[Maxillary dental and palatal morphological characteristics in 62 children with impacted maxillary canine in mixed dentition].

PURPOSE: The aim of this study was to compare the difference of dental arch and palatal morphology between children with impacted maxillary canine and without impacted maxillary canine, to provide reference for early diagnosis and treatment of impacted maxillary canine. METHODS: Sixty-two children, 8-11 years of age (9.8±1.04 years), were divided into experimental group and control group, with 31 children in each group. Digital casts were obtained using 3D laser scanner from maxillary models. Dental arch width, length, basal bone width, palatal width, height, surface area and volume were measured. Paired t test was performed with SPSS 24.0 software package. RESULTS: Dental arch width and palatal width were significantly narrower in experimental group than in control group(P<0.05), but there was on significant difference in dental arch length, basal bone width and palatal height between the two groups(P>0.05).Additionally, palatal surface area and volume were significantly larger in control group than in experimental group(P<0.05). CONCLUSIONS: Children with impacted maxillary canine have smaller maxillary dental arch width, palatal width, palatal surface area and volume compared to control group. Dental arch width, palatal width, palatal surface area and volume should be taken into consideration when early identifying impacted maxillary canine.

[Three-dimensional morphological analysis of the palate of mouth-breathing children in mixed dentition].

OBJECTIVE: To study the effects of mouth-breathing on maxillary arch development by comparing the palatal morphology of mouth- and nose-breathing children in mixed dentition. METHODS: Children in mixed dentition were enrolled and categorized into mouth-breathing (test group) and nose-breathing groups (control group) according to their breathing patterns. Children's plaster models were scanned with 3D laser scanner, and the 3D data were reconstructed and measured using Minics 15.0 and Geomagic 12.0 software. Measurement data (inter-molar width, palatal height, palatal volume, and palatal surface area) of the two groups were compared, and the correlation among the four measurement items was analyzed. RESULTS: The participants were 73 children (37 in test group and 36 in control group) with a mean age of (8.63±0.78) years old. The test group had significantly smaller inter-molar width, palatal volume, and palatal surface area but significantly higher palatal height than the control group (P<0.05). Inter-molar width and palatal volume were positively correlated with the palatal surface area in the test group (P<0.05). Inter-molar width and palatal height were positively correlated with the palatal surface area in the control group (P<0.01). CONCLUSIONS: Mouth-breathing children have significantly reduced inter-molar width, palatal volume, and surface, and substantially increased palatal height, leading to different developmental patterns of the palatal morphology.

[Evaluation of the clinical effect of fluoride varnish in preventing caries of primary teeth].

OBJECTIVE: To evaluate the clinical effect of fluoride varnish in preventing caries of primary teeth, and to compare the caries prevention effects of fluoride varnish with two different concentrations. METHODS: 150 children whose ages were three year-old were randomly chosen from one of nurseries of Chongqing, and were randomly divided into four groups with 37 children in 0.5% fluoride varnish group, 38 children in 0.1% fluoride varnish group, 39 children in 0.5% sodium fluoride group and 36 children in blank group. The groups included 71 'girls and 79 boys. Protective measure was applied every half an year and the research has lasted for two years. The research was designed by double-blinded methods, and was carried out with the dental caries standard suggested by World Health Organization. All the data were collected and the clinical effects of four groups were compared. RESULTS: The average caries index and caries surface index of 0.1% fluoride varnish group and those of control groups were significantly higher than that of 0.5% fluoride varnish group. There were no significant difference between the average caries index and caries surface index of 0.1% fluoride varnish group and those of control groups. CONCLUSION: 0.5% fluoride varnish was effective in preventing caries of primary teeth.

[Establishment of malodor model and its effects on identifying the halitosis-related bacteria].

OBJECTIVE: To establish a salivary sediment malodor system, and to evaluate the effect of several kinds of bacteria dedicated to the halitosis formation, hence to identify halitosis-correlated bacteria. METHODS: The proportion of the supernatant and sediment, gained from centrifugal whole saliva, was adjusted to establish a salivary sediment malodor system incubated in facultative aerobic environment under 37 degrees C for 7 hours. The halitosis indexes in both gaseous phase and liquid phase were checked by direct sniffing, and volatile sulphur compounds (VSCs) and pH were determined by halimeter and glass electrode respectively between hours to evaluate the malodor formation. The suspended fluid of suspicious halitosis-correlated bacteria and non-halitosis-correlated bacteria and water control were introduced into the salivary sediment system incubated for 1 hour. The five groups were incubated in facultative aerobic environment under 37 degrees C in the residual hours. The halitosis indexes, VSCs and pH changes were recorded between hours. RESULTS: The salivary sediment malodor system can simulate the metabolism of halitosis formation to produce halitosis. The odors of the suspicious halitosis-correlated bacteria introduced groups were higher than the non-halitosis-correlated bacteria and water control group. CONCLUSION: With its simple but fundamental manipulations, incubated whole saliva is a powerful model for study of the metabolism of the oral mixed microbial flora, malodor formation, and other oral diseases-related processes.