Effect of implant loading protocols on failure and marginal bone loss with unsplinted two-implant-supported mandibular overdentures: systematic review and meta-analysis

Single Implant-Retained Mandibular Overdentures: A Literature Review

The absence of teeth, known as edentulism, poses considerable obstacles in prosthodontic care and greatly affects a person's well-being. Conventional complete dentures frequently lead to problems like instability and insufficient retention, especially in the lower jaw. Fortunately, the introduction of dental implants has transformed the way we approach edentulous patients, as they now offer support and enhanced retention for removable prostheses, thus revolutionizing their treatment. While a consensus exists on using two implants for retaining mandibular overdentures, the associated cost may be prohibitive for economically disadvantaged individuals. As a solution, the concept of single implant-retained mandibular overdentures has emerged, catering to individuals with limited financial resources and complete tooth loss. This review explores the efficacy and suitability of the single implant overdenture approach, along with an overview of treatment options for edentulous patients, including traditional dentures, tooth-supported overdentures, and implant-supported overdentures. The preservation of bone, improvements in functional abilities, and psychological benefits associated with overdentures are discussed. Moreover, various classifications and prosthetic options for implant overdentures, specifically for mandibular cases, are presented. This literature review aims to provide a comprehensive understanding of possible treatment options and focus on the single implant-retained mandibular overdenture approach and its implications in prosthodontic rehabilitation for edentulous patients.

Fabrication of a Definitive Obturator for a Patient With a Maxillary Defect: A Case Report

Maxillectomy defects can lead to oroantral communication, causing difficulties with chewing, swallowing, speech, and facial appearance. Prosthodontists play a crucial role in rehabilitating such defects using obturators. This case report presents the fabrication of a definitive obturator with a cast metal framework for a patient who had an acquired maxillary defect and previously experienced issues with an ill-fitting obturator. In this clinical report, the patient's canine teeth on both sides and the premolars and molars on the left side were used for rest placement. Retention was achieved by utilizing the remaining teeth, employing two embrasure Aker clasps on the left molars and premolars and a C-wrought wire clasp on the right canine. A complete palate was designed as the major connector to ensure optimal load distribution to the surrounding tissues. Additionally, an indirect retainer was planned for the right canine. This definitive prosthesis rehabilitated the patient, improving masticatory efficiency, enhancing speech clarity, and improving quality of life.

Immediate versus conventional loading of mandibular implant-retained overdentures: a 3-year follow-up of a randomized controlled trial

OBJECTIVES

There is a scarcity of randomized clinical trials (RCT) that report medium- and long-term results and a lack of consensus in the literature on the predictability of immediately loaded unsplinted narrow diameter implants supporting mandibular overdentures. This RCT compared the performance of conventional (CL) and immediate loading (IL) of mandibular overdentures retained by two narrow-diameter implants for 3 years.

MATERIALS AND METHODS

Patients from an RCT treated with CL or IL were invited to attend to 2- and 3-year follow-ups. Clinical, radiographic, functional, and oral health-related quality of life parameters were evaluated. Prosthetic maintenance events, biological complications, and success and survival rates were also recorded. The data were tested by multilevel mixed-effects linear regression analysis and chi-squared tests.

RESULTS

The 1-year survival rates of 90% in the CL group and 85% in the IL group were maintained as no implants were lost between 1 and 3 years. The marginal bone loss (MBL) in the IL group was significantly lower after year 3 (-0.04; p < 0.01). Significant changes were found only for the intra-group comparisons in the third year of function: (i) CL and IL presented similar progression of implant stability, MBL, and posterior bone area resorption; (ii) while CL started deteriorating of masticatory function, IL still exhibited functional evolution and (iii) oral comfort domain in the CL and pain domain in the IL were improved.

CONCLUSION

Although IL experienced the lowest MBL after 3 years, the outcomes showed that both loading protocols result in predictable medium-term rehabilitation when monitored annually.

CLINICAL RELEVANCE

It can be expected that in the third year of function, patients with immediate loading may present more complaints related to general performance even with acceptable masticatory function and self-reported improvements in oral comfort.

