[Constructions of the scale of difficulty in the extraction of impacted mandibular third molars by using Delphi method].

OBJECTIVE: To evaluate the relevant indicators affecting difficulty in the extraction of impacted mandibular third molars and score difficulty of different operation and risk indicators, so as to build an intuitive and accurate scale to help operators make more accurate analysis and prediction of difficulty before the operation. METHODS: Based on literature and the clinical review, the difficulty indicators of tooth extraction were summarized. Firstly, 10 doctors from Peking University School and Hospital of Stomatology who had been engaged in alveolar surgery for a long time established an expert nominal group, and then rated whether the summarized indicators needed to be retained in the form of face-to-face questionnaires. A level 1 and 2 item frame for evaluating difficulty in the tooth extraction was formed after discussion; Then Delphi method was used to send a questionnaire to 30 experts by e-mail. After two rounds of scoring and modification, the scale of difficulty in the extraction of impacted mandibular third molars was formed. RESULTS: The recycling rate of two rounds of questionnaires was 100.0%, which showed that the experts were very enthusiastic about the study; The authority coefficients (Cr) of the two rounds of Delphi expert consultation were both 0.92, which showed that the results were representative and authoritative. After two rounds of grading and revision, the variable coefficient (CV) decreased and the Kendall's concordance coefficient (W) increased, which were statistically significant: In the first round, the CV was 0.24 and W was 0.56 (P < 0.001), and in the second, the CV was 0.19 and W was 0.72 (P < 0.001), which indicated that there was a good convergence among the expert opinions. Finally, a scale of difficulty in the tooth extraction containing 12 items at level A and 37 items at level B was formed, including operation difficulty indicators, risk difficulty indicators and common difficulty indicators. CONCLUSION: Based on comprehensive literature retrieval, the study has put forward the concept that difficulty in the extraction of impacted mandibular third molars is composed of operation difficulty and risk difficulty. Using Delphi method, the long-term clinical experience and professional knowledge of experts are transformed into quantitative indicators as a scoring scale. The scale has certain representativeness and authority.

Computer-aided three-dimensional assessment of periodontal healing distal to the mandibular second molar after coronectomy of the mandibular third molar: a prospective study.

BACKGROUND: The periodontal healing distal to the mandibular second molar (M2M) after coronectomy of the M3M has shown controversial results. We aimed to combine a digital method with cone-beam computed tomography (CBCT) and estimate periodontal healing of M2M after M3M coronectomy. An accurate and stable indicator in three dimensions was also explored tentatively. METHODS: Patients with a M3M in contact with the inferior alveolar canal were included. CBCT was applied immediately after coronectomy (baseline) and 6-months later. Data were investigated with digital software for registration. Previously reported and coronectomy-related factors were included for univariate and multivariate analyses. RESULTS: A total of 181 patients (213 M3Ms) completed 6-month follow-up. Significant reduction in the distal intra-bony defect (DBD) depth of the M2M was shown (1.28 ± 1.24 mm, P < 0.001). DBD depth of the M2M at baseline was the most influential factor (r = 0.59), followed by preoperative M3M condition, age, rotation and migration of the root complex. Remaining enamel (OR = 6.93) and small retromolar space (0.67) contributed to re-contact of the root complex and M2M. Bone volume regenerated in the distal 2 mm was associated significantly with DBD-depth reduction (r = 0.74, P < 0.001). CONCLUSIONS: Bone volume regenerated in the distal 2 mm of the M2M denoted stability of distal periodontal healing of the M2M. DBD depth at baseline was the most influential factor for healing of a DBD of the M2M after M3M coronectomy. The remaining enamel and a small retromolar space could contribute to re-contact of the root complex and the M2M. TRIAL REGISTRATION: China Clinical Trial Center, ChiCTR1800014862 . Registered 10 February 2018.

Effect of dietary roughage level on chewing activity, ruminal pH, and saliva secretion in lactating Holstein cows.

