Influence of Nd:YAG and diode laser irradiation on apical sealing when associated with AH plus and EndoREZ endodontic cements

OBJECTIVE: This study aims to evaluate the influence of Nd:YAG and diode laser irradiation on apical sealing when applied before root canal filling done with two different resin-based cements (AH Plus and EndoREZ). Background Data: Lasers have been widely used in endodontics. The morphologic changes in dentin walls caused by Nd:YAG and diode laser irradiation could improve sealing ability of endodontic cements. METHODS: Eighty canine teeth were analyzed by apical leakage of methylene blue dye and by scanning electron microscope (SEM) images of the filling's adaptation to the apical third dentin walls. The laser irradiation parameters for the Nd:YAG laser were 100 mJ, 15 Hz, and 1.5 W, and for the diode laser was 2.5 W (continuous mode). RESULTS: The apical leakage results showed statistically significant differences at the 5% level of significance (Tukey's test, p < 0.05) among the different root canal wall treatments, independently of the root canal filling cement used. The cements also showed significant differences between them on the lased groups. The SEM analysis revealed better filling adaptation for AH Plus and the Nd:YAG laser group, confirming the microleakage results. CONCLUSION: We concluded that the combination of the Nd:YAG laser and AH Plus showed the best results.     

Computer-assisted evaluation of microleakage after apical resection with laser and conventional techniques

The purpose of this in vitro study was to observe the morphological changes and apical dye penetration at apical dentin surfaces after apicoectomy with conventional techniques and laser beam. Sixty single-rooted extracted teeth were selected for the study. The crowns were resected below the cemento-enamel junction. Then, these teeth were treated endodontically and filled with gutta-percha using AH-26 root canal sealer. The teeth were randomly divided into four groups of 15 teeth in each. The roots were resected perpendicular to its long axis 3 mm from the apex using Er: yttrium–aluminium–garnet (YAG) laser irradiation in groups 1 and 2, and the resected root surfaces were lased with Nd:YAG laser in group 2. The apexes were resected by a high-speed handpiece in groups 3 and 4, and the resected root surfaces were lased with Nd:YAG laser in group 4. Ten teeth in each group were used for leakage studies, and the other five teeth were used for scanning electron microscopic examinations. Seven sections were obtained from each root to assess the microleakage, and the sections were analyzed in a computer-assisted manner. No statistically significant differences were observed between the leakage percentage of groups 1 and 3 and groups 2 and 4 (p > 0.05). Morphological differences were observed between apical dentin surfaces resected with conventional techniques and laser beam.     

Radiographic evaluation of periapical status and prevalence of endodontic treatment in an adult Japanese population.

OBJECTIVES: To determine the prevalence of periapical radiolucencies and endodontic treatment in an adult Japanese population. STUDY DESIGN: Periapical status and length of root fillings of 672 adult patients attending Okayama University Hospital of Dentistry were evaluated using full mouth intraoral radiographs. RESULTS: Overall, 87% of the subjects had root-filled teeth, and 70% exhibited an apical radiolucency. Of the 16,232 teeth examined, 21% had been root-filled, and, of these, 40% exhibited an apical radiolucency. Root-filled teeth that were overfilled or that were mandibular incisors had the highest prevalence of apical radiolucencies. CONCLUSIONS: The prevalence of root-filled teeth appears higher in this Japanese population than in Europe or America; however, the ratio of teeth with an apical radiolucency to root-filled teeth was within the range of that reported for other countries. Overfilled teeth and mandibular incisors are most likely to exhibit apical radiolucencies.     

Effect of rotary or manual instrumentation, with or without a calcium hydroxide/1% chlorhexidine intracanal dressing, on the healing of experimentally induced chronic periapical lesions.

