Large-Scale, Mechanically Robust, Solvent-Resistant, and Antioxidant MXene-Based Composites for Reliable Long-Term Infrared Stealth

MXene-based thermal camouflage materials have gained increasing attention due to their low emissivity, however, the poor anti-oxidation restricts their potential applications under complex environments. Various modification methods and strategies, e.g., the addition of antioxidant molecules and fillers have been developed to overcome this, but the realization of long-term, reliable thermal camouflage using MXene network (coating) with excellent comprehensive performance remains a great challenge. Here, a MXene-based hybrid network comodified with hyaluronic acid (HA) and hyperbranched polysiloxane (HSi) molecules is designed and fabricated. Notably, the presence of appreciated HA molecules restricts the oxidation of MXene sheets without altering infrared stealth performance, superior to other water-soluble polymers; while the HSi molecules can act as efficient cross-linking agents to generate strong interactions between MXene sheets and HA molecules. The optimized MXene/HA/HSi composites exhibit excellent mechanical flexibility (folded into crane structure), good water/solvent resistance, and long-term stable thermal camouflage capability (with low infrared emissivity of ≈0.29). The long-term thermal camouflage reliability (≈8 months) under various outdoor weathers and the scalable coating capability of the MXene-coated textile enable them to disguise the IR signal of various targets in complex environments, indicating the great promise of achieved material for thermal camouflage, IR stealth, and counter surveillance.

Thermoelectrics and thermocells for fire warning applications

Historically, fire disasters have killed numerous human lives, and caused tremendous property loss. Fire warning systems play a vital role in predicting fire risks, and are strongly desired to effectively prevent the disaster occurrence and significantly reduce the loss. Among the developed fire warning systems, thermoelectrics (TEs) and thermocells (TECs)-based fire warning materials are extremely important and indispensable in future research, owing to their unique capability of direct conversion between heat and electricity. Here, we present this review of the recent progress of TEs and TECs in fire warning field. Firstly, a brief introduction of existing fire warning systems is provided, including the mechanisms and features of various types. Then, the mechanisms of electronic TE (eTE), ionic TE (iTE) and TEC are elucidated. Next, the basic principles for the material preparation and device fabrication are discussed in their dimension sequence. Subsequently, some important advances or examples of TE fire warnings are highlighted in details. Finally, the challenges and prospects are outlooked.

Intelligent cyclic fire warning sensor based on hybrid PBO nanofiber and montmorillonite nanocomposite papers decorated with phenyltriethoxysilane

An abundance of early warning graphene-based nano-materials and sensors have been developed to avoid and prevent the critical fire risk of combustible materials. However, there are still some limitations that should be addressed, such as the black color, high-cost and single fire warning response of graphene-based fire warning materials. Herein, we report an unexpected montmorillonite (MMT)-based intelligent fire warning materials that have excellent fire cyclic warning performance and reliable flame retardancy. Combining phenyltriethoxysilane (PTES) molecules, poly(p-phenylene benzobisoxazole) nanofiber (PBONF), and layers of MMT to form a silane crosslinked 3D nanonetwork system, the homologous PTES decorated MMT-PBONF nanocomposites are designed and fabricated via a sol-gel process and low temperature self-assembly method. The optimized nanocomposite paper shows good mechanical flexibility (good recovery after kneading or bending process), high tensile strength of ∼81 MPa and good water resistance. Furthermore, the nanocomposite paper exhibits high-temperature flame resistance (almost unchanged structure and size after 120 s combustion), sensitive flame alarm response (∼0.3 s response once exposure onto a flame), cyclic fire warning performance (>40 cycles), and adaptability to complex fire situations (several fire attack and evacuation scenarios), showing promising applications for monitoring the critical fire risk of combustible materials. Therefore, this work paves a rational way for design and fabrication of MMT-based smart fire warning materials that combine excellent flame shielding and sensitive fire alarm functions.

