A systematic review and meta analysis of the longevity of anterior and posterior all-ceramic crowns

Abstract

Background

Clinical experience suggests that there is a difference in survival between anterior and posterior all ceramic restorations.

Objectives

This systematic review compared the difference in survival for full coverage all-ceramic materials used in adults to restore anterior or posterior vital teeth, not involved with fixed dental prostheses, but opposed by teeth.

Data and sources

Searches using Medline, Embase, and the Cochrane Library, including hand searches, with the inclusion criteria containing all-ceramic full coverage crowns in human adults over 17 years of age, prospective and retrospective studies, opposed by teeth, periodontal pocketing ≤5 mm, but not involving implant supported crowns or non-vital teeth. All papers were published between 1980 and March 2014 and available in English. From the selected studies a meta analysis was undertaken. The chi square test, I 2 , Begg’s and Egger’s test were analysed and the publication bias was assessed using a Funnel plot. The, Kappa scores were 0.63, 0.88, and 0.81 at each selection stage.

Study selections

Pooled data produced 1112 anterior crowns with 73 failures (6.5%) and 1821 posterior crowns with 166 failures (9.1%) with a follow up time from 36 to 223 months. Relative risk meta-analysis of the 14 selected papers demonstrated that anterior all-ceramic crowns were 50% less likely to fail than posterior all-ceramic crowns (p = 0.001).

Conclusion

These results indicate that there were differences in failure between anterior and posterior all ceramic crowns but the difference was only 3%. Although this has clinical relevance and some caution is needed when prescribing all ceramic posterior crowns the difference was relatively small.

Clinical significance

The clinically relevant results of this review, based on currently available data, demonstrate a need for some caution when considering posterior all-ceramic crowns. Lithium disilicate restorations were observed to have higher failures on anterior restorations and more research is needed to investigate why.

Introduction

Ceramic materials are used to restore teeth, including the provision of conventional tooth supported single crowns. All-ceramic crowns are considered favourable in the anterior dentition compared to metal-ceramic and metal crowns due to their aesthetic qualities . However, there is a debate over the appropriate use of these materials in the posterior dentition.

A direct comparison of the longevity of anterior and posterior all-ceramic crowns has not been made prior to this study . Four of these systematic reviews reported some data on the differences between anterior and posterior crowns, but focused on fracture rates and survival of all types of crowns. Wasserman et al. , reported the outcome of In-Ceram crowns, in a pseudo systematic review and within this paper three studies contained data comparing anterior to posterior crowns. From these, Scherrer et al. reported, in a retrospective clinical trial, that a ‘clear’ difference was observed in the fracture of anterior (2% of 45 crowns) and posterior (13% of 23 crowns) for In-Ceram Alumina crowns over a five-year period. McLaren and White , reported 3 year survival rates of 98% for anterior crowns and 94% for posterior crowns, and Segal in another clinical study, reported higher survival rates of posterior crowns (99.2%) compared to anterior crowns (98.9%).

Three other systematic reviews report partial data on the outcome for anterior and posterior all-ceramic crowns . Wang et al. , reported the core or veneer annual fracture rates for all ceramic crowns over 3 years and observed statistically significant differences (p = 0.001) between anterior (0.6%) and posterior (1.1%) core fractures but not for veneer fractures. Heintze and Rousson reviewed fracture rates of leucite-based all-ceramic crowns (Empress™) and observed statistical differences in the higher fracture rates for molar (6.7%) and canine (2.9%) crowns compared to premolars (2.9%) and incisor (2.3%) crowns. Pjetursson et al. reported the 5-year survival of all-ceramic crowns compared to metal ceramic crowns. These authors subdivided all-ceramic crowns into four material groups, with all showing higher annual fracture rates on posterior teeth and statistical differences observed in glass-ceramics (p = 0.008) and InCeram™ (p = 0.028).

Despite these data there remain questions on the longevity and outcome of all-ceramic materials used to restore posterior teeth irrespective of material and cause of failure. The aim of this review was to compare the difference in longevity for any all-ceramic material used to restore anterior and posterior teeth, not involved with fixed dental prostheses or posts.

