Cavity size difference after caries removal by a fluorescence-controlled Er:YAG laser and by conventional bur treatment

To determine the extensions of cavities prepared conventionally by bur or by a fluorescence-controlled Er:YAG laser. Sixty-five human teeth with dentine caries were bisected through the caries lesion and were treated by a fluorescence-controlled Er:YAG laser in a non-contact or a contact mode or by a rotary bur. The specimens were subjected to histological staining and a quantitative evaluation of cavity area (mm²) by computer-assisted alignment. Data were tested for statistical significant differences by the Wilcoxon test (p < 0.05). Twenty-three out of 29 cavities were smaller after caries removal with the non-contact laser compared to the bur. For a threshold level of seven, a cavity size difference of 1.63 (1.86) mm² was calculated compared to a cavity size difference of 5.35 (5.05) mm² after bur excavation. The differences were statistically significant (p = 0.029). No significant differences were observed between the cavity size differences after excavation with the non-contact or the contact laser handpiece. Residual bacteria within the cavity floor were found only in low numbers after all treatments. The present in vitro study indicates that caries removal by a fluorescence-controlled Er:YAG laser using a threshold level of seven resulted in less dentine loss than preparations by a bur.     

Evaluation of selective caries removal in deciduous teeth by a fluorescence feedback-controlled Er:YAG laser in vivo

This study investigated the ability and efficacy of an Er:YAG laser with a fluorescence feedback system for caries removal in deciduous teeth. Seventy-nine carious lesions were excavated using a fluorescence-controlled Er:YAG laser. Endpoint of treatment was defined by emission of fluorescence from the dentine surface below the pre-selected threshold level of 7 units and the subsequent termination of Er:YAG laser radiation. Dentine samples were obtained from the cavity floor, and viable counts of both Streptococcus mutans and Lactobacilli, expressed as colony forming units (log CFU), were evaluated. Preparation time was recorded to assess efficacy of the treatment procedure. S. mutans and/or Lactobacilli were found in 25 out of 79 lesions. Regarding the counts for S. mutans and Lactobacilli, the median log CFU was 0 (min, 0; max, 5.5) and 0 (min, 0; max, 6), respectively, with 2.4% of all samples yielding more than 100 CFU S. mutans and 4.8% yielding more than 100 CFU Lactobacilli. In 8 out of 79 cases, laser excavated cavities were not judged being caries-free using the conventional tactile criterion for assessing caries tissue. Focussing on these teeth, the median log CFU was 0 (min, 0; max, 0.5) for S. mutans and 0 (min, 0; max, 1.6) for Lactobacilli. The mean time for treatment was 2.3 +/- 1.2 min. Of the children, 93.8% rated the laser treatment to be comfortable. The study indicates that the fluorescence feedback-controlled Er:YAG laser might be an appropriate device for caries removal in children using the suggested threshold level of 7 units.     

Evaluation of selective caries removal by a fluorescence feedback-controlled Er:YAG laser in vitro

AIM: To establish a fluorescence threshold level that could guide a therapeutic Er:YAG laser through a caries lesion to determine a therapeutic endpoint of caries removal. MATERIALS AND METHODS: A total of 65 extracted human teeth, 35 with dentine caries and 30 healthy, were used for this study. An Er:YAG laser system that emitted at a wavelength of 2.94 microm was used. The laser was equipped with a laser fluorescence feedback system, excitation wavelength 655 nm, to control the irradiation by the Er:YAG laser. The evaluated threshold levels of the fluorescence feedback system were 3, 7, 8, 10, 12, 15 and 20. After treatment the teeth were prepared for histological staining according to the method of Brown and Brenn for the identification of bacteria. The specimens were subjected to a quantitative evaluation of residual bacteria on the treated dentine surface. In addition, the internal fluorescence of dentine and potential fluorescence changes of dentine after laser irradiation were evaluated. Results: About 80% of the irradiated dentine surface showed residual bacteria with threshold levels of 20, 15, 12, and 10. Residual bacteria were not found with threshold levels of 7 and 3. The study revealed a significant increase in dentine fluorescence after laser irradiation. Conclusion: The results of the present in vitro study indicate that a fluorescence threshold level of 7 or 8 units can guide an Er:YAG laser to a complete removal of carious dentine.     

