Experimental Study on Strength Evaluation Applied for Teeth Extraction: An In Vivo Study

PURPOSE: The aim of this work was to analyse all the applied movements when extracting healthy upper and lower jaw premolars for orthodontic purposes. The authors wanted to demonstrate that the different bone densities of the mandible and maxilla are not a significant parameter when related to the extraction force applied. The buccal and palatal rocking movements, plus the twisting movements were also measured in this in-vivo study during premolar extraction for orthodontic purposes. METHODS: The physical strains or forces transferred onto the teeth during extraction are the following three movements: gripping, twisting, and traction. A strain measurement gauge was attached onto an ordinary dentistry plier. The strain measurement gauge was constituted with an extensimetric washer with three 45º grids. The system operation was correlated to the variation of electrical resistance. RESULTS: The variations of resistance (∆R) and all the different forces applied to the teeth (∆V) were recorded by a computerized system. Data results were processed through Microsoft Excel. The results underlined the stress distribution on the extracted teeth during gripping, twisting and flexion. CONCLUSIONS: The obtained data showed that the strength required to effect teeth extraction is not influenced by the quality of the bone but is instead influenced by the shape of the tooth’s root.