Impact of Acrylic and Silicone-Based Soft-Liner Materials on Biting Force and Quality of Life of the Complete Denture Wearers: A Randomized Clinical Trial

This rerandomized clinical trial evaluated the influence of soft liners (SL) on biting force, pain perception, and the oral health-related quality of life (OHRQoL) of complete denture wearers. Twenty-eight completely edentulous patients complaining of ill-fitting lower complete dentures were selected to participate in the study from the Dental Hospital, College of Dentistry, Taibah University. All patients received new complete maxillary and mandibular dentures; then they were randomly divided into two groups (14 patients in each group): the acrylic-based SL group, in which the mandibular denture was lined with an acrylic-based soft liner, and the silicone-based SL group, in which the mandibular denture was lined with a silicone-based soft liner. OHRQoL and maximum bite force (MBF) were assessed in this study before denture relining (baseline), then at one month and three months after relining. The finding showed that both treatment modalities significantly improved the OHRQoL of included patients at one-month and three-month periods compared to baseline records (i.e., dentures before relining) with a statistically significant difference (p < 0.05). However, there is no statistical difference between groups at the baseline, one-, and three-month follow-up periods. Regarding maximum biting force, when acrylic-based SL is compared to silicone-based SL, there is no statistical difference between groups at baseline (75 ± 31 and 83 ± 32 N) and one-month follow-up periods (145 ± 53 and 156 ± 49 N); however, after three months of function, the silicone-based group recorded 166 ± 57 N statistically significant high biting force compared to the acrylic-based group that recorded 116 ± 47 N (p < 0.05). Permanent soft denture liners positively affect maximum biting force, pain perception, and OHRQoL more than conventional dentures. After three months, silicone-based SL outperformed acrylic-based soft liners in maximum biting force, which may indicate better long-term results.

LEVELS OF SMOKING AND PERI‑IMPLANT MARGINAL BONE LOSS: A SYSTEMATIC REVIEW AND META-ANALYSIS

AIM

This systematic review and meta-analysis sought to determine if there was a significantly enhanced risk of peri‑implant marginal bone loss (MBL) due to the increased number of cigarettes smoked per day.

MATERIALS AND METHODS

Six databases, including Medline, Embase, Cochrane Library, Web of Science, Scopus, and ProQuest, were searched until February, 2021. The search terms "dental implant, oral implant, smoking, smoker, non-smoker, marginal bone loss and crestal bone loss" were used in combination to seek the articles providing data for MBL related to the smoking habit. Articles were excluded if the quantity of cigarettes smoked per day was not reported. Random-effects meta-analyses were used to pool the estimates of mean difference (MD) with 95% confidence intervals (CI).

RESULTS

Eight studies were included for qualitative and 5 for quantitative synthesis. The meta-analyses revealed higher levels of MBL in patients who smoked <10 or >10 cigarettes/day than in non-smokers (<10: (MD -0.33, 95% CI -0.69-0.03 and >10: MD -0.58, 95% CI -0.96- -0.19). There was a significant risk of MBL between patients who smoked >10 and <10 cigarettes/day (MD -0.23, 95% CI -0.47-0.01).

CONCLUSION

It seems the risk of MBL is steadily increasing as daily smoking increases.

Masticatory performances and maximum occlusal forces of immediate and conventional loaded two-implant supported overdentures retained by magnetic attachments: preliminary study of randomized controlled clinical trial

Background

The appropriate loading protocol to improve masticatory performance (MP) is still unclear in elderly patients and two-implant overdentures (2-IODs) wearers. This study aimed to compare the long-term MP and maximum occlusal force of immediate loading (IL) and conventional loading (CL) of 2-IODs retained by magnetic attachments. Nineteen edentulous patients were randomly assigned to either an IL (n=10) or CL group (n = 9). In the IL group, the implant was loaded on the same day as insertion, whereas it was loaded 3 months after insertion in the CL group. Magnetic attachments were used to retain all overdentures to the implants. MP, measured by a piece of color-changeable chewing gum and a gummy jelly test, and maximum occlusal force, measured using an occlusal force measuring device, were assessed in both groups at baseline and at 3-, 4-, and 5-year follow-ups.

Results

No significant differences were observed in the MP and the maximum occlusal force between the IL and CL groups at any time point. However, a significantly higher MP was observed at the 3-year time point in the IL group (P = 0.036). The maximum occlusal force revealed a significant correlation with MP, both with the color-changeable chewing gum and gummy jelly at 5 years.

