Cessation Of Eruption Research Articles

Incidence of Pathologies Associated with Impacted Mandibular Premolars and Third Molars

Impaction is the cessation of eruption or failure of a tooth to erupt caused by a physical barrier in theeruption path, abnormal positioning of tooth and loss of space are other impediments.The rising incidenceof impacted teeth and their influence on the dental arches have long been of concern to the oral maxillofacialsurgeons.The aim of the study is to evaluate different types of Mandibular pathologies associated withimpacted third molars. This was a retrospective study conducted in the Department of Oral and MaxillofacialSurgery in Saveetha Dental College, Chennai . A total of 470 cases ranging in the age from 18 years to 45years with the diagnosis of Impacted mandibular third molars were considered for this study. Data wereanalysed using IBM SPSS statistics.This study showed vertical impaction and mesioangular impaction weremost frequently involved in the formation of cystic lesions among which vertical impaction occupied (1.7%)and mesioangular impaction (0.2%).Tumors with 0.6% are associated with vertical impaction of mandibularthird molar followed by mesioangular and distoangular impactions.Within the limitation of the study,weobserved that there exists a significant incidence of Pathologies associated with impacted mandibular thirdmolars .

Video Microscope Observations of Human Premolar Eruption

It is now possible to observe with an accuracy of 1-2 microns the pattern of eruptive movements of a human premolar as it moves from gingival emergence to the occlusal plane. This was accomplished by use of a video microscope to track the position of an optical ruling on the erupting tooth relative to a reference ruling mounted on adjacent teeth that were in occlusion. Net eruptive movements averaging 25-75 microns occurred from one day to the next until the tooth was almost in occlusion; then the eruptive rate slowed. Eruption occurred almost entirely at night. During the day, there was a marked slowing or cessation of eruption and often intrusion, which appeared to be related to masticatory activity.

The effect of preventing eruption on the proliferative basal tissues of the rat lower incisor

Eruption was prevented in the continuously growing lower right incisor of 9 male and 10 female Wistar rats by the surgical procedure of either complete or partial root transection, thereby allowing for a separation of the process of tooth eruption from that of basal cell proliferation. The experimental tooth was cut down to the gingival margin immediately following operation to eliminate masticatory stress. Animals were killed 120 days after operation, following which the jaws were dissected out, radiographed and then sectioned. Following cessation of eruption, the outline of the basal portion of the “root” showed one of the following arrangements: (1) in 10 jaws it was in the form of a smooth curve similar to that of controls, (2) in 3 jaws it was more sharply curved than the controls so that the pulp opening faced directly upwards, (3) in the remaining 6 jaws it was completely recurved so that the pulp opening was directed anteriorly. Histological examination revealed the presence of continued enamel and dentine formation in this basal region with the latter tissue completely obliterating the normal pulp cavity except for a small cone-shaped area at the base. These results clearly demonstrate that the proliferative basal region of the rat incisor is capable of generating a force when eruption is prevented, sufficient to cause a significant change in root morphology. In one complete root transection specimen, the proximal segment continued to erupt forwards and penetrated the side of the socket and then the cheek to reach the exterior.

Effect of Hypophysectomy on the Incisor of the Rat.

The gross and microscopic anatomy and the rate of eruption of the incisors were studied in 2 groups of rats: A. Completely hypophysectomized. 16 animals. Age at operation: 34 to 64 days. Age at death: 145 to 459 days. B. Littermate controls. Some were unoperated but most were unsuccessfully subjected to operation. Normal oestrous cycles and normal rate of growth. 9 animals. Significant alterations were observed only in group A. The incisors of these animals were about two-thirds the size of those of the other groups as judged by planimeter readings of radiographs. In a few of the rats that lived longest after the operation there were seen definite waves on the exposed labial contour of the upper incisors. The rate of eruption was retarded about 7 days after the operation. This retardation was progressive until there was cessation of eruption. The radiographs of the teeth showed no changes in the size or structure of the molars but indicated very clearly striking disturbances in the form and structure of the rapidly-growing incisors, especially the upper incisors. There were 2 areas to be distinguished in the radiographs and the histologic sections: an anterior zone which comprised about eight or nine tenths of the tooth, and a basal zone which contained the base of the pulp and was the seat of activity of Hertwig's sheath. The tooth substance was practically solid in the anterior zone. The labial contour in the anterior zone was not an arc of a circle but was interrupted by several waves. In the basal zone the labial contour was distorted and presented multiple narrow and deep foldings. The histologic studies served to confirm and amplify the gross findings. The enamel-epithelium was lacking in the anterior zone and markedly reduced in the basal zone.