Effect of LOCATOR attachments with different retentive forces on the stability of 2-implant-retained mandibular overdenture

Quantitative and qualitative assessment of the wear pattern of two attachment systems of dissimilar materials for mandibular implant-retained overdentures: an in-vitro study

BACKGROUND

Attachment material is one of the contributing factors to the degree of wear of the attachment components in mandibular implant-retained overdentures. The purpose of this in vitro study was to compare the wear behavior of 2 different attachment systems of dissimilar materials in mandibular implant-retained overdentures by qualitative and quantitative methods.

METHODS

Two attachment systems of different materials were utilized (n = 16); Titach (Dental Evolutions Inc, Beverly Hills, CA, USA) with a titanium-to-titanium interface and Locator R-Tx (Zest Anchors Inc, Escondido, CA, USA) with a titanium-to-nylon interface. One thousand cycles of overdenture insertion and removal simulating 1-year clinical use were performed. All matrices were removed from the overdentures and all patrices were unscrewed from the implants for wear assessment quantitively using a stereomicroscope and qualitatively using a scanning electron microscope. Data were analyzed by using an independent sample t test.

RESULTS

After cyclic loading, stereomicroscopic findings showed that the Titach group had statistically significant higher wear value than the Locator R-Tx group (p < 0.001). Moreover, scanning electron microscopy images showed noticeable abrasion in Titach patrix at the area of highest convexity. However, the Locator R-Tx matrix displayed an apparent tear of rubber inserts.

CONCLUSIONS

Titach attachment with the titanium-to-titanium interface revealed more wear than Locator R-Tx attachment with the titanium-to-nylon interface. Thus, the type of attachment material influences the degree of wear of the attachment components.

Effect of mastication load on retention force of custom-made LOCATOR abutments manufactured for angled implants: An in vitro study

STATEMENT OF PROBLEM

Custom-made angled LOCATOR abutments have been used to compensate for the angulation of implants placed to support removable prostheses; however, their retention forces and the impact of mastication loading on retention have yet to be well addressed.

PURPOSE

The purpose of this in vitro study was to evaluate the retention force of custom-made LOCATOR abutments for implants placed at 0-, 15-, and 30-degree angulations with prefabricated abutments and to investigate the effect of mastication load on retention.

MATERIAL AND METHODS

Implant analogs were placed at the first molars of 40 maxillary typodonts, and 40 LOCATOR abutments were fabricated. Twenty implant analogs were placed at 0 degrees, 10 of which received prefabricated LOCATOR abutments and 10 of which received custom abutments. The remaining 20 implant analogs were placed at 15- and 30-degree angulations (n=10), and custom LOCATOR abutments were fabricated on them. A denture analog was digitally designed and manufactured from polymethyl methacrylate (PMMA) billets. Metal housings were then picked up using PMMA. The specimens were subjected to 2 rounds of 120 000 cycles of mastication loading. Retention force was assessed before and after each round of mastication loading using a universal testing machine. The wear of nylon inserts before and after mastication loading was accessed with a digital stereomicroscope. A 2-way ANOVA followed by the Tukey HSD test was used to determine the impacts of LOCATOR abutment type and times of mastication loading on the retention forces of the denture base (α=.05).

RESULTS

No significant difference in retention forces was found between prefabricated LOCATOR and custom abutments (placed at 0-, 15-, and 30-degree angulations) regardless of mastication loading (P>.05). The retentive force values of all groups increased significantly after the first round of mastication loading and decreased significantly to the initial level after the second round of mastication loading (P<.05).

CONCLUSIONS

Mastication loading impacted the retention force of both prefabricated and custom LOCATOR abutments; however, no significant difference in retention forces was found among various types of abutments.

Effect of simulated toothbrushing on the surface roughness of LOCATOR abutments: An in vitro study

STATEMENT OF PROBLEM

Studies evaluating the effect of toothbrushing and toothpaste abrasivity on the surface roughness of LOCATOR abutments are lacking.

PURPOSE

The purpose of this in vitro study was to compare the surface roughness of LOCATOR abutments before and after simulated toothbrushing with different toothpastes to make recommendations for the home care of patients with LOCATOR abutments.

