88 prospective, clinical trials (1996–2015) were analyzed in terms of survival of posterior composite restorations.
Significant findings were only observed for short-term studies and by including all studies (short- and long-term studies).
The observation period, the recall rate, the ratio of Class I/II fillings and the number of restorations/patients had a significant influence on the overall failure rate when including all studies (short- and long-term).
No influence of operator status, isolation method or bonding systems on the overall failure rate was found.
In this study a trend of excluding patients at-risk (e.g. high caries activity) and including patients with good oral hygiene was identified, which produces more favorable results.
The aim of this study is to analyze the survival of posterior composite restorations published within the last 19 years (1996–2015).
In this study only prospective, clinical trials with specification of the failure rate according to Class I/II composite fillings were included. Studies were analyzed according to the observation period (all studies vs. short-term vs. long-term studies). Retrospective studies and/or open laminate studies, tunnel restorations and Class V restorations were excluded. The following variables possibly influencing the failure rate were extracted from the studies: observation period, recall rate, average age of patients, number of patients, ratio of Class I/II fillings, number of restorations, ratio of premolars/molars, operator, method of isolation, bonding generation and filler size.
A total of 88 studies were included for statistical analysis. The observation period of the studies varied between 1 and 17 years, while most of the studies did not last longer than 5 years. Fracture of the restorations, secondary caries and marginal gap are the main causes for failure in the first 5 years (in descending order), while fracture and secondary caries are similarly distributed in long-term studies. Variables of investigation differed greatly in significance according to the respective observation period. The observation period, the recall rate, the ratio of Class I/II fillings and the number of restorations and patients had a significant influence on the overall failure rate when including all studies (short- and long-term). A linear correlation between the observation period and the failure rate was observed. In long-term studies these variables were not significant any longer. No significant difference in the failure rates between the materials per study was observed. The most common commercial composites investigated were: Tetric Ceram, Surefil, Filtek Supreme (incl. XT), Filtek Z250.
The mean annual failure rate was 1.46% (±1.74%) for short-term studies and 1.97% (±1.53) for long-term studies.
There is still a big need for clinical studies lasting longer than 5 years, as failure rates of composite restorations in posterior teeth increases with longer observation periods.
A decreasing failure rate with an increasing recall rate as observed in our study suggests a patient selection in regard to availability and dental awareness. Internationally standardized evaluation criteria are mandatory in order to allow comparisons of the outcomes of clinical studies.
Dental composite restorations have been increasingly used for posterior restorations in the past few years. At the same time amalgam has become less popular due to its “black” metallic appearance and biocompatibility concerns. The time required for the restoration of posterior cavities with composite materials may reach twice the time compared to restoring these cavities with amalgam . Therefore most manufacturers developed new generations of adhesive systems in order to reduce the time (and steps) during bonding and so-called “bulk-fill” composites .
Initially, composite as a filling material for posterior restorations was reserved for small cavities, but as a decline of amalgam’s popularity, it is also used for large (multi-surface) restorations . Different clinical studies investigating its performance in posterior teeth reported varying annual failure rates of 0–9.0% (mean: 2.2%) including comparable failure rates of 0–7.4% for amalgam (mean: 3%) .
In 2003, Brunthaler et al. published a review of prospective studies (1996–2002) investigating the clinical performance of direct posterior resin composites. Main reasons for restoration failure were fracture followed by secondary caries in the first 5 years. Operator, method of isolation (rubber dam/cotton rolls), bonding generation and packability of the composite did not show a significant influence on failure rates. However, conventional composites (in contrast to hybrid composites), Class II fillings and the observation period had a significant influence on the occurrence of a failure. Since 2003 three further studies reviewing the literature in terms of longevity of direct composite restorations have been published: Manhart et al. reported a mean annual failure rate of 2.2% for direct composite restorations in posterior teeth. Heintze and Rousson conducted a meta-analysis of the clinical effectiveness of direct Class II restorations including amalgam, composite and compomer restorations (59 studies). Amalgam and composite showed a similar overall success rate of about 90% after 10 years. They calculated a median failure rate of about 8% for resin composites after 10 years (excluding compomers). Demarco et al. analysed studies (from 1996 to 2011) on posterior composite restorations with a study period of at least 5 years. They reported annual failure rates between 1% and 3% for Class I and Class II restorations in 90% of these studies.
Retrospective cross-sectional studies published in the last few years also report a decreasing use of amalgam: Rho et al. compared the longevity of amalgam and resin composite restorations placed in 140 patients involving Class I and Class II cavities. The restorations were placed between 1986 and 2008 in Seoul, South Korea . In this study, the first record of a direct posterior composite restoration was found in 1996. After 2003 the proportion of composite was already superior to that of amalgam. The median survival times were 8.7 (amalgam) and 5.0 (composite) years. Another retrospective study reported about the longevity of large Class II amalgam and composite restorations placed in 273 patients between 1983 and 2003 in the Netherlands . Similar to the aforementioned study , before 1994 these restorations were mainly performed with amalgam, while after 1995 amalgam was no longer used. But this study indicates a higher survival time for composite than amalgam after 12 years (AFR = 1.68% vs. AFR = 2.41%). Sunnegårdh-Grönberg et al. reported a median longevity of replaced restorations for resin based composite, glass ionomer cement and amalgam of 6, 11 and 16 years, respectively, for northern Sweden . Composite as a filling material was used in 93% of all first restorations due to primary caries and in 89% of all replaced restorations. The use of amalgam was negligible (less than 1%), especially in the last decade.
In Norway , the longevity of 4030 Class II restorations in 1873 patients was observed using a prospective, practice-based study design . Resin composite was the most used filling material (i.e. 81.5%) among 27 participating dentists from the clinics of the Public Dental Health Service. In contrast, only 4.6% of all restorations were restored with amalgam. However, amalgam had a significantly better survival rate.
The superior use of resin-based composites over amalgam has also been observed in the US . This trend toward composite was also taken into consideration by the teaching in dental schools .
Some studies reported a lower , similar/comparable or even better performance for amalgam compared to resin composite as a filling material for posterior teeth, but there is an inevitably trend toward minimal restorative dentistry focusing on a preservation of a maximum of sound tooth tissue. This is best accomplished with adhesively bonded resin composite materials and therefore recommended by the Academy of Operative Dentistry European Section (AODES) .
The aims of this study were to review all published studies between 1996 and 2015 on the clinical performance of composite in posterior teeth and to compare the different failure rates and modes to those presented by Brunthaler et al. 12 years later.