Conclusion

After long-term observation, no significant differences in MP and maximum occlusal force were observed between the IL and CL groups. However, compared to pre-implant insertion of the complete denture, the MP in the IL group significantly improved at 3 years. Furthermore, the maximum occlusal force was significantly correlated with MP at 5 years.

Trial registration

UMIN, UMIN000009889. Registered on 28 January 2013.

Effects of immediate and delayed loading protocols on marginal bone loss around implants in unsplinted mandibular implant-retained overdentures: a systematic review and meta-analysis

BACKGROUND

Immediate loading has recently been introduced into unsplinted mandibular implant-retained overdentures for the management of edentulous patients due to their increasing demand on immediate aesthetics and function. However, there is still a scarcity of meta-analytical evidence on the efficacy of immediate loading compared to delayed loading in unsplinted mandibular implant-retained overdentures. The purpose of this study was to compare the marginal bone loss (MBL) around implants between immediate and delayed loading of unsplinted mandibular implant-retained overdentures.

METHODS

Randomized controlled trials (RCTs), controlled clinical trials (CCTs), and cohort studies quantitatively comparing the MBL around implants between immediate loading protocol (ILP) and delayed loading protocol (DLP) of unsplinted mandibular overdentures were included. A systematic search was carried out in PubMed, EMBASE, and CENTRAL databases on December 02, 2020. "Grey" literature was also searched. A meta-analysis was conducted to compare the pooled MBL of two different loading protocols of unsplinted mandibular overdentures through weighted mean differences (WMDs) with 95% confidence intervals (95% CIs). The subgroup analysis was performed between different attachment types (i.e. Locator attachment vs. ball anchor). The risk of bias within and across studies were assessed using the Cochrane Collaboration's tool, the Newcastle-Ottawa scale, and Egger's test.

RESULTS

Of 328 records, five RCTs and two cohort studies were included and evaluated, which totally contained 191 participants with 400 implants. The MBL of ILP group showed no significant difference with that of DLP group (WMD 0.04, CI - 0.13 to 0.21, P > .05). The subgroup analysis revealed similar results with Locator attachments or ball anchors (P > .05). Apart from one RCT (20%) with a high risk of bias, four RCTs (80%) showed a moderate risk of bias. Two prospective cohort studies were proved with acceptable quality. Seven included studies have reported 5.03% implant failure rate (10 of 199 implants) in ILP group and 1.00% failure rate (2 of 201 implants) in DLP group in total.

CONCLUSIONS

For unsplinted mandibular implant-retained overdentures, the MBL around implants after ILP seems comparable to that of implants after DLP. Immediate loading may be a promising alternative to delayed loading for the management of unsplinted mandibular implant-retained overdentures. PROSPERO registration number: CRD42020159124.

Effect of 2-implant mandibular overdenture with different attachments and loading protocols on peri-implant health and prosthetic complications: A systematic review and network meta-analysis

STATEMENT OF PROBLEM

A systematic review of the effect of different overdenture attachments with different loading protocols on peri-implant health is lacking.

PURPOSE

The purpose of this systematic review and network meta-analysis was to evaluate the effect of different overdenture attachments with delayed or immediately loaded 2-implant-retained mandibular overdentures on peri-implant tissue health.

MATERIAL AND METHODS

A comprehensive search of the PubMed, EMBASE, and Cochrane library was conducted to identify eligible randomized controlled trials (RCTs). The outcomes were marginal bone loss, probing depth, plaque index, bleeding on probing, implant survival rate, and prosthetic complications. The Bayesian network meta-analysis accompanied by a random effect model and 95% credible intervals was calculated.

RESULTS

Sixteen RCT (n=599 participants receiving 1198 dental implants) were included. Five common overdenture attachment systems with delayed or immediate loading were compared. The difference in marginal bone loss and probing depth was not statistically significant when comparing different overdenture attachments with different loading protocols. The rank probability test showed that bar+ immediate loading ranked highest (63.8%) in terms of marginal bone loss, whereas ball+ delayed loading (73.3%) ranked highest in terms of probing depth. The implant survival rate was 100% for the LOCATOR+ delayed loading, resilient telescopic+ delayed loading, and magnet+ immediate loading; however, bar+ delayed loading, ball+ delayed loading, magnet+ delayed loading, LOCATOR+ immediate loading, ball+ immediate loading, and bar+ immediate loading had survival rates of 99.1%, 98.8%, 96.0%, 94.7%, 93.1%, and 91.2%, respectively.