Biomimetic, Mechanically Strong Supramolecular Nanosystem Enabling Solvent Resistance, Reliable Fire Protection and Ultralong Fire Warning

A graphene oxide (GO)-based smart fire alarm sensor (FAS) has gained rapidly increasing research interest in fire safety fields recently. However, it still remains a huge challenge to obtain desirable GO-based FAS materials with integrated performances of mechanical flexibility/robustness, harsh environment-tolerance, high-temperature resistance, and reliable fire warning and protection. In this work, based on bionic design, the supermolecule melamine diborate (M·2B) was combined with GO nanosheets to form supramolecular cross-linking nanosystems, and the corresponding GO-M·2B (GO/MB) hybrid papers with a nacre-like micro/nano structure were successfully fabricated via a gel-dry method. The optimized GO/MB paper exhibits enhanced mechanical properties, e.g., tensile strength and toughness up to ∼122 MPa and ∼1.72 MJ/m³, respectively, which is ∼3.5 and ∼6.6 times higher than those of the GO paper. Besides, it also shows excellent structural stability even under acid/alkaline solution immersion and water bath ultrasonication conditions. Furthermore, due to the presence of promoting reduction effect and atom doping reactions in GO network, the resulting GO/MB network displays exceptional high-temperature resistance, sensitive fire alarm response (∼0.72 s), and ultralong alarming time (>1200 s), showing promising fire safety and protection application prospects as desirable FAS and fire shielding material with excellent comprehensive performances. Therefore, this work provides inspiration for the design and fabrication of high-performance GO-based smart materials that combine fire shielding and alarm functions.

Fire Intumescent, High-Temperature Resistant, Mechanically Flexible Graphene Oxide Network for Exceptional Fire Shielding and Ultra-Fast Fire Warning

Smart fire alarm sensor (FAS) materials with mechanically robust, excellent flame retardancy as well as ultra-sensitive temperature-responsive capability are highly attractive platforms for fire safety application. However, most reported FAS materials can hardly provide sensitive, continuous and reliable alarm signal output due to their undesirable temperature-responsive, flame-resistant and mechanical performances. To overcome these hurdles, herein, we utilize the multi-amino molecule, named HCPA, that can serve as triple-roles including cross-linker, fire retardant and reducing agent for decorating graphene oxide (GO) sheets and obtaining the GO/HCPA hybrid networks. Benefiting from the formation of multi-interactions in hybrid network, the optimized GO/HCPA network exhibits significant increment in mechanical strength, e.g., tensile strength and toughness increase of ~ 2.3 and ~ 5.7 times, respectively, compared to the control one. More importantly, based on P and N doping and promoting thermal reduction effect on GO network, the excellent flame retardancy (withstanding ~ 1200 °C flame attack), ultra-fast fire alarm response time (~ 0.6 s) and ultra-long alarming period (> 600 s) are obtained, representing the best comprehensive performance of GO-based FAS counterparts. Furthermore, based on GO/HCPA network, the fireproof coating is constructed and applied in polymer foam and exhibited exceptional fire shielding performance. This work provides a new idea for designing and fabricating desirable FAS materials and fireproof coatings.

Efficient Flame Detection and Early Warning Sensors on Combustible Materials Using Hierarchical Graphene Oxide/Silicone Coatings

Design and development of smart sensors for rapid flame detection in postcombustion and early fire warning in precombustion situations are critically needed to improve the fire safety of combustible materials in many applications. Herein, we describe the fabrication of hierarchical coatings created by assembling a multilayered graphene oxide (GO)/silicone structure onto different combustible substrate materials. The resulting coatings exhibit distinct temperature-responsive electrical resistance change as efficient early warning sensors for detecting abnormal high environmental temperature, thus enabling fire prevention below the ignition temperature of combustible materials. After encountering a flame attack, we demonstrate extremely rapid flame detection response in 2-3 s and excellent flame self-extinguishing retardancy for the multilayered GO/silicone structure that can be synergistically transformed to a multiscale graphene/nanosilica protection layer. The hierarchical coatings developed are promising for fire prevention and protection applications in various critical fire risk and related perilous circumstances.

[A brief history of Beijing Shijitan(Century Altar) Hospital]

Founded in 1914, the Jing-Han Railway Hospital has undergone through four different stages during its 100 years' transition, viz., from 1914 to 1949, from 1949 to 1979, from 1980 to 2003 and from 2004 to the present, with its title changing from Peking-Hankou Railway Hospital, Beijing Health Care Station, Peiping Railway Hospital, Beijing Railway General Hospital and today's Beijing Shijitan Hospital. As a railway hospital, in addition to offering services to Chinese railway health, it has also participated in many public welfare activities, such as major disaster rescues, important domestic medical services, the international medical assistance, hospitals' counterpart support, Lifeline Express and so on.In a sense, the establishment and development of the hospital are connected with Beijing Railway Health Services and is not only closely related with China's railway healthcare, but also to modern social transformation and changes.

