[Evaluation of effects of fluoride varnish on prevention of first permanent molar caries].

PURPOSE: To compare fluoride varnish and fluoride foam's effectiveness of preventing first permanent molar caries, and discuss patients' acceptance of the 2 materials among pupil patients. METHODS: Six hundred pupils aged 6-8 years from 3 primary schools in Shanghai Yangpu District were randomly selected.The subjects were randomly divided into 3 groups, with 200 students having 800 teeth in each. Two of these groups were experimental groups that receive fluoride varnish (Group A) and fluoride foam (Group B) respectively, and the third group (group C) was control group.Pupils in group A and group B received 2.26% Toro fluoride fluoride varnish, 1.23% fluoride foam was applied to the first molars. In the next 2 years, all pupils received dental health education every half year. The pupils' conditions of first permanent molar caries were checked in the sixth, twelfth, eighteenth and twenty-fourth month since the study started. Statistical analysis was performed using SPSS 10.0 software package. RESULTS: After 6 months, there was no significant difference between the 3 groups (P>0.05), the rate of caries incidence in the experimental group B was significantly higher than group A during the observation period after 12 months (P<0.05). Caries incidence in both group A and B was lower than the control group, with significant difference (P<0.05). CONCLUSIONS: Both duraphat fluoride varnish and fluoride foam prove to be effective in caries prevention. Moreover, considering other factors such as safety, convenience and cost, fluoride protector will be an even better choice in practical use.

[Study of the root canal characteristics of mandibular central incisors in 150 patients using cone-beam computed tomography].

PURPOSE: To investigate the root canal characteristics of mandibular central incisors using a cone-beam computed tomography (CBCT) technique. METHODS: One hundred and fifty patients (79 males and 71 females) receiving CBCT scan at Shanghai Ninth People's Hospital were recruited into this study. A total of 295 image samples of mandibular central incisors were obtained and analyzed in terms of the number and type of root canals. RESULTS: The majority of mandibular central incisors had a single canal (61% possessed a Type I canal system). Although 39% of the roots possessed two canals, only 8.8%had two separate apical foramina. CONCLUSIONS: The prevalence of two canals of mandibular central incisors in this case series was 39% and is within the range reported by previous studies on case series of different racial origin.

[Clinical study on prevention root absorption after teeth replantation with Vitapex paste].

PURPOSE: To evaluate the result of using Vitapex paste for preventing root absorption after replanting the avulsed teeth. METHODS: Thirty patients with 36 avulsed upper anterior teeth with fully developed apices within 5 hours of trauma were enrolled in this study. For each case, the tooth and its alveolar site were irrigated with 0.9%NaCl, then the tooth was put into its original site and fixed with steel wires and composite resin. Two weeks later,the involved teeth underwent pulpectomy and were randomly divided into two groups. Ca(OH)2 paste was used for temporary root canal filling in group A, and Vitapex paste in group B. The patients were asked to recall every three months, X-ray film was taken to evaluate root absorption and the same temporary root canal filling material was replaced. The permanent root canal filling was performed about one and a half years after treatment when root absorption stopped. Statistical analysis was carried out using SPSS12.0 software package. RESULT: The success rate of two groups was not significantly different, though which was a little higher one year after treatment in group A than group B (88.9% vs. 83.3%). Vitapex paste had the benefits of both Ca(OH)2 and iodoform. The radiopaque of iodoform made Vitapex paste observed easily for the status of filling or absorption. CONCLUSIONS: The injection style of Vitapex paste makes it easily being manipulated. Vitapex paste is an ideal material for preventing root absorption of replanted avulsed teeth. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No. 08DZ2271100).

[Evaluation of X-ray beam angulation for successful four canals identification in the mandibular first molars].

PURPOSE: This study was aimed to determine the most effective horizontal beam angulation to identify 4 canals in the mandibular first molars, so as to provide full and accurate information for the clinic. METHODS: One hundred and twenty mandibular first molars with four canals that needed endodontic treatment in vivo were selected. Radiographs were taken at horizontal angles of 0,10,20 degrees from distal direction and 0,10,20,30 degrees from mesial direction of the tooth. The numbers of root canal and the degree of resolution were identified and recorded by 3 independent observers. Data were analyzed using SPSS10.0 software package or Chi-square test. RESULTS: At 30 and 20 degrees from mesial direction, 93.3% and 90.0% of all the 120 teeth were correctly identified as 4 canals, compared with 0 degree of 40.0%(P<0.01). Of them, 71.5% and 89.7% could be classified as with high resolution, respectively. The latter was not significantly lower than 0 degree of 95.0% (P>0.05). CONCLUSION: Twenty degrees from mesial direction is the most effective X-ray beam angle in diagnosing 4 canals of the first mandibular molars. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100).

Prevalence of 3-rooted first permanent molars among a Shanghai Chinese population.

OBJECTIVES: This study aimed to assess the prevalence of 3-rooted mandibular first molars among a Shanghai Chinese population by using periapical radiographs. METHODS: A total of 510 patients possessing both mandibular first molars were selected. The radiographs of these cases were evaluated under optimal conditions using double magnifying glasses. The incidence of 3-rooted mandibular first molars and the correlation between occurrences in males and females and between the left and right sides were recorded and analyzed. A total of 1020 mandibular first molars were evaluated. RESULTS: A total of 165 patients were found to have a 3-rooted mandibular first molar: 92 males and 73 females (P = .106). The overall incidence of patients with 3-rooted mandibular first molars was 32.35%. Of all the patients with 3-rooted molars, 67.27% (111/165) of cases occurred bilaterally. The incidence of teeth showing an extra root was 27.06%. The occurrence of such permanent 3-rooted mandibular first molars also did not differ significantly between the right side (n = 142, 13.92%) and the left side (n = 134, 13.14%; P = .573). CONCLUSIONS: The prevalence and bilateral incidence of 3-rooted mandibular first molars among the Shanghai Chinese population was high and such variation varied among Chinese populations living in different areas.

[The use of 1% dyclonine and local cryoanesthesia plus pulp vitality test agent in taking dental X-ray film].

PURPOSE: To analyze the effect of topical anesthetics in taking dental X-ray film. METHODS: 300 patients, who needed to take dental X-ray photography of maxillary or mandibular molar were randomly assigned to 3 groups. Bisecting angle technique was used to take the film. Before taking the X-ray, the throats of the patients in Group I were treated by 1% dyclonine spraying anesthesia, Group II were treated by FRILJET local cryoanesthesia and pulp vitality test agent, and Group III were set as control. The anesthesia efficiency and imagine quality of the dental films were evaluated, and the anesthetic time was recorded. The data was analyzed with ANOVA and Chi-square test using SPSS12.2 software package. RESULTS: The anesthesia efficiency was 99% in group I, 98% in Group II, and 62% in Group III. The imagine quality in Group I and II was higher than that in Group III. For both anesthesia efficiency and imagine quality, there was no significant difference between Group I and Group II, but there was significant difference between Group I and Group III, and between Group II and Group III (P<0.01).Significant difference of anesthetic time was showed between Group I and Group II . Compared with Group II, longer time(4 minutes) was needed in Group I to show the anesthetic effect, and it lasted longer for 21.62+/-3.54 minutes; while in Group II, the anesthetic effect lasted shorter, only for 2.07+/-1.22 minutes, but it developed immediately. CONCLUSION: The use of local anesthetics improves the accuracy, quality, and success rate in taking dental X-ray films.