In-Vitro Measurement of Forces During Debridement with a Piezoelectric Ultrasonic Periodontal Scaler

Abstract

Purpose: This study investigated the magnitude, direction, and temporal aspects of the force applied during instrumentation with a piezoelectric ultrasonic periodontal scaler, compared this force with recommendations in the literature, and assessed the influence of the profession (dentist or dental hygienist) and calculus hardness.

Materials and methods: The force applied by ten dental hygienists and six dentists during debridement of comparatively soft and hard artificial dental calculus with a piezoelectric ultrasonic scaler was recorded in-vitro. The total force and its components in three axes were statistically analysed.

Results: During debridement of soft artificial dental calculus, the mean total force applied by dental hygienists was 0.34 N (± 0.18 N, range: 0.13 N to 0.59 N) and by dentists 0.28 N (± 0.33 N, range: 0.06 N to 0.95 N), and the total force exceeded 0.5 N approximately 23% and 14% of the time for dental hygienists and dentists, respectively. During debridement of hard artificial dental calculus, the mean total force applied by dental hygienists was 0.63 N (± 0.40 N, range: 0.28 N to 1.64 N) and by dentists 0.57 N (± 0.17 N, range: 0.34 N to 0.76 N); the total force exceeded 0.5 N more than half of the time for both professions. On average, dental hygienists applied 1.85x (p = 0.04) and dentists 2.04x (p = 0.06) higher force on hard than on soft artificial calculus. However, dental hygienists and dentists used similar forces during the debridement of both hard (p = 1.00) and soft (p = 0.26) calculus.

Conclusion: The force applied during the debridement of hard artificial dental calculus was statistically significantly higher than during the debridement of soft artificial dental calculus. No statistically significant difference between dentists and dental hygienists was found. The force applied by both groups on soft and hard artificial dental calculus frequently exceeded recommended values.

Keywords: calculus; debridement; periodontal; piezoelectric; ultrasonic.

Fig 1

Image taken during debridement (top left) using the measurement set-up (center): base plate (1); three-axis force sensor (2) with amplifier (3); data acquisition module (4); Model A (5) with comparatively soft and Model B (6) with comparatively hard artificial dental calculus; adapters (7), handrest (8); and piezoelectric ultrasonic scaler (9) and definition of coordinate system aligned to Model A and Model B (bottom).

Fig 2

Sections of the total force (F_tot) and its components (Fx, Fy, and Fz) measured during the debridement of Model B by two dental hygienists exemplarily illustrating two different working patterns.

Fig 3

Scatter plots and linear regressions of the force component parallel (√[Fx² + Fz²]) and perpendicular (Fy) to the surface of the calculus model measured during debridement of Model A (a) and Model B (b) by dental hygienists and dentists.

Fig 4

Average distributions of total force (F_tot) applied by dentists and dental hygienists during debridement of Model A (a) and Model B (b). The relative number of instances of forces exceeding 2 N is not shown.

Fig 5

Average distributions of the rate of change of the total force (|dF_tot/dt|) applied by dental hygienists and dentists during debridement of Model A (a) and Model B (b). The relative number of changes exceeding 10 N/s is not shown.