OBJECTIVE: To evaluate the healing of experimentally induced chronic periapical lesions in dogs at 30, 75, and 120 days after root canal instrumentation with rotary NiTi files or manual K-files, with or without a calcium hydroxide/1% chlorhexidine paste intracanal dressing. STUDY DESIGN: The second, third, and fourth mandibular premolars and the second and third maxillary premolars of 5 dogs (12 to 18 months of age, weighing 8 to 15 kg) were selected for treatment (a total of 82 root canals). After pulp removal, the root canals were left exposed to the oral cavity for 7 days to allow microbial contamination, after which the root canals were sealed with ZOE cement until periapical lesions were confirmed with radiography. Group I and II teeth were instrumented with manual K-files using the crown-down technique. In group III and IV teeth, NiTi rotary files were used. The apical delta was perforated by using #20 to #30 K-files at the length of the tooth, thus creating a standardized apical opening. The apical stop was enlarged to size 70, with 2.5% sodium hypochlorite irrigation at each file change. Teeth in groups II and IV were dressed with calcium hydroxide (Ca(OH) 2 )/1% chlorhexidine (CHX) paste for 15 days before root filling. Group I and III teeth did not receive an intracanal dressing. The access openings of the teeth were permanently restored with silver amalgam condensed on a glass ionomer cement base. Pairs of standardized periapical radiographs were taken at the beginning of the treatment (0 days) and at 30, 75, and 120 days after filling. RESULTS: There was no significant difference in the rate of radiographic healing of the periapical lesions between manual and rotary instrumentation. Radiographs taken at 120 days showed that the treatment with Ca(OH) 2 /1% CHX paste resulted in a significant reduction in mean size of the periapical lesions in comparison to single-session treatment. These findings were also true for histologic observations. CONCLUSION: The findings support the hypothesis that, regardless of the instrumentation technique (manual or rotary), the use of an intracanal dressing is important in the endodontic treatment of dog's teeth with experimentally induced chronic periapical lesions.     

Epithelium and bacteria in periapical lesions.

OBJECTIVE: The purpose of this study was to evaluate 50 human periapical lesions for bacteria and epithelium in a case study in dental practice. STUDY DESIGN: Specimens were obtained from the extraction of 50 untreated teeth that had lesions attached to their apices. The specimens were histologically evaluated using serial sections. RESULTS: Bacteria were found in all teeth, colonizing necrotic tissue in the main canal, dentinal tubules, or apical ramifications, and in the body of the periapical lesion in 18 abscesses or cysts. Twenty-one lesions were epithelialized; 14 abscesses, 20 granulomas, and 16 cysts were distinguished. In 18 root canals inflamed tissue was found in the apical part of the canal. A single foramen was present in 13 cases while apical ramifications were found in 37 cases. CONCLUSIONS: Granulomas were most common, and most epithelialized lesions were cysts. Bacteria were only detected periapically in abscesses or cysts. Inflamed tissue was present in the apical root canal in one third of cases.     

Microleakage evaluation of intraorifice sealing materials in endodontically treated teeth.

OBJECTIVE: Evaluate intraorifice sealing materials Cavit, Vitremer, and Flow-It for the prevention of coronal microleakage in root-canal treatment. STUDY DESIGN: Root-canal treatment was performed on 80 extracted human molars. Three millimeters of coronal gutta-percha was removed from the coronal aspect of the root canal and replaced with one of the 3 filling materials. After thermocycling (5 degrees C to 55 degrees C) and 5 days of immersion in dye, the teeth were cleared for stereomicroscope evaluation for evidence of dye penetration into the sealing material and along canal walls. RESULTS: All groups showed dye penetration into the root canal. Cavit sealed significantly better than the other groups (P < .01), preventing the coronal leakage in 90% of the specimens. Flow-It exhibited the highest leakage (65% of specimens) and did not differ significantly from the Vitremer group, which showed dye penetration in 55% of specimens. CONCLUSION: Cavit sealed significantly better than Vitremer and Flow-It when used as intraorifice filling materials.     

Endodontic treatment outcome: effect of the permanent restoration.

