Developmental anomalies of permanent lateral incisors in young patients.

OBJECTIVE: To elucidate the prevalence of developmental anomalies of permanent lateral incisors among young patients in Japan. STUDY DEIGN: A total of 1375 patients were observed between 1990 and 2008 at the Department of Pediatric Dentistry in the Kyushu Dental College Hospital and four private pediatric dental clinics in Kitakyushu City. Panoramic and periapical radiographs were examined for all those patients aged 5 to 19 years. RESULTS: The prevalence of agenesis of the lateral incisors was 7.3% (100 patients), with more girls than boys being affected. The prevalence rates of absent upper and lower lateral incisors were 2.7 and 4.8% (34 and 63 patients), respectively. Nine (0.7%) of the total patients had microdontia. Eruption disturbance was present in five patients (0.4%). Two of five patients presented with a disturbed eruption owing to an odontoma or a supernumerary tooth. CONCLUSION: In our study, the prevalence of agenesis of the lateral incisors was higher in Japanese children than in other populations, and eruption disturbance occurred less frequently than agenesis and microdontia. Nevertheless, the early differential diagnosis of an eruption disturbance is important in order to begin appropriate treatment at the optimal time.

Series of trinuclear NiIILnIIINiII complexes derived from 2,6-Di(acetoacetyl)pyridine: synthesis, structure, and magnetism.

Eighteen trinuclear NiII2LnIII complexes of 2,6-di(acetoacetyl)pyridine (H2L) (Ln=La-Lu except for Pm) were prepared by a "one-pot reaction" of H2L, Ni(NO3)2.6H2O, and Ln(NO3)3.nH2O in methanol. X-ray crystallographic studies indicate that two L2- ligands sandwich two NiII ions with the terminal 1,3-diketonate sites and one LnIII ion with the central 2,6-diacylpyridine site, forming the trinuclear [Ni2Ln(L)2] core of a linear NiLnNi structure. The terminal Ni assumes a six-coordinate geometry together with methanol or water molecules, and the central Ln assumes a 10-coordinate geometry together with two or three nitrate ions. The [Ni2Ln(L)2] core is essentially coplanar for large Ln ions (La, Ce, Pr, Nd) but shows a distortion with respect to the two L2- ligands for smaller Ln ions. Magnetic studies for the Ni2Ln complexes of diamagnetic LaIII and LuIII indicate an antiferromagnetic interaction between the terminal NiII ions. A magnetic analysis of the Ni2Gd complex based on the isotropic Heisenberg model indicates a ferromagnetic interaction between the adjacent NiII and GdIII ions and an antiferromagnetic interaction between the terminal NiII ions. The magnetic properties of other Ni2Ln complexes were studied on the basis of a numerical approach with the Ni2La complex and analogous Zn2Ln complexes, and they indicated that the NiII-LnIII interaction is weakly antiferromagnetic for Ln=Ce, Pr, and Nd and ferromagnetic for Ln=Gd, Tb, Dy, Ho, and Er.

Long term radiographic study of bilateral second premolars with immature root treated by apexogenesis and apexification.

A ten-year-old girl broke the central cusps of the mandibular second premolars. The mandibular right second premolar was treated with apexification and the left with apexogenesis. These methods were chosen in view of the presented clinical symptoms, radiographic findings, and outcome of bacterial cultures of root canal samples. At postoperative 2 years 8 months, disappearance of the focus, closure of the root canal, and formation of the root apex were observed in both mandibular premolars. The mandibular left second premolar demonstrated a nearly normal root formation and root apex morphology. Immediately beneath the extracted pulp, regular, uniform, and thick hard tissue was formed. Meanwhile, in the mandibular right second premolar, root growth was suspended, making the root short, and the contour was constructed in such a way that it encircled the distal apical area from the mesial side forming the root apex.