Increasing dietary roughage level is a commonly used strategy to prevent subacute ruminal acidosis. We hypothesized that high-roughage diets could promote chewing activity, saliva secretion, and hence more alkaline to buffer rumen pH. To verify the hypothesis, 12 multiparous Holstein cows in mid lactation were randomly allocated to 4 treatments in a triplicated 4 × 4 Latin square experiment with one cow in each treatment surgically fitted with a ruminal cannula. Treatments were diets containing 40, 50, 60, or 70% of roughage on a DM basis. Increasing dietary roughage level decreased DM, CP, OM, starch, and NEL intake, increased ADF intake, and decreased milk yield linearly. Intake of NDF was quite stable across treatments and ranged from 7.8 to 8.1 kg/d per cow. Daily eating time increased linearly with increased roughage level. The increase in eating time was due to increased eating time per meal but not number of meals per day, which was stable and ranged from 8.3 to 8.5 meals per day across treatments. Increasing dietary roughage level had no effect on ruminating time (min/d), the number of ruminating periods (rumination periods per d), and chewing time per ruminating period (min/ruminating period). Ruminating time per kilogram of NDF intake and total chewing time per kilogram of ADF intake were similar across treatments (57.4 and 183.8 min/kg, respectively). Increasing dietary roughage level linearly increased daily total chewing time; linearly elevated the mean, maximum, and minimum ruminal pH; and linearly decreased total VFA concentration and molar proportion of propionate in ruminal fluid. Saliva secretion during eating was increased, the secretion during rumination was unaffected, but the secretion during resting tended to decrease with increased dietary roughage level. As a result, total saliva secretion was not affected by treatments. In conclusion, the results of the present study did not support the concept that high-roughage diets elevated ruminal pH through increased salivary recycling of buffering substrates.

The composition, localization and function of low-temperature-adapted microbial communities involved in methanogenic degradations of cellulose and chitin from Qinghai-Tibetan Plateau wetland soils.

AIMS: To reveal the microbial communities from Qinghai-Tibetan Plateau wetland soils that have the potential to be used in the utilization of cellulosic and chitinous biomass at low temperatures (≤25°C). METHODS AND RESULTS: Soil samples collected from six wetlands on Qinghai-Tibetan Plateau were supplemented with or without cellulose and chitin flakes, and anaerobically incubated at 25 and 15°C; high-throughput 16S rRNA gene sequencing was used to access the composition and localization (in the slurry and on the surface) of enriched microbial communities; a hypothetical model was constructed to demonstrate the functional roles of involved microbes mainly at genus level. Overall, microbial communities from Qinghai-Tibetan Plateau wetlands showed significant potential to convert both cellulose and chitin to methane at low temperatures; Clostridium III, Clostridium XIVa, Paludibacter, Parcubacteria, Saccharofermentans, Pelotomaculum, Methanosaeta, Methanobrevibacter, Methanoregula, Methanospirillum and Methanosarcina participated in methanogenic degradation of both cellulose and chitin through the roles of hydrolytic, saccharolytic and secondary fermenters and methanogens respectively. Acetotrophic methanogens were mainly enriched in the slurries, while hydrogenotrophic methanogens could be both in the slurries and on the surface. CONCLUSIONS: The composition and localization of microbial communities that could effectively convert cellulose and chitin to methane at low temperatures have been revealed by high-throughput 16S rRNA gene sequencing methods, and reviewing the literatures on the microbial pure culture helped to elucidate functional roles of significantly enriched microbes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study will contribute to the understanding of carbon and nitrogen cycling of cellulose and chitin in cold-area wetlands and provide fundamental information to obtain microbial resources for the utilization of biomass wastes at low temperatures.

Efficacy and safety of miconazole for oral candidiasis: a systematic review and meta-analysis.

The objective of this study is to assess the efficacy and safety of miconazole for treating oral candidiasis. Twelve electronic databases were searched for randomized controlled trials evaluating treatments for oral candidiasis and complemented by hand searching. The clinical and mycological outcomes, as well as adverse effects, were set as the primary outcome criteria. Seventeen trials were included in this review. Most studies were considered to have a high or moderate level of bias. Miconazole was more effective than nystatin for thrush. For HIV-infected patients, there was no significant difference in the efficacy between miconazole and other antifungals. For denture wearers, microwave therapy was significantly better than miconazole. No significant difference was found in the safety evaluation between miconazole and other treatments. The relapse rate of miconazole oral gel may be lower than that of other formulations. This systematic review and meta-analysis indicated that miconazole may be an optional choice for thrush. Microwave therapy could be an effective adjunct treatment for denture stomatitis. Miconazole oral gel may be more effective than other formulations with regard to long-term results. However, future studies that are adequately powered, large-scale, and well-designed are needed to provide higher-quality evidence for the management of oral candidiasis.

