Comparison of positive-pressure, passive ultrasonic, and laser-activated irrigations on smear-layer removal from the root canal surface.

OBJECTIVE: The purpose of this study was to compare the efficacy of three irrigation techniques for smear-layer removal with 17% EDTA. BACKGROUND DATA: Cleaning and shaping the root canal system during endodontic treatment produces a smear layer and hard tissue debris. Three irrigation techniques were tested for solution infiltration of this layer: positive-pressure irrigation, passive ultrasonic irrigation, and laser-activated irrigation. MATERIALS AND METHODS: Sixty extracted teeth were divided into six equal groups; 17% EDTA was used for 60 sec irrigation of five of the groups. The groups were as follows: Group 1, treated only with ProTaper™ F3 Ni-Ti files; Group 2, positive-pressure irrigation, with a syringe; Group 3, passive ultrasonic irrigation, inserted 1 mm short of the working length; Group 4, passive ultrasonic irrigation, inserted in the upper coronal third of the root; Group 5, Er:YAG laser-activated irrigation, inserted 1 mm short of the working length; and Group 6, Er:YAG laser-activated irrigation, inserted in the upper coronal third of the root. RESULTS: Scanning electron microscopy showed that the smear layer is removed most efficiently using laser-activated irrigation at low energy with 17% EDTA, inserted either at the working length or only in the coronal upper third of the root. Amounts of Ca, P, and O were not significantly different on all treated dentin surfaces. CONCLUSIONS: Smear-layer removal was most effective when the root canals were irrigated using Er:YAG laser at low energy with 17% EDTA solution. Interestingly, removal of the smear layer along the entire canal was similar when the laser was inserted in the upper coronal third and at 1 mm short of the working length of the root canal. This effect was not observed with the ultrasonic and positive-pressure techniques.

Effect of Er:YAG laser-activated irrigation solution on Enterococcus Faecalis biofilm in an ex-vivo root canal model.

UNLABELLED: Abstract Objective: The purpose of this study was to evaluate mineral content and surface morphology of root canals coated with Enterococcus faecalis biofilm after treatment with several endodontic irrigation solutions, with and without Er:YAG laser-activated irrigation (LAI). BACKGROUND DATA: LAI has been introduced as a powerful method for root canal irrigation resulting in smear-layer removal from the root canal wall. METHODS: Distal and palatal roots from 60 freshly extracted human molars were used in this study. The coronal of each tooth was removed. Roots were split longitudinally and placed in an ultrasonic bath to remove the smear layer, creating conditions for the formation of E. faecalis biofilm. After incubation, the two halves were reassembled in impression material to simulate clinical conditions. Specimens were divided into two main groups: roots rinsed with irrigation solutions and roots subjected to laser irradiation combined with irrigation solutions. Solutions tested were 2% chlorhexidine and 17% ethylenediaminetetraacetic acid (EDTA) and saline. RESULTS: Surface morphology: 17% EDTA irrigant solution combined with Er:YAG laser showed the best results for removing bacteria from the root canal walls. Chemical analysis: all samples treated with combined laser irradiation and irrigation solution had low surface levels of Ca compared with samples treated with irrigation alone. The Ca/P ratio was highest in the laser-EDTA group. Overall, mineral changes caused by laser with irrigation solutions were minimal, and statistically nonsignificant. CONCLUSIONS: In vitro irrigation solutions, combined with Er:YAG laser irradiation, were effective in removing E. faecalis biofilm from root canal walls. Irrigation solutions without laser irradiation were less effective, leaving a layer of biofilm on the dentin surface.

Synergistic effect of Er:YAG laser irradiation in combination with chlorhexidine on the viability of Enterococcus faecalis: an in vitro study.

