Influence of different surface treatments on bond strength of a Self-Adhesive resin cement to CAD-CAM materials / Influencia de los diferentes tratamientos superficiales en la unión del cemento resinoso autoadhesivo a los materiales CAD-CAM

To evaluate the shear bond strength (SBS) of self-adhesive resin cement when used with two different computer-aided design (CAD)-computer-aided manufacturing (CAM) materials after various surface treatments. Nanoceramic resin Lava Ultimate (LU) and feldspathic ceramic Vita Mark II (VM) CAD-CAM block samples were prepared with 1.5-mm thickness, and a total of 90 samples were obtained (N=90), with five samples of each block. The samples were divided into the following five groups according to the surface treatments (n=9): group 1, untreated (control); group 2,5% hydrofluoric acid etching; group 3, Er: YAG laser irradiation; group 4, tribochemical silica coating (Cojet); and group 5, air-abrasion with Al2O3. After silane application, resin cement was applied on a transparent matrix (diameter, 3mm; height, 2mm) on the blocks. SBS was determined using a universal testing device at a crosshead speed of 1mm/min. Two-way analysis of variance (ANOVA) and Tukey's post hoc tests were used to analyze the SBS values. LU showed the highest SBS value in group 4. The average SBS values in groups 3 and were found to be lower than that in the control group (p<0.05). When VM was examined, while all surface treatments increased the SBS values significantly, the highest SBS value was observed in group 4 (p<0.05). This study revealed that all surface treatments used negatively affected the bond strength values of self-adhesive resin cement to LU, except for Cojet application. The SBS values of resin cement with VM increased in all surface treatment application groups.

Evaluar la resistencia de unión al corte (SBS) del cemento de resina autoadhesivo cuando se utiliza con dos materiales diferentes de diseño asistido por computadora (CAD) y fabricación asistida por computadora (CAM) después de varios tratamientos superficiales. Se prepararon muestras de bloques CAD-CAM de resina Lava Ultimate (LU) y cerámica feldespática Vita Mark II (VM) con un espesor de 1,5mm, y se obtuvieron un total de 90 muestras (N=90), con cinco muestras de cada bloque. Las muestras se dividieron en los siguientes cinco grupos según los tratamientos superficiales (n=9): grupo 1, sin tratar (control); grupo 2, grabado con ácido fluorhídrico al 5%; grupo 3, irradiación con láser Er: YAG; grupo 4, recubrimiento triboquímico de sílice (Cojet); y grupo 5, aire-abrasión con Al2O3. Después de la aplicación de silano, se aplicó cemento de resina sobre una matriz transparente (diámetro, 3mm; altura, 2mm) sobre los bloques. La SBS se determinó usando un dispositivo de prueba universal a una velocidad de cruceta de 1mm/min. Se utilizaron análisis de varianza bidireccional (ANOVA) y pruebas post hoc de Tukey para analizar los valores de SBS. LU mostró el valor más alto de SBS en el grupo 4. Los valores promedio de SBS en los grupos 3 y fueron más bajos que en el grupo de control (p<0,05). Cuando se examinó VM, mientras que todos los tratamientos superficiales aumentaron significativamente los valores de SBS, el valor más alto de SBS se observó en el grupo 4 (p<0,05). Este estudio reveló que todos los tratamientos de superficie utilizados afectaron negativamente los valores de resistencia de la unión del cemento de resina autoadhesivo a LU, a excepción de la aplicación Cojet. Los valores de SBS del cemento de resina con VM aumentaron en todos los grupos de aplicación de tratamiento de superficie.

Effect of dual wavelength laser in the treatment of chronic periodontitis and the influence of cytokines in gingival crevicular fluid / 中国医师进修杂志

