Residual ridge and peri-implant outcomes in mandibular overdentures retained by four Locator versus four bar attachments: a 10-year retrospective analysis.

Effect of implant number, attachment type, and framework material on stress distribution in mandibular overdentures: a finite element analysis

To record Implant stability and marginal bone height changes for Submerged and Non submerged protocol for the Single Implant Retained Mandibular Overdenture (SIMRO). A single symphseal implant was installed in a completely edentulous mandible. At implant placement, the Implant Stability Quotient (ISQ) was recorded using the Osstell device. Using sealed envelopes, patients were randomized into Non-submerged (NS) and Submerged (S). After 3 month, implant stability for both groups was recorded using Osstell device (ISQ). The periotest device was used to follow up implant stability (PTV), and marginal bone height changes were recorded at pick up and after 12 month. Comparison of ISQ within groups was done using the Paired t-test. The Mann- Whitney U test for two independent groups was used to compare between marginal bone height changes and PTV. P values less than 0.05 was considered statistically significant. A significant decrease in the ISQ values for both groups was observed, NS showed a statistically significant higher ISQ value (74.89±3.473) than S (71.53±6.122) (P=0.017) after 3 month. Marginal bone height changes and PTV didn't show any significant difference but were in favor for NS protocol. Both healing protocols showed physiologically acceptable implant stability and marginal bone height changes after 12 month. The Non submerged protocol improved stability with minimum marginal bone height changes for SIMRO.

To evaluate the retention of implant retained mandibular overdenture with polyether-ether-ketone (PEEK) bar using either ready-made nylon clips or custom-made PEEK clips over a one-year randomized clinical study. Twenty completely edentulous patients received two implants inserted bilaterally in the canine-premolar region. A milled PEEK bar was screwed to the multiunit abutment screwed to the implants. Patients were divided equally into two groups (n = 10) according to clip material; group1: ready-made nylon clip and group 2; PEEK clip (Pressed BioHPP®). Clips were picked up into the fitting surface of the overdenture. Retention force was measured at insertion, three months, six months and one year using universal testing machine. Data were analysed using two-way repeated measure ANOVA followed by Bonferroni post-hoc tests (p ≤ 0.5). Retention values between nylon clip group and PEEK group revealed non-statistically significant difference at insertion (28.98 N ± 3.40 and 28.38 N ± 4.80 respectively), three months (30.93 N ± 3.52 and 30.43 N ± 4.7 respectively), six months (30.63 N ± 3.50 and 30.48 N ± 4.63 respectively) and one year (27.13 N ± 3.38 and 27.69 N ± 4.41 respectively). PEEK clips used for retention of PEEK bar-implant retained mandibular overdentures showed comparable retention values to nylon clips up to one year.

FEM simulation of interforaminal mini-implant loss in mandibular overdentures

Stress distribution of different attachment systems in mandibular implant overdentures: A 3D finite element study.

Total edentulism significantly impairs masticatory, nutritional and psychosocial health worldwide, necessitating superior prosthetic rehabilitation solutions beyond conventional complete dentures. Hence, this prospective comparative study evaluated 156 completely edentulous patients over 5 years: implant-supported mandibular overdentures with two locator attachments (n=78) versus conventional complete dentures (n=78). Implant overdentures demonstrated superior 5-year success rates (94.9% vs 76.9%, p<0.001) with acceptable marginal bone loss (1.23±0.42 mm) and consistently higher patient satisfaction scores. Oral health-related quality of life metrics remained significantly improved across all assessment periods in the implant-supported group compared to conventional dentures. Thus, we show prosthodontic standards by establishing implant-supported mandibular overdentures as the minimum treatment protocol for optimal edentulous patient outcomes.

