Discomfort caused by the circumferential comfortable retainer (CCR) as a removable maxillary retainer / 대한치과교정학회지

OBJECTIVE: The aim of this study was to illustrate the circumferential comfortable retainer (CCR) as a removable maxillary retainer with good potential patient compliance and to evaluate the discomfort of the retainers including distorted speech, gagging sensation and appliance discomfort. METHODS: Sixty-six orthodontic patients (male, 23; female, 43; mean age, 23.42 +/- 10.19 years) who received orthodontic treatment with fixed orthodontic appliances were randomly assigned to two groups after debonding, a conventional wraparound retainer (CWR) group that fully covers the palate with an acrylic plate and a highly polished surface, and a circumferential comfortable retainer (CCR) group which has a horseshoe shaped base plate with three folds on the anterior region. A questionnaire that had a visual analog scale (VAS) which consists of a 100-mm horizontal line with 2 end-points labeled "no discomfort" on the left and "worst discomfort" on the right, with regard to distorted speech, gagging sensation and discomfort, was administered to patients after 4 weeks of retainer wear. The Mann-Whitney test was used to test the hypothesis that there was no difference between the two retainers. RESULTS: Comparing distorted speech and discomfort, the CCR group significantly had lower values than the CWR group (p < 0.05). Comparing gagging sensation, the CCR group had lower values than the CWR group but there were no statistically significant differences between groups (p = 0.146). CONCLUSIONS: In conclusion, the results suggest that the circumferential comfortable retainer (CCR) might facilitate patient compliance and thereby improve the maintenance of the fixed orthodontic treatment outcome.

Comparison of slim bristled and V-shaped orthodontic toothbrushes in patients with fixed orthodontic appliances / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate the efficacy of a slim bristled toothbrush compared with a V-shaped orthodontic toothbrush in patients with fixed orthodontic appliances. METHODS: Thirty four orthodontic patients receiving edgewise treatment were randomly assigned to two groups, a slim bristled toothbrush (Nano silver slim care) and a V-shaped toothbrush (Oral-B). Plaque index, gingival index and bleeding index were recorded at the beginning of the study (baseline), 2 weeks, 4 weeks and 6 weeks after new toothbrushes were supplied and the results were analyzed statistically. RESULTS: No statistically significant differences were found for plaque index, gingival index and bleeding index between toothbrush groups during the 6 weeks. Plaque and gingival indices were decreased at 2 weeks and 4 weeks but increased at 6 weeks in both toothbrush groups. Bleeding index in the V-shaped toothbrush group showed the lowest value at 2 weeks then increased at 4 weeks and 6 weeks but in the slim bristled toothbrush group decreased from 2 weeks through 6 weeks to under baseline levels. Patients in their twenties had significantly lower values than teenagers in the slim bristled toothbrush group (p < 0.013). CONCLUSIONS: The results would suggest that both of the toothbrushes are equally effective but the use of a slim bristled toothbrush may be of benefit in promoting gingival health for fixed orthodontic appliance patients in their twenties and over.

Non-surgical treatment and retention of open bite in adult patients with orthodontic mini-implants / 대한치과교정학회지

Successful treatment of the non-growing patient with an open bite of either dental skeletal pattern often presents a difficult challenge. The morphologic pattern in anterior open bite is characterized by longer vertical dimensions, an increase in development of the maxillary posterior dento-alveolar structure and a steep mandibular plane. In such cases, molar intrusion would be a good remedy for treatment. This article reports the successful treatment and retention of two anterior open-bite cases. We used orthodontic mini-implants for treatment and a circumferential retainer with posterior bite block or skeletal fixed retainer for retention. The diagnostic criteria and mechanics for appropriate treatment are discussed. Our results suggest that open bite can be reduced successfully with intrusion of molars using orthodontic mini-implants (OMI) without orthognathic surgery, and that circumferential retainer with posterior bite block and skeletal fixed retainer are effective for retention.