Er：YAG 激光龋齿去腐对低龄儿童牙科焦虑症影响的初步观察

临床选取3岁±3月、乳磨牙(牙合)面Ⅱ度龋的患儿20例,随机分成试验组（激光组）和对照组（车针组,n ＝10）,在不使用开口器、束缚带的情况下分别用 Er：YAG 激光和车针去腐。观察患儿初诊、复诊时治疗成功率及畏惧程度。结果显示激光组治疗成功率高于车针组（P ＜0．05）,畏惧程度低于车针组（P ＜0．05）。激光治疗可缓解儿童牙科焦虑,有利于提高临床治疗成功率。     

Evaluation of selective calculus removal by a fluorescence feedback-controlled Er:YAG laser in vitro

OBJECTIVES: To evaluate the removal of subgingival calculus and dental hard tissues depending on the threshold level of a fluorescence feedback-controlled Er:YAG laser. MATERIAL AND METHODS: Twenty teeth with calculus on the root surface were treated with an Er:YAG laser. Laser settings were 140 mJ and 10 Hz. The initial fluorescence threshold level of 5 [U] was reduced at intervals of 1 [U] for every laser treatment. Areas of residual calculus (RC) were evaluated using a surface analysis software. Loss of dental hard tissues was assessed by histomorphometric analysis of undecalcified ground sections. RESULTS: Using a threshold value of 5 [U], the median amount of RC was 11% (0-78%). By lowering the threshold levels, the amount of RC decreased [level 1 [U]: 0% (0-26%)]. The laser-treated root surfaces revealed a statistically significant reduction of the cementum thickness [median: 80 microm (0-250)] compared with the non-treated opposite side [median: 90 microm (30-250)] (p<0.05). CONCLUSION: The amount of RC following laser irradiation depends on the fluorescence threshold level for a feedback-controlled Er:YAG laser. It might be suggested that this laser system may be used with a threshold level even lower than 5 [U] without removing a clinically relevant amount of root cementum.     

Er：YAG激光与传统机械去腐制备洞形的体外可行性比较

目的　为Er：YAG激光去除龋损和粘接修复的可行性提供更多的证据。方法　选取南京医科大学附属口腔医院口腔颌面外科门诊拔除的36颗龋坏深及牙本质的磨牙。每个离体牙的龋损都被切成大小相等的两份,分别纳入对照组(机械预备组)和实验组(Er：YAG激光组)。通过测量微拉伸粘接强度(mTBS)、微渗漏深度、观察组织学形貌、微观形态和测量操作时间比较了Er：YAG激光与传统机械法在这些方面的特性。结果　实验组的微拉伸粘接强度高于对照组(n=13,P<0.05),而平均微渗漏深度低于对照组,但差异无统计学意义(n=13,P>0.05)。实验组残留感染牙本质小管少于对照组(n=6,P<0.01)。扫描电镜观察显示,实验组牙本质小管开放、清晰、裸露,而经机械预备的牙本质表面有玷污层(n=4)。实验组的去龋时间明显长于对照组(n=36,P<0.05)。结论　虽然去龋时间较长,但Er：YAG激光用于窝洞预备较传统机械法有更高的微拉伸粘接强度和更少的感染牙本质小管残留。因此,Er：YAG激光是一种合适的临床去龋方法。     

Immunohistochemical study on pulpal response in rat molars after cavity preparation by Er:YAG laser

While Er:YAG laser systems are in extensive use for caries removal and cavity preparation, the effects of such treatment on pulp tissue remain unclear. This study evaluates these systems using immunohistochemical methods and compares the results with information gained from treatment using conventional burs. Cervical cavities were prepared in the upper first molars of rats, using either an Er:YAG laser or a conventional tungsten-carbide bur. At intervals of 5 min, 6 h, 12 h, 1 d, 3 d and 7 d after cavity preparation, the teeth were processed for immunohistochemical analyses of tissue non-specific alkaline phosphatase, OX6-positive major histocompatibility complex class II antigen-expressing cells and PGP 9.5-immunoreactive nerve fibers. DNA fragmentation was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. Tissue non-specific alkaline phosphatase was observed mainly in the subodontoblastic layer under the cavity lesion, from 5 min, in both groups. The immunoreactivity was more pronounced in the laser group, but by 7 d no significant differences were recognizable. At 12 h, TUNEL-positive cells were detected around the odontoblastic layer in both groups. From 3 d to 7 d, a limited number of positive cells were still visible in the group that underwent standard treatment. Clear similarities in the distribution patterns of OX6-immunopositive cells and PGP 9.5-immunoreactive nerve fibers were also noted. From 12 h to 1 d, OX6-positive cells accumulated along the pulp-dentin border, extending their processes into the dentinal tubules. Numerous bead-like PGP 9.5-immunoreactive nerve fibers were observed under the odontoblastic layer at 7 d. These results demonstrated that there was no appreciable difference in the manner in which pulp tissue responded to treatment with either Er:YAG laser or a conventional drill. This would seem to indicate the usefulness of the Er:YAG laser system in the removal of caries and cavity preparation.     

