The authors regret that Figures 3, 4, 5, 6, and 7 contained graphs that should have been corrected to box-and-whisker plots since the statistics were done in nonparametric form. The figures, figure legends, and the accompanying Results section is printed here in its entirety.
Fig. 3.
Body tilt angle: occlusal surface cavity preparation.
During the occlusal cavity preparation, the direct view technique produced a significantly larger body tilt at the angles of the parietal to the seventh cervical vertebra and the seventh cervical vertebra to the first lumbar vertebra. In the box-and-whisker diagram, upper whisker = maximum, lower whisker = minimum, the top edge of the box = upper quartile, the center of the box = median, and the bottom edge of the box = lower quartile (n = 10).
Fig. 4.
Body tilt angle: adjacent tooth preparation of the distal axial surface.
During the preparation of the distal surface of the adjacent tooth, the direct view technique produced a significantly larger body tilt at the angles of the parietal to the seventh cervical vertebra and the seventh cervical vertebra to the first lumbar vertebra.
Fig. 5.
Muscle activity: occlusal surface cavity preparation.
During occlusal cavity preparation, the direct view technique resulted in significantly greater activities of the right and left trapezius muscles and the right spinal column erector muscle than the mirror view technique. However, the left spinal column erector muscle showed no significant difference.
Fig. 6.
Muscle activity: adjacent tooth preparation of the distal axial surface.
During the preparation of the distal surface of the adjacent tooth, the direct view technique produced significantly greater activities in the right and left trapezius muscles and the right spinal column erector muscle and the spinal column erector muscles. However, the left spinal column erector muscle showed no significant difference.
Fig. 7.
Right and left balance of sitting pressure.
During the preparation of the occlusal cavity and the distal surface of the adjacent tooth, the direct view technique produced significantly larger pressures than the mirror view technique.
Results
At the occlusal cavity preparation, body tilt of the parietal to the seventh cervical vertebra showed a median of 70.4° (third quartile = 78.3°, first quartile = 64.2°) with the direct view technique and 35.4° (third quartile = 40.7°, first quartile = 31.2°) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 3, left). Body tilt of the seventh cervical vertebra to the first lumbar vertebra showed a median angle of 17.6° (third quartile = 22.1°, first quartile = 14.1°) with the direct view technique and 2.4° (third quartile = 4.6°, first quartile = 1.1°) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 3, right).
At the distal surface of the adjacent tooth preparation, body tilt of the parietal to the seventh cervical vertebra showed a median of 68.5° (third quartile = 75.6°, first quartile = 62.1°) with the direct view technique and 39.3° (third quartile = 43.8°, first quartile = 33.6°) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 4, left). Body tilt of the seventh cervical vertebra to the first lumbar vertebra showed a median angle of 18.3° (third quartile = 33.0°, first quartile = 14.3°) with the direct view technique and 4.0° (third quartile = 6.0°, first quartile = 0.8°) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 4, right).
At the occlusal cavity preparation, muscle activity of the right trapezius muscle showed a median of 0.090 mV/s (third quartile = 0.127 mV/s, first quartile = 0.078 mV/s) with the direct view technique and 0.077 mV/s (third quartile = 0.088 mV/s, first quartile = 0.055 mV/s) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 5, upper left). Muscle activity of the left trapezius muscle showed a median angle of 0.089 mV/s (third quartile = 0.127 mV/s, first quartile = 0.074 mV/s) with the direct view technique and 0.060 mV/s (third quartile = 0.071 mV/s, first quartile = 0.052 mV/s) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 5, upper right).
At the occlusal cavity preparation, muscle activity of the right spinal column standing muscle showed a median of 0.084mV/s (third quartile = 0.108mV/s, first quartile = 0.069 mV/s) with the direct view technique and 0.065 mV/s (third quartile = 0.074 mV/s, first quartile = 0.057 mV/s) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 5, lower left). Muscle activity of the left spinal column standing muscle showed a median angle of 0.078 mV/s (third quartile = 0.101 mV/s, first quartile = 0.062 mV/s) with the direct view technique and 0.71 mV/s (third quartile = 0.080 mV/s, first quartile = 0.062 mV/s) with the mirror view technique. No significant difference was observed between the direct view technique and the mirror view technique (Figure 5, lower right).
At the distal surface of the adjacent tooth preparation, muscle activity of the right trapezius muscle showed a median of 0.117 mV/s (third quartile = 0.209 mV/s, first quartile = 0.087 mV/s) with the direct view technique and 0.084 mV/s (third quartile = 0.112 mV/s, first quartile = 0.063 mV/s) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 6, upper left). Muscle activity of the left trapezius muscle showed a median angle of 0.087 mV/s (third quartile = 0.126 mV/s, first quartile = 0.062 mV/s) with the direct view technique and 0.076 mV/s (third quartile = 0.089 mV/s, first quartile = 0.064 mV/s) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 6, upper right).
At the distal surface of the adjacent tooth preparation, muscle activity of the right spinal column standing muscle showed a median of 0.68 mV/s (third quartile = 0.087 mV/s, first quartile = 0.062 mV/s) with the direct view technique and 0.062 mV/s (third quartile = 0.069 mV/s, first quartile = 0.057 mV/s) with the mirror view technique. Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 6, lower left). And muscle activity of the left spinal column standing muscle showed a median angle of 0.072 mV/s (third quartile = 0.088 mV/s, first quartile = 0.057 mV/s) with the direct view technique and 0.072 mV/s (third quartile = 0.085 mV/s, first quartile = 0.064 mV/s) with the mirror view technique. No significant difference was observed between the direct view technique and the mirror view technique (Figure 6, lower right).
Regarding the right and left balance of sitting pressure; at the occlusal cavity preparation, the direct view technique showed a median of 535.0 mm Hg (third quartile = 660.3 mm Hg, first quartile = 351.5 mm Hg) and the mirror view technique showed 226.0 mm Hg (third quartile = 337.0 mm Hg, first quartile = 75.8 mm Hg). Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 7, left). At the distal surface of the adjacent tooth preparation, the direct view technique showed a median of 567.5 mm Hg (third quartile = 976.5 mm Hg, first quartile = 345.0 mm Hg) and the mirror view technique showed 285.5 mm Hg (third quartile = 366.5 mm Hg, first quartile = 189.3 mm Hg). Significantly larger values were observed with the direct view technique than the mirror view technique (Figure 7, right).