The effects of estrogen on experimental tooth movement in ovariectomized rats / 대한치과교정학회지

The purpose of this study was to evaluate the effect of estrogen on the periodontium and alveolar bone tissue response during experimental tooth movement in ovariectomized rats. Eighty female rats, 250gm in body weight, were classified into four groups ; sham operated group(NN), ovariectomized group(ON), ovariectomized & estrogen injected group(OE), sham operated & estrogen injected injected group(NE), Rats were ovariectomized before 3 weeks to begin the experiment, which resulted in estrogen-deficient osteoporosis. In OE group & NE group, estrogen was injected 50microgramg/kg B.W. every other days. The left maxillary 1st molar was moved mesially with 60g force. Each four rats were sacrificed after 1, 3, 7, 15 days from application of orthodontic appliance and after additional 7 days from removal of orthodontic appliance. Histological findings on mesial roots of upper 1st molar in pressure and tension side are observed. The results were summarized as follows ; 1. In pressure side of alveolar bone, the number of osteoclasts and Howship's lacuna of ON group was significantly more than that of NN group from 1 day to 15 days(P0.05). The amount of tooth movement of ON group between 7 days and 15 days was significantly greater than those of other groups(P0.05).

Anterior crossbite correction following craniofacial morphologic pattern in the early deciduous dentition / 대한치과교정학회지

Anterior crossbite is a common malocclusion in the early deciduous dentition. Even today, many these malocclusion patients are not treated until the mixed or permanent dentition. And the purpose here is to emphasize the need for early diagnosis and possible treatment for these anterior crossbite malocclusions and their associated facial patterns. Case histories of 4 patients selected from the author's practice are presented. Different methods of treatment are evaluated. Some improvement was achieved in all patients from an early interceptive regimen, although ultimately corrective orthodontic treatment may still be needed in some. It is concluded that early interception of deciduous anterior crossbite malocclusion should by attempted in patients; there should be no delemma in reaching such a decision. And it is essential for diagnosis and treatment to determine exact variations in growth when some appliance are used, it is recommended that growth-related records be made as early as possible.

A statistical study of clinical crown inclination in Korean's naturally occurring optimal occlusion / 대한치과교정학회지

The objective of this study was to evaluate some clinical aspect of the crown inclination in Korean's naturally occuring optimal occlusion, and to statistically compare the crown inclination at Andrews' FA points group and another bracket slot level group based on marginal ridges. The materials consisted of study models of 30 patients (14; Korean's males, 16; Korean's females) who have nonorthodontic normal occlusion. The results were as follows; 1. Mean, standard deviation, range of clinical inclination in the Andrews' FA points and another bracket slot level were obtained. 2. Statistically difference between Andrews' FA points group and bracket slot level group based on marginal ridge was non significant (p>0.05). But standard deviation and range in FA points group was more stability than marginal ridge group. 3. A lingual crown inclination at FA points in the upper posterior teeth existed (canines through molars). 4. The lingual crown inclination at FA points in the lower dentition progressively increased from the incisors through the second molars.

The prediction of postsurgical soft-tissue profile changes associated with surgical correction of the prognathic mandible by standardized facial photosurgery / 대한치과교정학회지

This study was designed to test the possibility of using a standardized lateral facial photographs as a clinical tool which produce the prediction of postsurgical soft-tissue profile changes associated with surgical correction in skeletal CIII patients. The number of the patients involved in this study were 27 in total, including 11 male patients and 16 female patients. A practical method to the utilization of presurgical photo prediction for mandibular prognathic patients has been presented. To predict postoperative facial appearance, montage photographs were superimposed on standard facial reference photos taken preoperatively. Within the limitations of its technology, postoperative predictions generated by this method were of sufficient accuracy, especially mandible and chin area, for clinical use. In addition, they provide valuable communication and diagnostic information which may be used in formulating treatment plan in cases requiring corrective orthognathic surgery. But, the lip changes were somewhat exaggerated by photo prediction. Consequently, the photo prediction seems suitable for planning profile changes in orthognathic surgery that include mobilization of one main mandibular fragment. Futher investigations are needed to determine whether changes of soft-tissues and hard-tissues are sufficiently reproducible so that more meaningful predictive values can he established.

A histologic study of pulpal reaction after experimental tooth movement in rats / 대한치과교정학회지

It was the aim of this investigation to evaluate some histologic aspect of rat pulp tissue after it had been compromised by an experimental orthodontic force. Experimental animals of thirty five Spraque-Dawley rats were employed. The first upper molars had been successively mesial moved (initial load 100 gr.) with a closed coil spring during 21 days. The experimental periods were set on immediate, 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks following retention time. On each experimental period, the rats were killed and prepared for the light microscopy. After prepared with H/E stain and Gomori's one-step trichrome stain, the specimens were analyzed with evaluation criteria which were adopted in this study. The result may be summarized as follows; 1. The main pulp changes due to experimental orthodontic force included vacuolization of odontoblastic layer, circulation disturbance, root resorption, reduced pulp collagenous fiber density and mean cell count of pulp fibroblast in the immediate group. 2. The pulp tissue changes were revealed reversible because the relieved pulp tissues from experimental orthodontic force were recovered rapidly in each evaluation criteria during retention periods. 3. Compared with normal control group, pulp collagenous fiber density were decreased in immediated group (p< 0.01), but increased in each retention groups. These seem to suggest that the pulp tissues were aged after experimental orthodontic force conditions. 4. Compared with normal control group, mean cell counts of pulp fibroblasts were decreased in immediate group (p< 0.05), but increased continuous in each retention groups. These seem to indicate that the pulp tissues were highly regenerative after experimental orthodontic force conditions. 5. Compared with normal control group, root resorptions occurred in all immediate specimens (p<0.01) and they were healed in each retention periods, but often observed in 4 weeks retention group. These seem to indicate that root resorptions were recovered slowly after experimental orthodontic force conditions.