In vitro antifungal effect and inhibitory activity on biofilm formation of seven commercial mouthwashes.

OBJECTIVE: To investigate the antifungal ability of seven over-the-counter mouthwashes against planktonic and sessile Candida albicans and Candida krusei. MATERIALS AND METHODS: The seven mouthwashes studied were Listerine, compound chlorhexidine solution, povidone iodine solution (PV-I), cetylpyridinium chloride solution, Colgate Plax, Crest Prohealth Mouthwash, and NaHCO3 . The antifungal ability of each mouthwash against ATCC90028, ATCC6258, and 10 clinical C. albicans isolates was tested using disk diffusion tests, the broth microdilution method, and biofilm testing with two different XTT-reduction assays. Fluconazole was used as a positive control, and the experiments were performed in triplicate. RESULTS: Chlorhexidine and cetylpyridinium chloride had the largest inhibition zones for ATCC90028 and ATCC6258 (18.6 ± 3.5 and 19 ± 1.6 mm, respectively). Cetylpyridinium chloride was the most effective at inhibiting all of the planktonic C. albicans strains and ATCC6258 with the minimum inhibitory concentration (MIC). As the maturity of the biofilms increased, the change in sessile cell MIC of the mouthwashes was much smaller than that of fluconazole. For the mature biofilms, chlorhexidine, PV-I, and cetylpyridinium chloride produced the greatest reductions in metabolism (60-80%). CONCLUSION: Most of these seven mouthwashes had significant antifungal activity for both planktonic and sessile Candida species.

[A comparative study of a two-stage surgical approach combining coronectomy with microimplant anchorage traction for extraction of impacted mandibular third molars with different traction angles].

Objective: To establish a two-stage surgical procedure of impacted mandibular third molars (IMTMs) extractions assisted by coronectomy and microimplant anchorage traction and to investigate the influencing factors of root movement and the effects of different traction angles on the clinical outcomes. Methods: Fifty-three IMTM in contact with inferior alveolar nerve (IAN) that underwent tooth extraction in the Peking University School of Stomatology from January 2022 to June 2023 were included, with coronectomy and microimplant anchorage implantation in the first stage of the surgery, root traction was achieved with orthodontic elastic and microimplant anchorages by about 600 g of force, when the IMTM root was detached from IAN, a second surgery was performed to extract the residual root. The basic information of patients and M3M, data on the microimplant anchorage implantation and traction, imaging measurements, and complications were recorded and analyzed. Results: The movement distance of the residual roots was (1.80±0.92) mm, and the duration of traction was (32.9±7.9) d. Multiple linear regression analysis showed that the residual root movement distance was significantly correlated with age, gender, number of roots, traction angle, and depth of the distal bone defect of the second molar (P<0.05). The smaller the traction angle, the more significant the movement of the residual roots (P=0.044). In one case (1.9%, 1/53), the patient experienced abnormal sensation in the lower lip 16 days after traction. Conclusions: The two-stage surgical method of combined coronectomy with rapid traction technique to extract the IMTM allows for rapid movement of the residual root and reduces the risk of IAN injury. The efficiency of root movement can be accelerated by appropriately reducing the traction angle during surgery. The traction effect can be predicted based on indicators such as age, gender, number of roots and depth of distal bone defects of second molar.

[Properties of gelatin-polyethylene glycol hydrogel loaded with silver nanoparticle Chlorella and its effects on healing of infected full-thickness skin defect wounds in mice].

