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Clinical performance of anterior resin-bonded fixed dental prostheses with different framework designs: A systematic review and meta-analysis
Accepted Manuscript Title: Clinical performance of anterior resin-bonded fixed dental prostheses with different framework designs: A systematic review and meta-analysis Author: Ya-Ru Wei Xiao-Dong Wang Qin Zhang Xiang-Xia Li Markus B. Blatz Yu-Tao Jian Ke Zhao PII: DOI: Reference:
S0300-5712(16)30020-3 http://dx.doi.org/doi:10.1016/j.jdent.2016.02.003 JJOD 2583
To appear in:
Journal of Dentistry
Received date: Revised date: Accepted date:
5-4-2015 30-1-2016 9-2-2016
Please cite this article as: Wei Ya-Ru, Wang Xiao-Dong, Zhang Qin, Li Xiang-Xia, Blatz Markus B, Jian Yu-Tao, Zhao Ke.Clinical performance of anterior resin-bonded fixed dental prostheses with different framework designs: A systematic review and meta-analysis.Journal of Dentistry http://dx.doi.org/10.1016/j.jdent.2016.02.003 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Clinical performance of anterior resin-bonded fixed dental prostheses with different framework designs: A systematic review and meta-analysis Short title : Meta-analysis of resin-bonded fixed dental prostheses Ya-Ru Weia #, Xiao-Dong Wanga #, Qin Zhanga , Xiang-Xia Lia, Markus B. Blatzb, Yu-Tao Jianc *, Ke Zhaoa * a
Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong
Provincial Key Laboratory of Stomatology, Guangzhou, China b
Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental
Medicine, Philadelphia, Pennsylvania, United States c
Institute of Stomatological Research, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen
University, Guangzhou, China #
Joint first authors: these authors contributed equally to this work.
* Joint corresponding authors
Prof. Dr. Ke Zhao Department of Prosthodontics Hospital of Stomatology, Sun Yat-sen University 56 Lingyuan West Road, Guangzhou 510055, China Phone: +86 20 83802805 Fax: +86 20 83822807 E-mail: [email protected]
ABSTRACT Objectives: To systematically review the failure rate and complications of different framework designs of resin-bonded fixed dental prostheses (RBFDPs) in the anterior region. Methods: A systematic search for clinical studies on RBFDPs published prior to December 2014 in Medline/PubMed, EMBASE, and Cochrane Library databases was conducted and complemented by a manual search. Randomized controlled trials (RCTs) as well as prospective and retrospective cohort studies that compared at least two RBFDP framework designs with a minimum of 2 years follow up were included in this review. The quality of the included studies were assessed using the Newcastle-Ottawa scale for cohort studies and Cochrane Handbook for RCT. Prostheses-based data on reported failure rate / survival rate, debonding, and fractures were analyzed by meta-analysis. Results: Of 1010 screened articles, one RCT and 4 cohort studies fit the inclusion criteria and were included in the meta-analysis. All included articles have a high risk of bias. Failure rates of single-retainer cantilever RBFDPs were lower than two-retainer fixed-fixed RBFDPs (OR 0.42, 95% CI 0.19 to 0.94, P = 0.04). Metal-ceramic RBFDPs showed no difference of failure rates between cantilever RBFDPs and
1
two-retainer fixed-fixed RBFDPs (OR 0.93, 95% CI 0.33 to 2.63, P = 0.89). Debonding was not significantly different between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs (OR 0.61, 95% CI 0.23 to 1.60, P = 0.32). Metal-ceramic RBFDPs showed no difference of debonding between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs (OR 0.81, 95% CI 0.28 to 2.34, P = 0.70,) Conclusions: Within the limitations of the present study, cantilever RBFDPs demonstrate lower clinical failure than two-retainer RBFDPs in the anterior region. The failure of metal-ceramic RBFDPs is independent of the framework design, while the failure of all-ceramic RBFDPs with different designs has not been clear yet. Clinical significance: Based on the principle of minimally invasive treatment, less number of retainers is recommended for RBFDPs.
Key words：Denture, Resin-bonded, Systematic review, Meta-analysis
Introduction Since the introduction of resin-bonded fixed dental prostheses (RBFDPs) in the 1970s, this conservative treatment option has become well accepted to replace missing anterior teeth.1 RBFDPs may provide a promising alternative to dental implants in cases of insufficient bone or other anatomical, medical, or economical limitations.2 They should also be considered in juveniles when implants are not considered an appropriate option as RBFDPs provide a minimally invasive treatment that can be readily replaced or altered.3 According to the dental literature, survival rates of RBFDPs vary widely from 59% to 100%.4,5 RBFDPs have shown acceptable survival rates of 87.7% in medium-term observations in a systematic review.6 Causes for RBFDP failure include debonding,7 secondary caries on the abutment teeth,2 and fracture of the retainers,8 for which debonding is the most common.7 Therefore, survival of RBFDPs is determined by tooth preparation design, mechanical properties of the prosthetic materials and quality of the adhesive bond.9 Anterior RBFDP frameworks are designed with either one (cantilever), two (fixed-fixed), or multiple retainers.4,5,10,11 The influence of these design options on the clinical performance and survival of anterior PRBFDP’s is controversial. The two-retainer fixed-fixed design has been the most popular and reportedly provides a higher fracture resistance than with a cantilever.12 In contrast, results of a clinical study demonstrate that two-retainer fixed-fixed RBFDPs have a higher fracture rate than cantilever RBFDPs.13 A cantilever design has shown significantly better performance than a two-retainer fixed-fixed one in a 10-year clinical study, with survival rates of 94.4% and 67.3%, resepctively.14 The cantilever design appears to be more resistant to debonding caused by occlusal loading15 and has been recommended as the preferred treatment approach.16 The application of minimally invasive and resin-bonded treatment concepts has dramatically increased in recent years. However, the impact of the framework design on clinical performance of RBFDPs has not been sufficiently assessed with an evidence-based approach. Therefore, the purpose of this article was to 2
systematically review the existing literature and assess the evidence as to the influence of different RBFDP framework designs on clinical survival of these restorations.