Nylon clip wear affects the retention of implant-retained overdenture. The purpose of the present investigation was to determine the wear of nylon clips and patient satisfaction with either a cobalt-chromium (Co-Cr) metal bar or a milled polyether ether ketone (PEEK) bar in mandibular dentures supported by two implant-retained mandibular overdentures over a one-year clinical study. Twenty edentulous patients were randomly divided into two groups ten patients in each group. Group I (Co-Cr metal bar with nylon clip) and Group II (PEEK bar with nylon clip). In both groups, two implants were placed in the canine–premolar region using a delayed loading protocol. The primary outcome was Nylon clip wear, it was evaluated using volumetric change and surface roughness assessment at insertion, three months, six months, nine months, and one year. Patient satisfaction was evaluated at six months and one year using a visual analog scale (VAS). Data were collected and statistically analyzed to compare the final outcomes between the two groups. The metal group showed significantly higher roughness and volumetric changes with volumetric changes reached 7.49 μm ± 0.47 after 12 months (P=.0001) compared to the PEEK group that reached 7.21 μm ± 0.43 with no difference was found between them at 12 months (P = .188). Patient satisfaction scores were significantly higher in the PEEK group, regarding retention, stability, comfort, and speaking at both 6 months and 1 year (P=.04). Nylon clips showed clinically acceptable wear performance with both PEEK and metal bars after 1 year, and the PEEK bar demonstrated superior surface properties and patient satisfaction, especially in the first 6 months of the study. The study was approved by the Research Ethics Committee of the faculty of dentistry, Cairo University (No 94/23) and registered in the Clinical Trials.gov (NCT06909435). Trial Registration date is 27-03-2025.

This study aimed to compare denture base adaptation and peri-implant soft tissue health between CAD/CAM milled and 3D-printed mandibular implant-assisted overdentures. Twenty-four completely edentulous patients were enrolled and randomly allocated to two groups. After two dropouts, twenty-two patients completed the trial (11 per group). All patients received two implants in the mandibular canine region with ball attachments. The intervention group received a CAD/CAM milled mandibular overdenture, while the control group received a 3D-printed mandibular overdenture; both groups received a conventional maxillary complete denture. Peri-implant soft tissue health was assessed using clinical parameters, including Gingival Index (GI), Plaque Index (PI), Bleeding Index (BI), and Probing depth (PD) at insertion (T0), six months (T6), and one year (T12) after denture insertion. The adaptation of the denture base for both groups was assessed by digital surface matching software (Geomagic). Regarding peri-implant soft tissue health, clinical parameters increased significantly with time for both groups, and there was no significant difference in all parameters between the two groups at all observational times. The whole surface adaptation between the two groups was significantly different, with Group I showing significantly higher adaptation than Group II. Within the limitations of this study, CAD/CAM milled implant-assisted mandibular overdentures demonstrated superior denture base adaptation compared to their 3D-printed counterparts. This finding underscores the precision achievable with subtractive manufacturing for definitive prostheses. Regarding the peri-implant tissues, both groups maintained comparable and stable levels of plaque control and gingival health throughout the observation period.Clinical Trial Registration Number: No. NCT06166446.

To evaluate retention, masticatory performance, and patient satisfaction of complete mandibular dentures retained by four mini-implants (MIs) versus two standard implants (SIs) with functional-immediate loading, and to compare subjective and objective evaluations. Twenty-nine participants, classified according to the American College of Prosthodontists Classification as Class I or II, were edentulous for 6 months to 30 years, with a history of 0-3 previous dentures. Participants were allocated into three groups: Group S (n = 11) received two SIs (3.75mm, Intrahex, Intra-Lock), Group M3 (n = 8), and Group M2.5 (n = 10) received four MIs (3 and 2.5mm, respectively; Inclusive, Prismatik Dentalcraft). Outcomes were evaluated before loading and after 1, 3, 6, 12, and 18 months. Retention was measured with a digital force gauge, patient satisfaction using the McGill Denture Satisfaction Questionnaire, and masticatory performance with the single-sieve method. One-way ANOVA and paired t-test were used (p ≤ 0.05). Retention, masticatory performance, and patient satisfaction improved significantly across all groups (p < 0.01). No intergroup and intragroup significant differences were found, except for retention in Group S, which showed highervalues than MI groups and decreased over time (p < 0.05). According to the results of this study, all groups showed improved retention, masticatory performance, and patient satisfaction. Group S had better retention initially, but it decreased over time. Both MI groups demonstrated similar masticatory performance and patient satisfaction as Group S. MI groups exhibited similar outcomes. Subjective evaluation can be a sufficient alternative to objective tests.

