Abstract
Aim:
To compare the functional, mechanical, biological, and patient-reported outcomes of ball & socket versus locator attachment systems used in implant-assisted cast partial dentures (IACPDs).
Settings and Design:
This randomized clinical study included patients with Kennedy Class I and Class II mandibular arches. A total sample size of 20 patients was determined, and allocation to attachment groups was performed. Cone beam computed tomography (CBCT) was used with a radiographic stent for treatment planning, which was subsequently utilized as a surgical guide for implant placement. Prosthetic rehabilitation was carried out using IACPDs designed with Exocad® software (Darmstadt, Germany).
Materials and Methods:
Following implant placement, patients were rehabilitated with IACPDs incorporating either ball and socket or locator attachments. Outcomes were assessed at a 6-month follow-up. Functional parameters: masticatory efficiency. Mechanical parameters: wear of acrylic teeth, nylon ring wear, framework fracture, and dislodgement of the metal retentive housing. Biological parameters: marginal bone level changes assessed using CBCT and soft-tissue health evaluated using periodontal indices. Patient-reported outcomes: assessed using a structured questionnaire.
Statistical Analysis Used:
All collected data were tabulated and analyzed using SPSS Version 26 (IBM Corporation, Armonk, NY, USA). Independent t-test, Fisher’s exact test, and Mann–Whitney U test were used as appropriate. Statistical significance was set at P < 0.05.
Results:
Nineteen participants completed the study (10 in the ball and socket group and 9 in the locator group), as one participant was lost to follow-up. Functional outcomes: Masticatory efficiency showed a statistically significant improvement in the locator attachment group when analyzed using an independent t-test (P < 0.001). Mechanical outcomes: Mechanical complications assessed using Fisher’s exact test revealed no significant intergroup difference (P = 0.370). Biological outcomes: Marginal bone levels decreased significantly from baseline to follow-up within both groups; however, intergroup comparison using the Mann–Whitney U test showed no statistically significant difference (P = 0.584). Periodontal indices demonstrated a statistically significant difference favoring the locator attachment group.
Conclusion:
Within the limitations of this study, implant-assisted cast partial dentures demonstrated favorable functional, mechanical, biological, and patient-reported outcomes, with locator attachments showing superior performance compared to ball and socket attachments.
Keywords: Ball and socket attachment, implant, implant-assisted cast partial denture, locator attachment, marginal bone loss, masticatory efficiency, mechanical complications, patient-reported outcomes, removable partial denture
INTRODUCTION
The prevalence of partially edentulous arches; Kennedy Class I and II, is increasing with the growing population within the age group of 35–64 years.[1] The treatment modalities used for rehabilitating are removable and fixed prosthesis, depending upon the edentulous span, the morphology and anatomy of the bone and the associated structures.[2] Implant-assisted cast partial dentures (IACPDs) are a reliable means to rehabilitate partially edentulous arches, overcoming the limitations thereby with the conventional rehabilitation methods.[3]
The treatment modality widely uses implants with cast partial dentures to improve retention and stability by strategically placing implants in distal extension cases. IACPD effectively changes the Kennedy Class I and II to a more stable Kennedy Class III, significantly improving the retention, stability and function.[4] This biomechanical modification reduces shear forces and bending movements on the prosthesis and helps to preserve the residual ridge and surrounding structures. In addition, implants placed in the posterior region reduce the inadvertent forces on the mucoperiosteum, thereby reducing the bone resorption.
These benefits make IACPDs a minimally invasive and mechanically efficient treatment that bridges traditional removable partial dentures (RPDs) with fixed implant-supported prostheses.[5,6]
There are many attachment systems used to retain IACPDs, such as ball and socket, locator, magnets, bar and clip, etc. The conventional RPDs were insufficient for distal extension cases (Kennedy Class I and II) as patients frequently complained of poor retention, stability, reduced chewing efficiency and overall patient satisfaction.
Ball and socket attachments are the most commonly ones used, comprising a female nylon cap that is changeable and inserted in the denture base, and a male metal ball and socket that is placed over the implant. Another ones are the locator attachment, which has a low-profile design, dual retention (internal and exterior friction), and self-aligning capabilities. These features can be helpful for patients who have problems with manual dexterity or limited interarch space.
Although each attachment system offers distinct advantages and limitations, current literature provides no definitive evidence favoring one system over another when compared to functional, mechanical, biological and patient-reported outcomes.
