Maxillary Four Implant-retained Overdentures via Locator® Attachment: Intermediate-term Results from a Retrospective Study

Do dental implants installed in different types of bone (I, II, III, IV) have different success rates? A systematic review and meta-analysis

Purpose

The objective of this systematic review and meta-analysis was to evaluate the survival rate of implants installed in bone type IV (Lekholm and Zarb, 1995) compared to that of implants installed in bone types I, II, and III.

Material and methods

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA) and was registered in the PROSPERO International Database of Systematic Reviews (CRD42021229775). The PubMed/MEDLINE, Scopus, and Cochrane databases were searched through July 2021. The PICO question was: "Dental implants installed in type IV bone have a lower success rate when compared to implants installed in type I bone, II and III?". The established inclusion criteria were: 1) controlled and randomized clinical trials (RCT), 2) prospective and retrospective studies with at least 10 participants with dental implants, and 3) patients with dental implants installed in bone tissue types I, II, III, and IV (Lekholm and Zarb, 1985). The minimum followup duration was 1 year.

Results

After searching the identified databases, 117 articles were selected for full reading and 68 were excluded. Thus, 49 studies were included for qualitative and quantitative analyses. The total number of participants included was 12,056, with a mean age of 41.56 years and 29,905 implants installed. Bone types I, II, and III exhibit a lower implant failure rate when compared to bone type IV.

Conclusion

Dental implants installed in bone types I, II, and III showed significantly higher survival rates than those installed in type IV. The bone type I success rate was not significantly different than that of type II; however, the success rate of bone type I and II was higher than that of type III.

Articulation distortion in Mandarin-speaking individuals with complete arch maxillary implant-supported fixed dental prostheses

STATEMENT OF PROBLEM

Implant-supported fixed dental prostheses (IFPs) have been increasingly used to restore edentulous jaws, yet few studies have utilized acoustic analysis for objective evaluation of postrestoration speech outcomes.

PURPOSE

The purpose of this clinical study was to assess speech articulation in edentulous individuals before and after the provision of IFPs by combining the results of subjective evaluations and objective acoustic analysis parameters.

MATERIAL AND METHODS

The study included thirty-four individuals who had an edentulous maxilla and had been provided with an IFP for over 6 months, along with 6 dentate controls. Acoustic analysis was conducted, and mean opinion scores (MOS) were rated from recordings. The participants were interviewed about perceived speech changes. Changes in the parameters were evaluated using the paired t test or Wilcoxon signed-rank test (α=.05). A comparison between dentate controls and edentulous individuals (with or without prostheses) was made using an independent t test or Mann-Whitney U test (α=.025).

RESULTS

Following restoration, the center of gravity (CoG) changes occurred in 11 of 12 consonants in edentulous individuals (P<.05). Prosthesis use allowed the CoG of all affricates and fricatives to appear larger and closer to control values. Before restoration, the CoG of 9 of 12 consonants in edentulous individuals differed from controls (P<.01); after restoration, this reduced to 3 out of 12 (P<.01). MOS improved in 10 of 12 consonants (P<.01), nearing a score of 4. Despite restoration, the CoG of alveolo-palatals [tɕh], [tɕ], and [ɕ] remained different from controls (P<.01). Most participants were satisfied with the improvement, with few reporting discomfort with alveolars [s] and [tsh].

CONCLUSIONS

IFPs can enhance speech in edentulous individuals, yet articulation distortions of alveolar and alveolo-palatal consonants persist. The improper palatal shape of IFPs or an abrupt joint between the IFP and atrophic natural bone may contribute to these distortions.

Maxillary implant overdentures retained with bars or solitary attachments: A 5-year randomised controlled trial

