Efeito de doses terapêuticas de radioterapia sobre a morfologia, composição química e microdureza do esmalte e da dentina de dentes permanentes / Effect of therapeutic doses of radiotherapy on the morphology, chemical composition, and microhardness of enamel and dentin of permanent teeth

Introdução: Padrões atípicos de cárie dentária em pacientes submetidos a radioterapia para o tratamento do câncer de cabeça e pescoço podem estar associados aos efeitos da radiação sobre as glândulas salivares e tecidos dentários duros. Somados, podem contribuir para a cárie relacionada a radiação. Embora haja evidências sobre alterações sofridas pelos tecidos dentários duros após radioterapia, não há consenso na literatura sobre a gravidade destas alterações. Objetivo: avaliar a microestrutura, composição química e microdureza do esmalte e da dentina de dentes permanentes submetidos a doses terapêuticas de radioterapia in vitro. Material e métodos: estudo experimental, qualitativo, quantitativo e semiquantitativo. Foram obtidos fragmentos coronários de 24 terceiros molares. Constituiuse 2 grupos: NIR (controle): formado por fragmentos de dentes não irradiados e IVT (irradiado): formado por fragmentos de dentes irradiados in vitro (2 Gy/dia 5 vezes por semana, totalizando 70 Gy). Os fragmentos foram submetidos a análise da microdureza (n=24), Espectroscopia de Infravermelho com Transformada de Fourier (FTIR) (n=24), análise morfológica através de Microscopia Eletrônica de Varredura (MEV) (n=19) e análise de elementos químicos por Espectroscopia de Dispersão de Energia de Raio X (EDX) (n=19). As análises foram feitas antes e após a irradiação. Os dados foram testados para distribuição normal (teste de Shapiro-Wilk, α = 0,05) e igualdade de variâncias (teste de Levene, α = 0,05), seguido de testes estatísticos paramétricos. Para a comparação das variáveis quantitativas foi aplicado o teste T de Student. Um valor de p <0,05 (5%) foi considerado estatisticamente significativo. Resultados: em relação as propriedades mecânicas observamos redução significativa da microdureza do esmalte e dentina após irradiação (p<0,001). A análise da composição química por FTIR mostrou que no esmalte não houve alteração da razão matriz/mineral (M:M) no grupo irradiado (p<0,821), mas houve redução significativa do teor relativo de carbonato (RCC) após irradiação (p<0,039). Na dentina observamos redução significativa da razão matriz/mineral (M:M) e carbonato/mineral (C:M) no grupo irradiado (p<0,001), enquanto a razão amida I/amida III, não sofreu alteração significativa após irradiação (p<0,536). Na análise de EDX realizadas no esmalte, não observamos variação no conteúdo de cálcio e fósforo após radiação, mas a razão Ca/P mostrou-se significantemente mais elevada no grupo irradiado (p<0,001). Na dentina, não houve alteração do teor de cálcio e fósforo, assim como da razão Ca/P após irradiação (p<0,267). A análise morfológica através de MEV pós irradiação, mostrou que no esmalte a maioria das amostras apresentaram uma alteração das características microestruturais com a presença de microporosidades, perda de padrões regulares das áreas prismáticas e interprismáticas e presença de áreas amorfas. Na dentina observamos manutenção do padrão de dentina peritubular e intertubular, com a presença de túbulos dentinários desobliterados e com a rede de fibras colágenas mais evidente grupo irradiado. Conclusão: as doses terapêuticas de radioterapia provocaram redução da microdureza, alterações na microestrutura e composição química do esmalte e da dentina. Assim, inferimos que doses terapêuticas de radiação exercem um impacto negativo sobre as propriedades mecânicas, químicas e micro-morfológicas dos tecidos dentários duros aumentando a vulnerabilidade destes tecidos à cárie relacionada a radiação.

INTRODUCTION: Atypical patterns of dental caries in patients undergoing radiotherapy to treat head and neck cancer may be associated with the effects of radiation on salivary glands and dental hard tissues. Together, they can contribute to radiation-related caries. Although there is evidence of changes in hard dental tissues after radiotherapy, there is no agreement in the literature on the severity of these changes. PURPOSE: This study aims to evaluate the microstructure, chemical composition, and microhardness of enamel and dentin in permanent teeth subject to therapeutic doses of in vitro radiotherapy. MATERIAL AND METHODS: This is an experimental, qualitative, quantitative, and semi-quantitative study. Coronary fragments were obtained from 24 third molars. Two groups were created: NIR (control), including fragments of non-irradiated teeth, and IVT (irradiated), including fragments of in vitro irradiated teeth (2Gy/day five times a week, totaling 70Gy). The fragments underwent microhardness analysis (n =24), Fourier-transform Infrared Spectroscopy (FTIR) (n=24), morphological analysis by Scanning Electron Microscope (SEM) (n=19), and analysis of chemical elements by Energy-dispersive X-Ray Spectroscopy (EDX) (n=19). The analyses were performed before and after irradiation. Data were tested for normal distribution (ShapiroWilk test, α = 0.05) and equality of variances (Levene test, α = 0.05), followed by parametric statistical tests. The Student's T test was applied to compare the quantitative variables. A pvalue < 0.05 (5%) was considered statistically significant. RESULTS: Concerning the mechanical properties, we observed a significant reduction in enamel and dentin microhardness after irradiation (p<0.001). The analysis of the chemical composition by FTIR showed no change in the mineral/matrix ratio (M:M) in enamel in the irradiated group (p<0.821), but there was a significant reduction in the relative carbonate content (RCC) after irradiation (p<0.039). In dentin, we observed a significant reduction in the mineral/matrix ratio (M:M) and carbonate/mineral ratio (C:M) in the irradiated group (p<0.001). In contrast, the amide I/amide III ratio showed no significant change after irradiation (p<0.536). In the EDX analysis performed on enamel, we did not observe any calcium and phosphorus content variation after radiation. However, the Ca/P ratio was significantly higher in the irradiated group (p<0.001). In dentin, there was no change either in calcium and phosphorus contents or in the Ca/P ratio after irradiation (p<0.267). The morphological analysis through SEM after irradiation showed that there is a loss in the characteristics of the enamel surface of most fragments, with the presence of microporosities, loss of regular patterns of the prismatic and interprismatic areas, and the presence of amorphous areas. In dentin, we observed maintenance of the peritubular and intertubular dentin patterns, with the presence of unobliterated dentinal tubules and with the most evident network of collagen fibers in the irradiated group. CONCLUSION: Therapeutic doses of radiotherapy caused a reduction in microhardness and changes in the microstructure and chemical composition of enamel and dentin. Thus, we conclude that therapeutic doses of radiation have a negative impact on the mechanical, chemical, and micromorphological properties of hard dental tissues, increasing the vulnerability of these tissues to radiation-related caries

