[All-ceramic resin bonded fixed partial denture made of IPS hot-pressed casting porcelain restore anterior missing teeth: a three years clinical observation].

OBJECTIVE: To clinic observation of IPS Empress2 and IPS e.max all ceramic resin bonded fixed partial dentures used in one anterior teeth lost in upper jaw or less than two anterior tooth lost in lower jaw. METHODS: 22 patients, 26 restorations had been made, which included 16 single-retainer all ceramic resin bonded fixed partial dentures and 10 two-retainers all ceramic resin bonded fixed partial dentures. Secondary caries of the abutments, shade in the margin of the retainers and the integrity of the restorations had been observed at 3 months, 6 months, 1 year, 2 years and 3 years after all ceramic resin bonded fixed partial dentures having been bonded. RESULTS: In the 3 years of clinic observation of the anterior all ceramic resin bonded fixed partial dentures, 1 two-retainers restoration lost bond after it had been made for 3 months, a retainer of one two-retainers restoration was broken after 6 months, but they are still used after modified as one-retainer all ceramic resin bonded fixed partial dentures, 1 two-retainers restoration lost bond two year later, It was integrity and re-bonded again that was still stable. No secondary carries and no shade in margin of the retainers had been found. Their color matches with the nature teeth excellently. The success rate was 88.5%. CONCLUSION: IPS Empress 2 and IPS e.max all ceramic resin bonded fixed partial dentures should be a good selection in one or two teeth lose in anterior jaws.

[Experimental mechanics analysis of posterior galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps].

OBJECTIVE: To measure the fracture strength of the posterior galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps with highly temperature-resistant adhesive and to provide reference data for clinical application. METHODS: A standard low dental cast was achieved with 46 missing. Five posterior galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps, with abutments being 47 and 45. The low dental cast was fixed on the panel of the universal testing machine, vertical load given on the central of the pontic as the velocity of 2 mm/min. RESULTS: The fracture strength of the posterior galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps was (877.00+/-126.53) N, the fracture strength of the metal frame was (1,448.94+/-51.02) N. CONCLUSION: Posterior galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps could endure the normal human occlusal force.

[A three-year clinical evaluation of galvano-ceramic bridges made by Ni-Cr pontic bonding galvano caps].

OBJECTIVE: To evaluate the clinical effect of galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps with highly temperature-resistant adhesive based on three-year clinical trials. METHODS: A total of 29 galvano-ceramic bridges made by Ni-Cr pontic fired bonding on the galvano caps were used for 26 patients. Abutment teeth plaque indices (PI) were compared according to Silness and Löe standards and their papillary bleeding indices (PBI) according to Mazza standards before restoration and after 36 months' restoration. At the same time, the integrity and marginal fitness of galvano-ceramic bridges were observed. RESULTS: The PBI at abutment teeth were higher than those before restoration, Wilcoxon test revealed significant difference. Their PI were lower than those before restoration, Wilcoxon test revealed significant difference. All the galvano-ceramic bridges were perfect in marginal fitness and color. The rate of integrity was 89.7% in the period of observation. CONCLUSION: Galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps with highly temperature-resistant adhesive hold out good prospects for clinical use in fixed restoration.

[Toxicity of niclosamide with plastic film mulching to fish].

OBJECTIVE: To observe the toxicity of niclosamide with plastic film mulching to fish. METHODS: A ditch with Oncomelania snails was selected as the study site, and it was divided into a control group and a molluscicide group. After the river closure, the molluscicidal group was sprayed with niclosamide with a dosage of 2 g/m2, and then covered with plastic film; no molluscicide measure was implemented in the control group. The toxicity of the molluscicide to carp fish in resting and flowing water environment was observed. RESULTS: In flowing water, the death rates of carp fry of the molluscicidal and control groups showed no statistical difference 7 d after the film mulching (P = 0. 680), and no carp fry died in the 2 groups after plastic film taking off for 4 d. The death rates of carp fry between the 3 sites (with a distance of 50, 100 and 150 m from the molluscicidal group, respectively) and the control group had no statistical difference 7 d after film mulching (P = 0.955), and no dead fry was discovered 4 d after taking off the film. In downstream, for the death rates of carp fry, there was no difference between the molluscicidal group and the control group (P = 0.376). The death rates of snails before and after the molluscicidal experiment showed a significant difference (P < 0.01). CONCLUSIONS: The technology of niclosamide molluscicide with plastic film mulching can not only improve the molluscicidal effect, but also avoid the toxicity to fish, which is suitable for special environment such as a fish pond.

[Two years clinical observation of anterior all zirconia ceramic resin bonded fixed partial dentures].