In the literature, only a few studies documented the use of attachment systems in IACPDs. Most of the studies are either finite element analysis, in vitro studies or case reports. Till date, there are no studies, which compare ball and socket and locator attachments in IACPDs.[7]
To address this gap, the present study was done to provide a comprehensive in vivo comparison of these two attachment systems, focusing on functional, mechanical, biological, and patient-related outcomes.[8,9]
The null hypothesis affirms that there is no major statistical difference between the ball and socket as well as the locator attachment with respect to functional, mechanical, biological, and patient-related outcomes.
MATERIALS AND METHODS
This study was conducted at the department of prosthodontics and crown and bridge, Subharti Dental College and Hospital, Swami Vivekanand Subharti University, Meerut, Uttar Pradesh, India, following the CONSORT guidelines.
The University Ethics Committee (medical) granted the approval for the study, reference number [SMC/UECM/2023/637/296] on August 23, 2023. This trial was registered under Clinical trial registry of India [CTRI number: CTRI/2024/02/062545].
For this study, 20 patients with Kennedy Class I and Class II mandibular arches were recruited after obtaining written informed consent, and selection was carried out according to the predefined inclusion and exclusion criteria.[10]
Based on the inclusion and exclusion criteria, patients with bilateral or unilateral missing posterior mandibular teeth (Kennedy Class I and Class II) aged between 18 and 75 years, maintaining adequate periodontal and gingival health, adequate interarch space for the prosthetic rehabilitation and have an infection-free implant site were included.
Patients with uncontrolled systemic illnesses (uncontrolled diabetes, recent myocardial infarction, valvular surgery, bleeding disorders, acute renal failure, and immunosuppression), psychiatric conditions, active and uncontrolled periodontal diseases, insufficient interarch space, patients with a history of parafunctional habits, history of local radiation therapy to the orofacial region, and general and medical contraindications for the surgical procedures were all excluded.
Randomization to either ball and socket or locator attachment groups was conducted using a parallel-group design with concealed allocation via sequentially numbered opaque envelopes, opened by anon-study staff member.
A parallel group design was used to randomly assign patients to receive ball and socket attachment (Group 1) and locator attachment (Group 2) before prosthesis planning. A nonstudy staff member successively distributed envelopes with random codes following the preparation of the randomisation lists. Every implant was scheduled using the designated interventions.
The formulated study was a single-blind trial, in which the examiner assessing functional, mechanical, biological, and patient-reported outcomes was blinded to the type of attachment used post training.
Phase I: Preprosthetic phase
Diagnostic impression was made using irreversible hydrocolloid (Plastalgin, Septodont, France) and the models were obtained using dental stone (Type III, Ultrarock, Kalabhai). A diagnostic wax up was done to evaluate the interarch space. A radiographic stent was fabricated for cone beam computed tomography (CBCT) evaluation which was later used as a surgical stent for implant placement.
Phase II: Surgical phase
Utilizing the fabricated stent, implants were placed (regular platform Adin) in posterior mandible. The implants were placed subcrestally with an insertion torque of 35 Ncm. Cover screws were placed and primary closure achieved using resorbable sutures (Ethicon™, Johnson and Johnson Medical N.V.). This was submerged for 3 months, followed by the second stage surgery and the placement of gingival formers.
Phase III: Prosthetic phase
Definitive putty light body (3M ESPE) impressions were made 2 weeks after the second stage surgery, and the master cast was verified using a passive fit jig. The framework was then digitally designed using Exocad® software (Darmstadt, Germany) and fabricated accordingly. A pick-up impression was made, followed by the trial and the prosthesis was delivered to the patient [Figure 1]. The marginal bone loss (MBL), soft tissue evaluation (modified plaque index [MPI], and modified sulcus index [MSI]) and the patient reported outcomes were analyzed at the baseline.
Figure 1.
