Disinfection effectiveness of photodynamic therapy combined with EDTA on infected lateral canals in vitro / 国际生物医学工程杂志

Objective:To investigate the disinfection effectiveness of photodynamic therapy (PDT) combined with ethylenediaminetetraacetic acid (EDTA) disodium salt solution on enterococcus faecalis in lateral root canals.Methods:Sixty-four human single root canal premolars were selected to prepare artificial root canal collaterals, and E. faecalisin root canal collateral infection models were established. The infection model was divided into PDT group ( n=16), PDT combined with EDTA group ( n=16), positive control group ( n=16) and negative control group ( n=16) according to random number table method. In the PDT group, 40 μg/ml hematoporphyrin monomethyl ether was injected into the root canal, and then the root canal was irradiated with a 45 mW laser for 90 s after 5 min incubation. In the PDT combined with EDTA group, the root canal was given 5 ml EDTA solution with 17% mass fraction for 1 min, and then treated with the method same as the PDT group. In the positive control group, the root canal were given 5 ml NaClO solution with a mass fraction of 5.25 % for 1 min. In the negative control group, the root canal were given NaCl solution with a mass concentration of 9 g/L for 1 min. Before and after the treatments, samples were taken in the lateral branches of the root canal with a K file to count plate colonies. After treatments, the roots of each group were placed in sterile brain heart infusion broth (BHI) medium for anaerobic culture for 24 h, and then sampled with a K file, and the number of root canal collaterals was detected statistically. Scanning electron microscopy was used to observe the morphology of the inner wall of lateral branches of root canals after treatments. Results:The sterilization rate of PDT combined with EDTA group was 99.56%, which was significantly higher than that of negative control group (1.98%), positive control group (85.87%) and PDT group (87.53%), the differences were statistically significant (all P<0.05). The reply experiment shows that the number of infection root canals was only 5, which was less than the negative control group (15), positive control group (12) and PDT group (11), and the differences were statistically significant (all P<0.05). Scanning electron microscopy observations showed that no obvious E. faecalis adhered to the inner wall of root canal of PDT combined with EDTA group. Conclusions:PDT combined with EDTA has a good disinfection effectiveness on E. faecalis in lateral canals, and it is expected to provide a new method for the effective killing of E. faecalis in lateral canals in clinical root canal therapy.

Nd:YAG Laser therapy device for caries control and prevention and its influence on temperature of isolated tooth pulp chamber / 国际生物医学工程杂志

Objective To analyze the influence of a dental caries phototherapy device using neodymium-yttrium-aluminum-garnet (Nd:YAG) laser on the temperature of tooth pulp chamber of different sites and morphologies under different irradiation duration and power. Methods Fifty intact isolated teeth were collected and randomly divided into middle incisor group, upper right first premolar group, upper right second molar group, upper left first premolar group, and upper left second molar group. Each experimental group was irradiated according to the laser power 1.5, 1.6, 1.7, 1.8, 1.9 and 2.0 W, and the irradiation duration 30, 60, 90 s. The temperature rise of the pulp chamber was recorded with a thermocouple thermometer. Results After the laser irradiation, the temperature of the tooth pulp chamber increased, and the temperature rise was less than 5.5℃, i.e. the threshold leading to the dental pulp necrosis. Conclusions The use of laser to prevent dental caries will increase the temperature of the tooth pulp chamber, but the temperature rise in the range of 5.5 ° C is relatively safe and will not cause irreversible damage to the pulp tissue.

Effect of laser treatment of dentin hypersensitivity on pulp chamber temperature / 国际生物医学工程杂志

Objective To compare the pulp chamber temperature changes of Nd:YAP laser, Nd:YAG laser and semiconductor laser with the same power during dentin hypersensitivity treatment, and to evaluate the safety of these three laser treatments for dentin hypersensitivity. Methods 50 intact third molars were collected to prepare the dentin hypersensitivity model. The samples were randomly divided into Nd:YAP laser group (n=15), Nd:YAG laser group (n=15), semiconductor laser group (n=15), and blank control group (n=5). Each experimental group was divided into three subgroups (n=5) of 0.9 W, 1.4 W, and 1.8 W according to the laser power. The experiments were conducted with the corresponding laser parameters and thermocouple thermometer was used to record the temperature changes in the pulp chamber. The control group does not do any processing. After laser irradiation, one sample was randomly taken from each group and the morphology of dentin tubules was observed by scanning electron microscopy. Results When different power lasers were used to irradiate the samples, the temperatures of the pulp chamber in each group were increased. Among them, the temperature rise of the pulp chamber was smallest in the Nd:YAP laser group, followed by the semiconductor laser group, and the temperature rise was highest in the Nd:YAG laser group, but it was still lower than 5.5 ° C that could cause pulp necrosis. Scanning electron microscopy results showed that after irradiation with different power lasers, the diameters of most dentinal tubules in the Nd:YAG laser group and the semiconductor laser group were narrowed or even melted, and the effect was better than that of the Nd:YAP laser group. Conclusion The treatment using Nd:YAP laser, Nd:YAG laser and semiconductor laser for dentin hypersensitivity will increase the temperature of the pulp chamber. However, the temperature rise is less than 5.5℃and that will not cause irreversible damage to the pulp tissue. Nd:YAG laser and semiconductor laser have better dentinal tubule blocking effect, which is more suitable for laser dentin desensitization treatment than Nd:YAP laser.

