in case of excessive amounts being claimed (i.e., excessive extra billing).

Third, selective underwriting and risk rating could be used to counteract adverse selection and to protect existing clients against free riders who abuse the insurance system. Providing insurance for pre-existing conditions is incompatible with the insurance principle that only future, unforeseen risks can be covered: a burning house cannot be insured.

Fourth, applying waiting times for expensive treatments such as prosthetics and providing only limited coverage during the initial years of the contract constitute alternatives to a general limitation of coverage. For instance, in Germany, limited coverage typically applies during the first 4 years of the insurance contract.

Fifth, behavioral economics aspects such as liquidity constraints and debt aversion could be dealt with by offering a combination of optimal dental insurance in combination with a health (dental) savings account. The dental savings account could be used to finance trivial costs. In this way, CDI could be optimized and would not be tainted by attempts to also cover trivial risks. Ignorance and social comparison can be taken care of by improving the transparency of CDI products. Consumer organizations can play an important role in clarifying the market offer for the consumer.

The authors wish to thank Richard Burton and Seraf Van Den Bosch for their corrections and suggestions.


Cells without complete genomes {#s1}
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Cells have long been recognized as life\'s building blocks (e.g., Virchow\'s dictum "*omnis cellula e cellula*," Virchow, [@B31]). Specifically, a cell\'s genome is considered the repository of genetic information that pairs with the cellular machinery to determine the organism\'s phenotype. Except for rare circumstances, the majority of a genome is passed on from ancestor to descendant, although the acquisition of genes from organisms that are not direct ancestors is recognized to play an important role in evolution (Swith