Effect of violet LED light on in-office bleaching protocols: a randomized controlled clinical trial

Abstract Objective This study evaluated the clinical effect of violet LED light on in-office bleaching used alone or combined with 37% carbamide peroxide (CP) or 35% hydrogen peroxide (HP). Methodology A total of 100 patients were divided into five groups (n=20): LED, LED/CP, CP, LED/HP and HP. Colorimetric evaluation was performed using a spectrophotometer (ΔE, ΔL, Δa, Δb) and a visual shade guide (ΔSGU). Calcium (Ca)/phosphorous (P) ratio was quantified in the enamel microbiopsies. Measurements were performed at baseline (T 0 ), after bleaching (T B ) and in the 14-day follow-up (T 14 ). At each bleaching session, a visual scale determined the absolute risk (AR) and intensity of tooth sensitivity (TS). Data were evaluated by one-way (ΔE, Δa, ΔL, Δb), two-way repeated measures ANOVA (Ca/P ratio), and Tukey post-hoc tests. ΔSGU and TS were evaluated by Kruskal-Wallis and Mann-Whitney, and AR by Chi-Squared tests (a=5%). Results LED produced the lowest ΔE (p<0.05), but LED/HP promoted greater ΔE, ΔSGU and Δb (T 14 ) than HP (p<0.05). No differences were observed in ΔE and ΔSGU for LED/CP and HP groups (p>0.05). ΔL and Δa were not influenced by LED activation. After bleaching, LED/CP exhibited greater Δb than CP (p>0.05), but no differences were found between these groups at T 14 (p>0.05). LED treatment promoted the lowest risk of TS (16%), while HP promoted the highest (94.4%) (p<0.05). No statistical differences of risk of TS were found for CP (44%), LED/CP (61%) and LED/HP (88%) groups (p>0.05). No differences were found in enamel Ca/P ratio among treatments, regardless of evaluation times. Conclusions Violet LED alone produced the lowest bleaching effect, but enhanced HP bleaching results. Patients treated with LED/CP reached the same efficacy of HP, with reduced risk and intensity of tooth sensitivity and none of the bleaching protocols adversely affected enamel mineral content.

The contribution of ceramic thickness and adhesive type on the de-bonding strength of dental ceramic veneers using Er, Cr: YSGG laser / La contribución del espesor de la cerámica y el tipo de adhesivo a la resistencia de desunión de las carillas dentales de cerámica con láser Er, Cr: YSGG

Purpose: De-bonding strength of ceramic veneers by laser use needs to be evaluated in detail. The aim of this study, is to determine the contribution of ceramic thickness and cementing agents to the de-bonding strength of ceramic veneers using Er,Cr:YSGG laser. Methods: A total of 120 maxillary central incisors specimens were randomly divided into twelve groups on the basis of disc thickness, cementing agent, and Er,Cr:YSGG laser use. Under laboratory conditions, 120 IPS Empress II system discs 0.5mm, 1mm, and 2mm in thickness were applied to the tooth surfaces, for laser use. An Er,Cr:YSGG laser system was applied to the central surface of the IPS Empress II discs on specimens in all laser groups (Groups 1,3,5,7,9,11). Then the shear bond strength (SBS) for all specimens were tested with a testing machine at a speed of 0.5mm/min. The SBS values were considered as the de-bonding strength. Results: The mean de-bonding strength values for Groups 9 and 11 (0,5 mm disc thickness + laser application) have the lowest median load (0.000 N), while Group 4 (2mm disc thickness + no laser) has the highest median load (573.885 N). The de-bonding strengths of all the groups without laser application were higher than those of all groups with laser use. When laser is applied, the mean de-bonding strength decreases with decreasing disc thickness, and it reaches zero at 0.5mm thickness of discs cemented by self- or total-etch adhesives. Conclusions: The de-bonding strength decreases with laser use, and decreasing disc thickness. In the absence of laser, the mean de-bonding values of discs cemented by a total etch adhesive system are always higher than those of discs cemented with a self-etch adhesive system. Without any extra load, all 0.5mm thick discs were dislodged from teeth while applying or testing the laser.

Propósito: La resistencia de desunión de las carillas de cerámica mediante el uso del láser debe evaluarse en detalle. El objetivo de este estudio es determinar la contribución del espesor de la cerámica y los agentes de cementación a la resistencia de desunión de las carillas de cerámica utilizando el láser Er, Cr: YSGG. Métodos: Un total de 120 incisivos centrales maxilares se dividieron al azar en doce grupos según el grosor del disco, el agente de cementación y el uso del láser Er, Cr: YSGG. En condiciones de laboratorio, se aplicaron en las superficies de los dientes 120 discos del sistema IPS Empress II de 0,5mm, 1mm y 2mm de grosor, para uso con láser. Se aplicó un sistema láser Er, Cr: YSGG a la superficie central de los discos IPS Empress II en muestras de todos los grupos de láser (Grupos 1,3,5,7,9,11). Luego, la resistencia de la unión al cizallamiento (SBS) para todas las muestras se probó con una máquina de prueba a una velocidad de 0.5mm/min. Los valores de SBS se consideraron como la fuerza de desunión. Resultados: Los valores medios de resistencia de desunión para los Grupos 9 y 11 (espesor de disco de 0,5mm + aplicación de láser) demostró la carga media más baja (0,000 N), mientras que el Grupo 4 (espesor de disco de 2 mm + sin láser) tuvo la carga media más alta (573.885 N). Las fuerzas de desunión de todos los grupos sin aplicación de láser fueron superiores a las de todos los grupos con uso de láser. Cuando se aplica el láser, la fuerza media de desunión disminuye al disminuir el grosor del disco, y llega a cero con el grosor de 0,5mm de los discos cementados, para ambos adhesivos de grabado. Conclusiones: la fuerza de desunión disminuye con el uso del láser y disminuye con el grosor del disco. En ausencia de láser, los valores medios de desunión de los discos cementados con un sistema de adhesivo de grabado total son siempre más altos que los de los discos cementados con un sistema de adhesivo de autograbado. Sin ninguna carga adicional, todos los discos de 0,5mm de grosor se desprendieron de los dientes al aplicar el láser.

