.55, confidence interval [CI] =95%, P = 0.03). Peri implant tissue changes were analyzed in the included studies as probing depth and marginal bone loss. The result of meta analysis for probing depth showed no statistically significant difference between bar versus telescopic type of attachment (RR = 0.20, CI = 95%, P = 0.74). The meta analysis results for marginal bone loss showed no statistically significant difference between bar versus telescopic type of attachment (mean difference = 0.35, CI = 95%, P = 0.10). Conclusion: It can be concluded from the current review that bar attachment provided the most superior retention. The telescopic attachment system not only showed the most favorable patient's satisfaction but also reported the least peri implant mucosal changes. The ball attachment system is a favorable choice for limited inter arch space and parallel implant placement.