Materials and Methods A systematic review and meta-analysis were conducted after searching electronic databases (Medline/PubMed, EMBASE, and Cochrane Library) for articles published in English between 1967 and December 2014 based on clinical studies with human subjects only. The MeSH terms and text words included: “fixed dental prostheses”, “resin-bonded bridges”, “resin-bonded fixed dental prostheses”, “adhesive bridges”, “acid-etched bridges”, “single-retainer”, and “two-retainer”. A similar search was conducted of the Chinese Biomedical Literature Database (CBM) of the Chinese literature. WHO ICTRP Search Portal (WHO International Clinical Trials Registry Platform Search Portal) for also retrieving ongoing studies. To increase the yield of the relevent studies, references of all full-text articles and related reviews were searched manually. All the titles and abstracts were screened based on the inclusion and exclusion criteria (Table 1) by two independent reviewers. Subsequently, the full texts were collected after agreement on titles and abstracts, and assessed independently by the same reviewers. Any disagreement was resolved by collegial discussion, or by an independent third reviewer when necessary. Studies meeting inclusion criteria underwent validity assessment. The full texts that did not meet the inclusion criteria were excluded. The process for selecting studies is outlined in Fig. 1. The data provided by the selected studies should contain quantitative outcomes, such as; survival rates / failure rates, debonding, fracture, and other biological complication rates. Two reviewers extracted the complication data rates independently using a purpose designed data collection form. When specific data was unclear or missing, the corresponding author of the relevant publication was contacted via e-mails for further clarification. Survival in this study was defined as the RBFDP prostheses remaining in situ without modification during the observation period. The bias and quality of the included studies were assessed using the Newcastle-Ottawa scale for cohort studies, including patient selection, comparability of groups and ascertainment of outcome.17 Studies were evaluated on the basis of a star scoring scale with higher scores for higher quality studies.17 For randomized controlled trials (RCTs), bias assessment was conducted following the Cochrane Handbook for Systematic Reviews of Interventions.18 Data pooling was subjected to meta-analysis to estimate the odds ratio (OR) and 95% confidence intervals (CI) with a fixed effect model by the Cochrane Collaboration Review Manager (Rev Man, Version 5). Risk estimates of OR and 95% CI were calculated for dichotomous data. The heterogeneity between studies was analyzed using Cochran’s Q test and I2. Pre-specified subgroup analysis was evaluated according to the materials used (all-ceramic & metal-ceramic).Statistical analyses were performed with statistical software (Comprehensive Meta Analysis® version 2.0). Differences were considered statistically significant at the level of 0.05. Results One thousand and ten articles were screened from the electronic search for possible inclusion in the study. A consensus on the studies to be selected was reached after discussion; 969 articles were excluded on
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the basis of the title and abstract. The reasons for excluding the articles were as follows; either there was a lack of specific data on cantilever or fixed-fixed RBFDPs, they were; case reports, in vitro or non-clinical studies. Full-text articles were obtained for the 41 selected publications. Hand searches were performed on bibliographies of the selected articles as well as of identified narrative reviews. The hand search did not identify any additional articles that matched the inclusion criteria. Thirty-six articles were excluded from the final analysis, resulting in the inclusion of 5 studies. The reasons for exclusion are listed in Table 2. Only one RCT was included13. With the lack of RCTs, clinical controlled trials, prospective and retrospective cohort studies comparing at least two designs of RBFDP were also included into this study and selected for meta-analysis. Two of the 5 included studies were prospective cohort studies14,19 and two were retrospective cohort studies (Table 3).20,21 Details of methodological characteristics are summarized in Table 4. The assessment of risk of bias is presented in Table 5 and Table 6. The RCT had a high risk of bias since the details of random sequence generation, blinding, and other sources of bias were not clarified in the study. The Newcastle-Ottawa scores of cohort studies ranged from 3 to 4 stars with a high risk of bias. There is no star ranking possible for the comparability, since none of the cohort studies described the baseline control for patient selection. Failure rate Four of the 5 included studies demonstrated a lower failure rate for cantilever RBFDPs.13,14,19,21 The results of estimated failure rate for cantilever RBFDPs and two-retainer fixed-fixed RBFDPs are shown in Fig. 2. Cantilever RBFDPs demonstrated lower failure rates (OR 0.42, 95% CI 0.19 to 0.94, Z = 2.10, P = 0.04). Heterogeneity among studies was not indicated (Q = 6.49, P = 0.17, I2 = 38%). Failure rate of metal-ceramic RBFDPs Metal-ceramic RBFDPs showed no difference of failure rates between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs (OR 0.93, 95% CI 0.33 to 2.63, Z = 0.14, P = 0.89, Fig. 3). Heterogeneity among studies was not observed (Q = 0.77, P = 0.68, I2 = 0%, Fig. 3). Failure rate of all ceramic RBFDPs All ceramic RBFDPs showed 10-year failure rate of 26.1% in the two-retainer fixed-fixed group and 5.6% in the cantilever group, which was not statistically significant.14 Two two-retainer fixed-fixed RBFDPs lost bond, and one retainer of a two-retainer fixed-fixed RBFDP fractured in another included study (N = 10), whereas no cantilever RBFDP failed.19 No meta-analysis was conducted in this study, as only two studies were included. Debonding rate Three studies reported no debonding of cantilever RBFDPs,13,14,19 whereas one reported no debonding in two-retainer fixed-fixed RBFDPs.14 No difference between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs as shown in Fig. 4 (OR 0.61, 95% CI 0.23 to 1.60, Z = 1.00, P = 0.32). Heterogeneity among studies was not observed (Q = 2.59, P = 0.46, I2 = 0%).
4
Debonding rate of metal-ceramic RBFDPs Three studies using metal-ceramic RBFDPs showed no difference of debonding between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs in Fig. 5 (OR 0.81, 95% CI 0.28 to 2.34, Z = 0.39, P = 0.70,).13,20,21 Heterogeneity among studies was not indicated (Q = 1.09, P = 0.58, I2 = 0%, Fig. 5). Debonding rate of all ceramic RBFDPs No debonding was found in two RBFDPs designs in the study of 10-year all-ceramic RBFDPs.14 In Zhou’s study, two two-retainer fixed-fixed RBFDPs and none of cantilever RBFDPs lost bond, but no statistical analysis was conducted. 19 No meta-analysis was conducted, as only two studies were included. Due to the limited studies included, meta-regression could not be performed to evaluate the influence between different factors such as prostheses materials, luting cements, and retention of tooth preparation.
Discussion The results of this meta analysis suggest that cantilever RBFDPs have better survival rates compared to two-retainer fixed-fixed RBFDPs, which is in contrast to one previous study that found two-retainer fixed-fixed RBFDPs had a better prognosis at 48 and 60 months survival rate of 71% as compared to cantilever RBFDPs with 61% survival.21 Other studies, however, reveal better survival rates with cantilever than with fixed-fixed RBFDPs.22,23 According to other clinical trials, two-unit cantilever RBFDPs perform as well as or even better than 3-unit two-retainer fixed-fixed RBFDPs.24,25 The main reason for the higher failure rate of two-retainer fixed-fixed RBFDPs appears to be the mobility and differential movement of the abutment teeth during function, especially during protrusive and lateral movements under tooth contact, and the rigid connection with the two mobile elements. For the cantilever RBFDP, however, the pontic always moves with the abutment tooth, which limits shear and torque forces on the pontics and connectors.14 This result has been supported by in vitro research in which cantilever RBFDPs demonstrated a significantly higher bond strength than fixed-fixed framework designs after a fatigue test of 12000 load cycles.26 For other multi-retainer RBFDPs, a 75% survival rate was reported for frameworks with 2 to 5 retainers.27 There is no evidence that multiple retainers improve longevity of resin-bonded prostheses. In light of the fact that RBFDPs are applied as a minimally invasive treatment option, one may argue that, based on this evidence, the preferred framework design should be the cantilever design as it requires preparation of only one abutment tooth. No meta-analysis was conducted for all-ceramic in this study. In Kern and Zhou’s study, all-ceramic RBFDPs are more likely to fracture at the connector areas, which increase the failure probability of the prostheses. Hot-pressed casting ceramic (IPS Empress and IPS e.max Press) demonstrated a survival rate of 100% after 1 year and a 88.5% after 3 years follow-up for RBFDPs in the anterior region.19,22 The limited flexural strength and toughness of these silicate ceramics requires that recommended connector dimensions, which have to be larger as compared to ceramics with greater strength. Cantilever RBFDPs made from glass-infiltrated ceramic In-Ceram zirconia (containing about 26% zirconia) resulted in 94.4% survival rate in a long-term study with 10 years follow up.14 However, connector fracture is not the common failure for metal-ceramic RBFDPs.28 No significant difference between cantilever and fixed-fixed design for
