CADTH Health Technology Review

Longevity of Partial and Complete Dentures

Rapid Review

Authors: Sara D. Khangura, Aleksandra Grobelna, Robyn Haas, Anusree Subramonian

Key Messages

• Removable complete dentures may last for an average of 10.06 years, with most complete dentures lasting for at least 5 years.

• Most metal partial dentures may last for at least 5 years.

• We did not identify any studies that met inclusion criteria for our report describing the longevity of removable plastic partial dentures.

• The included studies did not report populations, interventions, and outcomes clearly or consistently. This made some of the findings difficult to interpret.

Context and Policy Issues

Tooth loss is a problem that can affect people of all ages, although it is often associated with advanced age.¹ Tooth loss can be partial or complete (also known as edentulism) and can impede speaking and eating, causing deleterious effects to the activities of daily life.^2,3 In addition, tooth loss can affect aesthetics, which can negatively affect quality of life.¹ Tooth loss may also be associated with a variety of comorbidities, including malnutrition, heart disease, and osteoporosis.⁴

Although decreasing incidence of tooth loss has been observed among industrialized countries in the past several decades, aging populations in these countries continue to drive the need for treatment.⁵ As the proportion of Canada’s population with advanced age increases, estimates indicate that the need for dental care to treat tooth loss will similarly increase.¹

Tooth loss can be treated in a variety of ways depending on the extent of loss and other factors. Possible treatment options include fixed prostheses, such as implants and dental bridges, or removable dental prostheses, such as complete or partial dentures.^6,7 Removable dentures are designed to be supported by the surrounding soft and/or hard tissues of the oral cavity or may be supported by dental implants.⁸ Removable dentures can be made of various materials, including metals or plastics, such as cast alloy or acrylic.⁹ Removable dentures offer the benefits of being minimally invasive and a less costly treatment option compared with fixed dental prostheses.^4,10 Affordability can be an important feature of dental care interventions, which are not often covered by public health plans in Canada.¹¹ Some of the potential disadvantages of removable dentures include the need for regular removal and cleaning, which can make dentures susceptible to wear and/or damage and can impact longevity.^7,12

A previous CADTH report was published in 2015 that identified available evidence describing the longevity of removable prosthodontics.¹³ In that report, there was high variability in the findings of the included studies; therefore, the need for robust clinical evidence to support informed decision-making about the use of dentures was identified.¹³ This report aims to update and summarize the available evidence on the longevity of removable dentures that has been published since the previous 2015 CADTH report.¹³

Research Questions

1. What is the clinical evidence on the longevity of removable complete dentures?

2. What is the clinical evidence on the longevity of removable plastic partial dentures?

3. What is the clinical evidence on the longevity of removable metal partial dentures?

Methods

Literature Search Methods

A limited literature search was conducted by an information specialist on key resources including MEDLINE, the Cochrane Database of Systematic Reviews, the International HTA Database, the websites of Canadian and major international health technology agencies, as well as a focused internet search. The search strategy comprised both controlled vocabulary, such as the National Library of Medicine’s MeSH (Medical Subject Headings), and keywords. The main search concepts were longevity of complete and partial dentures. CADTH-developed search filters were applied to limit retrieval to health technology assessments, systematic reviews (SRs), meta-analyses, or indirect treatment comparisons and randomized controlled trials, controlled clinical trials, or any other type of clinical trial. If possible, retrieval was limited to the human population. The search was completed on January 24, 2023, and limited to English-language documents published since January 1, 2015.

Selection Criteria and Methods

One reviewer screened citations and selected studies. In the first level of screening, titles and abstracts were reviewed and potentially relevant articles were retrieved and assessed for inclusion. With the aim of updating the evidence presented in a previous CADTH report published in 2015,¹³ articles were included if they were published after the previous search date and were not included in the earlier CADTH report. The final selection of full-text articles was based on the inclusion criteria presented in Table 1.

Exclusion Criteria

Articles were excluded if they did not meet the selection criteria outlined in Table 1, were duplicate publications, or were published before 2015. SRs in which all relevant studies were captured in other more recent or more comprehensive SRs were excluded.

Critical Appraisal of Individual Studies

The included SRs were critically appraised by 1 reviewer using the AMSTAR (A Measurement Tool to Assess Systematic Reviews 2) tool.¹⁴ Summary scores were not calculated for the included SRs; rather, the strengths and limitations observed among the included SRs were summarized and described narratively.