Microhardness and Ultrastructure of Demineralized Gamma-Irradiated Human Enamel after Diode Laser (980 nm) and Fluoride Surface Treatment

Abstract Quality of life drastically diminished after radiotherapy due to radiation induced oral complications. Fluoride was found to be helpful in decreasing the incidence of radiation caries; however it has not led to elimination of dental caries. Thus, new techniques containing low fluoride concentration or not containing fluoride at all, as laser irradiation, have been studied to prevent the beginning or progression of caries. So the purpose of this study is to investigate the effect of laser surface treatment with or without fluoride on microhardness and ultrastructure of demineralized gamma irradiated enamel; Thirty enamel slabs were allocated into three groups (n=10): G slabs were subjected to gamma irradiation only; GL slabs were subjected to gamma irradiation followed by diode laser and GFL slabs were subjected to gamma irradiation followed by fluoride then diode laser. Slabs were then exposed to demineralizing solution for 72 hours. Examination of slabs was performed using vickers microhardness test and scanning electron microscope; The lowest microhardness was recorded in group G, while inGL and GFL groups it significantly increased. Scanning electron microscope revealed a pronounced loss of central prism core and retention of prism peripheries in group G. Confluence of prismatic and interprismatic structures in GL slabs and irregular rough surface with prismatic boundaries conservation in GFL slabs were detected. Applying laser improved the microhardness and counteracted the adverse effect of gamma radiation. Adding fluoride before laser irradiation had a marked effect on microhardness..

Effect of fluoride application during radiotherapy on enamel demineralization

Abstract Radiation-related caries are one the most undesired reactions manifested during or after head and neck radiotherapy. Fluoride application is an important strategy to reduce demineralization and enhance remineralizaton. Objective: To evaluate the effect of the topical application of fluoride during irradiation on dental enamel demineralization. Material and Methods: Thirty molars were randomly divided into three groups: Non-irradiated (NI), Irradiated (I), Irradiated with fluoride (IF). Each group was subdivided according to the presence or absence of pH-cycling (n=5). In the irradiated groups, the teeth received 70 Gy. The enamel's chemical composition was measured using Fourier Transform Infrared Spectrometry (organic matrix/mineral ratio - M/M and relative carbonate content - RCC). Vickers microhardness (VHN) and elastic modulus (E) were evaluated at three depths (surface, middle and deep enamel). Scanning electron microscopy (SEM) was used to assess the enamel's morphology. Results: The FTIR analysis (M/M and RCC) showed significant differences for irradiation, pH-cycling and the interaction between factors (p<0.001). Without pH-cycling, IF had the lowest organic matrix/mineral ratio and relative carbonate content. With pH-cycling, the organic matrix/mineral ratio increased and the relative carbonate content decreased, except for IF. VHN was influenced only by pH-cycling (p<0.001), which generated higher VHN values. ANOVA detected significant differences in E for irradiation (p<0.001), pH-cycling (p<0.001) and for the interaction between irradiation and pH-cycling (p<0.001). Increased E was found for group I without pH-cycling. With pH-cycling, groups I and IF were similar, and showed higher values than NI. The SEM images showed no morphological changes without pH-cycling. With pH-cycling, fluoride helped to maintain the outer enamel's morphology. Conclusions: Fluoride reduced mineral loss and maintained the outer morphology of irradiated and cycled enamel. However, it was not as effective in preserving the mechanical properties of enamel. Radiotherapy altered the enamel's elastic modulus and its chemical composition.

Using UV light for adhesive remnant removal after debonding of orthodontic accessories

Abstract The objective of this study was to assess the effect of a UV light-based auxiliary illumination on adhesive remnant (AR) removal after orthodontic debonding. Sixty human molars were divided according to the adhesive used for bonding: O-opaque; LF-low fluorescence; and HF-high fluorescence. After debonding, the teeth were subdivided according to the AR removal method: No UV light or With UV light. After AR removal, the teeth were polished. Direct visual analysis, scanning electron microscopy (SEM) and time quantification for AR removal analyses were performed (Fisher-Freeman-Halton, Fisher's exact, chi-square trend, ANOVA, and independent t-tests; α = 5%). Concerning the adhesives, there was no significant difference among direct visual, SEM and time analyses for AR removal (p ≥ 0.05). Regarding AR removal methods, a similarity among the subgroups was verified for direct visual and SEM analyses (p≥0.05). However, a significant trend was verified for the with UV light method to produce greater marks, and the no UV light method, to produce a greater rate of samples with AR before polishing (p = 0.015). AR removal with light was significantly quicker in comparison with the no UV light method (p < 0.0001). The use of UV light may aid orthodontists in removing AR more thoroughly and in less time. However, they should receive special training to apply this technology, and should never dismiss the final polishing procedure.

Non-contact profilometry of eroded and abraded enamel irradiated with an Er: YAG laser

Abstract Literature has reported positive results regarding the use of lasers in the control of erosive lesions; however, evaluating whether they are effective in the control of the progression of erosive/abrasive lesions is important. Objectives This study aimed to evaluate the effect of the Er:YAG laser irradiation in controlling the progression of erosion associated with abrasive lesions in enamel. Material and methods Bovine incisors were sectioned, flattened and polished. Forty-eight enamel slabs were subjected to treatment in an intraoral phase. Twelve volunteers used an intraoral appliance containing one slab that was irradiated with an Er:YAG laser (5.2 J/cm2, 85 mJ, 2 Hz) and another non-irradiated slab on each side of the appliance, during one phase of 5 d, under a split-mouth design. Devices were subjected to erosive challenges (1% citric acid, 5 min, 3 times a day) and abrasive challenges one h after (brushing force of 1.5 N for 15 s) randomly and independently on each side of the device. Measurements of enamel loss were performed via 3D optical profilometry (μm). We analyzed data using the Kruskal-Wallis and Mann-Whitney tests and morphological characteristics via scanning electron microscopy. Results Following erosive and abrasive challenges, the group that was irradiated with the Er:YAG laser presented less loss of structure than the non-irradiated group. The group that underwent erosion and irradiation did not exhibit a significant difference from the non-irradiated group. Conclusion Irradiation with the Er:YAG laser did not control the loss of structure of enamel subjected to erosion but did control abrasion after erosion.

