Effect on implant drills and postoperative reactions for pre-extraction interradicular implant bed preparation during the COVID-19 pandemic and beyond.

The aim of the present study was to observe the abrasion of implant drills and postoperative reactions for the preparation of the interradicular immediate implant bed during the COVID-19 pandemic and beyond. Thirty-two implant drills were included in four groups: blank, improved surgery, traditional surgery, and control. In the improved surgery group, a dental handpiece with a surgical bur was used to decoronate the first molar and create a hole in the middle of the retained root complex, followed by the pilot drilling protocol through the hole. The remaining root complex was separated using a surgical bur and then extracted. Subsequently, the implant bed was prepared. Implant drills were used in the traditional surgery group to complete the decoronation, hole creation, and implant-drilling processes. The tooth remained intact until the implant bed was prepared. The surface roughness of the pilot drill was observed and measured. Surgery time, postoperative reactions (swelling, pain, and trismus), and fear of coronavirus disease 2019 scale (FCV-19S) were measured and recorded, respectively. Statistical analysis revealed significant difference with surface roughness among blank group (0.41 ± 0.05 µm), improved surgery group (0.37 ± 0.06 µm), traditional surgery group (0.16 ± 0.06 µm), and control group (0.26 ± 0.04 µm) (P < .001). Significant differences were revealed with surgery time between improved surgery group (5.63 ± 1.77 min) and traditional surgery group (33.63 ± 2.13 min) (P < .001). Swelling, pain, and trismus (improved group: r ≥ 0.864, P ≤ .006; traditional group: r ≥ 0.741, P ≤ .035) were positively correlated with the FCV-19S. This study proved that a new pilot drill could only be used once in traditional surgery but could be used regularly in improved surgery. Improved surgery was more effective, efficient, and economical than the traditional surgery. The higher FCV-19S, the more severe swelling, pain, and trismus.

Selectively Tracking Nanoparticles in Aquatic Plant Using Core-Shell Nanoparticle-Enhanced Raman Spectroscopy Imaging.

Nanoparticles contribute to enormous environmental processes, but, due to analytical challenges, the understanding of nanoparticle fate remains elusive in complex environmental matrices. To address the challenge, a core-shell nanoparticle-enhanced Raman spectroscopy (CSNERS) imaging method was developed to selectively track prevalent SiO2 nanoparticles in an aquatic plant, Lemna minor. By encapsulating gold nanoparticles and Raman reporters inside, the resonance Raman signature was enhanced, thus enabling the sensitive and selective detection of SiO2 nanoparticles at an environmentally relevant concentration. The panoramic visualization of the translocation pathway of nanoparticles shows an unexpected, fast (in hours) and a preferential accumulation of nanoparticles on the node, leaf edge, root cap, etc., implying the ability of CSNERS to spectroscopically determine nanotoxicity. The core-shell design in CSNERS was capable of multiplex labeling two differently charged nanoparticles and distinguishing their biobehavior simultaneously. Meanwhile, the CSNERS method can be further applied for a variety of nanoparticles, implying its promising applications for nanotoxicity research and biogeochemical study.

Serum Gamma-glutamyl Transferase Levels Predict Functional Outcomes after Aneurysmal Subarachnoid Hemorrhage.

