Retention systems for implant-retained overdentures

Attachment systems for mandibular implant-supported overdentures: A systematic review and meta-analysis of randomized controlled trials

STATEMENT OF PROBLEM

Although mandibular implant-supported overdentures have been highly recommended as a treatment option, a consensus on the type of attachment systems that can be used to increase implant and prostheses survivability is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare different types of attachments for retention by investigating outcome measures such as implant and prosthesis survival rates and biological and prosthesis complications in participants with a mandibular implant-supported overdenture.

MATERIAL AND METHODS

The search was performed in the PubMed, Cochrane, Embase, and Scopus databases by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria and registered with the International Prospective Register of Systematic Reviews (CRD42021253566). An analysis of association was conducted between different attachment systems and implant and overdenture survival rates in randomized controlled clinical trials.

RESULTS

The initial search indicated 477 studies, of which 25 randomized controlled trials (RCTs) were included for analysis. A total of 2154 implants and 737 overdentures were analyzed in the meta-analysis. The main results indicated the failure rate for dental implants to be 2.0% (95% confidence interval [CI], 1.3 to 3.2) and overdentures 4.2% (95% CI, 1.6 to 10.5), respectively. With regard to different attachment systems, a similar failure rate was identified with bar-type retention (7.7% to 95% CI, 3.0 to 18.1), magnetic retention systems (7.6% to 95% CI, 2.2 to 22.7), and ball-type retention (6.8% to 95% CI, 3.0 to 14.3). No significant difference was found in biological complications for splinted and unsplinted implant overdentures (P=.902). Regarding prosthetic complications, the most favorable groups were LOCATOR attachments followed by telescopic and Conus, bar, and ball attachments. Magnet attachments had higher prosthetic complications (7.4 times) than the other attachments.

CONCLUSIONS

Implants and implant-supported mandibular overdentures showed a high survival rate irrespective of the attachment system used. Splinting implants did not significantly affect the rate of biological complications. Prosthetic complications were most common for magnet and least common for LOCATOR attachments.

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.

Biomechanical Aspects of Various Attachments for Implant Overdentures: A Review

There have been considerable recent technological developments for implant overdenture attachments. This study presents an overview of the biomechanical and biomolecular aspects of various attachments for implant overdenture. Available articles on attachments for implant overdenture were reviewed from January 1980 to August 2021 in the ScienceDirect, MEDLINE/PubMed, and Web of Science resources, and relevant studies were included in this study. We focused on the following topics: attachment systems, retention of various attachments, stress distribution with different attachments, the design and fabrication of attachments, digital techniques in overdenture attachments, and the effects of attachments in peri-implant health. We found that plastic resin is commonly used for ball and bar attachments, whereas nylon resin is commonly used in locator attachments. The locator system offers a valuable attachment option for implant-retained overdenture. Attachment retention reduces while lateral force increases with implant inclination in overdenture. The higher the retention of an overdenture attachment, the higher the transferred stresses. Additionally, clip loading produces more stress in implants and precision elements than bar-retained dentures. As such, we conclude that the ball and locator systems the best overdenture systems due to their superior tissue response, survival rate, and patient satisfaction.

Biomechanical Aspects of Various Attachments for Implant Overdentures: A Review

There have been considerable recent technological developments for implant overdenture attachments. This study presents an overview of the biomechanical and biomolecular aspects of various attachments for implant overdenture. Available articles on attachments for implant overdenture were reviewed from January 1980 to August 2021 in the ScienceDirect, MEDLINE/PubMed, and Web of Science resources, and relevant studies were included in this study. We focused on the following topics: attachment systems, retention of various attachments, stress distribution with different attachments, the design and fabrication of attachments, digital techniques in overdenture attachments, and the effects of attachments in peri-implant health. We found that plastic resin is commonly used for ball and bar attachments, whereas nylon resin is commonly used in locator attachments. The locator system offers a valuable attachment option for implant-retained overdenture. Attachment retention reduces while lateral force increases with implant inclination in overdenture. The higher the retention of an overdenture attachment, the higher the transferred stresses. Additionally, clip loading produces more stress in implants and precision elements than bar-retained dentures. As such, we conclude that the ball and locator systems the best overdenture systems due to their superior tissue response, survival rate, and patient satisfaction.