Objective:To investigate the clinical efficacy and prognostic factors of Neodymium doped: Yttrium Aluminum Garnet (Nd:YAG ) laser combined with Erbium:Yttrium Aluminum Garnet (Er:YAG) laser assisted subgingival scaling root planing (SRP) in the treatment of periodontitis.Methods:A prospective research method was adopted. A total of 66 patients with periodontitis treated in Hebei Chest Hospital from August 2018 to August 2020 were selected and divided into experimental group and control group according to the random number table method, with 33 cases in each group. The control group was treated with SRP, and the experimental group received Er:YAG laser curettage combined with root surface leveling on the basis of SRP, and irradiated the periodontal pocket with Nd:YAG laser. The changes of periodontal clinical indicators and cytokine levels in gingival crevicular fluid were examined before treatment, 4 weeks and 12 weeks after treatment. The patients were divided into PD<3 mm group and PD ≥ 3 mm group according to the probing depth (PD) of periodontal pocket after 12 weeks of treatment, the clinical data of the two groups were compared and analyzed, and the Logistic regression analysis was performed to analyze the risk factors affecting the prognosis of patients with periodontitis after laser treatment.Results:After 4 and 12 weeks of treatment, the PD, clinical attachment loss (CAL), sulcus bleeding index (SBI) and plaque index (PLI) of the two groups were significantly lower than those before treatment ( P<0.05), and the PD, CAL, SBI and PLI in experimental group were significantly lower than those in control group, after 4 weeks of treatment: (3.36 ± 0.21) mm vs. (3.91 ± 0.39) mm, (4.14 ± 0.67) mm vs. (4.75 ± 0.73) mm, (1.83 ± 0.20) scores vs. (2.58 ± 0.17) scores, (1.29 ± 0.24) scores vs. (1.61 ± 0.52) scores; after 12 weeks of treatment: (3.04 ± 0.28) mm vs. (3.66 ± 0.54) mm, (3.91 ± 0.47) mm vs. (4.68 ± 0.66) mm, (0.88 ± 0.06) scores vs. (1.35 ± 0.14) scores, (1.05 ± 0.31) scores vs. (1.57 ± 0.56) scores, the differences were statistically significant ( P<0.05). After 12 weeks of treatment, the levels of interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-8 (MMP-8) and interleukin-1β (IL-1β) in gingival crevicular fluid in experimental group were significantly decreased compared with those in control group: (2.95 ± 0.19) μg/L vs. (4.32 ± 0.84) μg/L, (2.63 ± 0.82) μg/L vs. (3.58 ± 0.51) μg/L, (12.42 ± 1.19) μg/L vs. (13.26 ± 0.68) μg/L, (4.15 ± 1.12) ng/L vs. (5.36 ± 0.42) ng/L, (2.65 ± 0.08) ng/L vs. (4.12 ± 0.19) ng/L, the differences were statistically significant ( P<0.05), while the level of transforming growth factor-β (TGF-β) was significantly increased compared with that in control group: (51.35 ± 8.95) ng/L vs. (44.90 ± 5.84) ng/L, and the differences between the groups were statistically significant ( P<0.05). Logistic regression analysis showed that the clinical indexes PD, SBI, PLI, IL-6, IL-8, TNF- α, MMP-8, IL-1β and crown root ratio of gingival crevicular fluid were all the risk factors for prognosis of periodontitis treated with dual wavelength laser ( P<0.05). Conclusions:Nd:YAG laser combined with Er:YAG laser assisted SRP can obtain good curative effect in the treatment of periodontitis. Periodontal clinical indexes PD, SBI, PLI, gingival crevicular fluid IL-6, IL-8 and TNF-α, MMP-8, IL-1β level and crown root ratio were independent risk factors for the prognosis of periodontitis treated with dual wavelength laser.

Comparison of four methods that remove calcium hydroxide from root canals / 口腔疾病防治

Objective@# To compare the efficiency of four methods that remove calcium hydroxide in root canals and to guide clinical practice. @* Methods @# Sixty-five isolated mandibular single root canal premolars were collected. After crown cutting and root canal preparation, a tooth was randomly selected as the blank control group, and the remaining 64 teeth were equally divided into Groups A and B (n = 32). Group A was injected with water-soluble calcium hydroxide, and Group B was injected with oil-soluble calcium hydroxide. After 2 weeks of drug sealing, Groups A and B were randomly divided into 4 groups (n = 8), including the lateral opening syringe group, sonic vibration group, ultrasonic group, and Er: YAG laser group. Before and after calcium hydroxide removal, the samples were scanned by cone-beam CT, and the data were imported into Mimics for 3D reconstruction. The root canal was divided into the following segments: superior root segment, middle and apical, and the calcium hydroxide volume of each segment of the root canal was calculated. The volumes of calcium hydroxide before and after removal were V1 and V2, respectively, with a clearance rate = (V1-V2)/V1×100%. Three-factor ANOVA was used for statistical analysis. After Groups A and B were reconstructed, the apical region with residual calcium hydroxide was selected, and the blank control was observed by scanning electron microscopy (SEM). @*Results @# Two types of calcium hydroxide could not be completely removed by the four flushing methods. The clearance rate of water-soluble calcium hydroxide was higher than that of oil-soluble calcium hydroxide (P<0.001). Among the three segments of the root canal, the clearance rate of the apical segment was lower (P<0.05). The Er: YAG laser treatment group showed the highest removal efficiency of two kinds of calcium hydroxide, which was higher than that of the other groups, especially in apical of the root. Compared with the sonic wave washing group and the syringe washing group, the ultrasonic wave washing group exhibited significant advantages (P<0.05). The clearance rate of the sonic wave washing group was higher in the oily calcium hydroxide root middle group than in the syringe washing group (P<0.05). SEM showed that the two kinds of calcium hydroxide could not be completely removed, but the residual rate of oil-soluble calcium hydroxide was large.@*Conclusion @# Both types of calcium hydroxide could not be completely removed, and compared to water-soluble calcium hydroxide, oil-soluble calcium hydroxide was more difficult to remove. Among the four cleaning methods, Er:YAG laser swing washing showed the higher cleaning efficiency.

The penetration effect of ultrasound and Er:YAG laser irrigation activation techniques on dentine of infected human root canals / 口腔疾病防治

Objective@#This ex vivo study evaluated the effect of ultrasound and Er:YAG laser irrigation activation techniques on the penetration of sodium hypochlorite solution into infected human root canal dentin, providing a reference for clinical infection control of infected root canals.@*Methods @#Thirty-six cases of infected root canals were collected and randomly divided into three groups according to the irrigation technique: 12 cases in the conventional syringe irrigation (CSI) group, 12 cases in the passive ultrasonic irrigation (PUI) group, 12 cases in the Er:YAG laser and photon-induced photoacoustic streaming (PIPS) group and 36 cases of clean root canals (12 cases in the CSI group, 12 cases in the PUI group, 12 cases in the PIPS group). All of the selected root canals were straight root canals of posterior teeth. After standardizing the root length, all canals were subjected to instrumentation and dynamic irrigation. 2% methylene blue solution was used to visualize the penetration of the irrigant. EXAKT cutting and grinding equipment was used to take transverse sections of 100-150 μm at the coronal, middle and apical thirds of the root canals. The data (maximum penetration depth, average penetration depth, and penetration percentage) were observed under a light microscope to evaluate the effect of dye penetration. @*Results @# With the three irrigation techniques, the maximum penetration depth, average penetration depth and penetration percentage of the infected root canals were significantly lower than those of clean root canals in the full length of the root canal (P<0.05). The penetration percentage, average penetration depth and maximum penetration depth of the PIPS group were significantly higher than those of the CSI group in the coronal, middle and apical thirds of the infected root canal, respectively (P<0.05). There was no significant difference in the maximum penetration depth, average penetration depth or penetration percentage between the PUI and CSI groups (P>0.05). There was also no significant difference in the maximum penetration depth, average penetration depth or penetration percentage between the PIPS and PUI groups (P>0.05). @*Conclusion @# The dentine permeability of infected root canals was weaker than that of clean root canals. Er:YAG laser-assisted irrigation activation technology could significantly improve the penetration of sodium hypochlorite solution into infected dentin, but passive ultrasonic irrigation did not significantly improve the penetration.