Summary of Evidence

Quantity of Research Available

A total of 730 citations were identified in the literature search. Following screening of titles and abstracts, 669 citations were excluded and 61 potentially relevant reports from the electronic search were retrieved for full-text review. Two potentially relevant publications were retrieved from the grey literature search for full-text review. Of these potentially relevant articles, 55 publications were excluded for various reasons, and 8 SRs met the eligibility criteria for inclusion in this report. Appendix 1 presents the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses)¹⁵ flow chart that outlines study selection.

Additional references of potential interest are provided in Appendix 5.

Summary of Study Characteristics

Eight SRs were included and summarized in this report.^16-23 Seven^16,17,19-23 of the 8 SRs had inclusion criteria that were broader than the current review. Specifically, these SRs reported results from included primary studies on outcomes other than those relevant to longevity,^16,17,19-23 and 1 SR also did not specify the material from which the removable partial dentures were constructed for some of the included primary studies.²² Only the characteristics and results for the subset of relevant primary studies in the included SRs were described in this report.

Additional details regarding the characteristics of included publications are provided in Appendix 2.

Study Design

The 8 SRs were published between 2016 and 2022, with search strategies that spanned publication dates from 1919 to April 2022.^16-23 There were 114 primary studies of relevance to this review included in the 8 eligible SRs, spanning publication dates between 1967 and 2020.^16-23 Overlap between the primary studies of relevance described in the SRs included in this report was minimal (i.e., 1 of 114 primary studies overlapped across 2 included SRs^17,19); thus, a tabulated characterization of overlap was not included.

Details describing the designs of primary studies included in the SRs were not reported, but primary study designs, as referred to in the SRs, included randomized controlled trials and prospective and retrospective clinical studies.^16-23

Country of Origin

Of the 8 SRs, first authors were based in Saudi Arabia,¹⁶ the UK,¹⁷ Australia,¹⁸ the Republic of Korea,¹⁹ Brazil,^20,21 Germany,²² and the US.²³ Five of the SRs did not report the country of origin for included primary studies,^16,19-21,23 whereas 3 reported primary studies from multiple countries throughout the world,^17,18,22 including 1 that reported the inclusion of relevant primary studies from Canada.¹⁸

Patient Population

Of the 5 SRs that clearly reported the number of study patients included in all relevant primary studies, the range of patients with eligible outcome data reported across SRs was between 15 and 1,656.^{16,17,19,20,23} Two of the SRs reported the numbers of patients observed for some, but not all, of the relevant primary studies.^21,22 One SR reported numbers for “sample size” for each included primary study in a table that included data on both patients and dentures; thus, it was unclear whether these data were specific to patients or dentures.¹⁸

There were few details included describing the patient study populations, with most SRs indicating that they sought and included studies investigating dental patients with edentulism and/or those with partial tooth loss.^16-23 Five SRs reported data describing mean age for included primary studies, which ranged among the relevant primary studies from 59.5 years to 71.1 years.^16-18,20,21 Two of the SRs included information describing sex, with 1 indicating that 58.2% of the patients from the primary studies included in the SR were female,¹⁸ and another describing 318 females and 311 males among the patient study populations included in relevant primary studies.²⁰ No information was reported on socioeconomic or other demographic variables.

Interventions and Comparators

Six of the SRs described complete removable dentures,^{16-18,20,21,23} and 2 described partial removable dentures.^19,22 The type and design of dentures as described in the SRs were interpreted as reported by the authors of the publications (i.e., SRs describing dentures as complete or full-arch were included as complete dentures; dentures described as partial dentures were included as partial removable dentures).

Of the 6 SRs describing complete removable dentures, 2 SRs reported the total number of dentures observed across the relevant primary studies,^16,18 which ranged between 15 and 3,023 dentures; the other SRs describing complete removable dentures did not include or report the numbers of dentures observed across some or all the relevant primary studies.^17,20,21,23 Dentures were described as complete dentures by 1 SR,¹⁸ complete overdentures by 1 SR,²¹ maxillary overdentures by 2 SRs,^16,23 and full-arch dentures by 2 SRs.^17,20 The material that the dentures were constructed of was specified in 1 SR as polyetheretherketone (PEEK),¹⁶ but it was not described in the other 5 SRs.^{17,18,20,21,23} Five SRs described complete dentures that were supported by implants^{16,17,20,21,23} — 1 of which also described complete dentures that were supported by teeth¹⁷ — and 1 SR did not specify the mechanism(s) of attachment.¹⁸

Both SRs on partial removable dentures described dentures constructed of metal.^19,22 One SR reported relevant data on 394 implant-supported removable dentures²² and the other reported relevant data on 1,587 dentures (with attachment mechanisms not consistently described).¹⁹

