Relationship between dental occlusion and posture

The purpose of this study is to show the effects of dental occlusion on postural position. Thirty subjects were divided into two groups: an experimental group who wore mandibular orthopedic repositioning appliances (MORA) and a control group who wore no oral device. All of the subjects underwent the same Fukuda-Unterberger experimental stepping test to check their postural attitude. Any deviation of the subject during the test from his initial position was analyzed. The results seemed to confirm that altering dental occlusion by wearing an oral appliance could induce some fluctuations in dynamic postural attitude. The phenomenon occurs after prolonged wearing of a MORA. Feedback effects are gradual after removing the mandibular splint.     

The influence of forward head posture on dental occlusion

A well established premise in the field of craniomandibular and cervical spine orthopedics is that forward head posture (FHP) adversely affects mandibular position and therefore dental occlusion. The purpose of this study was to investigate the influence of FHP on the initial occlusal contact pattern (IOCP) in order to provide further clarification on this important topic. Thirty-nine healthy subjects, 10-74 years old, underwent a series of tests in which the IOCP was recorded in four different head positions using the T-Scan Occlusal Diagnostic System. Three tests each were performed in military posture (MP), natural sitting posture (NP), FHP, and maximal forward head posture (MFHP) for a total of twelve trials. A repeated measures analysis of variance failed to demonstrate a correlation between FHP and IOCP; however, a multiple linear regression analysis revealed a relationship between age and the IOCP. This study raises questions about the relationship between FHP and occlusion.     

Effects of experimental occlusal interference on body posture: an optoelectronic stereophotogrammetric analysis

In recent years, there has been increasing interest in the relationship between dental occlusion and body posture both among people and in scientific literature. The aim of the present longitudinal study is to investigate the effects of an experimental occlusal interference on body posture by means of a force platform and an optoelectronic stereophotogrammetric analysis. An occlusal interference of a 0‐ to 2‐mm‐thick glass composite was prepared to disturb the intercuspal position while not creating interference during lateral or protrusive mandibular excursions. Frontal and sagittal kinematic parameters, dynamic gait measurements and superficial electromyographic (SEMG) activity of head and neck muscles were performed on 12 healthy subjects. Measurements were taken 10 days before the application of the occlusal interference, and then immediately before the application, the day after it, and at a distance of 7 and 14 days under four different exteroceptive conditions. The outcomes of this study show that an occlusal interference does not modify significantly over time static and dynamic parameters of body posture under different exteroceptive conditions. It has a minimal influence only on the frontal kinematic parameters related to mandibular position, and it induces a transient increase of the activity of masticatory muscles. In this study, the experimental occlusal interference did not significantly influence the body posture during a 14‐day follow‐up period.     

Dental occlusion and body posture: a surface EMG study

The influence between dental occlusion and body posture has been discussed in the past ten years by several authors with controversial conclusions. The objective of this study was to access, using surface electromyography (EMG), the rest activity of paired sternocleidomastoids, erectors spinae at L4 level, and soleus muscles in a group of 24 volunteer subjects (12 males, 12 females, aged 23-25 yrs) affected by sub-clinical dental malocclusions in different situations of dental occlusion. The subjects' occlusion was balanced (neuromuscularly) (registered on an acrylic wafer). Rest activity was assessed using the sEMG. The measurements were achieved on subjects while standing barefooted, before (Test 1), and 15 minutes after they wore the acrylic wafer (Test 2). The result was a significant reduction of the mean voltage for each muscle. Paired muscles were registered and the balancing rate between right and left muscles showed improvement for all the paired muscles (Wilcoxon test p < 0.05). No significant difference was noted in the relaxation and balancing rates between the muscles tested. The data confirmed a beneficial effect of balancing the occlusion with an acrylic wafer on the following paired postural muscles: sternocleidomostoid, erector spinae, and soleus.     

制取印模之体位与姿势探讨

人民卫生出版社2003年出版的第五版口腔修复学教科书与第四版相比增加了许多新的内容[1,2].在第五章印模与印模技术中,详细介绍了印模操作步骤和方法.其中在调节体位方面有如下描述:调整患者体位和头位,张口印模时最好保持上下颌牙弓( )平面与地面平行,患者头部高度与医生手操作高度相适应,保证医师用手固定托盘时也能保持舒适姿势……预备上颌印模时特别是用流动性较大的印模材,患者头部不应过分后仰,否则印模材向软腭流动,易引起恶心,造成患者紧张.为了描述清楚,作者还同时配合示意图加以说明(图1).     

The effect of body posture on the preferred vertical dimension of occlusion

Thirteen edentulous adults were investigated to see whether their preferred vertical dimension of occlusion (PVDO) was affected by vertical and horizontal body posture. The PVDO was found by the forced choice method using a graduated series of sticks in random sequence. The subjects were tested in both postures on two separate occasions. No significant difference was found between the PVDO's when the subjects were sitting upright and when they were supine. Nor was there any significant difference in the PVDO of the first and second sessions for either position.     

Effect of work on the body posture in dental team members

Differences between two working process technologies during the working time of a DMD and his/her team were studied. The study sample consisted of 16 dental medicine teams from the Zagreb area. One half of the teams were working using the conditionally termed old technology (T I), and the other half employed the new technology (T II). The aim of the study was to assess the extent to which the new technology elicited beneficial health-related effects on the team as a whole and on the working process in particular, as compared to the old technology. In particular sections of the process of work, differences were statistically significant, as shown by the results tabularly presented. Comparison of the two study groups was also carried out. It appears noteworthy to mention that the new technology, and even this one used for comparison in this study, should be expected to contribute to better working process which, in turn, might at the same time be one of the guidelines for future studies in dental medicine ergonomics.     