Effect of CPP-ACP paste with and without CO2 laser irradiation on demineralized enamel microhardness and bracket shear bond strength

ABSTRACT Introduction: Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments. The aim of this in vitro study was to evaluate the effect of CPP-ACP paste and CO2 laser irradiation on demineralized enamel microhardness and shear bond strength of orthodontic brackets. Methods: Eighty caries-free human premolars were subjected to a demineralization challenge using Streptococcus mutans. After demineralization, the samples were randomly divided into five equal experimental groups: Group 1 (control), the brackets were bonded without any surface treatment; Group 2, the enamel surfaces were treated with CPP-ACP paste for 4 minutes before bonding; Group 3, the teeth were irradiated with CO2 laser beams at a wavelength of 10.6 µm for 20 seconds. The samples in Groups 4 and 5 were treated with CO2 laser either before or through CPP-ACP application. SEM photomicrographs of a tooth from each group were taken to observe the enamel surface. The brackets were bonded to the buccal enamel using a conventional method. Shear bond strength of brackets and ARI scores were measured. Vickers microhardness was measured on the non-bonded enamel surface. Data were analyzed with ANOVA and Tukey test at the p< 0.05 level. Results: The mean shear bond strength and microhardness of the laser group were higher than those in the control group and this difference was statistically significant (p< 0.05). All groups showed a higher percentage of ARI score 4. Conclusion: CO2 laser at a wavelength of 10.6 µm significantly increased demineralized enamel microhardness and enhanced bonding to demineralized enamel.

RESUMO Introdução: muitos pacientes, ao buscar o tratamento ortodôntico, já apresentam lesões incipientes no esmalte e precisam ser submetidos a tratamentos preventivos. O objetivo do presente estudo in vitro foi avaliar o efeito da pasta CPP-ACP e da irradiação com laser de CO2 na microdureza do esmalte desmineralizado e na resistência ao cisalhamento de braquetes ortodônticos. Métodos: oitenta pré-molares humanos hígidos foram submetidos a desmineralização usando Streptococcus mutans. Após a desmineralização, as amostras foram divididas aleatoriamente em cinco grupos experimentais: Grupo 1 (controle), os braquetes foram colados sem qualquer tratamento de superfície; Grupo 2, a superfície do esmalte foi tratada com pasta CPP-ACP por 4 minutos antes da colagem; Grupo 3, os dentes foram irradiados com laser de CO2 no comprimento de onda de 10,6 µm, por 20 segundos; Grupos 4 e 5, as amostras foram tratadas com laser de CO2 antes ou durante a aplicação de CPP-ACP. Foram feitas fotomicrografias por Microscopia Eletrônica de Varredura (MEV) de um dente de cada grupo, para avaliação da superfície do esmalte. Os braquetes foram colados ao esmalte na face vestibular, usando-se o método convencional. Foram medidos a resistência ao cisalhamento dos braquetes e o escore do Índice de Adesivo Remanescente (ARI). A microdureza Vickers foi medida nas superfícies do esmalte onde não foi realizada colagem. Os dados foram analisados com ANOVA e teste Tukey ao nível de p< 0,05. Resultados: a média da força de resistência ao cisalhamento e da microdureza do grupo laser foi superior à do grupo controle, com diferença estatisticamente significativa (p < 0,05). Todos os grupos apresentaram maior porcentagem do escore ARI=4. Conclusões: o laser de CO2 no comprimento de onda de 10,6 µm aumentou significativamente a microdureza do esmalte desmineralizado e melhorou a adesão dos braquetes nele.

Evaluation of Surface Roughness and Bacterial Adhesion on Tooth Enamel Irradiated With High Intensity Lasers

Abstract The aim was to evaluate the surface roughness and bacterial adhesion on enamel irradiated with high intensity lasers, associated or not to a fluoride varnish. Eighty fragments of bovine enamel were equally divided in 8 groups (n=10). Group 1 was not treated and Group 2 received only a 5% fluoride varnish application. The other groups were irradiated with an Er:Cr:YSGG (8.92 J/cm2), an Nd:YAG (84.9 J/cm2) and a diode laser (199.04 J/cm2), associated or not to a 5% fluoride varnish. The surface roughness was measured before and after treatments. Afterward, all samples were incubated in a suspension of S. mutans at 37 °C for 24 h. The colony-forming units (CFU) were counted by a stereoscope and the results were expressed in CFU/mm2. One-way ANOVA and the Tukey´s test compared the roughness data and the Student´s test compared the results obtained in the bacterial adhesion test (a=5%). The results showed that the irradiated samples without varnish presented the same roughness and the same bacterial adhesion that the non-irradiated samples. However, samples irradiated in the presence of fluoride varnish showed higher surface roughness and higher bacterial adhesion than the non-irradiated samples and those irradiated without varnish. Presence of pigments in the varnish increased the lasers’ action on the enamel surface, which produced ablation in this hard tissue and significantly increased its surface roughness. For this reason, the enamel’s susceptibility to bacterial adhesion was higher when the irradiation of the samples was made in presence of fluoride varnish.

Resumo O objetivo foi avaliar a rugosidade superficial e adesão bacteriana no esmalte dental irradiado com lasers de alta intensidade, associados ou não a um verniz fluoretado. Oitenta fragmentos de esmalte foram igualmente divididos em 8 grupos (n= 10). O grupo 1 não recebeu tratamento e o grupo 2 recebeu aplicação de verniz fluoretado a 5%. Os outros grupos foram irradiados com os lasers Er,Cr:YSGG (8,92 J/cm2), Nd:YAG (84,9 J/cm2) e um laser de diodo (199,04 J/cm2), associados ou não ao verniz fluoretado. A rugosidade superficial foi medida antes e após os tratamentos. Depois, todas as amostras foram imersas em suspensão de S. mutans a 37 °C durante 24 h. As unidades formadoras de colônia (UFC) foram contadas utilizando uma lupa estereoscópica, e os resultados foram expressos em UFC/mm2. Os resultados de rugosidade foram analisados por ANOVA e pelo teste de Tukey, e a adesão bacteriana foi analisada pelo teste de Student (a=5%). As amostras irradiadas sem verniz apresentaram a mesma rugosidade superficial e a mesma adesão bacteriana que as amostras não irradiadas. No entanto, as amostras irradiadas na presença do verniz fluoretado apresentaram maior rugosidade superficial e aderência bacteriana do que as amostras não irradiadas e daquelas irradiadas sem o verniz. A presença de pigmentos no verniz aumentou a ação dos lasers na superfície do esmalte, promovendo a ablação do tecido duro e aumentando significativamente a sua rugosidade superficial. Por isso, a adesão bacteriana no esmalte foi maior quando a irradiação foi realizada na presença do verniz fluoretado.