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metal-ceramic RBFDPs was detected. Fiber-reinforced composite RBFDPs have favorable esthetic outcomes but may not provide sufficient strength. This material can only be used with a two-retained fixed-fixed RBFDP design.29 A medium observation time of 5 years of fiber-reinforced composite RBFDPs shows 75-77% survival rates.27,30 As concluded in a literature review of different materials for RBFDPs, the most frequent complications were debonding for metal-ceramic RBFDPs, fracture for all-ceramic RBFDPs, and delamination of the composite veneering material for the fiber-reinforced composite rstorations.31 Proper, enamel-preserving tooth preparation may influence retention of RBFDPs. Preparation designs with or without retention form varied among the studies reported. Within this meta-analysis, only one study reported tooth preparation with retention form.13 Two studies reported tooth preparation without retention form and only lingual rests to allow a defined insertion of the restoration during bonding.14,19 Two studies did not identify the type of tooth preparation due to them being retrospective study designs.20,21 Tooth preparation with retention forms, such as proximal boxes, grooves, and pin holes, were suggested to enhance the survival rate for RBFDPs.32 In contrast, survival rate of cantilever RBFDPs without retention form of tooth preparation showed a favorable result of 93.1% after 5-year follow-up. Tooth preparation might not need retention forms with the use of resin cements, but a lingual rest to ensure the accurate seating of the RBFDP is universally recomended.8 However, due to the small sample size of existing clinical data, conclusions should be drawn carefully. The survival of RBFDP restorations seems to rely on the resin bond and not on any additional mechanical retention. Clinical outcomes with RBFDPs using either Panavia 21 TC (Kuraray, Kurashiki, Japan) or Multilink-Automix bonding system (Ivoclar Vivadent, Schaan, Liechtenstein) did not differ within the first 5 years.8 In case of metal-ceramic RBFDP, congruous results were observed when comparing Panavia F (Kuraray, Osaka, Japan) and Super-Bond C&B (Sun medical, Moriyama, Japan).9 Thus, different resin cements might not have an influence on the risk of failure for RBFDP in clinical practice.33 To ensure a dry working area, the use of a rubber dam is recommended. Two studies applied rubber-dam, whereas one study applied cotton rolls, and one study applied both rubber-dam and cotton roll for controlling saliva contamination.13,14,19,20,21 Cases applied with rubber-dam reported less incidence of debonding than the ones with cotton rolls only.20 Therefore, rubber-dam application appears to be positively correlated to the survival of RBFDPs.34 Air-particle abrasion provided better retention for metal-framework RBFDPs.13,21 Similarly, long-term bond strength studies to glass-infiltrated ceramics was greatly affected by surface treatment.35 The preferred surface treatment methods include, tribochemical silica coating and silanization (Rocatec, 3M ESPE, Seefeld, Germany) of the alumina ceramic, followed by application of a phosphate-monomer-containing composite resin.36 Air-particle abrasion with 50 μm alumina particles at 1.0-2.5 bar and use of a phosphate-monomer-containing composite resin luting agent are preferred bonding methods.37,38 As 10-methacryloyloxydecyldihydrogenphosphate (MDP) forms a water-resistant chemical bond with zirconia, MDP-containing resin cement is a popular choice for luting zirconia prostheses in clinical
6
applications.23 Moreover, application of a MDP-containing priming agent to the air-particle abraded surface has been shown to significantly enhance bond strengths of composite-resin luting agents to zirconia.39,40 In a prospective study, cantilever single-retainer CAD/CAM fabricated zirconia RBFDPs present an alternative treatment option, offering good esthetics, a minimally invasive preparation, high biocompatibility, and of most importance, a 100% survival rate of with no fracture occurrence after 5 years.41 However, there is lack of clinical trials comparing CAD/CAM fabricated two-retainer fixed-fixed RBFDPs and cantilever single-retainer RBFDPs, and more further investigations are needed. The evidence presented and currently available relates to the data mainly from prospective and retrospective cohort studies, as there is a lack of RCTs available, which may be due to widespread concerns about cantilever FDP designs.42 The methodological assessment of included studies was not satisfactory. Among the included studies, the RCT did not specifically clarify randomisation methods and blindness, resulting in a potential selection and detection bias, consequently the quality of evidence from this study was very low. None of the cohort studies provided comparability, which resulted in low Newcastle-Ottawa scales and low evidence level grading. Additionally, abstracts of grey articles and articles published in other languages were not followed up, which might result in selection bias. Therefore, when interpreting the results it should be born in mind that the evidence level has been weakened by the poor quality control, and well designed RCTs with large sample size are still needed.
Conclusions Based on the results of mainly cohort studies, because of the lack of high quality RCTs, cantilever RBFDPs demonstrate lower clinical failure than two-retainer RBFDPs in the anterior region. The failure of metal-ceramic RBFDPs is independent of the framework design, while the failure of all-ceramic RBFDPs with different designs has not been clear yet.
Acknowledgements The authors would like to express their gratitude for assistance from the Chinese Evidence-Based Medicine Center. They would also like to thank Prof. Matthias Kern (Department of Prosthodontics, Christian-Albrechts University, Kiel, Germany) and Dr. Tuan-feng Zhou (Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China) for the additional data from their clinical trials.
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References 1. Kern M, Knode H, Strub JR. The all-porcelain, resin-bonded bridge. Quintessence International 1991;22:257-62. 2. Kern M, Gläser R. Cantilevered all-ceramic, resin-bonded fixed partial dentures: a new treatment modality. Journal of Esthetic Dentistry 1997;9:255-64. 3. Weng D, Ries S, Richter EJ. Treatment of a juvenile patient with a maxillary all-ceramic resin-bonded fixed partial denture: a case report. Quintessence International 2002;33:584-8. 4. Kuhlke KL, Drennon DG. An alternative single-tooth removable partial denture. Journal of the International Association of Dentistry for Children 1977;8:11-5. 5. Creugers NH, van’t Hof MA, Vrijhoef M. A clinical comparison of three types of resin-retained cast metal prostheses. Journal of Prosthetic Dentistry 1986;56:297-300. 6. Pjetursson BE, Tan WC, Tan K, Brägger U, Zwahlen M, Lang NP. A systematic review of the survival and complication rates of resin-bonded bridges after an observation period of at least 5 years. Clinical Oral Implants Research 2008;19:131-41. 7. Gratton DR, Jordan RE, Teteruck WR. Resin-bonded bridges: the state of the art. Ontario Dentist 1983;60:9-11,13-6,18-9. 8. Sasse M, Eschbach S, Kern M. Randomized clinical trial on single retainer all-ceramic resin-bonded fixed partial dentures: influence of the bonding system after up to 55 months. Journal of Dentistry 2012;40:783-6. 9. Dündar M, Ozcan M, Cömlekoğlu ME, Güngör MA. A preliminary report on short-term clinical outcomes of three-unit resin-bonded fixed prostheses using two adhesive cements and surface conditioning combinations. International Journal of Prosthodontics 2010;23:353-60. 10. Livaditis GJ, Thompson VP. Etched castings: an improved retentive mechanism for resin-bonded retainers. Journal of Prosthetic Dentistry 1982;47:52-8. 11. van Dalen A, Feilzer AJ, Kleverlaan CJ. A literature review of two-unit cantilevered FPDs. International Journal of Prosthodontics 2004;17:281-4. 12. Rosentritt M, Ries S, Kolbeck C, Westphal M, Richter EJ, Handel G. Fracture characteristics of anterior resin-bonded zirconia-fixed partial dentures. Clinical Oral Investigations 2009;13:453-7. 13. Chan AW, Barnes IE. A prospective study of cantilever resin-bonded bridges: an initial report. Australian Dental Journal 2000;45:31-6. 14. Kern M, Sasse M. Ten-year survival of anterior all-ceramic resin-bonded fixed dental prostheses. Journal of Adhesive Dentistry 2011;13:407-10. 15. Johnston CD, Hussey DL. The immediate replacement of incisor teeth by cantilevered resin-bonded bridgework. Dental Update 1993;20:333-4. 16. Kern M. Clinical long-term survival of two-retainer and single-retainer all-ceramic resin-bonded fixed partial dentures. Quintessence International 2005;36:141-7. 17. Stang A. Critical evaluation of the Newcastle-Ottawa scale for the
assessment of the quality of
nonrandomized studies in meta-analyses. Eur J Epidemiol 2010;25:603-5.
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18. Higgins JPT, Green S. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated
March
2011].
