In vitro effects of endodontic irrigants on endotoxins in root canals.

OBJECTIVE: The objective of this study was to evaluate the effects of endodontic irrigants on endotoxins in root canals. STUDY DESIGN: Ninety-eight single-root human teeth were used. Escherichia coli endotoxin was inoculated into 84 root canals. All root canals were enlarged and assigned to 7 groups (n = 14), according to solution used. Group 1 (G1): 2.5% NaOCl; G2: 5.25% NaOCl; G3: 2% chlorhexidine; G4: 0.14% calcium hydroxide; G5: polymyxin B; G6: positive control, saline solution; G7: negative control (no endotoxin). Two samplings of root canal were accomplished: immediate and after 7 days. Detoxification of endotoxin was evaluated by Limulus assay and antibody production in B-lymphocyte culture. Results were analyzed by Kruskal-Wallis/Dunn and ANOVA/Tukey. RESULTS: At the immediate and second samplings, groups G4, G5, and G7 presented the best results, significantly different from groups G1, G2, G3, and G6 (P < .05). CONCLUSIONS: Calcium hydroxide and polymyxin B detoxified endotoxin in root canals and altered properties of LPS to stimulate the antibody production by B-lymphocytes. Sodium hypochlorite and chlorhexidine did not detoxify endotoxin.     

Temperature evolution on human teeth root surface after diode laser assisted endodontic treatment

The thermal rise threshold of an 810-nm semi-conductor diode laser on the root surface when used in root canals in vitro for laser assisted root canal treatment is investigated in this study. A total of 50 human single-rooted extracted teeth were included. For this study, the canals were enlarged up to an apical size of ISO#50 file. Laser irradiation was performed with six different settings. Specimens were irradiated at 0.6–1 W output power at the distal end of the fiber and about 1–1.5 W output power in the continuous mode (CW) as two groups. In the third group, 0.6–1 W output power, 10 ms pulse length (PL) and 10 ms interval duration (ID) were selected. In three other groups 1–1.5 W output power were used with different PL and ID as following: PL 10 and ID 10 ms, PL 10 and ID 20 ms and PL 20 and ID 20 ms. The total irradiation time was from 5 to 20 s per canal with a 200 m in diameter and 25 mm long tip. After laser treatment, the temperature changes at the outer root surface were registered by means of NiCr-Ni measuring sensors and a T 202 thermometer. The safe temperature threshold for applying this diode laser in root canal is considered as 7°C increase. To avoid increasing the temperature changes at the outer root surface related to this threshold, following total irradiation times were found: 0.6–1 W output power (10 ms PL/10 ms ID): 20 s (s), 1–1.5 W output power (10 ms/10 ms and 20 ms/20 ms): 15 s, 0.6–1 W output power CW and 1–1.5 W output power (20 ms PL/10 ms ID): 10 s and 1–1.5 W output power CW: 5 s. In the first three groups, 5 s irradiation and 5 s rest period avoided a temperature increase above the threshold of 7°C).     

Argon laser initiated resin photopolymerization for the filling of root canals in human teeth

This work was undertaken to determine if 488 nm light is transmitted through dentin in quantities adequate to polmerize resin located several milimeters from the light source (an optical fiber). The spread of polymerization in a camphorquinone activated resin due to 488 nm light emanating from an opaque plastic canal was compared with light emanating from a canal of the same diameter in tooth dentin. Results indicated that irradiation of a resin-filled chamber via an opaque canal generated a series of ellipsoidal forms, while irradiation via a root canal generated bullet-shaped forms of much larger volume and weight. The base of these bullet-shaped forms was flat against the dentin-resin interface and surrounded the canal. These results indicated that 488 nm argon laser light was transmitted through dentin and could act to polymerize resin at a distance of several millimeters from the canal. Further experiments verified that resin in lateral canals of tooth roots was readily polymerized by 488 nm light applied at low power levels (50 mW). These experiments demonstrate the effectiveness of the argon laser in polymerizing light activated dental resins located within or adjacent to tooth dentin at distances up to several milimeters from the fiberoptic terminus. The flexibility and control that these procedures make possible in the obturation of root canals may lead to substantial improvements in endodontic therapy.     

