A mussel-inspired film for adhesion to wet buccal tissue and efficient buccal drug delivery.

Administration of drugs via the buccal route has attracted much attention in recent years. However, developing systems with satisfactory adhesion under wet conditions and adequate drug bioavailability still remains a challenge. Here, we propose a mussel-inspired mucoadhesive film. Ex vivo models show that this film can achieve strong adhesion to wet buccal tissues (up to 38.72 ± 10.94 kPa). We also demonstrate that the adhesion mechanism of this film relies on both physical association and covalent bonding between the film and mucus. Additionally, the film with incorporated polydopamine nanoparticles shows superior advantages for transport across the mucosal barrier, with improved drug bioavailability (~3.5-fold greater than observed with oral delivery) and therapeutic efficacy in oral mucositis models (~6.0-fold improvement in wound closure at day 5 compared with that observed with no treatment). We anticipate that this platform might aid the development of tissue adhesives and inspire the design of nanoparticle-based buccal delivery systems.

Influence of pontic design on speech with an anterior fixed dental prosthesis: A clinical study and finite element analysis.

STATEMENT OF PROBLEM: Patients may experience disturbed articulation after treatment with a fixed dental prosthesis. However, studies that assess the relationship between fixed dental prosthesis design and the accuracy of speech sound production are lacking. PURPOSE: The purpose of this clinical and finite element analysis (FEA) study was to examine the influence of pontic design on speech with anterior fixed dental prostheses. MATERIAL AND METHODS: First, an articulation test was carried out in which a partially edentulous participant was required to pronounce 4 Chinese words containing the voiceless fricative/s/while wearing fixed dental prostheses with 2 types of pontic designs. The oral morphology was obtained by cone beam computed tomography (CBCT) scanning while the participant, wearing the 2 fixed dental prosthesis designs, was pronouncing the voiceless fricative/s/sound. The geometry of the oral cavity was then reconstructed by an image processing software program. Finally, a finite element model for sound wave propagation inside the oral cavity was developed within the framework of the finite element analysis software program. By using this model, the sound pressure level of the 2 types of pontic design was characterized and quantified under different fundamental frequencies (F0). The data were analyzed with 1-way ANOVA (α=.05). RESULTS: The experimental articulation test reported that the pontic design of fixed dental prostheses affected the speech production of the/s/sound (P<.001). The numerical study reported that the sound pressure level values were different under various fundamental frequencies. In addition, the pontic design of fixed dental prostheses affected the sound pressure level values, and the differences varied significantly from 420 to 1300 Hz (P<.05); however, the differences were not significant between 120 and 420 Hz (P>.05). Moreover, further comparisons of low F0 (120 to 500 Hz), medium F0 (520 to 900 Hz), and high F0 (920 to 1300 Hz) reported that the differences in the medium F0 area were most obvious (P<.001 for maximum sound pressure level value and P=.001 for sound pressure level value at Point Q). CONCLUSIONS: Both the fixed dental prosthesis pontic design and the fundamental frequency could affect the sound field distribution.

An evaluation of fluid distribution at the implant site during implant placement by using a computational fluid dynamics model.

STATEMENT OF PROBLEM: Heat reduction during implant site preparation is critical. However, studies that assess fluid distribution at the implant site by using saline irrigation as the cooling method during osteotomies are lacking. PURPOSE: The purpose of this study was to evaluate the effect of various parameters on fluid distribution at the implant site by using a computational fluid dynamics numerical model and thus predict the cooling effect at the drill site. MATERIAL AND METHODS: The computational fluid dynamics code Flow-3D was adopted to simulate implant site preparation. A 10-mm-deep implant site was prepared by using a 2.2-mm pilot drill, with 4 °C saline sprayed onto the drill from an external injection hole. Different drilling procedures were performed with irrigation volumes of 20, 40, 60, and 80 mL/min at various drill speeds (600, 800, 1000, 1200 rpm) and feed rates (0.5, 1.0, 1.5, 2.0 mm/s), and the fluid distribution under various circumstances was respectively investigated and compared. Data were analyzed by using 1-way ANOVA or the Friedman test according to the normality of the data distribution (P>.05). RESULTS: Below the irrigation volume of 60 mL/min, the saline inside the implant site increased with the irrigation volume (P<.001), but further increase in irrigation volume to 80 mL/min had no significant influence on the fluid distribution (P>.05). The obtained fluid had an inverse relationship with the drill speed under the irrigation volumes 20 and 40 mL/min (P<.001), and deeper areas received less cooling under 20 mL/min (P<.001). However, no significant differences were observed under 60 and 80 mL/min (P>.05). In addition, the variation of feed rate had no significant effect on the mean fluid fraction for all the tested groups (P>.05). CONCLUSIONS: The fluid distribution at the implant site could be affected by the irrigation volume and drill speed but was not correlated with the feed rate.

Evaluation of needle movement effect on root canal irrigation using a computational fluid dynamics model.

BACKGROUND: Irrigation is considered to be a critical part of root canal treatment. However, little is known about the effect of needle movement on the irrigation process. Therefore, this study aimed to investigate the influence of the syringe and needle movement on root canal irrigation using a three-dimensional computational fluid dynamics (CFD) numerical model. METHODS: The CFD codes Flow-3D was adopted to simulate the root canal irrigation process with the syringe and needle moving up and down in motions at different amplitudes and frequencies. One stationary needle was adopted to allow comparison with the needles in up-and-down motions. Six cases where the needles were moving up and down with different amplitudes and frequencies were used to investigate the relationships between the motion of needle and irrigation efficacy. RESULTS: The stationary needle gained relatively higher flow velocity and apical pressure all through the irrigation process, while the needles in constant up-and-down motions exhibited lower mean flow velocity and apical pressure. The larger the amplitude, the less mean flow velocity and apical pressure were developed. In addition, the needles moving with different frequencies were similar in the terms of irrigant replacement and apical pressure. CONCLUSIONS: To avoid periapical extrusion accidents while obtaining adequate irrigant replacement, the needle should be moving up and down with a moderate amplitude during manual root canal irrigation; and the motion frequency was not highly relevant in terms of the irrigation efficiency.