Clinical steps of implant-assisted cast partial denture fabrication
Phase IV: Postprosthetic phase
After a period of 3 months postprosthetic rehabilitation, functional parameters like the masticatory efficiency were assessed using the mixing ability test[11] [Figure 2], patient were asked to chew two silicone cubes of blue and white colour (30 mm × 18 mm × 3 mm inches) for 20 chewing cycles and then the chewed bolus was analysed for hue score using view gum software. Obtained data for ball and socket attachment and locator attachment was analysed. Thereafter, mechanical complications such as wear of acrylic teeth, nylon ring wear, fracture of cast partial framework, and dislodgment of metal retentive housing were also observed and recorded 3 months post insertion and data collected was statistically analysed. CBCT was used for estimating the MBL, 9 months post implant placement, it also helped evaluating the health of the implant, thus analysing the bone quality and quantity changes, leading to the verification of secondary implant stability. MPI and modified sulcular bleeding index were used to obtain data for plaque accumulation and bleeding tendency, 6 months post insertion of the prosthesis, and further this data was also analysed.
Figure 2.
Assessment of masticatory function
In addition to this, the patient-reported outcomes were also evaluated subjectively, by asking the patient to fill the oral health impact profile (OHIP)-14 questionnaire, prior and post to treatment.
The combined data were tabulated and assessed statistically using independent t-test, Fischer’s exact test and Mann–Whitney test respectively, for intra group evaluation.
The analysis was carried out using SPSS Version 26 IBM Corporation, Armonk, NY, USA.
RESULTS
Twenty patients were enrolled in the study, but one patient was lost to follow-up after implant placement, and hence, data analysis was done on 19 participants. Ten patients were assigned to the ball and socket attachment (Group 1), and the other ten patients were assigned to the locator attachment (Group 2). Follow-up assessment included evaluation of functional (masticatory efficiency), mechanical complications (wear of acrylic teeth, nylon ring, framework fracture and dislodgement of metal retentive housing), biological parameters (MBL, MPI and MSI) and patient-reported outcomes, respectively.
Functional parameters (masticatory efficiency) were assessed using colorimetric analysis with ViewGum software and analyzed using an independent t-test, which revealed a statistically significant difference in the hue scores (P < 0.001) with Group 2 (6.95 ± 0.27) performing better than Group 1 (8.78 ± 0.63), indicating better masticatory function [Table 1].
Table 1.
Comparison of functional parameter (masticatory efficiency) measured using the hue score at 6-month follow-up
| Attachment | Mean±SD | MD | 95% lower | 95% upper | P |
|---|---|---|---|---|---|
| Group 1 | 8.78±0.63 | 1.83 | 1.36 | 2.31 | <0.001* |
| Group 2 | 6.95±0.27 |
*A significant difference at P≤0.05. Independent t-test. SD: Standard deviation, MD: Mean difference
In consideration to mechanical parameters, there were no significant complications when assessed using Fischer’s exact test during the follow-up, but slight acrylic tooth wear was seen more often in Group 2, although not statistically significant. Since there was a time constraint while conducting the study, inconclusive data were obtained [Table 2].
Table 2.
Comparison of mechanical complications at 6-month follow-up
| Mechanical complications | Attachment | Present, n (%) | Absent, n (%) | P |
|---|---|---|---|---|
| Wear of acrylic teeth | Group 1 | 4 (40) | 6 (60) | 0.370 |
| Group 2 | 6 (66.7) | 3 (33.3) | ||
| Wear of nylon ring (loose prosthesis) | Group 1 | 0 | 10 (100) | - |
| Group 2 | 0 | 9 (100) | ||
| Framework fracture | Group 1 | 0 | 10 (100) | - |
| Group 2 | 0 | 9 (100) | ||
| Dislodgment of the metal retentive housing | Group 1 | 0 | 10 (100) | - |
| Group 2 | 0 | 9 (100) |
Fisher’s exact test
With regard to marginal bone levels [Figure 3], both groups when analyzed using the same test presented statistically significant decrease from baseline to 6 months and presented a mean MBL of 0.33 ± 0.22 mm for the Group 1 and 0.29 ± 0.19 mm for Group 2, but the intergroup difference was not statistically significant (P = 0.584) [Table 3].
Figure 3.
Assessment of marginal bone loss
Table 3.
Comparison of marginal bone loss between the two attachment groups at 6-month follow-up
| Attachment | Mean±SD | IQR value | MD | 95% lower | 95% upper | P |
|---|---|---|---|---|---|---|
| Group 1 | 0.33±0.22 | 0.515 | 0.04 | −0.08 | 0.17 | 0.584 |
| Group 2 | 0.29±0.19 | 0.81 |
Mann–Whitney test. SD: Standard deviation, MD: Mean difference, IQR: Interquartile range
In relation to soft tissue indices, MPI increased substantially in both groups between the 6 months (P < 0.001) and comparison identified uniformly higher scores in Group 1 at baseline (P = 0.053) and follow-up (P < 0.001) when analyzed using Mann–Whitney test. Moreover, both attachment groups showed a significant decrease in the MSI in both groups reflecting enhanced peri-implant soft tissue health from baseline (P = 0.060) to 6 months (P < 0.001) when studied using the same test [Table 4].