Although comparators were described by some SRs for some primary studies, these data were not reported consistently, with no relevant comparative data on denture longevity reported by any of the included SRs.^16-23

Outcomes

All SRs included in this report described outcomes of relevance to longevity.^16-23 Specifically, 2 of the included SRs reported data on the mean number of years that dentures survived,^18,22 5 of the included SRs reported data on the numbers and/or proportions of dentures that failed across study follow-up,^16,18,20-22 and 5 of the SRs reported on the numbers and/or proportion of dentures that survived across study follow-up.^{17,19,20,22,23} The durations of study follow-up for relevant primary studies across the 8 SRs included in this review ranged between 1 and 25 years.^16-23

Definitions of survival and/or failure were not provided for 6 of the included SRs.^16,18,20-23 Of the 2 SRs that defined prosthesis survival, 1 described it as the prosthesis remaining in situ and not requiring replacement at a follow-up clinical examination.¹⁷ Another SR described survival as dentures that required only repair and could remain in service, whereas failure was defined as dentures that required refabrication.¹⁹

Six of the SRs summarized findings from relevant primary studies narratively, with no pooled results included,^{16,17,19,21-23} whereas 2 of the SRs reported findings both from individual relevant primary studies as well as pooled findings from across relevant primary studies.^18,20

Summary of Critical Appraisal

The SRs included in this review demonstrated both strengths and limitations.^16-23 Strengths common to all the SRs included a clear description of the research questions being posed, as well as key criteria informing study selection.^16-23 A review protocol was produced a priori for 5 of the included SRs.^16-18,20,21 Six of the SRs described methods satisfying the requirements of a comprehensive search strategy,^16-18,20-22 which is a key feature of SR methods that can increase confidence that the review has captured a sufficient breadth of available, eligible literature. Study selection methods were robust for 6 SRs with duplicate screening performed;^17-22 duplicate data abstraction was done for 5 of the SRs.^16-18,20,21 Study exclusions were clearly described for 5 of the SRs,^16,17,19-21 and risk of bias assessments for the included primary studies were described for 5 SRs.^16-18,20,21 Of the 2 SRs that reported on quantitative syntheses of data, both reported the use of appropriate methods for pooling data^18,20 and 1 was explicit about the potential impact of risk of bias on the findings generated by the meta-analyses (i.e., sensitivity analyses were conducted to elucidate the extent to which risk of bias may have affected the findings, demonstrating no change to the results).¹⁸ Finally, 5 of the SRs also were explicit about sources of funding and any conflicts of interest that could affect the conduct and/or findings of the reviews,^16,17,20-22 with 1 SR reporting a source of funding but providing no information on potential conflicts of interest.¹⁸ Providing this information is essential to ensure transparency and allow an assessment of the potential for undue external influence on the reviews.

Although 1 SR satisfied all the relevant criteria of the AMSTAR assessment,¹⁷ multiple limitations across the remaining 7 SRs were observed.^16,18-23 Clarity in reporting was limited; important details describing the populations, interventions, and outcomes summarized in the included SRs were missing, making interpretation of the methods and findings challenging.^16-23 An important inconsistency was observed in the 1 relevant primary study that overlapped between 2 of the included SRs: 1 SR described full-arch dentures¹⁷ and the other described removable partial dentures.¹⁹ A review of the relevant primary study that overlapped these 2 SRs was explicit in describing patients with edentulism, which suggests that the dentures under investigation in this primary study were complete dentures.²⁴ Because it concerns the particular SRs included in this review,^17,19 as well as the broader implications concerning terminology and definitions for the literature on removable dentures in general, this discrepancy indicates the potential for a critical lack of clarity in reporting and definitions which poses a threat to the interpretability and utility of the evidence in this topic area. Six of the SRs did not provide a clear justification for their inclusion criteria related to study design and did not explicitly account for risk of bias in the interpretation of the findings.^{16,18-20,22,23} Four of the SRs did not provide a clear or comprehensive description of potential reasons for heterogeneity in findings across primary studies (e.g., the variability among methods and interventions used).^16,19-21 Of the 2 SRs that performed quantitative syntheses of data, neither included a comprehensive consideration of publication bias and its potential impact on the pooled findings of the reviews.^18,20 Finally, 7 of the included SRs did not report sources of funding for included primary studies.^16,18-23 These missing details and methodological features make it difficult for the reader to assess the extent to which the findings of the SRs are reliable and/or valid; for instance, a clear and explicit strategy informing the selection of studies by design is essential to informing an interpretation of the extent to which the included primary studies in an SR can answer the research question being posed.¹⁴ In the case of publication bias (i.e., the propensity for studies with null findings to go unpublished), it is essential that this risk is assessed carefully and that any identification of this risk is considered in the context of the findings generated by the SR.¹⁴ Sources of funding for included primary studies are important for understanding the extent to which these may have introduced a risk of bias in the findings of the studies and the interpretation of their results (i.e., studies funded by private industry bear a greater risk of bias in favour of the intervention under study).¹⁴

A tabulated summary of the strengths and limitations of included SRs are provided in Appendix 3.

