A 7-year-old has deep caries on tooth K involving the mesial, occlusal and lingual surfaces. What is the best restoration?

Correct answer: D. Stainless steel crown

• A. Extraction of a restorable second primary molar creates a significant space maintenance problem, since it is the tooth that maintains the leeway space.
• B. Composite is technique-sensitive, requires good isolation, and performs poorly in large multi-surface primary molar restorations.
• C. A multi-surface amalgam in a primary molar has a high failure rate; the remaining tooth structure after preparation is inadequate to support it.
• D. CORRECT. A multi-surface lesion in a primary molar is the classic indication for a stainless steel crown. Full-coverage restorations in primary molars have markedly higher longevity and lower failure rates than multi-surface intracoronal restorations, and tooth K — the mandibular left second primary molar — needs to survive until roughly age 11 or 12.

Note: The AAPD position is explicit: full-coverage stainless steel crowns are indicated for multi-surface lesions, after pulp therapy, for developmental defects, and in high-caries-risk children. Note also that tooth K is the SECOND primary molar — losing it before the first permanent molar has erupted and established causes mesial drift and loss of arch length that is very difficult to recover.