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Avaliação dos cuidados com aparelhos fotoativadores e procedimentos de fotoativação
Abstract
O uso de resinas compostas está aumentando devido ao seu melhor resultado estético, maior longevidade e altas propriedades mecânicas. Nelas, possuem um componente sensível à luz, que responde a irradiação criando radicais livres e inicia o processo de polimerização, transformando monômeros em polímeros. A resistência das restaurações depende do seu grau de polimerização, uma polimerização incompleta produz efeitos biológicos adversos. Diante disso, o objetivo do presente trabalho é avaliar as práticas de fotopolimerização de cirurgiões-dentistas atuantes no estado do Espírito Santo por meio da utilização de um questionário. O questionário foi encaminhado ao CRO-ES para que pudesse ser enviado por mala direta aos profissionais que atuam no estado e estão devidamente inscritos. A partir dos resultados foi feito o levantamento das práticas de fotopolimerização dos participantes e uma comparação entre os profissionais com diferentes experiências acumuladas. Duas perguntas do questionário apresentaram um resultado com relevância estatística, a primeira em relação ao tipo de aparelho que ele utilizava, onde houve uma predominância de 58,1% para profissionais formados acima de 15 anos que souberam responder. A segunda pergunta foi se faziam o uso de proteção ocular, 66,98% dos participantes revelaram não fazer uso de proteção ocular durante os procedimentos de fotoativação. Conclui-se que apesar do baixo índice de insucesso relatado pelos profissionais, o índice de acertos para as perguntas do questionário foi baixo, além disso, houve uma relação entre o índice de acerto com um maior tempo de experiência clínica.
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Introdução: Falhas no processo de polimerização levam o material resinoso a sofrer alterações estruturais, como menor resistência ao desgaste, degradação na matriz orgânica, infiltrações e absorção de água. Diversos tipos de aparelhos fotopolimerizadores têm sido lançados no mercado, com o intuito de permitir diferentes métodos de fotoativação. É de suma importância saber qual fotopolimerizador deve ser usado para o tipo de fotoiniciador composto no material resinoso. Objetivo: O objetivo desta revisão de literatura é analisar diferentes fotopolimerizadores e fotoiniciadores para polimerização de resinas compostas. Metodologia: A revisão de literatura contou com uma busca em bancos de dados científicos online nacionais e internacionais, selecionando artigos publicados a partir de 2008, em português, inglês e espanhol, utilizando os descritores light curing of dental adhesives; photoinitiators, dental; polymerization; curing lights dental e suas respectivas traduções para o idioma português, disponíveis na biblioteca Medical Subjects Headings (MeSH). Discussão: Observou-se que existem fotopolimerizadores no mercado que diferem quanto ao tipo de luz, potência e intensidade. Para assegurar uma efetiva polimerização dos materiais resinosos e uma durabilidade clínica dos procedimentos restauradores, o uso dos aparelhos fotopolimerizadores com diferentes espectros de luz dependem do tipo de fotoiniciador presente na matriz resinosa. Considerações finais: Concluiu-se que é de suma importância o desenvolvimento dos aparelhos fotoativadores, compostos fotoiniciadores e materiais resinosos, no intuito de uma maior longevidade clínica dos procedimentos restauradores realizados. Introduction: When faults occur in the polymerization process, the resinous material undergoes structural changes, such as lower wear resistance, organic matrix degradation, infiltration and water absorption. Several types of light-curing devices have been launched in the market, in order to allow different methods of photoactivation. It is of utmost importance to know which curing light should be used for the type of photoinitiator composed in the resinous material. Objective: The objective of this literature review is to analyze different curing light and photoinitiators for polymerization of composite resins. Methodology: The literature review included a search in national and international online scientific databases, using articles published since 2008, in Portuguese, English and Spanish, using the descriptors light curing of dental adhesives; photoinitiators, dental; polymerization; curing lights dental and their respective translations into Portuguese, available from the Medical Subjects Headings (MeSH) library. Discussion: There are curing lights in the market with which they differ in light type, power and intensity. To ensure an effective polymerization of the resinous materials and a clinical durability of the restorative procedures, the light type of the curing lights depend on the type of photoinitiator being used. Final considerations: It is concluded that the development of photoactivating devices, photoinitiating compounds and resinous materials is of paramount importance, aiming at a greater clinical longevity of the restorative procedures performed.
