Augmented reality guided in reconstruction of mandibular defect with fibular flap: A cadaver study.

BACKGROUND: Augmented reality (AR) navigation has been developed in recent years and can overcome some limitations of existing technologies. This study aimed to investigate a novel method of fibula free flap (FFF) osteotomy based on AR technology through a cadaver study. METHODS: One mandible, seven fibulas, and seven lower limb specimens underwent computed tomography (CT) examination. We used the professional software Proplan CMF 3.0 to design a defective mandible model and created fourteen virtual reconstruction plans using the fibulas and lower limb specimens. The AR-based intraoperative guidance software prototype was developed using the Unity Real-Time Development Platform, and virtual plans were transferred into this software prototype. We used AR-based surgical navigation to guide the FFF osteotomy and used these fibular segments to reconstruct the defective mandible model. After reconstruction, all segments were scanned by CT. Osteotomy accuracy was evaluated by measuring the length and angular deviation between the virtual plan and the final result. The reconstruction precision was reflected by the volume overlap rate and average surface distance between the planned and obtained reconstruction. RESULTS: The length difference, angular deviation, volume overlap rate and average surface distance of the in vitro group were 1.03±0.68 mm, 5.04±2.61°, 95.35±1.81%, and 1.02±0.27 mm, respectively. Those of the in vivo group were 1.18±0.84 mm, 5.45±1.47°, 95.31±2.09%, and 1.22±0.12 mm. CONCLUSIONS: Due to the ideal result of cadaver experiments, an AR-based FFF osteotomy guided system may become a novel approach to assist FFF osteotomy for the reconstruction of defective mandibles.

[A Sampling Survey of the Oral Health Status and Awareness among Primary School Students in Lhasa].

Objective To investigate the oral health status and awareness of urban children in Lhasa,aiming to provide a data basis for the prevention and treatment of children's caries and the promotion of oral health education. Methods A total of 504 Tibetan students were selected by cluster sampling from 2 primary schools in Chengguan District of Lhasa.All the participants were required to take oral health examination and complete a questionnaire about oral health awareness and behavior. Results The caries prevalence rate and mean decayed-missing-filled tooth(DMFT)of permanent teeth were 75.00% and 2.18±1.91,respectively.The rates of pit and fissure sealant and filling of permanent teeth were 3.77% and 6.81%,respectively.The caries prevalence rate of first permanent molars was 47.62%.The mean DMFT of permanent teeth and caries prevalence rate of first permanent molar were significantly higher in female group(P=0.001 and P=0.007,respectively).The prevalence rate of dental fluorosis was 61.51%,and the detection rate of dental calculus was 71.83%.Multivariate logistic regression analysis showed that prevalence of caries was influenced by many independent factors including gender,oral health awareness,intention of dental intervention,and dental experience. Conclusion High caries prevalence rate,low filling rate,and poor oral hygiene and health awareness were found among the primary school students in Lhasa,which require continuous dentistry investment and oral health education for the local students and their parents.

Improved performance of soy protein adhesive with melamine-urea-formaldehyde prepolymer.

In recent years, soy protein adhesive, as an environmentally friendly bio-based adhesive, has attracted extensive attention. In this study, in order to ameliorate the bonding quality of soy protein isolate (SPI) adhesive, the melamine-urea-formaldehyde prepolymer (MUFP) was synthesized, and different amounts of it were introduced into the SPI adhesive as a cross-linking agent. Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analyze (TGA), and scanning electron microscopy (SEM) were used to analysis the mechanism of modification. The results of plywood test indicated that the wet bonding strength of the adhesives was first increased and then decreased with an increase in the amount of MUFP additive. FT-IR, TGA, and SEM tests suggested that the introduction of MUFP could promote the establishment of a cross-linking structure in the cured adhesive layer to improve the bonding quality of adhesives, but presence of excessive MUFP could introduce hydrophilic groups and adversely affect water resistance.

Kinetics and Thermodynamic Analysis of Recent and Ancient Buried Phoebe zhennan Wood.

Kinetics and thermogravimetric analysis of recent Phoebe zhennan wood (RZ) and ancient buried P. zhennan wood (ABZ) were investigated under a nitrogen atmosphere at different heating rates of 5, 10, 15, and 20 K/min. The activation energy values were estimated based on the Flynn-Wall-Ozawa model-free method, and then, the Coats-Redfern model-fitting method was used to predict the reaction mechanism. The best model of RZ for regions 1 and 2 was based on the diffusional and reaction order (second-order) mechanism, respectively, while a diffusional (Jander equation) mechanism is the best model for ABZ. The change in enthalpy and activation energy of the RZ was lower than that of the ABZ at different conversion rates. When the conversion rate was less than 0.4, the RZ may require lower thermal decomposition reaction energy, but the overall energy of thermal decomposition reactions and the degree of disorder was not much different.