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International Poster Journal of Dentistry and Oral Medicine



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Int Poster J Dent Oral Med 10 (2008), No. 3     15. Sep. 2008

Int Poster J Dent Oral Med 2008, Vol No , Poster 420

Reliability of plaque and gingivitis parameters in different study populations - An experimental ginivitis study

Language: English

Dr. Gerlinde Bruhn, Dr. Katrin Lorenz, Prof. Dr. Michel Brecx, PD Dr. Lutz Netuschil, Prof. Dr.Thomas Hoffmann,
Poliklinik für Zahnerhaltung, Bereich Parodontologie, Technische Universität Dresden
PD Dr. Christian Heumann,
Institut für Statistik, Ludwig-Maximilians-Universität München

June 29, 30 and July 1, 2006
EuroPerio 5
Madrid, Spain


Several indices are recognized as reliable for scoring plaque and gingivitis during evaluation of mechanical as well as chemotherapeutic antiplaque procedures. The aim of this investigation was to determine the correlation between two established plaque index systems and between plaque indices and gingivitis indices in a randomized, clinical controlled experimental gingivitis study of mouthrinses.

Material and Methods

Study design:
A 21-day experimental gingivitis study was performed. After a recruiting period the participants were randomly assigned to a mouthrinse group. During these 21 days no other oral hygiene measures than the rinsing were permitted.

Study populations:
Three study populations were selected depending on the oral hygiene level of the participants at the recruiting visit.
Population A: 39 dental students with excellent oral hygiene (PlI ≤ 0.5)
Population B: 38 participants from a local population with average oral hygiene (PlI ≥ 1.0)
Population C: 77 participants of a mixed population regardless the oral hygiene level

Plaque index (PII, Silness & Löe 1964)
Plaque index (QHI, Turesky mod. Quigley & Hein 1970)
Gingival index (GI, Löe et al. 1967)
Modified gingival index (MGI, Lobene et al. 1986)

Chlorhexidine digluconate 0.20%

Pearson correlation coefficient (p≤0.05)


In all three populations statistically significant correlations were found between the two plaque indices PlI and QHI. Between plaque recording systems and gingivitis parameters GI and MGI a correlation existed in population A. No correlation could be observed in the placebo-groups in population B and C.

Placebo 0.20 % CHX Placebo 0.20 % CHX Placebo 0.20 % CHX
PlI-QHI 0.539* 0.658* PlI-QHI 0.861* 0.872* PlI-QHI 0.680* 0.809*
PlI-GI 0.608* 0.656* PlI-GI -0.090 0.595* PlI-GI 0.291 0.538*
PlI-MGI 0.631* 0.584* PlI-MGI 0.580 0.614* PlI-MGI 0.368* 0.556*
QHI-GI 0.540* 0.660* QHI-GI -0.055 0.734* QHI-GI 0.257 0.515*
QHI-MGI 0.487* 0.567* QHI-MGI 0.022 0.733* QHI-MGI 0.265 0.554*
Table 1: Population A; Pearson correlation coefficients ( n=39,* sign. p<0.05)
Table 2: Population B; Pearson correlation coefficients ( n=38,* sign. p<0.05)
Table 3: Population C; Pearson correlation coefficients (n=77,* sign. p<0.05)
Fig. 1: Population A; Correlation between PlI - QHI, Placebo (p=0.014) Fig. 3: Population B; Correlation between PlI - QHI, Placebo (p≤0.000) Fig. 5: Population C; Correlation between PlI - QHI, Placebo (p≤0.000)
Fig. 2: Population A; Correlation between PlI - GI, Placebo (p=0.004)
Fig. 4: Population B; Correlation between PlI - GI, Placebo (p=0.090)
Fig. 6: Population C; Correlation between PlI - GI, Placebo (p=0.291)


The plaque accumulation can be estimated effectively by the plaque indices PlI and QHI in each group and population. The high plaque-levels in the placebo-groups of populations B and C did not correlate with increase of gingivits.

The study was supported by GABA International AG.


CHX = Chlorhexidine
PlI = Plaque index
QHI = Plaque index, modified
GI = Gingivitis index
MGI = Gingivitis index, modified

This Poster was submitted by Dr. Gerlinde Bruhn.

Correspondence address:
Dr. Gerlinde Bruhn
Technische Universität Dresden
Poliklinik für Zahnerhaltung, Bereich Parodontologie
Fetscherstraße 74
01307 Dresden
Phone: +49 (0)351 4582712