Effects of Experimental Leg Length Discrepancies on Body Posture and Dental Occlusion

Abstract

The purpose of this study was to quantitatively evaluate the effects of experimental leg length discrepancies on body posture and dental occlusion. Thirty asymptomatic subjects (15 males and 15 females, ages 19-33, mean age 25.6 years) were included in this study and randomly assigned to one of two groups based on a table of random numbers. The only difference between group A and group B was the sequence of testing. Experimental leg length discrepancies were provided by using ten types of insoles with heights ranging from one to ten mm at one mm intervals, placed under both feet. The MatScan (Nitta Corp., Osaka, Japan) system was used to measure changes in body posture (center of foot pressure: COP) while subjects maintained the following three postural positions: 1. natural standing posture (control); 2. control with a heel lift under the right foot; or 3. control with a heel lift under the left foot. The T-Scan II system (Nitta Corp., Osaka, Japan) was used to analyze the results of changes in dental occlusion (center of occlusal force: COF) in the above-mentioned three postural positions. When subjects used a heel lift of six mm or more under the right foot, lateral weight distribution (LWD) shifted to the right side compared to the control (p<0.05). When a heel lift of four mm or more was used under the left foot, LWD shifted to the left side compared to the control (p<0.05). When subjects used a heel lift of eight mm or more under the right foot, occlusal force shifted to the right side compared to the control (p<0.05). When subjects used a heel lift of seven mm or more under the left foot, occlusal force shifted to the left side compared to the control (p<0.05). Based on these findings, it was concluded that leg length discrepancy affected body posture and dental occlusion.

Additional information

Notes on contributors

Nozomi Maeda

Dr. Nozomi Maeda is a graduate student at the Department of Oral Functional Prosthodontics at Hokkaido University Graduate School of Dental Medicine, Japan. She received her D.D.S. degree at Hokkaido University in 2005.

Kiwamu Sakaguchi

Dr. Kiwamu Sakaguchi is an assistant professor at the Department of Oral Functional Prosthodontics at Hokkaido University Graduate School of Dental Medicine, Japan. He received his D.D.S. degree at Hokkaido University in 1995 and his Ph.D. degree from the same university in 1999. During 2003-2004, he joined the Craniofacial Pain Center at Tufts University where he engaged in reseach.

Noshir R. Mehta

Dr. Noshir R. Mehta is a professor and chairman of general dentistry, director of the Craniofacial Pain Center and Assistant Dean of International Relations at Tufts University School of Dental Medicine. He is a diplomate of the American Board of Orofacial Pain and is a fellow of the International College of Dentists and of the American College of Dentists. Since receiving his D.M.D. degree and his M.S. in periodontics at Tufts University, he has been involved in occlusion research. Dr. Mehta has lectured internationally on TMD/MPD and has published numerous scientific articles.

Emad F. Abdallah

Dr. Emad F. Abdallah is an assistant professor at the Craniofacial Pain Center, Tufts University School of Dental Medicine. He received his D.M.D. degree, certificate in orthodontics, Masters of Science degree and certificate in temporomandibular disorders and orofacial pain from Tufts University. He is a diplomate of the American Board of Orofacial Pain. Dr. Abdallah has lectured internationally on orthodontics and orofacial pain.

Albert G. Forgione

Dr. Albert G. Forgione is Chief Clinical Consultant at the Craniofacial Pain Center, Tufts University School of Dental Medicine. He received a Ph.D. in psychology from Boston University and then joined Tufts University and lectured in behavioral medicine. Dr. Forgione established the first TMJ center at Tufts University School of Dental Medicine with Dr. Mehta in 1978.

Atsuro Yokoyama

Dr. Atsuro Yokoyama is a professor at the Department of Oral Functional Prosthodontics at Hokkaido University Graduate School of Dental Medicine, Japan. He received his D.D.S. degree at Hokkaido University in 1984 and his Ph.D. degree from the same university in 1988.