Table 4.
Comparison of periodontal indices at 6-month follow-up period
| Parameter | Interval | Group | Mean±SD | IQR value | MD | 95% CI (lower-upper) | P |
|---|---|---|---|---|---|---|---|
| MPI | Baseline | Group 1 | 0.64±0.15 | 0.25 | 0.09 | 0.00–0.18 | 0.053 |
| Baseline | Group 2 | 0.55±0.13 | 0.25 | ||||
| 6 months | Group 1 | 1.11±0.24 | 0.375 | 0.29 | 0.15–0.44 | <0.001* | |
| 6 months | Group 2 | 0.82±0.23 | 0.25 | ||||
| MSI | Baseline | Group 1 | 1.73±0.23 | 0.25 | 0.16 | 0.02–0.30 | 0.060 |
| Baseline | Group 2 | 1.57±0.23 | 0.25 | ||||
| 6 months | Group 1 | 1.43±0.26 | 0.25 | 0.41 | 0.28–0.54 | <0.001* | |
| 6 months | Group 2 | 1.02±0.16 | 0.215 |
Mann–Whitney test, *A significant difference at P≤0.05. SD: Standard deviation, MD: Mean difference, IQR: Interquartile range, CI: Confidence interval, MPI: Modified plaque index, MSI: Modified sulcus index
At base line, the patients were evaluated using the OHIP questionnaire and there was no statistically significant difference between both the groups but at follow-up of 6 months, patient reported outcomes were analysed using Mann–Whitney test and the Group 2 showed significantly higher patient satisfaction as evidenced by a lower mean satisfaction score (1.60 ± 0.38) than the Group 1 (1.84 ± 0.30), with the difference being statistically significant (P = 0.035) [Table 5].
Table 5.
Comparison of patient satisfaction (oral health impact profile-14) between the two attachment groups after 6 months
| Question | Group 1 |
Group 2 |
MD | 95% CI |
P | |||
|---|---|---|---|---|---|---|---|---|
| Mean±SD | IQR | Mean±SD | IQR | Lower | Upper | |||
| Q1 | 1.90±0.32 | 0 | 1.44±0.53 | 0 | 0.46 | 0.04 | 0.87 | 0.095 |
| Q2 | 1.90±0.57 | 0 | 1.89±0.60 | 0 | 0.01 | −0.56 | 0.58 | 0.968 |
| Q3 | 2.00±0.82 | 2 | 1.67±0.87 | 1.5 | 0.33 | −0.48 | 1.15 | 0.400 |
| Q4 | 2.00±0.00 | 0 | 1.89±0.60 | 0 | 0.11 | −0.29 | 0.51 | 0.720 |
| Q5 | 2.10±0.74 | 1 | 1.56±0.73 | 1 | 0.54 | −0.17 | 1.26 | 0.156 |
| Q6 | 1.90±0.74 | 1 | 1.44±0.73 | 1 | 0.46 | −0.26 | 1.17 | 0.211 |
| Q7 | 1.90±0.32 | 0 | 2.11±0.33 | 0 | −0.21 | −0.53 | 0.10 | 0.497 |
| Q8 | 1.90±0.57 | 0 | 2.00±0.71 | 0 | −0.10 | −0.72 | 0.52 | 0.780 |
| Q9 | 1.80±0.42 | 0 | 1.44±0.53 | 1 | 0.36 | −0.10 | 0.82 | 0.211 |
| Q10 | 2.00±0.67 | 0 | 1.67±0.71 | 1 | 0.33 | −0.33 | 1.00 | 0.356 |
| Q11 | 1.60±0.52 | 0 | 1.11±0.33 | 0 | 0.49 | 0.06 | 0.92 | 0.079 |
| Q12 | 1.80±0.63 | 1 | 1.33±0.50 | 1 | 0.47 | −0.09 | 1.02 | 0.156 |
| Q13 | 2.00±0.00 | 0 | 1.67±0.50 | 0 | 0.33 | 0.00 | 0.67 | 0.243 |
| Q14 | 1.00±0.00 | 0 | 1.22±0.44 | 0 | −0.22 | −0.52 | 0.07 | 0.447 |
| Total | 1.84±0.30 | 0 | 1.60±0.38 | 0 | 0.24 | −0.09 | 0.57 | 0.035* |
*A significant difference at P≤0.05. Mann–Whitney test. SD: Standard deviation, MD: Mean difference, IQR: Interquartile range, CI: Confidence interval
Group 2 outperformed Group 1 in the functional parameter (masticatory efficiency) (P < 0.001). Mechanical complications were minimal and not statistically significant (P = 0.370). MBL showed no intergroup difference (P = 0.584). Plaque scores were significantly higher in the Group 1 at follow-up (P < 0.001), whereas both groups demonstrated significant improvements in sulcus bleeding indices over time (P < 0.001). In terms of patient reported outcomes, Group 2 gave more satisfactory results (P = 0.035).
