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Types of nylon inserts: (A) conventional Locator extra-light retention (Le); (B) conventional Locator light retention (Ll); (C) conventional Locator medium retention (Lm); (D) extended range Locator medium retention (Lem); and (E) extended range Locator extra-light retention (Lee).
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Purpose:
To evaluate the effect of distal implant inclination on axial and nonaxial retentive forces of different Locator attachments used to retain mandibular overdentures.
Materials and methods:
Four duplicate mandibular edentulous acrylic models received 2 implants in the canine areas with 0°, 5°, 10°, and 20° distal inclinations. Experimenta...
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Background/Aim: The purpose of this in vitro study was to evaluate the effect of mechanical and chemical denture cleansing methods on dental attachments of varying retention with a scanning electron microscope. Material and Methods: An implant analog and a male part of a dental attachment were embedded into an acrylic block, and an abutment was scr...
Citations
... A recent study by Yilmaz et al. could not find consistent effects despite using a stringent study design [10]. A greater number of publications claim that implant angulation leads to a lower retention force [11,12] of attachments as compared with parallelized situations [13]. From a long-term perspective, a significant decrease in retention seems to be inevitable, but this also occurs earlier when attachments are supported by non-parallel implants [14]. ...
... [10]. A greater number of publications claim that implant angulation leads to a lower retention force [11,12] of attachments as compared with parallelized situations [13]. From a long-term perspective, a significant decrease in retention seems to be inevitable, but this also occurs earlier when attachments are supported by non-parallel implants [14]. ...
... However, retention has to be realized and maintained by matching attachment surfaces, which are approximately 23% smaller as compared with locators. It can only be speculated how much effect the smaller component size would have on longevity, which is affected by several factors, including [18] tooth brushing [19], implant angulation [12,13], as well as the material of the female component [6]. From a technical point of view, smaller components are advantageous as the removable restorations become less bulky and less prone ...
Several factors determine the retention force in removable implant-retained overdentures using prefabricated ball- or locator-type attachment systems. In this context, it was the goal of this in vitro study to examine the effect of implant angulation and female part alignment. Two model situations with two parallel or 12° tilted implants were fabricated onto which locator or ball attachments could be mounted. Simulated prostheses (n = 5) were made as antagonist parts and the assemblies were positioned in a universal testing machine for repeatedly (three times per female attachment) quantifying retention force. Statistical analysis was based on Shapiro–Wilk tests, Levene tests, ANOVAs, Tukey’s HSD tests and Welch t-tests, with the level of significance set at p < 0.05. With tilted implants, the retention force of locators was significantly diminished (p < 0.004) by at least 21%, while with ball attachments, a maximum reduction of 8% was noted, with only yellow inserts showing a significant difference (p = 0.040) compared with the parallel situation. Not aligning female retentive components on tilted implants for achieving a common path of insertion in ball anchors had only a minor effect on retentive force (6.5% increase as compared with aligned female parts), which was not statistically significant (p = 0.100). Not being able to establish a common path of insertion in locator attachments affects retention force. Ball anchors allow for aligning female retentive components, but due to the spherical structure of the male component this seems not even to be necessary.
... Initial retention forces were significantly greater than at the subsequent study intervals, consistent with the findings of previous studies. 15,[28][29][30][31] By the end of 7,200 cycles simulating a 5-year period (four per day), mean retention was significantly reduced in all study groups (p = 0.024) with the LB group exhibiting the highest (108.64 N) and BL group exhibiting the least (37.68 N) retention but all in acceptable range for clinical use as per earlier studies. ...
... Higher retention values than previous studies 15, [28][29][30][31] can be explained on account of differences in the test setup, testing equipment, implant attachment system, clear nylon housing with using different combinations of ball and locator attachment caused significant loss in retention during 1st year and thereafter. The limitation of this study was that the overdenture dislodgement pattern could not completely replicate movements during masticatory function, insertion-removal path, and oral habits of the patients. ...
... 20 On the other hand, Locator attachments can be used with individual implant inclination up to 20 degrees and have a reduced vertical profile. 21,22 Additionally, Locators are self-aligning, resilient, and have double retention inserts 23 with different retention forces. 24 However, it should be noted that locator attachments are subjected to increased wear and loss of retention. ...
