Scanning Electron Microscope (SEM) Evaluation of Tooth Surface Irradiated by Different Parameters of Erbium: Yttrium Aluminium Garnet (Er:YAG) Laser

INTRODUCTION: The aim of this study was to investigate the Scanning Electron Microscope (SEM) analysis of tooth surface irradiated by different parameters of Er:YAG laser.METHODS: 15 caries-free extracted human third molars were used in this study. The teeth were put into 5 groups for laser irradiation as follows: Group 1 (power: 2.5 W, Energy: 250 mJ); Group 2(power: 3 W, Energy: 300 mJ); Group 3 (power: 3.5 W, Energy: 350 mJ); Group 4 (power: 4 W, Energy: 400 mJ); Group 5 (power: 4.5 W, Energy: 450 mJ). All samples were prepared by repetition rate of 10 Hz. Then,the samples were prepared for SEM examination.RESULTS: The SEM images showed cleaned ablated surface and exposed dentinal tubules, without production of smear layer.CONCLUSION: It can be concluded that Er:YAG laser can be an alternative technique for surface treatment and can be considered as safe as the conventional methods,like turbine and bur

Surface Treatment by Different Parameters of Erbium:Yttrium–Aluminum–Garnet (Er:YAG) Laser: Scanning Electron Microscope (SEM) Evaluation

Introduction: This study aimed to assess the Scanning Electron Microscope (SEM) analysis of tooth surface irradiated by erbium:yttrium–aluminum–garnet (Er:YAG) laser with various parameters.Methods: Number of 25 extracted human third molars free of caries were used in this study. The teeth were put into 5 groups for laser irradiation as follows: group 1 (power: 0.5 W, Energy: 50 mJ); group 2 (power: 1 W, Energy: 100 mJ); group 3 (power: 1.5 W, Energy: 150 mJ); group 4 (power: 2 W, Energy: 200 mJ); group 5 (power: 2.5 W, Energy: 250 mJ). All samples were prepared by repetition rate of 10 Hz and duration of 230 μs, using a non-contact handpiece at a distance of 4 mm. Then, the samples were prepared for SEM examination.Results: SEM evaluation of every 25 samples, treated by Er:YAG, showed that all groups had exposed dentinal tubules without any melted area or cracks.Conclusion: In this study we used SEM to investigate ablated dentine with different parameters of Er:YAG laser energy. Our findings support these conclusions. All powers of laser below 3 W are proper for ablation, and make no cracks

Evaluation of the Effect of Different Laser Activated Bleaching Methods on Enamel Susceptibility to Caries; An In Vitro Model

Introduction: Today bleaching is a routine noninvasive alternative for treatment of discolored teeth. The concern has been raised whether or not oxidizing reaction during this process, might endanger integrity of the teeth and raise the risk of caries formation. The aim of this study was to determine whether conventional or laser activated bleaching predispose teeth to develop caries or not.Methods:Sixty human molars were mounted on acrylic cylinders and Knoop microhardness (KHN) and DIAGNOdent (DD) values of them were recorded. They were divided into four experimental groups; G1)conventional bleaching with 40% Hydrogen peroxide gel G2) Diode laser assisted bleaching with same gel. G3)Nd;YAG laser assisted bleaching with the same gel. G4)control group. After bleaching, all samples were subjected to a three day pH cycling regimen and then, KHN and DD values were measured.Results:All groups had significant reduction in KHN values. . It seems that there is no statistically meaningful difference between changes in enamel microhardness of sample groups and all groups have changed in a similar amount. Reduction of DD scores were significant in Diode laser and conventional groups, however changes in Nd:YAG laser and control groups were not significant. Changes in DD values have followed a similar pattern among groups, except in G1-G4 and G2-G4 couples. Conventional and Diode laser group had a meaningful difference in reduction of DD values in comparison with control group.Conclusion:It can be concluded that bleaching whether conventional or laser activated method, does not make teeth vulnerable to develop carious lesions

Validación del cuestionario CIVIQ 20 (Venous Disease Quality of Life Questionnaire - 20) en pacientes con enfermedad venosa crónica que acuden a consulta externa del servicio de cirugía vascular del Centro de Atención Ambulatoria Cotocollao - IESS, noviembre - diciembre del 2014

