Are implant-supported removable partial dentures a suitable treatment for partially edentulous patients? A systematic review and meta-analysis

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of select 2023 dental literature to briefly touch on several topics of interest to modern restorative dentistry. Each committee member brings discipline-specific expertize in their subject areas that include (in order of appearance here): prosthodontics; periodontics, alveolar bone, and peri-implant tissues; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine, oral and maxillofacial surgery, and oral radiology; and dental caries and cariology. The authors have focused their efforts on presenting information likely to influence the daily dental treatment decisions of the reader with an emphasis on current innovations, new materials and processes, emerging technology, and future trends in dentistry. With the overwhelming volume of literature published daily in dentistry and related disciplines, this review cannot be comprehensive. Instead, its purpose is to inform and update interested readers and provide valuable resource material for those willing to subsequently pursue greater detail on their own. Our intent remains to assist colleagues in navigating the tremendous volume of newly minted information produced annually. Finally, we hope readers find this work helpful in providing evidence-based care to patients seeking healthier and happier lives. (J Prosthet Dent 2024;132:■■■-■■■).

Impact of tilted implants for implant-supported fixed partial dentures: A systematic review with meta-analysis

STATEMENT OF PROBLEM

The use of tilted implants has been considered a suitable option for completely edentulous patients. However, consensus on their clinical performance is lacking, specifically for partial rehabilitation.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the marginal bone loss and implant survival rate of tilted implants compared with those of axial implants for implant-supported fixed partial dentures (ISFPDs).

MATERIAL AND METHODS

A systematic search of the MEDLINE/PubMed, Web of Science, Embase, Cochrane, and ProQuest databases and reference lists for articles published until May 2022 was performed by 2 independent reviewers without language or publication date restrictions. A meta-analysis was performed using the RevMan version 5.4 program. Quality assessments were performed using the Newcastle-Ottawa scale.

RESULTS

Nine studies were included, totaling 258 participants and 604 implants (269 tilted implants and 335 axial implants). No significant differences were found between the tilted and axial implants for the implant survival rate (P=.81; risk ratio: 1.14). However, higher marginal bone loss values were observed for tilted implants (P=.001; mean difference: 0.12 mm). No significant heterogeneity was observed in either analysis.

CONCLUSIONS

No significant relationship was found between tilted and axial implants for ISFPD rehabilitation. However, tilted implants presented greater risks of marginal bone loss than axial implants.

Effects of Loading Forces, Loading Positions, and Splinting of Two, Three, or Four Ti-Zr (Roxolid®) Mini-Implants Supporting the Mandibular Overdentures on Peri-Implant and Posterior Edentulous Area Strains

Clinical indications for the Ti-Zr alloy (Roxolid®) mini-implants (MDIs) in subjects with narrow ridges are still under review. The aim was to analyze peri-implant and posterior edentulous area strains dependent on the MDI number, splinting status, loading force, and loading position. Six models were digitally designed and printed. Two, three, or four Ti-Zr MDIs, splinted with a bar or unsplinted (single units), supported mandibular overdentures (ODs), loaded with 50-300 N forces unilaterally, bilaterally, and anteriorly. The artificial mucosa thickness was 2 mm. Strain gauges were bonded on the vestibular and oral peri-implant sides of each MDI, and on the posterior edentulous area under the ODs. Loadings were performed through the metal plate placed on ODs' artificial teeth (15 times repeated). Arithmetic means with standard deviations and the significance of the differences (MANOVA, Sheffe post hoc) were calculated. Different MDI numbers, loading positions, forces, and splinting elicited different peri-implant microstrains. In the two-MDI models, 300 N force during unilateral loading elicited the highest microstrains (almost 3000 εμ on the loaded side), which can jeopardize bone reparation. On the opposite side, >2500 εμ was registered, which represents high strains. During bilateral loadings, microstrains hardly exceeded 2000 εμ, indicating that bilateral chewers or subjects having lower forces can benefit from the two Ti-Zr MDIs, irrespective of splinting. However, in subjects chewing unilaterally, and inducing higher forces (natural teeth antagonists), or bruxers, only two MDIs may not be sufficient to support the OD. By increasing implant numbers, peri-implant strains decrease in both splinted and single-unit MDI models, far beyond values that can interfere with bone reparation, indicating that splinting is not necessary. When the positions of the loading forces are closer to the implant, higher peri-implant strains are induced. Regarding the distal edentulous area, microstrains reached 2000 εμ only during unilateral loadings in the two-MDI models, and all other strains were lower, below 1500 εμ, confirming that implant-supported overdentures do not lead to edentulous ridge atrophy.