The
Cochrane
Collaboration,
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Available
from
www.cochrane-handbook.org. 19. Zhou TF, Wang XZ, Zhang GR. All-ceramic resin bonded fixed partial denture made of IPS hot-pressed casting porcelain restore anterior missing teeth: a three years clinical observation. Journal of Peking University (Health Sciences) 2011;43:77-80. 20. Garnett MJ, Wassell RW, Jepson NJ, Nohl FS. Survival of resin-bonded bridgework provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors. British Dental Journal 2006;201: 525,527-34. 21. Chai J, Chu FC, Newsome PR, Chow TW. Retrospective survival analysis of 3-unit fixed-fixed and 2-unit cantilevered fixed partial dentures. Journal of Oral Rehabilitation 2005;32:759-65. 22. Zhang L, Nie YG, Xie QF. Clinical application of anterior all-ceramic cantilevered resin-bonded fixed partial dentures. Chinese Journal of Stomatology 2008;43:209-11. 23. Creugers NH, Snoek PA, Van 't Hof MA, Käyser AF. Clinical performance of resin-bonded bridges: a 5-year prospective study. Part III: Failure characteristics and survival after rebonding. Journal of Oral Rehabilitation 1990;17:179-86. 24. Chan AW, Barnes IE. A prospective study of cantilever resin-bonded bridges: an initial report. Australian Dental Journal 2000;45:31-6. 25. Djemal S, Setchell D, King P, Wickens J. Long-term survival characteristics of 832 resin-retained bridges and splints provided in a post-graduate teaching hospital between 1978 and 1993. Journal of Oral Rehabilitation 1999;26:302-20. 26. Wong TL, Botelho MG. The fatigue bond strength of fixed-fixed versus cantilever resin-bonded partial fixed dental prostheses. Journal of Prosthetic Dentistry 2014;111:136-41. 27. Vallittu PK. Survival rates of resin-bonded, glass fiber-reinforced composite fixed partial dentures with a mean follow-up of 42 months: a pilot study. Journal of Prosthetic Dentistry 2004;91:241-6. 28. Hussey DL, Pagni C, Linden GJ. Performance of 400 adhesive bridges fitted in a restorative dentistry department. Journal of Dentistry 1991;19:221-5. 29. Burke FJ. Resin-retained bridges: fiber-reinforced versus metal. Dental Update 2008;35:521-2, 524-6. 30. van Heumen CC, Tanner J, van Dijken JW, Pikaar R, Lassila LV, Creugers NH, et al. Five-year survival of 3-unit fiber-reinforced composite fixed partial dentures in the posterior area. Dental Materials 2010;26:954-60. 31. Miettinen M, Millar BJ. A review of the success and failure characteristics of resin-bonded bridges. British Dental Journal 2013;215:E3. 32. Behr M, Leibrock A, Stich W, Rammelsberg P, Rosentritt M, Handel G. Adhesive-fixed partial dentures in anterior and posterior areas: results of an on-going prospective study begun in 1985. Clinical Oral Investigations 1998;2:31-5. 33. Hussey DL, Linden GJ. The clinical performance of cantilevered resin-bonded bridgework. Journal of Dentistry 1996;24:251-6.
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34. Creugers NHJ, De Kanter RJAM, Verzijden CWGJM, Van’t Hof MA. Risk factors and multiple failures in posterior resin-bonded bridges in a 5-year multi-practice clinical trial. Journal of Dentistry 1998;26:397-402. 35. Kern M, Thompson VP. Bonding to a glass infiltrated alumina ceramic: Adhesion methods and their durability. Journal of Prosthetic Dentistry 1995;73:240-9. 36. van Dalen A, Feilzer AJ, Kleverlaan CJ. The influence of surface treatment and luting cement on in vitro behavior of two-unit cantilever resin-bonded bridges. Dental Materials 2005;21:625-32. 37. Blatz MB, Sadan A, Kern M. Resin-ceramic bonding: a review of the literature. Journal of Prosthetic Dentistry 2003;89:268-74. 38. Wegner SM, Kern M. Long-term resin bond strength to zirconia ceramic. Journal of Adhesive Dentistry 2000;2:139-47. 39. Blatz MB, Chiche G, Holst S, Sadan A. Influence of surface treatment and simulated aging on bond strengths of luting agents to zirconia. Quintessence International 2007;38:745-53. 40. Tanaka R, Fujishima A, Shibata Y, Manabe A, Miyazaki T. Cooperation of phosphate monomer and silica modification on zirconia. Journal of Dental Research 2008;87:666-70. 41. Sasse M, Kern M. CAD/CAM single retainer zirconia-ceramic resin-bonded fixed dental prostheses: clinical outcome after 5 years. International Journal of Computerized Dentistry 2013;16:109-18. 42. Walls AW. Cantilever FPDs have lower success rates than end abutted FPDs after 10-year of follow-up. Journal of Evidence Based Dental Practice 2010;10:41-3.
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Fig. 1 - Results of the article search
11
Fig. 2 - Results of meta-analysis for failure rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
12
Fig. 3 - Metal-ceramic results of meta-analysis for failure rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
13
Fig. 4 - Results of meta-analysis for debonding rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
14
Fig. 5 - Metal-ceramic results of meta-analysis for debonding rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
15
Table 1 - Inclusion and exclusion criteria Inclusion Criteria Type of study
Type of patients (P) Type of interventions (I) Type of control (C) Type of outcomes (O) Exclusion Criteria Type of study Type of interventions Follow-up time Outcomes
Randomized-controlled clinical trials (RCTs) Prospective or retrospective cohort studies; Clinical controlled trials (CCT) (when lack of RCTs) Anterior teeth missing patients treated by RBFDPs Anterior teeth missing patients treated by cantilever RBFDPs Anterior teeth missing patients treated by two-retainer fixed-fixed RBFDPs in the same study Reporting the details of mechanical or biological complications incidence Case reports, case series, animal studies and in-vitro studies Not including cantilever or fixed-fixed resin-bonded fixed dental prosthesis Less than 2 years No detailed clinical outcomes but only questionnaire and survey follow-up Multiple publications on the same patient cohorts.
16
Table 2 - Number of studies excluded with regard to each exclusion criteria Exclusion Criteria
Number of studies
Not reporting designs of resin-bonded fixed partial dentures
24
Multiple publications on the same patient cohort
3
Follow-up time less than 2 years
2
No clinical visit follow-up, only questionnaire and survey follow-up
7
17
Table 3 - Study and patient characteristics of the included studies Mean follow-up
Study
Year
Study design
Kern et al.14
2011
Prospective cohort study
111
38
Not reported
0
Zhou et al.19
2011
Prospective cohort study
41.3
26
>18
0
Garnett et al.20
2006
Retrospective cohort study
59.3
71
11 ~ 43
Not reported
Chai et al.21
2005
Retrospective cohort study
47
33
Not reported
Not reported
Chan et al.13
2000
34
25
15~56
Randomized controlled trial
time (month)
18
No. of prostheses
Age range
Drop out
0
Table 4 - Methodological characteristics of included studies Manufacturing Procedure Study
Prosthesis design
Location
Material In Ceram
Kern et al.14†
cantilever =22 fixed-fixed =16
Anterior
Alumina In Ceram
Clinical Considerations
Surface treatment
Tooth preparation
Isolation method
Failures Bonding system
Debond
Fracture
cantilever =0
1
fixed-fixed =0
6
cantilever =0
0
fixed-fixed =2
1
cantilever =25
0
fixed-fixed =3
0
cantilever =2
0
fixed-fixed =3
0
cantilever =0
0
fixed-fixed =1
0
A lingual veneer, a groove
Tribochemically silica coated and silanated
on the cingulum, a small proximal box (2mm x
Rubber-dam
Panavia TC
Cotton roll
Variolink II
1mm x 0.5mm)
Zirconia Zhou et al.19†
Garnett et al.20
21
Chai et al.
Chan et al.