OBJECTIVE: We aim to explore the potential association between serum gamma-glutamyl transferase levels and functional outcome after aneurysmal subarachnoid hemorrhage in a Chinese population. METHODS: A total of 386 aneurysmal subarachnoid hemorrhage patients were included in the study from September 2007 to February 2015. Baseline serum gamma-glutamyl transferase levels and 6-month follow-up functional outcomes were determined. A poor outcome was defined as a modified ranking scale score of ⋝ 3. The multivariable logistic model was used to analyze the relationship between serum gamma-glutamyl transferase and clinical outcomes after aneurysmal subarachnoid hemorrhage. RESULTS: The adjusted poor outcome rates of patients with gamma-glutamyl transferase levels of < 30 U/L, 30-50 U/L and ⋝ 50 U/L were 16.7%, 19.6%, and 34.4%, respectively (P < 0.01). The age-sex and multivariable adjusted odds ratios (95% confidence intervals) of poor prognosis comparing the top group (⋝ 50 U/L) with the lowest group (< 30 U/L) were 5.76 (2.74-12.13), 6.64 (2.05-21.52), and 6.36 (1.92-21.02). A significant linear trend existed between gamma-glutamyl transferase level and aneurysmal subarachnoid hemorrhage prognosis. This association was also observed among nondrinkers. CONCLUSION: Patients with higher gamma-glutamyl transferase levels were more likely to have a poor prognosis. Serum gamma-glutamyl transferase can be considered to be an independent predictor of functional outcomes after aneurysmal subarachnoid hemorrhage.

Early osseointegration of implants with cortex-like TiO2 coatings formed by micro-arc oxidation: A histomorphometric study in rabbits.

In our previous studies, a novel cortex-like TiO2 coating was prepared on Ti surface through micro-arc oxidation (MAO) by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment were testified. This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration. A sand-blasting and acid-etching (SLA) coating that has been widely used in clinical practice served as control. Topographical and chemical characterizations were conducted by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, contact angle meter, and step profiler. Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic, whereas the SLA surface was hydrophobic. The roughness of MAO was similar to that of SLA. The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT, histological analysis, and fluorescent labeling at the bone-implant interface four weeks after surgery. The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation. Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces. It was suggested that with micro/nanostructure and superhydrophilicity, the cortex-like MAO coating causes excellent osseointegration, holding a promise of an application to implant modification.

[Treatment of intercondylar fracture of the humerus through internal and external elbow approach or elbow posterior olecranon osteotomy approach].

OBJECTIVE: To investigate the efficacy, advantages and disadvantages of internal and external elbow joint approach and olecranon osteotomy approach for the treatment of intercondylar fracture of humerus. METHODS: From October 2012 to May 2016, 18 cases of intercondylar fracture of humerus were treated by operation including 12 males and 6 females with a mean age of 33.5 years old (ranged from 4 to 56 years old); 8 cases were operated by internal and external elbow joint approach, 10 cases were operated by olecranon osteotomy approach. According to AO classification, 3 cases were type C1, 8 cases were type C2, 7 cases were type C3. All patients were excluded from neurologic and vascular injuries. RESULTS: All patients were followed up from 12 to 26 months with an average of 15 months. The incision healed well and no heterotopic ossification was found. According to the modified Cassebaum elbow function score, the result was excellence in 14 cases, good in 3 cases, fair in 1 case. CONCLUSIONS: According to the fracture type, the appropriate surgical approach and fixation were selected in order to get anatomic reduction. Rigid fixation, and early functional exercise is important condition for successful operation and satisfactory functional recovery in intercondylar fracture of the humerus.

The Past, Present, and Future of Dentoalveolar Surgery in China.

Dentoalveolar surgery, formerly known as dental surgery or oral surgery, is one of the basic branches of oral and maxillofacial surgery. While it has a long history; however, there are great differences in its evolution globally. This article presents a brief review on the development of dentoalveolar surgery internationally. Furthermore, a systematic review on its development in China, is detailed in 6 stages. However, while its development in China since 2005 has been most profound, improvements are still needed in treatment concepts, instruments, treatment processes, attention to high-risk populations and cooperation with other dental/medical disciplines. Future projections based on present standards of care are also presented.

Influence of the lateral pterygoid muscle on traumatic temporomandibular joint bony ankylosis.