A novel semiconductor compatible path for nano-graphene synthesis using CBr4 precursor and Ga catalyst

We propose a novel semiconductor compatible path for nano-graphene synthesis using precursors containing C-Br bonding and liquid catalyst. The unique combination of CBr4 as precursor and Ga as catalyst leads to efficient C precipitation at a synthesis temperature of 200 °C or lower. The non-wetting nature of liquid Ga on tested substrates limits nano-scale graphene to form on Ga droplets and substrate surfaces at low synthesis temperatures of T ≤ 450 °C and at droplet/substrate interfaces by C diffusion via droplet edges when T ≥ 400 °C. Good quality interface nano-graphene is demonstrated and the quality can be further improved by optimization of synthesis conditions and proper selection of substrate type and orientation. The proposed method provides a scalable and transfer-free route to synthesize graphene/semiconductor heterostructures, graphene quantum dots as well as patterned graphene nano-structures at a medium temperature range of 400-700 °C suitable for most important elementary and compound semiconductors.

Peri-implant conditions and their relationship with periodontal conditions in Chinese patients: a cross-sectional study

OBJECTIVES

To analyze the relationships between peri-implant conditions and periodontal conditions in Chinese patients with dental implants in place for at least 1 year.

MATERIAL AND METHODS

Seventy-six patients (mean age, 41 ± 10 years; range, 21-69 years) who received placement of 120 dental implants (Straumann(®) ), (mean 1.6 implants per subject; range, 1-5 implants per subject) after a mean period of 25 months (range, 12-66 months) responded to recall. Clinical examinations were performed around the implants and natural teeth. Periapical radiographs were taken by the long cone technique for implants, and radiographic bone level (BL) was measured. Comparisons of the peri-implant conditions were performed between the patients with different periodontal conditions by t-test and chi-square test. The relative risk of periodontal condition as a risk factor for peri-implant conditions was analyzed by logistic regression.

RESULTS

Subjects who presented with ≥5% sites with probing depth (PD) ≥ 4 mm and ≥30% sites with bleeding on probing (BoP) in the dentition showed significantly poorer peri-implant conditions (58% vs. 18% subjects who had maximum modified gingival index (mGI) 2 or 3, P = 0.003; 94% vs. 62% subjects who had maximum PD ≥ 4 mm, P = 0.008; 100% vs. 79% subjects who had BoP, P = 0.044; mean PD 3.36 ± 0.66 vs. 2.75 ± 0.66 mm, P = 0.002; and sites% with BoP 68 ± 23% vs. 36 ± 31%, P < 0.001), as compared with those who had <5% sites with PD ≥ 4 mm and <30% sites with BoP on the remaining teeth. The relative risk for subjects with the more severe and extensive periodontal conditions compared to those with better periodontal conditions to have PD ≥ 5 mm with BoP at peri-implant sites was 23.3 (P = 0.003, 95% CI, 2.8-192.3.

CONCLUSIONS

The peri-implant conditions were significantly related to the periodontal conditions around the remaining natural teeth, which implies that control of periodontal disease is essential for successful implant treatment.

Plasma frequency and dielectric function dependence on doping and temperature for p-type indium phosphide epitaxial films

The optical properties of p-type InP epitaxial films with different doping concentrations are investigated by infrared absorption measurements accompanied by reflection and transmission spectra taken from 25 to 300 K. A complete dielectric function (DF) model, including intervalence band (IVB) transitions, free-carrier and lattice absorption, is used to determine the optical constants with improved accuracy in the spectral range from 2 to 35 μm. The IVB transitions by free holes among the split-off, light-hole, and heavy-hole bands are studied using the DF model under the parabolic-band approximation. A good understanding of IVB transitions and the absorption coefficient is useful for designing high operating temperature and high detectivity infrared detectors and other optoelectronic devices. In addition, refractive index values reported here are useful for optoelectronic device designing, such as implementing p-InP waveguides in semiconductor quantum cascade lasers. The temperature dependence of hole effective mass and plasma frequency is also reported.

