The present investigation was carried out to determine the location of the periodontal probe tip when various loads are applied. Additionally, the role of gingival inflammation to probe resistance was evaluated.The sample consisted of 51 teeth scheduled for extraction. The Gingival Index (GI) was used to establish the degree of inflammation. A loading of 20, 25, 30 ponds was delivered by a spring loaded, sleeve bearing probe fitted with a Michigan 0 probe having a terminal diameter of 0.35 mm. The extracted teeth were fixed and then stained with 4 % toluidine blue. Using a coronal reference groove and the apical margin of the connective tissue attachment (CTA) as reference points apical penetration of the probe was established.The results of this study indicate that there is a linear relationship between the GI and the resistance of the gingival tissues to probe penetration. This is most apparent between a GI = 0 and GI = 3. Whereas with 30 ponds the mean penetration at GI = 0 was 0.30 mm coronal to the CTA, the mean penetration was 1.25 mm apical to the CTA at GI = 3.

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We compare event-cameras with fast (global shutter) frame-cameras experimentally, asking: “What is the application domain, in which an event-camera surpasses a fast frame-camera?” Surprisingly, finding the answer has been difficult. Our methodology was to test event- and frame-cameras on generic computer vision tasks where event-camera advantages should manifest. We used two methods: (1) a controlled, cheap, and easily reproducible experiment (observing a marker on a rotating disk at varying speeds); (2) selecting one challenging practical ballistic experiment (observing a flying bullet having a ground truth provided by an ultra-high-speed expensive frame-camera). The experimental results include sampling/detection rates and position estimation errors as functions of illuminance and motion speed; and the minimum pixel latency of two commercial state-of-the-art event-cameras (ATIS, DVS240). Event-cameras respond more slowly to positive than to negative large and sudden contrast changes. They outperformed a frame-camera in bandwidth efficiency in all our experiments. Both camera types provide comparable position estimation accuracy. The better event-camera was limited by pixel latency when tracking small objects, resulting in motion blur effects. Sensor bandwidth limited the event-camera in object recognition. However, future generations of event-cameras might alleviate bandwidth limitations.

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