Complete edentulism significantly affects the oral function, facial aesthetics, phonetics, and psychological well-being of individuals. While conventional complete dentures continue to serve as a widely accepted treatment modality, mandibular dentures often suffer from insufficient retention and stability, especially in cases of moderate to severe alveolar ridge resorption. Implant-supported overdentures provide an effective alternative that improves stability, retention, and overall prosthesis performance. The use of bar attachments in mandibular implant-supported overdentures allows splinting of implants, reduces individual stress on implants, distributes occlusal forces, and enhances long-term success. Customized bars fabricated using CAD/CAM techniques, especially in cobalt-chromium, offer a precise, passive fit and improved biomechanical performance. Incorporating ball attachments at the distal ends of the bar, connected to O-rings within the denture, adds an element of resilient retention, increasing rotational resistance and enhancing comfort and function.Implant-supported overdentures have revolutionized the rehabilitation of edentulous patients by offering superior function and comfort. This clinical case report presents the management of a 59-year-old completely edentulous female patient who received an RP-4 mandibular overdenture supported by a customized cobalt-chromium bar with integrated ball attachments. Two Refirm implants were placed at positions B and D, followed by a stepwise prosthetic protocol including impression making, verification, jaw relation, CAD-CAM bar fabrication, denture reinforcement with metal mesh, and final insertion with torque-controlled screw tightening. O-rings were placed in the intaglio surface of the denture corresponding to the ball attachments. Follow-up demonstrated excellent retention, stability, and patient satisfaction.

This study aims to evaluate the marginal bone level changes (MBLC), survival, and success rate of 4 mini-implants (MIs) of two different diameters versus two standard-sized implants (SIs) that were loaded functionally and immediately by a complete mandibular denture. The study comprised 29 participants with conventional complete dentures; they were randomly allocated into three groups. Group S included 11 participants who received two SIs of 3.75 mm diameter, group M3 included 8 participants who received four MIs of 3 mm diameter, and group M2.5 included 10 participants who received four MIs of 2.5 mm diameter. MBLC was evaluated on each implant's mesial and distal sides after 18 months of loading. A paired t-test and one-way ANOVA were used for intragroup and intergroup comparisons, respectively (P ≤ 0.05). The evaluation of survival and success rates adhered to the criteria established by the International Congress of Oral Implantologists in Pisa (2007). Immediate loading was employed in all cases. No failure occurred in any case. The success rate after 18 months was 90.91% in the S group, 90.63% in the M3 group, and 90% in the M2.5 group. MBLC after 18 months of loading were 0.76 ± 0.62 mm mesially and 0.63 ± 0.90 mm distally in the S group, 1.04 ± 0.72 mm mesially and 1.05 ± 0.84 mm distally in the M3 group, and 1.37 ± 0.73 mm mesially and 1.11 ± 0.68 mm distally in the M2.5 group. The SIs group showed better radiographic results and success rates than the MIs groups. As the diameter of the implant decreases, the mean MBLC increases. However, the results of the MIs groups were within acceptable limits. The survival rate was 100% in the three groups.

Ball and locator attachments are widely used for mandibular implant-supported overdentures (IODs), yet long-term comparative data remain limited. This retrospective cohort study evaluated 10-year marginal bone loss (MBL) and peri-implant soft-tissue outcomes in patients restored with two-implant mandibular overdentures. Records of patients treated between 2013 and 2014 were reviewed. Thirty-five patients with complete baseline, 1-, 5-, and 10-year clinical and radiographic data were included. MBL was measured on calibrated panoramic radiographs using a thread-based quantitative method with individualized pixel-millimeter scaling. Probing pocket depth (PPD), plaque index (PI), and gingival index (GI) were recorded at each visit. All measurements were performed by a calibrated examiner blinded to group assignment. Group comparisons were conducted at p < 0.05, and effect sizes were used to support clinical interpretation. Both attachment systems showed stable peri-implant outcomes across the 10-year follow-up. MBL values were comparable between groups (p > 0.05) and remained within clinically acceptable limits. The locator group exhibited a transient mid-term increase in probing depth and gingival index, but these changes were small in magnitude, associated with medium-to-small effect sizes, and resolved by the 10-year evaluation. PI scores were similar between groups at all follow-up intervals. Ball and locator attachments demonstrated comparable 10-year peri-implant outcomes, and the minor mid-term soft-tissue variations in the locator group were transient and clinically insignificant.

