Pulpitis induction in baboon primary teeth using carious dentine or Streptococcus mutans.

The objective of this equivalency study was to see if a colony of Streptococcus mutans placed into cavities in primary molar teeth produced pulpitis similar to an established pulpitis induction method using carious dentine. In two juvenile baboons (Papio ursinus), occlusal cavities were cut in all 16 primary molar teeth, followed by making a small pulpal exposure after which the cavity was swabbed with 37 per cent phosphoric acid. In one half of the teeth, fresh soft human carious dentine was placed over the pulpal exposure; in the remaining teeth the exposure was covered with a colony of Streptococcus mutans in agar. All the cavities were restored with unlined light-cured composite resin. After 14 days specimens were harvested and examined under the light microscope with the examiner blind to the induction method. In both groups of teeth there was recognisable pulp, hyperaemia, micro-abscesses in the pulp and peri-apical abscesses. Reactions to soft caries were more severe than to Streptococcus mutans. The results show that Streptococcus mutans placed in a cavity with an exposure produces comparable pulpitis to fresh soft human carious dentine in the same type of cavity and that both methods produce pulpitis suitable for testing pulpotomy or pulpectomy treatments.