Effect of temperature on composite polymerization stress and degree of conversion.

OBJECTIVE: To test the following hypotheses: (1) degree of conversion (DC) and polymerization stress (PS) increase with composite temperature (2) reduced light-exposure applied to pre-heated composites produces similar conversion as room temperature with decreased PS. METHODS: Composite specimens (diameter: 5mm, height: 2mm) were tested isothermally at 22°C (control), 40°C, and 60°C using light-exposures of 5 or 20s (control). DC was accessed 5min after light initiation by FTIR at the specimen bottom surface. Maximum and final PS were determined, also isothermally, for 5min on a universal testing machine. Non-isothermal stress was also measured with composite maintained at 22°C or 60°C, and irradiated for 20s at 30°C. Data were analyzed using two-way ANOVA/Tukey and Student's t-test (α=5%). RESULTS: Both DC and isothermal maximum stress increased with temperature (p<0.001) and exposure duration (p<0.001). Isothermal maximum/final stress (MPa) were 3.4±2.0b/3.4±2.0A (22°C), 3.7±1.5b/3.6±1.4A (40°C) and 5.1±2.0a/4.0±1.6A (60°C). Conversion values (%) were 39.2±7.1c (22°C), 50.0±5.4b (40°C) and 58.5±5.7a (60°C). The reduction of light exposure duration (from 20s to 5s) with pre-heated composite yielded the same or significantly higher conversion (%) than control (22°C, 20s/control: 45.4±1.8b, 40°C, 5s s: 45.1±0.5b, 60°C, 5s s: 53.7±2.7a, p<0.01). Non-Isothermal conditions showed significantly higher stress for 60°C than 22°C (in MPa, maximum: 4.7±0.5 and 3.7±0.4, final: 4.6±0.6 and 3.6±0.4, respectively). CLINICAL SIGNIFICANCE: Increasing composite temperature allows for reduced exposure duration and lower polymerization stress (both maximum and final) while maintaining or increasing degree of conversion.

Observational: prospective study of indirect pulp treatment in primary molars using resin-modified glass ionomer and 2% chlorhexidine gluconate: a 12-month Follow-up.

PURPOSE: This study's purpose was to determine the efficacy of indirect pulp treatment (IPT) in primary molars when using 2% chlorhexidine gluconate disinfecting solution and resin-modified glass ionomer (RMGI) liner after 12 months. METHODS: Three- to 10-year-old subjects with deep carious lesions who met selection criteria participated. Infected dentin was removed using a caries detector, and residual affected dentin was left on the pulpal floor to prevent pulp exposure. A 2% chlorhexidine gluconate solution and a RMGI liner were placed. Teeth were restored with composite or full-coverage (stainless steel crown [SSC]) restorations. Follow-up evaluations at 3, 6, and 12 months included clinical, radiographic, and photographic assessments. RESULTS: A total of 60 teeth were treated. Treatment was successful in 50/50 (100%), 41/42 (∼98%), and 31/32 (∼97%) teeth at the 3-, 6-, and 12-month follow-up visits, respectively. Failures included one at 6 months in a primary second molar with a composite restoration and another at 12 months in a primary first molar with a SSC. CONCLUSIONS: Indirect pulp treatment is effective in primary teeth, although appropriate case selection and an adequate marginal seal are essential for a successful outcome. Further prospective studies are needed to expand the body of evidence that clinicians use to justify decisions on clinical care.

Identification and long term stability of DNA captured on a dental impression wafer.

PURPOSE: The purpose of this study was to determine the quantity and quality of DNA extracted from a dental bite impression wafer immediately after impression and after 12 months of home storage. The authors' hypothesis was that the wafer would retain sufficient DNA with appropriate genetic markers to make an identification match. METHODS: Two impression wafers (Toothprints(®) brand) were administered to 100 3- to 26-year-olds. A cotton swab was used as a control. DNA from wafers stored for 12 months at home were compared to DNA collected at time 0 and compared to swabs at specific sites to determine quality and accuracy. The amount of DNA captured and recovered was analyzed using MagAttract technology and a quantitative real-time polymerase chain reaction. Capillary gel electrophoresis was performed to determine the quality of the DNA profiles obtained from the wafers vs those generated from the swabs of each subject. RESULTS: Average DNA concentration was: 480 pg/µL (wafer at time 0); 392 pg/µL (wafer after 12 months kept by subjects); and 1,041 pg/µL (buccal swab). Sufficient DNA for human identification was recovered from all sets of wafers, producing clear DNA profiles and accurate matches to buccal swabs. No inhibitors were found that could interfere with DNA profiling. CONCLUSIONS: Toothprints® impression wafers can be useful for DNA collection and child identification. After 12 months, the wafer was still usable for DNA capture and identification match.