正畸治疗与牙根吸收

牙根吸收是正畸治疗过程中较常发生的并发症,错合畸形的矫治不是单纯的机械运动,而是复杂的生物机械运动。由于正畸过程中的某些因素如解剖因素、治疗因素等引起了牙骨质的过度吸收,从而形成了牙根外吸收（以下均称为牙根吸收）。Andreasen将牙根外吸收分为三类：①表层吸收；②炎性吸收；⑧替代性吸收。正畸源性的牙根吸收是典型的表层吸收，     

Risk of maxillary fungus ball in patients with endodontic treatment on maxillary teeth: a case-control study.

BACKGROUND: Maxillary sinus fungus ball (FB) is a noninvasive fungal disease commonly associated with symptoms of recurrent maxillary rhinosinusitis and/or extrusion of root canal filling material into the sinus. Chronic periapical inflammatory processes of dental origin are believed to be the risk factors in the pathogenesis of FB. The aim of this study was to determine whether endodontic treatment performed on maxillary molar, premolar, and canine teeth was a risk factor in the development of FB. METHODS: We designed a case-control study in which the cases were patients with FB admitted to the Department of Otorhinolaryngology at the University of Brescia between January 1990 and April 2005. For each case, 3 age-matched controls were randomly selected from the admission registry of the University Dental Clinic. Orthopantomography was used to detect endodontically treated maxillary molar, premolar, and canine teeth in both patients and controls. RESULTS: Of 102 patients with FB who were admitted during the study period, 91 (89.2%) had had endodontic treatment compared with 113 (36.9%) of 306 controls (chi square = 83.6601, P = 0.000; OR 14.13; 95% CI 7.25-27.54). The mean number (standard deviation; interquartile range [IQR]) of endodontic procedures was 1.39 (0.86; 1-2) in patients and 0.53 (0.81; 0-1) in controls (Mann-Whitney U test = -9.138, P = 0.0000). The interval between the endodontic treatment and the diagnosis of FB was available for 37 (36.3%) patients, and the median was 4 years (IQR 2-10). INTERPRETATION: Endodontic treatment on maxillary teeth is a strong risk factor for FB of the maxillary sinus.     

Time of endodontic treatment in autogenic transplants of mature teeth: histological study in dogs.

OBJECTIVE: Root canal therapy is often recommended after mature tooth transplantation. The aim of this work was to histologically evaluate, in dogs, the best time for root canal treatment in autogenic transplants of teeth with complete root formation. STUDY DESIGN: Mandibular lateral incisors of 8 dogs were extracted and transplanted to the homologous alveolus, endodontically treated after 15 (Group I) or 40 (Group II) days, and processed for routine histological evaluation. Tissue responses on the root surface were evaluated by light microscopy and classified as normal periodontium, active inflammatory root resorption, favorable healing, and unfavorable healing. RESULTS: The mean of normal periodontal tissue was in 88.6% in Group I and 79.4% in Group II. There were no significant statistical differences between the groups in all analyzed parameters. CONCLUSION: The results indicated that endodontic therapy can be postponed for 40 days postoperatively when the tooth stability is higher.     

A comparative study of temperature elevation on human teeth root surfaces during Nd:YAG laser irradiation in root canals

The purpose of this study was to evaluate the temperatures on the root surfaces during Nd:YAG laser irradiation in root canals using pulse durations of 180 and 320 μs. Thirty extracted human teeth were used in this study. The teeth were enlarged up to ISO 40 (multi-rooted) or up to ISO 60 (single-rooted) by conventional technique using K-files. Then the teeth were placed into a water bath with a constant temperature of 37 °C and then irradiated with an Nd:YAG laser having an output power of 1.5 W, a frequency of 15 Hz, using an optic fiber of 200 μm diameter. The temperature on the root surface was measured by means of attaching thermocouples in three areas (coronal, mesial, and apical regions) of the root canals. The thermographic study showed that the average temperature elevation for both pulse durations on the root surfaces was less than 9 °C. There was no significant difference in the observed temperatures in coronal and mesial areas. Though a higher increase of temperature was observed in the apical region when the pulse length of the Nd:YAG laser was 320 μs. The results of the study showed that the temperature rises during Nd:YAG laser irradiation with parameters used in this study minimal to cause damage on bone and periodontal tissues. Moreover, it was suggested that in order to have lower temperature in the apical region, an Nd:YAG laser with a pulse length of 180 μs is preferred than one with a pulse length of 320 μs.     