Effect of laser-assisted retrograde cavity preparation on push-out-bond-strength of mineral trioxide aggregate and calcium-enriched-mixture-cement / Efeito de preparo cavitário retrógrado assistido por laser na força de união de cimento de agregado trióxido mineral e cimento enriquecido com cálcio

Objective: This study aimed to determine the push-out-bond-strength(PBS) of mineral trioxide aggregate (BIOMTA+) and calcium-enriched-mixture-cement (CEM) in retrograde cavities prepared using Er: YAG laser and stainless-steel bur. Material and Methods: The root canals of 60 extracted single-rooted human teeth were prepared, filled and their apical portion of 3-mm were resected using a diamond bur and randomly divided into four groups according to technique of retrograde preparation and filling material as follows(n=15): Group1: bur/ BIOMTA+ ,Group2: bur/ CEM, Group3: Er:YAG laser/ BIOMTA+, Group4: Er:YAG laser/ CEM. PBS test were performed to specimens and failure modes were evaluated. The data were statistically analyzed with ANOVA, Post-Hoc Tukey and t tests (p< 0.05). Results: CEM was exhibited higher than bond strength compared to BIOMTA+ in retrograde cavity prepared using laser (p= 0.021) and BIOMTA+ in retrograde cavity prepared using bur was exhibited higher than bond strength compared to in retrograde cavities prepared using laser (p= 0.024). Failure modes were dominantly cohesive in all groups tested and one representative specimen each failure mode was examined in SEM and the general characteristics of the failure modes were confirmed. Conclusion: With in the limitations of the present study, when used CEM, Er: YAG laser-assisted retrograde cavity preparation positively affected the bond strength values compared to BIO MTA+. Considering its optimal adhesion, the calcium-enriched-mixture-cement (CEM) might be a good option as a filling material in retrograde cavities in clinical use. (AU)

Objetivo: O objetivo deste estudo foi determinar a força de união (PBS) de cimento de agregado trióxido mineral (BIO MTA+) e cimento enriquecido com cálcio (CEM) em preparos cavitários retrógrados realizados com: Laser Er-YAG e brocas de aço inoxidável. Material e Métodos: Canais radiculares de 60 dentes unirradiculares extraídos foram preparados, preenchidos e 3 mm de suas porções apicais foram ressecadas usando uma broca diamantada e divididos randomicamente em quatro grupos de acordo com a técnica de preparação retrógrada e o material de preenchimento (n=15): Grupo 1: Broca/BIO MTA+, Grupo 2: Broca/CEM, Grupo 3: Laser Er-YAG/BIO MTA+, Grupo 4: Laser Er-YAG/CEM. O teste de PBS foi realizado para as amostras e os modelos de falha foram avaliados. Os dados foram analisados estatisticamente pelos testes de ANOVA, Post-Hoc Tukey e testes t (p< 0.05). Resultados: CEM apresentou maior força de união que BIO MTA+ em cavidades retrógradas preparadas com laser (p= 0.021) e BIO MTA+ em cavidades retrógradas preparadas com brocas apresentou maior força de união quando comparado à cavidades retrógradas preparadas com laser (p= 0.024). Os modelos de falha foram predominantemente coesos em todos os grupos testados e um espécime representativo de cada modelo de falha foi examinado em MEV e as características gerais dos modelos de falha foram confirmadas. Conclusão: Com as limitações do presente estudo, quando usou-se CEM, o preparo de cavidades retrógradas através de Laser Er-YAG afetou positivamente os valores da força de união quando comparados com BIO MTA+. Considerando sua ótima adesão, o cimento enriquecido com cálcio (CEM) pode ser uma boa opção como um material de preenchimento em cavidades retrógradas no uso clínico.

Avaliação clínica de restaurações Classe V em cavidades tratadas com o laser de Er: YAG associado ao uso de sistemas adesivos autocondicionantes / Clinical evaluation of Class V restorations in cavities treated with Er: YAG laser associated with the use of self-etching adhesive systems