Er：YAG激光在龋病治疗时消除疼痛疗效观察

目的：探讨Er:YAG激光在龋病治疗中的止痛效果。方法：使用Er:YAG激光治疗9例龋齿、观察临床效果及疼痛情况。结果：治疗过程中实验组患者疼痛得分平均为0．22且均未麻醉,而牙钻组疼痛得分平均为1．6,且2例进行麻醉。结论Er:YAG激光可以较好地解决龋齿治疗中的疼痛问题。     

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??Objective    To compare clinical success rates of Er??YAG laser combined with different capping agents for direct pulp capping in primary teeth and evaluate the pain during treatment. Methods    A total of 60 teeth of 60 children between the age of 3 and 5 years were selected for this study. All the samples were randomly assigned to the following 4 groups??n=15???? Er??YAG laser+MTA??the exposed area was sealed with MTA after Er??YAG laser for caries removal and cavity preparation??Er??YAG laser+calcium hydroxide??CH????the treated area was sealed with CH paste after Er??YAG laser for caries removal??dental handpiece+MTA??the exposed pulp was sealed with MTA after dental handpiece for caries removal??dental handpiece+CH??CH was applied after dental handpiece for caries removal. The depth of cavity preparation was recorded while the child felt painful. At the 3-??6-??12-and 24-month recall examiations??the effect was observed by X-ray. Results    The proportion of the depth of cavity preparation??superficial dentin??middle dentin??deep dentin??by handpiece and Er??YAG laser was 50%??40%??10% and 0.67%??20%??79.33%??respectively. The two patterns of cavity preparation revealed significant difference??P < 0.05??. At the 3-??6-??12-month recall examiations??the success rates of the laser groups were higher than the handpiece groups??while they had no significant difference??P > 0.05??. At the 24 months??the success rates of the laser groups were 93.3%. They showed significantly higher success rates than the handpiece groups??P < 0.05??. The success rates of handpiece+MTA and handpiece+CH were 80%??12/15??and 73%??11/15????which did not reveal any significant difference. Conclusion        Er??YAG laser combined with pulp capping agents can be recommended for direct pulp therapy in primary teeth??and Er??YAG laser will result in a slight pain??thus the children will be inclined to accept and complete the treatment. The clinical effect of MTA shows no statistical difference compared with CH.     

Removal of partially erupted third molars using an Erbium (Er):YAG laser: a randomised controlled clinical trial

We compared Erbium (Er):YAG laser with a surgical bur for removal of partially erupted lower third molars. Patients were randomised to be treated by either laser or bur. A total of 42 patients (laser = 22; bur = 20) were treated. A greater reduction in the range of mouth opening was found after laser than after bur treatment. Postoperative pain was more common after bur treatment. The duration of operation was considerably longer with laser than with bur. No persistent complications were encountered.     