Summary of Findings

Longevity of Complete Dentures

Duration of Denture Survival

One SR reported duration of survival for complete dentures; pooled findings across 27 studies representing a total of 3,023 dentures found a weighted mean survival time of 10.06 years (standard deviation [SD] = 4.03 years).¹⁸ The range of mean years of survival for all complete denture types across the 27 relevant primary studies was 4.5 to 20 years.¹⁸ Subgroup analyses included those limited to maxillary dentures (n = 589), producing a weighted mean survival time of 10.26 years (SD = 3.80 years); mandibular dentures (n = 864 years), producing a weighted mean survival time of 8.63 years (SD = 2.63 years); and pairs of maxillary and mandibular dentures (n = 1,570), generating a weighted mean survival time of 10.76 years (SD = 4.68 years).¹⁸ Authors reported no statistical difference between types of dentures when mean years of survival were compared by independent t tests.¹⁸

Survival Rates of Dentures Across Study Follow-Up

Three SRs reported on survival of complete dentures across study follow-up.^17,20,23 Two of these SRs reported survival results from 22 primary studies with less than 5 years of follow-up, with rates ranging between 62% and 100%.^17,23 All 3 SRs reported on complete denture survival at 5 years of follow-up or more across 26 relevant primary studies, with rates ranging from 38% to 100%.^17,20,23

Failure Rates of Dentures Across Study Follow-Up

Four SRs reported on the failure of complete dentures across study follow-up;^16,18,20,21 2 reported findings from individual relevant primary studies only,^16,21 1 reported only pooled findings from across relevant primary studies,²⁰ and 1 reported both pooled findings across relevant primary studies as well as findings from individual, relevant primary studies.¹⁸ One of the SRs described the majority of its results in terms of survival; its pooled findings for survival were interpreted as failure rates in this report based on reporting of weighted event rates (with “events” more likely to pertain to failure) and inconsistencies observed between the event rates that were pooled and the survival results that were reported from individual, relevant primary studies.²⁰

One of the SRs pooled findings across 17 studies representing follow-up from 1 to more than 10 years, reporting that 21% (95% CI, 15% to 28%) of dentures failed by the end of follow-up.¹⁸ Subgroup analyses of failure rates by number of years of study follow-up were also performed. Findings from 3 relevant primary studies reporting on 1 to 2 years of study follow-up produced a pooled failure rate of 5% (95% CI, 0% to 10%) among maxillary and mandibular pairs of dentures.¹⁸ Findings from 7 relevant primary studies describing unpaired maxillary and mandibular dentures that reported on 5 to 6 years of follow-up generated a pooled failure rate of 12% (95% CI, 8% to 16%).¹⁸ Findings from 7 relevant primary studies describing failure of paired and unpaired maxillary and mandibular dentures at a study follow-up of more than 10 years produced a pooled rate of 41% (95% CI, 28% to 53%).¹⁸

Another SR with pooled findings reported weighted event rates of failure across studies with durations of study follow-up of 5 years or more for implant-supported full-arch dentures with either fewer than 5 implants, or 5 or more implants per denture.²⁰ Across 6 studies of dentures with fewer than 5 implants, the pooled weighted event rate of failure was reported at 1.5% (95% CI, 0.6% to 3.7%).²⁰ The pooled, weighted event rate of failure across 5 studies of full-arch dentures with 5 implants or more was 9% (95% CI, 5% to 15.38%).²⁰

Ranges of failure rates across 2 of the SRs that reported rates for relevant, individual primary studies varied widely.^16,18 There were a total of 6 relevant primary studies across the 2 SRs (3 of which provided results that were also included in meta-analyses¹⁸) that described complete denture failure as before 5 years of follow-up, with rates ranging between 0% and 20%.^16,18 In 1 of the SRs, 10 relevant primary studies reported follow-up of 5 to less than 20 years and reported ranges of failure rates between 0% and 79.2%.¹⁸ The same SR also included 2 relevant primary studies that reported on follow-up up of more than 20 years, and found failure rates of 23.5% and 50%.¹⁸ The remaining SR reported absolute numbers of failed dentures without clear denominators (i.e., denominators were reported as numbers of patients, and it is unclear whether these correlate precisely with the numbers of dentures observed in the studies).²¹ Due to this lack of clarity, no further narrative summary was provided.