Methods – eligibility and search strategy

Medline, EMBASE and the Cochrane library bibliographic databases were searched electronically. Two searches, were conducted on each database, and combined. The first search, used keywords linked to Medical Subject Headings (MeSH) and indicated as follows, (1) ‘ceramics’ (MeSH); (2) ‘dental ceramic’; (3) searches (1) and (2) combined with ‘or’; (4) ‘tooth crown’ (MeSH); (5) ‘crowns’ (MeSH); (6) ‘tooth crown* or crown* or dental crown*’; (7) searches (4), (5) and (6) combined with ‘or’; (8) searches (3) and (7) combined with ‘and’. The second search used keywords, (1) ‘dental porcelain’ (MeSH); (2) ‘dental porcelain* or dental laminate*’; (3) searches (1) and (2) combined with ‘or’; (4) ‘tooth crown’ (MeSH); (5) ‘crowns’ (MeSH); (6) ‘tooth crown* or crown* or dental crown*’; (7) searches (4), (5) and (6) combined with ‘or’; (8) searches (3) and (7) combined with ‘and’. Following this, the searches were combined with the primary outcomes. Manual hand searches were subsequently conducted through the Prosthodontic literature using the International Journal of Prosthodontics, the International Journal of Computerized Dentistry, the Journal of Oral and Maxillofacial Implants, and the Journal of Prosthodontics. “Grey literature” was also searched on OpenSIGLE ( opensigle.insit.fr ) and the Web of Science. These searches were complemented by communications with various authors and manufacturers of ceramic materials. All the articles were pooled and duplicates removed.

The inclusion criteria were reports containing all-ceramic full coverage crowns in human adults over 17 years of age, using clinical, randomized controlled trials, prospective and retrospective studies in situations where the restored teeth were opposed by teeth, periodontal pocketing ≤5 mm, but not involving implant supported crowns or non-vital teeth. All papers were published between 1980 and March 2014 and available in English. Exclusion criteria, included laboratory studies, opinion-based articles, ceramic crowns used with fixed dental prostheses, partial coverage crowns, single case reports and abstract reports.

Data collection

The titles were independently screened at different times by two of the authors. Where there was doubt or lack of agreement the titles were discussed and a decision made as to whether to include or exclude the articles. Cohen’s Kappa coefficient was calculated to measure inter-reviewer agreement at each stage. Where abstracts or full papers were not available the article was excluded.

Analysis

Given the variation between the studies, and lack of volume of directly comparable data available, the studies were assessed at a binary level of success or failure. Failure included any event that affected the crown, examples being chipping, fracture, caries, loss of the crown, whereas, success recorded no adverse events. Where data were not clear, or if only anterior or posterior crowns were individually reported, these papers were excluded. Anterior crowns were defined from canine to canine and remaining teeth were classified as posterior restorations. The binary data allowed comparative analysis of crowns using relative risk meta-analysis. The inequality in the lengths of the studies complicated direct comparison between studies. Therefore, similar length studies were analaysed in sub-groups using mean follow-up periods of 3 and 4 years (group 1), 5 and 6 years (group 2) and 7 or more years (group 3).

Descriptive statistics were used to summarise the study characteristics and relative risk meta analysis carried out using the ‘metan’ command in stata (Data Analysis and Statistical software, version 12, Stata corp, USA). To account for study variations, random effects models were used in the meta-analysis, for both within and between study variations in effect sizes. Relative risk of failure of anterior crowns compared to posterior crowns and the 95% confidence interval were calculated separately for each study. The chi square test was used to assess for heterogeneity in the data beyond the value of chance and the percentage of heterogeneity in the data were calculated using the heterogeneity measure I 2 . Bias due to small study effects were assessed using Begg’s and Egger’s test and publication bias assessed visually using a Funnel plot drawn using ‘metafunnel’ command in stata.

Methods – eligibility and search strategy

Medline, EMBASE and the Cochrane library bibliographic databases were searched electronically. Two searches, were conducted on each database, and combined. The first search, used keywords linked to Medical Subject Headings (MeSH) and indicated as follows, (1) ‘ceramics’ (MeSH); (2) ‘dental ceramic’; (3) searches (1) and (2) combined with ‘or’; (4) ‘tooth crown’ (MeSH); (5) ‘crowns’ (MeSH); (6) ‘tooth crown* or crown* or dental crown*’; (7) searches (4), (5) and (6) combined with ‘or’; (8) searches (3) and (7) combined with ‘and’. The second search used keywords, (1) ‘dental porcelain’ (MeSH); (2) ‘dental porcelain* or dental laminate*’; (3) searches (1) and (2) combined with ‘or’; (4) ‘tooth crown’ (MeSH); (5) ‘crowns’ (MeSH); (6) ‘tooth crown* or crown* or dental crown*’; (7) searches (4), (5) and (6) combined with ‘or’; (8) searches (3) and (7) combined with ‘and’. Following this, the searches were combined with the primary outcomes. Manual hand searches were subsequently conducted through the Prosthodontic literature using the International Journal of Prosthodontics, the International Journal of Computerized Dentistry, the Journal of Oral and Maxillofacial Implants, and the Journal of Prosthodontics. “Grey literature” was also searched on OpenSIGLE ( opensigle.insit.fr ) and the Web of Science. These searches were complemented by communications with various authors and manufacturers of ceramic materials. All the articles were pooled and duplicates removed.

