Simultaneous implantation and tooth preparation technology guided by 3D-printed guide.

Using digital technologies in concurrently performing missing tooth implantation and preparation of remaining teeth is a solution to reduce the number of visits and improve efficiency. This paper proposes a digital process for simultaneously implanting and preparing teeth. It integrates implant surgical guide and 3D-printed tooth preparation guide into a single guide and completes guided implant placement and precise tooth preparation. Based on "repair-oriented" virtual implant planning, the implant surgical guide can improve the efficiency and predictability of implant placement, and its linear accuracy is about 1 mm. The tooth preparation guide precisely guides tooth preparation and restoration space visualization, ensuring the quality of the tooth preparation. The two guides have different design accuracy requirements, and thus their combination improves the overall guiding accuracy requirements. The concurrent application of the two guides minimizes the clinical operation time, number of visits, and economic burden of patients.

First Report of the Root-Knot Nematode Meloidogyne enterolobii infecting Acalypha australis in China.

Copperleaf (Acalypha australis; Euphorbiaceae), widely cultivated in China, is a traditional Chinese herbal medicine that is used for clearing heat and detoxifying, astringency and hemostasis (Zhang and Zhang 1994). In September 2021, wild Asian copperleaf plants showed leaf yellowing in a corner outside a greenhouse (22°50' N; 108°17' E), Guangxi Province, China. Galls and egg masses were observed on the plant roots on approximately 60% of plants. Females and second-stage juveniles (J2) were dissected and extracted from roots with galls. The perineal pattern of females was dorsal-ventrally oval with low and round dorsal arches, lacking clear lateral lines. Morphological measurements of females (n=20; mean ± standard error) were body length (BL) 697.7 ± 17.3 µm, maximum body width (BW) 521.5 ± 18.3 µm, stylet length 14.8 ± 0.3 µm, and dorsal pharyngeal gland orifice to stylet base (DGO) 5.1 ± 0.2µm. J2s (n = 20) were vermiform, had a slender tail, with a tapering to rounded tip with distinct hyaline region at the tail terminus and had the following morphological measurements: BL 475.5 ± 32.7 µm, BW 16.7 ± 0.6 µm, stylet length 14.4 ± 1.4 µm, DGO 3.9 ± 0.1 µm, hyaline tail length 18.0 ± 0.6 µm, and tail length 50.1 ± 1.2 µm. These morphological characteristics fit the description for Meloidogyne enterolobii (Yang and Eisenback 1983). In order to confirm species identification, genomic DNA was extracted from 12 single J2 (Luo et al. 2020). Species identity was further explored by the rDNA-internal transcribed spacer (ITS) region using primers V5367/26S (Vrain et al. 1992), and the D2-D3 fragment of the 28S ribosomal RNA gene using primers D2A/D3B (De Ley et al. 1999). The sequences for the target genes were 733 bp (GenBank accession no. OM168996) and 734 bp (GenBank accession no. OM177195), respectively. Homologies were 99 to 100% identical with those in GenBank for known sequences of M. enterolobii. Furthermore, species identification was confirmed using PCR to amplify a portion of the rDNA-IGS2 with M. enterolobii-specific primers Me-F/Me-R (Long et al. 2006). Koch's postulates was tested in a greenhouse at 25 to 28˚C temperature. Eggs were multiplied on tomato in the greenhouse using a single egg mass hand-picked from originally natural infected A. australis roots. Fifteen A. australis seedlings maintained in 14.5-cm diameter and 10-cm high pots containing autoclaved sandy soil (sand/soil = 3:1), one seedling/pot, inoculated with 5,000 eggs/plant, and five noninoculated seedlings were used as controls. After 60 days, all inoculated plants showed galling root symptoms and the control plants displayed no symptoms. The reproduction factor (Rutter et al. 2021) on A. australis was 4.3. Furthermore, the morphological and molecular characterization of the nematode was identical to the original samples. To our knowledge, this is the first report of M. enterolobii infecting Asian copperleaf that is cultivated in 29 provinces/regions of China. The growers should be aware of this nematode and take measures to avoid spread and serious economic losses.

Enhancing Channel Contention Efficiency in IEEE 802.15.4 Wireless Networks.

Numerous Internet of Things (IoT) devices adopt the IEEE 802.15.4 standard, which targets low data rate wireless networks. With the explosive growth in the use of IoT devices, it is essential to design effective and efficient channel access schemes for the 802.15.4 networks. In order to improve channel contention efficiency (CCE), which is defined as the number of times of successfully gaining the channel per unit of backoff time whereby throughput is improved, the scheme of enhancing channel contention efficiency (ECCE) has been proposed to jointly optimize the three key parameters of macMinBe, macMaxBe and macMaxCsmaBackoffs in the carrier sense multiple access with collision avoidance (CSMA-CA) mechanism in the 802.15.4 standard. A novel Markov chain was developed to model the CSMA-CA mechanism, which yielded the expected number of failures in gaining the channel, the expected number of backoff periods and the expected number of backoffs when a node intended to transmit a packet. These statistics resulted in CCE. An optimization problem that maximized the CCE with respect to the above-mentioned three key parameters was formulated. The solution to the optimization problem led to the optimal parameter values, which were applied in the ECCE scheme. The simulation results show that the proposed ECCE scheme outperformed the CSMA-CA mechanism in terms of CCE, delay and throughput.