Relationship between vitamin D receptor gene polymorphism and periodontitis

Recent studies have shown that vitamin D receptor (VDR) gene polymorphism had regulatory effects on bone mineral density (BMD) and bone turnover. The VDR gene has also been indicated as a candidate gene for the susceptibility of osteoporosis. However, it is unclear whether VDR genotypes could be associated with alveolar bone loss of patients with periodontitis, or whether vitamin D receptor gene could be a candidate gene for susceptibility to periodontitis. The purpose of this study was to answer these two questions.

METHODS

Twenty-four cases of adult periodontitis (AP), 37 cases of early onset periodontitis (EOP) and 39 healthy controls were recruited for the study. Individual samples of venous blood and DNA were obtained from each subject. Genotypes of the TaqI VDR gene were determined by PCR and TaqI restriction endonuclease digestion.

RESULTS

One out of 24 AP patients, nine out of 37 EOP patients and two out of 39 healthy controls were detected with Tt genotype, while the rest had the TT genotype. The detected frequency of Tt genotype was significantly higher in EOP patients (24.3%) than in AP patients (4.2%) and healthy controls (5.1%). The frequency of t allele was also significantly higher in EOP patients. There was no statistical difference in the distribution of TaqI VDR genotypes between AP patients and healthy controls. The study suggests that Tt genotype might be a risk indicator for the susceptibility to EOP. Carriage of the allele (t) of the TaqI VDR gene may increase the risk of developing EOP.

Polymorphonuclear neutrophils and their mediators in gingival tissues from generalized aggressive periodontitis

BACKGROUND

Impaired polymorphonuclear neutrophil (PMN) functions were generally considered to be related to the onset of generalized aggressive periodontitis (GAgP). However, some research has indicated that the hyperreactivity of PMN seems to be involved in the inflammatory response of GAgP. The present study's main purpose was to provide more evidence about the role of PMN in the pathogenesis of GAgP by surveying PMN infiltration in gingiva and its relationship with the expression of their mediators including intercellular adhesion molecule-1 (ICAM-1), interleukin-8 (IL-8), interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha). The inflammatory response in GAgP was also compared with that in adult periodontitis (AP) and periodontally healthy subjects. Since these PMN mediators were reported to be produced mainly by macrophages, the association between the expression of these PMN mediators and the distribution of macrophages was also investigated.

METHODS

A total of 25 gingival specimens were obtained from 10 GAgP patients, 10 AP patients, and 5 periodontally healthy subjects. Serial sections were obtained from each specimen, and the following techniques were adopted to investigate the distribution and interrelation of different cells and cytokines. Infiltration of PMN was observed by using hematoxylin and eosin staining. Distribution of the macrophages, identified as CD68+, was shown by using immunohistochemistry. Immunohistochemistry and in situ hybridization were used to detect the expression of ICAM-1, IL-8, IL-1beta, and TNF-alpha in gingival tissues. These techniques were performed in serial sections from each individual specimen.

RESULTS

Large numbers of infiltrating PMNs were observed in gingiva from GAgP. In gingiva from both GAgP and AP, the strongest protein and mRNA expression of IL-8, ICAM-1, IL-1beta, and TNF-alpha were located in pocket epithelium and adjacent connective tissue with large numbers of infiltrating PMNs. In tissues without abundant PMN infiltration, the appearance of positive cells expressing IL-8, ICAM-1, IL-1beta, and TNF-alpha was scattered. CD68+ was distributed sparsely in connective tissue and was hardly seen in pocket epithelium with large numbers of PMN infiltration. The degree of leukocyte infiltration and connective tissue destruction in gingiva from GAgP patients was not distinctly different from that in gingiva from AP. The gingival specimens with heavy PMN infiltration from both GAgP and AP patients presented strong expressions of IL-1beta and TNF-alpha; showed more extensive inflammatory cell infiltration; had severe connective tissue destruction; and presented severe elongation and ulceration of pocket epithelium. In gingiva from healthy subjects, inflammation was minor with visually no PMN, CD68+, or the positive cells of IL-8, ICAM-1, IL-1beta and TNF-alpha expression.

CONCLUSIONS

Enhanced accumulation of PMN, which is associated with the upregulation of IL-8, ICAM-1, IL-1beta, and TNF-alpha expression, relates to the severity and activity of GAgP. In addition to macrophages, PMN and/or epithelial cells might also be important sources of IL-8, IL-1beta, and TNF-alpha production in gingiva.