... 24 However, it should be noted that locator attachments are subjected to increased wear and loss of retention. 25 In addition, with implant inclination greater than 20 degrees, the use of the straight Locator abutment can subject the implants to increased stresses 21 and accelerate the wear of male nylon components. 22 Using angled abutments for the Locator attachments has several advantages such as correction of implant inclination, achieving a common path of insertion for the prosthesis that is perpendicular to the occlusal plane, and enhancing esthetics by minimizing the thickness of the denture base around the buccally angled straight abutments. ...
Objectives
This study aimed to evaluate the clinical outcomes and patient satisfaction of 4‐implant‐assisted maxillary overdentures using two different designs.
Materials and Methods
Thirty edentulous participants received four implants in the maxillary ridge. The patients were randomly divided into two equal groups: (1) the control (CG, Vertical) group ( n = 15); participants received four vertical implants with straight locator attachments to retain maxillary overdentures, and (2) the study (SG, Angled) group ( n = 15); participants received four angled implants with angled locator attachments to retain maxillary overdentures. Peri‐implant tissue health [Plaque (PL) and gingival (GI) indices, pocket depth (PD), implant stability (ISQ) and crestal bone loss (CBL)] were evaluated after denture insertion (T0), 6 (T6), and 12 (T12) months after insertion. Patient satisfaction was evaluated using a visual analog scale (VAS) after 12 months.
Results
The survival rates were 96.7% and 95% for the control and study groups respectively. PL, GI, and PD increased significantly in both groups with the passage of time. No significant difference in PL, GI, PD, and ISQ was noted between groups at all observation times. CG showed higher CBL than SG at T12. For the VAS results, there was no significant difference between groups. SG recorded significantly higher satisfaction regarding comfort with maxillary and mandibular dentures, retention of mandibular dentures, oral hygiene, the ability to chew hard food, and occlusion than CG.
Conclusion
Within the limitations of this study, angled implants with angled locator attachments may be recommended to retain maxillary overdentures opposing intact dentition or fixed restoration as it was associated with improvements of several parameters of peri‐implant tissue health and patient satisfaction compared to vertical implants with straight locator attachments.
... Edentulous jaws can be restored using implant-retained removable dental prostheses, and this treatment is associated with both high success and patient satisfaction (Mahanna et al., 2020). The restoration can be simple, with one or two implants supporting ball attachments, parallel wall attachments (Locator) or joint bars, or advanced, with 4-8 implant-supporting bars, fixed dental prostheses or single crowns (Elsyad et al., 2019;Friberg & Jemt, 2010;Kern et al., 2019;Ma et al., 2010;Matthys et al., 2019;Walton et al., 2009). Many studies have shown that restoration with two implants is effective and has high survival rates (Bakker et al., 2019;Mahgoli et al., 2019). ...
Aim:
To evaluate the long-term survival, incidence of prosthetic/technical and biological complications and the oral-health-related quality of life in patients with an edentulous mandible who were fitted with overdentures on two immediately loaded implants in the symphyseal area.
Materials and methods:
Forty-six patients with edentulous mandibles received two immediately loaded implant-retained dentures with either two Locator attachments or egg-shaped bar attachments. Implant outcomes were recorded after a period of observation of 9 years and included prosthetic complications, modified gingiva index (mGI), modified plaque index (mPI), oral health impact profile (OHIP-G) and radiographic estimation of bone loss.
Results:
In 2020/2021, 27 patients with 54 implants were still available for follow-up. In total, nine implants in six patients were lost. Survival was 89.1% in the bar group and 91.3% in the Locator group. Implant success was 84.6% in the Locator group and 76.9% in the bar group. The mPI values were significantly higher in the bar group than in the Locator group, whereas no difference was seen in the mGI values. During the observation period, 152 prosthetic complications occurred, but the OHIP-G score did not differ significantly.
Conclusions:
There was no difference in implant survival between Locator or joint bar attachments over a 9-year observation period. Joint bar attachments were associated with slightly more complications, while patients in the Locator group were able to maintain better oral hygiene. The study was registered in the German Register of Clinical (Trials DRKS00004245).