Effect of 2-implant mandibular overdenture with different attachments and loading protocols on peri-implant health and prosthetic complications: A systematic review and network meta-analysis

STATEMENT OF PROBLEM

A systematic review of the effect of different overdenture attachments with different loading protocols on peri-implant health is lacking.

PURPOSE

The purpose of this systematic review and network meta-analysis was to evaluate the effect of different overdenture attachments with delayed or immediately loaded 2-implant-retained mandibular overdentures on peri-implant tissue health.

MATERIAL AND METHODS

A comprehensive search of the PubMed, EMBASE, and Cochrane library was conducted to identify eligible randomized controlled trials (RCTs). The outcomes were marginal bone loss, probing depth, plaque index, bleeding on probing, implant survival rate, and prosthetic complications. The Bayesian network meta-analysis accompanied by a random effect model and 95% credible intervals was calculated.

RESULTS

Sixteen RCT (n=599 participants receiving 1198 dental implants) were included. Five common overdenture attachment systems with delayed or immediate loading were compared. The difference in marginal bone loss and probing depth was not statistically significant when comparing different overdenture attachments with different loading protocols. The rank probability test showed that bar+ immediate loading ranked highest (63.8%) in terms of marginal bone loss, whereas ball+ delayed loading (73.3%) ranked highest in terms of probing depth. The implant survival rate was 100% for the LOCATOR+ delayed loading, resilient telescopic+ delayed loading, and magnet+ immediate loading; however, bar+ delayed loading, ball+ delayed loading, magnet+ delayed loading, LOCATOR+ immediate loading, ball+ immediate loading, and bar+ immediate loading had survival rates of 99.1%, 98.8%, 96.0%, 94.7%, 93.1%, and 91.2%, respectively.

CONCLUSIONS

All types of overdenture attachment with immediate loading or delayed loading had a similar effect on peri-implant health. Bar+ immediate loading was associated with the least marginal bone loss, whereas ball+ delayed loading showed the least probing depth.

Shrinkage characteristics of a novel lower contractile acrylic pattern resin

Forming models and brazing parts, both of which require high accuracy, are greatly affected the polymerization shrinkage of pattern resin. In 2018, a lower-shrinkage autopolymerizing pattern resin (PRK) was introduced. In this work, we compared the rate of polymerization shrinkage between PRK with that of three autopolymerizing resins -GC Pattern Resin (GPR), Pi-Ku Plast (PIK), and Fixpeed (FIX)- as controls. The shrinkage percentages at 10 min were 7.26±0.88 for PRK, 10.78±2.28 for GPR, 8.03±1.08% for PIK, and 7.46±1.25 for FIX. The shrinkage of PRK was significantly lower than that of GPR. The lower-shrinkage autopolymerizing resin contains some multifunctional monomer and indicated that the amount of monomer was accordingly reduced from the result of polymer size and abundance ratio. Our results suggested that the monomer component and the polymer particle size were factors that contribute to reducing contraction of the resins.

Implant retention systems for implant-retained overdentures

Implant retained overdentures are being increasingly utilised in both general and specialist practice to rehabilitate patients with missing teeth, particularly those that are edentate. This article aims to inform the reader of a variety of retention systems that are available to retain an implant overdenture and to understand how these systems work, their advantages and disadvantages and to outline some of the clinical and treatment planning considerations involved in selecting the most appropriate retention system for patients.

An Implant-Retained Obturator – A Case Study

This case describes the oral rehabilitation of a patient following maxillary hemi-section due to squamous cell carcinoma of the palate. Planned treatment was construction of a maxillary implant-supported obturator. Two dental implants were placed in his maxilla to aid the support and retention of an obturator. However, owing to bone availability, their angulation was suboptimal and compromised the retention of the obturator. This case describes alternative implant attachments to aid the retention and stability of implant-retained dentures constructed in cases with suboptimal implant placement. Clinical relevance: This case highlights the importance of careful planning for implant placement, and reinforces the need to plan the prostheses before implant surgery. This case highlights possible difficulties that can arise if implants are non-ideally angulated, and how to adapt restorations to manage such difficulties in cases with maxillary removable prostheses.