Characterisation and microleakage of a new hydrophilic fissure sealant - UltraSeal XT® hydro

ABSTRACT Objectives The aim of this study was to characterise the new hydrophilic fissure sealant, UltraSeal XT® hydro™ (Ultradent Products, USA), and to investigate its in vitro resistance to microleakage after placement on conventionally acid etched and sequentially lased and acid etched molars. Material and Methods The sealant was characterised by Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Vickers indentation test. Occlusal surfaces of extracted human molars were either conventionally acid etched (n=10), or sequentially acid etched and laser irradiated (n=10). UltraSeal XT® hydro™ was applied to both groups of teeth which were then subjected to 2,500 thermocycles between 5 and 55°C prior to microleakage assessment by fuchsin dye penetration. Results UltraSeal XT® hydro™ is an acrylate-based sealant that achieved a degree of conversion of 50.6±2.2% and a Vickers microhardness of 24.2±1.5 under standard light curing (1,000 mWcm-2 for 20 s). Fluoride ion release is negligible within a 14-day period. SEM and EDX analyses indicated that the sealant comprises irregular submicron and nano-sized silicon-, barium-, and aluminium-bearing filler phases embedded in a ductile matrix. Laser preconditioning was found to significantly reduce microleakage (Mann-Whitney U test, p<0.001). The lased teeth presented enhanced surface roughness on a 50 to 100 μm scale that caused the segregation and concentration of the filler particles at the enamel-sealant interface. Conclusion Laser preconditioning significantly decreased microleakage and increased enamel surface roughness, which caused zoning of the filler particles at the enamel-sealant interface.

CO2 laser and/or fluoride enamel treatment against in situ/ex vivo erosive challenge

ABSTRACT Objective This in situ/ex vivo study investigated the effect of CO2 laser irradiation and acidulated phosphate fluoride gel (APF) application, separately and in combination, on enamel resistance to erosion. Material and Methods During 2 experimental 5-day crossover phases, 8 volunteers wore intraoral appliances containing bovine enamel blocks which were submitted to four groups: 1st phase - control, untreated and CO2 laser irradiation, 2nd phase - fluoride application and fluoride application before CO2 laser irradiation. Laser irradiation was performed at 10.6 µm wavelength, 5 µs pulse duration and 50 Hz frequency, with average power input and output of 2.3 W and 2.0 W, respectively (28.6 J/cm2). APF gel (1.23%F, pH 3.5) was applied on enamel surface with a microbrush and left on for 4 minutes. Then, the enamel blocks were fixed at the intraoral appliance level. The erosion was performed extraorally 4 times daily for 5 min in 150 mL of cola drink. Enamel loss was measured profilometrically after treatment and after the in situ phase. The data were tested using one-way Repeated Measures Anova and Tukey's test (p<0.05). Results CO2 laser alone (2.00±0.39 µm) did not show any significantly preventive effect against enamel erosion when compared with the control group (2.41±1.20 µm). Fluoride treated enamel, associated (1.50±0.30 µm) or not (1.47±0.63 µm) with laser irradiation, significantly differed from the control. Conclusion The APF application decreased enamel wear; however, CO2 laser irradiation did not enhance fluoride ability to reduce enamel wear.

Effect of high energy X-ray irradiation on the nano-mechanical properties of human enamel and dentine

Abstract Radiotherapy for malignancies in the head and neck can cause common complications that can result in tooth damage that are also known as radiation caries. The aim of this study was to examine damage to the surface topography and calculate changes in friction behavior and the nano-mechanical properties (elastic modulus, nanohardness and friction coefficient) of enamel and dentine from extracted human third molars caused by exposure to radiation. Enamel and dentine samples from 50 human third molars were randomly assigned to four test groups or a control group. The test groups were exposed to high energy X-rays at 2 Gy/day, 5 days/week for 5 days (10 Gy group), 15 days (30 Gy group), 25 days (50 Gy group), 35 days (70 Gy group); the control group was not exposed. The nanohardness, elastic modulus, and friction coefficient were analyzed using a Hysitron Triboindenter. The nano-mechanical properties of both enamel and dentine showed significant dose-response relationships. The nanohardness and elastic modulus were most variable between 30-50 Gy, while the friction coefficient was most variable between 0-10 Gy for dentine and 30-50 Gy for enamel. After exposure to X-rays, the fracture resistance of the teeth clearly decreased (rapidly increasing friction coefficient with increasing doses under the same load), and they were more fragile. These nano-mechanical changes in dental hard tissue may increase the susceptibility to caries. Radiotherapy caused nano-mechanical changes in dentine and enamel that were dose related. The key doses were 30-50 Gy and the key time points occurred during the 15th-25th days of treatment, which is when application of measures to prevent radiation caries should be considered.

The combined use of Er, Cr: YSGG laser and fluoride to prevent root dentin demineralization

The use of erbium lasers to prevent caries in enamel has shown positive results. However, it is not known if Er,Cr:YSGG laser can also be used to increase acid resistance of root dentine, which is another dental tissue susceptible to the action of cariogenic bacteria. Objective: To analyze the effects of the Er,Cr:YSGG laser (λ=2.78 μm, 20 Hz) irradiation associated with 2% neutral sodium fluoride (NaF) to prevent root dentin demineralization. Material and Methods: One hundred human root dentin samples were divided into 10 groups (G) and treated as follows: G1: no treatment; G2: NaF; G3: laser (4.64 J/cm2) with water cooling (WC=5.4 mL/min); G4: laser (4.64 J/cm2) without WC; G5: laser (8.92 J/cm2) with WC; G6: laser (8.92 J/cm2) without WC; G7: laser (4.64 J/cm2) with WC and NaF; G8: laser (4.64 J/cm2) without WC and NaF; G9: laser (8.92 J/cm2) with WC and NaF; G10: laser (8.92 J/cm2) without WC and NaF. The NaF gel was applied alone or after 4 min of irradiation. After 14 days of acid challenge, the samples were sectioned and the Knoop microhardness (KHN) test was done at different depths (30, 60, 90 and 120 μm) from the outer dentin surface. Data were analyzed by one-way ANOVA and Fisher’s test (α=5%). Results: The results showed that G8 and G10 presented higher KHN than the G1 for the depths of 30 and 60 μm, indicating an increase of the acid resistance of the dentin in up to 35% (p<0.05). Conclusions: The use of Er,Cr:YSGG laser irradiation at 4.64 J/ cm2 and 8.92 J/cm2 without water cooling and associated with 2% NaF can increase the acid resistance of human root dentin. .

