This study aimed to (1)record the plaque and gingival status on sound
and carious approximal surfaces and (2) investigate whether the two pa
rameters could predict approximal lesion progression. For this purpose
two samples were selected among 18- to 25-year-old patients at the De
ntal Faculty in Copenhagen. Sample 1 consisted of 45 patients, each ha
ving an approximal posterior surface requiring operative treatment and
a contralateral approximal space, where both surfaces were radiograph
ically sound. Sample 2 consisted of 25 patients, each having a posteri
or approximal tooth surface with an enamel/initial dentinal lesion rec
orded on a bitewing. Plaque and gingival status were classified using
4-point ranked scales, The recordings were performed once on each part
icipant in sample 1. The recordings in sample 2 were repeated 5 times
during a 15-month period, In order to assess lesion progression in sam
ple 2, two serial intraoral examinations were performed, i.e. at the b
eginning and end of the study. Less than 10% of the sound and carious
surfaces were recorded as plaque-free, while about 40% had a thick or
heavy plaque accumulation. No significant difference was observed betw
een plaque scores on sound and carious surfaces (p = 0.5), in contrast
to findings representing the gingival status (p<0.001). Tooth surface
s requiring operative treatment were associated with bleeding of the g
ingiva after probing. In sample 2, 3 of the 25 participants did not fi
nish the study. On the remaining participants caries progression was o
bserved in 9 cases (41%), while no progression was observed in 13 case
s. Analyses showed that there were no significant differences between
plaque scores in cases with caries progression, as compared with no ca
ries progression (p>0.05), Similar analyses concerning gingival status
showed that bleeding of the gingiva was related to cases with progres
sing caries. Analyses also disclosed no direct association between pla
que and gingival status (Spearman correlation coefficient 0.39). Thus,
the occurrence of plaque does not have the same predictive power as b
leeding after probing in decision-malting as to whether or not a lesio
n progresses.