Scanning electron microscopy and Fourier transformed infrared spectroscopy analysis of bone removal using Er:YAG and CO2 lasers

BACKGROUND: A thorough analysis of laser-ablated bone tissue is required before applying the technique to osseous surgery. In this study, we examine the morphological features and chemical composition of the bone surface after Er:YAG and CO2 lasers ablation. METHODS: Six Wistar rats were used. An Er:YAG laser was used for ablation at an output energy of 100 mJ/pulse and a pulse rate of 10 Hz (1 W). Continuous CO2 laser irradiation was performed at an output energy of 1 W. Sites drilled using a conventional micromotor were used as controls. Analysis using scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) spectroscopy was performed. RESULTS: Er:YAG laser ablation produced a groove with similar dimensions to that produced by bur drilling, whereas the CO2 laser produced only a charred line with minimal tissue removal. SEM observations revealed that the groove produced by the Er:YAG laser had well-defined edges and a smear layer-free surface with a characteristically rough appearance and with entrapped fibrin-like tissue. The melting and carbonization produced by the CO2 laser were not observed on sites irradiated by the Er:YAG laser. FTIR spectroscopy revealed that the chemical composition of the bone surface after Er:YAG laser ablation was much the same as that following bur drilling. The production of toxic substances that occurred after CO2 laser irradiation was not observed following Er:YAG laser irradiation or bur drilling. CONCLUSION: These results suggest that the use of Er:YAG laser ablation may become an alternative method for oral and periodontal osseous surgery.     

Influence of the use of Er:YAG laser for cavity preparation and surface treatment in microleakage of resin-modified glass ionomer restorations

This study quantitatively assessed the amount of microleakage on Class V cavities prepared by Er:YAG laser and high-speed handpiece, varying the surface treatment and restoring with a resin-modified glass ionomer cement. Fifty cavities were prepared using either an Er:YAG laser device or a carbide bur at high speed. The surface treatment was performed as follows: Er:YAG laser irradiation (G1); 40% polyacrylic acid (G2); laser + acid (G3); finishing with low speed + laser + acid (G4); conventional bur preparation + acid (G5-control). The samples were restored with Fuji II LC, thermocycled, isolated and immersed in a 50% AgNO3 solution. The restorations were serially sectioned and the extent of dye penetration was measured in milimeters using specific computer software. Data were analyzed by two-way ANOVA and Tukey test. The lowest degree of microleakage was observed for G5, which was statistically similar (p>0.05) to G4 but different (p<0.05) from all the other experiental groups. Lesser microleakage was observed at the occlusal margins than at the cervical margins (p<0.05). It may be concluded that the use of Er:YAG laser for cavity preparation and surface treatment negatively affected the marginal sealing of resin-modified glass ionomer restorations.     

Er：YAG激光切除牙根断面的扫描电镜观察

目的对Er：YAG激光切除的牙根断面进行扫描电镜研究,并通过对比超声金刚砂尖以及高速涡轮金刚砂车针切除牙根断面的不同表面状态,为Er：YAG激光应用于临床根尖切除术提供依据。方法将30颗上颌中切牙随机分为3组（Er：YAG激光切除组、超声金刚砂尖切除组、高速涡轮金刚砂车针切除组）,分别使用Er：YAG激光、超声金刚砂尖以及高速涡轮金刚砂车针在距离根尖3 mm处进行牙根切除。使用扫描电镜观察3组牙根断面残屑及玷污层、牙本质小管开放、裂隙以及器械切割痕迹情况。结果Er：YAG激光切除组和超声金刚砂尖切除组牙根断面有少量残屑、玷污层,并有牙本质小管开放;高速涡轮金刚砂车针切除组牙根断面有大量残屑及玷污层,没有牙本质小管开放。高速涡轮金刚砂车针切除组中能看到大量裂隙出现,超声金刚砂尖切除组中可见裂隙出现,而Er:YAG激光切除组中几乎没有裂隙出现。高速涡轮金刚砂车针切除组和超声金刚砂尖切除组牙根断面的表面粗糙并有明显切割痕迹,而Er：YAG激光切除组牙根表面没有切割痕迹,较为平滑。结论Er：YAG激光应用于根尖切除具有一定的优势,其牙根断面组织形态学方面的表现明显优于超声金刚砂尖和高速涡轮金刚砂车针。     

Shear bond strength of two adhesive systems bonded to Er:YAG laser-prepared dentin

Dentinal surfaces prepared with an Er:YAG laser have distinctly different characteristics compared to those prepared with conventional instruments. The objective of this study was to evaluate the shear bond strength of a total-etch adhesive system and a self-etch adhesive system to dentin, prepared conventionally or with an Er:YAG laser. Specimens that were prepared with a diamond bur and treated with the total-etch adhesive showed the highest mean bond strength, followed by specimens prepared with the laser and treated with the total-etch adhesive, specimens prepared with a diamond bur and treated with the self-etch adhesive, and specimens prepared with the laser and treated with the self-etch adhesive, but there were no differences among the groups (P > 0.05). These data indicate that the tested adhesive systems promote similar shear bond strengths, whether the dentin is prepared with a diamond bur or an Er:YAG laser, and that an Er:YAG laser is a suitable cavity preparation method that promotes an adequate surface for a posterior adhesive procedure.     