Purpose To compare the 5-year follow-up outcomes of maxillary overdentures retained by bars or solitary attachments.Methods Fifty consecutively selected fully edentulous patients experiencing problems with their conventional denture received four implants and were randomly allocated to receive a maxillary overdenture with either bar- or solitary attachment retention. Marginal bone level change (primary outcome), implant- and overdenture survival rate, clinical- and patient related outcome measures were recorded at baseline, and after 1 and 5 years. Biological and technical complications were recorded throughout the entire follow-up period.Results After 5 years, the mean marginal bone level change was higher in the solitary attachment group (-1.41±1.38mm, P=0.024) than in the bar group (-0.99±0.96mm). Also, fewer implants survived in the solitary attachment group (89.5%, P=0.027) than in the bar group (96.3%). The overdenture survival rate was 95.0% and 91.3% in the bar and solitary attachment group, respectively. Although the clinical and patient related outcomes were favourable and did not differ significantly between the groups, the peri-implantitis incidence was 25.8% in the solitary attachment group and 5.1% in the bar group. Any technical complications were minor.Conclusions In maxillary 4-implant overdenture therapy, the marginal bone level, implant survival rate and the number of complications are better with bar attachments than with solitary attachments. Both groups' clinical and patient related outcome measure scores were equal throughout the entire follow-up period.

Maxillary implant overdenture retained by four unsplinted attachments and opposed by a natural or fixed dentition: Five-year clinical outcomes. A prospective case series

OBJECTIVES

The objective of this study was to assess, over a period of 5 years, implant prosthesis and patient-reported outcomes of complete dentures retained by four implant-supported attachments in the edentulous maxilla facing either natural teeth or fixed rehabilitation in the lower jaw.

MATERIALS AND METHODS

Implant, prosthodontic and patient-related outcomes were assessed in 30 patients at 1, 3 and 5 years. Prosthodontic survival, complications or maintenance events as well as implant survival were recorded. Patient-reported outcome measures (PROMs) were evaluated with the Oral Health Impact Profile (OHIP-20) questionnaire and a visual analogue scale (VAS) before implant placement (baseline) and during the follow-up period.

RESULTS

After 5 years, three patients dropped out, 21 implants failed, and four overdentures were replaced leading to a prosthesis survival rate of 85.2% (95% CI: 71.8%-98.6%) and an implant survival rate of 80.6% (95% CI: 73.1%-88.0%). Prosthodontic success rate decreased from 86.2% to 74% between the 1st and the 3rd year and reached 63% after 5 years. OHIP results improved significantly from baseline to 1 year (p < .0001) and to 3 years (p = .036), but, at 5 years, the improvement was no longer significant when compared to baseline (p = .12). The overall VAS score remained significantly higher up to 5 years (p < .001).

CONCLUSION

A substantial number of prosthetic complications and replacements occurred over the 5-year follow-up. After 5 years, the OHIP-20 deteriorated and reached again the baseline level. Nonetheless, the VAS results suggest significantly increased patient satisfaction after implant-supported retention was provided for the removable prostheses.

Maxillary overdenture on three implants retained by low-profile stud attachments - A prospective cohort study

BACKGROUND

Clinical data are needed on long-term outcomes of removable implant-supported prostheses in the fully edentulous maxilla as a function of the number of implants, effects of the attachment system and other clinical variables.

OBJECTIVE

To restore individuals with an edentate maxilla with a metal-reinforced removable prosthesis without palatal coverage retained by low-profile stud attachments on three implants.

METHODS

The regional ethics committee approved a prospective cohort study that included all consecutive patients treated in a private speciality clinic. Primary outcomes were patients reported, that is denture satisfaction scale and oral health-related quality of life - OHIP-20. Secondary outcomes were implant- (bone loss, implant complications and peri-implant conditions) and prosthesis-related (prosthesis complications, maintenance needs and mucosa condition).

RESULTS

Thirty-two study participants were recruited between March 2007 and October 2016 and followed for a minimum of five years. According to Kruskal-Wallis tests, the OHIP-20 and Denture Satisfaction Scale questionnaire pre-treatment scores differed significantly. After an average of 6.7 years, peri-implant bone loss of more than 2 mm was observed on 17% of all implants, while no or minor bone loss was seen on 38%. The estimated success of implants was 0.95 at 168 months. The estimated success of the prosthesis, that is no adverse events or need for any repairs, was 0.55 at 156 months.

CONCLUSION

The positive findings in the current clinical study strengthen the notion that for many individuals with an edentulous maxilla, a removable prosthesis retained by three implants fitted with low-profile stud-attachment is a reliable technical solution.

