Sir, deep carious lesions are challenging with regard to selecting a restorative treatment method which preserves pulp vitality. In recent years the treatment trend has changed from traditional complete caries removal to stepwise excavation (SE), partial caries removal (PCR) and no caries removal (NCR) modalities.

Clinical trials carried out in this field have shown several shortcomings questioning the validity of the study: application of calcium hydroxide as the common liner, restoration of the teeth with different restorative materials in a single trial, and including both permanent and primary teeth in a single study are among some of the confounding variables that may be responsible for the lower validity or bias of some trials. Some of these issues were also pointed out recently by the Cochrane Database Systematic Review.

In the last two decades biomaterials have been introduced in dentistry. In spite of the advances in this area, it is surprising that none of the studies on deep carious lesions assessed the application of new biomaterials such as MTA and Biodentine which could have higher antibacterial activity, biocompatibility and sealing ability than calcium hydroxide, which is applied as a common liner in SE or PCR.

According to the results of a clinical trial we have carried out, the application of biomaterials or 'bio-treatment of deep carious lesions' can be considered as an effective method to restore the involved tooth both biologically and functionally with long-term pulp vitality. We encourage dental researchers and professionals to establish guidelines to conduct high quality clinical trials and introduce a scientific, reliable and valid method to dentists for bio-treatment of deep caries.