Effects of pulsed Nd:YAG laser radiation on marginal microleakage of porcelain-fused-to-metal crowns / 国际生物医学工程杂志

Objective To study the effects of pulsed Nd:YAG laser radiation on the marginal microleakage of porcelain-fused-to-metal crowns. Methods Twenty in vitro premolar teeth were selected and processed by standard porcelain crown preparation. The porcelain-fused-to-metal crowns were made based on the relevant repair technical requirements. The restorations were randomly divided into control group (group A) and experimental group (group B). The restorations in the group B were treated by external Nd:YAG laser irradiation with power of 1.25 W and irradiation time of 20 s. All the restorations were fixed with composite resin cement, and then put into normal saline under 37℃for 20 d, during which 300 times thermal cycling were performed. After that, the restorations were placed into 0.5％ pinkish red solution for 24 hours to dyeing, and then dissected along the longitudinal axis. The marginal microleakage of the restoration was observed by a stereomicroscopy. The data were processed by the SPSS 19.0 software. Results The degree of marginal microleakage of the restorations after Nd:YAG laser irradiation was significantly lower than that in the control group (P<0.05). Conclusions The pulsed Nd:YAG laser irradiation can effectively improve the adhesion between the resin and the hard tissue of the teeth, and reduce the marginal microleakage of the porcelain-fused-to-metal crowns.

Effects of photodynamic therapy for dental caries prevention on trace elements in tooth enamel / 国际生物医学工程杂志

Objective To study the application of photodynamic therapy (PDT) for dental caries prevention using whole body luminescence fiber,and to investigate the effects of PDT on the content of Ca and P in rat molar enamel.Method The rat dental caries model was established by inoculating with S.mutans.Eighty male rats were randomly divided into five groups,including three experimental groups:17 mW (8 mW/cm2) PDT (group A),34 mW (15 mW/cm2) PDT (group B),68 mW (30 mW/cm2) PDT (group C),a positive control group:20 g/L NaF solution (group D),and a negative control group:0.9％ physiological saline (group E).The experimental groups were treated by 40 μg/mL hematoporphyrin monomethyl ether (HMME) and 650 nm diode laser irradiation.The experiments were conducted for 4 weeks.The contents of Ca and P in the molars of each group were measured by inductively coupled plasma emission spectrometry.Results The contents of Ca and P in group B,C and D after PDT were significantly higher than those in group A and E (all P＜0.05).The contents of Ca and P in group A showed no significant difference before and after PDT,while those in groups B and C showed significant increase after PDT (all P＜O.05).The increment of Ca in group A after PDT was lower than that in group D (P＜0.05),while those in group B and C were significantly higher than those in group D (all P＜0.05).There was no significant difference in the increment of Ca and P between group B and C after PDT.Conclusions In the range of the experimental parameters,the PDT promoted effect of tooth remineralization is better than 20 g/L NaF.The levels of Ca and P in the tooth enamel can be promoted by PDT treatment,and the contents of Ca and P are related to the pewer of PDT.The effect of low power PDT on the remineralization of enamel is not obvious.The contents of Ca and P in the tooth enamel are increased with laser power of PDT.When the laser power increased to a certain value,the change in contents of the two elements is not obvious.PDT can maintain the tooth remineralization microenvironment.