... 12,16 Denture retention is defined as the maximum force developed along the insertion direction of the denture until dislodgment from its mucosal and or implantbearing surfaces. 10,16,18 To ensure a satisfactory retention level, some authors suggested that 5-7 N are sufficient for IRMOs 6,12,19 but without specifying the number of implants, whereas other investigators proposed 10 N 20 or 20 N for 2-IRMOs. 21,22 Usually, greater retention leads to greater patient satisfaction. ...
... 9 Because of the spherical shape of the abutment, BAS are minimally affected by interimplant angulation, the friction surfaces between male and female parts being identical for low angles (<30 • ). 9,13 For CAS, in vitro studies have confirmed that interimplant angulation significantly affects its initial retention 8,10,16,18,25 even if no clear tendency between angulation and retention could be highlighted because of the complexity of the interactions between male and female parts. Angulation of the AS should be carefully controlled to limit this bias. ...
... Retention was only measured along the chosen insertion axis, with a selected speed that does not represent the actual in vivo non-axial dislodging loading to which the denture base can be subjected. 18 Lastly, dislodgment tests were conducted in a dry environ-F I G U R E 4 Comparison of the initial retention of the different retention devices inside of each attachment system. The difference is significant between all the Locator® RD; between all the Novaloc® RD (except between NK and NB); between B low and B max positions of the Ball System. ...
Purpose:
To evaluate and compare the initial retention force of three resilient unsplinted attachment systems for implant-retained mandibular overdentures: two cylindrical attachment systems (Locator R-Tx® and Novaloc®), and one ball attachment system (Ball System).
Materials:
and methods. For each attachment system, initial retention is measured as the average of the maximal dislodging forces during 10 insertion-removal cycles. For the Ball System, 3 activation degrees of the matrix are included whereas 4 and 6 color-coded retention devices for the Locator R-Tx® and the Novaloc®, respectively, represent the complete regular retention devices panel. For each retention device or activation degree, 8 samples are tested.
Results:
The initial retention range is similar between the Ball System (7.7 ±3.4 N - 19.9 ±4.6 N) and the Novaloc® (2.0 ±0.5 N - 18.9 ±1.4 N) and broader for the Locator R-Tx® (3.3 ±5.0 N - 60.2 ±6.0 N). In each attachment system, the initial retention of each retention device is significantly different from the others, except for the two most retentive Novaloc® ones. Retention devices were also classified according to their initial retention (low, medium, and maximum). In each retention group, the Novaloc® and the Ball System provided similar retention values lower than the Locator R-Tx®.
Conclusion:
Most of the retention devices tested provided an initial retention force of over 5 N for all three attachment systems. The Locator R-Tx® had the most comprehensive range, and the Novaloc® seemed to provide the most reproducible values, unlike the Ball System due to the activation required by the operator. This article is protected by copyright. All rights reserved.
... 6,13 Resilient studs are advantageous in patients with minimal interarch space, as they limit denture fracture 14 and can be used to compensate implant angulations. 15,16 Studs also have reduced incidence of complications and maintenance compared with other solitary attachments. 17 Patient-centered outcome is very important in evaluating the prosthetic treatment. ...