乳磨牙慢性根尖周炎的K3机用镍钛锉再治疗

目的:评价K3机用镍钛锉应用于乳磨牙慢性根尖周炎根管再治疗的临床效果。方法:收集下颌第一乳磨牙根尖周炎初次根管治疗失败患儿60例,随机分为两组,分别应用K3机用镍钛锉和手用不锈钢K锉进行根管再治疗,比较两组根管预备操作时间、根管充填质量、术后疼痛反应及再治疗后的临床疗效。结果:K3机用镍钛锉预备根管时间明显短于对照组,根充质量明显优于对照组,术后疼痛发生率明显低于对照组,近期临床疗效明显高于对照组,远期临床疗效两组之间无统计学差异。结论:K3机用镍钛锉预备乳磨牙根管快速而有效,值得临床推广使用。     

Interrelation between endodontic status, pathologic cemental granules and periodontal ligament adhering to the root of extracted teeth.

OBJECTIVES: To evaluate if the endodontic status has influence on the adherence of periodontal ligament (PDL) to extracted teeth and if the presence of "pathologic granules" is correlated to the endodontic status and/or the amount of adhering PDL. STUDY DESIGN: Extracted teeth with different endodontic status and exhibiting no marginal periodontitis were histologically examined. RESULTS: Observation of pathologic granules was related to a nonvital endodontium and to acute peroperative inflammation. Pathologic granules and denudation of the extracted roots were significantly related. Acute peroperative inflammation and low extraction forces were related to denudation of the roots. Such relation was not found for endodontic status, tooth type, root-form, and age of patients. CONCLUSION: The existence of pathologic granules in unexposed cementum is strictly related to teeth with a nonvital endodontium. There is no effect of the endodontic status on the adherence of PDL when an acute inflammation is absent.     

Antimicrobial photodynamic therapy combined with conventional endodontic treatment to eliminate root canal biofilm infection

BACKGROUND AND OBJECTIVE: To compare the effectiveness of antimicrobial photodynamic therapy (PDT), standard endodontic treatment and the combined treatment to eliminate bacterial biofilms present in infected root canals. STUDY DESIGN/MATERIALS AND METHODS: Ten single-rooted freshly extracted human teeth were inoculated with stable bioluminescent Gram-negative bacteria, Proteus mirabilis and Pseudomonas aeruginosa to form 3-day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify bacterial burdens. PDT employed a conjugate between polyethylenimine and chlorin(e6) as the photosensitizer (PS) and 660-nm diode laser light delivered into the root canal via a 200-micro fiber, and this was compared and combined with standard endodontic treatment using mechanical debridement and antiseptic irrigation. RESULTS: Endodontic therapy alone reduced bacterial bioluminescence by 90% while PDT alone reduced bioluminescence by 95%. The combination reduced bioluminescence by >98%, and importantly the bacterial regrowth observed 24 hours after treatment was much less for the combination (P<0.0005) than for either single treatment. CONCLUSIONS: Bioluminescence imaging is an efficient way to monitor endodontic therapy. Antimicrobial PDT may have a role to play in optimized endodontic therapy.     

两种根管冲洗方法对前牙侧支根管充填的影响

目的：对比根管超声冲洗和注射器冲洗对前牙侧支根管充填的影响。方法：在前牙根管治疗的患者中,选择有侧支根管的前牙160颗,随机平分为两组。A组根管预备时用超声冲洗;B组根管预备时用注射器冲洗。达到充填条件后用注射型Vitapex充填根管,观察侧支根管充填情况。结果：A组侧支根管充填率为77.5%,B组侧支根管充填率为25%,两组有明显差异（P〈0.01）。结论：超声冲洗可以较好地清洁根管,提高侧支根管充填率,提高了根管治疗的疗效。     

Photodynamic therapy for root canals infected with Enterococcus faecalis

OBJECTIVE: The aim of this study was to investigate the effects of photodynamic therapy (PDT) on endodontic pathogens by evaluating the decrease in numbers of Enterococcus faecalis colonies in the canals of extracted human teeth. BACKGROUND DATA: Failure in endodontics is usually related to inadequate cleaning and disinfection of the root canal system. This is due to the establishment of microorganisms in areas where the instruments and chemical agents used during root canal preparation cannot eliminate them. PDT is a complementary therapeutic method that could be used to eliminate these remaining bacteria. PDT is a process in which radiation acts on a dye that is applied to the target organism, resulting in bacterial death. MATERIALS AND METHODS: Forty-six uniradicular teeth had their canals contaminated with bacteria and were incubated for 48 h at 35 degrees C. After that, the teeth were divided into a control group (CG) and a test group (TG). The 23 CG teeth did not undergo any intervention, whereas in the TG the teeth received a solution of 0.0125% toluidine blue for 5 min followed by irradiation using a 50-mW diode laser (Ga-Al-As) at a wavelength of 660 nm. Bacterial samples were taken before and after irradiation. In each of the samples, the number of colony-forming units (CFU) was counted. RESULTS: The mean decrease in CFU was 99.9% in the TG, whereas in the CG an increase of 2.6% was observed. CONCLUSION: PDT was effective as a bactericidal agent in Enterococcus faecalis-contaminated root canals.     