Bond Durability of Er:YAG Laser-Prepared Primary Tooth Enamel

This study evaluated in vitro the influence of thermocycling and water storage (WS) on the shear bond strength (SBS) of composite resin in cavities prepared in primary tooth enamel with conventional bur or Er:YAG laser. The test surfaces were obtained from 48 primary molars and randomly assigned to 2 groups (n=24), according to cavity preparation: A: bur-preparation and B: Er:YAG laser irradiation. The specimens were restored with an etch-and-rinse adhesive system and composite resin. Each group was divided into 4 subgroups (n=6) according to WS duration and number of thermal cycles (TCs): I: 24 h WS/no thermocycling; II: 7 days WS/500 TCs; III: 1 month WS/2,000 TCs; IV: 6 months WS/12,000 TCs. The specimens were tested to failure in shear strength at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by two-way ANOVA and Tukey's test. SBS means (S.D.) in MPa were: AI: 17.45 (2.03), AII:16.38 (1.49), AIII: 6.88 (0.66), AIV: 7.77 (1.53), BI: 12.32 (0.99), BII: 15.37 (2.24), BIII: 15.05 (2.01) and BIV-5.51 (1.01). WS duration and number of TCs influenced significantly the SBS values only for BIV (p<0.05). AI presented the highest SBS value, which was statistically similar to those of AII, BII and BIII. In conclusion, the adhesion of an etch-and-rinse adhesive to Er:YAG laser-irradiated primary tooth enamel was affected by the methods used to simulate degradation of the adhesive interface only when 6 months WS/12,000 TCs were employed.

Este estudo avaliou in vitro a influência da termociclagem (TC) e do armazenamento em água (AA) na resistência ao cisalhamento de resina composta ao esmalte de dentes decíduos preparados com broca convencional e laser Er:YAG. As superfícies de trabalho foram obtidas de 48 molares decíduos e divididas aleatoriamente em dois grupos (n=24), de acordo com o tipo de preparo cavitário: A - preparo com broca; B - irradiação com laser Er:YAG. Os espécimes foram restaurados com um sistema adesivo etch-and-rinse e resina composta. Cada grupo foi dividido em 4 subgrupos (n=6) de acordo com o tempo de armazenamento em água (AA) e o número de termociclagens (TCs): I - 24 h AA/0 TCs, II - 7 dias AA/500 TCs; III - 1 mês AA/2000 TCs; IV - 6 meses AA/12000 TCs. O teste de cisalhamento foi realizado em máquina de ensaio universal a uma velocidade de 0,5 mm/min. Os dados foram analisados estatisticamente pelo teste ANOVA a dois critérios e teste de Tukey. As médias de resistência ao cisalhamento (D.P.), em MPa, foram: AI: 17,45 (2,03), AII: 16,38 (1,49), AIII: 6,88 (0,66), AIV: 7,77 (1,53), BI: 12,32 (0,99), BII: 15,37 (2,24), BIII: 15,05 (2,01) e BIV-5,51 (1,01). O tempo de armazenamento em água quanto a termociclagem influenciou significativamente os valores de resistência ao cisalhamento só para o grupo BIV (p<0,05). AI apresentou o maior valor de SBS, que foi estatisticamente semelhantes aos de AII, BII e BIII. Em conclusão, a adesão de um sistema adesivo etch-and-rinse ao esmalte de dente decíduo irradiado com Er: YAG foi afetada pelos métodos empregados para simulação da degradação da interface adesiva somente quando armazenamento em água por 6 meses e 12.000 ciclos de termociclagem foram empregados.

Influence of photo-activation source on enamel demineralization around restorative materials

This study evaluated the effects of the photoactivation source and restorative material on the development of caries-like lesions on human enamel after an in vitro pH challenge. Enamel cavities were prepared in 36 blocks, which were assigned to two groups according to the restorative material: resin-modified glass ionomer (RMGI) and composite resin (CR). Samples were exposed to quartz-tungsten-halogen lamp, argon-ion laser, or light-emitting diode (n = 6). The Knoop microhardness (KHN) values of the top surface of all materials were evaluated. Restored enamel blocks were thermocycled and subjected to 10 demineralization-remineralization cycles at 37°C. KHN analysis of the superficial enamel was performed by four indentations located 100 mm from the restoration margin. The material KHN was not affected by the photoactivation source. No significant difference in KHN was noted between CR and RMGI. The enamel surface around RMGI exhibited a higher KHN (272.8 KHN) than the enamel around CR (93.3 KHN), regardless of the photoactivation source. Enamel demineralization around the dental restoration was not influenced by the photoactivation source. Less enamel demineralization was observed around the RMGI than around the CR restoration.

Effect of Nd:YAG laser combined with fluoride on the prevention of primary tooth enamel demineralization

Most studies dealing with the caries preventive action of Nd:YAG laser have been done in permanent teeth and studies on primary teeth are still lacking. The aim of this study was to evaluate in vitro the effect of Nd:YAG laser combined or not with fluoride sources on the acid resistance of primary tooth enamel after artificial caries induction by assessing longitudinal microhardness and demineralization depth. Sixty enamel blocks obtained from the buccal/lingual surface of exfoliated human primary molars were coated with nail polish/wax, leaving only a 9 mm² area exposed on the outer enamel surface, and randomly assigned to 6 groups (n=10) according to the type of treatment: C-control (no treatment); APF: 1.23% acidulated phosphate fluoride gel; FV: 5% fluoride varnish; L: Nd:YAG laser 0.5 W/10 Hz in contact mode; APFL: fluoride gel + laser; FVL: fluoride varnish + laser. After treatment, the specimens were subjected to a des-remineralization cycle for induction of artificial caries lesions. Longitudinal microhardness data (%LMC) were analyzed by the Kruskal-Wallis test and demineralization depth data were analyzed by oneway ANOVA and Fisher’s LSD test (á=0.05). APFL and APF groups presented the lowest percentage of microhardness change (p<0.05). Demineralization depth was smaller in all treated groups compared with the untreated control. In conclusion, Nd:YAG laser combined or not with fluoride gel/varnish was not more effective than fluoride alone to prevent enamel demineralization within the experimental period.