OBJECTIVE: To investigate the relationship between the presence of the coronal restoration and endodontic treatment success or failure. METHODS: This study comprised 200 endodontically treated teeth with 441 roots. Follow-up examination was conducted 4 +/- 0.5 years after completion of endodontic treatment. Outcome criteria were modified from Strindberg. RESULTS: Teeth/roots restored with permanent coronal restoration (casting or filling) had a higher success rate (80%) than teeth/roots not restored (60%; P < .01) in the analysis of aggregate data. However, the results of stratified analysis on key confounding factor (preoperative periapical diagnosis) showed that there is no significant association between the presence of permanent restoration and endodontic outcome. Teeth with preoperative apical periodontitis were less likely to be restored with a crown (23.9%) than teeth without apical periodontitis (76.1%; P < .01). Anterior teeth were more likely to be restored with a filling and sooner than the posterior teeth. These associations suggest a treatment selection bias. CONCLUSIONS: Stratified analysis on the key confounding factor reveals that endodontic outcome is driven by the presence of preoperative root canal infection (apical periodontitis). Lack of stratification on key confounding factors inaccurately suggests that presence of permanent restoration contributes to the success of endodontic treatment in the aggregate analysis of grouped data. The choice to restore the tooth as well as the choice and timing of permanent restoration may be the result of a bias in treatment selection. Stratified analysis on key confounding factors is the key to valid analysis and accurate results.     

Periapical health related to the type of coronal restorations and quality of root canal fillings in a Turkish subpopulation.

OBJECTIVE: The purpose of this study was to evaluate the relationship between the quality of root canal fillings and type of permanent coronal restorations and their association with the periapical status in a Turkish subpopulation. STUDY DESIGN: There were 1268 endodontically treated teeth from 280 panoramic radiographs that were evaluated. Two observers assessed the radiographs using an x-ray viewer with 2 times magnification. Teeth were classified according to the type of restorations. The quality of root canal fillings were evaluated according to the criteria determined by Tronstad et al. Apical status was assessed by the Periapical Index scores (PAI) proposed by ?rstavik et al. Chi-square test was used for statistical analysis. RESULTS: There were 59.5% of endodontically treated teeth that showed healthy periapex. Teeth with good endodontic treatment showed statistically significant high healthy periapex rates regardless of the type of the restoration. In addition, the evaluation of the entire material also showed that the roots with posts had significantly more periapical pathosis than roots without posts (P = .001). CONCLUSIONS: It can be concluded that, although the quality of the root canal filling plays a key role in the outcome of endodontic therapy, the type of restoration can also be a contributing factor in the treatment outcome.     

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.     

口腔根管治疗176例牙髓根尖周病的临床疗效分析

目的:对口腔根管治疗(Root Canal Therapy,RCT)在牙髓根尖周病中的临床效果进行分析,探讨RCT失败的原因。方法:通过对采用RCT的176例牙髓根尖周病患者的临床资料进行回顾性研究,对临床中根管填充质量及治疗结果进行分析。结果:采用RCT的221颗患牙中适充率、欠充率和超充率分别为199例(90.0%)、10例(4.5%)及12例(5.4%);治疗2周后成功率和失败率分别为201例(91.0%)、20例(9.0%),治疗1年后成功率和失败率分别为198例(89.6%)、23例(10.4%),治疗2周后与治疗1年后的成功率相比较,差异无统计学意义(P>0.05)。结论:RCT失败的主要原因是医源性因素、根管欠充以及根管超充;RCT具有临床效果好、成功率高的优点,值得临床广泛应用。     

Effect of a calcium hydroxide-based root canal dressing on periapical repair in dogs: a histological study.