Nonsurgical endodontic treatments in molar teeth with large periapical lesions in children: 2-year follow-up.

Profound caries lesions may lead to invasion of microorganisms to the dental pulp, and periapical areas can promote the development of dentoalveolar abscess and periapical bone loss. Treatment options to manage large periapical lesions range from nonsurgical root canal treatment and/or apical surgical procedure to extraction. Young molar teeth with pulp necrosis and large periapical lesions in children are frequently treated with root canal treatment because the therapy is more difficult in multirooted teeth. In these case reports, nonsurgical endodontic treatments performed on 6 molar teeth with large periapical lesions, by repeated intracanal dressing with calcium hydroxide, are presented. Radiographs displayed significant bony healing at the end of the second year. In conclusion, large periapical lesions can respond favorably to nonsurgical treatment, and complex and difficult endodontic treatments in children might not be required.     

年轻恒牙外伤后残根深埋治疗的修复学评价

目的:研究因年轻恒牙外伤后深埋其残根保留牙槽骨骨量,与传统拔除残根相比,为后期修复是否带来更好的效果。方法:选择秦皇岛市第二医院2001年1月～2009年9月口腔科收治的年轻恒牙外伤患者60例,共计90颗患牙。将其随机分为实验组和对照组,实验组病例(共计50颗患牙)深埋保留残根,临时修复,待牙根形成后,行完善的根管治疗桩冠修复,或拔出残根后固定修复;对照组病例(共计40颗患牙)拔除残根后临时义齿修复,成年后固定义齿修复。结果:实验组50颗患牙中有45颗修复成功,成功率为90.0%;对照组的40颗患牙中有33颗修复成功,成功率为82.5%,两种方法修复成功率有着明显的统计学差异(P<0.05)。结论:年轻恒牙深埋残根有利于牙槽骨及颌骨发育,为将来修复提供了良好基础,其效果明显好于传统拔除方法。     

Success rate of Sealapex in root canal treatment for primary teeth: 3-year follow-up.

OBJECTIVE: The aim of this study was to evaluate the clinical and radiographic success of Sealapex pulpectomies in primary teeth. STUDY DESIGN: Root canals of 62 primary teeth were filled with Sealapex. The tooth was restored with a stainless steel crown, amalgam, compomer, or glass ionomer cement. Clinical and radiographic evaluations of pulpectomized teeth were performed for up to 36 months afterward. RESULTS: The overall success rate was 92.3%. During the follow-up period, 4 teeth (7.7%) showing periapical lesion and pathologic resorption were extracted and rated as "failure." There were no statistically significant differences between success rate and extent of root canal filling material (P > .05). None of the fillings showed complete resorption in the canals. There were no significant differences among the restorative materials (P > .05). CONCLUSION: Based on the results of this study it can be concluded that Sealapex can be used successfully in root canal treatment for primary teeth.     

Nonsurgical retreatment of teeth with periapical lesions previously managed by either endodontic or surgical intervention.

OBJECTIVE: The purpose of this study was to evaluate the outcome of nonsurgical retreatment of teeth with periapical lesions, which had been previously managed by either endodontic or surgical intervention, and to identify factors that might influence the prognosis. STUDY DESIGN: Seventy-five endodontically and 11 surgically treated teeth with persisting periapical lesions ranging in size from 2 to 11 mm in diameter were included in this study. The teeth were nonsurgically retreated, using calcium hydroxide as intracanal medicament, and were followed for a period of 2 to 8 years. RESULTS: Clinical and radiographic assessment of retreatment showed that complete healing for all cases was 61.6% with an additional category of incomplete healing of 14%; 24.4% failed. The size of the periapical lesions and previous surgical treatment had marginally negative influences on the prognosis, but the differences were not statistically significant. CONCLUSION: The favourable results of this study demonstrated that nonsurgical root canal retreatment is an alternative to surgical intervention of postendodontic or postsurgical failure.