Longevity of Plastic Partial Dentures

We did not identify any studies that reported findings for partial dentures that were explicitly described as being constructed of plastic materials.

Longevity of Metal Partial Dentures

Duration of Denture Survival

One SR reported that 33 removable, partial metal dentures from 1 relevant primary study (published in 1982) survived a mean number of 8 years (SD not reported).²²

Survival Rates of Dentures Across Study Follow-Up

Two SRs reported numbers and/or proportions of partial metal dentures that survived across study follow-up for 20 relevant primary studies.^19,22 Across the 2 SRs, 5 relevant primary studies reported on survival throughout study follow-up of less than 5 years, with proportions ranging from 93.3% to 100%.^19,22 Across the 2 SRs, 15 relevant primary studies reported on survival throughout study follow-up of 5 years or more, with proportions ranging from 13 of 33 dentures observed to 100%.^19,22

Failure Rates of Dentures Across Study Follow-Up

One SR reported numbers and/or proportions of partial metal dentures that failed across study follow-up among 4 relevant primary studies.²² Of 3 relevant primary studies that reported on failure across study follow-up of less than 5 years, 2 found failure rates of 3.2% and 3.8%, with 1 relevant primary study that reported 2 dentures failed from an unclear subgroup of a total 60 dentures observed in the study.²² The same SR also reported failure at 5 years or more of follow-up from 3 relevant primary studies that reported ranges between 2 of 26 dentures observed and 15 of 30 dentures observed.²²

Appendix 4 presents the main study findings.

Limitations

This review was limited in its capacity to summarize relevant data describing the longevity of removable dentures due to a lack of detail about the type of dentures being investigated (e.g., fixed versus removable, complete versus partial, and the material from which dentures were constructed). Of the literature that clearly described removable dentures, many studies reported on the longevity of implants used to support the prostheses, with no (or limited) data provided on the longevity of the prostheses themselves.

Similarly, of the studies identified reporting on the longevity of removable partial dentures, many were not explicit about the material from which the partial dentures were constructed, precluding their inclusion in this review because its focus was on research questions specific to metal or plastic partial dentures. The lack of clear reporting identified in the literature contributed to a key limitation of this review, namely the lack of any eligible SRs explicitly describing the longevity of removable partial dentures constructed of plastic materials. Related to this, there were 2 SRs identified that clearly described removable partial dentures constructed of metal, and both demonstrated important risks of bias as well as limited available data.^19,22

Lack of clarity was also observed in the variable use of terminology among the SRs included in this review that described complete dentures. Complete dentures were described as “complete dentures” by 1 SR,¹⁸ “complete overdentures” by 1 SR,²¹ “maxillary overdentures” by 2 SRs^16,23 and “full-arch dentures” by 2 SRs.^17,20 This variable terminology and consequent lack of clarity made ascertainment of the features of interventions under study unclear; for instance, the only 2 SRs which demonstrated any overlap (across 3 relevant primary studies) described the interventions in the same studies as “full-arch dentures”¹⁷ and “removable partial dentures,”¹⁹ respectively. This suggests that the terminology and/or eligibility criteria applied to primary studies was sufficiently unclear to be potentially inconsistent across SRs.

One limitation of the outcome data on longevity identified in this report was the potential for reliance on patient memory when measuring longevity in primary studies, which was explicitly acknowledged in 1 of the SRs.¹⁸ This method is limited in its accuracy, so it could affect the reliability and/or validity of SRs that include primary studies using it. Although the method of measurement for longevity was not clearly described in 5 other SRs included in this report,^19-23 this potential methodological limitation should be considered. Another limitation of the outcome data on longevity was the preponderance of data describing survival at a given length of follow-up as opposed to an open-ended duration of survival or time to failure (i.e., this presentation of longevity limits this report’s ability to provide specific insight into the anticipated time to replacement for complete and partial dentures).

Although the 8 SRs summarized in this report demonstrated both strengths and limitations in their methods,^16-23 4 of the SRs identified important methodological limitations in the primary research evidence they summarized,^16,17,20,21 indicating that risk of bias among the primary research is likely to be present and could affect the reliability and/or validity of the evidence informing the longevity of complete and partial dentures. Importantly, 3 of the SRs did not report an assessment of risk of bias for included primary studies (2 of which were the only SRs included in this review describing partial removable dentures), which represents a considerable limitation of these SRs.^19,22,23

Finally, there was very limited overlap identified among the relevant primary studies summarized in the SRs included in this report; there was also no overlap among the SRs included in this report and the primary studies identified as references of potential interest. This further corroborates the suggestion that there appears to be a large body of literature describing this topic that is — as discussed previously — variable in its focuses of interest (e.g., populations, interventions, and study outcomes), methods, and quality, which limits the extent to which it can be effectively interpreted and synthesized.