DISCUSSION
Conventional RPD used for rehabilitating Kennedy Class I and II arches face significant challenges including alveolar bone resorption, caries in abutment teeth, compromised periodontal health and biomechanical instability from unequal tissue resilience. In bilateral mandibular extensions, limited support and friable mucosa lead to destabilizing forces, saddle displacement and damage to abutments, often resulting in food entrapment, discomfort and patient dissatisfaction, often resulting in discontinuation of prosthesis.[7]
Dental implants offer an effective alternative to conventional RPDs, although accelerated bone resorption can limit placement. In these situations, a modified treatment modality, IACPD, has been proposed which entails a combined use of implants and cast partial dentures.[12] Strategic placement of implants in distal extension ridges reduces stress on the mucoperiosteum and residual ridge, minimizes shear forces, enhances prosthetic stability, and improves overall treatment outcomes.[13] The long-term success of this enhanced modality, however, is influenced by the choice of attachment system – commonly including ball and socket, locator, bar-and-clip and magnetic attachments. Among these, ball and socket and locator attachments are most frequently employed due to their clinical reliability and patient-centred advantages.[14]
Ball and socket attachments exert lower stress on peri-implant bone compared to other systems, while locator attachments, offering dual retention, self-alignment and a low vertical profile becomes ideal for limited interocclusal space. Although each system has distinct benefits, current studies indicate no definitive superiority in clinical outcomes such as masticatory performance, mechanical complications, MBL, plaque accumulation, bleeding tendency, and patient satisfaction.[15,16]
To date, the literature lacks clinical studies directly comparing ball and socket and locator attachments. Studies have reported the absence of evidence comparing these two attachment systems with respect to masticatory function, mechanical complications, and patient-reported outcome measures in mandibular IACPDs.
Functional parameters
Functional performance evaluated through masticatory efficiency revealed a significant difference between the two groups. The hue index, used as an inverse marker of chewing ability,[17] was significantly lower in the locator group (6.95 ± 0.27) compared to the ball and socket group (8.78 ± 0.63) (P < 0.001) indicating superior masticatory function with the locator attachment.
Improvement in functional parameter (masticatory efficiency) with IACPDs has been well documented. Jensen et al.[18] and Bandiaky et al.[19] reported significant functional benefits while Murakami et al.[20] further demonstrated that IACPDs generated higher occlusal forces and superior masticatory efficiency compared with conventional dentures.
Findings from the present investigation are in agreement with these reports, indicating enhanced masticatory efficiency with IACPDs. Among the attachment systems evaluated, locator attachment supported IACPDs exhibited more favourable performance outcomes than ball and socket attachment supported IACPD.
Mechanical parameters
No major mechanical complications were reported in either group during the 6-month follow-up, which was a limited time period to give a conclusive statement. Minor acrylic tooth wear was observed, more frequently in the locator group, although this difference was not statistically significant (P = 0.370). The present results were consistent with existing literature, which has similarly reported minimal mechanical or technical complications in implant assisted RPD, even over prolonged observation periods. For instance, Gupta N et al.[15] in their systematic review observed that utilizing ball and socket attachment, minimum complications were observed. Similar to this, Chiu LP et al.[21] observed that all plastic retentive components (matrixes) needed to be replaced after a year of usage, although they did not find any indication of locator attachments becoming looser. As per this study, both locator and ball and socket supported IACPD showed equivalent outcomes in terms of mechanical complications.
