《口腔医学-牙合学》课件PPT第1章 牙合（英文）.ppt

Optimal Force Magnitude Mandibular movements include laterotrusive and protrusive movements Allows horizontal forces to be placed on teeth Forces are potentially damaging Are some teeth better than others to accept these horizontal forces? Masticatory system is a lever system Similar to a nutcracker More force can be generated closer to the fulcrum Greater force magnitude can be produced closer to the fulcrum (TMJ) Okeson Fig. 5-13 * Optimal Force Magnitude Mandibular movements include laterotrusive and protrusive movements Allows horizontal forces to be placed on teeth Forces are potentially damaging Are some teeth better than others to accept these horizontal forces? Masticatory system is a lever system Similar to a nutcracker More force can be generated closer to the fulcrum Greater force magnitude can be produced closer to the fulcrum (TMJ) Okeson Fig. 5-13 * Optimal Force Magnitude More force can be generated on posterior teeth than on anterior teeth Damaging horizontal forces are best managed by the anterior teeth Which of the anterior teeth are best suited to accept horizontal forces in eccentric movements? Central incisors Lateral incisors Canines Why? Greater force magnitude can be produced closer to the fulcrum (TMJ) Okeson Fig. 5-13 * Optimal Force Magnitude Which of the anterior teeth are best suited to accept horizontal forces in eccentric movements? Canines Why? Longest and largest roots Best crown:root ratio Surrounded by dense compact bone compared to the medullary bone of posterior teeth Due to sensory input, there is lower muscle activity when the canines are in contact Therefore, the canines are the best teeth to be in contact during a laterotrusive movement Arrangement is called canine guidance or canine rise occlusion Left laterotrusive movement illustrating canine guidance Okeson Fig. 5-14 * Optimal Force Magnitude Which of the anterior teeth are best suited to accept horizontal forces in eccentric movements? Canines Why? Longest and