Symmetry of root anatomy and root canal morphology in maxillary premolars analyzed using cone-beam computed tomography.

Objective: This study aimed to use cone-beam computed tomography (CBCT) to evaluate the root anatomy and canal morphology of maxillary premolars in a Chinese population and determine their degree of bilateral symmetry.

Design: 774 CBCT images were retrospectively analyzed, representing 1387 maxillary first premolars and 1403 second premolars. The number of roots and canals were recorded.

[The effect of bacteria reaction time on corrosion properties of Ni-Cr alloys pretreated with different proteins].

Purpose: To evaluate the corrosion properties of absorbed protein on the surface of NiCr alloys, and provide experimental base for corrosion resistance of dental casting alloys.

Methods: NiCr alloy specimens were divided into 3 groups: one group was exposed to the artificial saliva(control group), and the other 2 groups were exposed to the artificial saliva with 1% bovine serum albumin(BSA), or 0.22% lysozyme(LSZ).

[The effect of additional polyphosphazene nanotubes in polyurethane composites on microorganisms adhesion].

Puppose: To investigate Candida albicans and Streptococcus mutans adhesion to 3 polyurethane composites [pure polyurethane (PU), 1% polyphosphazene-containing polyurethane (PZS-1%) and 5% polyphosphazene-containing polyurethane (PZS-5%)].

Methods: Two kinds of microorganism suspension were incubated with the specimens under certain culture conditions and the roughness of 3 materials were determined before adhesion tests. Microorganism attached to the specimen were then observed under optical microscope, and viable micro-organisms adhered to the specimen were then counted and removed.

[Study of the relationship between patients' personality traits and satisfaction after fixed denture restorations].

Purpose: To investigate 98 fixed denture patients' personality traits and the relationship between patients' personality traits and satisfaction with fixed denture restoration.

Methods: 16PF questionnaire and satisfaction questionnaire were used to study 98 fixed denture patients' personality traits and the relationship between personality traits and general satisfaction and specific satisfaction. The data was analyzed with SPSS17.

[Analysis of the bacterium adhesions on the surface of PFM materials in vitro].

Purpose: With the observation of bacterial adhesion on the surface of the PFM and enamel, we analyzed the sequence of these adhesions and offer options for prevention of their occurrence.

Methods: The specimen made of PFM were polished step by step. Then they, along with the enamel were put into the liquid BHI culture medium containing Ua, Pg and An.

[Analysis of the surface roughness and bacterium adhesions on the surface of restorative materials in vitro].

Purpose: To observe the common oral bacteria adhesion on the surface of prosthesis with different roughness, and to analyze the sequence of these adhesions and offer the options for better prosthesis and prevention of their occurrence.

Methods: The specimens made of Co-Cr alloy were polished step by step and divided into six groups. Then, they were put into the liquid BHI culture medium containing Ua, An and Pg.

[Study of dental alloys in the artificial saliva using an electrochemical impedance spectroscopy].

Purpose: With the help of electrochemical impedance spectroscopy (EIS), the purpose of the study was to investigate the corrosion resistance of CoCr alloys ,NiCr alloys and commercially pure Ti(cp Ti) in the artificial saliva(AS).

Methods: With the EIS, a test was made on the three alloys/metals in the AS (See Bode plot and Nyquist plot). And then, an analysis was made on what was known in the test by the software of ZSimpWin, after which the corrosion resistance of the alloys/metals was evaluated against the parameters of equivalent circuit [R(CR)].

[A preliminary analysis of the ratio between the upper and lower anterior teeth].

Purpose: The widths of anterior teeth are measured and compared to see if there was any specific ratio between the anterior teeth, and to provide some referential data for clinical application in esthetic dentistry.

Methods: Gypsum casts of the maxillary and mandibular arches were made by traditional ways. With the help of dividers and vernier calipers, the widths of anterior teeth were measured.

[Adhesion of different bacterium to the surface of restorative materials in vitro].

Purpose: Mutans(Ua), porphynomonas(Pg),actinomyces Naeslundii(An) are the 3 bacteria that may cause the clonal formation, gingivitis and periodontitis. The aim of this study was to observe adhesion on the surface of the dental restorative materials and enamel, and to analyze the sequence of these adhesions and offer now the options for the prevention of their occurrence.

Methods: The specimen made of PFM and Co-Cr alloy were polished step by step.

[Effect of five kinds of pigments on the chromaticity of dental zirconia ceramic].

Purpose: All-ceramic dental restorations should match the colour of the natural teeth in order to fulfill aesthetic demands. The goal of this study was to evaluate the colouration of zirconia ceramic by adding five kinds of pigments. The influence of the pigments concentrations on the chromaticity were also analysed.

[Characters of the surface of the cast-bonded keeper: an experimental study].

Purpose: This study is aimed to analyze the characters of the surface of the keeper after cast-bonded in varied temperatures.

Methods: Twelve keepers were divided into three groups: the gold alloy group, the Ni-Cr alloy group and the Ti group with four samples in each group. A sample that contained a Magdisc 500 keeper was fabricated with the cast-bonded technique.

[A comparison between the cast-bonded keeper with different dental alloys in the metallographic structure].

Purpose: The aim of this study is to investigate the changes of the metallographic structure of the cast-bonded keeper when cast in varied temperatures.

Methods: Three groups were included in this study: the gold alloy group, the Ni-Cr alloy group and Ti group, with the Magdisc 500 keeper as the control group. Each sample that contained a Magdisc 500 keeper was fabricated with the cast-bonded technique.

[The role of the mouthguard in preventing sports-related oral-facial and dental traumas.].

Sports play a significant role in all nations worldwide. More and more people involve in sports so that the incidence of the oral-facial and dental traumas with accidents ascends. The treatment cost is considerable, and the sporters' lives will be influenced by these traumas.

[The influence of cerebral blood flow of volunteers with magnetic attachment measured by transcranial Doppler].

Purpose: To investigate the influence of cerebral blood flow of volunteers with magnetic attachment.

Method: The mean flow velocity of the middle cerebral arteries (MCA) of 24 volunteers with magnetic attachment denture were measured by transcranial Doppler (TCD). All data were analyzed by SPSS10.

[The establishment of 3D-FE model libraries for the elements of FPD].

Purpose: To establish the 3D-FE model libraries for the elements of the FPD.

Methods: Based on the 3-D geometric model libraries of the normal stomatognathic system, using the software, such as Powershape,Pro/E and Ansys5.5, the models of abutments,retainers and pontics were created according to the models of natural crowns.