Apex radicis dentis excision operation guided by template made by CAD/CAM.

OBJECTIVE: The aim of the study is to explore the clinical efficacy of apex radicis dentis excision guided by a template made by Computer Aided Design/Computer Aided Manufacture (CAD/CAM). METHODS: Base on the CBCT image of oral cavity, a three-dimensional model of patient's oral cavity was built. Then the access way and excisional area were defined based on the model. Finally, the operative guide template was designed and made to help define the direction, depth, and area of the surgery. RESULTS: One year after the operation with guide template, the two cases of apex radicis dentis with difficulty in cure were proven to have normal masticatory function and their pathological changes of apex radicis dentis disappeared as well. CONCLUSION: Utilization of CAD/CAM technology could well design the operative guide template for the resection of apex radicis dentis. Usingthis guide template could make the excision of apex radicis dentis more quickly and safer.

Concentration of entangled nitrogen-vacancy centers in decoherence free subspace.

Exploiting the input-output process of low-Q cavities confining nitrogen-vacancy centers, we present an efficient entanglement concentration protocol on electron spin state in decoherence free subspace. Less entangled state can be concentrated to maximally entangled state with the assistance of single photon detection. With its robustness and scalability, the present protocol is immune to dephasing and can be further applied to quantum repeaters and distributed quantum computation.

Universal quantum controlled phase gate on photonic qubits based on nitrogen vacancy centers and microcavity resonators.

Here we investigate a physical implementation of the universal quantum controlled phase (CPHASE) gate operation on photonic qubits by using nitrogen vacancy (N-V) centers and microcavity resonators. The quantum CPHASE gate can be achieved by sending the photons through the microcavity and interacting with the N-V center. The proposed scheme can be further used for scalable quantum computation. We show that this technique provides us a deterministic source of cluster state generation on photonic qubits. In this scheme, only single photons and single N-V center are required and the proposed schemes are feasible with the current experimental technology.

[Retrospective cohort study on the rate of mother-to-child transmission among mothers infected with human immunodeficiency virus type 1 through blood transfusion].

OBJECTIVE: To study the rate of mother-to-child transmission (MTCT) on HIV-1. METHODS: All local residents from 8 townships in a region were screened for mothers who had a history of only one blood transfusion and 63 were found HIV-1 positive. A further study on these HIV-1 positive mothers and their children was conducted with the emphasis on the date of receiving blood transfusion, date and type of nationality, history regarding breastfeeding and so on. Sera specimens from 84 children born from 63 HIV-1 positive mothers were screened, using ELISA for HIV-1 antibody, and positive specimens were confirmed by Western-blot. RESULTS: The rate of MTCT was 32.1% (27/84) for children with all risk factors related to MTCT. Another 36.8% (7/19) were related to factors on intrauterine, intrapartum and breastfeeding, 35.7% (5/14) to intrapartum and breastfeeding factors, 14.3% (2/14) to intrauterine and intrapartum factors, 37.9% (11/29) to breastfeeding factor alone. By group combination analysis, the MTCT rate was 36.9% (24/65) with breastfeeding, 11.8% (2/17) with artificial feeding, and the former was significantly higher than the latter. CONCLUSION: HIV-1 MTCT rate among mothers caused by a single blood transfusion varied with different risk factors. Breastfeeding played an important role in MTCT, appeared in our study.

[Effect of self-etching primers on microleakage of resin composites in class V restorations]

OBJECTIVE: To evaluate in vitro microleakage of class V restorations using two self-etching primers with a flowable resin or hybrid resins. METHODS: Forty human molars were divided into 3 groups according to axial surfaces. Each group was randomly assigned to 2 subgroups (n=20) with either butt-joint or the beveled preparations. Class V preparations were cut in cemento-enamel junction. Groups A, B, C were respectively restored with CLB2/Clearfil AP-X, APMB/FHC-Merz or APMB/Liquicoat. Half specimens of each subgroup were thermocycled 2 500 times. After staining, dye penetration was evaluated in the ordinal scale at 40Xmagnifications for occlusal and the gingival margins. The wall adaptation of the randomly selected specimens was analyzed with a SEM on replicas of the sectioned teeth. RESULTS: None of bond systems in this study prevented the microleakge. The restorations with the bur-beveled preparations leaked the same as those with the butt joint preparations (P>0.05). The thermocycled specimens and the non-thermocycled specimens leaked similarly (P>0.05). The flowable resin-liqucoat leaked significantly more than hybrid resin in dentinal margins (P<0.05). CONCLUSION: The self-etching primers can not reduce the microleakge in the dentin-restoration interfaces. The flowable resin leak more than the hybrid resin in dentin-restoration interfaces. The bur- beveled preparations do not significantly reduce the microleakage in class V resin restorations bonded with self-etching primers.