OBJECTIVE: To compare the periapical repair of teeth with periapical lesion following root canal treatment by using a calcium hydroxide-based intracanal dressing for several time periods or filling in a single visit. STUDY DESIGN: After induction of periapical lesions in 4 dogs, the root canals were prepared using 5.25% sodium hypochlorite for irrigation, and animals were separated into 4 experimental groups; in group I, root canals were filled in a single session; in groups II, III, and IV, a calcium hydroxide-based dressing was kept in place for 15, 30, or 180 days, respectively. Root canals from groups I, II, and III were filled with gutta-percha cones and AH Plus sealer. After 180 days, animals were killed and histological sections were stained with hematoxylin-eosin to evaluate periapical repair. RESULTS: Periapical repair was better in groups II, III, and IV (intracanal dressing) compared with group I (single session; P < .05). CONCLUSION: The use of a calcium hydroxide-based intracanal dressing was important for periapical repair in teeth with periapical lesion. Dressing with calcium hydroxide paste results in better periapical repair than when the root canal is filled in a single-session treatment.     

Evaluation of periapical repair following retrograde filling with different root-end filling materials in dog teeth with periapical lesions.

OBJECTIVE: The objective of this study was to evaluate periapical repair following retrograde filling using different root-end filling materials. STUDY DESIGN: After induction of periapical lesions, 48 root canals from dog teeth were partially filled. Endodontic surgery was performed and 3 different materials were used for root-end filling: Sealer 26, Sealapex plus zinc oxide, or mineral trioxide aggregate (MTA). No additional procedures were performed in the control group after partial filling of the root canal. After 180 days, the animals were killed, the maxillas and mandibles were removed, and specimens were submitted for histologic processing. RESULTS: Histopathologic analysis revealed similar periapical repair for the groups in which Sealer 26, Sealapex plus zinc oxide, and MTA were used (P > .05). The control group showed unsatisfactory periapical repair (P < .05). CONCLUSION: There was no difference in periapical tissue healing after retrograde filling with the tested materials, which indicates that these 3 root-end filling materials are equally useful.     

Digital imaging analysis with mathematical morphology and fractal dimension for evaluation of periapical lesions following endodontic treatment.

OBJECTIVE: To see if a method for digitizing trabecular pattern of bone could be used to quantitatively evaluate changes in bone pattern following endodontic treatment of teeth with periapical osteolytic lesions. STUDY DESIGN: Periapical radiographs were digitized and further processed with mathematical morphology operations known as skeletonization. The trabecular patterns resulting from this skeletonization process were further analyzed with fractal dimension analysis using box-counting. RESULTS: The periapical area in digitized radiographic images showed fractal behavior. Twenty-five of 27 patients showed increase of the fractal dimension after root canal treatment. Significant changes of the box-counting could be noted 3 months after root canal treatment (P < .05). CONCLUSIONS: Mathematical morphology operation and box-counting might be helpful in early detection of changes of periapical trabecular pattern after root canal treatment.     

A study of periapical lesions correlating the presence of a radiopaque lamina with histological findings.

OBJECTIVE: To compare the presence or absence of a radiopaque lamina of 60 human periapical lesions with the histological findings from a case study in dental practice. STUDY DESIGN: Paralleling radiographs were taken of 60 teeth with periapical radiolucencies. The periapical radiographs were scanned, and standardized images were evaluated on a computer screen for the presence or absence of a radiopaque lamina by 2 calibrated observers according to agreed criteria. The serially sectioned histological specimens were obtained from the extraction of 13 endodontically treated teeth and 27 nontreated teeth, as well as 20 post-treatment teeth with apical periodontitis removed during periapical surgical procedure; the specimens were classified according to agreed criteria. The findings of the 2 evaluations were compared. RESULTS: Out of 57 electronic images that could be interpreted, 10 lesions had a radiopaque lamina, but of these only 3 were histologically diagnosed as cysts, while 7 were granulomas or abscesses. Out of 47 lesions without a radiopaque lamina, 40 were histologically diagnosed as granulomas or abscesses, while 7 were cysts. CONCLUSIONS: The diagnosis of periapical lesions cannot be made on the basis of the presence or absence of a radiopaque lamina, but requires histological examination of serial sections.     

Effects of intracanal carbon dioxide laser irradiation on cultured human fibroblasts.

