Retentive force and dislodgment time variations between three implant overdenture stud attachments in an acidic environment: An in-vitro pilot study.

Introduction: This in-vitro study aimed to evaluate the retentive force and dislodgment time of three stud attachment systems used for mandibular two-implant overdentures by simulating insertion/removal cycles. Materials and methods: From a simulation of a completely edentulous mandible with two parallel implants (Ø4.5 mm internal hex connection) (Zimmer Biomet, Warsaw, IN), 15 resin bases were fabricated and divided into three groups (n = 5 each): OT Equator (Rhein83, Bologna, IT), Locator (Zest Dental Solutions, Escondido, CA) and Locator R-Tx (Zest Dental Solutions, Escondido, CA). Pink inserts underwent 2000 cycles of thermocycling (SD MECHATRONIK GmbH, Feldkirchen-Westerham, Germany) and were soaked in citric acid for 24 days in an incubator. Each base underwent 2000 insertion/removal cycles on the Versa Test testing machine (Mecmesin Ltd., W. Sussex, UK) which was used to measure the retentive force and dislodgment time. The results were analyzed using ANOVA followed by the post-hoc Tukey test, Kruskal-Wallis test, and Pearson correlation coefficient test. A p-value of < 0.05 was considered statistically significant. Results: The retentive force and dislodgment time of the three systems significantly decreased over the cycles (p < 0.05). The Locator R-Tx showed significantly greater retentive force ​​than did the other systems (p < 0.05), except for the last cycles wherein no significant difference was found with the OT Equator (p > 0.05). The OT Equator had the most stable retention over the cycles (p > 0.05; cycle 1500). Conclusion: The three systems showed satisfactory retentive force ​​during the 2000 cycles. The Locator R-Tx demonstrated the best retention, while the OT Equator exhibited the most stable retention over time.

Masticatory efficiency of implant-supported mandibular overdentures retained with attachments compared with conventional dentures: an in vitro digital colorimetric image analysis.

Despite the patient-reported advantages of implants in improving quality of life, satisfaction, and mastication, objective evaluations of the masticatory function and performance of implant-supported dentures are not well represented in the literature. The aim of the present study was to compare the masticatory efficiency of patients with conventional dentures with that of patients with mandibular overdentures retained by implants with 2 Locator attachments. A randomized clinical trial including 20 edentulous patients was conducted. The participants were randomly recruited into 2 groups, a group of 10 patients wearing conventional prostheses in both the maxilla and mandible, and a group of 10 patients wearing a conventional maxillary prosthesis opposite an implant-supported overdenture. To be included in the study, the patients had to have a well-formed ridge (Class I according to the Atwood classification). Their masticatory efficiency, assessed a minimum of 6 months after they received the denture, was evaluated through a color-mixing test using 2 colors of a commercially available chewing gum and ViewGum software, which calculated the variance of hue in the masticated specimens. The masticatory efficiency of the 2 groups was compared using repeated-measures analysis of variance (α = 0.05), which revealed no statistically significant difference between the implant-supported overdenture and conventional denture groups (P > 0.05). Within the limits of this study, the results suggest that a mandibular implant overdenture has no advantage over a conventional complete denture with regard to masticatory efficiency or food comminution in patients who have a well-formed mandibular ridge.

Retentive force variations of stud attachments for implant overdentures.

Implant overdentures are considered a standard treatment option by many practitioners, especially for edentulous mandibles. Stud attachments have been used extensively in the construction of these overdentures. In this study, the retentive forces of O-ring/ball and Locator overdenture attachments under various conditions in the mouth were investigated through pull-out tests. In dry testing, the retentive forces of the O-ring/ball attachment started higher than those of the Locator attachment but significantly decreased after 50 insertion-removal cycles (P = 0.014). The Locator attachment had no significant change in its retentive force over time (P = 0.328). In wet testing, a saliva substitute was applied to the stud attachments between cycles. The retentive force of the O-ring/ball attachment increased significantly in wet testing compared to dry testing (P < 0.0001). The retentive force of the Locator system during wet testing did not change significantly from that achieved during dry testing for the first 80 cycles, but then it increased to reach the same levels as the O-ring/ball system at 510 cycles (P < 0.05). Within the limitations of the present study, the results suggest that it is advisable to avoid using O-ring/ball attachments as anchors for implant overdentures in a dry mouth environment. In such cases, Locator attachment or metal-to-metal attachment components would be preferable as implant overdenture anchors. In a saliva-irrigated mouth, there is no significant difference between the retentive properties of the O-ring/ball and Locator attachments over 6-9 months' use.

Immediate loading of implants and fixed complete dentures: a simplified prosthetic procedure.

The immediate placement of fixed prostheses after the surgical phase is a challenge for prosthodontists using the All-on-four method. This article describes a simplified technique for constructing a conventional complete denture ahead of the surgery date and adapting it to the implants by using a laboratory reline procedure. This technique accommodates the immediate placement of the fixed prosthesis after surgery without compromising the quality of the prosthesis, requiring only a simple dental laboratory procedure.

The Bennett angle. Clinical comparison of different recording methods.

The use of interocclusal records with semi-adjustable articulators has been proposed as an easier alternative to axiograph. The operator measured the Bennett angle of 30 participants using an axiograph Quick-Axis, an arcon Whip-Mix and non-arcon Dentatus articulators. Wax and polyether interocclusal recording materials were used with both types of articulators. Compared to the reference axiograph, the Whip-Mix plus wax combination was the nearest one and the Dentatus plus polyether was the most significantly different combination.

Simplified method for recording maxillomandibular relations in complete dentures.

A simplified technique for recording maxillomandibular relations in complete dentures is described. This technique enables the practitioner to construct a mandibular occlusal mini-rim directly in the mouth, to adjust it to the required vertical dimension and to record the maxillomandibular relations during a single appointment. The mandibular record is formed with wax, used to hold the occlusal vertical dimension anteriorly, and impression plaster, to record the centric relation posteriorly.

The horizontal condylar inclination: clinical comparison of different recording methods.

Various types of semi-adjustable articulators (arcon and nonarcon), in combination with different interocclusal recording materials (wax and polyether), have been proposed as an easier alternative to extraoral tracing devices or axiographs. There is no consensus as to which combination is the nearest to the recognized standard extraoral tracing devices. This trial measured differences in performance among four combinations of interocclusal recordings in calculating the horizontal condylar inclination (HCl). The mean HCI measurement obtained by axiograph was 50.3 degrees (SD = 10.2) for the right condyle and 52.5 degrees (SD = 9.3) for the left. Of the four tested combinations, the arcon Whip Mix with wax was most likely to reproduce HCI values obtained using the axiograph.