The inclusion criteria were reports containing all-ceramic full coverage crowns in human adults over 17 years of age, using clinical, randomized controlled trials, prospective and retrospective studies in situations where the restored teeth were opposed by teeth, periodontal pocketing ≤5 mm, but not involving implant supported crowns or non-vital teeth. All papers were published between 1980 and March 2014 and available in English. Exclusion criteria, included laboratory studies, opinion-based articles, ceramic crowns used with fixed dental prostheses, partial coverage crowns, single case reports and abstract reports.

Data collection

The titles were independently screened at different times by two of the authors. Where there was doubt or lack of agreement the titles were discussed and a decision made as to whether to include or exclude the articles. Cohen’s Kappa coefficient was calculated to measure inter-reviewer agreement at each stage. Where abstracts or full papers were not available the article was excluded.

Analysis

Given the variation between the studies, and lack of volume of directly comparable data available, the studies were assessed at a binary level of success or failure. Failure included any event that affected the crown, examples being chipping, fracture, caries, loss of the crown, whereas, success recorded no adverse events. Where data were not clear, or if only anterior or posterior crowns were individually reported, these papers were excluded. Anterior crowns were defined from canine to canine and remaining teeth were classified as posterior restorations. The binary data allowed comparative analysis of crowns using relative risk meta-analysis. The inequality in the lengths of the studies complicated direct comparison between studies. Therefore, similar length studies were analaysed in sub-groups using mean follow-up periods of 3 and 4 years (group 1), 5 and 6 years (group 2) and 7 or more years (group 3).

Descriptive statistics were used to summarise the study characteristics and relative risk meta analysis carried out using the ‘metan’ command in stata (Data Analysis and Statistical software, version 12, Stata corp, USA). To account for study variations, random effects models were used in the meta-analysis, for both within and between study variations in effect sizes. Relative risk of failure of anterior crowns compared to posterior crowns and the 95% confidence interval were calculated separately for each study. The chi square test was used to assess for heterogeneity in the data beyond the value of chance and the percentage of heterogeneity in the data were calculated using the heterogeneity measure I 2 . Bias due to small study effects were assessed using Begg’s and Egger’s test and publication bias assessed visually using a Funnel plot drawn using ‘metafunnel’ command in stata.

Results

A total of 3937 articles were obtained from the initial title searches ( Fig. 1 and Table 1 ). On applying the inclusion and exclusion criteria these were reduced to 320 abstracts with a Kappa score of 0.68 (95% Confidence Interval (95% CI) 0.63–0.73). The abstracts were reduced to 119 full articles, with a Kappa score of 0.88 (95% CI 0.83–0.94) and finally 14 papers selected for data analysis, with a Kappa score 0.81 (95% CI 0.70–0.91) consisting of 9 prospective and 5 retrospective studies.

Fig. 1
Flow chart of the study selection.

Table 1
The 14 studies selected for meta-analysis.
Study Follow Up Period in Months Group Study Type Material No. Anterior Crowns Anterior Failed (%) No. Posterior Crowns Posterior Failed (%)
Scotti 44 1 Prospective Slip Cast Alumina core (Inceram) 25 0 (0) 38 1 (2.6)
Probster 56 1 Prospective Slip cast alumina core (Inceram) 28 1 (3.6) 67 2 (3)
Haselton 36 1 Retrospective Slip cast alumina core (Inceram) 43 1 (2.3) 67 2 (3)
Sorensen 36 1 Retrospective Leucite reinforced glass ceramic (Empress) 47 0 (0) 28 1 (3.6)
Oden 60 2 Prospective Pure alumina core (Allceram) 17 0 (0) 83 9 (10.8)
Segal 72 2 Prospective Slip cast alumina core (Inceram) 117 2 (1.7) 369 3 (8.1)
Walter 72 2 Prospective Pure alumina core (Allceram) 61 2 (3.3) 46 4 (6.3)
Toksavul 60 2 Prospective Lithia disilicate (Empress II) 56 1 (1.80 23 0 (0)
Kokubo 66 2 Prospective Pure alumina core (Allceram) 37 3 (8.1) 64 9 (14)
Sorrentino 72 2 Retrospective Pure alumina core (Allceram) 74 1 (1.4) 54 5 (9.3)
Kokubo 60 2 Prospective Cad/cam Slip cast alumina core (Inceram) 37 3 (8.1) 64 9 (14.1)
Monaco 60 2 Retrospective Various Zirconia 343 15 (4.4) 789 71 (9)
Rinke 223 3 Retrospective Slip cast alumina core (Inceram) 163 36(2.2) 109 49 (45)
Gehrt 96 3 Prospective Lithia disilcate (E.max) 74 8 (10.8) 20 1 (5)
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Jun 19, 2018 | Posted by in General Dentistry | Comments Off on A systematic review and meta analysis of the longevity of anterior and posterior all-ceramic crowns
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