†
cantilever =16 fixed-fixed =10 cantilever =62 fixed-fixed =9
cantilever =18 fixed-fixed =15
13
cantilever =13 fixed-fixed =12
Anterior
Anterior
IPS Empress E.max Metal-ceramic
2% HF 60s
No retention form
Not reported
Not reported
Air-abraded Anterior
Metal-ceramic
50μm
Rubber-dam used in 6 bridges only
Panavia
with
alumina
Not reported
Not reported
Panavia
Rubber-dam
Panavia
particles
Gritblasted Anterior
Metal-ceramic
50μm
with alumina
particles
Some with retention form (proximal
grooves
additional rests)
Detailed information was collected by personal communication with the corresponding author via email.
19
and
Table 5 - Quality assessment of the included studies with the Newcastle-Ottawa Scale
Coding Manual for Cohort Studies Kern et al.
14
Zhou et al.19
Garnett et al.20
SELECTION 1) Representativeness of the exposed cohort 2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale SELECTION 1) Representativeness of the exposed cohort 2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale SELECTION 1) Representativeness of the exposed cohort
20
Newcastle-Ottawa Scale d c a★ a★
a★ a★ a★ ★★★★★ d c a★ a★
a★ b a★ ★★★★ d
Chai et al.21
2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale SELECTION 1) Representativeness of the exposed cohort 2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale
21
c a★ b
a★ a★ d ★★★ d c a★ b
a★ b d ★★
Table 6 - Quality assessment of the included study with Cochrane Handbook for Systematic Reviews of Interventions Study
Chan et al.13
Random sequence
Allocation
generation
concealment
Unclear
Unclear
Blinding
Data
Selective report
integrity Unclear
22
Adequate
Other sources of bias
Adequate
Yes
S0300-5712(16)30020-3 http://dx.doi.org/doi:10.1016/j.jdent.2016.02.003 JJOD 2583
To appear in:
Journal of Dentistry
Received date: Revised date: Accepted date:
5-4-2015 30-1-2016 9-2-2016
Please cite this article as: Wei Ya-Ru, Wang Xiao-Dong, Zhang Qin, Li Xiang-Xia, Blatz Markus B, Jian Yu-Tao, Zhao Ke.Clinical performance of anterior resin-bonded fixed dental prostheses with different framework designs: A systematic review and meta-analysis.Journal of Dentistry http://dx.doi.org/10.1016/j.jdent.2016.02.003 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Clinical performance of anterior resin-bonded fixed dental prostheses with different framework designs: A systematic review and meta-analysis Short title : Meta-analysis of resin-bonded fixed dental prostheses Ya-Ru Weia #, Xiao-Dong Wanga #, Qin Zhanga , Xiang-Xia Lia, Markus B. Blatzb, Yu-Tao Jianc *, Ke Zhaoa * a
Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong
Provincial Key Laboratory of Stomatology, Guangzhou, China b
Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental
Medicine, Philadelphia, Pennsylvania, United States c
Institute of Stomatological Research, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen
University, Guangzhou, China #
Joint first authors: these authors contributed equally to this work.
* Joint corresponding authors
Prof. Dr. Ke Zhao Department of Prosthodontics Hospital of Stomatology, Sun Yat-sen University 56 Lingyuan West Road, Guangzhou 510055, China Phone: +86 20 83802805 Fax: +86 20 83822807 E-mail: [email protected]
ABSTRACT Objectives: To systematically review the failure rate and complications of different framework designs of resin-bonded fixed dental prostheses (RBFDPs) in the anterior region. Methods: A systematic search for clinical studies on RBFDPs published prior to December 2014 in Medline/PubMed, EMBASE, and Cochrane Library databases was conducted and complemented by a manual search. Randomized controlled trials (RCTs) as well as prospective and retrospective cohort studies that compared at least two RBFDP framework designs with a minimum of 2 years follow up were included in this review. The quality of the included studies were assessed using the Newcastle-Ottawa scale for cohort studies and Cochrane Handbook for RCT. Prostheses-based data on reported failure rate / survival rate, debonding, and fractures were analyzed by meta-analysis. Results: Of 1010 screened articles, one RCT and 4 cohort studies fit the inclusion criteria and were included in the meta-analysis. All included articles have a high risk of bias. Failure rates of single-retainer cantilever RBFDPs were lower than two-retainer fixed-fixed RBFDPs (OR 0.42, 95% CI 0.19 to 0.94, P = 0.04). Metal-ceramic RBFDPs showed no difference of failure rates between cantilever RBFDPs and
1
two-retainer fixed-fixed RBFDPs (OR 0.93, 95% CI 0.33 to 2.63, P = 0.89). Debonding was not significantly different between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs (OR 0.61, 95% CI 0.23 to 1.60, P = 0.32). Metal-ceramic RBFDPs showed no difference of debonding between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs (OR 0.81, 95% CI 0.28 to 2.34, P = 0.70,) Conclusions: Within the limitations of the present study, cantilever RBFDPs demonstrate lower clinical failure than two-retainer RBFDPs in the anterior region. The failure of metal-ceramic RBFDPs is independent of the framework design, while the failure of all-ceramic RBFDPs with different designs has not been clear yet. Clinical significance: Based on the principle of minimally invasive treatment, less number of retainers is recommended for RBFDPs.
Key words：Denture, Resin-bonded, Systematic review, Meta-analysis
Introduction Since the introduction of resin-bonded fixed dental prostheses (RBFDPs) in the 1970s, this conservative treatment option has become well accepted to replace missing anterior teeth.1 RBFDPs may provide a promising alternative to dental implants in cases of insufficient bone or other anatomical, medical, or economical limitations.2 They should also be considered in juveniles when implants are not considered an appropriate option as RBFDPs provide a minimally invasive treatment that can be readily replaced or altered.3 According to the dental literature, survival rates of RBFDPs vary widely from 59% to 100%.4,5 RBFDPs have shown acceptable survival rates of 87.7% in medium-term observations in a systematic review.6 Causes for RBFDP failure include debonding,7 secondary caries on the abutment teeth,2 and fracture of the retainers,8 for which debonding is the most common.7 Therefore, survival of RBFDPs is determined by tooth preparation design, mechanical properties of the prosthetic materials and quality of the adhesive bond.9 Anterior RBFDP frameworks are designed with either one (cantilever), two (fixed-fixed), or multiple retainers.4,5,10,11 The influence of these design options on the clinical performance and survival of anterior PRBFDP’s is controversial. The two-retainer fixed-fixed design has been the most popular and reportedly provides a higher fracture resistance than with a cantilever.12 In contrast, results of a clinical study demonstrate that two-retainer fixed-fixed RBFDPs have a higher fracture rate than cantilever RBFDPs.13 A cantilever design has shown significantly better performance than a two-retainer fixed-fixed one in a 10-year clinical study, with survival rates of 94.4% and 67.3%, resepctively.14 The cantilever design appears to be more resistant to debonding caused by occlusal loading15 and has been recommended as the preferred treatment approach.16 The application of minimally invasive and resin-bonded treatment concepts has dramatically increased in recent years. However, the impact of the framework design on clinical performance of RBFDPs has not been sufficiently assessed with an evidence-based approach. Therefore, the purpose of this article was to 2
systematically review the existing literature and assess the evidence as to the influence of different RBFDP framework designs on clinical survival of these restorations.