O objetivo do presente estudo foi avaliar a irradiância de diferentes fotoativadores quando submetidos a utilização de diferentes tipos de barreiras de proteção biológica. Os aparelhos testados foram Bluephase N. Radii-Cal e VALO cordless. As barreiras de biossegurança foram: Polietileno. Policloreto de vinila com 1 volta e Policloreto de vinila com 2 voltas. As pontas dos aparelhos tiveram seu diâmetro aferido a partir de um paquímetro digital e a área de cada ponteira foi calculada. A potência (mW) dos aparelhos foi medida com um potenciômetro por 20 segundos. e três vezes para cada aparelho. E então. a irradiância (mW / cm²) foi calculada pelo quociente da potência do aparelho pela área da seção transversal da ponta do fotopolimerizador. O teste anova dois fatores demonstrou interação estatisticamente significante entre os diferentes tipos de aparelhos fotopolimerizadores e barreiras de proteção biológica (p < 0.05). Dentre os fotopolimerizadores. Bluephase N obteve os maiores valores de irradiância independente do tipo de barreira. seguido do VALO cordless e Radii-Cal. Todos os aparelhos obtiveram maior irradiância no grupo controle. quando não faziam uso de barreiras descartáveis. Dentre as barreiras. o policloreto de vinila com 1 volta obteve o melhor desempenho em todos os grupos de fotopolimerizadores. Apesar do uso de barreiras de biossegurança terem reduzido a irradiância dos aparelhos. esses valores não foram inferiores ao mínimo adequado para a polimerização de resinas compostas convencionais (400 mW/cm²).
Objectives:
Light curing is crucial when applying composite resin restorations. Complete polymerization of the resin depends on delivering adequate light energy to it. Dental clinicians may be unaware of the importance of proper light-curing techniques. This study aimed at evaluating and comparing the level of knowledge of general practitioners (GPs) and specialists (SPs) regarding light-curing units.
Materials and methods:
An electronic survey was conducted online among GPs and SPs of various specialties, working in the governmental sector in Riyadh, Saudi Arabia. Collected data were analyzed for statistical significance.
Results:
310 dentists were included in the study. Nearly half of the GPs (45.9%) and more than half of SPs (56.8%) use light-emitting diode (LED) type light-curing units (LCUs). 36.9% of GPs and 29.6% of SPs were unsure about the type of LCUs they use in their dental clinics. 10.8% of GPs and 8.5% of SPs knew the proper term of the power output of LCU. 52.2% of the GPs and 55.7% of SPs were wrong about advancements in technology of LED LCUs. Regarding the use of radiometer, 48.2% of SPs and 35.1% of GPs had responded wrongly, and 37.7% of SPs and 52.3% of GPs were not familiar with the device, showing a statistical significance (p=0.040). There was no statistical significance observed in the responses pertaining to their years of experience, expected for two questions.
Conclusion:
Both GPs and SPs displayed inadequate knowledge regarding the use of LCUs. Further educational programs are recommended to spread awareness about the handling of LCUs among dental clinicians.
Background
Human papillomavirus (HPV) is a sexually transmitted oncovirus associated with several malignancies, including oropharyngeal squamous cell carcinoma. The 9-valent HPV vaccine can help protect against the high-risk HPV strains most commonly associated with HPV-related cancers.
Methods
The authors used an electronic survey to assess the roles of dentists and their team members in discussing the HPV vaccine, as well as administering the vaccine in a dental setting. On December 6, 2019, the authors e-mailed a survey link to the American Dental Association Clinical Evaluators (ACE) Panel (n = 813), a sample of American Dental Association member dentists. After 1 e-mail reminder, the survey closed on December 19, 2019, and the authors conducted exploratory and descriptive data analyses using SAS Version 9.4 (SAS).
