Which to choose: complete vs. incomplete caries removal? A Systematic Review
This summary is based on the article published in the Journal of Dental Research : Incomplete caries removal: a systematic review and meta-analysis (April 2013)
Context
For nearly a century, dental caries has been treated by attempted eradication: Bacteria and all infected dental biomass (1) were removed, and the resulting cavity was subsequently restored. As knowledge and attitudes concerning the dental biofilm and pathogenesis of caries changed, the common treatment procedure for caries lesions was questioned as well. (2)
The complete removal of all carious tooth substance from cavitated lesions is no longer seen as mandatory, and there is growing evidence supporting incomplete removal of carious tissue before the cavity is restored. (4) Theoretically, it is argued, a completely sealed remaining caries lesion should be arrested. Hence, therapy of cavitated lesions may require less focus on complete excavation than on adequate restorations (5, 2)
Purpose of the Review
The aim was to systematically review randomized controlled trials investigating one- or two-step incomplete compared with complete caries removal. Studies treating primary and permanent teeth with primary caries lesions requiring a restoration were analyzed.
The following primary and secondary outcomes were investigated: risk of pulpal exposure, post-operative pulpal symptoms, overall failure, and caries progression.
Key Findings
- Incomplete caries removal seems advantageous, particularly in the treatment of caries in proximity to the pulp, since it significantly reduces the risks of pulpal exposure and post-operative pulpal symptoms compared with complete excavation.
- Effect estimates showed considerable reduction of pulp exposure and post-operative pulpal complications for incomplete excavation compared with complete caries removal.
- Risk of total failure, after exclusion of teeth with exposed pulps, was similar for incompletely and completely excavated teeth.
- It remains unclear whether leaving more carious dentin may be beneficial (fewer pulp exposures and symptoms) or detrimental (higher risk of failure and caries progression).
- There is currently no evidence that incompletely excavated teeth are more prone to complications. However, because of high risk of bias within studies, evidence levels are limited, and further research is required before definitive conclusions can be drawn.
References
- Fusayama T, Okuse K, Hosoda H (1966). Relationship between hardness, discoloration, and microbial invasion in carious dentin. J Dent Res 45:1033-1046.
- Kidd EA (2004). How ‘clean’ must a cavity be before restoration? Caries Res 38:305-313.
- Kidd EA, Fejerskov O (2004). What constitutes dental caries? Histopathology of carious enamel and dentin related to the action of cariogenic biofilms. J Dent Res 83(Spec No.C):C35-C38.
- Banerjee A, Watson TF, Kidd EA (2001). Dentine caries: take it or leave it? S Afr Dent J 56:189-192.
- Ricketts D (2001). Restorative dentistry: management of the deep carious lesion and the vital pulp dentine complex. Br Dent J 191:606-610.
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I am a bit concerned that a posting like this can lead young clinicians to believe that they do not need to be diligent to remove (enough) decay prior to restoration placement. ‘Enough’ is placed in brackets as there has been research for decades which show bacteria present in dentinal tubules even after the most stringent clinical decay removal. The studies referenced were mainly concerned with this aspect and the dangers of iatrogenic pulp exposures during caries removal.
It would be helpful to add that magnification with operating microscopes almost eliminates the incidence of iatrogenic pulp exposure. Significant soft decay can still remain after clinicians have inspected the preparation with low mag loupes. Soft decay will undermine the bonding of composites and provide an area of flex under the restoration (so all of the all-amalgam crew can be worried too!).
It should still be reinforced that decay removal of structurally unsound material be removed, especially at the margins (as these studies indicate) but also within the base area. A movement toward the use of microscopes should be favored rather than leaving structurally unsound material in for fear of ‘going too far’.
Significant decay left under a restoration should be reserved only for those situations where you KNOW you can’t go further without having an iatrogenic exposure, where the tooth is vital/normal or slightly cold sensitive to pulp tests, and where you know that you will be going in within two years to remove the rest of the decay once secondary buildup is evident.
I appreciate what this posting is trying to accomplish. However, while it is true that a practitioner can leave infected dentin under a properly sealed restoration, it is also true that being too timid will cause the patient harm in the long-term. The operating microscope will not only improve the results a dentist will get every time, it will also help with the decision of what to leave and what to take out with no doubt whatsoever.
As my undergraduate training comes from the time when leaving any caries under restorations was unacceptable, I would agree that removing it all would be the best option. However, in view of the new studies if not removing it all can save the patient a root canal treatment complication and resulting full coverage of the tooth, it would appear to be a rather conservative approach. As for the magnification issue, I am sure that a ten times magnification may show more than telescopes, however, in my opinion stating that using the microscope will remove any doubt whatsoever about how much caries to remove is more than optimistic. I have been practising for many years and have seen many treatments performed very well eventually failing, I have also seen treatments appearing mediocre and serving the patient for many years. I have learned that I would not have the courage to ever say that I have no doubts whatsoever.