CONCLUSIONS

All types of overdenture attachment with immediate loading or delayed loading had a similar effect on peri-implant health. Bar+ immediate loading was associated with the least marginal bone loss, whereas ball+ delayed loading showed the least probing depth.

Immediate vs conventional loading of mandibular overdentures: A comprehensive systematic review and meta-analysis of randomized controlled trials

Clinicians treating overdenture patients need to know if immediate loading and conventional loading results in similar outcomes. This study aimed to perform a systematic literature search of studies comparing immediate and conventional loading of mandibular overdentures irrespective of the number of implants and conduct a meta-analysis of implant failure and marginal bone loss (MBL). A literature search of PubMed, ScienceDirect, Ovoid, Springer, and Google Scholar databases was performed for randomized controlled trials (RCTs) comparing immediate vs conventional loading of mandibular overdentures. The primary outcome was implant failure and the secondary outcome was marginal bine loss (MBL). A descriptive analysis was performed for other outcomes. Thirteen trials were included. Only one trial compared the immediate and delayed loading of single implant-supported overdenture. Seven trials used two implants, one trial used three implants while four trials used four implants. Meta-analysis indicated no statistically significant difference in implant failure and MBL between immediate and conventional loading of two-implant and four-implant supported overdentures. Descriptive analysis indicated no difference in peri-implant tissue indices, implant stability, and quality of life outcomes between the two loading protocols.There may be no difference in implant failure and MBL with immediate loading or conventional loading of two and four-implant supported mandibular overdentures. Literature review indicates that there may be no difference in peri-implant tissue indices, implant stability, and QoL outcomes between the two loading protocols. The overall quality of evidence is moderate. Further, adequately powered RCTs are required to strengthen the evidence.

Peri-implant mucosal response to implant-supported overdentures: A systematic review and meta-analysis

OBJECTIVES

To systematically review and evaluate the effects of different types of attachments, implant numbers and loading protocols on the peri-implant mucosa of implant-supported overdentures (ISODs).

BACKGROUND

The impact of peri-implant tissue health on the ISOD treatment outcome is unclear, and current evidence is inadequate on this aspect.

MATERIALS AND METHODS

A systematic literature search for randomised controlled trials or prospective studies was conducted in indexed databases from 1995 to April 2020. The focused question was as follows: How does the peri-implant mucosa respond to implant-supported or implant-tissue-supported complete overdentures based on different types of attachments, implant numbers, and loading protocols, in terms of clinical outcomes achieved [plaque index (PI), gingival index (GI), probing pocket depth (PD) and bleeding index (BI)]? A random- or fixed-effects model was applied to measure the significance of standardised mean differences (SMD) of PD between the groups.

RESULTS

Seventeen studies met the eligibility criteria. The SMD for PD between splinted/bar and unsplinted/stud attachments was 0.10 mm (95% CI: -0.27 to 0.47; P = .60) and between 2- and 4-implant groups was 0.15 mm (95% CI: -0.16 to 0.45; P = .34), which were not statistically significant. Significant difference (P = .003) was observed between immediate/early loading and delayed loading (SMD = 0.46 mm [95% CI: 0.16 to 0.75]).

CONCLUSIONS

Probing depth for the immediate loaded implants was significantly higher than for the delayed loading group. No attachment type, implant number or loading protocol seemed to have a clear advantage over the other, in terms of other peri-implant mucosal outcome measures.

Immediate or delayed loading protocols for two-implant mandibular overdentures: A systematic review and meta-analysis of randomized controlled trials

STATEMENT OF PROBLEM

The immediate loading protocol for 2-implant mandibular overdentures has been widely reported. Nevertheless, the clinical effects reported in different articles are quite different.

PURPOSE

The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to compare the clinical effects of immediate and delayed loading of 2-implant mandibular overdentures.