O objetivo deste estudo clínico, controlado, randomizado, cego e prospectivo foi de avaliar a efetividade clínica de restaurações em lesões não cariosas (cavidades Classe V) realizadas em superfícies dentais pré-tratadas ou não com laser de Er:YAG e utilizando dois sistemas adesivos autocondicionantes. Este estudo foi realizado com um total de 91 lesões e divididas em 4 grupos (n = 23) :G1(FL): Sem pré-tratamento e utilizando o adesiso FL-Bond II/Shofu; G2 (CF): sem pré-tratamento e utilizando o adesivo Clearfil SE Bond 2/Kuraray Noritake; G3 (Laser + FL): pré-tratamento associado ao uso do FL-Bond II/Shofu e G4 (Laser + CF): pré-tratamento associado ao uso do Clearfil SE Bond 2/Kuraray Noritake Os dentes avaliados foram os pré-molares de ambas as arcadas. A avaliação foi feita imediatamente após o tratamento e ao longo do tempo, em 3, 6 e 12 meses após a finalização da restauração. Para a avaliação da sensibilidade foi considerado a EVA (Escala Visual Analógica) e para a qualidade da restauração o método do USPHS modificado, considerando a avaliação de perda de retenção, integridade marginal, pigmentação marginal, presença de lesão de cárie em margem de restauração, vitalidade pulpar e sensibilidade pós-operatória. Os dados foram registrados em tabelas de frequência, e os escores transformados em postos para a aplicação do teste ANOVA. A significância estatística foi considerada para valores de p<0,05. Para os resultados da avaliação de sensibilidade houve uma diferença estatística significante da sensibilidade ao longo do tempo (p<0,001), sendo que essa diferença se deu a partir da avaliação T1 (48 horas) em todos os grupos. Em relação aos critérios avaliados no USPHS, foram encontrados variações estatísticas em alguns tópicos: Pigmentação marginal - G1 (FL) (p=0,041) e G2 ( Laser + FL) (p=0,009) e Integridade marginal G1(FL)( p=0,036). Os demais grupos e critérios não apresentaram variações estatísticas significantes.Pré-tratamentos com laser Er:YAG podem ser uma alternativa viável em restaurações adesivas do tipo classe V; no entanto, nenhum efeito sinérgico de ambos os tratamentos combinados foi observado.

The objective of this clinical, controlled, randomized, blinded and prospective study was to evaluate the clinical effectiveness of restorations in non-carious lesions (Class V cavities) performed on dental surfaces pre-treated or not with Er:YAG laser and using two adhesive systems self-conditioning. This study was carried out with a total of 91 lesions and divided into 4 groups (n = 23) :G1(FL): No pre-treatment and using the FL-Bond II/Shofu adhesive; G2 (CF): without pre-treatment and using Clearfil SE Bond 2/Kuraray Noritake adhesive; G3 (Laser + FL): pre-treatment associated with the use of FL-Bond II/Shofu and G4 (Laser + CF): pre-treatment associated with the use of Clearfil SE Bond 2/Kuraray Noritake The teeth evaluated were the premolars of both arcades. Assessment was performed immediately after treatment and over time, at 3, 6, and 12 months after completion of the restoration. The VAS (Visual Analogue Scale) was used for the sensitivity assessment and the modified USPHS method for the quality of the restoration, considering the assessment of loss of retention, marginal integrity, marginal pigmentation, presence of caries in the restoration margin. , pulp vitality and postoperative sensitivity. Data were recorded in frequency tables, and the scores were transformed into ranks for the application of the ANOVA test. Statistical significance was considered for values of p<0.05. For the results of the sensitivity evaluation, there was a statistically significant difference in sensitivity over time (p<0.001), and this difference occurred from the T1 evaluation (48 hours) in all groups. Regarding the criteria evaluated at the USPHS, statistical variations were found in some topics: Marginal pigmentation - G1 (FL) (p=0.041) and G2 (Laser + FL) (p=0.009) and Marginal integrity - G1(FL)( p =0.036). The other groups and criteria did not present significant statistical variations. Pretreatments with Er:YAG laser can be a viable alternative in class V adhesive restorations; however, no synergistic effect of both treatments combined was observed.

Erbium laser in the debonding of ceramics: a literature review / Laser de érbio na remoção de cerâmicas: uma revisão de literatura

Background: The debonding of crowns and ceramic veneers with laser is already a reality in the clinic. It presents benefits in comparison to traditional removal with the use of a rotating instrument; however, there is still no consolidated protocol and many professionals use it without the necessary scientific basis. Objective: The aim of this work was to perform a literature review on the debonding of indirect ceramic restorations using the Er:YAG and Er,Cr:YSGG lasers to provide clinical professionals and the scientific community a careful analysis, and also to guiding the use of irradiation at laser for such procedures. Methods: Bibliographic searches were performed in the following databases: Pubmed, Web of Science and Google Scholar. According to the inclusion criteria adopted, twenty-seven clinical and in vitro studies were selected in the period from 2007 to 2021. In the present work, the composition of the crowns and facets, as well as the types of cement and the laser irradiation protocols adopted in the selected studies is detailed. Conclusions: It was concluded that the use of erbium lasers for debonding of indirect ceramic restorations proved to be more selective and conservative when compared to removal with a rotary diamond instrument. Furthermore, it was shown to be in more efficient in debonding different types of ceramics. However, there are great variations in the "debonding" protocols, which emphasizes the need for further studies that seek to standardize the irradiation protocols considering the different clinical situations (AU)