Biological parameters (marginal bone loss, peridontal indices)
Building upon these subjective assessments, the study further examined biological parameters, with MBL serving as the first clinical indicator. According to the implant success criteria established by Albrektsson et al.,[22] a MBL of <1.5 mm during the 1st-year postinsertion, and not exceeding 0.2 mm annually thereafter is deemed acceptable. In the present investigation, the ball and socket attachment group exhibited a mean MBL of 0.52 mm from baseline to the 6-month follow-up. Although this change was statistically significant (P = 0.001), it remained well within the accepted clinical threshold.
Interestingly, among studies evaluating ball and socket attachments, Payne et al.[23] reported the greatest MBL with a mean loss of 2.20 ± 0.81 mm over a 3-year period in mandibular implant assisted RPDs, suggesting a potential for increased crestal bone resorption under specific clinical conditions.
There was a statistically significant mean MBL in the locator attachment group, (MBL) of 0.29 mm (P = 0.001), well within the acceptable thresholds for implant success defined by Albrektsson et al.[22] This aligns with findings by Turkyilmaz and Tözüm[24] who reported comparable MBL values over an 18-month follow-up. Although the locator group demonstrated slightly lower bone loss than the ball and socket group at 6 months, the intergroup difference was not statistically significant. These outcomes suggest both attachment types support acceptable levels of peri-implant bone preservation, although further long-term studies are warranted to elucidate sustained bone behavior.
In addition to radiographic evaluations, periodontal indices reflected meaningful trends. A progressive increase in MPI values observed in both groups over 6 months, reaching statistical significance (P < 0.001) reflected the unavoidable aspect of maintenance of all the attachments. The ball and socket attachment group consistently demonstrated higher MPI scores than the locator group, with the difference attaining statistical significance at the 6-month follow-up (P = 0.053 at baseline; P < 0.001 at 6 months) directing towards the need for more hygiene maintenance with ball and socket attachment. A similar pattern was noted in MSI values, which increased significantly in both groups (P < 0.001), suggesting a rise in soft tissue inflammation across all attachment types. These findings followed a similar trend to the study by Mously et al.[10] where the mean difference in the pocket depth from baseline to the subsequent time intervals was higher in the ball and socket attachment group than the locator group. However, this observation was not statistically significant (P > 0.05). Present study concluded that ball and socket attachment requires more maintenance and soft tissue inflammation than locator attachment.
Patient-reported outcomes
Initial assessments of patient-reported outcomes have demonstrated superior satisfaction with the use of locator attachment systems. This aligns with the findings of Mathew JE et al.,[17] Ibrahim AM et al.[25] Ohkubo et al.,[26] and Mitrani et al.[27] who collectively reported significant increases in patient satisfaction after switching to IACPDs from traditional RPDs.
Statistically significant differences between the two groups were observed for masticatory efficiency, biological parameters and patient-reported outcomes, leading to rejection of the null hypothesis for these measures. Conversely, no significant differences were detected in MBL or mechanical complications, resulting in acceptance of the null hypothesis for these parameters. In parallel with these considerations, the occlusion developed with IACPDs, should be physiologically harmonious, ensuring that functional stresses are evenly distributed across all occluding teeth to maintain the health of supporting structures. In patients with a stable occlusal scheme, it is advisable to preserve existing articulation either mutually protected or group function. Anterior guidance is preferred when natural canines are present, as it minimizes lateral stress on distal extension bases. Conversely, group function may be indicated when canines are absent or compromised; however, in the absence of premolars, this should be avoided, as canine-protected articulation more effectively reduces harmful lateral forces.[28] Anterior most implant placed just adjacent to abutment tooth reduces the harmful stress over it whereas posterior most implant reduces stress over residual ridge.
The limitations of this study were the short duration of follow-up. Limited availability of long-term clinical evidence for these attachment systems has restricted their routine implementation in daily practice. Furthermore, the study is single-centre, with a small and specific patient population (Indian patients, Kennedy I/II) and therefore, the results may not generalize to other settings or arch situations.
Consequently, there is a need for well-structured prospective studies with larger sample populations and extended follow-up periods to thoroughly investigate mechanical, patient-reported and biological outcomes, and to establish more definitive conclusions regarding the comparative effectiveness of these attachment systems in terms of wear and long-term behaviour. Due to the gap in the literature, there is a need for targeted research on occlusal schemes and occlusal relationships to maximize load distribution, increase prosthesis survival, and achieve patient comfort.
