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Background and Objectives: Osteoprotegerin (OPG), a soluble glycoprotein found in serum, has been associated with both the presence and severity of atherosclerosis. OPG is regarded as the mediator in the process of vascular endothelial dysfunction. Impaired endothelial function has an intimate link with hypertension (HTN) and is associated with significant morbidity and mortality. This study was to investigate the connection between OPG and endothelial dysfunction in patients having HTN. Materials and Methods: There are 102 patients with HTN included. For the purpose of determining the levels of OPG, a commercial enzyme-linked immunosorbent test kit was applied. The vascular reactivity index (VRI), which is assessed via the digital thermal monitoring, provides information on endothelial function. Results: Ten patients with HTN (9.8%) were classified as having poor vascular reactivity (VRI < 1.0), 46 HTN patients (45.1%) as having intermediate vascular reactivity (1.0 ≤ VRI < 2.0), and 46 HTN patients (45.1%) were classified as having high vascular reactivity (VRI ≥ 2.0). A greater serum OPG level (p < 0.001) and older age (p = 0.022) were linked to impaired vascular reactivity. The estimated glomerular filtration rate (r = 0.196, p = 0.048) was positively correlated with VRI values in hypertensive participants, while advanced age (r = −0.222, p = 0.025) and the log-transformed OPG level (log-OPG, r = −0.357, p < 0.001) were negatively correlated with VRI. Serum log-OPG level was shown to be strongly and independently correlated with VRI values in HTN individuals after multivariable forward stepwise linear regression analysis (β = −0.357, adjusted R2 change = 0.119, p < 0.001). Conclusions: In patients with HTN, serum OPG levels were adversely correlated with VRI and probably had a role in endothelial dysfunction.

In terms of fracture mechanics, a precrack preparation may facilitate the propagation of a break through the expected fracture plane during the bracket debonding process. The purpose of this study was to evaluate the effect of an ultrasonic precrack preparation on the debonding force and failure modes of ceramic bracket removal. Methods: Eighty extracted premolars were assigned to four groups: Inspire, precrack Inspire, Clarity, and precrack Clarity groups, with each group containing 20 teeth. The precrack preparations were made at the mesial gingival line angle of Inspire brackets and on the mesial side of Clarity brackets with an ultrasonic tip. Debonding force, failure modes, and bracket breakage score were measured and recorded. Fracture surfaces after bracket debonding were observed with scanning electron microscopy (SEM). Results: We found that the ultrasonic precrack preparation could significantly decrease the average debonding force and the mean bracket breakage scores of both kinds of ceramic brackets. After bracket debonding, 80% of brackets in the precrack Inspire group and 100% of brackets in the precrack Clarity group showed no bracket failure. However, only 25% of brackets in the Inspire group and 75% of brackets in the Clarity group showed no bracket failure. SEM micrographs showed a precrack notch at the adhesive resin after precrack preparation, and no enamel damage was noted after the bracket debonding. Conclusion: The ultrasonic precrack preparation can significantly decrease the debonding force and may guide the bracket debonding through a favorable fracture plane without damage to either the bracket or the enamel.

Background/purpose: Ultrasonic instruments are commonly used in dentistry because of their safety, acceptance by patients, ease of viewing the surgical area, and highly precise cutting. However, they do not efficiently remove enamel. The aim of this study is to optimize the surface coating parameters of an ultrasonic diamond grinding tip for enamel removal. Materials and methods: The experiments were conducted using a triple-axle precision moving platform. The ultrasonic handpiece was mounted on the platform column, and powered by an ultrasonic device with a voice coil motor providing a uniform down force of 2 N to grind adult molar specimens. The commercially available diamond tips UL3A (Cur scaler, Bonart, Taiwan) and EX1 (Newtron, Acteon, France) were used in this study. The Taguchi method and analysis of variance were used to determine the optimal surface parameters (mesh size, crystal shape, protrusion, and crystal density) of dental diamond tips. By using the optimal surface characteristics, new tips N1 and N2, having the same geometrical shape and dimension of UL3A and EX1, respectively, were fabricated and their grinding performance was tested. Results: The optimal enamel removal parameters of the grinding tip are diamonds of 100/120 mesh size, shape of well-formed crystal facet, 75 μm protrusion, and density of 45 crystals per square millimeter surface area. The material removal rate (MRR) of enamel for N1 (UL3A with new characteristics) is 0.064 mm3/s, 3.4 times that of the original UL3A tips. For N2 (EX1 with new characteristics) it is 0.126 mm3/s, which is 3.2 times that of the original EX1 tips. Conclusion: Protrusion, shape, and density of diamonds of an ultrasonic dental tip are significantly related to the MRR of enamel, and the optimal combination of these parameters is obtained. Knowledge of the importance of these variables will help in more effective use of the ultrasonic technology in dentistry.

Background/purpose: The aim of this study was to evaluate the pulp–dentin response after pulp chamber perforation by ultrasonic and high-speed air-driven devices. Materials and methods: Eighteen upper incisors from nine dogs were used in this study. We prepared Class V cavity (3 × 5 mm) at the labial side after anesthesia. The pulp was then exposed/perforated by either an ultrasonic or high-speed air-driven device. We evaluated the hemorrhage condition by stopping the bleeding with varying numbers of sponge pellets. Three observation time points were set: immediate, 1 week (1-wk), and 2 weeks (2-wk). Then, we evaluated the pulp–dentin response using scanning electronic microscopy (SEM) and histological examination. Results: The bleeding level caused by an ultrasonic device presented as either no bleeding or mild bleeding, and a high-speed air-driven bur caused worse bleeding conditions. The ultrasonic group showed better response in the immediate pulpal response. In 1 week, both methods presented no pulp necrosis, and those treated using the ultrasonic device presented with a regular odontoblastic layer under SEM observations. In the 2-wk group, both methods showed no pulp necrosis, whereas the high-speed device showed partial necrosis. SEM showed pulp tissue with lacerated wounds in those who had the high-speed device treatment. Conclusion: We conclude that the ultrasonic device causes less damage to the dental pulp tissue in comparison with the high-speed air-driven bur. Moreover, we expect that the ultrasonic device can be applied to vital pulp therapy—such as direct pulp capping, pulptotomy, or pulpectomy—due to its safe approach.