Objective: To explore the properties of gelatin-polyethylene glycol hydrogel loaded with silver nanoparticle (AgNP) Chlorella (hereinafter referred to as the composite hydrogel) and its effects on healing of infected full-thickness skin defect wounds in mice. Methods: The research was an experimental research. The simple gelatin-polyethylene glycol hydrogel (hereinafter referred to as the simple hydrogel) and the composite hydrogel were prepared, and the appearance and injectability of the two hydrogels were observed at 55 and 37 ℃, and under the irradiation of 808 nm near-infrared light, respectively. An electronic universal testing machine was employed to assess the tensile and compressive stress-strain properties of both types of hydrogels at room temperature. Additionally, the cyclic compressive stress-strain properties of the composite hydrogel were examined at 80% of the maximum compressive stress. Staphylococcus aureus or Escherichia coli solution was added to phosphate buffer solution (PBS), simple hydrogel, and composite hydrogel, respectively. The part of composite hydrogel containing Staphylococcus aureus or Escherichia coli solution was irradiated with near-infrared light for 5 minutes. After each sample was incubated for 6 h, the dilution plating method was used to detect and calculate the mortality rates of the two bacteria at 24 h of culture (n=5). The discarded foreskin tissue was taken from a 6-year-old healthy boy admitted to the Department of Urology of the First Affiliated Hospital of Naval Medical University for circumcision. Primary human fibroblasts (HFbs) were isolated using the enzyme extraction method, routinely cultured to the 3rd to 6th passages for subsequent cellular experiments. Composite hydrogel extracts with final mass concentrations of 100.0, 50.0, 25.0, 12.5, and 0 mg/mL were respectively prepared and used to culture HFbs, and the cell proliferation after 24 h of culture was detected using a cell counting kit 8 (n=3). A total of twenty 6-8 weeks old C57BL/6J female mice were utilized, and a full-thickness skin defect was surgically created on the back of each mouse. The wounds were infected with Staphylococcus aureus solution. The infected mice were divided into blank control group, simple hydrogel group, composite hydrogel group, and combined treatment group according to the random number table, and the wounds were treated with PBS, simple hydrogel, composite hydrogel, and composite hydrogel+light irradiation (under the irradiation of 808 nm near-infrared light for 5 min), respectively, with 5 mice in each group. On post injury day (PID) 0 (immediately after the first wound treatment), 3, 7, and 14, an overall assessment of wound exudation and healing were conducted, and the wound healing rates on PID 7 and 14 were calculated (n=5). On PID 14, hematoxylin-eosin staining was performed to observe histopathological changes in the mouse wound. Results: Both simple hydrogel and composite hydrogel were in a solution state at 55 ℃ and transition to a gel state when cooling to 37 ℃. After the two hydrogels were irradiated by near-infrared light, only the composite hydrogel reheated up and returned to the solution state again with injectability. The maximum tensile stress of the composite hydrogel was up to 301.42 kPa, with a corresponding strain of 87.19%; the maximum compressive stress was up to 413.79 kPa, with a corresponding strain of 91.67%, which was similar to the tensile and compressive properties of the simple hydrogel. After 10 compression cycles, the maximum compressive stress of the composite hydrogel still reached 84.1% of the first compressive stress. After 24 h of culture, the mortality rate of Staphylococcus aureus treated with simple hydrogel was significantly higher than that treated with PBS (P<0.05); the mortality rates of Escherichia coli and Staphylococcus aureus treated with composite hydrogel alone were significantly higher than those treated with simple hydrogel (P<0.05); the mortality rates of Escherichia coli and Staphylococcus aureus treated with composite hydrogel+light irradiation were significantly higher than those treated with composite hydrogel alone (P<0.05). After 24 h of culture, compared with that cultured in composite hydrogel immersion solution with final mass concentration of 0 mg/mL, the proliferation activity of HFbs cultured in composite hydrogel immersion solution with final mass concentrations of 25.0 and 50.0 mg/mL was significantly enhanced (P<0.05), while the proliferation activity of HFbs cultured in composite hydrogel immersion solution with final mass concentration of 100 mg/mL was significantly decreased (P<0.05). On PID 0 and 3, more purulent secretions were seen in the wounds of mice in blank control group and simple hydrogel group, while only a small amount of exudate was observed in the wounds of mice in composite hydrogel group, and no obvious infection was observed in the wounds of mice in combined treatment group. On PID 7 and 14, the wound healing rates of mice in simple hydrogel group were significantly higher than those in blank control group (P<0.05); the wound healing rates of mice in composite hydrogel group were significantly higher than those in simple hydrogel group (P<0.05); the wound healing rates in combined treatment group were significantly higher than those in composite hydrogel group (P<0.05). On PID 14, the wounds of mice in blank control group exhibited a high infiltration of inflammatory cells with no new epithelial layer observed; the wounds of mice in simple hydrogel group displayed a short length of newly formed epithelium with a small amount of inflammatory cells; the wounds of mice in composite hydrogel group exhibited continuous formation of new epithelium and a large amount of immature granulation tissue; the wounds of mice in combined treatment group showed continuous epithelialization with less immature granulation tissue. Conclusions: The prepared composite hydrogel exhibits excellent thermosensitivity, photothermal properties, and injectability, as well as excellent mechanical properties, antibacterial properties, and biocompatibility, and can promote the healing of infected full-thickness skin defect wounds in mice.