This in vitro study compared initial retention forces and long-term degradation patterns of three attachment systems for mandibular implant-retained overdentures: solitary studs, milled bars with sleeves, and milled bars with studs. A simulated mandibular model with three parallel implants received overdentures incorporating each attachment system (n = 10 per group). To simulate 5 years of clinical use, specimens underwent 5400 insertion-removal cycles. Measurement of retention forces via vertical dislodgement (5mm/min) was checked at 12 intervals. Statistical analysis included two-way repeated measures ANOVA and linear regression to study retention degradation patterns. Two-way repeated measures analysis of variance (ANOVA) revealed significant differences in retention stability (p<0.001). Bar systems demonstrated better durability, with bar-sleeves keeping 16.03 ± 0.22 N (86.5% loss) and bar-studs 19.90 ± 0.97 N (82.2% loss) after 5,400 cycles, compared to solitary studs' 5.38 ± 0.21 N (95.8% loss). Linear regression confirmed predictable degradation in bar systems (R2>0.84, slope: -7.23 to -7.03 N/cycle) versus erratic decay in solitary studs (R2 = 0.46). Post-hoc tests showed no significant difference between bar subtypes (p = 0.567). Thesefindings suggest that, under in vitro conditions,splinted bar attachments, regardless of interface design, offer greater long-term retentiondurabilitythan solitary systems, considering their usemay be advantageousin adequate prosthodontic space. The predictable linear degradation pattern of bar systems in thisin vitromodelsuggests a potential mechanical rationale for less frequent maintenance(e.g., clip/matrix replacement every 3-4 years),in contrast to the more rapid and erratic degradation observed for solitary studs, which would imply a need for more frequent intervention in a clinical setting.

This study aimed to compare the retention of cobalt-chromium and polyetheretherketone secondary telescopic crowns in implant-retained mandibular overdentures. Twelve patients were selected for the study, each received 2 implants in the canine region bilaterally to retain a mandibular overdenture with milled telescopic crowns. The primary crowns with 2° occlusal taper were fabricated using milled titanium abutments. Later, the patients were randomly divided into 2 groups: the cobalt-chromium group, where the secondary crowns were fabricated from milled cobalt-chromium alloy, and the polyetheretherketone group, where secondary crowns were constructed from milled polyetheretherketone. Retention was evaluated at the relative geometric center at baseline (zero months), 6, 9, and 12 months postprosthetic loading using a force meter gauge. The mean of 5 retention force readings was recorded in Newtons for each patient at follow-up visits, and the data were subject to statistical analysis. At baseline, after 6, 9, and 12 months, the CoCr group showed statistically significantly lower mean retention value than the PEEK group. A statistically significant decrease in retention forces within both groups was observed after 12 months postprosthetic loading. The present study suggested that milled cobalt-chromium and polyetheretherketone secondary telescopic crowns in combination with titanium primary conical crowns may provide an acceptable treatment option for completely edentulous patients regarding retentive force. The milled polyetheretherketone secondary telescopic crowns may offer higher retentive force compared to milled cobalt-chromium ones in clinical performance. To prefer one of these materials over the other needs more extensive research.

Peri-implant health and patient-reported outcomes in mandibular two-locator overdentures: A 1- to 9-year retrospective cohort study.

Immediate versus conventional loading in users of mandibular overdentures retained by narrow-diameter implants: results from a 5-year randomized clinical trial.