OBJECTIVE: The purpose of this study was to evaluate, under various conditions, the damage that might occur to viable cells after CO2 laser irradiation of the root canal. STUDY DESIGN: A laser tip was placed within the root canal of extracted human teeth that were positioned above cultured fibroblasts (NB cells), and then irradiation was applied. The irradiation modes used were either pulse (40 pps) or super-pulse (151 pps). The laser energy was set at 32 J in both modes, and the tip of the laser beam was positioned to a point 2 mm from the fibroblasts. RESULTS: When the pulse mode irradiation was applied, there was significant difference (P < .05) in the percentage of viable cells between teeth with closed apical foramen (1-mm wall between root canal and root apex) and the #15 group (No. 15 K-file used), #30 group (No. 30 K-file), or #50 group (No. 50 K-file). The difference between the #30 group and the #50 group (P < .05) was also significant. The larger the diameter of the apical foramen became, the lower was the percentage of viable cells. CONCLUSION: If a CO2 laser irradiates a root canal system enlarged to within 1 mm of the root canal length, little damage to the periapical tissues would be expected to occur.     

桩腔预备的不同时机对两种根管封闭剂根尖封闭性的影响

目的：通过比较根尖微渗漏的长度来观察即刻桩腔预备和延迟桩腔预备对两种根管封闭剂根尖封闭性的影响。方法：将120颗上颌单根管牙齿以ProTaper手用镍钛根管锉逐步深入法根管预备,随机分为A、B两组,每组60颗。分别用AHplus糊剂、Cortisomol糊剂加牙胶尖热侧向加压法进行根管充填。根充后根据桩腔预备情况将A、B两组随机再分为A1、A2、A3和B1、B2、B3 3个亚组,每组20颗。A1、B1组即刻行桩腔预备,A2、B2组1周后行桩腔预备,A3、B3组为对照组未行桩腔预备。染料渗透法测量微渗漏距离并进行统计学分析。结果：两组牙齿根尖部均有微渗漏产生。采用单因素方差分析各实验组间微渗漏差异有统计学意义（F=19.2033,P＜0.01）,LSD-t检验对组间进行两两比较：两种根管封闭剂根充后延迟桩腔预备组和即刻桩腔预备组、对照组微渗漏差异有统计学意义（P＜0.01）。延迟桩腔预备不同封闭剂充填组之间微渗漏差异有统计学意义（P＜0.01）。其余各组之间微渗漏差异无统计学意义。结论：即刻桩腔预备对两种根管封闭剂的根尖封闭能力没有影响,延迟桩腔预备降低了根管封闭剂的根尖封闭能力;延迟桩腔预备中AHplus的根尖封闭性比Cortisomol好。     

Comparison of dentin root canal permeability and morphology after irradiation with Nd:YAG, Er:YAG, and diode lasers

The aim of this study was to compare the effects of Nd:YAG, Er:YAG, and diode lasers on the morphology and permeability of root canal walls. The three laser wavelengths mentioned interact differently with dentin and therefore it is possible that the permeability changes caused will determine different indications during endodontic treatment. Twenty-eight human single-rooted teeth were instrumented up to ISO 40 and divided into four groups: group C, control (GC), non-laser irradiated; group N (GN), irradiated with Nd:YAG laser; group E (GE), with Er:YAG laser and group D (GD) with diode laser. After that, the roots were filled with a 2% methylene blue dye, divided into two halves and then photographed. The images were analyzed using Image J software and the percentage of dye penetration in the cervical, middle, and apical root thirds were calculated. Additional scanning electron microscopy (SEM) analyses were also performed. The analysis of variance (ANOVA) showed significant permeability differences between all groups in the middle and cervical thirds (p < 0.05). The Tukey test showed that in the cervical third, GN presented means of dye penetration statistically significantly lower than all of the other groups. In the middle third, GE and GD showed statistically higher dye penetration means than GC and GN. SEM analysis showed melted surfaces for GN, clean wall surfaces with open dentinal tubules for GE, and mostly obliterated dentinal tubules for GD. Er:YAG (2,094 nm) laser and diode laser (808 nm) root canal irradiation increase dentinal permeability and Nd:YAG (1,064 nm) laser decreases dentin permeability, within the studied parameters.     