Effect of 532 nm picosecond Nd∶YAG laser irradiation on temperature of the pulp chamber / 国际生物医学工程杂志

Objective To preliminarily select safe parameters for different forms of teeth by irradiating 532 nm picosecond Nd∶YAG laser on human isolated teeth with different irradiation time length and power.Methods Isolated human teeth including anterior teeth,premolars,molars were irradiated with 532 nm picosecond laser.Repeated measurements were made for each tooth by thermometer to measure the temperature of pulp chamber on different time point and power,and the temperature change (△T) was calculated.Results △T of the anterior irradiation group at 0.6 W,30 s;0.8 W,20 s and 30 s;1.0 W,10 s,20s and 30s were more than 5.6 ℃,which was the same with that of premolar group at 1.0 W,30s.△T of the molar group at 1.0 W,30 s was less than 5.6 ℃.Under certain power,the temperature of pulp chamber increased with the prolonging of irradiation time (P＜0.05).At a certain time,temperature increased with the power (P＜0.05).Conclusions It is safe to carry out operation on the parameters setting of 0.8 W,10 s and 0.6 W,20 s irradiation for anteriors teeth;0.4 W,30 s,0.8W,30 s and 1.0 W,20 s for premolar teeth,and 1 W,30 s for molar teeth.In the application of 532 nm picosecond laser,attention is required to be paid on parameter setting to control input power and irradiation time.

Photodynamic therapy of oral pathogenic bacteria and its potential application / 国际生物医学工程杂志

Photodynamic therapy (PDT) has been wildly used in the treatment of tumors and dermatologic diseases,especially,when the traditional therapies are ineffective or bring side effects.Moreover,with the deepening of the studies,its effects in anti-microbial has been found.PDT in the treatment of infectious diseases has attracted more and more attention of scholars.In this review,we discussed the mechanism of the PDT,studies in the sterilization of a variety of oral pathogenic bacteria by the PDT and its potential applications in clinic.

Antibacterial efficacy of HMME-PDT on Enterococcus faecalis within infected simulated lateral canals in vitro model with different energy / 国际生物医学工程杂志

Objective The purpose of this study was to assess the antibacterial effects of hematoporphyrin monomethylether-photodynamic therapy (HMME-PDT) on Enterococcus faecalis within infected simulated lateral canals in vitro with different energy.Methods Simulated lateral canals were prepared on extracted teeth.The specimens were infected with Enterococcus faecalis and then were randomly divided into eight groups.Group A was considered as negative control,its specimens were irrigated with physiological saline.Group B was the positive control,they were irrigated with 5.25％ NaClO.Other groups were incubated with HMME at concentration of 40 μg/ml for 5 min,followed by exposure to light at 532 nm for 120 s with different powers in a spiral pattern.Groups were named C-H,in corresponding with the power 50,60,70,80,90,100 mW.Microbial samples (the dentin chips from simulated lateral canals) were taken before and after the treatments.The survival fractions in each simulated lateral canal was calculated by counting colony-forming units(CFUs).Results 1.The HMME-PDT-treated groups resulted in a significant reduction in the number of E.faecalis in simulated lateral canals compared with the negative controls(P＜0.05).2.The antibacterial effects of group D、E、F、G、H were higher than the NaCl0-irrigated group(P＜0.05).3.The difference of antibacterial effects between the F、G、H groups was in significant(P＞0.05).Conclusion HMME-PDT had significant inhibitive efficacy on Enterococcus faecalis within infected simulated lateral canals and the efficacy was power-depended.It can play the best effect with the power of 80 mW.

The change of serum ischemia modified albumin level in continuous ambulatory peritoneal dialysis patients / 中国医师进修杂志

Objective To observe the change of serum ischemia modified albumin (IMA) in continuous ambulatory peritoneal dialysis (CAPD) patients.Methods Seventy-four end stage renal disease patients undergoing CAPD more than 3 months (CAPD group) were divided into 2 groups according to clinical symptoms of cardiovascular diseases:CAPD symptoms group (29 cases) and CAPD asymptomatic group (45 cases).Seventy healthy subjects were selected as control group.The serum IMA level and abnormal rate of electrocardiogram and heart color ultrasonic were examined and compared.Results The serum IMA level in CAPD group was significantly higher than that in control group [(92.33 ± 17.17) kU/L vs.(69.63 ± 9.24)kU/L,P＜ 0.01].The serum IMA level in CAPD symptoms group was significantly higher than that in CAPD asymptomatic group [(109.37 ± 21.34) kU/L vs.(85.31 ± 8.58) kU/L,P ＜ 0.05].The elevatory rate of serum IMA level and abnormal rate of electrocardiogram and heart color ultrasonic in CAPD symptoms group were significantly higher than those in C APD asymptomatic group [37.9％ (11/29) vs.15.6％(7/45),62.1％ (18/29) vs.22.2％ (10/45),P ＜0.05].Conclusions The serum IMA level in CAPD patients is elevatory.Serum IMA level is significantly higher in CAPD patients with cardiovascular disease clinical symptoms,it can be used for diagnosis of myocardial damage in CAPD patients.