Objetivo: Validar el cuestionario CIVIQ 20 como una herramienta para la valoración de la calidad de vida en pacientes con desórdenes venosos crónicos en el Servicio de Cirugía Vascular del Centro de Atención Ambulatoria de Cotocollao - IESS. Tipo de estudio: Estudio transversal analítico de validación de herramientas diagnósticas. Metodología: En una muestra de 384 pacientes, comprendidos entre 23 y 88 años de edad que acuden a la Consulta externa del Servicio de Cirugía Vascular en el Centro de Atención Ambulatoria de Cotocollao – IESS, se aplicó el cuestionario CIVIQ 20 (chronic venous disease quality of life questionnaire) por un observador y seguidamente el cuestionario SF 36 por un segundo observador, para determinar la calidad de vida de los pacientes que padecen enfermedad venosa crónica. Además se empleó el HADS (Hospital Anxiety and Depression Escale). Posteriormente se analizaron las características intrínsecas (fiabilidad, precisión y validez). Resultados: De los 384 pacientes se obtuvo que el 72 % (n=275) fueron de sexo femenino y el 28% (n=109) masculino. La media de la edad fue de 54.8, con un mínimo de 23 y un máximo de 88 y una desviación estándar (DE) de 14.4. El IMC tiene una media de 28.4 (DE±4.2). La media de años a partir del diagnóstico de la enfermedad fue de 11.8 (DE ±11.7) (rango de 1 a 50). La educación formal mostró que el 41 % (n=159) de los pacientes cursaron la secundaria completa, el 31% (n=120) la educación superior y el 27% (n=105) primaria completa. La variable ocupación mostró que 71% (n=273) de los pacientes no son sedentarios, y el 29% (111) son sedentarios. En las mujeres que se incluyeron en este estudio, se observó que 56% (n=153) de ellas no presentaban consumo de anticonceptivos orales (ACO) y 44% (n=122) habían hecho uso de los mismos en algún momento de su vida. La variable estreñimiento mostró que el 70% (n=267) de los pacientes lo padecían. En cuanto a complicaciones, la TVP estuvo presente en 10% (n=38) de los pacientes, la TEP en 2% (n=6) y el 88% (340%) no presentaron complicaciones en los años que adolecen de la enfermedad. El tratamiento nos reveló que el 55% (n=210) pacientes han recibido tratamiento previo mientras que 45% (n=174) no han sido tratados. En cuanto a la aceptabilidad de los datos del cuestionario CIVIQ 20 observamos que la diferencia entre media y mediana es menor para cada uno de los dominios, excepto el dominio psicológico (1.16) y el total del CIVIQ 20 con una diferencia de 2.53. La asimetría y la curtosis cumplieron con el criterio de aceptabilidad en todos los dominios y en el CIVIQ 20 global. De la misma forma, existe un efecto techo y suelo menor al 10% en todos ellos. Para la consistencia interna se obtuvo un alfa de Cronbach de 0,932 y no mejoró al eliminar los ítems; se analizó la matriz de correlación inter-ítem con el Rho de Pearson, se obtuvieron 190 correlaciones, de las cuales el 78.9% de los datos analizados, se encontraron en el rango de correlación moderada y el 15.3 % mostraron una correlación baja

Debonding Time and Dental Pulp Temperature With the Er, Cr: YSGG Laser for Debonding Feldespathic and Lithium Disilicate Veneers

Introduction: The removal of ceramic veneers is a time-consuming procedure in a dentaloffice. Little research has been done in alternative removal techniques for ceramic veneers.The objective of this study was to evaluate the removal of feldspathic and lithium disilicatereinforced glass ceramic veneers by Er, Cr: YSGG and to measure debonding time and pulpaltemperature increase during veneer removal.Methods: Fifty-seven bovine incisor teeth were prepared and divided into 3 groups. Ceramicspecimens with a thickness of 0.7mm, a width of 4mm and a length of 8 mm were fabricatedfrom feldspathic ceramic, lithium disilicate reinforced glass ceramic HT (high translucency) andlithium disilicate reinforced glass ceramic MO (medium opacity) (19 for each group). Specimenswere cemented on the labial surface of incisors using resin cement. The Er, Cr: YSGG laserwas applied to each specimen at 2.5 W and 25 Hz. Debonding time was measured for eachspecimen, and the intrapulpal temperature was detected in 3 specimens for each group. Datawere analyzed via one-way analysis of variance (ANOVA) at significance level of 0.05 (α = 0.05).Results: Mean debonding time was 103.68 (26.76), 106.58 (47.22) and 103.84 (32.90) secondsfor feldspathic, lithium disilicate MO, and lithium disilicate HT respectively. There was nosignificant statistical difference among the groups (P value = 0.96). The intrapulpal temperatureincrease was less than 1°C in all groups.Conclusion: Er, Cr: YSGG can successfully be used to efficiently debond feldspathic and lithiumdisilicate reinforced glass ceramic veneers. There was no significant difference for debondingtime among these ceramic materials. During ceramic laminate veneer removal by laserirradiation, no irritating temperature rise was detected

Evaluating the Quality of Education at Dentistry School of Tehran University of Medical Sciences

Background: Educational evaluation is a process which deals with data collection and assessment of academic activities′ progress. In this research, educational evaluation of Dentistry School of Tehran University of Medical Sciences, which trains students in undergraduate and residency courses, was studied. Methods : This descriptive study was done with a model of educational evaluation in ten steps and 13 fields including purposes and mission objectives, management and organization, academic board members, students, human resources and support, educational, research, health and treatment spaces, educational, diagnostic, research and laboratory tools, educational, research, health and treatment programs and courses, process of teaching and learning, evaluation and assessment, alumni, and patients satisfaction. Data were collected using observation, interviews, questionnaires, and checklists. Results: Results of the study were mainly qualitative and in some cases quantitative, based on defined optimal situation. The total mean of qualitative results of educational evaluation of dentistry school in all 13 fields was 55.98% which is relatively desirable. In the case of quantitative ones, results of some fields such as treatment quality of patients and education and learning of the students were relatively desirable (61.32% and 60.16% respectively). Conclusion: According to the results, educational goals and missions, educational and research facilities and spaces which were identified as the weakest areas need to be considered and paid more serious attention