Cost and complications associated with implant-supported overdentures with a resilient-attachment system: A retrospective study

STATEMENT OF PROBLEM

Implant-supported overdentures with a splinted or nonsplinted attachment system have been a successful treatment option for edentulous mandibles with excessive hard tissue resorption. Currently, the 2 most common treatment approaches for an implant overdenture uses either a bar attachment system (splinted) or resilient (LOCATOR)-attachment system (nonsplinted). The LOCATOR-attachment system is often chosen for the lower initial cost. However, whether the ongoing maintenance costs of the LOCATOR-attachment system increase the overall cost of this system is unclear.

PURPOSE

The purpose of this retrospective study was to investigate the frequency of maintenance procedures, complications, and costs associated with the LOCATOR-supported overdenture treatment.

MATERIAL AND METHODS

The retrospective data of 75 patients who had received implant-supported overdentures with LOCATOR-attachments at the University of Colorado School of Dental Medicine in the previous 10 years were collected and screened to evaluate the number of maintenance visits, type of complications, and cost (actual fees for the service) of the maintenance visits. The data were analyzed, and the mean values calculated.

RESULTS

The average number of maintenance visits was 7.7 in the mean observation time of 5.2 years. Replacement of the attachment was the most frequent complication (63%). The average maintenance cost charged to the patient for maintenance was 56.2% ($795) of the initial cost over the average 5.2 years of follow-up. The average total maintenance cost (actual fees for the service) was 95.4% ($1349) of the initial cost over the average of 5.2 years of follow-up. The average maintenance cost adjusted or lost over the 5.2 years follow-up was 39.2%.

CONCLUSIONS

The 5-year costs for the maintenance of mandibular overdentures with a LOCATOR-attachment system were equal to or higher than the initial cost of the treatment. The number of maintenance visits and the cost were higher for patients who were older than 75 years.

Maxillary implant overdenture retained by four unsplinted attachments and opposed by a natural or fixed dentition: One-year clinical outcomes

OBJECTIVES

The aim of this prospective study was to evaluate the implant, prosthesis, and patient-reported outcomes of maxillary removable prostheses retained by 4 implant-supported study abutments after a follow-up period of 1 year in patients with natural teeth or a fixed rehabilitation in the mandible.

MATERIALS AND METHODS

A total of 30 patients were included, and all received 4 implants in the upper maxilla. After 12 weeks, the prostheses were connected to the implant with unsplinted attachments. The implant and prosthodontics outcomes were assessed over a follow-up period of 1 year. Patient-reported outcome measures (PROMs) were evaluated with the Oral Health Impact Profile (OHIP-20) questionnaire and an adaptation of the McGill Denture Satisfaction Instrument using a visual analogue scale (VAS).

RESULTS

A single patient dropped out. At the post-operative 12-week follow-up, 79.3% (95% CI: 64.6%-94.1%) of the patients displayed peri-implant mucosa hyperplasia and 69.0% (95% CI: 52.1%-85.8%) showed pain. After 1 year, 16 implants failed in 10 patients, leading to an implant survival rate of 86.2% (95% CI: 79.0%-92.5%), and the mean peri-implant bone loss was 1.01 ± 0.77 mm (95% CI: 0.85-1.16 mm). The prosthesis survival rate was 96.6% (95% CI: 82.2%-99.9%). The OHIP-20 and VAS scores both improved significantly from baseline to 1 year (p < .001).

CONCLUSION

The implant survival rate was lower compared to the literature for the upper maxilla. Despite the encountered problems, PROMs showed significant improvement with the implant overdenture retained by 4 unsplinted implants compared to conventional dentures.

Maxillary Implant-Supported Overdentures: Mechanical Behavior Comparing Individual Axial and Bar Retention Systems. A Cohort Study of Edentulous Patients

Background and objectives: To compare the medium- to long-term mechanical behavior of overdentures with two different retention systems: overdentures with Locator® axial retention, and vertical insertion overdentures with bar retention, used to rehabilitate edentulous maxillar. Material and Methods: This prospective study assessed patients presenting complete maxillary edentulism, rehabilitated by means of implant-supported overdentures (n = 20), 10 with Locator® axial retention (ODA group) and 10 with overdentures on bars (ODB group). Patients also completed a questionnaire to determine their satisfaction with treatment. Results: The mean follow-up time in both groups was 11.4 years, with follow-up times in both groups ranging from 5 to 14 years. The ODA group suffered mechanical complications such as retention loss, need for nylon retention insert changes, resin fracture, and need for relining. In the ODB group, prosthetic dental wear, screw loosening, and complete prosthetic failure were more common. A total of 19 implants failed (23.8%); of these, 11 were in the ODA group (failure rate = 27.5%) and eight in the ODB group (failure rate = 20%). The patient satisfaction questionnaire obtained a mean score of 7.9 out of 10 in the ODA group, and 9.75 in the ODB group. Conclusions: in rehabilitations of edentulous maxillar by means of implant-supported overdentures, both the systems assessed were shown to be effective in the medium to long term. Patients expressed a high level of satisfaction with the treatments received.