Background/purpose: Ultrasonic osteotomy has been introduced in oral and maxillofacial surgery in recent years for minimally invasive treatment. The purpose of this study is to evaluate the cutting performance of three different coated tips by the material removal rate (MRR) measurement and the temperature rise (TR) investigation in ultrasonic osteotomy. Materials and methods: Three stainless steel tips with different coated treatments to have the coefficients of friction of 0.5, 0.4, and 0.1 for uncoated tip, titanium nitride (TiN) coated tip, and diamond-like carbon (DLC) coated tip, respectively, were tested. The tip was fixed in the hand-piece and powered by an ultrasonic device (Cur scale, Bonart, Taiwan) with power mode of 40, 45 and 50. The ultrasonic hand-piece was mounted on the column of the X-Y table, and a uniform down force of 3 N was provided by the voice coil motor. A groove on the bovine bone specimen was obtained as a result of the downward action together with ultrasonic vibration of the tip. The MMR and TR were measured and evaluated. Results: The average MMR for the DLC coated tip under the operation mode 50 of the ultrasonic device was 0.164 mm3/s as compared with 0.153 mm3/s of TiN coated tip and 0.147 mm3/s of the uncoated tip. The average TR in 60 seconds operation was 8.1°C for the uncoated tip, 6.8°C for the TiN coated tip, and 4.5°C for the DLC coated tip. Conclusion: The DLC coated tip leads to the highest material removal rate and least temperature rise among the three types of tip under study. This is due to its low coefficient of friction and less power is needed to overcome the friction force in ultrasonic osteotomy.

Since the 1950s, dentistry's ultrasonic instruments have developed rapidly. Because of better visualization, operative convenience, and precise cutting ability, ultrasonic instruments are widely and efficiently applied in the dental field. This article describes the development and improvement of ultrasonic instruments in several dental fields. Although some issues still need clarification, the results of previous studies indicate that ultrasonic instruments have a high potential to become convenient and efficient dental tools and deserve further development.

Background/purpose: The purpose of this study was to investigate whether the use of piezoelectric instruments affected the healing propensity of alveolar sockets after mandibular third molar extraction, compared with conventional rotary instruments. Materials and methods: Thirty patients with impacted bilateral symmetrical mandibular third molars participated in this investigation. We conducted a randomized, crossover study using conventional rotary instruments for extraction on one side and piezoelectric instruments on the other. We evaluated the healing of periodontium at the distal side of the mandibular second molar by probing depth and attachment level. All data including pocket depth and bone healing at the distal side of the mandibular second molar were evaluated with paired t tests for comparison. Results: Although the average pocket depth after extraction with piezoelectric instruments was slightly less than with conventional instruments, there was no statistically significant difference between the two groups. At one month after extraction, the attachment level at the distal side of the mandibular second molar was better where extraction was done with piezoelectric instruments than conventional instruments (P

A novel chitosan-γPGA polyelectrolyte complex hydrogel (C-PGA) has been developed and proven to be an effective dressing for wound healing. The purpose of this study was to evaluate if C-PGA could promote new bone formation in the alveolar socket following tooth extraction. An animal model was proposed using radiography and histomorphology simultaneously to analyze the symmetrical sections of Wistar rats. The upper incisors of Wistar rats were extracted and the extraction sockets were randomly treated with gelatin sponge, neat chitosan, C-PGA, or received no treatment. The extraction sockets of selected rats from each group were evaluated at 1, 2, 4, or 6 wk post-extraction. The results of radiography and histopathology indicated that the extraction sockets treated with C-PGA exhibited lamellar bone formation (6.5%) as early as 2 wk after the extraction was performed. Moreover, the degree of new bone formation was significantly higher (P < 0.05) in the extraction sockets treated with C-PGA at 6 wk post-extraction than that in the other study groups. In this study, we demonstrated that the proposed animal model involving symmetrical sections and simultaneous radiography and histomorphology evaluation is feasible. We also conclude that the novel C-PGA has great potential for new bone formation in the alveolar socket following tooth extraction.

We developed an automatic debris flow warning system in this study. The system uses a fixed video camera mounted over mountainous streams with a high risk for debris flows. The focus of this study is to develop an automatic algorithm for detecting debris flows with a low computational effort which can facilitate real-time implementation. The algorithm is based on a moving object detection technique to detect debris flow by comparing among video frames. Background subtraction is the kernel of the algorithm to reduce the computational effort, but non-rigid properties and color similarity of the object and the background color introduces some difficulties. Therefore, we used several spatial filtering approaches to increase the performance of the background subtraction. To increase the accuracy entropy is used with histogram analysis to identify whether a debris flow occurred. The modified background subtraction approach using spatial filtering and entropy determination is adopted to overcome the error in moving detection caused by non-rigid and similarities in color properties. The results of this study show that the approach described here can improve performance and also reduce the computational effort.