A common challenge in management of edentulous patients is the atrophied (resorbed) mandibular alveolar ridge. 1 This situation results in construction of dentures with reduced retention and stability, diminished oral function, and psychosocial problems. 2,3 Two-implant-retained mandibular overdentures are considered the minimum prosthodontic care that should be sufficient for most edentulous patients. 4 Such prosthesis provides significant improvement in stability, retention, and patient satisfaction compared with conventional complete dentures. 2 In management of atrophied ridges, two implants stabilizing a mandibular overdenture is an attractive treatment option because of the relatively simple surgical Purpose: The aim of this crossover study was to evaluate patient satisfaction and oral health related-quality of life (OHRQoL) with different connectors used for implant-retained overdentures in subjects with resorbed mandibles. Materials and Methods: Eighteen edentulous patients with atrophied mandibular bone received traditional maxillary and mandibular dentures (control). After 3 months, two implants were inserted in the canine regions. Three months later, each patient received the following overdentures using a crossover design: (1) bar overdentures, (2) telescopic overdentures, and (3) stud overdentures. Patient satisfaction (primary outcome) was measured by visual analog scale (VAS). OHRQoL (secondary outcome) was measured by oral health impact profile (OHIP-14). Questions of VAS and OHIP-14 were evaluated after 3 months of using conventional dentures, bar overdentures, telescopic overdentures, and stud overdentures. Results: For all questionnaires, conventional dentures recorded significantly lower satisfaction than implant overdentures. Stud overdentures showed significantly higher satisfaction with maxillary denture comfort, self-consciousness, and feeling that the prosthesis is a part of the patient compared with other attachments. Bar and telescopic overdentures showed higher satisfaction during biting of hard and soft foods, while telescopic and stud overdentures showed higher satisfaction with oral hygiene. No significant differences between attachments regarding other VAS and OHIP-14 questions were noted. Conclusion: Implant overdentures for subjects with mandibular bone resorption improved patient satisfaction and OHRQoL compared with traditional dentures regardless of the form of attachments. However, studs are more advantageous in term of comfort with maxillary overdentures, self-consciousness, and feeling that the prosthesis is a part of the patient. Bar and telescopic attachments had more satisfaction during biting of soft and hard foods, while telescopic and stud attachments had more satisfaction with oral hygiene. Int J Oral MaxIllOfac IMplants
... Retention forces were evaluated using a previously constructed square metal plate that had five metal chains, attached at each corner and the center. 20,35,[37][38][39][40][41][42] The four corner chains were connected to the four metal hooks of the overdentures, and the main central chain was connected to the head of the universal testing machine (Lloyd). The length of the chains was adjusted by four metal screws attached to the plate to avoid chain slackness. ...
... The maximum peak to dislodgment force in Newtons (N) was calculated as the axial retention force. 20,35,[37][38][39][40][41][42] ...
... To simulate 6 months of overdenture use, each overdenture was inserted and removed 540 times. 20,35,[37][38][39][40][41][42] Another five measurements were then made, and the mean was used as the retention forces after wear simulation. ...
Purpose:
To compare the axial and nonaxial retention forces of different milled bar attachment designs for maxillary implant overdentures.
Materials and methods:
Four implants were placed in the canine and second premolar areas of an edentulous maxillary ridge model and connected to a cobalt-chromium milled bar either with or without Locator attachments. According to the type of bar and overlying housing, the following groups (n = 10 each) were investigated: group 1 (MWM) = milled bar without attachments and metal housing; group 2 (MWP) = milled bar without attachments and PEEK housing; group 3 (MAM) = milled bar with Locator attachments and metal housing; and group 4 (MAP) = milled bar with Locator attachments and PEEK housing. Axial and nonaxial (anterior, posterior, and lateral) retention forces were measured both at baseline and after wear simulation, then compared between groups and dislodging directions.
Results:
MAM showed the highest axial (53.20 ± 2.28 N) and nonaxial (anterior [33.80 ± 1.48 N], posterior [37.60 ± 2.07 N], and lateral [34.40 ± 1.67 N]) retention forces at baseline, followed by MAP, then MWM, and MWP (P < .001). MAP showed the highest axial (42.80 ± 2.28 N) and nonaxial (anterior [24.00 ± 1.58 N], posterior [29.40 ± 2.07 N], and lateral [27.80 ± 1.64 N]) retention forces after wear simulation, followed by MAM, then MWP, and finally MWM (P < .001). MAM showed the highest axial (25.25 ± 2.45 N) and nonaxial (anterior [28.29 ± 4.03 N], posterior [24.40 ± 3.25 N], and lateral [25.55 ± 1.65 N]) retention loss, followed by MWM, then MAP, and finally MWP (P < .001). For all groups, the highest retention forces were noted with axial dislodging, followed by posterior dislodging, then lateral dislodging, and finally vertical dislodging (P < .001).
Conclusion:
Milled bars with PEEK housings and Locator attachments for maxillary implant overdentures were associated with the highest axial and nonaxial retention forces after wear simulation, while milled bars with metal housing and no attachments showed the lowest forces. Milled bars with metal housing and attachments showed the highest retention loss, while milled bars with PEEK housing with no attachments showed retention gain.