Use of an attachment system with angulated abutments and polyetheretherketone inserts to retain a maxillary overdenture: A clinical report

This clinical report describes the rehabilitation of a maxillary edentulous arch with a current overdenture attachment system with angulated prefabricated abutments and polyetheretherketone (PEEK) inserts. Prefabricated angulated abutments were used on previously and recently placed diverging implants, which enabled a common path of insertion for the overdenture to be established during fabrication.

Maxillary implant overdentures retained by use of bars or locator attachments: 1-year findings from a randomized controlled trial

PURPOSE

Comparison of outcomes of maxillary implant overdentures retained by use of either locator attachments or bars in a 1-year randomized controlled trial.

METHODS

Fifty edentulous participants received four maxillary implants. They were allocated to two groups (n = 25) differing in type of prosthetic attachment used to retain the maxillary prosthesis: either locator attachments or bars were applied. After one year, implant and overdenture survival was assessed. Peri-implant hygiene (Plaque-index, presence of calculus), soft tissue conditions (Gingiva-index, Sulcus Bleeding-index and pocket probing depth) and patient satisfaction (oral health impact profile (OHIP-49), denture complaints questionnaire and general satisfaction score (GSS)) were compared. The peri-implant bone level was estimated using intra-oral radiographs (student T-test).

RESULTS

Implant survival was 96.7% in the locator group and 97.9% in the bar group. No overdentures had to be remade. Patient satisfaction was significantly greater in the bar group when rated by OHIP-49 sum score and by GSS. When comparing the denture complaints questionnaire and the separate OHIP-49 item scores, no significant difference was found. There was not a significant difference in hygiene and soft tissue conditions. Marginal bone loss was estimated 0.58 ± 0.71 mm for locators and 0.31 ± 0.47 mm for bars.

CONCLUSIONS

Maxillary overdentures on four implants retained by bars or locators were compared. Bone loss was within an acceptable range for both groups after 1 year. However, less bone was lost in the bar group. Even though both treatment options improved patient satisfaction, bars seem to be particularly beneficial with regard to OHIP-49 sum score.

Clinical evaluation of inter-implant distance influence on the wear characteristics of low-profile stud attachments used in mandibular implant‑retained overdentures

Background

This study was aimed to evaluate the influence of inter-implant distance on the wear characteristics of low-profile stud attachments used in mandibular implant retained overdentures.

Material and Methods

Forty Completely edentulous participants aged between 50 - 70 years were enrolled in this study. Each patient received 2-implants by 2-stage submerged surgical protocol. Participants categorized into 4-groups. Group I: 19 mm inter-implant distance with Locator retained overdentures; Group II: 19 mm inter-implant distance with OT Equator retained overdentures; Group III: 25 mm inter-implant distance with Locator retained overdentures; Group IV: 25 mm inter-implant distance with OT Equator retained overdentures. The female housings of each attachment were picked up to the mandibular overdenture. 12 month later the male inserts were replaced by new one. The used retentive male inserts were examined by Stereomicroscopic.

Results

Stereomicroscopic examination revealed wear were detected on both inner surface and, the core of male inserts. Comparison between the unused and the used Locator and OT equator retentive male inserts at various inter-implant distance revealed highly significant wear changes between them at either 19 mm, or 25 mm inter-implant distance P1= .000, P2=.000 respectively.

Conclusions

After one year of implant overdenture clinical use; both locator and OT equator retentive male inserts revealed significant surface deformities and wear. Wear were more notable on both locator and OT equator retentive male inserts with 25 mm interimplant distance than with 19 mm interimplant distance. Key words:Inter-implant distance, attachments wear, locator retentive male inserts, OT equator retentive male inserts.