OBJECTIVE: To observe the restoration effect of anterior all zirconia ceramic resin bonded fixed partial dentures, and to find a new fixed restorative method for restoring one or two missing anterior teeth. METHODS: Twenty-nine missing anterior teeth from twenty-three patients were restored with all zirconia ceramic resin bonded fixed partial dentures, and restorations were devided in to two groups according to the number of retainers, i.e. the single-retainer group and the two-retainer group. The integrity, secondary caries, marginal shade and color match of the restorations were evaluated with the standard of American Public Health Association (APHA). The average period of observation was 22 months. RESULTS: One restoration from the two-retainer group failed, two restorations from the single-retainer group failed. The shade of two restorations were evaluated as discernable whiter compared to adjacent teeth. There was no secondary caries and marginal shade. The two year success rate of anterior all zirconia ceramic resin bonded fixed partial dentures was 90% (26/29). CONCLUSIONS: All zirconia ceramic resin bonded fixed partial dentures used for less than two anterior missing teeth can achieved definite aesthetic effect and physiologic function. It was a new type of fixed restoration for anterior missing teeth. However, to determine long-term result of this restoration more data are needed.

[Ultrastructural study of sclerotic dentin surface following the application of the Er, Cr: YSGG laser].

OBJECTIVE: To investigate the ultrastructure character of sclerotic dentin surface conditioned by the Er, Cr: YSGG laser and acid etching. METHODS: Sixteen human teeth with sclerotic dentin were randomly assigned to 4 groups, and conditioned with acid etching (Group A), laser irradiation (Group B), laser irradiation after acid etching (Group C), or acid etching after laser irradiation (Group D) respectively. The characters of surface ultrastructure were observed using scanning electron microscope (SEM). RESULTS: In Group A, the majority of dentin tubules were blocked by sclerotic rods. In Group B, the honeycomb-like change was found on the sclerotic dentin surface. The surface structure of Group C was similar to that of Group B. In group D etching wiped off the honeycomb-like structure. CONCLUSIONS: The sclerotic dentin surface treated with laser irradiation turns into uniform honeycomb-like structure. The rough surface may be beneficial to bonding strength on sclerotic dentin after laser irradiation.

[Three-dimensional finite element analysis of two different framework designs of compound galvano-ceramic bridges].

OBJECTIVE: To analyze stress distribution of two framework designs in compound galvano-ceramic bridges made with three-dimensional finite element models. METHODS: Three-dimensional finite element models were developed for compound galvano-ceramic bridges with two designed retainers of Ni-Cr frameworks which ringed or partially covered the electroformed gold caps. The models were vertically loaded 200 N on the center of the occlusal surface of the pontic and loaded 400 N on the center of buccoclusal marginal ridge from buccal aspect to lingual aspect at a 30 degree angle with the occlusion plane respectively. The stress distributions and the level of stress concentration in the two models were analyzed by the FEA software. RESULTS: Stress distributing in two designed framework of compound galvano-ceramic bridges were similar. The highest von Mises stress of compound galvano-ceramic bridges was concentrated in the distal connector of the pontic and retainer. Under the vertical loading, the von Mises stress was 24.17 MPa for the partial cover retainer of the Ni-Cr framework and 24.85 MPa for the circular retainer. Under the lateral loading, the corresponding figures were 42.83 MPa and 42.69 MPa. No matter vertical or lateral loading, the margin of electroformed cap was the concentration area of the von Miese stress. CONCLUSIONS: In this study, the stress concentration area of compound galvano-ceramic bridges with Ni-Cr framework and electroformed gold caps was the connector and the margin of electroformed cap was the insubstantial area.

[Changes of upper airway of obstructive sleep apnea syndrome patients after the treatment of Silensor snoreguard].

OBJECTIVE: To investigate the changes of upper airway of obstructive sleep apnea syndrome (OSAS) patients after the treatment of Silensor snoreguard. METHODS: 42 patients with OSAS were treated with dental appliance. Cephalometric analysis was carried out to compare the changes of upper airway before and after the treatment. RESULTS: SPP-SPPW increased from (9.10 +/- 2.25) mm to (12.24 +/- 2.61) mm. PAS increased from (8.99 +/- 3.20) mm to (11.24 +/- 3.79) mm. CL decreased from (26.26 +/- 6.04) mm to (14.37 +/- 8.14) mm. H-MP decreased from (21.27 +/- 6.12) mm to (12.14 +/- 5.89) mm. V -RGn decreased from (55.15 +/- 5.61) mm to (51.63 +/- 5.87) mm. OPAA increased from (7.01 +/- 1.54) mm2 to (7.85 +/- 1.61) mm2. HPAA increased from (3.02 +/- 0.89) mm2 to (3.61 +/- 1.61)mm2. CONCLUSION: Dental appliance worked with the effect of enlarging upper airway.

[The use of CAD/CAM system with zirconia in modern prosthodontics].

Computer assisted design/computer assisted machining (CAD/CAM) technology has received considerable clinical and research interest from modern dental practices as a means of delivering all-ceramic restorations. Up to now the CAD/CAM system with zirconia has the highest fracture strength in all all-ceramic materials, and consistently enabled the most esthetic, lifelike reproduction of natural dentition. They have been widely received by both dentists and patients. The CAD/CAM system with zirconia is indicated for crowns and bridges in natural teeth or implants and telescope dentures, the CAD/CAM with zirconia can be placed anywhere in the mouth, and can replace the porcelain crowns and bridges for single crown and bridges less than 6 units. This paper described the techniques of CAD/CAM system with zirconia in fabrication of crowns, bridges, telescope dentures and implant dentures with colored illustrations.