Materials and Methods A systematic review and meta-analysis were conducted after searching electronic databases (Medline/PubMed, EMBASE, and Cochrane Library) for articles published in English between 1967 and December 2014 based on clinical studies with human subjects only. The MeSH terms and text words included: “fixed dental prostheses”, “resin-bonded bridges”, “resin-bonded fixed dental prostheses”, “adhesive bridges”, “acid-etched bridges”, “single-retainer”, and “two-retainer”. A similar search was conducted of the Chinese Biomedical Literature Database (CBM) of the Chinese literature. WHO ICTRP Search Portal (WHO International Clinical Trials Registry Platform Search Portal) for also retrieving ongoing studies. To increase the yield of the relevent studies, references of all full-text articles and related reviews were searched manually. All the titles and abstracts were screened based on the inclusion and exclusion criteria (Table 1) by two independent reviewers. Subsequently, the full texts were collected after agreement on titles and abstracts, and assessed independently by the same reviewers. Any disagreement was resolved by collegial discussion, or by an independent third reviewer when necessary. Studies meeting inclusion criteria underwent validity assessment. The full texts that did not meet the inclusion criteria were excluded. The process for selecting studies is outlined in Fig. 1. The data provided by the selected studies should contain quantitative outcomes, such as; survival rates / failure rates, debonding, fracture, and other biological complication rates. Two reviewers extracted the complication data rates independently using a purpose designed data collection form. When specific data was unclear or missing, the corresponding author of the relevant publication was contacted via e-mails for further clarification. Survival in this study was defined as the RBFDP prostheses remaining in situ without modification during the observation period. The bias and quality of the included studies were assessed using the Newcastle-Ottawa scale for cohort studies, including patient selection, comparability of groups and ascertainment of outcome.17 Studies were evaluated on the basis of a star scoring scale with higher scores for higher quality studies.17 For randomized controlled trials (RCTs), bias assessment was conducted following the Cochrane Handbook for Systematic Reviews of Interventions.18 Data pooling was subjected to meta-analysis to estimate the odds ratio (OR) and 95% confidence intervals (CI) with a fixed effect model by the Cochrane Collaboration Review Manager (Rev Man, Version 5). Risk estimates of OR and 95% CI were calculated for dichotomous data. The heterogeneity between studies was analyzed using Cochran’s Q test and I2. Pre-specified subgroup analysis was evaluated according to the materials used (all-ceramic & metal-ceramic).Statistical analyses were performed with statistical software (Comprehensive Meta Analysis® version 2.0). Differences were considered statistically significant at the level of 0.05. Results One thousand and ten articles were screened from the electronic search for possible inclusion in the study. A consensus on the studies to be selected was reached after discussion; 969 articles were excluded on
3
the basis of the title and abstract. The reasons for excluding the articles were as follows; either there was a lack of specific data on cantilever or fixed-fixed RBFDPs, they were; case reports, in vitro or non-clinical studies. Full-text articles were obtained for the 41 selected publications. Hand searches were performed on bibliographies of the selected articles as well as of identified narrative reviews. The hand search did not identify any additional articles that matched the inclusion criteria. Thirty-six articles were excluded from the final analysis, resulting in the inclusion of 5 studies. The reasons for exclusion are listed in Table 2. Only one RCT was included13. With the lack of RCTs, clinical controlled trials, prospective and retrospective cohort studies comparing at least two designs of RBFDP were also included into this study and selected for meta-analysis. Two of the 5 included studies were prospective cohort studies14,19 and two were retrospective cohort studies (Table 3).20,21 Details of methodological characteristics are summarized in Table 4. The assessment of risk of bias is presented in Table 5 and Table 6. The RCT had a high risk of bias since the details of random sequence generation, blinding, and other sources of bias were not clarified in the study. The Newcastle-Ottawa scores of cohort studies ranged from 3 to 4 stars with a high risk of bias. There is no star ranking possible for the comparability, since none of the cohort studies described the baseline control for patient selection. Failure rate Four of the 5 included studies demonstrated a lower failure rate for cantilever RBFDPs.13,14,19,21 The results of estimated failure rate for cantilever RBFDPs and two-retainer fixed-fixed RBFDPs are shown in Fig. 2. Cantilever RBFDPs demonstrated lower failure rates (OR 0.42, 95% CI 0.19 to 0.94, Z = 2.10, P = 0.04). Heterogeneity among studies was not indicated (Q = 6.49, P = 0.17, I2 = 38%). Failure rate of metal-ceramic RBFDPs Metal-ceramic RBFDPs showed no difference of failure rates between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs (OR 0.93, 95% CI 0.33 to 2.63, Z = 0.14, P = 0.89, Fig. 3). Heterogeneity among studies was not observed (Q = 0.77, P = 0.68, I2 = 0%, Fig. 3). Failure rate of all ceramic RBFDPs All ceramic RBFDPs showed 10-year failure rate of 26.1% in the two-retainer fixed-fixed group and 5.6% in the cantilever group, which was not statistically significant.14 Two two-retainer fixed-fixed RBFDPs lost bond, and one retainer of a two-retainer fixed-fixed RBFDP fractured in another included study (N = 10), whereas no cantilever RBFDP failed.19 No meta-analysis was conducted in this study, as only two studies were included. Debonding rate Three studies reported no debonding of cantilever RBFDPs,13,14,19 whereas one reported no debonding in two-retainer fixed-fixed RBFDPs.14 No difference between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs as shown in Fig. 4 (OR 0.61, 95% CI 0.23 to 1.60, Z = 1.00, P = 0.32). Heterogeneity among studies was not observed (Q = 2.59, P = 0.46, I2 = 0%).
4
Debonding rate of metal-ceramic RBFDPs Three studies using metal-ceramic RBFDPs showed no difference of debonding between cantilever RBFDPs and two-retainer fixed-fixed RBFDPs in Fig. 5 (OR 0.81, 95% CI 0.28 to 2.34, Z = 0.39, P = 0.70,).13,20,21 Heterogeneity among studies was not indicated (Q = 1.09, P = 0.58, I2 = 0%, Fig. 5). Debonding rate of all ceramic RBFDPs No debonding was found in two RBFDPs designs in the study of 10-year all-ceramic RBFDPs.14 In Zhou’s study, two two-retainer fixed-fixed RBFDPs and none of cantilever RBFDPs lost bond, but no statistical analysis was conducted. 19 No meta-analysis was conducted, as only two studies were included. Due to the limited studies included, meta-regression could not be performed to evaluate the influence between different factors such as prostheses materials, luting cements, and retention of tooth preparation.