Results
A total of 329 dentists responded to the survey, and 83 (25%) of them reported that they or their team members discuss the implications of the HPV vaccine with age-eligible patients or their parents or guardians. Dentists lead two-thirds (n = 218) of the discussions, and the clinical examination is the most frequent moment during the patient visit in which HPV-related topics are discussed. Some of the top reasons respondents mentioned for not discussing the vaccine in their practice were the perception that these discussions are best left to other health care professionals and not knowing how to address the topic with patients. If the scope of dental practice is expanded to include administering the vaccine, 125 (38%) of respondents would feel uncomfortable administering the vaccine. The most common potential barriers to administering the vaccine in a dental setting include obtaining reimbursement and vaccine management and preservation.
Conclusions
The survey results suggest that dentists’ comfort levels and perceived roles in discussing and administering the HPV vaccine vary.
Practical Implications
There is a need to further define the role of dentists and their team members in the promotion and administration of the HPV vaccine. Resources for dentists and dental team members may be helpful to support professional education and communication about the HPV vaccine.
Background:
The aims of the study were measuring the light intensity of light curing units used in Qazvin's dental offices, determining the relationship between the clinical age of these units and their light intensity, and identifying the reasons for repairing them.
Material and methods:
In this cross-sectional study, the output intensity of 95 light curing devices was evaluated using a radiometer. The average output intensity was divided up into four categories (less than 200, 200-299, 300-500, and more than 500 mW/cm2). In addition, a questionnaire was designed to obtain information mainly about the type, clinical age, and frequency of maintenance of the units and the reasons for fixing them. Data were analyzed using Kolmogorov-Smirnov, chi-squared, and t-tests (p< 0.05) on SPSS 24.
Results:
A total of 95 light curing units were examined, with 61 (64.2%) of them being of the LED type and 34 (35.8%) of the QTH type. While average light intensity in LED units was significantly higher than in QTH devices, the two device types were not significantly different regarding desirable light intensity (i.e., ≥ 300 mw/cm2). A negative correlation was observed between clinical age and light intensity. In addition, bulb replacement in QTH devices was over three times as much as in LED units. Also, repairing QTHs was more than twice as much frequent as fixing LEDs. The most common reason for repair was the breakage of the tip of the device.
Conclusions:
The light intensity of LED units is significantly higher than that of QTH devices, and the frequency of repairing in QTHs was significantly more than in LEDs. Furthermore, light intensity decreases with aging, and dentists should regularly monitor the conditions of light units. Key words:Light curing unit, radiometer, light intensity, dental equipment, dental offices.
Contemporary dentistry literally cannot be performed without use of resin-based restorative materials. With the success of bonding resin materials to tooth structures, an even wider scope of clinical applications has arisen for these lines of products. Understanding of the basic events occurring in any dental polymerization mechanism, regardless of the mode of activating the process, will allow clinicians to both better appreciate the tremendous improvements that have been made over the years, and will also provide valuable information on differences among strategies manufacturers use to optimize product performance, as well as factors under the control of the clinician, whereby they can influence the longterm outcome of their restorative procedures.
Objectives:
This study aimed to investigate dentists' exposure to curing light and to obtain information about the dentists' knowledge on practical use and technical features of their curing lights as well as their safety awareness.
Methods:
A pre-coded questionnaire was sent electronically to all dentists (n=1313) in the Public Dental Service (PDS) in Norway in 2015.
Results:
The Response rate was 55.8%. The dentists spent on average 57.5% of their working days placing restorations, ranging from 1 to 30 (mean 7.7, SD 3.6) restorations per day. The average length of light curing one normal layer of composite was 27s. The longest individual mean curing time per day was about 100 times higher than that of the lowest. The mean curing time for lamps of the lower reported irradiances was similar to the time representing exceedance of international guidelines for limit values for blue light to the eyes. Almost one-third of the dentists used inadequate eye protection against blue light. The odds of using adequate eye protection were significantly higher among young dentists (p<0.01). The majority of the respondents (78.3%) were unaware of the irradiance value of their curing lights, thus rendering the curing time uncertain. More dentists in this group did not perform regular maintenance of their curing lights compared with all respondents (17.1% vs. 3.3%, p<0.01).