Histologic evaluation of periradicular tissues in dogs treated with calcium hydroxide in combination with HCT20 and camphorated P-chlorophenol.

OBJECTIVE: The aim of this study was to evaluate the biocompatibility of calcium hydroxide suspended in HTC20 or calcium hydroxide plus CMCP and their effects on the healing of periapical lesions in dogs. STUDY DESIGN: Experimental apical periodontitis was induced by opening the pulp chamber of 36 mandibular premolars in 6 3-year old dogs. The teeth were left opened for 1 week and then closed with IRM for 60 days in order to induce periapical lesions. The teeth were divided into 1 control and 2 experimental groups. Both experimental groups received intracanal dressings with a calcium hydroxide slurry. In the first experimental group calcium hydroxide was mixed with a detergent vehicle and in the second group with camphorated parachlorophenol. The medications were kept in the root canal for 2 periods of 30 days each. Afterwards, the dogs were killed and the periapical areas were studied histologically. RESULTS: Based on biocompatibility and tissue remodeling in the periapical area, the best results were observed when calcium hydroxide was mixed with the detergent. The difference was statistically significant (P < .05). CONCLUSION: Calcium hydroxide plus CMCP intracanal dressing was the most irritating to the periapical region, and the group of calcium hydroxide plus HCT 20 showed the best results whenever biocompatibility and the capacity of new bone formation was considered.     

En face optical coherence tomography investigation of apical microleakage after laser-assisted endodontic treatment

The aim of our study was to evaluate the potential of en face optical coherence tomography (OCT) for the detection of apical microleakage after 980 nm and 1,064 nm laser-assisted endodontic treatment. Ninety, human, single-rooted teeth with one straight root canal and closed apices were used. All roots were prepared biomechanically to the working length at an apical size 30 and 0.06 taper. The teeth were divided into three equal groups of 30 samples each, according to the treatment to be applied to the root canal. Group I received 980 nm diode laser (3 W, 0.01 s on time, 0.01 s off time, 5 s per procedure, four procedures); group II received neodymium:yttrium–aluminum–garnet (Nd:YAG) laser (1.5 W, 15 Hz, 5 s per procedure, four procedures). In group III the root canals were approached conventionally only. In all groups the root canal filling was performed with AH Plus endodontic sealer and gutta-percha points. An en face OCT prototype was used for the investigation of apical microleakage. According to one-way analysis of variance (ANOVA) and en face OCT, the number of defects in the laser groups was significantly lower (P < 0.005) than in the control group. No statistical differences were noted between the laser groups (P = 0.049). En face OCT imaging proved that laser-assisted endodontic treatment improved the prognosis of root canal filling and led to a reduction in apical microleakage.     

纳米羟磷灰石糊剂封闭根管效果的实验研究

目的：利用实验研究纳米羟磷灰石糊剂结合牙胶尖封闭根管的效果。方法：选取46颗直根管的上前牙,其中40颗随机分为A、B两组（各20颗）,分别用纳米羟基磷灰石糊剂、AH-plus糊剂结合牙胶尖侧向加压技术充填根管。另外6颗牙齿用于阳性对照组c组（n=3）和阴性对照组D组（n=3）。采用染料渗透法测四组标本的染料渗入距离。结果：4组染液从根尖孔向冠方渗漏的直线距离分别为A组：（0．98±0．53）mm、B组;（1．46±0．32）mm、C组：（8．16±0．19）mm、D组：0mm,B组微渗漏值高于A组,两组间比较有显著差异性（P〈0．05）。结论：新型纳米羟基磷灰石糊剂封闭根管能力优于AH-plus糊剂,能够有效防止根尖微渗漏。