MATERIAL AND METHODS

The review followed the guidelines of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). PubMed, Cochrane Library, Web of Science, Embase, Scopus, ScienceDirect, CBM, CNKI, and Wan Fang databases were searched electronically for RCTs published before March 25, 2020. Two authors independently conducted literature screening, quality assessment, and data extraction. The outcomes of interest were implant failure rate, marginal bone loss (MBL), implant stability quotient (ISQ), periotest value (PTV), and patient satisfaction.

RESULTS

A total of 2498 unduplicated records were identified. After full-text analysis, 7 eligible RCTs were included. All studies were followed for at least 12 months, and the meta-analysis was based on this. The meta-analysis showed that the implant failure rate in the immediate group was higher than that in the delayed group, but there was no statistically significant difference (I²=0%; n=7; risk difference [RD]=0.03; 95% confidence interval [CI]=-0.01 to 0.08). The difference of MBL between immediate and delayed loading was not significant (I²=88%; n=6; mean difference [MD]=-0.04; 95% CI=-0.16 to 0.24). Because of the limited articles reporting on ISQ, PTV, and patient satisfaction, no quantitative analysis was conducted for these outcomes.

CONCLUSIONS

Although the implant failure rate was more likely to favor the delayed group, available evidence indicates no statistical difference in implant failure and marginal bone loss between immediate and delayed loading protocols.

Immediate and Conventional Loading of a Single Dental Implant Placed in the Esthetic Zone May Yield Comparable Clinical Outcomes

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Clinical Outcomes Following Immediate Loading of Single-Tooth Implants in the Esthetic Zone: A Systematic Review and Meta-Analysis. Cheng Q, Su YY, Wang X, Chen S. Int J Oral Maxillofac Implants. 2020;35(1):167-177.

SOURCE OF FUNDING

National Natural Science Foundation of China (grant no. 81570999).

TYPE OF STUDY/DESIGN

Systematic review and meta-analysis.

Immediate vs conventional loading of Facility-Equator system in mandibular overdenture wearers: 1-year RCT with clinical, biological, and functional evaluation

BACKGROUND

The use of immediate loading (IML) is still poorly explored in elderly patients and implant-retained mandibular overdenture (IMO) wearers. For this reason, more comparisons to conventional loading (CL) are required.

PURPOSE

To evaluate the clinical, biological, functional, and oral health-related quality of life (OHRQOL) influence of CL and IML loading on elders wearing IMO retained by the Facility-Equator system up to 1 year after implant installation.

MATERIAL AND METHODS

Twenty edentulous patients received two narrow diameter implants in the mandible; the loading type (CL or IML) was randomized. The clinical parameters were monitored along with prosthetic events, marginal bone loss (MBL) and bone level change (BLC), implant stability quotients (ISQ), masticatory performance outcomes, and Interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) levels in the peri-implant crevicular fluid during the first year of loading. The OHRQoL was assessed via the Oral Health Impact Profile-EDENT questionnaire. Data were analyzed by the Mann-Whitney, χ² , Wilcoxon paired, and McNemar tests.

RESULTS

After 1 year, MBL, BLC and ISQ were statistically identical (P > .05) in the CL and IML groups. The probing depth at 12 months in the CL group (2.19 mm) was higher than in the IML group (1.29 mm; P ≤ .0001). TNF-α was 33.6% higher in the CL group at 6 months (P = .043), while IL-1β was significantly higher in the IML group up to 6 months. The survival rate was 90% in the CL group and 85% in the IML group; 33 prosthetic events occurred in CL group and 23 in IML group.

CONCLUSIONS

After 12 months, both loading protocols are viable and result in similar clinical, biological, functional, and OHRQOL outcomes. However, IML generates better adaptation of the peri-implant tissues, faster improvement in OHRQoL and fewer prosthetic intercurrences than CL.

Peri-implant marginal bone loss rate pre- and post-loading: An exploratory analysis of associated factors

OBJECTIVES

To perform an exploratory analysis of factors influencing annual rates of peri-implant marginal bone loss (RBL) calculated over different time frames, at implants unaffected by peri-implantitis.

