[Comparison of clear aligners and customized lingual appliance for bimaxillary dentoalveolar protrusion: a retrospective study].

PURPOSE: To compare the treatment effects of clear aligners and customized lingual appliance on treating bimaxillary dentoalveolar protrusion patients with first premolar extractions. METHODS: Fifty-four patients with bimaxillary dentoalveolar protrusion treated in Shanghai Ninth People Hospital were involved in the retrospective study. Twenty-five cases used clear aligners and 29 cases used customized lingual appliance. All of them were treated by extracting 4 first premolars and retracting anterior teeth with strong anchorage. The changes of anterior tooth and soft tissue adduction before and after treatment were compared by lateral cephalometric measurements. SPSS 26.0 software package was used for data analysis. RESULTS: The total course of treatment in the clear aligners group (46.32±7.37 months) was about 10.8 months longer than that in the customized lingual appliance group (35.55±5.90 months) (P＜0.05). There was no significant difference in upper incisor retraction, lower incisor inclination and overjet reduction between the two groups(P＞0.05). There were significant differences in upper lip retraction, lower lip retraction, upper incisor torque reduction, and overbite reduction between the two groups(P＜0.05). Customized lingual appliance group showed a significant improvement of lips retraction and overbite reduction in orthodontic treatment. For the correction of overjet, there was no significant difference between the two groups (P=0.337). The data of U1-OP (the distance between edge of the upper central incisor and the functional occlusal plane) was not in normal distribution, and there was no significant difference between the two groups(P=0.184). CONCLUSIONS: The two techniques can both retract the anterior teeth and lips to improve the profile. However, the customized lingual appliance was more effective in improving the soft tissue profile of patients with bimaxillary dentoalveolar protrusion, with shorter treatment course.

Antibacterial effects and tensile bonding strength of orthodontic adhesive containing nanohydroxyapatite / 口腔疾病防治

Objective @# To evaluate the tensile bonding strength (TBS) and antibacterial properties when an orthodontic adhesive was added with nanohydroxyapatite (nHAp). @*Methods@#Light cure orthodontic adhesive (Grengloo) was blended with 2% TiO2 containing nHAp nanoparticles by 0%、10%、20%、30% (w/w), while the control was not blended with nHAp. Brackets were bonded to extracted premolars by these new adhesives. TBS of 5groups were determined, and the adhesive remnant index (ARI) scores were assessed. Composite discs specimen were prepared, incubated with bacterial suspension for 48 h, and tested for antibacterial properties. @*Results @#No significant difference was found in ARI. The colony unit counts and lactate productionof the groups containing 2%TiO2 were significantly reduced. The colony unit counts and lactate production were without relationship with nHAp. The tensile bonding strength drastically decreased when containing more than 10% nHAp. @* Conclusin@#nHAp might not enhance the antibacterial effects of Grengloo.

[Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

[Study on cadmium absorption in pumpkin by atomic absorption spectrophotometry].

A study was carried out on the characteristic of cadmium absorption in pumpkin by atomic absorption spectrophotometer. The results show that the cadmium absorption amount in pumpkin increased with the increase in cadmium concentration. Meanwhile the cadmium absorption amount in pumpkin increased with time. Eight hours after being cultured in the liquid, the cadmium absorption amount became saturated. The cadmium absorption rate reached the peak after 2 hours, then the absorption rate gradually reduced. The cadmium absorption amount in pumpkin is less in acid or alkali compared with neutral condition. And the absorption amount became minimum in pH 3, while maximum in pH 7.