Antecedentes: A remoção de coroas e facetas cerâmicas com laser já é uma realidade clínica e apresenta benefícios em relação à remoção tradicional com uso de instrumento rotatório diamantado; entretanto, ainda não existe um protocolo consolidado e muitos profissionais o utilizam sem o embasamento científico necessário. Objetivos: O objetivo deste trabalho foi realizar uma revisão da literatura sobre a remoção de restaurações cerâmicas indiretas utilizando os lasers Er:YAG e Er,Cr:YSGG para fornecer uma análise cuidadosa aos profissionais clínicos e à comunidade científica, além de orientar o uso da irradiação a laser para tal aplicação. Métodos: As buscas bibliográficas foram realizadas, nas seguintes bases de dados: Pubmed, Web of Science e Google Scholar. De acordo com os critérios de inclusão adotados, foram selecionados vinte e sete estudos clínicos e in vitro no período de 2007 a 2021. No presente trabalho, a composição das coroas e facetas, bem como os tipos de cimento e os protocolos de irradiação laser adotados nos estudos selecionados foram detalhados. Conclusão: Concluiu-se que o uso dos lasers de érbio para remoção de restaurações cerâmicas indiretas mostrou-se mais seletivo e conservador quando comparado à remoção com instrumento rotatório diamantado, além de ser eficiente na remoção de diferentes tipos de cerâmicas. No entanto, existem grandes variações nos protocolos de "debonding", o que enfatiza a necessidade de novos estudos que busquem uma padronização dos protocolos de irradiação considerando as diferentes situações clínicas.(AU)

Research progress on diagnosis and treatment of gingival pigmentation / 口腔疾病防治

@#Gingival pigmentation(GP) manifests as dark pigmentation spots, such as black or brown spots, in the gums. It is mostly caused by the deposition of melanin particles secreted by melanocytes on the gingival epithelium. The influencing factors may be divided into two categories, exogenous and endogenous. Exogenous factors include heavy metals, tattoos, smoking or drug use, and endogenous factors are related to certain diseases. The clinical grading of GP helps make a reasonable assessment of the necessity of treatment and prognosis. The Dummett-Gupta oral pigmentation index is a commonly used grading method, and the new grading method formed by combining the etiology and clinical manifestations described the patient’s situation more comprehensively. It is necessary to ask for a detailed medical history, complete examination, and correctly differentiate between physiological GP and GP caused by pathological state. Laser treatment is the currenttreatment with a better treatment effect and higher patient acceptance, and it is more comfortable and convenient, including diode laser, Er: YAG laser, and Nd: YAG laser, etc. This article summarizes the formation factors, clinical manifestations and treatment methods of GP to provide ideas for the clinical diagnosis and treatment of GP.

Efficacy of 2 940 nm Er∶YAG laser combined with electronic injection of collagen in treatment of striae gravidarum / 中华医学美学美容杂志

Objective:To assess the efficacy and security of 2 940 nm Er∶YAG laser combined with electronic injection of collagen in treatment of striae gravidarum.Methods:The symmetrical spots on both sides of abdomen of 21 subjects with striae gravidarum were divided into treatment and control groups by simple randomization method in the Department of Burn and Plastic Surgery, 903 Hospital from November 2017 to May 2019. The treatment group were treated with 2 940 nm Er∶YAG laser combined with electronic injection of collagen every 2 months for 3 sessions, and control group were received 2 940 nm Er∶YAG laser combined with electronic injection of physiological saline. The total effective rate, satisfaction, striae width, histopathology, and the adverse reaction were evaluated at 6 months after treatment.Results:A total of 19 subjects completed the whole trail. The clinical effective rate of the treatment group was 89.47% and the control group was 68.42%. In the treatment group, 11 cases were satisfied with and 6 cases were very satisfied with treatment outcome. In the treatment group, 8 cases were satisfied with and 3 cases were very satisfied with treatment outcome. The difference of total effective rate and satisfaction was statistically significant ( χ2 was 3.91 and 5.54, P was 0.045 and 0.019). The maximum width decreased by (1.53±0.97) mm on treatment side, and (1.37±1.01) mm on control side. The difference of striae width was statistically significant. No adverse effect was observed on both sides. Conclusions:The combination of the 2 940 nm Er∶YAG laser with electronic injection of collagen for treatment of striae gravidarum is a safe and effective approach for improving of striae gravidarum.

Research progress on the application of Er: YAG laser removing all-ceramic restorations / 口腔疾病防治

@#All-ceramic restorations are widely used in oral restoration because of their beauty and high strength. Glass ceramics and zirconia all-ceramic materials are the two most widely used all-ceramic materials in the clinic. However, when all-ceramic restorations need to be removed due to marginal microleakage and secondary caries, its high strength and high bonding strength greatly increase the difficulty of removal. In recent years, clinicians have tried to use Er: YAG lasers to remove all-ceramic restorations. The Er: YAG laser can be safely and efficiently applied to the removal of glass restorations, and it can also play a role in thinner zirconia restorations. Various factors, such as the material and thickness of the all-ceramic restoration, the type of cement, and the laser power, can affect the speed of removal of the Er: YAG laser. However, the current research is limited to case reports and in vitro studies, lacking systematic clinical research. The specific mechanism of Er: YAG laser removal of all-ceramic restorations and the influence of laser frequency, adhesive type, and abutment on the removal speed need to be further demonstrated by follow-up research.