CO2, ER:YAG AND ND:YAG LASERS IN ENDODONTIC SURGERY

Objectives:

CO₂, Er:YAG and Nd:YAG lasers have been used in endodontic surgery. This in vitro study evaluated 1% Rhodamine B dye penetration using computer-assisted morphometry (ImageTool Software®) of 108 endodontically treated human permanent canines.

Material and methods:

Teeth were divided into 9 groups according to the technique used: A: 90-degree apicoectomy with bur, root-end cavity preparation with ultrasound and filled with MTA; B: 90-degree apicoectomy with bur, root-end cavity prepared with ultrasound and filled with MTA, and treatment of apical surface with CO₂ laser (1 W, CW/CW); C: 90-degree apicoectomy with bur, and treatment of apical surface with Nd:YAG laser (150 mJ, 10 Hz); D: 90-degree apicoectomy with bur, and treatment of apical surface with CO₂ laser (1 W, CW/CW); E: apicoectomy with Er:YAG laser (400 mJ, 10 Hz), root-end cavity prepared with ultrasound and filled with MTA; F: apicoectomy with Er:YAG laser (400 mJ, 10 Hz) and treatment of apical surface with Nd:YAG laser (150 mJ, 10Hz); G: apicoectomy with CO₂ laser (5W, CW/SP), root-end cavity prepared with ultrasound and filled with MTA; H: irradiation of apical end with CO₂ laser (1 W, CW/CW); I: irradiation of apical end with Nd:YAG laser (150 mJ, 10 Hz).

Results:

Dye penetration was found in all specimens at different rates, the lowest penetration occurring in groups C (16.20%), B (17.24%) and F (17.84%).

Conclusions:

Groups B, C and F represent the best technical sequences to perform endodontic surgery.     

Er:YAG激光应用于口腔硬组织的研究进展

Er:YAG激光属于自由运行脉冲激光,在电磁波谱中属于中红外波段,其特定波长使得其可被水及羟基磷灰石吸收,可以更好作用于含水组织、牙体组织与骨组织.较传统临床操作而言,Er:YAG激光有切割精确、杀菌、愈合较快等特点.在牙釉质处理中,Er:YAG激光可以提高牙齿美白效能,延长窝沟封闭剂存留率及降低患龋率;在牙本质处理中...     

Performance of four dentine excavation methods in deciduous teeth

This in vitro study aimed to assess the speed and caries removal effectiveness of four different new and conventional dentine excavation methods. Eighty deciduous molars were assigned to four groups. Teeth were sectioned longitudinally through the lesion centre. Images of one half per tooth were captured by light microscope and confocal laser scanning microscopy (CLSM) to assess the caries extension. The halves were then reassembled and caries removed using round carbide bur (group 1), Er:YAG laser (group 2), hand excavator (group 3) and a polymer bur (group 4). The time needed for the whole excavation in each tooth was registered. After excavation, the halves were photographed by light microscope. Caries extension obtained from CLSM images were superimposed on the post-excavation images, allowing comparison between caries extension and removal. The regions where caries and preparation limits coincided, as well as the areas of over- and underpreparation, were measured. Steel bur was the fastest method, followed by the polymer bur, hand excavator and laser. Steel bur exhibited also the largest overpreparation area, followed by laser, hand excavator and polymer bur. The largest underpreparation area was found using polymer bur, followed by laser, hand excavator and steel bur. Hand excavator presented the longest coincidence line, followed by polymer and steel burs and laser. Overall, hand excavator seemed to be the most suitable method for carious dentine excavation in deciduous teeth, combining good excavation time with effective caries removal.     