Oral health findings in athletes with intellectual disabilities at the NYC Special Olympics.

This study collected data to describe the oral health in Special Olympics athletes with intellectual disabilities from New York City, using the standardized Special Olympics, Special Smiles protocol. A total of 664 self-selected athletes with intellectual disabilities were screened between 2005 and 2008. A standardized form was used for data collection. Screenings were performed using available light or flashlight, tongue depressor, and disposable mirror. Oral hygiene, reports of oral pain, untreated caries, missing and filled teeth were recorded. The majority of the athletes were 20 years of age or older (52%). Of the examined athletes, 9% reported oral pain, 8% needed urgent care, 28% had untreated caries, 60% had filled teeth, and 32% had signs of gingival disease. Mouthguards were recommended for 26% of athletes. Our findings offer an initial evaluation of the oral health of Special Olympics athletes with intellectual disabilities in New York City. Results showed high preventive and restorative oral health needs in the Special Olympics population.

Use of mobile electronic devices as educational tool in pediatric community outreach.

The introduction of mobile electronic devices, as opposed to paper forms, in pediatric outreach programs of the New York University College of Dentistry is discussed. Since 2007, students have been receiving training on how to operate a personal digital assistant (PDA) and use it in community outreach for non-invasive oral-facial screenings and patient education. The shift from using paper forms to electronic media had a positive impact among the academic community, as it resulted in saving time and reducing the possibility of data collection errors. It may represent a significant improvement in data collection and patient education; and it provides an opportunity to enhance research and quality assessment.

In vivo temperature measurement: tooth preparation and restoration with preheated resin composite.

STATEMENT OF THE PROBLEM: Composite preheating has shown to improve material physical properties in vitro, but no data exist on the use of this technique in vivo during placement. PURPOSE: The study aims to measure in vivo prepared tooth surface temperature during a restorative procedure using resin composite either at room temperature (23.6°C) or preheated to 54.7°C in a commercial compule heating device set to heat at 60°C. METHODS: Class I preparations (N=3) were made on a patient requiring multiple posterior restorations. A probe containing two thermocouples was used to record temperature values at the tooth pulpal floor and 2mm higher (top of the tooth preparation/restoration) after tooth preparation (prep), acid etching (etch), placement and curing of a bonding agent (BA), and during placement of composite used at room temperature (RT) or preheated in a commercial device (Calset(TM) , AdDent Inc., Danbury, CT, USA) set to 60°C. Data were compared with two-way analysis of variance, Tukey-Kramer post hoc test (α=0.05). RESULTS: No significant difference in pulpal floor temperature existed between prep (27.8°±1.3°C) and etch (26.3°±1.3°C), which were significantly lower than BA (30.5°±1.3°C) (p=0.0001). Immediate placement of preheated composite resulted in significantly higher pulpal floor (36.2°±1.9°C) (p=0.0025) and top composite temperatures (38.4°±2.2°C) (p=0.0034) than RT values (30.4°±2.2°C and 29.6°±0.9°C, respectively). CONCLUSIONS: In vivo use and placement of preheated resin composite resulted in temperature increase of 6° to 8°C than room temperature material. These values, however, were much lower than expected. CLINICAL SIGNIFICANCE: Although having many potential benefits, composite preheating may not be as clinically effective in delivering resin of predetermined temperature at the time of cure as laboratory experiments would suggest. Despite only moderate composite temperature increase over use of room temperature material, preheating still provides advantages in terms of ease of handling and placement.

Nutrition and oral health considerations in children with special health care needs: implications for oral health care providers.

Children with special health care needs are at increased risk for oral diseases. The purpose of this article was to discuss: nutritional and oral health factors routinely observed in most chronic childhood disorders; dietary modifications associated with select systemic disorders and how they may impact oral health in children; and the following factors common to chronic disorders associated with diet modifications-decreased appetite and increased nutritional risk; frequency of food intake; parental overindulgence; long-term use of cariogenic medications; and xerostomia. Characteristics of childhood disorders that require dietary modifications (congenital heart disease, cystic fibrosis, cancer, AIDS/HIV, diabetes mellitus, and phenylketonuria) are summarized. In addition, healthy dietary modifications and oral health recommendations are suggested. Implementation of these recommendations can assist the dentist and dental team as they join physicians and nutritionists in delivering the best possible care to children with special health care needs.

Public-private collaboration to improve oral health status of children enrolled in Head Start in New York City.