Conclusions and Implications for Decision- or Policy-Making

This review identified 8 SRs that reported clinical evidence describing the longevity of complete or partial removable dentures and were eligible for inclusion.^16-23

As was observed in the 2015 CADTH report,¹³ variable findings about the longevity of complete and partial removable dentures were found, with 1 SR that reported a pooled weighted mean of 10.06 years of survival for complete dentures¹⁸ and another that reported a mean of 8 years of survival for metal partial dentures (based on data from 1 primary study).²² Rates of survival ranged between 38% and 100% across study follow-up ranges between 1 and 20 years or more for complete dentures.^17,20,23 Rates of survival ranged between 48% and 100% across study follow-up ranges between 1 and 20 years or more for partial dentures constructed of metal.^19,22 Rates of failure for complete dentures ranged between 0% and 79.2% across study follow-up ranges between 1 and 20 years or more.^16,18,20,21 Rates of failure for partial metal dentures were 3.8% and 3.2% at 2 and 4 years of study follow-up, respectively.²²

These variable findings may reflect considerable differences across the SRs included in this review, and the relevant primary studies that they summarize regarding intervention (i.e., various types of dentures) and study objectives and methods (i.e., broader or variable focuses of interest, variable quality of reporting, and variable primary study designs and sample sizes). Because the SRs included in this report did not consistently report details about the populations nor provide consistent or clear definitions for measures of longevity, the variability across findings may also be attributable to these unknown variables. Nonetheless, the data on survival of complete and partial dentures at 5 years suggests that the majority of dentures are likely to demonstrate longevity across this time frame.

Similar to the 2015 CADTH report,¹³ the potential for risk of bias among the included studies in the review was identified.^16-23 In addition to the assessment of risk of bias conducted during the current review, several of the SRs included in this report acknowledged risk of bias identified among the primary research studies that they summarized.^16,17,20,21 This suggests that the evidence base informing the longevity of complete and partial dentures may still be characterized by limited methodological rigour (e.g., retrospective and other nonrandomized study designs, including small sample sizes)^16,18-21,23 and risk of bias (e.g., serious potential for confounding, selection, classification and reporting bias, as well as a lack of clarity in reporting).^17,22

Finally, the generalizability of the findings summarized in this report may be limited in their application to the Canadian context because the relevant primary studies described in the included SRs represented a broad range of populations by country of origin, with only 1 describing any relevant primary studies conducted in Canada.¹⁸ Nonetheless, the extent to whether studies from other countries bear relevance on the longevity of complete and partial dentures in the Canadian context remains unclear.

The wide range of findings, variability, and lack of clarity in reporting of the key study features described across the SRs included in this review indicate a continued need for clarity and consistency in the research informing the longevity of complete and partial dentures. Future research, ideally with prospective study designs and long-term follow-up, should aim for increased clarity and transparency in reporting of the populations, interventions (including types of materials from which dentures are constructed), and outcome definitions used in studies investigating the longevity of complete and partial dentures.

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20.de Luna Gomes JM, Lemos CAA, Santiago Junior JF, de Moraes SLD, Goiato MC, Pellizzer EP. Optimal number of implants for complete-arch implant-supported prostheses with a follow-up of at least 5 years: a systematic review and meta-analysis. J Prosthet Dent. 2019;121(5):766-774.e763. PubMed

21.Lemos CA, Verri FR, Batista VE, Junior JF, Mello CC, Pellizzer EP. Complete overdentures retained by mini implants: A systematic review. J Dent. 2017;57:4-13. PubMed

22.Moldovan O, Rudolph H, Luthardt RG. Clinical performance of removable dental prostheses in the moderately reduced dentition: a systematic literature review. Clin Oral Investig. 2016;20(7):1435-1447. PubMed

23.Sadowsky SJ, Zitzmann NU. Protocols for the maxillary implant overdenture: a systematic review. Int J Oral Maxillofac Implants. 2016;31 Suppl:s182-191. PubMed

24.Zou D, Wu Y, Huang W, Zhang Z, Zhang Z. A 5- to 8-year retrospective study comparing the clinical results of implant-supported telescopic crown versus bar overdentures in patients with edentulous maxillae. Int J Oral Maxillofac Implants. 2013;28(5):1322-1330. PubMed

Appendix 1: Selection of Included Studies

Figure 1: Selection of Included Studies

Appendix 2: Characteristics of Included Publications

Note that this table has not been copy-edited.

