Inter- and intra-examiner variability in scoring supragingival plaque: II. Statistical analysis

Area of Science:

• Dentistry
• Oral Hygiene
• Clinical Measurement

Background:

• Accurate assessment of supragingival plaque is crucial for effective oral hygiene and periodontal health management.
• The Turesky modification of the Quigley-Hein plaque index is a commonly used method for quantifying plaque levels.
• Understanding variability in plaque scoring is essential for reliable clinical trials and patient care.

Purpose of the Study:

• To assess inter- and intra-examiner variability in scoring supragingival plaque using the Turesky modification of the Quigley-Hein method.
• To determine if professional background (dentist vs. dental hygienist) or experience level influences scoring consistency.
• To identify the primary sources of extraneous variation in plaque scoring.

Main Methods:

• Four examiners (dentists and dental hygienists with varying experience) each assessed plaque scores for 24 patients on two separate occasions.
• Data were analyzed to evaluate mean scores, score variability, and precision between and within examiners.
• Statistical analysis was employed to identify sources of measurement error and examiner-related variations.

Main Results:

• No significant systematic differences were found between dentists and dental hygienists in their mean, variability, or precision of plaque scores.
• Similarly, examiner experience did not correlate with systematic differences in scoring outcomes.
• Major sources of extraneous variation included measurement error, inter-examiner variability unrelated to training/experience, and inconsistent application of scoring criteria.

Conclusions:

• The Turesky modification of the Quigley-Hein method demonstrated considerable variability in supragingival plaque scoring.
• Factors beyond professional background and experience, such as measurement error and inconsistent criterion application, significantly impact scoring reliability.
• Standardization of training and clear application guidelines are recommended to improve the consistency of plaque index scoring in clinical practice.