Removable partial dentures assisted by short implants: A 34-month randomized controlled clinical trial

STATEMENT OF PROBLEM

Implant-assisted removable partial dentures (IARPDs) have been used to treat partially edentulous patients, yet limited information is available on the relationship between prosthetic complications and patient satisfaction as compared with conventional removable partial dentures (RPDs).

PURPOSE

The purpose of this randomized controlled clinical trial was to measure the satisfaction of patients who received either conventional or RPDs assisted by short implants and to assess and compare the incidence and type of prosthetic complications after a mean observational period of 34 months.

MATERIAL AND METHODS

Thirty-one healthy and bilaterally edentulous (Kennedy Class I) individuals who were seeking treatment and were candidates for posterior implant placement, were randomly allocated to either the conventional removable partial denture (CRPD) or the short implant-assisted removable partial denture (IARPD) groups. CRPDs following the same fabrication procedures were delivered to all participants irrespective of the group assignment,. One month after delivery, each participant from the IARPD group received 2 short implants. Upon osseointegration, the existing prostheses were converted to IARPDs with the use of LOCATOR attachments. The chi-squared test, log-rank test, and Mann-Whitney U test were used for statistical analysis (α=.05).

RESULTS

Data were collected from 31 participants: 18 in the CRPD and 13 in the IARPD group. The results showed that prosthetic complications occurred in both CRPD and IARPD groups. The chi-squared test showed no statistically significant difference between the 2 groups with regard to the incidence of prosthetic complications (P=.474). The log-rank test used for survival rate and complications showed no statistically significant difference between the 2 groups (P=.903). The Mann-Whitney U test showed no statistically significant difference in patient satisfaction between the 2 groups (P=.938).

CONCLUSIONS

No statistically significant difference in the incidence and type of prosthetic complications was observed between conventional and RPDs assisted by short implants after a mean observation period of 34 months.

Effect of surgical and prosthodontic protocols of distal extension implant-supported removable partial dentures on clinical and patient-reported outcomes: A systematic review

STATEMENT OF PROBLEM

Standard surgical and prosthodontic protocols for managing partially dentate patients with implant-supported removable partial dentures (ISRPDs) are lacking.

PURPOSE

The purpose of this systematic review was to determine clinical and patient-reported outcome measures (PROMs) in patients provided with ISRPDs in distal edentulous arches based on different surgical and prosthodontic protocols.

MATERIAL AND METHODS

An electronic and manual literature search was conducted in 3 databases, PubMed/MEDLINE, SCOPUS, and Cochrane Library, for clinical studies on distal extension ISRPDs related to clinical and patient-reported outcomes. Kennedy Class I and II arches described in articles published from January 2000 to December 2023 were included. Clinical parameters regarding implant type, location, loading protocols, and implant survival rate and PROMs including masticatory performance, esthetics, and overall satisfaction were compared. The risk of bias was determined by using the Cochrane Risk of Bias Tool 2.0 (RoB 2.0).

RESULTS

An initial total of 103 studies were identified, but only 11 articles were selected after implementing the inclusion and exclusion criteria. Ten studies evaluated PROMs, and 6 studies evaluated clinical outcomes (5 studies evaluated both). The implant survival rate ranged from 91.7% to 100%, with no clear differentiation among the studies with immediate or delayed loading protocols. Most studies described implants positioned in the molar region. In general, patient satisfaction and oral health-related quality of life (OHRQoL) improved significantly with ISRPDs compared with conventional removable partial dentures (RPDs) or RPDs with healing abutments. Posttreatment clinical outcomes revealed stable peri-implant health with no significant bone loss or prosthetic complications. No specific implant configuration, including implant type and location or attachment system, appeared to be better than another. Ball attachments were the commonly used attachments. Two studies were of high risk and 3 studies of low risk. The remaining 6 studies were judged to have some concerns based on the RoB 2.0 analysis.