A comprehensive oral health care program for Head Start children in New York City is described. Head Start is a federally funded pre-school program for low-income families and their children. It provides activities that help children grow mentally, socially, emotionally and physically. In 1994, a public-private partnership was created between New York Administration for Children's Services and New York University College of Dentistry. The program consists of periodic visits to different Head Start centers by a dental team composed of pediatric dentists, residents, hygienists and students. At the center, the team provides diagnostic and preventive services to children and oral health education to children, parents and staff. Referrals are then made to the College of Dentistry or to a community provider for treatment and follow-up. Free transportation is provided between Head Start centers and the college clinic. Over 13 years, 25,000 children have received diagnostic, preventive and treatment services.

Microtensile bond strength of adhesive systems to dentin with or without application of an intermediate flowable resin layer.

This study evaluated the effect of flowable composite resin application on the microtensile bond strength (microTBS) of adhesive systems to dentin. Occlusal surfaces of human third molars were ground to obtain flat dentin surfaces. The crown of each tooth was sectioned occluso-gingivally into four quarters with a water-cooled diamond saw. One of the following adhesive systems was applied to dentin surface in each quarter of the same tooth, following manufacturers' instructions: Scotchbond Multipurpose, Single Bond Adper Prompt and Clearfil SE Bond. Experimental and control groups received the same treatment, except for the fact that a layer of flowable composite (Filtek Flow) was placed and light-cured on top of the adhesive layer in the specimens of the experimental groups. Resin composite (Filtek Z250) crown buildups were then made on the bonded surfaces and incrementally light-cured for 20 s. The restored teeth were stored in water at 37 degrees C for 24 h. Each tooth quarter was serially cut in a longitudinal direction in order to obtain several bonded sticks (0.9-mm(2) in cross-section). Maximal microtensile stress (in MPa) at failure was recorded using a universal testing machine. Data were analyzed by two-way ANOVA and Tukey's test at 5% significance level. Placement of a low-viscosity resin to the hybridized dentin increased the microTBS for all tested adhesive systems. However, such increase was significant only for Clearfil SE Bond (p<0.05). When the restorations were placed without low-viscosity resin, Clearfil SE Bond presented higher microTBS than Adper Prompt (p<0.05). For the groups treated with flowable composite, Clearfil SE Bond produced the highest microTBS means to dentin. In conclusion, the effect of the addition of an intermediate flowable composite layer on microTBS to dentin was material-dependent and resulted in an increased adhesion for all tested materials, though with significance only for Clearfil SE Bond.

Influence of irradiant energy on degree of conversion, polymerization rate and shrinkage stress in an experimental resin composite system.

OBJECTIVE: This study evaluated the degree of conversion (DC), maximum rate of cure (Rpmax), and polymerization stress (PS) developed by an experimental dental composite subjected to different irradiant energies (3, 6, 12, 24, or 48 J/cm2) under constant irradiance (500 mW/cm2). METHODS: DC and Rpmax were monitored for 10 min on the bottom surface of 2-mm thick disks and on 150-microm thick films (representing the top of the specimen) using ATR-FTIR. PS was monitored for 10 min in 2-mm thick disks bonded to two glass rods (Ø=5mm) attached to a universal testing machine. One-way ANOVA/Tukey tests were used and differences in DC and R(p)(max) between top and bottom surfaces were examined using Student's t-test. Statistical testing was performed at a pre-set alpha of 0.05. RESULTS: For a given surface, DC showed differences among all groups, except at the top between 24 and 48 J/cm2. Rpmax was similar among all groups at the same surface and statistically higher at the top surface. PS also showed significant differences among all groups. Data for 48 J/cm2 were not obtained due to specimen failure at the glass/composite interface. SIGNIFICANCE: Increases in irradiant exposure led to significant increases in DC and PS, but had no effect on Rpmax.

Degree of conversion and mechanical properties of a BisGMA:TEGDMA composite as a function of the applied radiant exposure.

OBJECTIVE: Verify the influence of radiant exposure (H) on composite degree of conversion (DC) and mechanical properties. METHODS: Composite was photoactivated with 3, 6, 12, 24, or 48 J/cm(2). Properties were measured after 48-h dry storage at room temperature. DC was determined on the flat surfaces of 6 mm x 2 mm disk-shaped specimens using FTIR. Flexural strength (FS) and modulus (FM) were accessed by three-point bending. Knoop microhardness number (KHN) was measured on fragments of FS specimens. Data were analyzed by one-way ANOVA/Tukey test, Student's t-test, and regression analysis. RESULTS: DC/top between 6 and 12 J/cm(2) and between 24 and 48 J/cm(2) were not statistically different. No differences between DC/top and bottom were detected. DC/bottom, FM, and KHN/top showed significant differences among all H levels. FS did not vary between 12 and 24 J/cm(2) and between 24 and 48 J/cm(2). KHN/bottom at 3 and 6 J/cm(2) was similar. KHN between top and bottom was different up to 12 J/cm(2). Regression analyses having H as independent variable showed a plateau region above 24 J/cm(2). KHN increased exponentially (top) or linearly (bottom) with DC. FS and FM increased almost linearly with DC/bottom up to 55% conversion. CONCLUSIONS: DC and mechanical properties increased with radiant exposure. Variables leveled off at high H levels.