BACKGROUND: The pathogenesis of traumatic TMJ ankylosis remains unclear. This study aimed to verify the role of the lateral pterygoid muscle in the pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis. METHODS: Eight 6-month-old male sheep were used in this study. Bilateral TMJ osteotomies were performed to induce sagittal fractures of the mandibular condyle. The lateral one-fourth segment of the disc was removed to establish a model of TMJ bony ankylosis. Subsequently, the function of the left and right lateral pterygoid muscles was blocked (experimental group) or maintained (control group), respectively. At 12 weeks postoperatively, animals were sacrificed and TMJ complex samples were evaluated by gross observation, spiral computed tomography (CT), micro-CT, and histological examinations. RESULTS: Gross observation revealed bony ankylosis in the control TMJs and fibrous adhesions in the experimental TMJs. Spiral CT and micro-CT demonstrated that, compared to the experimental group, the control group showed calcified callus formation in the joint space and roughened articular surfaces after new bone formation, which protruded into the joint space. Maximum mediolateral and anteroposterior condylar diameters were significantly larger in the control group than in the experimental group. Micro-CT also showed that the primary growth orientation of new trabeculae was consistent with the direction of lateral pterygoid traction in the control group, but not in the experimental group. Histological examination showed fibro-osseous ankylosis in the control group, but not in the experimental group. CONCLUSIONS: The lateral pterygoid simulates the effects of distraction osteogenesis, which is an important factor in the pathogenesis of TMJ bony ankylosis during the healing of sagittal condylar fractures.

[Pain and prevention in extraction of the mandibular third molar].

OBJECTIVE: To study the post-operative pain-re1ated factors in lower third molar extraction, and to find an effective prevention program. METHODS: The first phase of the study was a clinical follow-up of 450 cases of lower third molar extraction. Factors associated with post-operative pain were analyzed, and difficulty assessment protocol of the tooth extinction was build. On this hasis, a pain-prevention clinical plan was constitute, and implemented in the second phase of 450 cases (selectively systemic or local medication). Treatment effects were observed. RESULTS: There were no significant differences between the two phase groups oh the distribution of ages, sex, difficulty of tooth extraction, operation time, and other related factors, means that they were statistically comparable. Tooth extraction difficulty and operation time were most important predictive factors for post-operative pain. Local infective factors (including caries) and women's menstrual cycle also account for late stage pain. Through targeted pre-operative medication or post-operative alveolar socket treatment, pain was significantly reduced or prevented. CONCLUSION: Reasonable peri-operative drug control basing on the difficulty assessment can provide a comprehensive and individualized control of pain after tooth extraction. Also, excessive or inappropriate using of drugs is largely avoided.

In vivo self-expanding engineering of bone.

In vivo bone formation and vascularization are interdependent process with complex regulatory mechanism. In vitro tissue engineering has meet great difficulty to copy all internal environment conditions, and the technology worked well only for relatively simple, thin tissues such as skin and cartilage that do not depend on a well-formed network of blood vessels to deliver food and oxygen. For more complex tissue of bone segments shot through with vessels, we hypothesize that an altered strategy might be effective: starting from in vitro tissue engineering for a thin sheet of primary product, then transferring to in vivo cultivation with a self-expanding procedure activated by interweaving metal springs of shape memory alloy (SMA). It is easy for thin sheet of engineering tissues to survive after implantation in vivo. Super-elasticity of SMA spring can gradually expand and re-shape the engineering product. More important, the continuous mechano-transduction effect can activate internal environment as a bioreactor for bone regeneration and vascularization. Our hypothesis integrates the existing knowledge and technologies, and could be a hopeful strategy for more convenient and safe use of bone engineering in clinics.

Transport distraction osteogenesis using nitinol spring: an exploration in canine mandible.

