23 February 2023

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Universal materials and selective procedures in restorative dentistry – where are we now?

Lorenzo Breschi

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The current trend in the dental industry is to provide universal materials in the form of a one bottle system that can be used in a variety of clinical situations. Manufacturers claim that these systems are more user-friendly, since they require less chair-side time and can tolerate potential mistakes during adhesive procedures without jeopardizing retention of composite restorations. 

These systems all claim to be reliable, since they should perform as equally well as gold standard materials which have been available on the market for several decades and have a long track of follow-up period. The two most recent examples of these materials are universal adhesive systems and universal self-adhesive resin cements. 

Even though they are considered to be universal, we now know that the clinical performance of composite restorations placed with universal adhesives in non-carious cervical lesions (NCCLs) is largely dependent on the application mode (etch-and rinse [EAR], self-etch [SE] or selective-enamel etch [SEE]), thus questioning the true “versatility” of universal adhesives.  

For example, higher retention rates are achieved when a universal adhesive is applied in EAR or SEE mode, while the risk of post-operative sensitivity can be reduced to minimum when they are used in SE and SEE mode. The longest follow-up period from randomized controlled clinical trials (RCTs) of these materials is approximately five years, which is much less compared to gold standard adhesives (follow up > 20 years). As far as universal self-adhesive resin cements are concerned, evidence about their performance from RCTs and real-world data are still missing, while the data from laboratory studies supporting the good properties of these cements are increasing.

The most common selective procedure in restorative dentistry concerns the decision to completely or partially remove dentinal caries. Traditionally, dental caries were completely removed, which was often associated with reduction of dental tissues and weakened tooth structure and endodontic treatment. Therefore, selective and stepwise removal techniques were suggested. Selective removal involves excavating carious tissue to achieve hard enamel and dentin at the peripheries of the lesion while leaving soft or firm carious dentin in the deepest part of the cavity close to pulp. 

Stepwise removal involves selective removal of carious tissue and provisional restoration placement. Six to 12 months later, the provisional restoration and carious tissue are removed followed by placement of a definitive composite restoration. The International Caries Consensus Collaboration has said that there is no need to remove bacterially contaminated or demineralized tissues close to the pulp. 

In teeth with deeper lesions and vital pulps, preserving pulpal health should be prioritized. In primary and permanent teeth with deep lesions, selective removal of carious tissue should be performed (strong recommendation). In permanent teeth with deep lesions, stepwise removal might also be an option (strong recommendation). 

Selective use of cavity liners and bases was often considered in dental school in the past, and some dentists still use it today in the deepest part of cavities. Today we know that there is no sufficient evidence to recommend cavity lining before placing composite restorations. 

Considering what I’ve shared above, we can say that the decision-making process in every day dental practice regarding the use of universal materials and common selective procedures in restorative dentistry should be based on firm evidence from (preferably) long-track RCTs and carefully conducted systematic reviews. In the last few years, we can definitely observe a great tendency in shifting to universal systems and preservation of tooth vitality by contemporary adhesive procedures.