Randomized comparative study in the treatment of oral leucoplakia with laser and conventional surgery / Estudo comparativo randomizado no tratamento da leucoplasia oral com laser e cirurgia convencional

Objective: High-energy lasers are used as an alternative to surgical treatment of potentially malignant disorders in the oral cavity. The present article aims to make a prospective randomised comparative clinical assessment of the effect of laser surgery and conventional surgery in the treatment of oral leukoplakia (OL). Material and methods: In the study were included 89 patients with histologically confirmed oral leukoplakia lesions. Laser excision of the lesions using Er YAG laser was performed in 36 of the patients, while standard surgical excision was used in 53 of the cases. Following clinical assessment comparing the two treatment methods was conducted based on: pain, wound healing, infection and recurrence of the lesions. Results: A statistically significant difference between two groups according pain in the postoperative period was found. Patients treated with laser ablation experienced far less pain than those treated with surgical excision. The healing time was significantly faster in the group treated with Er YAG laser, and regarding the occurrence of postoperative infections, the results of the two methods did not differ significantly. Recurrence was observed earlier in the group treated with laser ablation, but the levels align over a longer period of time. Conclusion: Er YAG laser ablation is a contemporary method for the treatment of oral leukoplakia without dysplasia, providing similar success, compared to conventional surgical excision, with less postoperative discomfort for the patients. (AU)

Objetivo: Os lasers de alta potência são utilizados como alternativa ao tratamento cirúrgico de doenças potencialmente malignas da cavidade oral. O presente artigo tem como objetivo fazer uma avaliação clínica prospectiva e randomizada comparativa do efeito da cirurgia a laser e da cirurgia convencional no tratamento da leucoplasia oral (LO). Material e Métodos: No estudo foram incluídos 89 pacientes com lesões de leucoplasia oral confirmadas histologicamente. A excisão das lesões com laser Er YAG foi realizada em 36 dos pacientes, enquanto a excisão cirúrgica padrão foi utilizada em 53 dos casos. A avaliação clínica seguinte comparando os dois métodos de tratamento foi realizada com base em: dor, cicatrização da ferida, infecção e recorrência das lesões. Resultados: Foi encontrada diferença estatisticamente significante entre os dois grupos de acordo com a dor no pós-operatório. Os pacientes tratados com ablação a laser experimentaram muito menos dor do que aqueles tratados com excisão cirúrgica. O tempo de cicatrização foi significativamente mais rápido no grupo tratado com laser Er YAG e, em relação à ocorrência de infecções pós-operatórias, os resultados dos dois métodos não diferiram significativamente. A recorrência foi observada mais cedo no grupo tratado com ablação a laser, mas os níveis se alinham por um longo período de tempo. Conclusão: A ablação a laser Er YAG é um método contemporâneo para o tratamento da leucoplasia oral sem displasia, proporcionando sucesso semelhante ao da excisão cirúrgica convencional, com menor desconforto pós-operatório para os pacientes. (AU)

Dentinal tubule occlusion using Er:YAG Laser: an in vitro study

Abstract Objectives We analyzed the effects of the Er:YAG laser used with different parameters on dentinal tubule (DT) occlusion, intrapulpal temperature and pulp tissue morphology in order to determine the optimal parameters for treating dentin hypersensitivity. Methodology Dentin specimens prepared from 36 extracted human third molars were randomized into six groups according to the treatment method (n=6 each): control (A); Gluma desensitizer (B); and Er:YAG laser treatment at 0.5 W , 167 J/cm2 (50 mJ, 10 Hz) (C), 1 W , 334 J/cm2 (50 mJ, 20 Hz) (D), 2 W , 668 J/cm2 (100 mJ, 20 Hz) (E), and 4 W and 1336 J/cm2 (200 mJ, 20 Hz) (F). Treatment-induced morphological changes of the dentin surfaces were assessed using scanning electron microscopy (SEM) to find parameters showing optimal dentin tubule occluding efficacy. To further verify the safety of these parameters (0.5 W, 167 J/cm2), intrapulpal temperature changes were recorded during laser irradiation, and morphological alterations of the dental pulp tissue were observed with an upright microscope. Results Er:YAG laser irradiation at 0.5 W (167 J/cm2) were found to be superior in DT occlusion, with an exposure rate significantly lower than those in the other groups (P<0.05). Intrapulpal temperature changes induced by Er:YAG laser irradiation at 0.5 W (167 J/cm2) with (G) and without (H) water and air cooling were demonstrated to be below the threshold. Also, no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Conclusion Therefore, 0.5 W (167 J/cm2) is a suitable parameter for Er:YAG laser to occlude DTs, and it is safe to the pulp tissue.

Research progress on Er: YAG lasers applied for tooth bleaching / 口腔疾病防治

@#Er: YAG laser bleaching is a new tooth bleaching method compared with traditional bleaching technology. The Er: YAG laser significantly improves the bleaching efficiency, has the advantages of high safety, short treatment time and excellent bleaching effect and is widely used in clinical operations. This paper summarizes the working principle and bleaching characteristics of Er: YAG laser bleaching technology and its effect on tooth structure. The existing literature suggests that the high absorption of water and hydroxyapatite by the Er: YAG laser makes it work well on water-bearing tissues and dental tissues. When it is absorbed by the bleaching agent on the tooth surface, it accelerates the catalytic oxidation-reduction reaction and selectively acts on the pigment particles deposited on the tooth, thereby achieving the effect of tooth bleaching. Er: YAG laser bleaching can be applied to most discolored teeth. The bleaching process is rapid and effective. During the bleaching process, for the dental pulp tissue, the temperature of the pulp cavity is lower than the critical value of 5.6 ℃, causing no pathological damage to the dental pulp tissue. For the hard tissues of the teeth, laser irradiation will cause changes in the chemical composition of calcium and phosphorus. The enamel presents a unique lava-like shape, and the bonding strength of the tooth increases after bleaching. Compared with other lasers, the Er: YAG laser has a wavelength close to the peak of water, and adding other ingredients to the bleaching agent is not required. Almost all the energy is used for the bleaching agent, with no damage to the surrounding tissues.