Discussion The results of this meta analysis suggest that cantilever RBFDPs have better survival rates compared to two-retainer fixed-fixed RBFDPs, which is in contrast to one previous study that found two-retainer fixed-fixed RBFDPs had a better prognosis at 48 and 60 months survival rate of 71% as compared to cantilever RBFDPs with 61% survival.21 Other studies, however, reveal better survival rates with cantilever than with fixed-fixed RBFDPs.22,23 According to other clinical trials, two-unit cantilever RBFDPs perform as well as or even better than 3-unit two-retainer fixed-fixed RBFDPs.24,25 The main reason for the higher failure rate of two-retainer fixed-fixed RBFDPs appears to be the mobility and differential movement of the abutment teeth during function, especially during protrusive and lateral movements under tooth contact, and the rigid connection with the two mobile elements. For the cantilever RBFDP, however, the pontic always moves with the abutment tooth, which limits shear and torque forces on the pontics and connectors.14 This result has been supported by in vitro research in which cantilever RBFDPs demonstrated a significantly higher bond strength than fixed-fixed framework designs after a fatigue test of 12000 load cycles.26 For other multi-retainer RBFDPs, a 75% survival rate was reported for frameworks with 2 to 5 retainers.27 There is no evidence that multiple retainers improve longevity of resin-bonded prostheses. In light of the fact that RBFDPs are applied as a minimally invasive treatment option, one may argue that, based on this evidence, the preferred framework design should be the cantilever design as it requires preparation of only one abutment tooth. No meta-analysis was conducted for all-ceramic in this study. In Kern and Zhou’s study, all-ceramic RBFDPs are more likely to fracture at the connector areas, which increase the failure probability of the prostheses. Hot-pressed casting ceramic (IPS Empress and IPS e.max Press) demonstrated a survival rate of 100% after 1 year and a 88.5% after 3 years follow-up for RBFDPs in the anterior region.19,22 The limited flexural strength and toughness of these silicate ceramics requires that recommended connector dimensions, which have to be larger as compared to ceramics with greater strength. Cantilever RBFDPs made from glass-infiltrated ceramic In-Ceram zirconia (containing about 26% zirconia) resulted in 94.4% survival rate in a long-term study with 10 years follow up.14 However, connector fracture is not the common failure for metal-ceramic RBFDPs.28 No significant difference between cantilever and fixed-fixed design for
5
metal-ceramic RBFDPs was detected. Fiber-reinforced composite RBFDPs have favorable esthetic outcomes but may not provide sufficient strength. This material can only be used with a two-retained fixed-fixed RBFDP design.29 A medium observation time of 5 years of fiber-reinforced composite RBFDPs shows 75-77% survival rates.27,30 As concluded in a literature review of different materials for RBFDPs, the most frequent complications were debonding for metal-ceramic RBFDPs, fracture for all-ceramic RBFDPs, and delamination of the composite veneering material for the fiber-reinforced composite rstorations.31 Proper, enamel-preserving tooth preparation may influence retention of RBFDPs. Preparation designs with or without retention form varied among the studies reported. Within this meta-analysis, only one study reported tooth preparation with retention form.13 Two studies reported tooth preparation without retention form and only lingual rests to allow a defined insertion of the restoration during bonding.14,19 Two studies did not identify the type of tooth preparation due to them being retrospective study designs.20,21 Tooth preparation with retention forms, such as proximal boxes, grooves, and pin holes, were suggested to enhance the survival rate for RBFDPs.32 In contrast, survival rate of cantilever RBFDPs without retention form of tooth preparation showed a favorable result of 93.1% after 5-year follow-up. Tooth preparation might not need retention forms with the use of resin cements, but a lingual rest to ensure the accurate seating of the RBFDP is universally recomended.8 However, due to the small sample size of existing clinical data, conclusions should be drawn carefully. The survival of RBFDP restorations seems to rely on the resin bond and not on any additional mechanical retention. Clinical outcomes with RBFDPs using either Panavia 21 TC (Kuraray, Kurashiki, Japan) or Multilink-Automix bonding system (Ivoclar Vivadent, Schaan, Liechtenstein) did not differ within the first 5 years.8 In case of metal-ceramic RBFDP, congruous results were observed when comparing Panavia F (Kuraray, Osaka, Japan) and Super-Bond C&B (Sun medical, Moriyama, Japan).9 Thus, different resin cements might not have an influence on the risk of failure for RBFDP in clinical practice.33 To ensure a dry working area, the use of a rubber dam is recommended. Two studies applied rubber-dam, whereas one study applied cotton rolls, and one study applied both rubber-dam and cotton roll for controlling saliva contamination.13,14,19,20,21 Cases applied with rubber-dam reported less incidence of debonding than the ones with cotton rolls only.20 Therefore, rubber-dam application appears to be positively correlated to the survival of RBFDPs.34 Air-particle abrasion provided better retention for metal-framework RBFDPs.13,21 Similarly, long-term bond strength studies to glass-infiltrated ceramics was greatly affected by surface treatment.35 The preferred surface treatment methods include, tribochemical silica coating and silanization (Rocatec, 3M ESPE, Seefeld, Germany) of the alumina ceramic, followed by application of a phosphate-monomer-containing composite resin.36 Air-particle abrasion with 50 μm alumina particles at 1.0-2.5 bar and use of a phosphate-monomer-containing composite resin luting agent are preferred bonding methods.37,38 As 10-methacryloyloxydecyldihydrogenphosphate (MDP) forms a water-resistant chemical bond with zirconia, MDP-containing resin cement is a popular choice for luting zirconia prostheses in clinical
6
applications.23 Moreover, application of a MDP-containing priming agent to the air-particle abraded surface has been shown to significantly enhance bond strengths of composite-resin luting agents to zirconia.39,40 In a prospective study, cantilever single-retainer CAD/CAM fabricated zirconia RBFDPs present an alternative treatment option, offering good esthetics, a minimally invasive preparation, high biocompatibility, and of most importance, a 100% survival rate of with no fracture occurrence after 5 years.41 However, there is lack of clinical trials comparing CAD/CAM fabricated two-retainer fixed-fixed RBFDPs and cantilever single-retainer RBFDPs, and more further investigations are needed. The evidence presented and currently available relates to the data mainly from prospective and retrospective cohort studies, as there is a lack of RCTs available, which may be due to widespread concerns about cantilever FDP designs.42 The methodological assessment of included studies was not satisfactory. Among the included studies, the RCT did not specifically clarify randomisation methods and blindness, resulting in a potential selection and detection bias, consequently the quality of evidence from this study was very low. None of the cohort studies provided comparability, which resulted in low Newcastle-Ottawa scales and low evidence level grading. Additionally, abstracts of grey articles and articles published in other languages were not followed up, which might result in selection bias. Therefore, when interpreting the results it should be born in mind that the evidence level has been weakened by the poor quality control, and well designed RCTs with large sample size are still needed.
Conclusions Based on the results of mainly cohort studies, because of the lack of high quality RCTs, cantilever RBFDPs demonstrate lower clinical failure than two-retainer RBFDPs in the anterior region. The failure of metal-ceramic RBFDPs is independent of the framework design, while the failure of all-ceramic RBFDPs with different designs has not been clear yet.
Acknowledgements The authors would like to express their gratitude for assistance from the Chinese Evidence-Based Medicine Center. They would also like to thank Prof. Matthias Kern (Department of Prosthodontics, Christian-Albrechts University, Kiel, Germany) and Dr. Tuan-feng Zhou (Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China) for the additional data from their clinical trials.
7
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www.cochrane-handbook.org. 19. Zhou TF, Wang XZ, Zhang GR. All-ceramic resin bonded fixed partial denture made of IPS hot-pressed casting porcelain restore anterior missing teeth: a three years clinical observation. Journal of Peking University (Health Sciences) 2011;43:77-80. 20. Garnett MJ, Wassell RW, Jepson NJ, Nohl FS. Survival of resin-bonded bridgework provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors. British Dental Journal 2006;201: 525,527-34. 21. Chai J, Chu FC, Newsome PR, Chow TW. Retrospective survival analysis of 3-unit fixed-fixed and 2-unit cantilevered fixed partial dentures. Journal of Oral Rehabilitation 2005;32:759-65. 22. Zhang L, Nie YG, Xie QF. Clinical application of anterior all-ceramic cantilevered resin-bonded fixed partial dentures. Chinese Journal of Stomatology 2008;43:209-11. 23. Creugers NH, Snoek PA, Van 't Hof MA, Käyser AF. Clinical performance of resin-bonded bridges: a 5-year prospective study. Part III: Failure characteristics and survival after rebonding. Journal of Oral Rehabilitation 1990;17:179-86. 24. Chan AW, Barnes IE. A prospective study of cantilever resin-bonded bridges: an initial report. Australian Dental Journal 2000;45:31-6. 25. Djemal S, Setchell D, King P, Wickens J. Long-term survival characteristics of 832 resin-retained bridges and splints provided in a post-graduate teaching hospital between 1978 and 1993. Journal of Oral Rehabilitation 1999;26:302-20. 26. Wong TL, Botelho MG. The fatigue bond strength of fixed-fixed versus cantilever resin-bonded partial fixed dental prostheses. Journal of Prosthetic Dentistry 2014;111:136-41. 27. Vallittu PK. Survival rates of resin-bonded, glass fiber-reinforced composite fixed partial dentures with a mean follow-up of 42 months: a pilot study. Journal of Prosthetic Dentistry 2004;91:241-6. 28. Hussey DL, Pagni C, Linden GJ. Performance of 400 adhesive bridges fitted in a restorative dentistry department. Journal of Dentistry 1991;19:221-5. 29. Burke FJ. Resin-retained bridges: fiber-reinforced versus metal. Dental Update 2008;35:521-2, 524-6. 30. van Heumen CC, Tanner J, van Dijken JW, Pikaar R, Lassila LV, Creugers NH, et al. Five-year survival of 3-unit fiber-reinforced composite fixed partial dentures in the posterior area. Dental Materials 2010;26:954-60. 31. Miettinen M, Millar BJ. A review of the success and failure characteristics of resin-bonded bridges. British Dental Journal 2013;215:E3. 32. Behr M, Leibrock A, Stich W, Rammelsberg P, Rosentritt M, Handel G. Adhesive-fixed partial dentures in anterior and posterior areas: results of an on-going prospective study begun in 1985. Clinical Oral Investigations 1998;2:31-5. 33. Hussey DL, Linden GJ. The clinical performance of cantilevered resin-bonded bridgework. Journal of Dentistry 1996;24:251-6.