Table 2: Characteristics of Included Systematic Reviews

mo = month(s); NR = not reported; PEEK = polyetheretherketone; RCT = randomized controlled trial; SD = standard deviation; yr = year(s)

^aThe SR reports inclusion of 19 studies; there were 19 papers from primary studies included representing 18 studies.

^bIt is unclear from the study report of findings whether survival is reported for implants and prostheses together.

Appendix 3: Critical Appraisal of Included Publications

Note that this table has not been copy-edited.

Table 3: Strengths and Limitations of Systematic Reviews Using AMSTAR 2¹⁴

AMSTAR 2 = A Measurement Tool to Assess Systematic Reviews 2; NA = not applicable; PICO = population, intervention, comparator, outcome; RoB = risk of bias.

Appendix 4: Main Study Findings

Note that this table has not been copy-edited.

Table 4: Summary of Duration of Survival in Years — Complete Dentures

Table 5: Summary of Survival Rates Across Study Follow-Up — Complete Dentures

CI = confidence interval; mo = month(s); NR = not reported; SD = standard deviation; SR = systematic review; yr = year(s)

^aThese rates were reported as pooled weighted event rates of survival; due to the inconsistency observed across rates of survival reported for individual primary studies, these pooled data have been interpreted in this report as pooled weighted event rates of failure.

^bResults state survival as “100% (not specifically indicated)” (p. s189).

^cResults are reported for multiple subgroups without details as to group numbers or characteristics.

Table 6: Summary of Failure Rates Across Study Follow-Up — Complete Dentures

CI = confidence interval; mo = month(s); NR = not reported; SD = standard deviation; SR = systematic review; yr = year(s)

^aThese rates were reported as pooled weighted event rates of survival; due to the inconsistency observed across rates of survival reported for individual primary studies, these pooled data have been interpreted in this report as pooled weighted event rates of failure.

^bResults state survival as “100% (not specifically indicated)” (p. s189).

^cResults are reported for multiple subgroups without details as to group numbers or characteristics.

Table 7: Summary of Duration of Survival in Years — Metal Partial Dentures

Table 8: Summary of Survival Rates Across Study Follow-Up — Metal Partial Dentures

N/n = number(s); NR = not reported; SD = standard deviation; yr = year(s)

Table 9: Summary of Failure Rates Across Study Follow-Up — Metal Partial Dentures

N/n = number(s); NR = not reported; SD = standard deviation; yr = year(s)

Appendix 5: References of Potential Interest

Primary Studies

Hinz S, Bomicke W, Schweyen R, Bensel T. Ten-year clinical performance of non-precious metal double crowns with friction pins in severely reduced dentitions-a retrospective study. Clin Oral Investig. 2022 Nov 21;21:21. PubMed

Taylor M, Masood M, Mnatzaganian G. Complete denture replacement: a 20-year retrospective study of adults receiving publicly funded dental care. J Prosthodont Res. 2022 Jul 30;66(3):452-458. PubMed

Zierden K, Wostmann B, Rehmann P. Which patient-related factors influence the outcome of telescopic-retained removable implant-supported dental prostheses in edentulous patients? Int J Prosthodont. 2022 Sep-Oct;35(5):690-696. PubMed

Kurosaki Y, Kimura-Ono A, Mino T, et al. Six-year follow-up assessment of prosthesis survival and oral health-related quality of life in individuals with partial edentulism treated with three types of prosthodontic rehabilitation. J Prosthodont Res. 2021 Aug 21;65(3):332-339. PubMed

Yoshino K, Ito K, Kuroda M, Sugihara N. Survival rate of removable partial dentures with mandibular bilateral free end saddle: a retrospective study. Bull Tokyo Dent Coll. 2021 Dec 04;62(4):205-214. PubMed

Enkling N, Moazzin R, Geers G, Kokoschka S, Abou-Ayash S, Schimmel M. Clinical outcomes and bone-level alterations around one-piece mini dental implants retaining mandibular overdentures: 5-year follow-up of a prospective cohort study. Clin Oral Implants Res. 2020 Jun;31(6):549-556. PubMed

Brandt S, Winter A, Weigl P, Brandt J, Romanos G, Lauer HC. Conical zirconia telescoping into electroformed gold: a retrospective study of prostheses supported by teeth and/or implants. Clin Implant Dent Relat Res. 2019 Apr;21(2):317-323. PubMed