... e researchers have found out the differences in the retentive strengths of these attachments by changing implant positions [5], heights [6], and angulations [7][8][9][10]. ...
... Two implants were inserted at the canine areas with 0, 10, 20, and 30 degrees of labial inclination in 4 identical overdenture models using regular retentive inserts and it was found out that the inclination of 30°recorded the highest retention, and the inclination of 20°showed the lowest retention. Elsyad et al. [9] also evaluated the effect of distal implant inclination on dislodging forces of different LOCATOR attachments on 4 similar models with 2 implants placed in the canine region at 0, 5, 10, and 20 degrees of distal inclinations. Axial and nonaxial (anterior, posterior, and lateral) retentive forces were measured initially and after 540 cycles of denture insertion and removal. ...
... Many investors evaluated the effect of cyclic loading on stud attachment wear [9,[11][12][13][14][15] and initial retention was significantly higher than retention after wear or simulated clinical function under different number of insertion-removal cycles for different type of inserts. However, the literature lacks the information on the retentive strength of the attachments without insertion-removal cycles which simulates the overdenture usage from the first day. ...
Objectives:
To evaluate the retentive strength of overdenture attachments in 2-implant mandibular overdenture (2IMO) with implants placed at different positions and angulations.
Materials and methods:
Edentulous mandibular models were 3D-printed using CBCT images and Materialise Mimics software and the denture models using the intraoral scanner. Two standard implants were placed parallel at different positions from midline (5, 10, 15, and 20 mm) with 0-0 degree angulations and with different distal angulations (0-5, 0-10, 0-15, 5-5, 10-10, and 15-15 degrees) at 10±mm from midline representing 10 study groups. Low-profile male attachments were attached to the implants and the female pink attachments were picked up in the denture. A total of 4 simulated overdenture model sets for each of the 10 study groups were subjected to the universal testing machine thrice to measure a peak load (N) to disengage the attachments vertically. Data were analyzed using one-way ANOVA and Tukey's post hoc test at 0.05 significance level.
Results:
Varying implant positions had a statistically significant effect on the retentive strengths of the attachments (F = 5.61, P = 0.002). Peak load-to-dislodgement values (in increasing order) were 49.64 ± 8.27 N for 5 mm, 53.26 ± 11.48 N for 10 mm, 60.24 ± 12.31 N for 15 mm, and 64.80 ± 6.78 N for 20 mm groups. The retentive strength of the 20 mm group was significantly higher than 5 mm (P = 0.003) and 10 mm (P = 0.03) groups. Varying implant angulations had a significant effect on the retentive strengths of the attachments (F = 7.412, P = 0.000). The peak load-to-dislodgement values (in increasing order) were 48.20 ± 15.59 N for 5-5 degrees, 53.26 ± 11.48 N for 0-0 degrees, 54.96 ± 8.25 N for 0-5 degrees, 57.71 ± 7.62 N for 10-10 degrees, 66.00 ± 17.54 N for 15-15 degrees, 66.18 ± 14.09 N for 0-10 degrees, and 77.38 ± 10.33 N for 0-15 degrees. Retentive strength of 0-15 degrees was significantly (P < 0.05) higher than those of 0-0, 0-5, 5-5, and 10-10 degrees and that of 5-5 degrees was significantly (P < 0.05) lower than those of 0-10, 0-15, and 15-15 groups.
Conclusions:
Retentive strength of the 2IMO increased with increase in distance of implants from midline and increased with increase in distal angulations.
... A ppropriate oral function of implant-supported prostheses depends greatly on the stability of the prosthesis. 1 Components such as retentive elements that are used to attach a prosthesis to the implants are prone to degradation and wear during normal use. 2 If these components loosen, proper oral function can be compromised, and both the prosthesis and implants can be subjected to improper stresses that may lead to failure. 1,3 Overdentures have many beneficial features in comparison to complete dentures, as demonstrated by studies evaluating masticatory ability, patient satisfaction, and cost-effectiveness. ...