Photolysis of pesticides: influence of epicuticular waxes from Persica laevis DC on the photodegradation in the solid phase of aminocarb, methiocarb and fenthion

Pesticides with N,N-dimethyl and thiomethyl moieties (aminocarb, methiocarb and fenthion) were irradiated under artificial light (lambda > 290 nm) in an amorphous wax phase from Persica laevis DC. The effect of the presence of the wax on the photolysis rate differed in the three pesticides, increasing it in aminocarb, having little effect in methiocarb and slowing it down in fenthion. The presence of the wax affected the qualitative photodegradation behaviour of all the pesticides. The data obtained were compared with those for pirimicarb, which had been studied earlier.

Phenolic compounds in virgin olive oil. 2. Reappraisal of the extraction, HPLC separation, and quantification procedures

The extraction procedures (solid/liquid SPE and liquid/liquid LLE) and HPLC separation and quantification methods of polyphenolic compounds have been checked in virgin olive oils in order to explain the differences in content reported in the literature. The work has been carried out on oils prepared from one cultivar and produced under the same protocol. The extraction methods are practically equivalent, but the SPE technique is more favorable because it is faster and simpler. It has been proved that the chromatographic features and the method of chemical expression of the concentrations may greatly affect the final values. Thus, under the same analytical method, the total concentration values of polyphenols of the same oil show variations from 18% to 80%, according to the formality of expression as gallic acid, caffeic acid, or tyrosol equivalents. The role of the nature and spectrophotometric features of the phenols and of the internal standard is also discussed, and it was found to be an important source of reported variation. A gradient separation with an eluent mixture acetonitrile-sulfuric acid (0.1 mol/L), detection at 225 nm, and quantitative calculation of polyphenolic compounds in oils (expressed as tyrosol equivalents, THY(eq)) is proposed.

Attachment loss in rural Chinese children over a 3-year period

OBJECTIVES

The periodontal condition of 84 children (9-14 years old, 38 males and 46 females) in a rural area of China was monitored over a 3-year period in order to determine the clinical parameters that act as risk factors for attachment loss.

METHODS

Plaque and calculus accumulation (PSS and CI), modified gingival index (MGI), pocket depth (PD) and attachment level (AL) of two quadrants of each child were examined in 1993 and 1996. Following calculation of the mean of each of these parameters and statistical analysis of the change in each of the clinical parameters over the 3-year period, the relationship between attachment loss and clinical parameters was analyzed using multiple regression analysis.

RESULTS

At the beginning of this study, the mean values for males and females were 3.66 and 3.58 for PSS, 1.22 and 1.17 for MGI, 1.07 and 0.90 for CI, 2.21 and 2.22 for PD, and both 0.02 for AL respectively. No significant difference between males and females was observed. After 3 years, all except mean PSS had increased significantly. Multiple regression analysis indicated that AL correlated only to age (P<0.01). In 1993, although the AL was > or =1 mm for at least one site in 21 children, none had an AL> or =3 mm. In 1996, the number of children with an AL> or =1 mm had increased to 63, and nine of these children exhibited 3 mm AL (one to six sites per child). No other significant differences were observed between the clinical data of these nine children and those of the other children.

CONCLUSION

Although attachment loss tended to increase with age, no clinical parameters correlated with attachment loss in children.

Detection of small lesions in alveolar bone by digital subtraction radiography

OBJECTIVE

To evaluate the effectiveness of digital subtraction radiography (DSR) system for diagnosis of small artificial alveolar bone lesions.

METHODS

Seventy-two 0.2-0.9 mm3 lesions were produced in premolar and molar areas of dry human mandibles. Reference and subsequent radiographs were taken before and after lesions were made. The small lesions were detected by conventional radiography and DSR respectively.

RESULTS

For 0.2-0.5 mm3 lesions, detection by both DSR and conventional methods was less than 50%. For 0.7 mm3 lesions, the detection by DSR and conventional methods was 57.5% and 38.7%, respectively (P < 0.01). For 0.9 mm3 lesions, the accuracy of the detection by DSR and conventional methods was 89.3% and 57.3% (P < 0.01).

CONCLUSION

The detectability of small alveolar bone lesions by DSR was superior to that of the conventional method.