Fobbe H, Rammelsberg P, Lorenzo Bermejo J, Kappel S. The up-to-11-year survival and success of implants and abutment teeth under solely implant-supported and combined tooth-implant-supported double crown-retained removable dentures. Clin Oral Implants Res. 2019 Nov;30(11):1134-1141. PubMed

Hagiwara Y, Nakabayashi S, Ikeda T, Ito R. Ceria-stabilized zirconia/alumina nanocomposite for fabricating the framework of removable dental prostheses: preliminary results from a 4-year follow-up. Int J Prosthodont. 2019 May/Jun;32(3):254-256. PubMed

Klotz AL, Ott L, Krisam J, et al. Short-term performance of implant-supported restorations fitted in general dental practice: a retrospective study. Int J Oral Maxillofac Implants. 2019 September/October;34(5):1169-1176. PubMed

Marotti J, Gatzweiler B, Wolfart M, Sasse M, Kern M, Wolfart S. Implant placement under existing removable dental prostheses and the effect on follow-up and prosthetic maintenance. J Prosthodont. 2019 Feb;28(2):e752-e763. PubMed

Passia N, Wolfart S, Kern M. Ten-year clinical outcome of single implant-retained mandibular overdentures - a prospective pilot study. J Dent. 2019 03;82:63-65. PubMed

Schlenz MA, Schmidt A, Wostmann B, Rehmann P. Clinical performance of computer-engineered complete dentures: a retrospective pilot study. Quintessence Int. 2019;50(9):706-711. PubMed

Weigl P, Trimpou G, Lorenz J, Nentwig GH, Lauer HC. Prefabricated taper crowns for the retention of implant superstructures: three-year results of a prospective clinical trial. J Prosthet Dent. 2019 Apr;121(4):618-622. PubMed

Yamaga E, Sato Y, Soeda H, Minakuchi S. Relationship between oral health-related quality of life and usage period of complete dentures. Int J Prosthodont. 2019 Jul/Aug;32(4):327-332. PubMed

Zhang Y, Chow L, Siu A, Fokas G, Chow TW, Mattheos N. Patient-reported outcome measures (PROMs) and maintenance events in 2-implant-supported mandibular overdenture patients: a 5-year prospective study. Clin Oral Implants Res. 2019 Mar;30(3):261-276. PubMed

Nogueira TE, Aguiar FMO, de Barcelos BA, Leles CR. A 2-year prospective study of single-implant mandibular overdentures: patient-reported outcomes and prosthodontic events. Clin Oral Implants Res. 2018 Jun;29(6):541-550. PubMed

Ishida K, Nogawa T, Takayama Y, Saito M, Yokoyama A. Prognosis of double crown-retained removable dental prostheses compared with clasp-retained removable dental prostheses: a retrospective study. J Prosthodont Res. 2017 Jul;61(3):268-275. PubMed

Gherlone EF, Cappare P, Tecco S, et al. implant prosthetic rehabilitation in controlled hiv-positive patients: a prospective longitudinal study with 1-year follow-up. Clin Implant Dent Relat Res. 2016 Aug;18(4):725-734. PubMed

Mijiritsky E, Lorean A, Mazor Z, Levin L. Implant tooth-supported removable partial denture with at least 15-year long-term follow-up. Clin Implant Dent Relat Res. 2015 Oct;17(5):917-922. PubMed

Mundt T, Schwahn C, Stark T, Biffar R. Clinical response of edentulous people treated with mini dental implants in nine dental practices. Gerodontology. 2015 Sep;32(3):179-187. PubMed

Systematic Reviews With Interventions of Unclear Eligibility (Partial Denture Material Could Not Be Ascertained)

Badaro, M. M., et al. Narrow-diameter implants for partial fixed and removable prostheses: a systematic review and meta-analysis. Int J Prosthodontics. 2022;35(6): 738-751. PubMed

Molinero-Mourelle, P., et al. Clinical performance of tooth implant-supported removable partial dentures: a systematic review and meta-analysis. Clin Oral Invest. 2022;26(10): 6003-6014. PubMed

Bassetti, R. G., et al. Implant-assisted removable partial denture prostheses: a critical review of selected literature. Int J Prosthodontics. 2018;31(3): 287-302. PubMed

Lian, M., et al. Prognosis of combining remaining teeth and implants in double-crown-retained removable dental prostheses: a systematic review and meta-analysis. Int Journal Oral Maxillofacial Impl. 2018:33(2): 281-297. PubMed