... 2 Locators (Zest Dental Solutions) are a popular type of stud attachment with dual retention and the capability of self-alignment. 2 Because of their low profile, these attachments are beneficial when the vertical space is limited. 2,4 In addition, Locator attachments can tolerate interimplant angulations ranging from 0° to 20° and strengths of 0 to 5 lb (0 to 2.27 kg). 2 However, these attachments are prone to wear and loss of retention over time. ...
... 2 Because of their low profile, these attachments are beneficial when the vertical space is limited. 2,4 In addition, Locator attachments can tolerate interimplant angulations ranging from 0° to 20° and strengths of 0 to 5 lb (0 to 2.27 kg). 2 However, these attachments are prone to wear and loss of retention over time. 2,3 Attachments may also be replaced based on patients' level of dissatisfaction with their prosthesis. ...
Progressive wear of the components of an implant-supported overdenture can lead to loss of denture retention, which affects masticatory function and the patient's quality of life. The primary objective of this in vitro study was to investigate frictional wear in a type of commonly used abutment and thereby estimate the general clinical lifespan of a typical stud abutment and establish a protocol for replacement. Therefore, simulated overdenture insertions and removals equivalent to 2 years of overdenture use were performed to evaluate surface changes in the metal stud abutment component. A digital caliper, scanning electron micrographs taken at ×500 magnification, and profilometer data were used to determine the wear rate and surface roughness. A universal testing machine was used to measure retention load force with 4 clear male nylon inserts (5.0-lb retention) during 2160 insertion and removal cycles. The results showed that with a 6-month replacement program for clear male nylon inserts, the frictional wear on the titanium nitride coating of abutments placed at a 0° position resulted in a decrease of up to 50% in removal forces of the inserts after a simulated 2 years of wear. The combination of wear of the titanium nitride coating and the decrease in retention load values suggests that stud abutments should be replaced after 2 years of use for optimal retention.
... In addition, Locators have dual retention, different retentive values, and rotational pivoting action. [16][17][18] Reviewing the literature, there is a lack of studies evaluating the difference between maxillary conventional dentures and implant overdentures opposed by mandibular implant overdentures. In addition, the condition of mandibular teeth was not standardized. ...
... 46 The negative influence of implant inclination on the retention of Locator attachments was demonstrated in several in vitro studies. 18,47,48 A similar observation was noted in another study 19 in which the authors reported that the most frequent complications of maxillary OD opposed by implant-supported mandibular overdentures or partial dentures were loss/replacement of the nylon caps and denture relining. They also reported a low incidence of abutment screw loosening and prosthetic tooth fracture. ...
Purpose:
To evaluate patient satisfaction and prosthetic complications of maxillary conventional dentures and implant overdentures opposing mandibular implant overdentures with different attachments.
Materials and methods:
A total of 60 patients with maxillary conventional dentures (maxillary CD) and mandibular two-implant overdentures received four implants in the maxilla. The implants were connected to the maxillary overdentures with a stud attachment (maxillary OD). The participants were classified into three groups according to the type of mandibular overdenture attachment: bar overdentures (BOD, n = 20), resilient telescopic overdentures (TOD, n = 20), and resilient stud/Locator overdentures (LOD, n = 20). Patient satisfaction (using a visual analog scale [VAS] and oral health-related quality of life (OHRQoL)] and prosthetic/soft tissue complications were evaluated for maxillary CD and maxillary OD after 1 year of insertion.
Results:
LOD showed higher VAS and oral health impact profile (OHIP-14) scores with maxillary CD and maxillary OD than BOD and TOD except for ease of chewing (VAS) and satisfactory diet (OHIP-7). For maxillary CD, TOD showed a significantly higher frequency of prosthetic and soft tissue complications than BOD and LOD. For all groups, maxillary OD showed significantly higher patient satisfaction regarding VAS and OHIP-14 scores, and lower prosthetic and soft tissue complications than the maxillary CD.
Conclusion:
Locator-retained maxillary overdentures opposing mandibular implant overdentures improved patient satisfaction and reduced prosthetic complications compared to conventional maxillary dentures. Such overdentures are best opposed by Locator-retained mandibular overdentures, as they increase patient satisfaction and reduce prosthetic and soft tissue complications compared to the bar and telescopic attachments.