Genetic analysis of dental traits in 82 pairs of female-female twins

OBJECTIVE

To study systematically the heritability of dental traits.

METHODS

Eighty-two pairs of female-female twins from 6 to 12 years old were collected. Twin zygosity diagnosis was made by DNA fingerprinting. The study was composed of questionnaires, oral examinations, model measurements, and panoramic radiographs. The same analytic method was used for each of the dental traits and comparison of their heritability was made.

RESULTS AND CONCLUSIONS

According to the significance of difference and the level of heritability, the dental traits were divided into four types: strong, median, weak, and weaker heritability. The number of third molars present, tooth size, arch size, and upper lateral incisor malformation were under strong genetic influence; hypodontia indicated a median heritability; a weak heritability was seen in tooth eruption and caries, and a weaker heritability was found in occlusal traits. The division made it easy to learn the genetic characteristics of dental traits systematically and supplemented the theory of dental genetics.

Existence of IL-8 degrading protease and anti-IL-8 immunoglobulin G in gingival crevicular fluid

OBJECTIVE

The aim of this study is to identify the nature of the IL-8 inhibitor(s) in gingival crevicular fluid (GCF).

METHODS

Part 1: Fourteen GCF samples were collected from 13 adult periodontitis (AP) patients, and 9 samples were taken from 8 healthy subjects. Each GCF sample was divided into two aliquots. A serine protease-specific inhibitor, PMSF, was added to one aliquot, and PBS was added to the other aliquot as control. ELISA was used to measure IL-8 level in the samples. Part 2: Forty-one GCF samples were collected from 15 AP patients and indirect ELISA was performed to detect the anti-IL-8 IgG antibody.

RESULTS

Part 1: IL-8 level in the PMSF samples was significantly greater than that in the control group (3.01 +/- 5.79 mg/L vs 0.05 +/- 0.15 mg/L, respectively P < .001). Part 2: The mean value of anti-IL-8 IgG in GCF was greater than that of negative control + 3 x SD.

CONCLUSIONS

A serine protease that can "cleave" IL-8 exists in GCF. Gingival crevicular fluid from AP sites contains an autoantibody against IL-8.

Herbal medicine for periodontal diseases

Traditional Chinese Medicine (TCM) is a treasure-house which has shown miraculous clinical effects. It has aroused tremendous interests in elucidating its mechanisms both in China and abroad. This paper presents a review of published articles on the effects and mechanisms of herbal medicine on periodontal disease. Specifically, two modifications of an ancient compound prescription were serially studied, Guchiwan (Tooth-firming pills) and Guchigao (Tooth-firming extract). Some in vitro studies have shown suppressive effects of various herbal extracts on bone resorption by isolated osteoclasts. TCM should be intensively studied for their possible use in periodontics.

[Pulsed ND:YAG laser irradiation and 2% NaF treatment in caries-like lesion formation in enamel:an in vitro study]

The purpose of this in vitro study was to determine the combined effects of ND:YAG laser irradiation and 2% NaF on caries-like lesion formation in human enamel.There were four groups:(1)control;(2)Nd:YAG laser only;(3)2%NaF only;(4)Nd:YAG laser before 2% NaF.The result show the lesion body depths were significant differences between the control group and all treatment group,and between Nd:YAG laser before 2% NaF group and both Nd:YAG laser group and 2% NaF group(P<0.05).The surface zone depths between Nd:YAG laser before 2% NaF group and both 2% NaF group and both 2% NaF group and control group were also significantly different(P<0.05).

[Longitudinal study on periodontal disease activity in treated periodontitis patients]

The aim of this study was to estimate the incidence of periodontal disease activity (PDA) in treated periodontitis patients in a longitudinal survey. Seven periodontitis patients with 170 teeth (970 sites) participated in this 6 to 12 month study. After initial therapy, the clinical parameters including attachment level (AL) were recorded as the baseline data and then repeated every two months. Occlusal stents were used for each patient to assure the accuracy and reproductivity of the attachment level measurements. Detection of > or = 2 mm of new AL between two consecutive visits was required to designate a site as PDA. During the study period, 21 sites out of 970 sites showed PDA. For better accuracy, we calculated the yearly PDA rate based on the 6-month data because not all the seven patients finished the 12-month observation. The estimated PDA rate per year was 2.8%. Data also showed that maxillary bicuspids and molars on both jaws were more susceptible to PDA. Interproximal sites and sites with > or = 6 mm pockets before treatment showed significantly greater PDA rate than buccal (lingual) sites and sites with < or = 4 mm initial pocket depth. Our data supports the tooth specific and site specific concept in periodontal disease.

