The influence of an experimentally-induced malocclusion on vertebral alignment in rats: a controlled pilot study.

There is a growing interest in the relationship between occlusion and posture because of a greater incidence of neck and trunk pain in patients with occlusal dysfunction. The study was designed to verify whether an alteration of the spinal column alignment may be experimentally induced in rats as a consequence of altering dental occlusion and also to investigate whether the spinal column underwent any further changes when normal occlusion was then restored. Thirty rats were divided into two groups. Fifteen (15) rats (test group) wore an occlusal bite pad made of composite resin on the maxillary right first molar for a week (T1). The same rats wore a second composite bite pad for another week on the left first molar in order to rebalance dental occlusion (T2). Fifteen rats were included in an untreated control group. All the rats underwent total body radiographs at T0 (before the occlusal pad was placed), at T1 (one week after application of a resin occlusal bite pad on the maxillary left first molar) and at T2 (one week after application of a second resin occlusal bite pad on the maxillary right first molar). A scoliotic curve developed in all the test rats at T1. There were no alterations of spinal position observed in any of the control rats. Additionally, the spinal column returned to normal condition in 83% of the test rats when the balance in occlusal function was restored. The alignment of the spinal column seemed to be influenced by the dental occlusion.

Evaluation of cervical spine posture after functional therapy with FR-2: a longitudinal study.

The authors compared postural changes produced in 20 Caucasian female children treated with the Frankel Functional Regulator appliance (FR-2) (Frankel Industries, Morangis Cedex, France) using cephalometric tracings and comparing the tracings to 20 untreated Class II controls from the University of Chieti. Each patient in the study group was treated for exactly two years by the same operator using the FR-2 appliance and a standardized design and clinical technique, including prefunctional orthodontics where indicated. The average starting age was 8.4 yrs. (SD+/-2.1). At the end of the therapy, the average age was 10.3 yrs. (SD+/-2.4). Two teleradiographs were made of each patient: the first one at the beginning of treatment and the second one after six months. The radiographs were taken with the subjects standing in the ortho-position with no ear rods in the cephalostat; mirror position was carried out. In order to detect errors due to landmark identification, duplicate measurements were made using ten radiographs, and the error variance was calculated using Dahlberg's formula. Thirty-seven variables were studied. The cervical lordosis angle (CVT/EVT) was significantly higher in the study group as compared to the control group (p<0.05) at the end of treatment, probably due to a significant backward inclination of the upper segment of the cervical column (OPTNer and CVTNer) in the treated group (p<0.001 and p<0.01) from pre- to posttreatment. There was no significant change in the lower segment of the cervical column inclination (EVT/Ver). The changes resulted in a weak association in the multiple regression model to an increasing of maxillary base length and mandibular protrusion (R2=0.272; p<0.05). Other variables in the multiple regression were not significant.

Relationship between cervical lordosis and facial morphology in Caucasian women with a skeletal class II malocclusion: a cross-sectional study.

Several published studies show a relationship between craniofacial morphology and head posture. The aim of this study was to evaluate the association between cervical lordosis angle and mandibular length from lateral skull radiographs, and to investigate the relationship between mandibular retrusion and cervical lordosis angle decreasing. The sample comprised 70 Caucasian adult women, average 27.4, in skeletal class II and Angle class II. Lateral skull radiographs were obtained in natural head position (mirror position). Ten morphological variables were individuated on tracings. In order to assess errors due to landmark identification, double measurements were made in ten randomly selected radiographs and were compared with Dahlberg's formula. A Sperman's rank correlation test showed a negative correlation (P < 0.01) between cervical lordosis and mandibular length (compensatory curvature of the cervical spine) and positive correlation between anterior cranial base and maxillary length (P < 0.05). Based upon the cross-sectional method, no conclusion was possible about the mechanism concerning these results. Future longitudinal studies in growing patients should be directed to understanding the extent of environmental and genotype influences on cervical lordosis angle.