In the case of a 3-year-old with gross decay in tooth #K, which appliance is best for space maintenance after extraction?

In pediatric dentistry, space maintenance is crucial for maintaining arch integrity and ensuring proper alignment of permanent teeth following the extraction of primary teeth. In the scenario of a 3-year-old with extensive decay in tooth #K, which is a primary mandibular second molar, the best appliance is the distal shoe.

The distal shoe is specifically designed for maintaining space in the posterior mandible following the extraction of primary molars. It is anchored to the adjacent primary teeth and extends distally into the edentulous area where the extracted tooth was located. This design is particularly beneficial for very young children, as it allows for the retention of space for the underlying permanent tooth while also promoting healthy dental arch development.

Other options, such as a lower lingual holding arch or Nance appliance, are generally used in different contexts. The lower lingual holding arch is more suited for maintaining space when more than one tooth needs to be preserved, and the Nance appliance is utilized for maintaining space across the upper arch. A lip bumper, while useful for gaining arch space by encouraging molar eruption, does not directly serve to maintain space after the loss of a primary molar in such a young child.

In summary, the distal shoe is the most appropriate choice in this situation