CONCLUSION
Given the limits of this study, it’s possible to say that implant-assisted cast partial dentures with locator attachments showed better results than those with ball and socket attachments. Considering functional efficiency, mechanical stability, biological compatibility, and patient satisfaction, locator attachments proved to be superior in all these aspects.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
REFERENCES
- 1.Prasad S, Garg S. Prevalence of partial edentulism and awareness to restore the same among the patients visiting a tertiary dental care centre in Ambala, Haryana, India: A cross-sectional study. J Clin Diagn Res. 2025;19:ZC13–7. [Google Scholar]
- 2.James A, Janakiram C, Meghana RV, Kumar VS, Sagarkar AR, Yuvraj BY. Impact of oral conditions on oral health-related quality of life among Indians: a systematic review and meta-analysis. Health Qual Life Outcomes. 2023;21:102. doi: 10.1186/s12955-023-02170-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Azmi A, Patel I, Solanki K, Patel S, Patel B, Alam J. Prevalence of partial edentulism and its relation to age and gender in Ahmedabad population. J Prosthodont Dent. 2020;15:9–17. [Google Scholar]
- 4.De Leon Flores MA, Nakagoshi Cepeda MAA, Vazquez Sanchez ME, Arias Gomez RE, Del Muro Casas F, Rodriguez Guajardo NA, et al. Implant-assisted removable partial dentures as treatment for Kennedy Class I and II arches: a literature review. Int J Appl Dent Sci. 2024;10:44–8. [Google Scholar]
- 5.Kuroshima S, Ohta Y, Uto Y, Al-Omari FA, Sasaki M, Sawase T. Implant-assisted removable partial dentures: Part I. a scoping review of clinical applications. J Prosthodont Res. 2024;68:20–39. doi: 10.2186/jpr.JPR_D_22_00252. [DOI] [PubMed] [Google Scholar]
- 6.Wang HL, Al-Shammari K. Efficacy of bone grafting versus mini-implants for removable partial denture support. Clin Oral Implants Res. 2017;28:924–31. [Google Scholar]
- 7.Chikunov I, Hyun J. Partial implant-retained overdentures – A treatment option. J Prosthodont. 2009;18:448–54. [Google Scholar]
- 8.Putra Wigianto AY, Goto T, Iwawaki Y, Ishida Y, Watanabe M, Ichikawa T. Treatment outcomes of implant-assisted removable partial denture with distal extension based on the Kennedy classification and attachment type: A systematic review. Int J Implant Dent. 2021;7:111. doi: 10.1186/s40729-021-00394-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Ramchandran A, Agrawal KK, Chand P, Ramashanker, Singh RD, Gupta A. Implant-assisted removable partial denture: an approach to switch Kennedy Class I to Kennedy Class III. J Indian Prosthodont Soc. 2016;16:408–11. doi: 10.4103/0972-4052.179262. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Mously HA. Effect of two implant-supported partial overdenture attachment design on the periodontal health. J Contemp Dent Practice. 2017;21:68–72. [PubMed] [Google Scholar]
- 11.Schimmel M, Christou P, Herrmann FR, Müller F. A two-colour chewing gum test for masticatory efficiency: Development of different assessment methods. J Oral Rehabil. 2007;34:671–8. doi: 10.1111/j.1365-2842.2007.01773.x. [DOI] [PubMed] [Google Scholar]
- 12.Gates WD, 3rd, Cooper LF, Sanders AE, Reside GJ, De Kok IJ. The effect of implant-supported removable partial dentures on oral health quality of life. Clin Oral Implants Res. 2014;25:207–13. doi: 10.1111/clr.12085. [DOI] [PubMed] [Google Scholar]
- 13.Gaur T, Goswami R, Mowar A, Sharma D, Gupta P, Sharma A, et al. Marginal bone level measurements of unsplinted implants used for mandibular overdentures: A six-month randomized prospective clinical study comparing early and delayed loading protocols. Cureus. 2023;15:e35210. doi: 10.7759/cureus.35210. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Ghotmi M, Homsy F, Daou E. The Locator: a useful attachment for overdentures. A practical description. J Lebanese Dent Assoc. 2013;48:69–74. [Google Scholar]