Effects of desensitizer and laser desensitization on surface morphology, hardness and composition of dentin / 吉林大学学报(医学版)

Objective: To investigate the effects of Aominqing desensitizer and two laser (Er: YAG and Nd: YAG) treatments on the dentin surface morphology, hardness, and calcium (Ca) and phosphorus (P) contents and Ca/P ratio, to clarify the possible mechanisms, and to provide reference for its clinical application in the treatment of dentin sensitivity. Methods: The fresh third molars extracted because of impaction from the volunaeers aged 18-20 years old were collected. A total of 32 dentin slices of 2 mm were prepared; the samples were divided into blank control group, Aominqing group Er: YAG group and Nd: YAG group, and there were eight samples in each group. Except blank control group, the samples in other groups were used to establish the dentin hypersensitivity models by purifying the polluted layer with 17% EDTA. Each sample was cut by linear cutting machine from the middle symmetry into two semicircle dentin; the half was used to detect the dentin surface microhardness (SMH) values by microhardness meter, another half was used to observe the surface morphology and analyze the Ca and P contents with SEM and EDS was observed. Results: There were no significant differences in the SMH values of dentin samples between various groups (P>0.05). In blank control group, there was no smear layer on the dentin surface with wide tubules and smooth and clean surface; the dentin tubules of the samples in Aominqing group were partially closed, and obstructions were seen in the tubuless in Er: YAG group the dentin tubules were little or no open, most of them were partially or completely closed tubules, the surface had the melting changes in Nd: YAG group, the dentin tubules were partially or completely closed with few open tubules and the surface was molten. Compared with blank control group and Aominging group, the Ca and P contents in the samples in Er: YAG group and Nd: YAG were significantly increased; there was no statistically significant difference in the contents of Ca and P between and blank control group and Aclinsing group (P>0.05), and the difference between Er: YAG group and Nd: YAG group was not significant (P>0.05). The differences in the Ca/P ratios between various groups were not statistically significant (P>0.05). Conclusion: The application of Aominqing desensitization agent, Er: YAG laser and Nd: YAG laser can not cause the changes of dentin SMH and the Ca/P ratio, but the application of Er: YAG and Nd: YAG laser to dentin can significantly increase the contents of Ca and P and change the morphology, composition and structure of dentin surface.

Comparison of the effect and safety of Er:YAG laser combined with fluoride and methylene blue-photodynamic therapy on caries prevention / 华西口腔医学杂志

OBJECTIVE@#To compare the anti-caries effect and safety of Er:YAG laser combined with fluoride and methylene blue-photodynamic therapy (MB-PDT).@*METHODS@#A total of 28 rat dental caries models were established and randomly divided into seven groups: photodynamic therapy (PDT) group, laser combined with fluoride group, laser group, sodium fluoride group, and 0.9% saline control group. Spectrophotometric optical density was used to reflect the growth of Streptococcus mutans. Laser-induced fluorescence diagnostic (LF) instrument was utilized to detect the demineralization degree of dental caries. Histopathological sections were employed to observe the damage of dental pulp and buccal mucosa.@*RESULTS@#The optical density (OD) value of the PDT and combination groups was significantly lower than that of other treatment groups (P<0.05). An increase in LF value and demineralization occurred in varying degrees with different treatment methods. Histopathological observation showed that pulp and buccal mucosa injury was more obvious in the combination group of 70 mw·cm⁻² and Er:YAG laser group compared with other groups.@*CONCLUSIONS@#Under the same parameters, the combined group and PDT have good germicidal efficacy, but PDT has fewer adverse reactions and less damage. It is an effective and safe method for caries prevention.

Comparing the Effects of Er:Yag Laser and Bur on Tensile Bond Strength of Single Step Adhesive System At Different Dentin Depths – An In Vitro Study

The hard tissue erbium lasers have the capability to prepare enamel, dentin, caries, cementum and bone in addition to cutting soft tissue.The present study is aimed at evaluating the tensile bond strength a self etching restorative system, on superficial and deep dentin, after cutting the tooth with bur or Er:YAG laser. Methods: Sixty sound extracted human premolars were used in the study. These teeth were then randomly divided into two groups of thirty teeth each. Group 1- Bur cut, cut using diamond cutting disc and Group 2- Laser cut, cut using Er:YAG laser calibrated with 200mJ/10HZ/2.0W under 4ml/min water spray. These were then divided into two more subgroups of fifteen teeth as superficial and deep dentin sub groups. Specimens were coated with bonding agent followed by a microhybrid resin composite (SUREFILL,DENTSPLY). The specimens were then debonded in tension by mounting it on a universal testing machine (Instron Type 4204 Co.USA) and specimen SEM analysis of surfaces was done. Results: Bur cut superficial dentin showed maximum tensile bond strength (22.86 MPa) while bur cut deep dentin showed the least tensile bond strength (15.8MPa),Laser cut superficial dentin and deep dentin showed almost similar bond strength -19.18 MPa and 19.94MPa respectively. Conclusion: The superficial dentin produced better bond strength and results than deep dentin. Surface treatment by Er:YAG laser hampered the adhesion of self etching adhesive systems in both superficial and deep dentin.