Decontamination of Anodized Implant Surface With Different Modalities for Peri‐Implantitis Treatment: Lasers and Mechanical Debridement With Citric Acid

Background: Although oral rehabilitation with dental implants is a very promising and effective procedure, peri‐implantitis is an emerging concern. Surgical and non‐surgical methods have been applied to treat peri‐implantitis together with various implant surface decontamination methods. However, there is no consensus concerning the most effective treatment for peri‐implantitis. The aim of the present study is to evaluate the effects of erbium‐doped:yttrium, aluminum, and garnet (Er:YAG) laser, photodynamic therapy (PDT), and titanium bur with and without citric acid on ligature‐induced peri‐implantitis around an anodized implant surface. Methods: Thirty dental implants with anodized surface (3.3 × 10 mm) were installed in the mandibles of five beagle dogs. After 3 months, peri‐implantitis was induced by applying cotton ligatures subgingivally. After ligature removal (baseline), the implants were divided into the following treatment groups: 1) Er:YAG laser, 2) PDT, 3) titanium bur alone, and 4) titanium bur with citric acid. Animals were sacrificed after 3 months, and clinical, radiologic, histologic, and histomorphometric evaluations were conducted for all treatment modalities. The data were analyzed using one‐way analysis of variance and Tukey test. A value of P <0.05 was considered statistically significant. Results: The titanium bur with citric acid group exhibited statistically significantly greater improvement in vertical bone height than the Er:YAG laser group and significantly better bone‐to‐implant contact than the PDT group and the bur‐alone group. Conclusion: Within the limits of the study, the combination of mechanical and chemical treatment proved to be the most effective treatment for disinfection of the anodized implant surface.     

Adhesion to Er:YAG laser and bur prepared root and crown dentine

Background: The purpose of this study was to evaluate the bond strengths between dentine and resin composite obtained after Er:YAG laser treatment of crown or root dentine used together with self‐etch and total‐etch adhesive systems. Methods: One etch‐and‐rinse adhesive (Single Bond, 3M, USA) and one self‐etch system (Clearfil SE Bond, Kuraray, Japan) were applied to root and crown dentine prepared with a regular bur in a turbine or with an Er:YAG laser. The shear bond strength was determined after thermocycling and statistically analysed using independent t‐tests. Results: Crown sites bonded using Clearfil SE Bond and Single Bond adhesives yielded bond strengths similar to that of root dentine sites (p > 0.05). Clearfil SE Bond was stronger in both the lased and non‐lased groups (p < 0.05). The lowest bond strength was obtained when Single Bond without acid etching was used on Er:YAG ablated dentine. When total‐etch adhesive was used, there were significant differences (p < 0.05) between the laser‐ablated and laser‐ablated/acid‐etched and bur‐cut/acid‐etched groups. Conclusions: Er:YAG laser irradiation of root and crown dentine conducted prior to the adhesive protocol adversely affected adhesion and decreased bond strength compared with traditional preparation.     

Erbium:YAG laser application in caries therapy. Evaluation of patient perception and acceptance

Objectives: In previous studies it has been demonstrated that the Er:YAG laser can be used to prepare cavities efficiently and without thermal damage to the adjacent dental hard and soft tissues. To investigate the patients' response to Er:YAG laser preparation of teeth, a prospective clinical study was performed in five dental hospitals.

Methods: To evaluate patients' perception and response to cavity preparation a direct comparison was made between conventional mechanical preparation and Er:YAG laser preparation of caries in dental hard tissues. Half of the preparations were completed by the laser alone with standardized parameters, with the other half being mechanically prepared. The sequential order of treatment was randomized, and clinical parameters such as depth and location of the cavities were carefully balanced. A three-score evaluation scheme of patient responses was used: comfortable, uncomfortable, very uncomfortable. In addition the patients were asked to decide which was the more uncomfortable form of treatment and the preferred treatment for future caries therapy.

Results: The study included 103 patients with 206 preparations distributed amongst 194 teeth. All teeth gave vital responses (ice test) before and after both types of treatment. The laser treatment was found to be more comfortable than the mechanical treatment, with high statistical significance. During treatment, the need for local anaesthesia was 11% for mechanical preparation compared to 6% during laser application. It was found that 80% of the patients rated the conventional preparation as more uncomfortable than the laser treatment and 82% of the patients indicated that they would prefer the Er:YAG laser preparation for further caries treatment.

Conclusions: The application of the Er:YAG laser system is a more comfortable alternative or adjunctive method to conventional mechanical cavity preparation.