Microtensile bond strength of adhesive systems to dentin with or without application of an intermediate flowable resin layer

This study evaluated the effect of flowable composite resin application on the microtensile bond strength (muTBS) of adhesive systems to dentin. Occlusal surfaces of human third molars were ground to obtain flat dentin surfaces. The crown of each tooth was sectioned occluso-gingivally into four quarters with a water-cooled diamond saw. One of the following adhesive systems was applied to dentin surface in each quarter of the same tooth, following manufacturers' instructions: Scotchbond Multipurpose, Single Bond Adper Prompt and Clearfil SE Bond. Experimental and control groups received the same treatment, except for the fact that a layer of flowable composite (Filtek Flow) was placed and light-cured on top of the adhesive layer in the specimens of the experimental groups. Resin composite (Filtek Z250) crown buildups were then made on the bonded surfaces and incrementally light-cured for 20 s. The restored teeth were stored in water at 37ºC for 24 h. Each tooth quarter was serially cut in a longitudinal direction in order to obtain several bonded sticks (0.9-mm² in cross-section). Maximal microtensile stress (in MPa) at failure was recorded using a universal testing machine. Data were analyzed by two-way ANOVA and Tukey's test at 5 percent significance level. Placement of a low-viscosity resin to the hybridized dentin increased the muTBS for all tested adhesive systems. However, such increase was significant only for Clearfil SE Bond (p<0.05). When the restorations were placed without low-viscosity resin, Clearfil SE Bond presented higher muTBS than Adper Prompt (p<0.05). For the groups treated with flowable composite, Clearfil SE Bond produced the highest muTBS means to dentin. In conclusion, the effect of the addition of an intermediate flowable composite layer on muTBS to dentin was material-dependent and resulted in an increased adhesion for all tested materials, though with significance only for Clearfil SE Bond.

Este estudo avaliou o efeito da aplicação de uma resina flow na resistência de união (RU) (microtração) de sistemas adesivos à dentina. Superfícies oclusais de terceiros molares humanos foram abrasionadas para formar superfícies dentinárias planificadas. As coroas foram seccionadas no sentido ocluso-gengival em quatro partes de tamanhos similares com disco diamantado sob refrigeração. Os sistemas adesivos (Scotchbond Multipurpose; Single Bond; Adper Prompt e Clearfil SE Bond) foram aplicados nas superfícies dentinárias, de acordo com as instruções dos fabricantes, sendo cada um deles em uma das quatro partes de um mesmo dente. Os grupos experimentais e controle receberam o mesmo tratamento, porém a resina flow (Filtek Flow) foi aplicada e fotoativada sobre os sistemas adesivos nos espécimes dos grupos experimentais. Um bloco de compósito (Filtek Z250) foi confeccionado em incrementos sobre as superfícies tratadas com o sistema adesivo e fotoativado por 20 s. Os dentes restaurados foram armazenados em água a 37ºC por 24 h e seccionados longitudinalmente para obtenção de espécimes com formato de paralelepípedo, com 0,9 mm² na área de união. O ensaio de tração foi realizado em máquina universal de ensaios e os valores de RU foram expressos em MPa. Os dados foram analisados pela ANOVA (dois fatores) e teste de Tukey (5 por cento). A aplicação da resina flow na dentina previamente hibridizada aumentou a RU para todos os sistemas adesivos, entretanto, foi estatisticamente significativa somente para o adesivo Clearfil SE Bond (p<0,05). Quando as restaurações foram confeccionadas sem a resina de baixa viscosidade, o Clearfil SE Bond obteve maior valor de RU que o adesivo Adper Prompt (p<0,05). Para os grupos com a resina flow, o Clearfil SE Bond resultou no maior valor médio de RU à dentina. Conclui-se que o efeito da aplicação da resina flow foi depende do sistema adesivo utilizado e indicou um aumento na RU para todos os sistemas adesivos...

Effect of composite temperature on in vitro intrapulpal temperature rise.