Some experiments in rabbits have presented the potential feasibility of using shape memory alloy spring for continuous distraction osteogenesis. To confirm the effectiveness of such method, we established canine models for the exploratory experiments of transport distraction osteogenesis using nitinol springs. Simple devices, including an internal 60-mm long sinusoid-shaped nitinol springs were used in the study. All dogs needed only one operation. In the operation, osteotomy was performed to create a 40-mm unilateral segmental mandibular body defect and a tooth-bearing transport bone disc. After reconstructive fixation of the remnant mandible, the spring was constricted and anchored across the distraction gap to activate transport distraction immediately. At the second experimental stage, an ePTFE sheet was further fixed to protect the defect and distraction gap before closing the incision. Control dogs underwent the same operation except for anchoring of the spring to examine the spontaneous bone regeneration. Automatic bone transportation, as a gradual slowdown process, was observed under the effect of the spring. The transport disc could get to the opposite side of the defect, or stopped halfway when ePTFE sheet intervened. Mandibular reconstruction was achieved in all these dogs and better in dogs with sheet protection. No integrated bone mass was found in the defect of control dogs. The study further proves that continuous distraction osteogenesis using nitinol springs is a practical technique, although the devices need more improvement for better control of the process of distraction and the quality of regenerated bone.

[Bone mineral density and biomechanical characters of the augmented alveolar ridge by distraction osteogenesis using Ti-Ni shape memory alloy distractor].

OBJECTIVE: To evaluate the quality of the alveolar ridge augmented by Ti-Ni shape memory alloy (Ti-Ni SMA) distractor. METHODS: All of the mandibular premolars and the first molars were extracted from 12 adult mongrel canines. One month later, box-shaped osteotomy was carried out in the left mandibles and Ti-Ni SMA distractors were imbedded. The right sides served as blank control. The canines were killed 3 or 6 months later and specimens were taken from corresponding area of the experiment sides and the control. Bone mineral density and biomechanical function were measured. RESULTS: Bone mineral density, ultimate compressive strength and Young's Modules of the augmented ridge were lower than the blank control three months after distraction. But the indexes increased and showed no significant difference with the control six months after distraction. CONCLUSIONS: The canines mandibular posterior alveolar ridge could be augmented by distraction osteogenesis using Ti-Ni SMA distractor, and the new bone is strong enough for implant placement.

[Segmental mandibular reconstruction by elasticity distraction osteogenesis associated with guided bone regeneration].

OBJECTIVE: To accelerate distraction osteogenesis by utilizing guided bone regeneration technique, and to improve the automatic process of canine segmental mandibular reconstruction by elasticity distraction osteogenesis using shape memory metal alloy distractor. METHODS: Adult hybrid canines were used. Osteotomy was performed to remove a bone segment of 2.5-4.0 cm in one side of the mandible. Mandibular fixation devices and shape memory metal alloy distractor were secured according to the principles of bi-focal distraction technique. A piece of ePTFE membrane was sutured to cover the buccal side of bone defect and osteotomy gap of transport disc, where the periosteum was peeled for exposing mandible in operation. Then the incisions were totally closed. The canines were sacrificed 3 months later to harvest the mandibles for morphological observation and measurement of bone density and intensity. RESULTS: The shape memory metal alloy distractor performed distraction osteogenesis automatically and reconstructed the mandibles with bone defect. A regenerated bone segment of 1.5-2.0 cm was formed in the compression region between transport disc and contralateral mandibular end. The new bone in both of distraction and compression regions had similar height and thickness with normal mandible. Moreover the new bone density and intensity were rather satisfied. CONCLUSIONS: Membrane guided bone regeneration can avoid bone synthesis commonly caused by cicatrization of soft tissue in the bone defect, and accelerate ossification and maturation of new generated bone.

[Design and application of internal devices for automatic elasticity distraction osteogenesis].

OBJECTIVE: To improve the design of the devices used for autoatic elasticity distraction osteogenesis, and to preliminarily testify their feasibility for clinical application. METHODS: The internal automatic distraction devices were constructed by three parts, including sinusoid shape memory alloy distractor, reconstructive plate and mini-plate. The animal model of trifocal bone transport reconstruction of canine mandibular mentis was duplicated, in which a 6 cm mandibular mentis segment was removed and the transport disc was created by osteotomy in both ends of the mandibular defect. The plates were used for internal fixation and shape reconstruction of the mandible. They also served as transport distraction guidance for the elasticity distractor. RESULTS: The new devices could complete bone transport as expected. Regenerated bone segments were formed in two months and both sides of the mandibular body were lengthened. Because of the narrow angle and obstruction from the thick soft tissues in the mentis area, the ultimate symphysis mentalis was not reconstructed. CONCLUSION: The design of the internal elasticity distraction devices showed potential feasibility for clinical practice. But further studies are still needed for better control of the strength and balance of distraction forces.