9
34. Creugers NHJ, De Kanter RJAM, Verzijden CWGJM, Van’t Hof MA. Risk factors and multiple failures in posterior resin-bonded bridges in a 5-year multi-practice clinical trial. Journal of Dentistry 1998;26:397-402. 35. Kern M, Thompson VP. Bonding to a glass infiltrated alumina ceramic: Adhesion methods and their durability. Journal of Prosthetic Dentistry 1995;73:240-9. 36. van Dalen A, Feilzer AJ, Kleverlaan CJ. The influence of surface treatment and luting cement on in vitro behavior of two-unit cantilever resin-bonded bridges. Dental Materials 2005;21:625-32. 37. Blatz MB, Sadan A, Kern M. Resin-ceramic bonding: a review of the literature. Journal of Prosthetic Dentistry 2003;89:268-74. 38. Wegner SM, Kern M. Long-term resin bond strength to zirconia ceramic. Journal of Adhesive Dentistry 2000;2:139-47. 39. Blatz MB, Chiche G, Holst S, Sadan A. Influence of surface treatment and simulated aging on bond strengths of luting agents to zirconia. Quintessence International 2007;38:745-53. 40. Tanaka R, Fujishima A, Shibata Y, Manabe A, Miyazaki T. Cooperation of phosphate monomer and silica modification on zirconia. Journal of Dental Research 2008;87:666-70. 41. Sasse M, Kern M. CAD/CAM single retainer zirconia-ceramic resin-bonded fixed dental prostheses: clinical outcome after 5 years. International Journal of Computerized Dentistry 2013;16:109-18. 42. Walls AW. Cantilever FPDs have lower success rates than end abutted FPDs after 10-year of follow-up. Journal of Evidence Based Dental Practice 2010;10:41-3.
10
Fig. 1 - Results of the article search
11
Fig. 2 - Results of meta-analysis for failure rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
12
Fig. 3 - Metal-ceramic results of meta-analysis for failure rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
13
Fig. 4 - Results of meta-analysis for debonding rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
14
Fig. 5 - Metal-ceramic results of meta-analysis for debonding rate of two-retainer fixed-fixed vs. cantilever RBFDP designs
15
Table 1 - Inclusion and exclusion criteria Inclusion Criteria Type of study
Type of patients (P) Type of interventions (I) Type of control (C) Type of outcomes (O) Exclusion Criteria Type of study Type of interventions Follow-up time Outcomes
Randomized-controlled clinical trials (RCTs) Prospective or retrospective cohort studies; Clinical controlled trials (CCT) (when lack of RCTs) Anterior teeth missing patients treated by RBFDPs Anterior teeth missing patients treated by cantilever RBFDPs Anterior teeth missing patients treated by two-retainer fixed-fixed RBFDPs in the same study Reporting the details of mechanical or biological complications incidence Case reports, case series, animal studies and in-vitro studies Not including cantilever or fixed-fixed resin-bonded fixed dental prosthesis Less than 2 years No detailed clinical outcomes but only questionnaire and survey follow-up Multiple publications on the same patient cohorts.
16
Table 2 - Number of studies excluded with regard to each exclusion criteria Exclusion Criteria
Number of studies
Not reporting designs of resin-bonded fixed partial dentures
24
Multiple publications on the same patient cohort
3
Follow-up time less than 2 years
2
No clinical visit follow-up, only questionnaire and survey follow-up
7
17
Table 3 - Study and patient characteristics of the included studies Mean follow-up
Study
Year
Study design
Kern et al.14
2011
Prospective cohort study
111
38
Not reported
0
Zhou et al.19
2011
Prospective cohort study
41.3
26
>18
0
Garnett et al.20
2006
Retrospective cohort study
59.3
71
11 ~ 43
Not reported
Chai et al.21
2005
Retrospective cohort study
47
33
Not reported
Not reported
Chan et al.13
2000
34
25
15~56
Randomized controlled trial
time (month)
18
No. of prostheses
Age range
Drop out
0
Table 4 - Methodological characteristics of included studies Manufacturing Procedure Study
Prosthesis design
Location
Material In Ceram
Kern et al.14†
cantilever =22 fixed-fixed =16
Anterior
Alumina In Ceram
Clinical Considerations
Surface treatment
Tooth preparation
Isolation method
Failures Bonding system
Debond
Fracture
cantilever =0
1
fixed-fixed =0
6
cantilever =0
0
fixed-fixed =2
1
cantilever =25
0
fixed-fixed =3
0
cantilever =2
0
fixed-fixed =3
0
cantilever =0
0
fixed-fixed =1
0
A lingual veneer, a groove
Tribochemically silica coated and silanated
on the cingulum, a small proximal box (2mm x
Rubber-dam
Panavia TC
Cotton roll
Variolink II
1mm x 0.5mm)
Zirconia Zhou et al.19†
Garnett et al.20
21
Chai et al.
Chan et al.
†
cantilever =16 fixed-fixed =10 cantilever =62 fixed-fixed =9
cantilever =18 fixed-fixed =15
13
cantilever =13 fixed-fixed =12
Anterior
Anterior
IPS Empress E.max Metal-ceramic
2% HF 60s
No retention form
Not reported
Not reported
Air-abraded Anterior
Metal-ceramic
50μm
Rubber-dam used in 6 bridges only
Panavia
with
alumina
Not reported
Not reported
Panavia
Rubber-dam
Panavia
particles
Gritblasted Anterior
Metal-ceramic
50μm
with alumina
particles
Some with retention form (proximal
grooves
additional rests)
Detailed information was collected by personal communication with the corresponding author via email.
19
and
Table 5 - Quality assessment of the included studies with the Newcastle-Ottawa Scale
Coding Manual for Cohort Studies Kern et al.
14
Zhou et al.19
Garnett et al.20
SELECTION 1) Representativeness of the exposed cohort 2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale SELECTION 1) Representativeness of the exposed cohort 2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale SELECTION 1) Representativeness of the exposed cohort
20
Newcastle-Ottawa Scale d c a★ a★
a★ a★ a★ ★★★★★ d c a★ a★
a★ b a★ ★★★★ d
Chai et al.21
2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale SELECTION 1) Representativeness of the exposed cohort 2) Selection of the non-exposed cohort 3) Ascertainment of exposure 4) Demonstration that outcome of interest was not present at start of study COMPARABILITY 1) Comparability of cohorts on the basis of the design or analysis OUTCOME 1) Assessment of outcome 2) Was follow-up long enough for outcomes to occur 3) Adequacy of follow up of cohorts Total Scale
21
c a★ b
a★ a★ d ★★★ d c a★ b
a★ b d ★★
Table 6 - Quality assessment of the included study with Cochrane Handbook for Systematic Reviews of Interventions Study
Chan et al.13
Random sequence
Allocation
generation
concealment
Unclear
Unclear
Blinding
Data
Selective report
integrity Unclear
22
Adequate
Other sources of bias
Adequate
Yes