MATERIAL AND METHODS

LOCATOR bone-level overdenture abutments (N=36) were analyzed with a confocal laser scanning microscope (Keyence VK-X1100) at ×5 magnification. Surface scans were made to determine the degree of surface roughness (Ra). Two toothpastes of different abrasivity (Colgate Total and Crest ProHealth) and deionized water were used as the brushing media (n=12). Each toothpaste was mixed with water in a 1:2 ratio. The abutments were brushed using soft nylon toothbrushes for 30 000 cycles in a ZM-3.12 toothbrushing simulator, which has been interpreted as 3 years of regular use. All specimens were then reanalyzed under the microscope. Changes in surface texture were compared by using a repeated measures analysis of variance (ANOVA) statistical test and a pairwise Šídák multiple comparisons test (α=.05).

RESULTS

The mean surface roughness value of LOCATOR abutments at baseline ranged between 1.34 µm and 1.35 µm. After 30 000 cycles of toothbrushing simulation, the mean value increased to 1.62 µm (DI water, P=.001), 1.74 µm (Colgate Total, P<.001), and 2.03 µm (Crest ProHealth, P<.001). All brushing media resulted in a statistically significant increase in surface roughness (P<.001).

CONCLUSIONS

LOCATOR abutments demonstrated significant increases in surface roughness after being subjected to toothbrushing, regardless of the brushing medium. Whitening toothpaste caused significantly more surface roughness than nonabrasive toothpaste and deionized water. Deionized water resulted in the lowest increase in surface roughness.

The effect of ball versus locator attachment system on the performance of implant supported overdenture: A systematic review

Objective

This systematic review was aimed to compare ball and locator attachment system on the basis of clinical and biomechanical performance of implant supported overdenture as well as biological and patient related outcomes.

Material and methods

Open and free electronic and manual searches were performed in digital databases including MEDLINE via PubMed, the Cochrane Database of Clinical Trials, and Scopus along with some other reliable sources. From the 667 retrieved records, 11 full-text controlled trials were included in this study. Risk of bias was assessed according to RoB 2.0 except for one RCT (economic evaluation), only assessed by CASP checklist.

Results

From the 11 retrieved studies, total 183 locator and 219 ball attachments were identified in 452 subjects of 30 yrs-95 yrs of age. Studies provided data about prosthodontic complications or maintenance (replacement or the activation of matrix and patrix part, loss of retention, fracture and relining of the prosthesis, fracture of the attachment and the survival probability), oral health impact profile, soft tissue parameters and periodontal complications, marginal bone loss, patient related outcome and cost of the attachment systems. Only 5 studies were assessed at low risk bias, while other 6 at moderate to high risk of bias.

Conclusion

Locator attachment system show lesser complications including loss of retention and lower maintenance appointments, lesser soft tissue, and periodontal complications than the ball attachment. Ball is better in terms of cost effectiveness. In other related outcomes, no significant differences were noted between ball and locator attachment.

Factors influencing retention and durability of attachments for overdentures - adverse effects of cleansings, pH, and temperature: A systematic review

Aim

The objective of this systematic review is to show the current state of the art on which type of attachment loses retention the most and has reduced durability and which factor causes these problems the most.

Material and methods

This review followed the Preferred Reporting Items for Systematic Review and MetaAnalysis (PRISMA) guidelines and it was registered with the Open Science Framework (OSF) (osf.io/2e3q5). The databases used for the electronic search of articles were Pubmed, Science Direct, Embase, and Scopus. Articles were selected by 2 independent reviewers according to the inclusion criteria. The risk of bias was analyzed by using the Joanna Briggs Institute (JBI) adapted quasi-experimental study evaluation tool.

Results

The studies included in this review indicate that the use of cleansing solutions, high temperatures, and a more acidic pH decrease the durability of the attachments, mainly due to the loss of retention that occurs in different models and materials of the attachments, which requires their replacement in a shorter period.

Conclusion

Of all the factors studied, the cleansing solutions proved to be the factor that most altered attachment retention. Different saliva compositions did not influence retention values. Aging changes retention values for attachments, mostly with loss of values.

In vitro assessment of polyetheretherketone for an attachment component for an implant-retained overdenture

STATEMENT OF PROBLEM

Frequent maintenance because of the limited lifetime of overdenture attachments with O-rings has led to the development of materials that might improve their functionality and longevity. However, testing of newly developed attachment materials is lacking.