[Effects of different TiNi-SMA distractor on the height of alveolar ridge augmentation].

OBJECTIVE: To discuss the effects of titanium nickel shape memory alloy (TiNi-SMA) distractor with different stretching force and different distance between two fixed ends on the height of alveolar ridge augmentation. METHODS: The mini distractors were all made of TiNi-SMA wire. The maximum stretching force and the distance between two fixed ends according to different distractors (A, B and C) were 20 mm, 700 g; 15 mm, 1000 g; 20 mm, 1000 g. 15 adult mongrel canines were divided into three groups randomly and extracted the mandibular premolars and first molar. One month later, box-shaped osteotomies of the alveolar bone were carried out in the left mandible and the TiNi-SMA distractors were buried. The bone height was measured and the radiographs were taken before and five weeks post operation continuously. RESULTS: One week post operation, the vertical ridge augmentation of group A, B and C averaged (7.55 +/- 1.02) mm, (4.97 +/- 0.34) mm, (8.54 +/- 0.82) mm and the height remained (7.20 +/- 1.05) mm, (4.93 +/- 0.21) mm, (8.04 +/- 0.78) mm five weeks post operation. There was no statistic difference in the height of alveolar ridge augmentation between Group A and C, but Group B showed significant difference with the other two groups. In each group, the height did not changed significantly with the time. The radiographs showed obvious distraction gap post operation, and the new bone regenerated five weeks later. CONCLUSION: It suggests that in the scope of suitable stretching force, the height of alveolar ridge augmentation was determined by the size of TiNi-SMA distractor, that is to say, determined by the distance between the two fixed ends.

Effect of hepatoma H22 on lymphatic endothelium in vitro.

AIM: To determine the effect of metastatic hepatoma cells on lymphangioma-derived endothelium, and to establish in vitro model systems for assessing metastasis-related response of lymphatic endothelium. METHODS: Benign lymphangioma, induced by intraperitoneal injection of the incomplete Freund's adjuvant in BALB/c mice, was embedded in fibrin gel or digested and then cultured in the conditioned medium derived from hepatoma H22. Light and electron microscopy, and the transwell migration assay were used to determine the effect of H22 on tissue or cell culture. Expressions of Flt-4, c-Fos, proliferating cell nuclear antigen (PCNA), and inducible nitric oxide synthase (iNOS) in cultured cells, and content of nitric oxide in culture medium were also examined. RESULTS: The embedded lymphangioma pieces gave rise to array of capillaries, while separated cells from lymphangioma grew to a cobblestone-like monolayer. H22 activated growth and migration of the capillaries and cells, induced expressions of Flt-4, c-Fos, PCNA and iNOS in cultured cells, and significantly increased the content of NO in the culture medium. CONCLUSION: Lymphangioma-derived cells keep the differentiated phenotypes of lymphatic endothelium, and the models established in this study are feasible for in vitro study of metastasis-related response of lymphatic endothelium.

Rapid lengthening of rabbit mandibular ramus by using nitinol spring: a preliminary study.