Conclusions:
This study revealed considerable variations among Norwegian dentists in the Public Dental Service with respect to performance of light curing of restorations, safety awareness and technical knowledge of the curing light. CLINICAL SIGNIFICANCE (MAX. 50 WORDS): The questionnaire study identifies specific knowledge gaps among Norwegian dentists with regard to curing lights and use of personal protection. Today's dependence on technology in dentistry necessitates that the operator possesses knowledge of essential technical specifications and safe use of devices and instruments routinely used in dental treatment.
Objectives: To evaluate the effect of photoinitiators and reducing agents on cure efficiency and color stability of resin-based composites using different LED wavelengths.
Methods: Model resin-based composites were associated with diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) or camphorquinone (CQ) associated with 2-(dimethylamino)ethyl methacrylate (DMAEMA), ethyl 4-(dimethyamino)benzoate (EDMAB) or 4-(N,N-dimethylamino)phenethyl alcohol (DMPOH). A narrow (Smartlite, Dentisply) and a broad spectrum (Bluephase G2, Ivoclar Vivadent) LEDs were used for photo-activation (20J/cm2). Fourier transform infrared spectroscopy (FT-IR) was used to evaluate the cure efficiency for each composite, and CIELab parameters to evaluated color stability (ΔE00) after aging. The UV-vis absorption spectrophotometric analysis of each photoinitiator and reducing agent was determined. Data were analyzed using two-way ANOVA and Tukey’s test for multiple comparisons (α=0.05).
Results: Higher cure efficiency was found for type-I photoinitiators photo-activated with a broad spectrum light, and for CQ-systems with a narrow band spectrum light, except when combined with an aliphatic amine (DMAEMA). Also, when combined with aromatic amines (EDMAB and DMPOH), similar cure efficiency with both wavelength LEDs was found. TPO had no cure efficiency when light-cured exclusively with a blue narrowband spectrum. CQ-systems presented higher color stability than type-I photoinitiators, especially when combined with DMPOH.
Conclusions: After aging, CQ-based composites became more yellow and BAPO and TPO lighter and less yellow. However, CQ-systems presented higher color stability than type-I photoinitiators, as BAPO- and TPO-, despite their higher cure efficiency when photo-activated with corresponding wavelength range.
Clinical Significance: Color matching is initially important, but color change over time will be one of the major reasons for replacing esthetic restorations; despite the less yellowing of these alternative photoinitiators, camphorquinone presented higher color stability.
Clinical successful use of resin-based composite restorations (RBCs) depends on knowledge of material and light curing unit (LCU) related factors. The purpose of this study was to evaluate general dental practitioners' knowledge of polymerisation of RBCs and LCU technology.
Members of the Active Research Group of the Faculty of General Dental Practice (UK) in England, Scotland and Wales engaged in primary dental care were sent a letter introducing the study and asking for their cooperation, followed by an email containing a link to the online survey questionnaire, hosted on Surveymonkey.com. The questionnaire enquired about current LCUs, and asked a series of questions on material science.
Sixty-six percent of the 274 members contacted responded. Fifty-seven percent used LED units, 25% quartz tungsten halogen (QTH), and 1% plasma arc (missing: 17%). Thirty percent reported having access to a radiometer. Appropriate responses regarding the degree of conversion of composite and adhesive materials were given by 32% and 23% respectively, and 22% agreed that LED and QTH LCUs had comparable efficiency in polymerising composites. Thirty-three percent were aware that RBCs eluted substances that may have adverse local or systemic consequences. Fifty-eight percent stated that if polymerisation of RBC is slowed down, polymerisation stress will be lower, and 43% said that polymerisation shrinkage will be reduced if the degree of conversion is reduced. Knowledge (measured by appropriate responses to these questions) was not related to years since qualification (r=-0.05, n=168, p=0.53).
The study suggests that dentists' knowledge of curing RBC restorations and LCUs is poor. This indicates that there is a need for training and guidance in this aspect of primary dental care.
