Composite resin restorations – incremental or bulk fill?

Composite resin restorations have low reported failure rates of between 1-5% for anterior and posterior teeth. Polymerisation shrinkage and shrinkage stress, polymerisation conversion and depth of cure are considered to be potential challenges and the use of an incremental fill technique may address some of these challenges. However newer bulk-fill materials are now available which have been shown to have similar performance in some studies.

The aim of this review was to compare the clinical effectiveness of bulk-fill versus incrementally layered conventional resin composites and to evaluate if one method offers clear merits with specific clinical outcomes.

Methods

A protocol was registered on the PROSPERO database. Searches were conducted in the PubMed/Medline, Embase, Scopus and the Web of Science databases supplemented by manual searching of the journals, Journal of Esthetic and Restorative Dentistry, Operative Dentistry, and the Journal of Conservative Dentistry. Randomised controlled trials (RCTs) published in English in peer-reviewed journals comparing Class I and Class II direct composite restorations restored by incremental layering technique versus bulk technique were considered. A single reviewer undertook selection, data abstraction and risk of bias assessment using the Cochrane risk-of-bias tool for randomized trials (RoB 2). Owing to the variety of composite materials and bonding systems used, and the differences study designs a narrative summary was presented. Three relevant systematic reviews ^(1-3)were also assessed.

Results

18 studies will follow up time ranging from 6 months to 10 years were included.
2 studies were considered to be at high risk of bias, 2 at low risk with 14 have some concerns.
16 studies used the Modified US Public Health Service assessment criteria.
In both incremental and bulk fill groups tooth- and resin-fractures, followed by secondary caries were the commonest reasons for restoration failure.
Marginal adaptation and staining were discussed along with postoperative sensitivity as were modification of the surface texture and colour stability.
The bulk-fill technique demonstrated no distinction in clinical performance compared to the incremental layering technique.

Conclusions

The authors concluded: –

Bulk filled resin composite restorations demonstrated clinical outcomes similar to those of incrementally layered resin composite restorations within a review interval of 6 months to 10 years.

Comments

This review was part of a thesis project, so study selection was carried out by a single reviewer, and it is unclear whether data abstraction and risk of bias assessment were also carried out by this single reviewer. A protocol was registered on PROSPERO and a good range of databases searched. However as only English language articles were included it is possible that relevant texts were excluded. An assessment of 3 relevant systematic reviews ^(1-3)was included in the paper although a review by Kunz et al (Dental Elf – 16^th Feb 2022) was not. The Kunz review included 14 studies 9 of which were included in this current review and conducted a meta-analysis with their overall findings also suggesting no difference between the two restoration placement techniques. The included studies involved a total of 1951 restoration with all but two of the studies being of a split mouth design. While the split mouth design is efficient appropriate analysis is required. Well designed, conducted and reported studies in a primary care setting with longer follow up periods (only 5 studies reported 4 years or more of follow up) and few variables would be helpful.

Links

Primary Paper

Sengupta A, Naka O, Mehta SB, Banerji S. The clinical performance of bulk-fill versus the incremental layered application of direct resin composite restorations: a systematic review. Evid Based Dent. 2023 Jul 4. doi: 10.1038/s41432-023-00905-4. Epub ahead of print. PMID: 37402908.

Review protocol on PROSPERO

Other references

Arbildo-Vega HI, Lapinska B, Panda S, Lamas-Lara C, Khan AS, Lukomska-Szymanska M. Clinical Effectiveness of Bulk-Fill and Conventional Resin Composite Restorations: Systematic Review and Meta-Analysis. Polymers (Basel). 2020 Aug 10;12(8):1786. doi: 10.3390/polym12081786. PMID: 32785019; PMCID: PMC7464794.
Veloso SRM, Lemos CAA, de Moraes SLD, do Egito Vasconcelos BC, Pellizzer EP, de Melo Monteiro GQ. Clinical performance of bulk-fill and conventional resin composite restorations in posterior teeth: a systematic review and meta-analysis. Clin Oral Investig. 2019 Jan;23(1):221-233. doi: 10.1007/s00784-018-2429-7. Epub 2018 Mar 28. PMID: 29594349.
Cidreira Boaro LC, Pereira Lopes D, de Souza ASC, Lie Nakano E, Ayala Perez MD, Pfeifer CS, Gonçalves F. Clinical performance and chemical-physical properties of bulk fill composites resin -a systematic review and meta-analysis. Dent Mater. 2019 Oct;35(10):e249-e264. doi: 10.1016/j.dental.2019.07.007. Epub 2019 Aug 14. PMID: 31421957.

Dental Elf – 16^th Feb 2022

Composite resin restorations in posterior teeth – incremental or bulk fill?