ABSTRACT
The purpose of this study was to examine changes in functional parameters of patients with anterior crossbite in primary dentition during orthodontic treatment. Occlusal contact area (OCA), average bite pressure (ABP) and integrated occlusal load (IOL) were measured. Data obtained before the start of treatment (period A), data obtained when crossbite had improved (period B) and data obtained when the appliance had been removed (period C) were compared. OCA showed the lowest value in period B, and then gradually increased. ABP increased until period B and then declined or became constant. OCA and IOL showed significant differences in periods A and B and periods B and C (p < 0.05). The results suggest that about 6 months is required for stability of the occlusion and acquisition of function in the new occlusion after improvement of crossbite.
Subject(s)
Dental Occlusion , Malocclusion/physiopathology , Malocclusion/therapy , Bite Force , Case-Control Studies , Child , Child, Preschool , Dental Stress Analysis , Female , Humans , Jaw Relation Record/instrumentation , Male , Orthodontics, Corrective , Statistics, Nonparametric , Tooth, DeciduousABSTRACT
Physiological root resorption is a characteristic feature of human deciduous teeth. Pathological root resorption due to apical periodontitis, dental trauma or excessive orthodontic force is also observed in deciduous roots. The root resorption is not continuous, and has resting periods. In the resting period, cementum deposits in resorbed root surface. The deposited cementum in permanent teeth has been reported in detail. However, the deposited cementum in deciduous teeth is unclear. The present study examined apices of roots of human deciduous incisors with apical periodontitis and roots of sound deciduous incisors by light and transmission electron microscopy. Root dentin and original cementum had a severe irregular caved surface. Cementum was partially deposited on the caved root surfaces. The deposited cementum had made the caved root surface relatively flat. The cementum was lax and had some defects. The deposited cementum was belt-like in shape and had a stratified structure. Each layer had various structures consisting of abundant microfibrils and fine granular materials, microfibrils, granular materials, and collagen fibrils, a few fibrils and granular materials and a relatively homogeneous structure. The original cementum had many collagen fibrils, such as intrinsic and extrinsic fibers, and no granular materials or homogeneous structure. Therefore, structure of the deposited cementum was very different from that of original cementum in deciduous teeth and from that of deposited cementum in permanent teeth.