The purpose of this prospective 12-year long-term follow-up of a randomized clinical trial was to evaluate clinical and radiographic outcomes of two implants placed using either an immediate loading (IL) or delayed loading (DL) protocol to support a non-splinted, locator-retained mandibular overdenture. Twelve eligible patients were enrolled, with six in the IL group and six in the DL group. Clinical and standardized radiographic examinations were conducted to assess implant survival, and peri-implant hard and soft tissue health. Patient-reported outcomes (PROs) were collected, and the incidence and nature of prosthetic complications documented. The data for 5-year follow up of the RCT is reported in a previous publication. No statistically significant difference in radiographic bone levels (∆RBL) was observed between IL and DL groups during the 5-12 year or 0-12-year intervals. One implant was lost in the DL group between the 5-12-year period, resulting in a cumulative implant survival rate (CSR) of 96% for DL and 100% for IL at 12 years. At the 12-year follow-up, no significant differences were observed between IL and DL groups with respect to clinical outcomes such as probing depths (PPD), plaque score (PS), keratinized tissue width (KTW) and apical migration of the free gingival margin (GM). PROs related to patient comfort and satisfaction were similar in IL and DL groups. Major prosthetic complications occurred in 50% of patients, while 92% experienced at least one minor prosthetic issue. A temporal trend of increase in radiographic bone loss, decrease in KTW, and increase in GM from baseline to 12 years was noted in both IL and DL groups. Both immediate and delayed loading protocols demonstrated comparable long-term patient comfort, patient satisfaction, clinical and radiographic performance when applied to two non-splinted, locator-retained implants supporting a mandibular overdenture. Within the limitations of the present investigation, immediate loading may represent a reliable and potentially favorable treatment approach for mandibular overdentures in appropriately selected cases. Significant prosthetic complications were noted in both groups, which highlights the importance of regular recall and prosthetic maintenance for long-term success.

Background: Implant-retained overdentures are now the preferred treatment for mandibular removable dentures. However, there is a lack of comprehensive clinical studies comparing the performance of a single mini dental implant to conventional dental implant for implant-retained mandibular overdentures. The aim of the study is to evaluate the crestal bone loss and the patient satisfaction between single conventional and mini-implant supported mandibular overdenture.Materials and Methods: 22 participants satisfying the predetermined inclusion and exclusion criteria were selected. The participants were randomly assigned into two groups (Group A – Conventional implant and Group B – Mini implant). Each group had 11 participants; a single implant was placed in symphysis of the mandible. Conventional loading protocol was followed after 3 months. Crestal bone loss was assessed with CBCT at mesial, distal, buccal, lingual sites immediately after implant placement, 3rd month (loading), and 9th month from implant placement. Patient satisfaction was evaluated with a questionnaire at the end of 9th month.Results: There was no statistical significance between the two groups immediately after placing the implant. At 3rd and 9th month the crestal bone loss was higher in conventional implant group. Overall, the patient satisfaction showed no statistical difference between the two groups.Conclusion: Mini-implants show promising results in terms of lower crestal bone resorption and certain aspects of patient satisfaction compared to conventional implants. These findings support the consideration of mini implants as a preferable option in specific clinical scenarios.

Abstract Aim: The aim of this in-vitro study was to comparatively evaluate cobalt–chromium chains versus polyether ether ketone chains for reinforcing single implant-assisted mandibular overdentures using CAD/CAM and conventional techniques. Materials and methods: Four identical mandibular epoxy resin models, each covered by a 2 mm silicone resilient layer simulating the mucosa, were used. A single implant was inserted in the midline region of each model, and four identical mandibular overdentures were fabricated on the edentulous models. The four models were divided into four groups. A strain gauge was used to measure the strain around the implant upon the application of vertical and oblique loads. Results: The highest strain was recorded in group A, while the lowest was observed in group D. There were significant differences between groups A and B and groups C and D under both vertical and oblique loading. A significant difference was also observed between groups A and C, except at the buccal and lingual surfaces under oblique loading. On the other hand, there was no significant difference between groups B and D, except at the buccal, lingual, and distal surfaces under oblique loading. Analysis of variance testing revealed a significant difference among the four groups. Conclusion: Overdentures reinforced with cobalt–chromium produced more strain on the implant than those reinforced with polyether ether ketone. Significant differences were found between groups A and B and groups C and D under vertical and oblique loads.