Chairside evaluation of pH-lowering activity and lactic acid production of dental plaque: correlation with caries experience and incidence in preschool children.
OBJECTIVE
Because caries activity may be related to dental plaque acidogenicity, a method was developed for chairside evaluation of pH-lowering activity and lactic acid production by dental plaque. Moreover, this study examined the association of these 2 factors with caries experience on oral examination and with caries activity by following caries incidence for 4 years in a group of preschool children.


METHODS
A dental plaque sample (2.4 microL) was collected from sound buccal surfaces of maxillary primary second molars using a spoon excavator and placed onto the sensor area of a portable pH meter. Sucrose (30 microL, 228 mmol) was mixed with the plaque sample, and pH changes were monitored for 10 minutes. After pH determination, lactic acid concentration in the plaque-sucrose mixture was measured using a portable lactate meter.


RESULTS
Caries experience of subjects correlated with minimum pH (at 10 minutes after sucrose addition) ( r = -0.53, P < .001) and lactic acid production ( r = 0.38, P < .001). In addition, increments of both primary tooth caries (Delta dft) and permanent tooth caries (Delta DFT) for 4 years correlated with minimum pH ( r = -0.47, P < .005 and r = -0.38, P < .05, respectively). Setting cutoff values of pH and lactic acid concentration at 5.0 and 7.0 mmol/L for DELTA dft allows screening for caries-susceptible subjects (sensitivity = 0.950 and 0.800, specificity = 0.391 and 0.783, respectively).


CONCLUSIONS
Plaque in caries-susceptible preschool children displays greater pH-lowering activity and lactic acid production. This method can be applied as a chairside screening test for caries activity and susceptibility for preschool children in dental clinics.
Shimizu
Koichi
K
Shimizu Pediatric Dental Clinic, Shizuoka, Shizuoka Prefecture, Japan.
Igarashi
Koei
K
Takahashi
Nobuhiro
N
D002675:Child, Preschool; D004245:DMF Index; D003731:Dental Caries / Q000145:classification; D003732:Dental Caries Activity Tests; D003733:Dental Caries Susceptibility; D003773:Dental Plaque / Q000737:chemistry* / Q000378:metabolism; D005500:Follow-Up Studies; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000032:analysis*; D008963:Molar / Q000473:pathology; D009911:Oral Hygiene Index; D019095:Point-of-Care Systems; D012680:Sensitivity and Specificity; D013395:Sucrose / Q000378:metabolism; D014094:Tooth, Deciduous / Q000473:pathology
D019344:Lactic Acid; D013395:Sucrose