- 15.Gupta N, Bansal R, Shukla NK. The effect of ball versus locator attachment system on performance of implant supported overdenture: A systematic review. Journal of Oral Biology and Craniofacial Research. 2023;13:44–5. doi: 10.1016/j.jobcr.2022.11.001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Varshney N, Kusum CK, Trivedi A, Kaushik M, Dubey P, Bali Y. Comparative evaluation of biological, mechanical, and patient-reported outcomes of angulated screw channel abutments versus multi-unit abutment-retained single-unit implant restorations in the anterior esthetic zone: An-in vivo study. J Indian Prosthodont Soc. 2023;23:244–52. doi: 10.4103/jips.jips_101_23. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Mathew JE, Kurian N, Gandhi N, Daniel AY, Roy N, Varghese KG. Comparative evaluation of masticatory efficiency, clinical performance, and patient satisfaction of single implant-retained mandibular overdenture versus conventional complete denture: A prospective in vivo study. J Indian Prosthodont Soc. 2024;24:61–8. doi: 10.4103/jips.jips_393_23. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Jensen C, Speksnijder CM, Raghoebar GM, Kerdijk W, Meijer HJ, Cune MS. Implant-supported mandibular removable partial dentures: Functional, clinical and radiographical parameters in relation to implant position. Clin Implant Dent Relat Res. 2017;19:432–9. doi: 10.1111/cid.12484. [DOI] [PubMed] [Google Scholar]
- 19.Bandiaky ON, Lokossou DL, Soueidan A, Le Bars P, Gueye M, Mbodj EB, et al. Implant-supported removable partial dentures compared to conventional dentures: A systematic review and meta-analysis of quality of life, patient satisfaction, and biomechanical complications. Clin Exp Dent Res. 2022;8:294–312. doi: 10.1002/cre2.521. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Murakami K, Ayukawa Y, Ogino Y, Nakagawa A, Horikawa T, Yamaguchi E, et al. Clinical effectiveness of implant support for distal extension removable partial dentures: Functional evaluation using occlusal force measurement and masticatory efficiency. Int J Implant Dent. 2021;7:101. doi: 10.1186/s40729-021-00381-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Chiu LP, Vitale ND, Petridis H, Mc Donald The effect of different water temperatures on retention loss and material degradation of locator attachments. 2017;26:537–44. doi: 10.1111/jopr.12440. [DOI] [PubMed] [Google Scholar]
- 22.Albrektsson T, Zarb G, Worthington P, Eriksson AR. The long-term efficacy of currently used dental implants: A review and proposed criteria of success. Int J Oral Maxillofac Implants. 1986;1:11–25. [PubMed] [Google Scholar]
- 23.Payne AG, Tawse-Smith A, Wismeijer D, De Silva RK, Ma S. Multicentre prospective evaluation of implant-assisted mandibular removable partial dentures: Surgical and prosthodontic outcomes. Clin Oral Implants Res. 2017;28:116–25. doi: 10.1111/clr.12769. [DOI] [PubMed] [Google Scholar]
- 24.Turkyilmaz I, Tözüm TF. Implant-assisted removable partial denture with distal extension: A clinical report. J Prosthodont. 2011;20:311–4. [Google Scholar]
- 25.Ibrahim AM, Alokda MM, Elgamal M. Patient satisfaction, oral health-related quality of life, and masticatory efficiency of bar-retained implant-supported mandibular overdentures with reduced denture base extensions. J Contemp Dent Pract. 2025;26:988–95. doi: 10.5005/jp-journals-10024-3958. [DOI] [PubMed] [Google Scholar]
- 26.Ohkubo C, Kobayashi M, Suzuki Y, Hosoi T. Effect of implant support on distal-extension removable partial dentures: In vivo assessment. Int J Oral Maxillofac Implants. 2008;23:1095–101. [PubMed] [Google Scholar]
- 27.Mitrani R, Brudvik JS, Phillips KM. Posterior implants for distal extension removable prostheses: A retrospective study. Int J Periodontics Restorative Dent. 2003;23:353–9. [PubMed] [Google Scholar]
- 28.Goodacre CJ, Goodacre BJ. What occlusal scheme should be used with removable partial dentures? J Prosthodont. 2021;30:78–83. doi: 10.1111/jopr.13313. [DOI] [PubMed] [Google Scholar]