OBJECTIVE: This study aimed to examine the potential synergistic effect of laser and chlorhexidine (CHX) applications on the growth of Enterococcus faecalis. BACKGROUND DATA: CHX has been recommended for root canal irrigation because of its antibacterial properties. Er:YAG 2.94??m laser irradiation was shown to be beneficial in disinfecting infected root canals. Producing minimal side effects is the goal of any clinical procedure. One means of achieving this is via a synergistic effect caused by simultaneously introducing two applications with reduced dosages, with no compromise on their biological effect. METHODS: Bacterial suspensions of E. faecalis supplemented with 0.01?0.0001% v/v CHX solutions were lased at energy levels between 300 and 500?mJ. Bacterial growth was continuously monitored for 18?h using a GENios apparatus. RESULTS: Laser irradiation between 350 and 500?mJ delayed initiation of bacterial growth for 6?h. A concentration of 0.0001% CHX did not delay bacteria growth. However, a combination of 0.0001% CHX and laser irradiation had a synergistic effect on bacterial growth. A maximal inhibition period of bacterial growth was observed at energy levels of 500?mJ with 0.0001% CHX. CONCLUSIONS: Laser combined with CHX has a synergistic effect in killing E. faecalis. A combined regimen of a low concentration of CHX with laser irradiation was found to be a potential means of inhibiting bacterial growth.

Rapidly progressive internal root resorption: a case report.

The etiology of internal root resorption is not fully understandable, trauma and chronic pulpitis are considered the main risk factors. Usually the process is asymptomatic and diagnosed upon routine radiographic examination. This case report presents a rapid progression of internal resorption related directly to traumatic injury. A 16-year-old female arrived at the emergency room after a mild extrusion of the mandibular incisors. The initial treatment included repositioning and splinting of the teeth. Radiographs performed at repositioning and splinting demonstrated normal configuration of the incisor's roots. Ten months later progressive internal resorption of the left mandibular first incisor was diagnosed. While treating this tooth similar process was detected in the right mandibular second incisor and in the mandibular left second incisor. The lower right first incisor reacted inconsistently to vitality test. As a result of the severe and rapidly progressive nature of the process, root canal treatments were performed in all lower incisors. The follow-up radiographs demonstrate arrest of the internal resorption process.

The effect of CO2 Laser on the permeability of dentinal tubules: a preliminary in vitro study.

OBJECTIVES: The purpose of this in vitro study was to determine whether there is a change in dentin permeability following 9.6-microm CO(2) laser irradiation and high-speed drilling. MATERIALS AND METHODS: Twenty permanent, intact, non-carious molars were selected. The crowns were separated from the roots at the cemento-enamel junction. The teeth were randomly divided into two groups, control and experimental, each containing 10 teeth. After class I preparation using a high-speed drill, 9.6-microm CO(2) laser irradiation was applied to dentinal areas only on the experimental group. The samples were soaked in 0.5% methylene blue for 48 h; three independent examiners using scanning electron microscopy evaluated dye penetration through the specimens. RESULTS: The results of the three examiners were similar. There was a significant difference in dye penetration into dentin after laser irradiation versus controls (p < 0.05). CONCLUSIONS: The 9.6-microm CO(2) laser appears to be a promising tool in the clinical setting. However, further investigation is needed to ensure maximum effectiveness.

The effect of CO(2) laser on the microhardness of human dental hard tissues compared with that of the high-speed drill.

OBJECTIVE: The purpose of this study was to examine the effect of 9.6-microm CO(2) laser energy on the microhardness of human dental hard tissues compared with that of high-speed drill cavity preparation, and to determine the applicability of this laser in clinical treatment. MATERIALS AND METHODS: A total of 10 caries-free human single-rooted teeth were used for this study. The crowns were resected and the roots were longitudinally sectioned into two halves. In each slice one half of the enamel and the dentin were treated with 9.6-microm CO(2) laser irradiation, and in the other half the enamel and dentin were treated with a high speed drill, each half for 3 s. Following treatment, the samples were polished and tested for microhardness. The results were compared using analysis of variance. RESULTS: Statistically significant differences in dentin microhardness were found between specimens treated with 9.6-microm CO(2) laser energy as compared with specimens treated with the high-speed drill (p = 0.0156). There were no statistically significant differences in enamel microhardness between specimens treated with 9.6-microm CO(2) laser energy and specimens treated with the high-speed drill. CONCLUSION: The clinical use of 9.6-microm CO(2) laser energy for cavity preparation should be further analyzed, and compared with different types of lasers used in dentistry, such as 10.6-microm CO(2) or Er-YAG.