[Practice and experience in early clinical education of dental students in preventive dentistry].

To help dental students acquaint the medical environment, doctor-patient communication and relationship, early clinic education was arranged in our college of stomatology. The interesting topics were chosen to enhance the learning enthusiasm of the students in the teaching practice of preventive dentistry. Students were encouraged to practice the skill of doctor-patient communication. To obtain the satisfactory teaching effect and aim, it was important to pay attention to the aspects in the groups and clinical practice. Early clinic education in preventive dentistry help the students understand the specialty of preventive dentistry.

A randomized trial on the inhibitory effect of chewing gum containing tea polyphenol on caries.

OBJECTIVE: The purpose of the study was to determine the cariostatic potential of a chewing gum containing tea polyphenol. STUDY DESIGN: A total of 157 schoolchildren aged 8-9 years were randomly allocated into three groups. Two groups received chewing gum with or without tea polyphenol. A third group did not receive any chewing gum. A single examiner assessed the caries status for all participates at baseline, 12 months and 24 months. A one-way analysis of variance (ANOVA) was performed to evaluate differences among the groups at each interval The Chi-square test was used to compare the caries-free rate among the three groups. RESULTS: The mean DMFT increment was 0.17 for the polyphenol gum group, 0.60 for the control gum group, and 1.15 for the no gum group. Children who chewed gum containing tea polyphenol had a significantly lower mean DMFS increment over the 24-month period than did the other two groups (p < 0.05). The caries-free rate in the polyphenol gum group was significantly higher than that in the other two groups (p < 0.05) after two years. CONCLUSION: These findings indicated that the oral application of chewing gum with tea polyphenol has an inhibitory effect on dental caries.

[Clinical evaluation of pit and fissure sealant with light-cured flowable resin and light-cured pit and fissure sealants].

PURPOSE: To evaluate the difference between light-cured flowable resin and light-cured pit and fissure sealant in the cost and retention rate of pit and fissure sealant treatment. METHODS: Two hundred and fifty six children aged from 7 to 10 years were selected in this study. Each of them had at least two caries-free first molars. One first molar was sealed with light-cured flowable resin and the other one was sealed with traditional light-cured sealant. The portable dental chair were used to absorb saliva and cotton rolls were applied for moisture control. The operation time and number of cotton rolls used were recorded. After one year, the reservation of material was checked by two dentists using explorer. All the procedures were undertaken in schools.The data were analyzed using SPSS10.0 software package. RESULTS: It took 3.53 minutes for one tooth to be sealed with traditional light-cured sealant and 3.32 minutes with light-cured flowable resin (P<0.05). The retention rate of the light-cured flowable resin group was significantly higher compared with traditional light-cured sealant group (P<0.05). CONCLUSION: Light-cured flowable resin can be used as fissure sealant to prevent caries in a shorter operation time used in schools.

[Effect of two kinds of chewing gums on dental plaque pH].

PURPOSE: The aim of the study was to evaluate the change of plaque pH after chewing 2 kinds of gums. METHODS: The investigation consisted of 8 healthy subjects (aged 23-27 years, 4 males and 4 females) who refrained from toothbrushing for 24 hours before the test. The pH of dental plaque was measured using a Beetrode pH microelectrode before and after sucrose challenge with a 10% sucrose solutions at 5, 10, 15, 20 minutes as the baseline data. One week later the pH of dental plaque was measured again before the rinse and then the subjects rinsed with a 10% sucrose solutions. After 1 minute the sugar-free chewing gum was given and started to chew for 5, 10, 15, 20 minutes. The pH of dental plaque was measured at the same time on the non-chewing side. One week later the same test was carried out but the chewing gum was changed to tea polyphenol gum. Dental plaque pH value were analyzed by one-way ANOVA and SNK using SPSS 10.0 software package. RESULTS: Compared with the baseline chewed either tea polyphenol gum or sugar-free gum could increase the plaque pH recovery due to the sucrose rinsing challenge and it could maintain the dental plaque pH above the resting value. There was no statistically significant difference between tea polyphenol gum and sugar-free gum (P>0.05). CONCLUSION: Both gums can increase the plaque pH and decrease the risk of caries.

[The effect of chewing gum containing tea polyphenol on salivary flow rate and pH].

PURPOSE: To investigate the change of saliva flow rate and pH after chewing tea polyphenol gum. METHODS: Saliva was collected before and after chewing tea polyphenol gum and the control gum. Both the salivary flow rate and pH value were measured and analyzed by one-way ANOVA and SNK. RESULTS: The chewing gum significantly increased the flow rate as well as pH value of the saliva. The flow rate of the tested and control gum reached peak in the first minute. They were 3.15+/-1.05 and 3.30+/-0.87 ml respectively. There was no significant difference between the chewing gums. CONCLUSION: Chewing gum can increase the secretion and elevate the pH value of the saliva which benefits oral health care.

[Orthodontic treatment for the impacted upper central incisors: report of 28 cases].

PURPOSE: To study the effect of treating the impacted upper central incisors which couldn't erupt by surgical exposure and orthodontic traction. METHODS: 28 cases with 30 impacted upper central incisors were treated with surgical exposure and orthodontic traction. RESULTS: In 1 case, the tooth erupted by traction. but the space was not enough, the child's parents refused extraction of the teeth, which resulted in malalignment of the maxillary incisors. In 1 case, the tooth erupted after 3 months of traction, but the patient gave up further treatment because he had no revisit time. In the remaining 26 cases all the teeth moved into correct position. The average eruption time was 4.5 month (rang: 1 to 10 months). 28 impacted teeth had vital pulp. No root absorption and conglutination were found. CONCLUSIONS: The time of treatment, reasonable orthodontic method, less operative trauma, appropriate traction force, anchorage, control of inflammation are the keys of successful treatment.