Shear bond strength of ceramic laminate veneers to finishing surfaces with different percentages of preserved enamel under a digital guided method.

BACKGROUND: The purpose of this in vitro study was to evaluate the effect of the percentages of preserved enamel on ceramic laminate veneers' (CLVs) shear bond strength (SBS). METHODS: Seventy extracted human maxillary central incisors were scanned and reconstructed into three-dimensional models. The extracted teeth were then embedded and randomly divided into seven groups (n = 10 per group). Based on digital analyses of the three-dimensional models, guided tooth preparation and bonding procedures were performed individually to form seven different percentages (100%, 80%, 60% 50%, 40%, 20% and 0%) of remaining enamel thickness on the bonding surface. Finally, the SBS test was performed, and the data were statistically analysed by one-way ANOVA with LSD post hoc test (α = 0.05). RESULTS: The complete enamel surface exhibited the highest SBS (19.93 ± 4.55 MPa), followed by 80% enamel (19.03 ± 3.66 MPa), 60% enamel (18.44 ± 3.65 MPa), 50% enamel (18.18 ± 3.41 MPa), 40% enamel (17.83 ± 3.01 MPa) and 20% enamel (11.32 ± 3.42 MPa) group. The lowest SBS (9.63 ± 3.46 MPa) was detected in 0% enamel group. No significant difference was observed among the 40-100% enamel groups, while the 20% or 0% enamel group demonstrated a significantly lower mean SBS than the 40% enamel group (p < 0.05). CONCLUSION: The SBS value of CLVs bonded to 100% enamel on the finishing surfaces (nearly 20 MPa) was twice that which bonded to 0% enamel (nearly 10 MPa). Bonding to 100% enamel is the most reliable treatment. When dentin exposure is inevitable, enamel should be preserved as much as possible to maintain good bonding. In addition, 40% of preserved enamel on the bonding surface was the minimal acceptable value to fulfil the requirements of good bonding strength.

Meloidogyne enterolobii risk to agriculture, its present status and future prospective for management.

Meloidogyne enterolobii, commonly known as guava root-knot nematode, poses risk due to its widespread distribution and extensive host range. This species is recognized as the most virulent root-knot nematode (RKN) species because it can emerge and breed in plants that have resistance to other tropical RKNs. They cause chlorosis, stunting, and yield reductions in host plants by producing many root galls. It is extremely challenging for farmers to diagnose due to the symptoms' resemblance to nutritional inadequacies. This pathogen has recently been considered a significant worldwide threat to agricultural production. It is particularly challenging to diagnose a M. enterolobii due to the similarities between this species and other RKN species. Identified using traditional morphological and molecular techniques, which is a crucial first in integrated management. Chemical control, biological control, the adoption of resistant cultivars, and cultural control have all been developed and effectively utilized to combat root-knot nematodes in the past. The object of this study was to get about the geographical distribution, host plants, symptoms, identification, and control techniques of M. enterolobii and recommend future initiatives to progress its management.

[Precise tooth preparation technique guided by 3D printing guide plate with quantitative hole].

The minimum amount of tooth preparation that can be fully controlled is crucial in achieving long-term, stable, and effective aesthetic restoration, which is also a major difficulty in aesthetic restoration. The tooth preparation can be imple-mented efficiently and accurately through digital technology based on the fixed-deep hole guiding technology. Prior the actual tooth preparation, the technology first designs the virtual contour, layering, and virtual occlusion of the prosthesis on the computer. Then, virtual tooth preparation is carried out by cutting back according to the virtual prosthesis. Next, the virtual drilling operation plan is designed according to the shape of the virtual tooth preparation and the contour of the abutment tooth. Finally, the tooth preparation guide plate is designed and printed in 3D. It realizes the whole process of quantitative and precise guidance of dental preparation, visualizes the restoration space, reduces the clinical operation time, and guarantees the quality of dental preparation. It also promotes the improvement of the teaching quality of digital practical exercises.

[Precise implant insertion technology for measuring dental implant placement].

Identifying the ideal implantation site is important for the long-term stability and effectiveness of follow-up restorations. Implant surgical guide and navigation are used to determine the implantation site in clinic and improve the precision of implantation. However, due to difficulties in digital methods, such as multiple procedures, high cost, and actual accuracy of more than 1 mm, many physicians still prefer to operate with free hand. In preoperative, intraoperative, and postoperative procedures, time-saving and practical methods for implant site evaluation are lacking. In many cases, oral physicians found that the position deviates only by cone beam CT, which was costly to modify the position. In this article, we presented a precise implantation insertion technology that is guided by a measurable technique throughout the implantation application for all implant systems. This method was guided by a dynamic control measuring ruler, which functions together with the measuring and intraoperative locating rulers. The 3D space of the operative area was measured by a measuring ruler prior to operation, and the implant plan and quantitative guidance design were conducted according to the measured and cone beam CT data. The whole implantation process was guided by the dynamic control measuring ruler, and measuring verification results were also considered. This method can realize the quantification of the entire preoperative space analysis, intraoperative precise implantation guidance, and postoperative site measurement and evaluation. This practical technique also helps to adjust the position, improve the implantation accuracy and is suitable in generalizing dental implantation.