Tooth eruption involves a complex developmental process of tooth migration from the dental follicular origin to the final occlusion position in the oral cavity via the alveolar process. Disturbance of tooth eruption can occur at any point in a series of eruption stages; however, horizontal impaction of the mandibular first molar and primary retention of the primary mandibular second molar are rarely observed simultaneously. This study describes the treatment for two cases of horizontally impacted first molar with primary retention of primary molar. The primary retention of the primary mandibular second molar was extracted, and orthodontic traction was applied to the horizontally impacted primary mandibular first molar. Subsequently, displacement of the premolar tooth bud was improved and space regaining for eruption was achieved, guiding to normal eruption of the first molar.

The objective of this study is to analyze the shear bond strength of orthodontic buttons according to light tip distance and optic fiber diameter when an extended optic fiber was applied to the tip of a curing light unit.
In this study, 315 extracted premolar teeth were divided into 3 groups. Orthodontic buttons were attached using no optic fibers (Group I), 3.0 mm diameter optic fibers (Group II), or 5.0 mm diameter optic fibers (Group III). Each group was divided into subgroups A - C (5.0, 10.0, and 15.0 mm light tip distance), respectively. Shear bond strength was then measured while varying the light tip distance.
In group I, shear bond strength significantly decreased as the light tip distance increased. When the shear bond strength was evaluated according to the optic fiber diameter, no statistical significance was observed in group of 5.0 mm light tip distance. Compared with group IB, group IIIB showed significantly greater shear bond strength. Compared with group IC, all groups using 3.0 or 5.0 mm diameter optic fibers showed significantly greater shear bond strength.
Therefore, when a curing light unit has poor accessibility, optic fibers with a large diameter should be considered.

Bovine coronavirus (BCoV) causes severe diarrhea in newborn calves, and is associated with winter dysentery in adult cattle and respiratory infections in calves and feedlot cattle. Although the Korean BCoV vaccine strain, BC94, was isolated in 1995, there has still been no report of a molecular characterization of the vaccine strain. To characterize the vaccine strain, relationships between BC94 and field strains were investigated, based on sequence analysis and cross-immunity. We determined the complete sequences of the HE, N, and S genes from BC94 and four NVRQS isolates (SUN5, A3, 0501, 0502). Due to its major role in antigenicity, the spike proteins of the BCoVs were analyzed. BC94 showed distinctive genetic divergence from field isolates collected from 2002 to 2005. BC94, SUN5, and A3 had no virulence-specific sequence and there was a single amino acid change, from asparagine to lysine at residue 175, in the polymorphic region. Strains 0501 and 0502 had virulence-specific sequences at all seven sites. Although the recently isolated Korean BCoVs and BC94 were genetically different, the cleavage site of spike genes at 763~768 (KRRSRR) and the antigenic domain II of the spike protein, amino acid position 528, were conserved in all NVRQS isolates. The antigenic relatedness of KCD9, representative of recent Korean BCoVs, was compared with the Korean vaccine strain BC94. KCD9 showed cross-reactivity against BC94 by virus neutralization (VN) test. These results suggest that BC94 is antigenically closely related to field isolates and is still effective as a vaccine strain.
Adult ; Animals ; Asparagine ; Cattle ; Coronavirus, Bovine ; Diarrhea ; Dysentery ; Humans ; Infant, Newborn ; Korea ; Lysine ; Proteins ; Respiratory Tract Infections ; Sequence Analysis ; Sprains and Strains ; Viruses

Bovine coronavirus (BCoV) causes severe diarrhea in newborn calves, and is associated with winter dysentery in adult cattle and respiratory infections in calves and feedlot cattle. Although the Korean BCoV vaccine strain, BC94, was isolated in 1995, there has still been no report of a molecular characterization of the vaccine strain. To characterize the vaccine strain, relationships between BC94 and field strains were investigated, based on sequence analysis and cross-immunity. We determined the complete sequences of the HE, N, and S genes from BC94 and four NVRQS isolates (SUN5, A3, 0501, 0502). Due to its major role in antigenicity, the spike proteins of the BCoVs were analyzed. BC94 showed distinctive genetic divergence from field isolates collected from 2002 to 2005. BC94, SUN5, and A3 had no virulence-specific sequence and there was a single amino acid change, from asparagine to lysine at residue 175, in the polymorphic region. Strains 0501 and 0502 had virulence-specific sequences at all seven sites. Although the recently isolated Korean BCoVs and BC94 were genetically different, the cleavage site of spike genes at 763~768 (KRRSRR) and the antigenic domain II of the spike protein, amino acid position 528, were conserved in all NVRQS isolates. The antigenic relatedness of KCD9, representative of recent Korean BCoVs, was compared with the Korean vaccine strain BC94. KCD9 showed cross-reactivity against BC94 by virus neutralization (VN) test. These results suggest that BC94 is antigenically closely related to field isolates and is still effective as a vaccine strain.
Adult ; Animals ; Asparagine ; Cattle ; Coronavirus, Bovine ; Diarrhea ; Dysentery ; Humans ; Infant, Newborn ; Korea ; Lysine ; Proteins ; Respiratory Tract Infections ; Sequence Analysis ; Sprains and Strains ; Viruses