A maioria dos estudos que utilizam o laser Nd:YAG com ação preventiva são em dentes permanentes, e são escassos os estudos em dentes decíduos. Desta forma, o objetivo do presente estudo foi avaliar in vitro o efeito do laser Nd: YAG combinado ou não com flúor na resistência ácida do esmalte decíduo após a indução de cárie artificial, através da avaliação de microdureza longitudinal e profundidade da desmineralização. Para tanto, foram selecionados 60 fragmentos de esmalte obtidos a partir da superfície bucal / lingual de molares decíduos irrompidos, os quais foram isolados com esmalte de unha e cera, deixando uma área exposta de 9 mm² na superfície do esmalte. Os espécimes foram divididos aleatoriamente em 6 grupos (n = 10) de acordo com o tipo de tratamento: C- Controle: sem tratamento; APF: aplicação de gel flúor fosfato acidulado 1,23%; FV: aplicação de verniz fluoretado 5%; L: aplicação do Laser Nd:YAG 0,5 W/10 Hz no modo contato; APFL: aplicação de gel flúor fosfato acidulado + Laser Nd:YAG; FVL: aplicação de verniz fluoretado 5% + Laser Nd:YAG. Após os tratamentos, os espécimes foram submetidos a um ciclo de desremineralização para a indução de lesão de cárie artificial. Os dados de microdureza longitudinal (%LMC) foram avaliados pelo teste de Kruskal-Wallis e os dados de profundidade da desmineralização foram avaliados pelos testes ANOVA e Fisher’s LSD (α=5%). Observou-se que os grupos APFL e APF apresentaram menor percentual de perda de dureza (p<0,05). A profundidade de desmineralização foi menor em todos os grupos tratados em comparação com o controle. Em conclusão, o laser Nd: YAG associado ou não com flúor/verniz não foi mais efetivo do que o flúor sozinho para prevenir a desmineralização do esmalte durante o período experimental.

In vitro study of microleakage of different techniques of surface preparation used in pits and fissures.

Objective : The purpose of this in vitro study was to evaluate the effect of different techniques of surface preparation on the microleakage of a sealant applied with traditional acid etching and self-etched bonding agent. Study Design : A total of 60 extracted third molars were randomly assigned into six groups (n = 10/each). The occlusal surfaces were sealed with a sealant (Clinpro) after one of the following pretreatments: (1) phosphoric acid etching; (2) Prompt L-Pop; (3) laser + etching; (4) laser + Prompt L-Pop; (5) air abrasion + etching; (6) air abrasion + Prompt L-Pop. The specimens were immersed in a 0.5% basic fuchsin solution. Buccolingual cuts parallel to the long axis of the tooth were made. The surfaces were scored 0--2 for extent of microleakage using a microscope and the data were analyzed statistically. Results : The poorest results were obtained with laser + Prompt L-Pop which showed a greater number of specimens with microleakage (80%). Air abrasion surface preparation + phosphoric acid etching showed less microleakage than the other groups (40%). Kruskal--Wallis and t-tests revealed no significant difference in microleakage between six groups. Conclusion : The self-etching adhesive studied seems an attractive alternative to the acid-etch technique for sealant application in young children where simplifications in the clinical procedure are warranted. No significant difference was noted between the different types of enamel preparation before fissure sealant.

Efeito da irradiação laser associada à aplicação tópica de fluoreto sobre o esmalte submetido à erosão e/ou abrasão / Effect of laser irradiation associated with topic application of fluoride on sound enamel submetted to erosion and/or abrasion

A aplicação do laser sobre o esmalte associada ou não a aplicação tópica de fluoreto têm demonstrado aumentar sua resistência à ação de ácidos. O presente estudo teve como objetivo avaliar o efeito da irradiação laser de alta potência associada à aplicação de fluoretos sobre o esmalte dentário submetido à erosão e/ou abrasão dentária. Para tal, 184 blocos de esmalte foram selecionados pela microdureza de superfície (SMH inicial) e foram divididos em 8 grupos com 23 espécimes cada (3 foram utilizados para realização da biópsia básica da superfície de esmalte dentário, 10 foram submetidos à erosão e os outros 10 à erosão associada à abrasão): G1- sem tratamento (controle); G2- tratamento com flúor fosfato acidulado (1,23% F) por 4 min; G3- verniz fluoretado; G4- irradiação com laser Nd:YAG (56,6 J/cm2); G5- aplicação de flúor fosfato acidulado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G6- aplicação de flúor fosfato acidulado e prévia irradiação com laser Nd:YAG (56,6 J/cm2); G7- aplicação de verniz fluoretado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G8- aplicação de verniz fluoretado e prévia irradiação com laser Nd:YAG (56,6 J/cm2). Após os tratamentos, os blocos submetidos à ciclagem erosiva sofreram 4 imersões diárias em bebida ácida com pH 2,6, 0,32 ppm F (Coca-Cola Company, Spal, Porto Real, RJ, Brasil), por 2 min, seguida pela imersão em solução remineralizadora por 2 h, durante 5 dias. Nos blocos submetidos à erosão associada à abrasão, uma vez ao dia após cada ciclo, os espécimes foram submetidos à abrasão com 40 ciclos de escovação simulada com força de 2,5 N. Os blocos de esmalte foram avaliados por meio da perfilometria. Os resultados foram submetidos à ANOVA a um (biopsia básica) e dois critérios (perfilometria) e Teste de Tukey (p<0,05). Todos os grupos de tratamento promoveram menor desgaste dentário em relação ao controle, sendo que entre eles, a irradiação laser promoveu o pior...