PURPOSE

The purpose of this in vitro study was to evaluate a newly developed attachment made of polyetheretherketone (PEEK) for an implant-retained overdenture.

MATERIAL AND METHODS

Specimens of PEEK, polyacetal, and Teflon O-ring materials were prepared for analysis of roughness, surface hardness, and compressive strength. For the fatigue resistance test, new specimens based on acrylic resin were subjected to 2880 insertion and removal cycles. Compression and roughness data were compared with the Kruskal-Wallis and Dunn post hoc test; hardness data with ANOVA and t test; and fatigue and stereomicroscopy with ANOVA with repeated measures, t test, and Bonferroni adjustment (α=.05).

RESULTS

Polyacetal had the lowest surface roughness (P=.038). There was a significant difference in hardness among the materials (P<.05). PEEK presented the highest compressive strength among the materials (P<.001). For the fatigue resistance, only polyacetal showed a difference between the initial time-point (P<.05) and subsequent time-points. Polyacetal had a higher fatigue resistance than Teflon (P<.001) and PEEK (P<.05). Regarding the internal deformation of the attachments, a significant difference was observed among the materials (P<.05).

CONCLUSIONS

PEEK showed promising results regarding the physicomechanical properties necessary for use as an overdenture attachment when compared with other evaluated materials. In addition, the PEEK attachment showed results comparable to those in the control group (O-rings) in terms of retention.

A Comparison of Biomechanical Properties of Implant-Retained Overdenture Based on Precision Attachment Type

This paper aims to compare, in vitro, the biomechanical properties of an overdenture retained by two bar-retained implants and an overdenture retained by two bar-retained implants with ball attachments. An edentulous mandible model was prepared for the study based on the FRASACO mold with two implants. In the first system, the “rider” type (PRECI-HORIX, CEKA) retention structure and the complete mandibular denture with the matrix were made. In the second system, the “rider” type retention suprastructure was also used. In the distal part, (CEKA) clips were placed symmetrically, and a complete mandibular denture, together with the matrix on the bar, and the clip patrices were made. A numerical model was developed for each system where all elements were positioned and related to geometric relations, as in reality. The FEA analysis (finite element analysis) was carried out for seven types of loads: with vertical forces of 20, 50, and 100 N and oblique forces of 20 and 50 N acting on individual teeth of the denture, namely central incisor, canine, and first molar. Displacements, stresses, and deformations within the systems were investigated. Maximum denture displacement in the first system was 0.7 mm. Maximum bar stress amounted to 27.528 MPa, and implant stress to 23.16 MPa. Maximum denture displacement in the second system was 0.6 mm. Maximum bar stress amounted to 578.6 MPa, that of clips was 136.99 MPa, and that of implants was 51.418 MPa. Clips cause smaller displacement of the overdenture when it is loaded but generate higher stress within the precision elements and implants compared to a denture retained only by a bar. Regardless of the shape of the precision element, small deformations occur that mainly affect the mucosa and the matrix.

Ball versus Locator® Attachments: A Retrospective Study on Prosthetic Maintenance and Effect on Oral-Health-Related Quality of Life

Locator^® and ball attachments are well-established systems to attach overdentures to two inter-foraminal implants. This study aimed to evaluate differences between the two systems regarding prosthetic maintenance and patients’ oral-health-related quality of life (OHRQoL). Dental records of patients with a mandibular implant-retained overdenture were retrospectively analyzed. Prosthetic maintenance measures involving the denture suprastructure and attachment matrix and patrix were analyzed. Furthermore, the Oral Health Impact Profile-G14 (OHIP-G14) was used to evaluate OHRQoL. Results were analyzed by means of Kaplan–Meier analysis and Student’s t- and log-rank tests. The records of 122 patients were evaluated. Kaplan–Meier survival analysis revealed a significant difference between ball attachments (Group B; n patients = 47) and Locator^® attachments (Group L; n patients = 75) regarding the occurrence of denture fractures (p < 0.001) and events affecting the matrix (p = 0.028) and patrix (p = 0.030). Group L had a significantly lower total OHIP-G14 score than Group B (p = 0.002). The most common maintenance events were matrix-related and denture relining for both attachment systems. Group B required more maintenance measures than Group L. Moreover, patients in Group L had better OHRQoL than patients in Group B.