Nitinol is well known for its shape memory and superelasticity, which means it can return to its original shape from large deflections and produce moderate forces in the process. Based on these characteristics, the authors attempted to use an internal Nitinol spring for automatic lengthening of mandibular ramus. Twenty adult white rabbits underwent transverse osteotomy in unilateral mandibular ramus to remove a 15.0 mm condylar segment and L-osteotomy in remnant ramus to create a vascularized transport disc. The S-shaped Nitinol spring, with two ends bent as perpendicular underprops, was constricted and secured across the transverse gap of L osteotomy by the underprops. Six animals were killed 6 days after operation for observation of bone transport rate. Other surviving rabbits were killed 8 weeks later for morphologic and histologic examination. Mechanical testing revealed moderate output of tensile elasticity by constricted spring on shape recovery in 37 degrees C. Rapid lengthening of mandibular ramus, more than 9.0 mm in 5 to 6 days, and new bone formation in 8 weeks were found. The radiograph and histologic appearance of regenerated bone was similar to those seen with traditional distraction osteogenesis. This preliminary study demonstrates the possibility of spring-mediated rapid mandibular lengthening across an osteotomy. However, the method needs additional scientific investigation for its clinical feasibility.

[Le Fort III osteotomy and medium position distraction for mid-facial hypoplasia].

OBJECTIVE: To probe the possibility of distraction osteogenesis for correction of mid-facial hypplasia using a new technique. METHODS: The distraction system of mid-facial skeleton consisted of a face-bow, the elastic loops and a device that hitched to bone holes made in the aperture rim. Flllowing Le Fort III osteotomy, a bone hole was drilled at each side of the external-inferior rim of the aperture by a dental bur. The traction device was hitched to the holes through the nostrils. Distraction began three days postoperatively, with the force adjusted dependently upon the rate of progress. When the skeleton reached to the planed position, distraction was retained with a minor force for 8 weeks. Three adults with mid-facial hypoplasia underwent this treatment. RESULTS: The mid-facial skeleton showed a balanced advancement. The patients' facial contour and occlusal relationship recovered completely. CONCLUSIONS: Patients with severe mid-facial hypoplasia could be corrected ideally by the new technique, with balanced advancement of mid-facial skeleton, minor trauma. The design of distraction system was reasonable. The manipulation of the procedure was easy.

[Reconstruction of segmental mandibular defect of canine using titanium-nickel distractor].

OBJECTIVE: To establish a continuous and automatic distraction osteogenesis technique in reconstruction of segmental mandibular defect by using embedded titanium-nickel alloy distractor with characteristics of shape-memory and super-elasticity. METHODS: Adult hybrid canines were used as the animal model. Segmental defects of 1-3 cm in the body of mandible were created by surgical osteotomy. Bi-focal distraction osteogenesis was applied using embedded titanium-nickel distractor designed by the authors. The canines were sacrificed 3 months after the operation and the mandibles were harvested to examine the results of bone regeneration. RESULTS: The histocompatibility of titanium-nickel distractors was good. Distraction osteogenesis was completed automatically and the defects were elementarily restored. Radiological and histological examination showed well bone regeneration in distraction area. CONCLUSIONS: Distraction osteogenesis using embedded self-loading titanium-nickel distractor could be a hopeful and useful technique. It might help to solve the problems of functional mandibular reconstruction in the near future.

[Induction of lymphangiogenesis by mouse ascites hepatoma cell H22 in vitro].

OBJECTIVE: To construct lymphangiogenesis model of Balb/c mouse in vitro to observe the impact of mouse ascites hepatoma cell H22 on the lymphangiogenesis and lymphatic endothelial proliferation. METHODS: Intraperitoneal benign lymphangioma induced by incomplete Freund's adjuvant in Balb/c mouse was harvested and embedded in fibrin gel to culture in vitro with conditioned medium (CM) of H22 cell. The gels, observed by inverted microscope and transmission electron microscope, were then digested to separate the cells. The expression of Flt-4, c-fos and iNOS in the cell and the content of NO in medium were studied by immunohistochemical and histochemical method. RESULTS: Lymphatic capillary generating from lymphangioma specimen in the gels was observed by inverted microscope and transmission electron microscope. H22 CM was observed to enhance growth of the vessels, induce expressions of Flt-4, c-fos and iNOS in the separated cells and increase content of NO in the medium. CONCLUSION: The model is convenient for in vitro study of lymphangiogenesis. H22 cell can accelerate lymphangiogenesis, which warrants further study for the understanding of the role of lymphangiogenesis in metastasis.