Inhibitory Effects of Antimicrobial Photodynamic Therapy with Curcumin on Biofilm-Associated Gene Expression Profile of Aggregatibacter actinomycetemcomitans

Objectives: Periodontitis is an inflammation of periodontal tissues that is caused by the biofilm of periodontal pathogens. Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is an opportunistic periodontopathogen that can be the cause of periodontal diseases via fimbriae as a virulence factor. In this study, we aimed to determine the expression level of A. actinomycetemcomitans rcpA gene as a virulence factor associated with biofilm formation after antimicrobial photodynamic therapy (aPDT) as a relatively new therapeutic modality. Materials and Methods: To determine sub-lethal doses of aPDT against A. actinomycetemcomitans ATCC 33384 strain, we used curcumin (CUR) as a photosensitizer at a final concentration of 40 µmol/ml, which was excited with a light-emitting diode (LED) at the wavelength of 450 nm. Quantitative real-time polymerase chain reaction (qRT-PCR) was then applied to monitor rcpA gene expression in A. actinomycetemcomitans. Results: 10-40 μmol/ml of CUR caused a significant reduction in the growth of A. actinomycetemcomitans compared to control group (P<0.05). Also, the cell viability of A. actinomycetemcomitans was significantly decreased after more than four minutes of LED irradiation. Therefore, the sub-lethal dose of aPDT against A. actinomycetemcomitans was 5 μmol/ml of CUR with three minutes of LED irradiation at a fluency of 180-240 J/cm2, which reduced the expression of the rcpA gene by approximately 8.5-fold. Conclusions: aPDT with CUR leads to decreased cell survival and virulence of A. actinomycetemcomitans. Thus, CUR-aPDT can be used as an alternative approach for the successful treatment of periodontitis in vivo

Comparison of Fracture Resistance and Failure Mode of Different Zirconia Abutments with Titanium Abutment

Background and Aims: One of the decicive factors on the final esthetic results of implant treatment is theabutment material. Ceramic abutments are nowadays very popular in this regard. The purpose of this study was tocompare the fracture resistance of three zirconia abutments with titanium abutment.Materials and Methods: Four groups of abutments 4 recorded for each specimen. The data were analyzed using One-way ANOVA.Results: The mean values recorded for fracture resistance of different zirconia abutments varied between 426 to688 N; however, there was no significant differences among the group

Accuracy of implant transfer with open-tray and closed-tray impression techniques and surface detail reproduction of the tooth during impression

Background and Aims: Accurate recording of implant location is required to achieve passive fit and have the implants without stress concentration. The aim of this in-vitro study was to evaluate the dimensional and angular accuracy of open-tray and closed-tray impression techniques using polyether impression material and also to assess the surface detail reproduction of the tooth while impression making.Materials and Methods: One reference metal model with 2 implants (Implantium) on the position of the maxillary second premolar and first molar and one molar tooth for evaluation of surface details was prepared. 27 polyether impressions of these models were made (9 using open-tray, 9 using closed-tray techniques and 9 were made just of the surface of the teeth without any implants). Impressions were poured with ADA type IV stone. Coordinate Measuring Machine was used for measuring the dimensional accuracy and video measuring machine for surface detail reproduction. All of these measurements were compared with the measurements on the reference model. Data were analyzed by and compared by T-test and One-way ANOVA.Results: There was a significant statistical difference between open-tray and closed-tray techniques (P<0.001). There was no significant difference in the surface detail reproduction of open-tray and Closed-tray techniques and impression making with or without the implants (P>0.05).Conclusion: The accuracy of open-tray impression technique was more than closed-tray technique. The surface detail reproduction of the tooth was not affected by impression technique

Implant Surface Temperature Changes during Er:YAG Laser Irradiation with Different Cooling Systems.

Peri-implantitis is one of the most common reasons for implant failure. Decontamination of infected implant surfaces can be achieved effectively by laser irradiation; although the associated thermal rise may cause irreversible bone damage and lead to implant loss. Temperature increments of over 10ºC during laser application may suffice for irreversible bone damage.The purpose of this study was to evaluate the temperature increment of implant surface during Er:YAG laser irradiation with different cooling systems.Three implants were placed in a resected block of sheep mandible and irradiated with Er:YAG laser with 3 different cooling systems namely water and air spray, air spray alone and no water or air spray. Temperature changes of the implant surface were monitored during laser irradiation with a K-type thermocouple at the apical area of the fixture.In all 3 groups, the maximum temperature rise was lower than 10°C. Temperature changes were significantly different with different cooling systems used (