CONCLUSIONS

Providing an ISRPD improved patient satisfaction, OHRQoL, and the clinical outcomes in distal extension situations, with most studies positioning the implants in the molar region. The type of attachment did not significantly affect the outcomes, although ball attachments were the most used attachment in ISRPDs.

Implant-assisted removable partial dentures: Part II. a systematic review of the effects of implant position on the biomechanical behavior

PURPOSE

This systematic review aimed to evaluate the effects of implant placement sites on the biomechanical behavior of implant-assisted removable partial dentures (IARPDs) using finite element analysis (FEA).

STUDY SELECTION

Two reviewers independently conducted manual searches of the PubMed, Scopus, and ProQuest databases for articles investigating implant location in IARPDs using FEA, according to the 2020 Systematic Reviews and Meta-analyses statement. Studies published in English up to August 1, 2022, were included in the analysis based on the critical question.

RESULTS

Seven articles meeting the inclusion criteria were systematically reviewed. Six studies investigated mandibular Kennedy Class I and one study investigated mandibular Kennedy Class II. Implant placement reduced the displacement and stress distribution of the IARPD components, including dental implants and abutment teeth, regardless of the Kennedy Class type and dental implant placement site. Most of the included studies showed that, based on the biomechanical behavior, the molar region, rather than the premolar region, is the preferred implant placement site. None of the selected studies investigated the maxillary Kennedy Class I and II.

CONCLUSIONS

Based on the FEA regarding mandibular IARPDs, we concluded that implant placement in both the premolar and molar regions improves the biomechanical behaviors of IARPD components, regardless of the Kennedy Class. Implant placement in the molar region results in more suitable biomechanical behaviors compared with implant placement in the premolar region in Kennedy Class I. No conclusion was reached for Kennedy Class II due to the lack of relevant studies.

Implant-assisted removable partial dentures: Part I. a scoping review of clinical applications

PURPOSE

This scoping review aimed to systematically map research regarding implant-assisted removable partial dentures (IARPDs), and identify existing gaps in knowledge.

STUDY SELECTION

Two reviewers independently conducted a search of the MEDLINE-PubMed and Scopus databases according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) extension for Scoping Review and included articles published in English up to August 31, 2022, including human studies, reviews, and in vitro studies. Expert opinions, animal studies, and clinical studies involving complete overdentures were excluded, and ten aspects for establishing the treatment strategy for IARPDs were examined.

RESULTS

One hundred and twelve articles were chosen. There were two treatment modalities: IARPDs retained by implant- and tooth-supported surveyed single crowns (SCs) or fixed partial dentures (FPDs). In IARPDs retained by tooth-supported surveyed SCs or FPDs, the survival rate of dental implants for IARPDs was relatively higher with a wide range of marginal bone loss and many complications, but with improved functional performance, oral health-related quality of life, and patient satisfaction. There were limited data on survival or success rates and designs of IARPDs, attachment selections, length and diameter, inclination, placement sites, and loading protocols of implants, regardless of prosthetic types. There was limited information on maxillary IARPDs except for survival rates of implants.

CONCLUSIONS

Although IARPDs could become a useful treatment strategy, there is limited scientific consensus with gaps in knowledge about their use. Additional well-designed clinical and in vitro studies are necessary to scientifically establish IARPDs as definitive prostheses in implant dentistry.

Mini-Implants Retaining Removable Partial Dentures in Subjects without Posterior Teeth: A 5-Year Prospective Study Comparing the Maxilla and the Mandible

Background and objectives: Long-term studies of clinical outcomes of mini-implants (MDIs) in the first premolar/canine sites retaining a bilateral free-ending removable partial dentures (RPD) in Kennedy class I subjects have not been well documented. The aim was to assess clinical outcomes in a prospective 5-year cohort study comparing the mandible and maxilla. Material and Methods: Participants (n = 92) who received two MDIs each and a new RPD were reviewed after one, three and five years. A total of 71 participants (82 mini-implants in the mandible; 58 in the maxilla) completed the study. Marginal bone level change, success, survival rates, Modified Plaque (MPI) and Bleeding Indices (MBI) were assessed. Results: The five-year success rate was 93.3% and 93.4% (p > 0.05), in the mandible and the maxilla, respectively. Mean peri-implant bone loss (MBL) increased significantly over five years (p < 0.01) to 0.50 mm in the mandible and 0.52 mm in the maxilla. Age had a significant effect on the MBL (higher rates in younger participants), while jaw of insertion, gender, and antagonistic jaw status did not. MPI and MBI were not significantly correlated with MBL. Conclusions: The insertion of two MDIs in previous first premolar/canine sites for retention of a free-end saddle RPD can be a successful treatment modality in subjects with narrow alveolar ridges.