Multicenter Retrospective Analysis of Implant Overdentures Delivered with Different Design and Attachment Systems: Results Between One and 17 Years of Follow-Up

PURPOSE

To analyze implant and prosthetic survival rates, complications, patient satisfaction, and biological parameters of patients rehabilitated with implant overdentures (IOV) on splinted and nonsplinted implants and different attachment systems, in function for one to 17 years.

METHODS

This retrospective study evaluated data collected from patients rehabilitated with implant overdentures between January 2001 and December 2016 in nine different centers. Outcome measures were implant and prosthetic success rates, mechanical complications, marginal bone loss (MBL), oral health impact profile (OHIP), bleeding on probing, and plaque index.

RESULTS

A total of 581 implants were installed in 194 patients. Patients were followed for a mean period of 60.6 months (range 6⁻206). Eighty-nine patients received 296 low profile attachment (OT Equator), 62 patients received 124 ball attachments, and 43 patients received 107 Locator attachments. In eighty-three patients the implants were splinted with computer aided design/computer aided manufacturing (CAD/CAM) or casted bar. At the last follow-up, 10 implants failed in eight patients. Statistical significance was found for failed prostheses (P = 0.0723) and complications (P = 0.0165), with better values for splinted implants. No statistically significant differences were found in proportion of implant and prosthetic failure (P > 0.05). At a five-year follow-up, proportion of complications (P = 0.0289) and failed prostheses (P = 0.0069) were statistically higher for IOV on Locator attachments. No difference was founded in MBL at one- and two-year follow-up between different attachment systems (P > 0.05). Statistically significant improvement in all the OHIP categories was reported in all the patients, after one year of function.

CONCLUSIONS

Implant overdenture showed high implant and prosthetic survival rates, low complications, high patient satisfaction, and good biological parameters in the long-term follow-up. Splinting the implants may reduce number of mechanical complications. Locator attachments showed higher number of complications. Further studies are needed to confirm these preliminary results.

The number of implants required to support a maxillary overdenture: a systematic review and meta-analysis

PURPOSE

The number of implants needed to support a maxillary overdenture is still a controversial issue. The aim of this systematic review was to investigate the number of implants required to support a maxillary overdenture in order to obtain optimal treatment outcomes in terms of implant survival, overdenture longevity and patient satisfaction.

STUDY SELECTION

Pubmed and EMBASE databes were systematically searched and complemented by hand searching from 2000 to 2017. The Prisma statement and a PICOS approach were adopted. All selected articles provided at least two-year follow-up and 10 totally edentulous patients. Survival rate of implants and overdentures were statistically analyzed according to number of implants and according to splitting technique, employing non-parametric Fisher Test for unpaired data. For the pooled analysis of implant failures, the odds ratio between group of 4 splinted implants and group of more than 4 splinted was calculated.

RESULTS

A total of 28 articles were included. Data analysis of the included studies showed that the survival rate of implants appeared higher in ≥ 4 implants group, whereas the high survival rate of overdentures and patient satisfaction were not significantly influenced by the number of implants.

CONCLUSIONS

The findings of our analysis indicate that overall the most frequent tendency is to place at least four implants, splinted or unsplinted, in order to ensure a higher survival rate of implants. However, the relationship between overdenture survival, the patient's quality of life, and the number of implants required to support a maxillary overdenture has yet to be clarified.

Clinical performance of LOCATOR® attachments: A retrospective study with 1-8 years of follow-up

