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The implant design with the shorter smooth coronal collar had no additional bone loss and may help to reduce the risk of an exposed metal implant margin in areas of esthetic concern.

Yeasts can be detected in 7–18% of infected root canals. They are commonly associated with persistent cases of apical periodontitis, but yeasts can also be isolated in primary apical periodontitis. Their relative proportion of the root canal flora is low, usually below 1%. Therefore, yeast detection with conventional microbiological methods may be difficult. Selective culture media such as Sabouraud dextrose agar combined with cultivation from undiluted sample should be used for primary isolation of yeasts in endodontic infections. Preliminary identification of yeasts is based on typical colony and cellular morphology and a positive catalase test. Detection by molecular biological methods is sensitive, but may occasionally also give false‐positive results. Candida albicans is the most commonly detected yeast species from infected root canals. It is typically found together with Gram‐positive bacteria such as streptococci, but can also be isolated in pure culture, which is an indication of its pathogenicity. A variety of virulence factors enable C. albicans to adhere to and penetrate into dentine. Furthermore, C. albicans tolerates harsh ecological conditions including high alkalinity. Calcium hydroxide is generally not efficient against oral yeasts in vitro; the in vivo effectiveness of calcium hydroxide is not known. However, sodium hypochlorite, iodine compounds, and chlorhexidine have proven effective against yeasts both in experimental conditions as well as in vivo and may offer effective treatment possibilities against endodontic yeast infections.

EcoR124 and EcoDXXI are allelic type I restriction‐modification (R‐M) systems whose specificity genes consist of common structural elements: two variable regions are separated by a constant, homologous region containing a number of repetitive sequence elements. In vitro recombination of variable and constant elements has led to fully active, hybrid R‐M systems exhibiting new and predictable target site specificities. Methylation of synthetic DNA sequences with purified, hybrid modification methylases was used to confirm the proposed recognition sequences. The results clearly demonstrate the correlation between protein domains and target site specificity. Our data suggest that a bacterial population may switch the recognition sequences of its type I R‐M system by single recombination events and thus is able to maintain a prokaryotic analogue of the immune system of variable specificity.