The laser application on enamel associated or not to the topic fluoride have been showed to increase the resistance to acid action. This study aimed to evaluate the effect of high intensity laser irradiation submitted to dental erosion and/or abrasion. Hence, 184 enamel samples were selected by surface microhardness (initial SMH) and then divided into 8 groups with 23 specimens each (3 were selected to routine biopsy of enamel surface, 10 submitted to erosion procedure and another 10 were submitted to erosion associated to abrasion): G1 without treatment (control group); G2 treated with acidic phosphate for 4 min (1.23% F); G3 fluoride varnish; G4 - irradiation with Nd:YAG laser (56.6 J/cm2) ; G5 - acidic phosphate fluoride with posterior irradiation with Nd:YAG laser (56.6 J/cm2) ; G6 application of acidic phosphate fluoride with previous irradiation of Nd:YAG laser (56,6 J/cm2); G7- application of fluoride varnish with posterior laser irradiation with Nd:YAG laser (56,6 J/cm2); G8- application of fluoride varnish with previous irradiation of Nd:YAG laser (56,6 J/cm2). After the treatments, the samples were submitted to erosive cycling with 4 diary immersions in acidic beverages with pH 2.6, 0.32 F ppm (Coca-Cola Company, Spal, Porto Real, RJ, Brasil) for 2 min followed by remineralized solution for 5 days. To groups submitted to erosive associated to abrasion, once a day after each cycling, the specimens were submitted to abrasion with 40 simulated brushing cycles with power of 2.5 N. The enamel samples were evaluated by profilemetry. The results were submitted to one way ( routine biopsy) and two way (profilometry) ANOVA and Tukey test (p < 0.05). All the groups demonstrated a wear dental decrease in relation to control group, and among them, the laser irradiation promoted the worst outcome (p < 0.05). The groups related to fluoride resulted in increase concentration of fluoride in the enamel...

Efeito da irradiação laser associada à aplicação tópica de fluoreto sobre o esmalte submetido à erosão e/ou abrasão / Effect of laser irradiation associated with topic application of fluoride on sound enamel submetted to erosion and/or abrasion

A aplicação do laser sobre o esmalte associada ou não a aplicação tópica de fluoreto têm demonstrado aumentar sua resistência à ação de ácidos. O presente estudo teve como objetivo avaliar o efeito da irradiação laser de alta potência associada à aplicação de fluoretos sobre o esmalte dentário submetido à erosão e/ou abrasão dentária. Para tal, 184 blocos de esmalte foram selecionados pela microdureza de superfície (SMH inicial) e foram divididos em 8 grupos com 23 espécimes cada (3 foram utilizados para realização da biópsia básica da superfície de esmalte dentário, 10 foram submetidos à erosão e os outros 10 à erosão associada à abrasão): G1- sem tratamento (controle); G2- tratamento com flúor fosfato acidulado (1,23% F) por 4 min; G3- verniz fluoretado; G4- irradiação com laser Nd:YAG (56,6 J/cm2); G5- aplicação de flúor fosfato acidulado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G6- aplicação de flúor fosfato acidulado e prévia irradiação com laser Nd:YAG (56,6 J/cm2); G7- aplicação de verniz fluoretado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G8- aplicação de verniz fluoretado e prévia irradiação com laser Nd:YAG (56,6 J/cm2). Após os tratamentos, os blocos submetidos à ciclagem erosiva sofreram 4 imersões diárias em bebida ácida com pH 2,6, 0,32 ppm F (Coca-Cola Company, Spal, Porto Real, RJ, Brasil), por 2 min, seguida pela imersão em solução remineralizadora por 2 h, durante 5 dias. Nos blocos submetidos à erosão associada à abrasão, uma vez ao dia após cada ciclo, os espécimes foram submetidos à abrasão com 40 ciclos de escovação simulada com força de 2,5 N. Os blocos de esmalte foram avaliados por meio da perfilometria. Os resultados foram submetidos à ANOVA a um (biopsia básica) e dois critérios (perfilometria) e Teste de Tukey (p<0,05). Todos os grupos de tratamento promoveram menor desgaste dentário em relação ao controle, sendo que entre eles, a irradiação laser promoveu o pior...

The laser application on enamel associated or not to the topic fluoride have been showed to increase the resistance to acid action. This study aimed to evaluate the effect of high intensity laser irradiation submitted to dental erosion and/or abrasion. Hence, 184 enamel samples were selected by surface microhardness (initial SMH) and then divided into 8 groups with 23 specimens each (3 were selected to routine biopsy of enamel surface, 10 submitted to erosion procedure and another 10 were submitted to erosion associated to abrasion): G1 without treatment (control group); G2 treated with acidic phosphate for 4 min (1.23% F); G3 fluoride varnish; G4 - irradiation with Nd:YAG laser (56.6 J/cm2) ; G5 - acidic phosphate fluoride with posterior irradiation with Nd:YAG laser (56.6 J/cm2) ; G6 application of acidic phosphate fluoride with previous irradiation of Nd:YAG laser (56,6 J/cm2); G7- application of fluoride varnish with posterior laser irradiation with Nd:YAG laser (56,6 J/cm2); G8- application of fluoride varnish with previous irradiation of Nd:YAG laser (56,6 J/cm2). After the treatments, the samples were submitted to erosive cycling with 4 diary immersions in acidic beverages with pH 2.6, 0.32 F ppm (Coca-Cola Company, Spal, Porto Real, RJ, Brasil) for 2 min followed by remineralized solution for 5 days. To groups submitted to erosive associated to abrasion, once a day after each cycling, the specimens were submitted to abrasion with 40 simulated brushing cycles with power of 2.5 N. The enamel samples were evaluated by profilemetry. The results were submitted to one way ( routine biopsy) and two way (profilometry) ANOVA and Tukey test (p < 0.05). All the groups demonstrated a wear dental decrease in relation to control group, and among them, the laser irradiation promoted the worst outcome (p < 0.05). The groups related to fluoride resulted in increase concentration of fluoride in the enamel...

Intrapupal temperature variation during Er,Cr: YSGG enamel irradiation on carries prevention

Studies have shown the cariostatic effect of Er,Cr:YSGG (2.78 mm) laser irradiation on human enamel and have suggested its use on caries prevention. However there are still no reports on the intrapulpal temperature increase during enamel irradiation using parameters for caries prevention. The aim of this in vitro study was to evaluate the temperature variation in the pulp chamber during human enamel irradiation with Er,Cr:YSGG laser at different energy densities. Fifteen enamel blocks obtained from third molars (3 x 3 x 3 mm) were randomly assigned to 3 groups (n=5): G1 - Er,Cr:YSGG laser 0.25 W, 20 Hz, 2.84 J/cm², G2 - Er,Cr:YSGG laser 0.50 W, 20 Hz, 5.68 J/cm², G3 - Er,Cr:YSGG laser 0.75 W, 20 Hz, 8.52 J/cm². During enamel irradiation, two thermocouples were fixed in the inner surface of the specimens and a thermal conducting paste was used. One-way ANOVA did not show statistically significant difference among the experimental groups (a=0.05). There was intrapulpal temperature variation <0.1ºC for all irradiation parameters. In conclusion, under the tested conditions, the use of Er,Cr:YSGG laser with parameters set for caries prevention lead to an acceptable temperature increase in the pulp chamber.