[Study on the effect of ultrasonic irrigation in deactivating and eliminating the endotoxin in the root canals of chronic periapical periodontitis].

OBJECTIVE: To study the effect of ultrasonic irrigation in deactivating and eliminating the endotoxin in the root canals of chronic periapical periodontitis. METHODS: 10 maxillary premolars with 2 root canals extracted because of serious chronic periapical periodontitis were opened conventionally and prepared with modified double-flared technique with apical foramen sealed. 30 microL 3% H2O2 solution was introduced into each root canal and 2 minutes ultrasonic vibration was given. Samples were taken before and after ultrasonic vibration. 10 maxillary premolars with 2 root canals of chronic periapical periodontitis of 10 patients in clinic were selected. The root canals of them were instrumented as above, followed by 2 minutes ultrasonic irrigation with asepsis distilled water. Samples were taken before, after root canal preparation and after ultrasonic irrigation. The endotoxin activity of them was tested by kinetic turbidimetric limulus test. RESULTS: The mean endotoxin activity of extracted premolars before ultrasonic vibration was 4.069 EU x mL(-1) while after ultrasonic vibration it was 16.410 EU x mL(-1). There was great statistical difference between them (P < 0.01). The endotoxin activity after ultrasonic vibration was significantly higher than that of before vibration. The clinically mean endotoxin activity before, after root canal preparation and after ultrasonic irrigation were 44.860, 4.099, and 0.116 EU mL1 respectively. There was great statistical difference between the endotoxin activity before and after root canal preparation (P < 0.01). After the preparation, the endotoxin activity droped obviously. There was great statistical difference between the endotoxin activity before and after ultrasonic irrigation (P < 0.01). After ultrasonic irrigation, the endotoxin activity droped obviously. CONCLUSION: Under the condition of simulating clinical work presence, the ultrasonic irrigation can not intensify the effect of the root canal rinse solution in deactivating the endotoxin of infected root canals, but it may intensify the effect of the root canal rinse solution in eliminating the endotoxin of infected root canals.

[Effects on Helicobacter pylori reinfection in gastric mucosa by two oral plaque control methods].

OBJECTIVE: To investigate the reinfection rate of Helicobacter pylori (H. pylori) in gastric mucosa by two measures of oral plaque control on patients, and to demonstrate the necessity and better method of plaque control on those patients. METHODS: 148 patients suffered gastritis or gastroduodenal ulcer were assigned into test group 1 (54 patients), test group 2 (55 patients) and control group (39 patients). 13C-urea breath test proved that there were no H. pylori in their gastric mucosa. Daily plaque control was used in test group 1, oral professorial interventions were added into test group 2, neither daily plaque control nor oral professorial interventions was conducted in control group. All patients were conducted 13C-urea breath test again after half a year to determine the reinfection rate of H. pylori in gastric mucosa. RESULTS: 5 patients were eliminated because of stopping mouthwash in the test group 1, 8 patients failed to control dental plaque in the test group 2. The infection rates of H. pylori in gastric mucosa of test group 1, test group 2 and control group were 67.3%, 19.1%, 82.1%, respectively. The infection rate of H. pylori of test group 2 was lower significantly than that in control group and test group 1 (chi2=33, P<0.05; chi2=31.06, P<0.05). There were no significant difference between test group 1 and control group (chi2=2.43, 0.1

[Cost effectiveness analysis of two methods of preparing molar root canals].

PURPOSE: To evaluate the short-term clinical curative effects, cost effective ratio between ProFile nickel-titanium rotary preparation technique and stainless steel hand K-files preparation technique in molar root canal therapy. METHODS: All patients were randomly divided into two groups: 49 cases were prepared with stainless steel hand K-files in routine preparation technique; 45 cases were prepared with ProFile nickel-titanium rotary instruments in step-down technique. The clinical symptoms and cost were recorded. The data was analyzed by SPSS11.5 software package. RESULTS: The satisfactory rate of clinical effect of the NRPT group was significantly higher than SSPT(P = 0.034); The mean cost of the NRPT was significantly higher than SSPT (P = 0.001), the satisfactory rate of NRPT in severe curve subgroup was significantly higher than that of SSPT (P = 0.007), however, the C/E of NRPT was 394.52 Yuan less than SSPT. The former was 192.04 Yuan more than the latter in light curve subgroup. When it was classified by periapical condition before treatment, the satisfactory rate of NRPT was significantly higher than SSPT in negative subgroup yet (P = 0.012), the C/E of the former was 32.32 Yuan more than the latter; nevertheless, the C/E of the former was 376.47 Yuan more than the latter in positive subgroup; CONCLUSIONS: It is better to prepare with ProFile nickel-titanium rotary preparation technique in severe curve subgroup, however, the light curve subgroup should be prepared with stainless steel hand K-files preparation technique. To patients with positive periodontopathy, SSPT would save the cost of treatments, nevertheless, NRPT group have a higher short-term recent effect.

[The effect of coronal preflaring on the working length measurement of root canals in molars].

PURPOSE: To study the influence of coronal preflaring of root canal on the working length measurement in molars. METHODS: 48 molars from 47 adult patients with pulpitis were divided into two groups randomly. 74 root canals of 24 molars were examined in Group 1. After preparing an access cavity, the root canal orifices were located. A 15# K-type file was inserted into root canal to detect resistance at the apical region. 75 root canals of 24 molars were examined in Group 2. Before testing the apical resistance,a size 25# and 20# ProFile.06 taper NiTi rotary instrument was used to enlarge the canal orifice and flare the coronal portion of the root canal. After placing 15# K-type files, a radiograph was taken with the bisecting-angle technique. The distance between the tip of the file and the radiographic apex was measured on the radiographs. Statistical analysis of univariate and multiple logistic regression were carried out for analysis. RESULTS: There was a significant difference between the two groups (P<0.05), there were more accurate measurements in Group 2 than in Group 1. No statistical correlation was found between X-ray measurements and age, sex and the position of molars,while there was significant correlation between maxillary molars and mandibular molars (P<0.05). CONCLUSION: Preflaring the coronal portion of the root canals could significantly increase the accurate measurements of the working length of root canals in molars.