[Evaluation of relation between signs of trauma from occlusion and severity of periodontitis]

The aim of the present study was to evaluate the various occlusal interferences, signs of trauma from occlusion and their relations to severity of periodontitis. 32 cases of moderate to advanced adult periodontitis patients participated in the study with a mean age of 37.6 years. All subjects received a complete periodontal examination and occlusal analysis. The results indicated that teeth with various occlusal interferences did not exhibit any greater severity of periodontitis than those without interferences. However, widened periodontal ligament space (PDLS) was frequently seen in teeth with occlusal interference. Two combined criteria were initially suggested to identify the occlusal trauma in clinic. The first criterion included presence of functional tooth mobility plus radiographically widened PDLS. The second, presence of significant tooth wear plus radiographically thickened lamina dura. The results showed that teeth with the first criteria had deeper probing depth, more clinical attachment loss and less alveolar bone support than teeth without these findings. However, teeth with the second criteria had less attachment loss and more bone support than teeth from control group. It was suggested that both of the combined criteria provide better reliability in determination of established occlusal trauma as well as evaluation of adaptive capacity of periodontal structure to increased biting force. The regression analysis demonstrated that given equal clinical attachment levels and similar inflammation, teeth with evidences of functional mobility and widened PDLS had less osseous support than teeth without these findings (P < 0.01). The difference became greater in line with the more loss of clinical attachment.

[Clinical evaluation of manual and ultrasonic subgingival scaling using image analysis]

The objective of this study was to compare the effect of hand and ultrasonic instrumentation in removing subgingival plaque and calculus.In experiment one,forty-eight teeth from patients were randomly assigned to be scaled with curettes or ultrasonic scaler.Probing depth,clinical attachment level and bleeding index were reexamined 2 months latter.The results demonstrated that no significant differences between the two mehtods.In experiment two,seventeen teeth from six patient were also randomly scaled manualty ultrasonic or uninstrumented as a control.All these teeth were extracted immediately after subgingival scaling.The proportion of tooth surfaces covered by residual plaque and calculus(relative to the total surface area of the side of the tooth)was analysed on each tooth using computerized graphic processing.The findings showed the proportional areas of residual plaque and calculus in teeth.But the hand scaled root surface were much smoother than those treated with ultrasonic scaler.

Clinical diagnosis of trauma from occlusion and its relation with severity of periodontitis

The purpose of the present study was to determine the reliability of several selected signs of trauma from occlusion and their relations with severity of periodontitis. 32 moderate to advanced chronic periodontitis patients participated in the study. All teeth present were evaluated for various abnormal occlusal contacts, signs of trauma from occlusion, and the severity of periodontitis. Standardized periapical radiographs were also taken for each tooth. The results demonstrated that: (1) no significant difference occurred in probing pocket depth (PD), clinical attachment loss (AL), or percentage of alveolar bone height (BH) between teeth with and without various abnormal occlusal contacts, i.e., premature contacts in centric relation occlusion, non-working contacts in lateral excursions, premature contacts of anterior teeth or posterior protrusive tooth contacts; (2) teeth with either significant mobility, functional mobility, or radiographically widened periodontal ligament space (PDLS) had deeper PD, more AL and lower BH than teeth without these signs, while teeth with pronounced wear or radiographically thickened lamina dura had less AL than teeth without these findings; (3) 2 combined indices, i.e., the trauma from occlusion index (TOI) and the adaptability index (AI), were proposed for the identification of occlusal trauma and the response of periodontium to excessive biting forces in heavy function, respectively; TOI-positive teeth exhibit deeper PD, more AL and less osseous support than TOI-negative teeth; however, AI-positive teeth had less AL and more osseous support than AI-negative teeth; (4) with identical attachment level, TOI-positive teeth had less osseous support than TOI-negative teeth while the magnitude of difference became greater with an increase of attachment loss.