Study of the effective of efflux pump inhibitors in photodynamic therapy inhibition the cariogenic bacteria in dental plaque biofilms / 国际生物医学工程杂志

Objective To Study the effect of efflux pump-inhibitors(EPI)-Verapamil in photodynamic therapy (PDT) using hematoporphyrin monomethylether (HMME) as photosensitizer on the cariogenic bacteria in dental plaque biofilms.Methods According to the administrator order of the verapamil and photosensitizer in PDT,streptococcus mutans,streptococcus sanguis,eosinophilic lactobacillus and actinomyces viscosus were used to establish the dental plaque biofilm model.The experiment was divided into five groups,group A was incubated with the photosensitizer and verapamil group,group B using verapamil before incubated the photosensitize,group C suing photosensitizer before incubated verapamil,group D with PDT only,group E was control group.After laser treatment,the influence of the dental plaque biofilms was observed by confocal laser scanning microscope.Results As saline-treated group is a group of normal the dental plaque biofilms.In PDT only group,compared with the saline group,red fluorescence increased significantly,the bacteria lose accumulation capacity,and were isolated and scattered in dispersed state.In PDT plus verapamil group,compared with only PDT group,green staining increased,bacterial activity increased.In group B,cells were incubated with verapamil before incubated the photosensitizer group,green staining increased significantly,red fluorescence reduced,indicating live bacteria increased,and bacteria activity was significantly increased.Conclusion PDT is an effective method in eliminating cariogenic bacteria of dental plaque biofilms.Bacterial efflux pump inhibitors can lower HMME-PDT inhibition cariogenic bacteria in dental plaque biofilm,and pre-verapamil administration could significantly inhibit the effect of PDT treatment of dental caries.

Effects of photodynamic therapy on the activity and structure of the dental plaque biofilms / 国际生物医学工程杂志

ObjectiveTo investigate the effects of photodynamic therapy(PDT) on the activity and structure of the dental plaque biofilm formed by the main cariogenic bacteria.MethodsS.mutans,S.sangius,L.acidophilus and A.viscosus were chosen as the experimental bacteria to establish dental plaque biofilm model.They were separated into three groups:group of PDT、group of chlorhexidine and group of normal saline.The influence of the dental plaque biofilms was observed according to plate counting of bacteria method.The changes in the structure of biofilms after PDT were analyzed by means of confocal laser scanning microscopy.Results Compared to normal saline group,chlorhexidine cariogenic bacteria (CFU/ml) in plaque biofilms significantly reduced (P＜0.05),with the bactericidal rate 57.84％.After PDT treatment against artificial caries model,the number of cariogenic bacteria (CFU/ml) in plaque biofilms reduced more significantly (P＜0.05),the bactericidal rate up to 94.92％,and the structure of dental plaque biofilns changed evidently.ConclusionPDT is an effective method in eliminate cariogenic bacteria of dental plaque biofilms and to destroy the integrity of dental plaque biofilms,and it is a promising method for elimination of dental plaque and prevention of caries.

Inhibitive effect of photodynamic therapy with different parameters on caries development in rats / 国际生物医学工程杂志

ObjectiveTo evaluate the inhibitive effect of Photodynamic therapy (PDT) with different parameters on dental caries formation in rats.MethodsWistar rats were infected with S.mutans to establish the rat caries mode 1.The rat's teeth were treated with 0.9% NS and 0.2% NaF as controls;laser,photosensitizer and laser plus photosensitizer,respectively as treated groups.Hematoporyrin monomethyl ether(HM ME) was used as photosensitizer and laser as the light source.The rats were sacrificed after five weeks.Keyes count was used to measure the inhibitory effect of PDT on dental caries.The surface morphology of the teeth was evaluated by scan electronic microscopy(SEM).Results The PDT-treated group and NaF-treated group showed significantly reduced Keyes scores compared with the negative controls (P＜0.05).The laser-treated group,photosensitizer-treated group and NS-treated group showed no significantly reduced Keyes scores compared with the negative controls (P＜0.05).The differences of Keyes scores between various parameter PDT treated groups were significant (P＜0.05).Additionally,Keyes scores reduced gradually with the increasing of laser power.The outcome of SEM showed that the teeth treated with different laser powers exhibited different changes in morphology.Conclusion HMMEPDT had significant inhibitive efficacy on caries development in rats and its inhibitory effect presented close correlation with the power of laser,which indicates that it is important to apply appropriate power in clinical treatment.