Butyrate Inhibits Dendritic Cell Activation and Alleviates Periodontitis.

Dendritic cells (DCs) can mediate inflammation-related bone resorption that is crucial in the development of periodontitis. Butyrate is a critical by-product of microbes with antibacterial and anti-inflammatory properties. Here, we found that butyrate inhibited the activation of lipopolysaccharide (LPS)-induced DCs and generation of inflammatory cytokines by DCs. Moreover, butyrate regulated glycolysis in LPS-induced DCs via the G-protein-coupled receptor/hypoxia-inducible factor-1α pathway. In addition, butyrate inhibited the maturation of CD11c+MHC-II+ DCs in vivo, suppressing local inflammatory infiltration and ultimately alleviating bone resorption in a periodontitis model. Our results imply that butyrate suppresses the activation of LPS-induced DCs by modulating their metabolism, highlighting its potential as a therapeutic agent for inflammatory diseases.

[Clinical effects of ultra-pulsed fractional carbon dioxide laser in the treatment of mild to moderate microstomia after burns].

Objective: To investigate the clinical effects of ultra-pulsed fractional carbon dioxide laser (UFCL) in the treatment of mild to moderate microstomia after burns. Methods: A retrospective observational study was conducted on 19 patients with mild to moderate microstomia after burns who were admitted to Inner Mongolia Baogang Hospital from January 2018 to January 2022, including 15 males and 4 females aged (35±14) years. Patients had an average course of 71 d of microstomia, with 8 cases of moderate microstomia and 11 cases of mild microstomia. All the patients received UFCL treatment every 2-3 months until the microstomia was corrected or the treatment bottleneck was reached. The times of UFCL treatment for patients and the time interval from the last treatment to the last follow-up were recorded. Before the first treatment and at the last follow-up, the opening degree of mouth (finger measurement method), oral gap width, and the distance between the upper and lower incisors during mouth opening were recorded. Before the first treatment and at the last treatment, the new Vancouver scar scale (VSS) was used to evaluate the scar. At the last follow-up, the degree of satisfaction was evaluated by the Likert 5 scale by the patients themselves, and the satisfaction ratio was calculated; the adverse reactions such as pigmentation, blisters, infection, and persistent erythema in the treatment area were counted. Data were statistically analyzed with Mann-Whitney rank sum test or paired sample t test. Results: Patients received UFCL treatment of 3 (2, 6) times. The interval from the last treatment to the last follow-up was 26 months at most and 4 months at least. At the last follow-up, the opening degree of mouth of patients was significantly improved than that before treatment (Z=4.68, P<0.01). At the last follow-up, the oral gap width of patients was (35±6) mm, and the distance between upper and lower incisors during mouth opening was (3.2±0.4) cm, which was significantly improved compared with those before treatment (with t values of 10.73 and 18.97, respectively, P<0.01). The VSS score after the last treatment was 4.1±1.6, which was significantly better than that before treatment (t=22.96, P<0.01). At the last follow-up, the satisfaction ratio of patients with treatment was 18/19, and no pigmentation, blisters, infection, persistent erythema, and other adverse reactions of all patients in the treatment area occurred, however, one of the patients reported that the disease recurred about half a year after treatment. Conclusions: UFCL is an effective method for treating mild to moderate microstomia after burns, with which patients are highly satisfied, and it is worth of further study and promotion.

Three-dimensional assessment of root migration and rotation patterns after coronectomy: bone-embedded roots versus soft tissue-covered roots.

In this study, a three-dimensional evaluation was performed to explore differences between bone-embedded and soft tissue-covered roots after mandibular third molar (M3M) coronectomy. Patients were recruited according to the results of cone-beam computed tomography, 6 months after coronectomy. Completely bone-embedded M3Ms were assigned to group B, while completely soft tissue-covered M3Ms were assigned to group S. Data were recorded using digital software. A total of 213 M3Ms in 181 patients were investigated, of which 170 were assigned to the two study groups. Age was the primary factor influencing root migration (P<0.001). The smaller the degree of angulation of the M3M, the more likely was the root complex to rotate distally (r=-0.37, P<0.001). The depth of the impacted M3M contributed to the regeneration of new bone (P≤0.008). The length of the root complex (odds ratio 0.82, P=0.048) and distance from the root to the alveolar crest (odds ratio 1.23, P=0.026) were two critical factors influencing whether the root complex was bone-embedded. Ensuring that the length of the root complex is <7.6mm and the distance between the root and alveolar crest is ≥5mm were both found to be critical to the remaining root being completely bone-embedded and thus preventing eruption and the need for secondary surgery.