Unlabelled:
This laboratory study examined the effects of curing lights with different light intensities and changing flow rate on the increase in pulpal temperature during the light curing process and the rate of the subsequent decrease in temperature after the termination of light curing. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of the maxillary premolar. Metal tubes were inserted in the palatal and buccal root of the tooth, one for water inflow and the other for water outflow. The tubes were connected to a pump to control the flow rate. The water flow rate was set to 4.2 microl/minute, 28 microl/minute or 70 microl/minute. At each flow rate, the unprepared tooth was light cured from the buccal side 1 mm from the buccalsurface, using four different curing lights. The temperature data were recorded and stored on a computer every second for three minutes. The curing lights that were used were: Astralis 10 (QTH(high), Ivoclar Vivadent), Bluephase 16i (LED(conv), Ivoclar Vivadent) and two experimental LED-curing lights (LED(exp2000), LED(exp3000), Ivoclar Vivadent). The power densities were 1200 mW/cm2, 1600 mW/cm2, 2000 mW/cm2 and 3000 mW/cm2, respectively. The curing lights, LED(conv), LED(exp2000) and LED(exp3000) were activated for 60 seconds, and the QTH(high) was activated for 30 sec- onds. The maximum intrapulpal temperature (TM) and rate of temperature change at 30 seconds after turning off the light (S(30LO)) were analyzed by two-way ANOVA with a post-hoc Tukey test (p < 0.05). The influencing factors were the flow rates and curing lights.
Results:
The T(MAX) ranged from 41.0 degrees C to 53.5 degrees C. There was a difference between the curing lights (p < 0.05), with LED(exp3000) > LED(exp2000) > LED(conv) > QTH(high). There was no difference in T(MAX) between the different flow rates (p > 0.05). Both the curing lights and flow rates affected the SE(30LO) (p < 0.05). The S(30LO) was LED(exp3000) < LED(exp2000) > LEDon, , QTH(high) (p < 0.05). The S(30LO) at 70 microl/minutes was higher than at 4.2 pd/minutes and 28 microl/minutes (p < 0.05).
Clinical implication:
Because the increase in temperature is directly related to the light intensity and exposure time, curing devices with high power density (> 1200 mW/cm2) should only be activated for a short period of time (< 15 seconds) even in teeth without cavity preparation. The flow rate had only a negligible effect on the temperature increase.
O objetivo deste estudo foi mostrar que a potência da luz das unidades de fotopolimerização (LED) não é a única ou a propriedade mais importante para uma polimerização satisfatória de compósitos dentários. A distribuição regular e o ângulo de incidência dos raios de luz também são igualmente responsáveis por uma polimerização mais completa e profunda. Esta revisão de literatura mostra que avançamos o suficiente na potência da luz emitida pelos LEDs, mas no que diz respeito à regularidade e ângulo dos raios emitidos, ainda temos muito a avançar. Novos compósitos com cargas reflexivas e preocupações com a diferença de índice de refração entre as cargas e a matriz são importantes para melhorar essa polimerização, mas os LEDs com vários comprimentos de onda podem complicar ainda mais a distribuição regular dos raios de luz emitidos. Dispositivos com diferentes LEDs emitindo raios de luz com diferentes comprimentos de onda não distribuem essas ondas no modo regular. Portanto, parte da restauração pode estar sub polimerizada, tornando-se menos resistente aos esforços mastigatórios e à infiltração. O estudo também relembra propostas de avaliação científica dessa distribuição regular e conclui que os LEDs modernos emitem raios de luz com grande potência e irradiância, mas ainda são irregulares na distribuição dos raios de luz emitidos.Palavras-chave: fotopolimerização, conprimento de onda, irradiância, resina composta.PHOTOPOLIMERIZATION OF DENTAL COMPOSITES BEYOND THE LIGHT POWER EMITED BY LED LIGHT CURING UNITSABSTRACT: The objective of this study was to show that light power of light curing units (LCU) is not the only or the most important property for a satisfactory polymerization of dental composites. Regular distribution and angle of incidence of the light rays are also equally responsible for a fuller and deeper polymerization. This literature review shows that we advanced enough in the power of light emitted by LCUs, but as regards the regularity and angle of the emitted rays, we still have much to advance. New composites with reflective fillers and concerns about the difference of refractive index between the fillers and the matrixare important help to improve this polymerization, but LCUs with several wavelengths can further complicate the regular distribution of emitted light rays. Devices with different LEDs emitting light rays with different wavelengths does not distribute these waves in a regular mode. Therefore, part of the restoration can be under polymerized, becoming less resistant to masticatory efforts and infiltration as well. The study also recalls proposals for scientific evaluation of this regular distribution and concludes that modern LCUs emit light rays with great power and irradiance, but are still irregular in the distribution of emitted light rays.Keywords: photopolymerization, wavelength, Irradiance, composite.
