[Study of methods of decalcification for making united slices of tooth and affiliated periodontic tissues].

OBJECTIVE: To study the methods of decalcification for making united slices of tooth and affiliated periodontic tissues. METHODS: Twenty-one samples containing dog molars and affiliated periodontic tissues were divided into seven mean groups. The pH value of solution, time of decalcification, weight and volume of samples, and content of decalcified calcium were detected. The slices were observed by HE, specific, and immunohistochemical stain. RESULTS: The velocity of decalcification increased with decrease of solution pH. The weight of samples lightened by 37.61%, the volume reduced by 25.97% on average, and calcium decalcified was 174.49 mg per gram humid samples. The EDTA decalcification was slowest, but it was best. Decalcification was fast in Plank-Rycho solution while the section was worst, and faster in the formyl solution containing aluminium chloride than in EDTA, and the section was better. CONCLUSIONS: The 50% formyl solution containing aluminium chloride is an ideal decalcifying solution.

[Effect of nano-hydroxyapatite to glass ionomer cement].

OBJECTIVE: To investigate the mechanical character, microleakage and mineralizing potential of nano-hydroxyapatite (nano-HAP)-added glass ionomer cement(GIC). METHODS: 8% nano-HAP were incorporated into GIC as composite, and pure GIC as control. Both types of material were used to make 20 cylinders respectively in order to detect three-point flexural strength and compressive strength. Class V cavities were prepared in 120 molars extracted for orthodontic treatment, then were filled by two kinds of material. The microleakage at the composite-dentine interface was observed with confocal laser scanning microscope (CLSM) after stained with 1% rhodamin-B-isothiocyanate for 24 hours. Class V cavities were prepared in the molars of 4 healthy dogs, filled with composite, and the same molars in the other side were filled with GIC as control. The teeth were extracted to observe the mineralizing property with polarimetric microscope in 8 weeks after filling. RESULTS: Three-point flexural strength and compressive of nano-HAP-added GIC were increased compared with pure GIC (P < 0.001, P < 0.05). The nanoleakages and microleakages appeared at the material-dentine interface in the two groups, but there were more microleakages in control group than in experiment group (P = 0.004). New crystals of hydroxyapatite were formed into a new mineralizing zone at the interface of tooth and nano-HAP-added GIC, while there was no hydroxyapatite crystals formed at the interface of tooth and pure GIC. CONCLUSION: 8% nano-HAP-added GIC can tightly fill tooth and have mineralizing potential, and can be used as liner or filling material for prevention.

[Effect of TRAIL gene in human squamous cell carcinoma cell line induced by adenovirus].

OBJECTIVE: To study the apoptotic effect on the squamous cell carcinoma cell line TCa83 induced by recombined adenovirus vector containing TRAIL gene and CMV promoter. METHODS: The TCa83 cell line was firstly infected with different titre of AdCMV-EGFP containing enhanced green fluorescence protein gene (EGFP) as control, and investigated the transducing rate through fluorescence to obtain the definite titre. Then TCa83 cell line was infected with AdCMV-TRAIL in proper titre, and TRAIL gene was detected by means of RT-PCR. After TCa83 cell line was infected with AdCMV-TRAIL and AdCMV-EGFP at day 1, 3, 5, 7, the activity of TCa83 cell line were evaluated by MIT and the apoptosis were detected by flow cytometer. RESULTS: Proper titre was of 1,000 particles/cell, and TCa83 cell line could be infected 100% in this titre. TRAIL gene was detected by RT-PCR after infected with AdCMV-TRAIL. The activity of TCa83 decreased in both groups, but the AdCMV-TRAIL group decreased more sharply than AdCMV-EGFP group (P < 0.001). Both AdCMV-TRAIL and AdCMV-EGFP could lead to apoptosis of TCa83 cells, but the AdCMV-TRAIL, function stronger than AdCMV-EGFP. Especially there was remarkable statistic difference between two groups (P < 0.0001). CONCLUSION: AdCMV-TRAIL could effectively decrease the activity of TCa83 cell line and induce apoptosis.