RNAi of Grp78 may disturb the fusion of ICR mouse palate cultured in vitro.

RNA interference (RNAi) is a powerful tool to silence or minimize gene expression, and palate culture in vitro is an important technique for study of the palate development. Our previous study demonstrated that the gene expression of glucose-regulated protein-78 (Grp78) was downregulation in the all-trans retinoic acid-induced mouse models of cleft palate (CP) during embryogenesis. To find the role of Grp78, the small interfering RNA (siRNA) of this gene carried by fluorescent vector was injected with a microinjector, through which about 30 pmol siRNA was injected into the Institute of Cancer Research (ICR) mouse palate explants. After 6, 12, 24, 48, and 72 h, these palate explants were removed from culture to observe their fluorescent and Alcian blue-staining phenotypes, and the expression of the unfolded protein response (UPR) key members (Grp78, Inositol-responsive enzyme 1, protein kinase RNA-like endoplasmic reticulum kinase, activating transcription factor-6 and X-box binding protein-1) was measured. After cultured for 72 h, the partially or completely fused bilateral palates were observed in the control siRNA group, while CPs were found in the Grp78 siRNA group. In the Grp78 siRNA group, the relatively mRNA abundance of the key genes belonged to UPR at each time point was lower than that of the control siRNA group, and their protein expression also displayed the same change. By the system of RNAi strategies with mouse palate culture, we found the siRNA of Grp78 disturbed the fusion of mouse palate cultured in vitro.

Effects of temperature on the fluoride release and recharging ability of glass ionomers.

This study investigated the effects of environmental temperature on the fluoride release and recharging ability of glass ionomers. Five disk specimens (15 mm in diameter and 1 mm thick) were made of each of the following materials: a conventional luting glass ionomer, two high viscosity restorative glass ionomers and a restorative resin-modified glass ionomer. The fluoride release of each material was measured at 4 degrees C, 37 degrees C and 55 degrees C. An additional three groups, which were made of the same materials, were stored in distilled and deionized water for 30 days and recharged in 250 ppm fluoride solution at 4 degrees C, 37 degrees C and 55 degrees C for five minutes. The fluoride re-release was measured daily from two days prior to two days after the recharging process. At all temperatures, the luting glass ionomers showed the greatest fluoride release and recharging ability, followed by the resin-modified glass ionomer, then the high viscosity glass ionomers. For each material, the fluoride release increased with increasing temperature and all glass ionomers showed greater recharging ability at higher temperatures. An increase in environmental temperature increased both the fluoride release and recharging of the glass ionomers. This may be important in developing regimes for improving the delivery of topical fluoride products.

[The measurement of pneumatization of maxillary sinus extended into alveolar process basing on the CT and its clinical significance].

Objective:To investigate the significance of pneumatization of maxillary sinus extended into alveolar process.Method:One hundred outpatients encountered were included in this study. The pneumatizations of maxillary sinus extended into alveolar process were observed and classified. Depth of surgical procedure of maxillary sinus in different type was measured.Result:The actual depth of surgical procedure of maxillary sinus of in different types of the alveolar process pneumatization varied greatly. The actual depth of surgical procedure of maxillary sinus in type Ⅲ pneumatization of alveolar process were (32.27±3.48)mm, which were significantly deeper than type Ⅱ (28.35±3.45)mm and type Ⅰ(20.73±3.09)mm (P< 0.05 respectively). Moreover, the actual depth of surgical procedure of maxillary sinus in type Ⅱ was also deeper than type Ⅰ(P< 0.05).Conclusion:The pneumatization of maxillary sinus extended into alveolar process can significantly affect the actual depth of the maxillary sinus in the operation of endoscopic middle meatus antrostomy, which may serve as a reference for the choice of endoscopic maxillary sinus approaches.

Smart materials in dentistry.