体位和操作方法对重度磨耗患者正中关系记录的影响

目的:记录6例口颌系统功能基本正常而需要建的中老年重度磨耗患者的正中关系,评价体位和操作方法对正中关系记录的影响。方法:铰链轴法确定髁突运动轴点,关系采用三维电子式髁突运动描记仪Pantronic记录并转移至Denar D5A型全调节式咬合架上,对6例需要建的重度磨耗患者正中关系,在不同体位下髁位的可重复性变化进行评价。结果:操作方法对正中关系的记录有一定影响。在前后方向,用双手扶持法BMP所获得的正中关系改变很小,且以仰卧位的变化最小;而颏点诱导法LCPG在2种体位下的位移量大,接近0.8mm。在上下方向,LCPG的位移量稍大于BMP,接近0.3mm。比较LCPG和BMP,在仰卧位,在前后方向上,LCPG和BMP之间存在0.65mm的均差,在上下方向存在0.17mm的均差,有明显的统计学差异(p<0.05)。在直立位,在前后方向,LCPG和BMP之间存在0.41mm的均差,但在上下方向的均差非常小(p>0.05)。结论:操作方法及体位对正中关系的记录有一定影响,临床若考虑采用BMP记录颌位,最好选用仰卧位进行记录,若考虑采用LCPG记录颌位,建议选用直立位进行记录,以提高记录结果的准确性。     

Biomechanical influences of head posture on occlusion: an experimental study using finite element analysis

The biomechanical influences of head posture on the cervical column and craniofacial complex during masticatory simulation were quantified using three-dimensional (3D) finite element analysis (FEA). Three types of finite element model (FEM) were designed to examine relationships between the position of the head and malocclusion. Model A was constructed to have a standardized cervical column curve, model B a forward inclined posture, and model C a backward inclined posture. The results of the spinal displacements revealed that model B moved in a forward direction and model C in a backward direction during masticatory simulation. The stress distributions on the cervical column (C1-C7) for models A, B, and C showed differences; stress converged at the atlas in model A, high-level stresses were observed at the spinous processes of C6 and C7 in model C, and the stress converged at the anterior edge in the vertebral body of C4 of model B. Stress distribution on the occlusal plane and maxillofacial structure did not show absolute differences among the three models. Alteration of head posture was directly related to stress distribution on the cervical column, but may not always directly influence the occlusal state.     

The influence of dental to facial midline discrepancies on dental attractiveness ratings

This study investigated the perception of discrepancies between the dental and facial midlines by orthodontists and young laypeople. A smiling photograph of a young adult female was modified by moving the dental midline relative to the facial midline. Twenty orthodontists (10 males and 10 females) and 20 young adult laypeople (10 males and 10 females) scored the attractiveness of the smile on the original image and each of the modified images using a 10-point scale. The results showed that the images were scored as less attractive both by the orthodontists and laypeople as the size of the dental to facial midline discrepancy increased. The scores were unrelated to the direction of the midline discrepancy (left or right) or to the gender of the judge. Further analysis revealed that the orthodontists were more sensitive than laypeople to small discrepancies between the dental and facial midline. It was estimated that the probability of a layperson recording a less favourable attractiveness score when there was a 2-mm discrepancy between the dental and facial midlines was 56 per cent.     

Dental occlusion and posture: an overview

Objectives

In recent decades, it has been suggested that disorders of the masticatory system such as malocclusions, can influence whole body posture. A growing number of patients are seeking concomitant treatment for dental malocclusions and postural disorders. The aim of this overview is to critically analyze the relationship between dental occlusion and posture.

Materials and methods

A literature overview was carried out to analyze the association between “malocclusion” versus “head posture”, “spine curvature”, and “body sway”.

Results

The studies showed that even if some associations have been found between occlusal factors and postural alterations, there is not enough scientific evidence to support a cause-effect relations. Most studies suffer from major flaws such as lack of control groups, failure to take into account for the possible confounders, inappropriate study design, and lack of sufficient reliability and validity of used diagnostic tests.

Conclusions

On the basis of this overview, it is not advisable to perform occlusal and/or orthodontic treatment, especially if irreversible and expensive, to treat or prevent postural imbalances or alteration of spine curvatures.     

Effects of mandibular position and body posture on nasal patency in normal awake subjects

The purpose of this study was to examine the changes in nasal patency induced by forward mandibular displacement or changes in body posture. Fifteen healthy adults participated in this study. To examine the influence of mandibular position, nasal resistance was recorded in intercuspal, middle, and maximum forward positions. To evaluate the effect of body posture, nasal resistance was recorded in the four postures of sitting erect, 30 degrees and 60 degrees dorsally reclined, and supine. The nasal patencies recorded in the middle and maximum forward mandibular positions were significantly higher than those recorded in the intercuspal position. Regarding the effect of body posture, the nasal patency showed a progressive decrease from the sitting erect position to the supine position. These results suggest that changes in mandibular position and body posture significantly affect nasal patency and that mandibular position and body posture should be considered basic information in the treatment of obstructive sleep apnea.     

State of the art: posture and occlusion

The Authors of this work propose to give an evaluation about actual relationship between posture and occlusion, trying of to give some indications about posture's meaning, organizing the relation about five points: Posture's definition Posture's history Posture's models of study Occlusal support en posture Diagnostic procedures.