Safety Evaluation of Oral Sirolimus in the Treatment of Childhood Diseases: A Systematic Review

Background: Sirolimus, a mammalian target of rapamycin inhibitor, has been widely used in pediatric patients, but the safety of sirolimus in pediatric patients has not been well determined. Objective: The objective of this study was to systematically evaluate prospective studies reporting the safety of sirolimus in the treatment of childhood diseases. Methods: The following data were extracted in a standardized manner: study design, demographic characteristics, intervention, and safety outcomes. Results: In total, 9 studies were included, encompassing 575 patients who received oral sirolimus for at least 6 months. Various adverse events occurred. The most common adverse event was oral mucositis (8.2%, 95% CI: 0.054 to 0.110). Through comparative analysis of the subgroups based on the targeted concentration range, we discovered that many adverse events were significantly higher in the high concentration group (≥10 ng/mL) than in the low concentration group (<10 ng/mL) (p < 0.01). More interestingly, we found that oral mucositis was more frequently reported in children with vascular anomalies than tuberous sclerosis complex. Conclusions: This study shows that oral sirolimus in the treatment of childhood diseases is safe and reliable. However, sirolimus treatment in the pediatric population should be strictly monitored to reduce the occurrence of serious or fatal adverse events.

Dental Implant Treatment in Patients Suffering from Oral Lichen Planus: A Narrative Review

BACKGROUND

The aim of this study was to describe the complications and survival rates of dental implants placed in patients suffering from oral lichen planus (OLP) and to present recommendations for implant treatment in this group of patients through a narrative review of the published studies.

METHODS

A search of the literature was conducted using four databases: PubMed/Medline, Web of Science, Cochrane, and Scopus with a stop date of May 2022.

RESULTS

Eighteen studies were evaluated. The results showed that dental implant survival rates in patients with OLP were similar to those reported in the general population. Moreover, the existing literature seemed to imply that OLP is not a suspected risk factor for peri-implant diseases. However, patients suffering from erosive forms of OLP or desquamative gingivitis and poor oral hygiene were more susceptible to developing peri-implant diseases; in addition, oral squamous cell carcinoma was observed in a few cases of OLP.

CONCLUSION

With the limitations of this narrative review, dental implants may be regarded as a safe and feasible therapeutic approach to the treatment of patients with well-controlled OLP. These patients should be monitored carefully during follow-up care. Well-designed prospective trials are required to validate the present findings.

Insufficient Evidence to Ascertain the Long-Term Survival of PEEK Dental Prostheses: A Systematic Review of Clinical Studies

Introduction: Polyetheretherketone (PEEK) is a polymer that is used in the construction of orthopaedic and dental implants. It is also used to construct removable and fixed dental prostheses due to its superior mechanical and esthetic properties compared to conventional materials. This systematic review aims to analyse and appraise the literature concerning PEEK dental prostheses critically. Methods: The following focused question was constructed ‘Are dental prostheses made of PEEK inferior to those made of other materials in terms of clinical- and patient-reported outcomes?’. The CONSORT (Consolidated Standards of Reporting Trials) tool was used for the quality assessment of the randomised clinical trials. The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) quality assessment tool was used to assess the quality of observational studies and the case reports were evaluated using the CARE (Case Report) guidelines. Results: A total of 12 studies were included in this review. Two case studies received an overall grade of medium and the overall quality of six studies was graded as ‘low’. All three observational studies and the only randomised controlled trial received scores of ‘medium’. Conclusion: PEEK-based dental prostheses may provide a viable and more esthetic alternative to conventional prosthodontic appliances. However, within the limitations of this study is the evidence to ascertain the long-term viability of PEEK-based dental prostheses. Future studies should focus on conducting large-scale, multicenter trials to compare the survival rate of PEEK prostheses to that of conventionally available prosthodontic appliances.