Most dental materials are designed to have a relatively 'neutral' existence in the mouth. It is considered that if they are 'passive' and do not react with the oral environment they will be more stable and have a greater durability. At the same time, it is hoped that our materials will be well accepted and will cause neither harm nor injury. This is an entirely negative approach to material tolerance and biocompatibility and hides the possibility that some positive gains can be achieved by using materials which behave in a more dynamic fashion in the environment in which they are placed. An example of materials which have potential for 'dynamic' behaviour exists with structures which are partly water-based or have phases or zones with significant water content and for which the water within the material can react to changes in the ambient conditions. Such materials may even be said to have the potential for 'smart' behaviour, i.e. they can react to changes in the environment to bring about advantageous changes in properties, either within the material itself or in the material-tooth complex. The controlled movement of water or aqueous media through the material may cause changes in dimensions, may be the carrier for various dissolved species, and may influence the potential for the formation of biofilms at the surface. Some of these issues may be closely interrelated. Clearly, materials which do not have the capacity for water transport or storage do not have the potential for this sort of behaviour. Some materials which are normally resistant to the healthy oral environment can undergo controlled degradation at low pH in order to release ions which may prove beneficial or protective. It is doubtful whether such behaviour should be classified as 'smart' because the material cannot readily return to its original condition when the stimulus is removed. Other materials, such as certain alloys, having no means of transporting water through their structure, can display smart behaviour by undergoing predictable changes in structure in response to applied mechanical or thermal stimuli. It has been difficult to harness such behaviour to the benefit of patients but progress in this area is slowly being made.

Inactivation of animal and human prions by hydrogen peroxide gas plasma sterilization.

Prions cause various transmissible spongiform encephalopathies. They are highly resistant to the chemical and physical decontamination and sterilization procedures routinely used in healthcare facilities. The decontamination procedures recommended for the inactivation of prions are often incompatible with the materials used in medical devices. In this study, we evaluated the use of low-temperature hydrogen peroxide gas plasma sterilization systems and other instrument-processing procedures for inactivating human and animal prions. We provide new data concerning the efficacy of hydrogen peroxide against prions from in vitro or in vivo tests, focusing on the following: the efficiency of hydrogen peroxide sterilization and possible interactions with enzymatic or alkaline detergents, differences in the efficiency of this treatment against different prion strains, and the influence of contaminating lipids. We found that gaseous hydrogen peroxide decreased the infectivity of prions and/or the level of the protease-resistant form of the prion protein on different surface materials. However, the efficiency of this treatment depended strongly on the concentration of hydrogen peroxide and the delivery system used in medical devices, because these effects were more pronounced for the new generation of Sterrad technology. The Sterrad NX sterilizer is 100% efficient (0% transmission and no protease-resistant form of the prion protein signal detected on the surface of the material for the mouse-adapted bovine spongiform encephalopathy 6PB1 strain and a variant Creutzfeldt-Jakob disease strain). Thus, gaseous or vaporized hydrogen peroxide efficiently inactivates prions on the surfaces of medical devices.

Ischemia/reperfusion alters uric acid and ascorbic acid levels in liver.

Tissue damage in ischemia/reperfusion injury may be mediated by oxidative stress caused by reactive oxidant species. Since such reactive species are difficult to measure directly, changes in antioxidant concentrations are often used as an indication of oxidative stress. In this study, microdialysis membranes were inserted into the livers of anesthetized rats to determine the effects of ischemia/reperfusion on the extra-cellular concentrations of two antioxidants, uric acid and ascorbic acid. Total hepatic ischemia was induced for 30 min by clamping the portal triad and was followed by 60 min of reperfusion. Uric acid and ascorbic acid concentrations were measured in microdialysis perfusates by high-performance liquid chromatography with electrochemical detection. Initial uric acid and ascorbic acid concentrations were high after insertion of membranes into the liver and decreased rapidly within 90 min (P < 0.001; ANOVA with repeated measures). Uric acid concentrations increased over 300% after ischemia and by 600% during the first 30 min of reperfusion (n = 8; P < 0.05). Ascorbic acid concentrations were 60% higher than controls after ischemia and 90% higher during the first 30 min of reperfusion (n = 8; P < 0.05). Alterations in concentrations of these redox-active molecules may be associated with oxidative stress in liver extracellular fluid during ischemia/reperfusion.