What do systematic reviews say?

Preformed crown (any material; conventional technique or Hall Technique) vs Filling (any material; with or without complete carious tissue excavation; with or without pulp treatment)

Preformed crown (any material; conventional technique or Hall… showed no clear difference in adverse events: gingival bleeding compared with filling (any material; with or without complete carious tissue…; GRADE not reported.

• Preformed crowns for decayed primary molar teeth 2015 · Cochrane All outcomes

  Short term (up to 12 months)
  RR 1.69 [0.61, 4.66]
  2 studies · 226 participants
  GRADE not reported
• Preformed crowns for decayed primary molar teeth 2015 · Cochrane All outcomes

  Long term (12 months)
  RR 1.74 [0.99, 3.06]
  2 studies · 195 participants
  Low

Hall technique vs Non-restorative caries treatment

It is very uncertain whether preformed metal crown (fitted using the Hall Technique) changes adverse events: gingival bleeding compared with non-restorative caries treatment (very low certainty).

• Preformed crowns for decayed primary molar teeth 2015 · Cochrane All outcomes

  Long term (12 months)
  RR 1.09 [0.42, 2.86]
  1 study · 92 participants
  Very low

Preformed metal crown (stainless steel), conventional technique vs Aesthetic crown (stainless steel with composite/white veneer), conventional technique

• Preformed crowns for decayed primary molar teeth 2015 · Cochrane All outcomes

  Six months and four years
  At six months, none (0/11) of the PMC sites had gingival bleeding, but all (11/11) veneer sites had bleeding, 10 of which bled on probing; statistically significant (McNemar's test, P < 0.001). At four years, one case…
  1 study · 11 participants
  Very low