[Relationship between serum antibody to Bacteroides gingivalis and clinical parameters in periodontitis patients]

Prevalence and proportion of black-pigmented Bacteroides species (BPB) in supragingival and subgingival plaque were determined in ten adult periodontitis patients. Serum antibody against Bacteroides gingivalis (Bg) of these patients were tested using ELISA. Clinical parameters (PI, GI, PD, AL) were collected prior to blood withdrawn. Results showed that BPB were detected in all patients. Mean serum anti-Bg IgG level was significantly greater in the patient group than that in healthy control group. Although the sample size was too small to show statistical difference, there was a trend showing the sera anti-Bg IgG level tended to be greater in accordance with the increase of disease severity and BPB%.

Comparison of plaque microflora between Chinese and Caucasian population groups

This investigation was designed to compare the predominant plaque micro-organisms from a Chinese group of patients exhibiting periodontitis with an age-, sex- and periodontal disease-matched Caucasian group of patients. In addition to race, the 2 population groups differed with respect to diet and oral hygiene habits, or effectiveness at removing plaque. Clinical measurements were determined along with an evaluation for micro-organisms in supragingival and subgingival plaque. Although the Chinese and Caucasian population groups were similar with respect to composition of micro-organisms in subgingival plaque, notable differences were observed in supragingival plaque. The Chinese group had higher mean proportions of spirochetes, motile rods. Fusobacterium spp. and dark-pigmented Bacteroides species, while the Caucasian group had higher mean proportions of cocci, total Actinomyces spp., A. viscosus and total Streptococcus spp. in supragingival plaque. The microbial differences observed in supragingival plaque may be explained at least in part, if not totally, by the higher plaque index scores of the Chinese versus Caucasian population groups.

[Crevicular fluid myeloperoxidase and periodontitis disease]

The volume and myeloperoxidase (MPO) activity of gingival crevicular fluid (GCF) collected with filter paper strips for 30 sec from the sulcus of healthy, gingivitis and periodontitis sites of Chinese subjects were measured. MPO/site and MPO/microliter GCF were both greater at gingivitis and periodontitis sites than healthy sites. Enzyme activity was similar at the 2 categories of diseased sites. Mean GCF volume and MPO activity of the samples were calculated for all sites with GI 0, 1, 2 and 0 + 1 irrespective of experimental group assignment. GCF volume MPO/site and MPO/microliter GCF all were greater at GI 2 than GI 0 or 0 + 1. These data indicate that increased GCF MPO previously observed at periodontitis sites is not specific to these sites. Rather, increased GCF MPO likely occurs when additional polymorphonuclear leukocytes enter the sulcus as a result of gingival inflammation. A second sample was obtained from 22 sites 4 weeks after the initial collection. These samples were collected for 5 rather than 30 sec. The GCF volume, MPO/site and MPO/microliter GCF each were greater in samples collected for 30 rather than 5 sec. Correlation coefficients showed that the amount of GCF and MPO activity of the fluid collected for 5 and 30 sec was dependent upon the site even though the samples were collected at different times.

Crevicular fluid myeloperoxidase at healthy, gingivitis and periodontitis sites

The volume and myeloperoxidase (MPO) activity of gingival crevicular fluid (GCF) collected with filter paper strips for 30 s from the sulcus of healthy, gingivitis and periodontitis sites of Chinese subjects were measured. MPO/site and MPO/microliter GCF were both greater at gingivitis and periodontitis sites than at healthy sites. Enzyme activity was similar at the 2 categories of diseased sites. Mean GCF volume and MPO activity were calculated for all samples from healthy, gingivitis and periodontitis sites with GI 0, 1, 2 and 0 + 1. GCF volume, MPO/site and MPO/microliter GCF all were greater at GI 2 than GI 0 or 0 + 1. These data indicate that increased GCF MPO previously observed at periodontitis sites is not specific to such sites. Rather increased GCF MPO likely occurs when additional polymorphonuclear leukocytes enter the sulcus as a result of gingival inflammation. A second sample was obtained from 22 sites 4 weeks after the initial collection. These samples were collected for 5 s rather than 30 s. The GCF volume, MPO/site and MPO/microliters GCF were each greater in samples collected for 30 s rather than 5 s. Correlation coefficients showed that the amount of GCF and MPO activity of the fluid collected for 5 s and 30 s was dependent upon the site even though the 5-s and 30-s samples were collected 4 weeks apart.