Comparison of Shear Bond Strength of Occlusal Pad Debonding Pliers Before and After Er-YAG Laser Application: An In vitro Study

Background: Er-YAG laser showed to be effective in debonding ceramic bracket from the enamel surface. Until lately, no previous study was conducted to assess the outcome of the laser in debonding ceramic brackets from tooth surface comparing it with conventional occlusal pad debonding pliers. Materials and methods: Total 60 ceramic brackets were bonded on the tooth surface which was divided randomly into 2 groups. One was assigned as a control non-lased group and the other was experimental lased groups. Er-YAG laser irradiated the experimental groups at the power of 5 W for 10 seconds with swiping motion and 50% air-water cooling. In the lased experimental group, the laser was applied at energy of 250 mJ, 20 Hz frequency, and pulse duration of 100 μs. Results: Shear bond strengths and adhesive remnant index scores were statistically calculated. A highly significant difference of SBS between the non-lased control group and the lased experimental group was observed (p<0.000). A non-significant difference in ARI scores was observed when the non-lased control group was compared with the lased experimental group. Conclusion: It could be concluded that Er-YAG laser is effective in ceramic bracket debonding. This protocol promotes debonding without bracket fracture or enamel surface cracks or damage.

The applications of Nd：YAG laser and Er：YAG laser in endodontics / 口腔疾病防治

@#With the gradual maturity of laser technology, it has become widely considered a new method for disease treatment. Nd：YAG laser and Er：YAG laser are two representative solid-state lasers. These lasers are easy to use, comfortable and safe, and thus, they have recently become a research hotspot in dental treatment. Nd：YAG laser and Er：YAG laser have been used for the treatment of dentin hypersensitivity and dental caries, root canal therapy, pulp preservation and apical surgery. They are effective adjuvant methods for the treatment of dental pulp diseases and provide new avenues for clinical treatment. In this paper, the application of Nd：YAG laser and Er：YAG laser in the treatment of dental pulp disease is described to provide a reference for clinical treatment options.

Efficacy of removal of cariogenic bacteria and carious dentin by ablation using different modes of Er: YAG lasers

The primary objective of this in vitro study was to evaluate the efficiency of removal of cariogenic bacteria and carious dentin by ablation using two lasers: fluorescence-feedback controlled (FFC) Er:YAG laser and different pulses of Er:YAG laser based on variable square pulse technology (VSPt). The secondary objective was to measure the temperature during laser ablation of carious tissue. Seventy-two extracted human molars were used in this study. Sixty teeth with carious dentin were randomly divided into four experimental groups according to the treatment for caries removal: group 1: 400 µs (FFC group); group 2: super short pulse (SSP group, 50 µs pulse); group 3: medium short pulse (MSP group, 100 µs pulse); group 4: short pulse (SP group, 300 µs pulse) and one positive control group with no treatment. Twelve teeth without carious lesion were used as a negative control group. After caries removal, swabs were taken with cotton pellets and real-time PCR analysis was performed. During caries ablation, a thermal infrared camera was used to measure the temperature changes. In all experimental groups, specimens were free of bacterial contamination after the treatment. In the SSP, MSP and SP groups, temperatures measured during caries ablation were significantly higher compared to temperatures in the FFC group (P<0.001). In this in vitro study, laser treatment for removal of carious dentin and cariogenic bacteria was an efficient treatment modality without causing excessive temperatures that might adversely affect pulp vitality.

The effects of different Er: YAG laser parameters combined with dole fluorine on dentinal tubules / 口腔疾病防治

Objective@# To explore the effects of Er: YAG lasers with different pulse energies and of Er: YAG lasers combined with Duraphat on dentine surface morphology and the dentinal tubule exposure rate, thereby providing a theoretical basis and parameters for clinically treating dentine hypersensitivity with Er: YAG lasers.@*Methods @# Dentinal tubule exposure models were divided into five groups, namely, group A (single Er: YAG laser exposure), group B (Duraphat+ Er: YAG laser), and group C (Er: YAG laser+Duraphat), which were exposed to 6 levels of pulse energy (80 mJ/P- 250 mJ/P), and experimental control group D (Duraphat group) and blank control group E. Scanning electron microscopy was used to observe dentine surface morphology and dentinal tubule closure in these groups, and Image-Pro Plus 6.0 software was used for image analysis to measure the exposure rates of the five groups of dentinal tubules.@*Results@#The dentinal tubule exposure rates for the A-D groups were significantly lower than that of the E group (P < 0.001); when the Er: YAG laser pulse energy was less than 250 mJ/P, the dentinal tubule exposure rates for the A-C groups were all lower than that of the D group, but when the pulse energy was higher than 250 mJ/P, the dentinal tubule exposure rates for the A-C groups were higher than that of the D group, showing significant differences (P < 0.001); under the same handling method, when the pulse energy was 80~200 mJ/P, the dentinal tubule exposure rate decreased as the pulse energy increased. If the pulse energy reached 250 mJ/P, the exposure rate of the dentinal tubules increased instead. There were apparently no significant differences between 80 mJ/P, 100 mJ/P, 160 mJ/P and 200 mJ/P in the A and C groups or between 80 mJ/P and 100 mJ/P in the B group (P > 0.05), while significant differences existed among the other groups (P< 0.05). Under the same pulse energy, the dentinal tubule exposure rates were A group > C group >B group; under different pulse energies, there existed significant differences between the A and B groups (P < 0.05); when the pulse energy was 120~250 mJ/P, there were significant differences between the B and C groups (P < 0.05), while there were no significant differences among other groups (P＜0.05).@*Conclusion@#Er: YAG lasers can close the dentinal tubules and play a cooperative role if combined with Duraphat; the effects of laser exposure are better if fluorine is applied beforehand; and dentinal tubule closure is positively correlated with the pulse energy of Er: YAG lasers within a certain energy scope, but when the pulse energy reaches 200 mJ/P, the dentine surface is excessively fused and injured.