Validity of Superimposition Range at 3-Dimensional Facial Images

Effects of bisphosphonate on alveolar bone resorption during experimental tooth movement in rats: Biochemical & histological observations / 대한치과교정학회지

This study was performed to examine the effect of bisphosphonate, an inhibitor of bone resorption, on the formation of osteoclast and bone resorption during experimental tooth movement. Whether bisphosphonate has a cytotoxicity in high dose was also examined. Eighty-seven male Sprague-Dawley rats. Weighing 260-350g, were classified into normal (no appliance + 0.9% NaCl), control (appliance + 0.9% NaCl) and four bisphosphonate-treated( appliance + 0.8mg, 4mg, 20mg, or 100mg/kg) groups. The maxillary left first molar was moved mesially with the tippping movement using 50-70g of force. Bisphosphonate(etidronate disodium)was injected intraperitoneally with a dose of 0.8mg, 4 mg, 20mg, or 100mg/kg simultaneously with the application of the orthodontic force. They were killed at day 1.3 or 7after the application of the orthodontic force. The activities of serum acid phosphatase and lactate dehydrogenase (LDH) were assayed, and osteoclasts and the degree of bone resorption were examined histologically. The results obtained were as follows: 1. Acid phosphatase activities were significantly higher in the appliance groups, both control and bisphosphonate-treated( 4, 20 and 100mg/kg) groups, at days 1and 3 than these in normal. At day 1, bisphosphonate -treated(4, 20mg/kg) groups showed even higher acid phosphatase than control. However, at day 7, no significant difference was noted between the control and bisphosphonate-treated groups. 2. LDH activities in the 4, 20mg/kg bisphosphonate-treated groups were increased during the experimental periods examined, but there were no significant differences in the 0.8, 100mg/kg bisphosphonate-treated groups. 3. There was no bone resorption at day 1, but severe bone resorption was observed at days 3and 7 in the control. Bone resorption was reduced by bisphosphonate-treatment at day 3. Bone resorption observed at day 7 was similar between the control and bisphosphonate-treated groups. 4. Few osteoclasts were observed at the alveolar bone in the control and biosphosphnate-treated groups at day 1. At day 3. numerous osteoclasts were shown in the control, the degree of which was reduced in bisphosphonate-treated groups. These results suggest that the inhibition of the osteoclast formation was not the mechanism of bone resorption by the bisphosphonate-treatment during experimenal tooth movement. There was no distinct cytotoxicity with a high dose of bisphosphonate. And the drug should be administrated repeatedly to maintain the inhibitory effect of bone resorption.

A photoelastic study of the stress distribution in the alveolar bone by various molar uprighting springs / 대한치과교정학회지

This study was performed to analyze the effects of forces to the alveolar bone by various molar uprighting spring such as helical uprighting spring. T-loop spring, Modified T-loop spring and open coil spring. The simplified two-dimensional photoelastic model was constructed with a lower left posterior quadrant containing the second molar, the first and second premolars and the canine, with the first molar missing. Several molar up righting springs were fabricated from 0.017 by 0.022 inch blue Elgiloy and applied to the photoelastic model. Two-dimensional photoelastic stress analysis was performed, and the stress distribution was recorded by photography. The results obtained were as follows; 1. In all the kinds of the springs, the center of rotation of the mandibular second molar was observed at the apical 1/5-1/6 between the alveolar crest and the root apex. 2. In all the kinds of the spring, the stress induced in the mesial root surface of the mandibular second molar was relatively homogeneous but there was some difference in the magnitude of the stress. 3. In the kinds of the springs, the distal crown tipping moment of the second molar was increased in turn as open coil spring, helical uprighting spring, T-loop spring, and modified T-loop spring. 4. The largest extrusive force was occured in the T-loop spring, intrusive force was occured in Modified T-loop spring only, and the largest distal tipping force was occured in open coil spring. 5. In the T-loop spring with activation, the stress induced in the mesial root surface of the second molar was increased gradually from the root apex to the alveolar crest and highly concentrated in the alveolar crest.