MATERIAL AND METHODS

A total of 154 implants from 86 patients were reviewed at 1.6-6.8 years after placement. Marginal bone levels (MBL) were assessed on intraoral radiographs at three time-points: immediately post-placement, time of loading, and least 1-year post-loading. RBLs (mm/year) were computed using these three time frames and corresponding MBL changes as: RBL placement-loading, RBL loading-review, RBL placement-review. Exploratory ordination of three RBLs, corresponding time durations, and 17 background factors were used for visualization. Hierarchical linear mixed-effects models (MEM) with predictor selection were applied to RBL outcomes. The correlation of actual MBL with MBLs predicted by RBL placement-loading and RBL loading-review was tested.

RESULTS

Median RBL placement-loading was 0.9 mm/year (IQR = 2.02), loading-review was 0.06 mm/year (IQR = 0.16), and overall RBL placement-review was 0.21 mm/year (IQR = 0.33). Among-patient variance was highest for RBL placement-loading (SD = 0.66). Longer time predicted lower RBL in all time frames. Shorter time of loading significantly predicted lower RBL placement-review. Augmentation predicted lower RBL placement-loading, while anterior location and older age predicted lower RBLs placement-loading placement-review. Only MBL projected using RBL placement-loading significantly correlated with actual MBL.

CONCLUSIONS

Exploratory analysis indicated RBL varied with the time duration used for calculation in pre- and post-loading, and overall periods. In each period, RBL declined with increasing time. Earlier loading predicted lower overall RBL. Higher pre-loading RBL predicted worse actual bone level.

Meta-analysis of randomized clinical trials comparing clinical and patient-reported outcomes between extra-short (≤6 mm) and longer (≥10 mm) implants

AIM

To compare the clinical outcomes of ≤6 mm extra-short implants (test group) versus ≥10 mm long implants (control group), with and without bone augmentation procedures.

MATERIALS AND METHODS

A systemic literature search of randomized clinical trials was performed using the PubMed (MEDLINE) and EMBASE databases. A quantitative meta-analysis was conducted to compare all the outcome variables. Meta-regression analysis determined the effect of bone augmentation procedures and the influence of other clinical covariates on the results.

RESULTS

Eighteen studies comprising 1,612 implants (793 extra-short and 820 long implants) were selected for the meta-analysis. No statistically significant difference in the survival rate was observed at 1 and 3 years (p > 0.05). Extra-short implants displayed less marginal bone loss (MBL) from both implant placement time points (1 and 3 years) and prosthetic placement (1 year), as well as less biological complications, surgical time and treatment cost (p < 0.05). Contrarily, a statistically significant small number of prosthetic complications were reported with long implants (p < 0.05).

CONCLUSIONS

Placement of extra-short implants (≤6 mm) presented as an equivalent option in the treatment of patients with an atrophic posterior arch up to 3-year follow-up. However, the long-term effectiveness of extra-short dental implants remains to be further studied.

Rehabilitation of the edentulous mandible with implant-supported overdentures on telescopic abutments and immediate loading. A controlled prospective clinical study

The rehabilitation of the edentulous mandible with implant-supported overdentures is an established clinical procedure but immediate loading of implants supporting mandibular overdentures has not been equally documented.

AIM

The aim of this prospective clinical study was to evaluate the rehabilitation of the edentulous mandible with immediate loading and implant-supported overdentures.

MATERIALS AND METHODS

10 patients were restored with immediate loading of the implants and 5 with delayed loading. The treatment planning included placement of four implants in the interforaminal area of the mandible. Prefabricated titanium abutments with 4 degrees of conical inclination were fixed on the implants and the telescoping conical caps were connected to the base of the mandibular denture. Bone loss was assessed by comparison of panoramic x-rays at baseline 3, 6, and 36 months by visual observation from clinicians.

RESULTS

A total of 60 implants were restored, 40 with immediate and 20 with delayed loading. The follow-up period ranged from 4 to 10 years with 72 months mean observation time. Prosthetic complications appeared with low frequency and no implant loss occurred during the follow-up period. No statistical significance was observed in the bone loss in the cervical area of the immediate and late loaded implants.

CLINICAL SIGNIFICANCE

The rehabilitation of the edentulous mandible with implant-supported overdentures and telescopic copings is a viable clinical solutions with multiple clinical advantages both for the clinician and the patient. . Immediate loading can be applied in cases where increased initial stability can be achieved. More extended long-term clinical studies with increased number of patients and implants are needed, however, to verify the efficacy of the treatment method.