The use of LOCATOR® attachments in implant-supported removable dental prostheses (ISRDPs) has been evidenced with conflicting clinical behavior in literature. This retrospective study aimed to investigate the long-term clinical performance of LOCATOR® attachments by evaluating the frequency of the encountered mechanical complication events (MCEs) and the factors that play a role in attachment wear (AW). The study recruited participants with ISRDPs on LOCATOR® attachments. Clinical parameters, number of MCEs (attachment replacements, attachment loosenings, denture cap-related events, loss of retention and/or insert, and implant fractures), and AW were recorded. Nonparametric tests were applied for statistical analyses (𝛼=0.05). Baseline demographics for the recruited 47 participants (mean age: 72.0 ± 9.0 years) revealed an implant survival rate of 94.9% (mean observation period: 54.8 months), average peri-implant probing depths, bleeding on probing scores, and plaque scores of 1.80 ± 1.50 mm, 0.70 ± 0.90, and 0.81 ± 0.90, respectively. MCEs were directly influenced by the time in use (p < 0.001). The most frequently encountered MCEs were loss of retention (p < 0.001) and denture cap-related complications (p = 0.004). AW was found to be significantly higher in the maxilla than in the mandible (p = 0.028); in the maxilla, the vestibular (p = 0.005) and mesial (p = 0.01) aspects were the most common wear sites. Maxillary implant overdentures revealed more vestibular AW (p = 0.013). In prostheses supported by >3 implants, vestibular (p = 0.046) and mesial (p = 0.032) AW were common. Lingual AW (p = 0.021) was observed more frequently when the support was <3 implants. Loss of retention and AW are the most common complications encountered with LOCATOR® attachments. Therefore, a modification in the attachment design along with an amelioration of the attachment surface may help decrease the maintenance needs and further enhance its clinical performance.

Influence of Number of Implants and Attachment Type on Stress Distribution in Mandibular Implant-Retained Overdentures: Finite Element Analysis

AIM:

This study aimed to compare the stresses generated by using two or four root form dental implants supporting mandibular overdentures that were retained with ball and locator attachments.

METHODS:

Under ANSYS environment, four 3D finite element models were prepared. These models simulated complete overdentures supported by two or four implants with either ball or locator attachments as a connection mechanism. The models’ components were created by CAD/CAM package then were imported to ANSYS. Load of 100 N was applied at the right premolar/molar region vertically and at an oblique angle of 110° from lingual direction.

RESULTS:

Within the conditions of this research, in all cases, it was found that cortical and cancellous bone regions were the least to be stressed. Also, the ball attachment produced higher stresses.

CONCLUSION:

Caps deformation and stresses are negligible in cases of using locator attachment in comparison to ball attachments. This may indicate longer lifetime and less repair/maintenance operations in implant overdentures retained by locator attachments. Although the study revealed that bone was insensitive to a number of implants or attachment type, it may be recommended to use two implants in the canine region than using four, where the locator attachments were found to be better.

Implant Supported Fixed Restorations versus Implant Supported Removable Overdentures: A Systematic Review

AIM:

The aim of this study is to systematically evaluate and compare implant retained fixed restoration versus implant retained over denture.

MATERIAL AND METHODS:

Search was made in 2 databases including PubMed and PubMed Central. Title and abstract were screened to select studies comparing implant retained fixed restorations versus implant retained removable overdentures. Articles which did not follow the inclusion criteria were excluded. Included papers were then read carefully for a second stage filter, this was followed by manual searching of bibliography of selected articles.

RESULTS:

The search resulted in 5 included papers. One study evaluated the masticatory function, while the other 4 evaluated the patient satisfaction. Two of them used Visual Analogue Scale (VAS) as a measurement tool, while the other two used VAS and Categorical Scales (CAT). Stability, ability to chew, ability to clean, ability to speak and esthetics were the main outcomes of the 4 included papers.

CONCLUSION:

Conflicting results was observed between the fixed and removable restorations.

Clinical evaluation of mandibular implant overdentures via Locator implant attachment and Locator bar attachment

PURPOSE

The aim of this study was to evaluate the clinical findings and patient satisfaction on implant overdenture designed with Locator implant attachment or Locator bar attachment in mandibular edentulous patients.

MATERIALS AND METHODS

Implant survival rate, marginal bone loss, probing depth, peri-implant inflammation, bleeding, plaque, calculus, complications, and satisfaction were evaluated on sixteen patients who were treated with mandibular overdenture and have used it for at least 1 year (Locator implant attachment: n=8, Locator bar attachment: n=8).

RESULTS

Marginal bone loss, probing depth, plaque index of the Locator bar attachment group were significantly lower than the Locator implant attachment group (P<.05). There was no significant difference on bleeding, peri-implant inflammation, and patient satisfaction between the two denture types (P>.05). The replacement of the attachment components was the most common complication in both groups. Although there was no correlation between marginal bone loss and plaque index, a significant correlation was found between marginal bone loss and probing depth.

CONCLUSION

The Locator bar attachment group indicates lesser marginal bone loss and need for maintenance, as compared with the Locator implant attachment group. This may be due to the splinting effect among implants rather than the types of Locator attachment.