SUMMARY This review article will help clinicians understand the important role of the light curing unit (LCU) in their offices. The importance of irradiance uniformity, spectral emission, monitoring the LCU, infection control methods, recommended light exposure times, and learning the correct light curing technique are reviewed. Additionally, the consequences of delivering too little or too much light energy, the concern over leachates from undercured resins, and the ocular hazards are discussed. Practical recommendations are provided to help clinicians improve their use of the LCU so that their patients can receive safe and potentially longer lasting resin restorations.
Delivering an inadequate amount of light to a light-cured resin will result in a resin that is inadequately cured. This study measured the radiant exposure that students delivered to a simulated restoration to determine if instruction with immediate feedback increased the amount of light they delivered. The amount of light (radiant exposure in J/cm(2)) delivered to a simulated restoration by sixty-three dental students using the same curing light for twenty seconds was recorded. The experiment was repeated after the students had been given detailed light-curing instructions together with immediate feedback using the MARCPS system. Initially, the students delivered between 1.4 and 17.5 J/cm(2) (mean±SD: 9.8±3.5 J/cm(2)). After receiving instructions and feedback on their light-curing technique, they delivered between 6.7 J/cm(2) and 17.8 J/cm(2) (mean±SD: 13.2±3.3 J/cm(2)). ANOVA and Fisher's post hoc multiple comparison tests showed that providing immediate feedback on the students' light-curing technique made a significant improvement in the radiant exposure they delivered (p<0.05). It was concluded that many dental students in this study were not using the curing light properly. After the students had received one session of additional instruction and immediate feedback using the MARC-PS, they delivered 35 percent more light energy to the same simulated restoration. Students who were closer to graduation showed a greater improvement in their light-curing technique (p=0.0091).
This study compared monomer conversion (DC), the per cent linear polymerization shrinkage (%LS), the wall-to-wall contraction pattern (per cent of peripheral opening, %DM, and maximal marginal gap, MG) and depth of cure (DOC), of a hybrid resin composite (Spectrum TPH) exposed to different types of light-curing units and exposure modes (Virtuoso-PAC, Elipar TriLight-QTH, and FreeLight-LED). The QTH and LED units were used in two curing modes: the exponential ramp and the continuous output modes. Monomer conversion was investigated by micro Multiple Internal Reflection (MIR)-Fourier-transform infrared (FTIR) spectroscopy and %LS was measured by the deflective disc method. The wall-to-wall contraction method used a cylindrical cavity model in extracted human teeth. The per cent debonded margins relative to the cavity periphery (%DM) and the width of maximum gap (MG) was evaluated. The DOC was determined using Vickers microhardness measurements (200 g load, 20 s) at the top surface (H0), at 2 mm (H2) and at 4 mm (H4) depths, and the results expressed as H2/H0 and H4/H0 ratios. Significantly lower %DC and %LS values were provided by PAC and LED units. No differences were found in %DM among the curing units and PAC exhibited the highest MG. No significant differences were noted among light-curing groups in terms of H2/H0 microhardness values. The QTH, operated in exponential mode, resulted in the highest H4/H0 value. The exponential mode of the QTH demonstrated superior performance for the total of the characteristics evaluated.
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