ABSTRACT
OBJECTIVE: The study aimed to evaluate the ability of optical coherence tomography (OCT) to guide and identify pulp exposure using an erbium: yttrium-aluminum-garnet (Er:YAG) laser. BACKGROUND DATA: The Er:YAG laser has been proven to be effective in ablating dental hard tissue and offers advantages, as there is none of the vibration and noise you get with conventional methods, but it has limitations in relation to the tactile feedback that would aid in identification of entry into the pulp chamber. Based on depth-resolved optical reflectivity, OCT technology has been developed to provide high-resolution, cross-sectional images of the internal structure of biological tissues. MATERIALS AND METHODS: The pulp chambers of 20 human mandibular incisors were examined, and the average thickness of hard tissue covering the pulp chamber was assessed using micro-computed tomography (micro-CT) images. An Er:YAG laser was used to gradually penetrate the hard tissue over the pulp chamber under microscopic guidance. The preparation was constantly imaged using a swept-source OCT at 10 sec intervals until a pulp chamber exposure was identified using the technology. The pulp exposure was re-examined under the microscope and compared with micro-CT images for verification. RESULTS: The pulp exposures of 20 incisors were all verified microscopically and with micro-CT images. The thickness of hard tissue penetrated by the laser ranged from 0.44 to 1.69 mm. CONCLUSIONS: Swept-source OCT is a useful tool for identifying pulp exposure during access opening with the Er: YAG laser.
Subject(s)
Dental Cavity Preparation/methods , Dental Pulp Exposure/diagnosis , Lasers, Solid-State , Tomography, Optical Coherence , Humans , Incisor , Root Canal PreparationABSTRACT
OBJECTIVE: The purpose of the present study was to investigate the degree of Er:YAG laser irradiation at the apical area in vitro. BACKGROUND DATA: Since the laser was developed, advancement of laser treatment has been seen in various fields. However, few reports exist on shaping of the root canal using Er:YAG laser irradiation. METHODS: Six single-rooted human teeth were used. The working length of root canals was set at 6.5 mm, and they were enlarged to apical file size #25. An Er:YAG laser and cone-shaped irradiation tips (R135T and R200T) were used. Laser irradiation conditions were 30 m J, 20 pps, and water flow of 5 mL/min. Samples were irradiated three times for 10 sec each using each tip. To evaluate the cutting degree of horizontal area of the root canal, the laser-irradiated surfaces were observed using microfocus X-ray computed tomographic photography before and after every irradiation. The samples were observed under a scanning electron microscope. Measurement of pixels in an area was performed by image-editing software (Adobe Photoshop 7.0). Statistical analysis was performed using StatView (version 5.0). One-way ANOVA and the Tukey-Kramer tests were used; p<0.05 indicated statistical significance. RESULTS: When root canals were irradiated with R200T for 10 sec (p<0.05), a large amount of evaporation (0.12 ± 1.07 mm(2)) was acquired in their cut area compared with the other irradiation conditions. In scanning electron microscopic observation, there was no smear layer and the dentinal tubules were open. CONCLUSIONS: When the distance between the tip and root dentin was adjacent, the shaping of root dentin by Er:YAG laser irradiation was definitely observed.
Subject(s)
Lasers, Solid-State/therapeutic use , Root Canal Preparation/methods , Dental Pulp Cavity/pathology , Humans , In Vitro Techniques , Microscopy, Electron, ScanningABSTRACT
OBJECTIVE: The purpose of this in vitro study was to evaluate the effect of surface modifications induced by erbium (Er):YAG and neodymium (Nd):YAG laser irradiation on cell adhesion by comparing it to that of conventional methods for surface preparation after root-end resection. BACKGROUND DATA: Many studies have been seeking a favorable method to produce a resected root end with optimal conditions for cell response. However, little improvement has been achieved. This study evaluated the biocompatibilities of resected root surfaces after Er:YAG or Nd:YAG laser irradiation on initial cell adhesion. MATERIALS AND METHODS: Dentin disks were divided into three groups. Group A was left untreated, Group B was treated with Er:YAG laser irradiation (60 mJ/pulse, 10 pps, 60 sec), and Group C with Nd:YAG laser irradiation (60 mJ/pulse, 10 pps, 60 sec). After laser irradiation, the dentin disks were incubated with NIH/3T3 fibroblasts cultured in Dulbecco's modified Eagle's medium. A morphological analysis of the dentin surface and cell adhesion was observed under a scanning electron microscope. Surface roughness was measured using a confocal laser scanning microscope. The statistical analysis was undertaken using ANOVA at a level of significance of 5% (p<0.05). RESULTS: Morphological analysis and roughness measurement showed that dentin surfaces treated with Er:YAG laser irradiation were rougher than those in Groups A and C. Group B (Er:YAG) exhibited the greatest number of attached cells among all groups after 12 and 24 h. CONCLUSIONS: Morphological alteration induced by Er:YAG laser irradiation showed a favorable effect on the attachment of fibroblasts to dentin surfaces.