OBJECTIVES: To measure in vitro intrapulpal temperature when placing and restoring with either room-temperature or pre-heated (54 and 60 degrees C) composite. METHODS: A K-type thermocouple was placed in the pulpal chamber of an extracted, human bifurcated upper premolar which had a Class V preparation (1 mm remaining dentin thickness) on the facial surface. Tooth roots were immersed in a thermostatically controlled water bath and perfused with water at 1.25 microl/min to simulate physiological circulation in the pulp chamber. The thermocouple was connected to an analog-to-digital converter. The preparation was filled using composite either at room-temperature, or pre-heated to 54 or 60 degrees C with a commercial compule heater (Calset), using standard clinical procedures by one person while continuously monitoring intrapulpal temperature (n=5). Temperature rise over baseline values were determined at various stages during the restoration process: composite placement, contouring, prior to light-curing, and immediately after light-curing (20s, Optilux 501). At each measurement interval, intrapulpal temperature values were compared using ANOVA and the Tukey-Kramer post hoc test (alpha=0.05). RESULTS: Significant differences were found in intrapulpal temperature when comparing pre-heated and room-temperature composite treatments with respect to baseline among the stages of the restorative process. However, the extent of this increase with heated composite was only 0.8 degrees C. A 5 degrees C intrapulpal temperature rise was seen for all groups during photopolymerization. SIGNIFICANCE: Use of pre-heated composite only mildly increased intrapulpal temperature values when compared to composite delivered at room-temperature in an in vitro test environment. The largest temperature change occurred with application of the curing light.

Clinically relevant issues related to preheating composites.

STATEMENT OF THE PROBLEM: Issues regarding the use of composite preheating need to be investigated so that the clinician will better understand the variables associated with this method. PURPOSE: To examine the multiple aspects of use of a commercial composite preheating device (Calset, AdDent Inc., Danbury, CT, USA). MATERIALS AND METHODS: Temperature values of three heating units and composite compules were obtained using a K-type thermocouple and were recorded digitally in real time. The following parameters were measured: maximum heater and composite temperature and its stability upon storage, composite temperature change when removed from the heater and injected, the effect of delivery system on ejected composite temperature, and the effect of repeated and extended preheating on composite monomer conversion (using infrared spectroscopy). Monomer conversion was measured after repeated composite cycling (from room temperature [RT] to 60 degrees C, 10x) or extended preheating (24 hours at 60 degrees C), and values were compared with composite maintained at RT (control group). Among test parameters, data (N=5 for each parameter) were analyzed using Student's t-test, analysis of variance, and the Tukey-Kramer post-hoc test where appropriate (alpha=0.05). RESULTS/CONCLUSIONS: Two of the three tested units achieved the stated preset temperatures. Composite attained temperature values close to the heating unit. Composite temperature drop upon removal from the heater was dramatic: within 2 minutes a 50% temperature drop was noted. Heating the compule while preloaded in the syringe provided higher delivery temperatures than heating the compule separately (p < 0.00). Optimum results were achieved when preheated composite was dispensed and used as quickly as possible. Neither repeated nor extended preheating of composite significantly affected monomer conversion. CLINICAL SIGNIFICANCE: Preheating composite has potential benefits, but should be used with knowledge of its limitations. Reheating of unused composite does not affect its degree of conversion, thus decreasing material waste. Heating of the composite preloaded in the delivery syringe enhances the temperature of extruded composite.

Effects of Nd:YAG laser on enamel microhardness and dental plaque composition: an in situ study.

OBJECTIVE: This study evaluated Knoop microhardness (KHN) and dental plaque composition of human enamel irradiated with Nd:YAG laser and subjected to in situ cariogenic challenge. BACKGROUND DATA: Although in vitro studies have shown that Nd:YAG laser irradiation results in a reduction of enamel mineral loss after acid challenge, this hypothesis has not been tested using an in situ caries model. METHODS: Acrylic devices containing lased and non-lased human enamel slabs were used for 28 days by eight subjects highly colonized by S. mutans. Devices were immersed in a sucrose solution (20%) eight times daily in order to better simulate the cariogenic challenge. RESULTS: After the experimental period, no differences in dental plaque composition were observed between lased and non-lased enamel slabs indicating that all slabs were exposed to equivalent cariogenic challenges. Cross sections of enamel slabs were then measured for Knoop microhardness at 10, 20, 40, 60, 80, 120, and 180 microm in depth from the outer exposed surface. Un-lased enamel slabs not subjected to the in situ cariogenic challenge were also used as control. Enamel slabs from the two in situ groups exhibited lower hardness when compared to control. Lased enamel showed higher hardness values up to 60 microm in depth than the un-lased enamel exposed to in situ cariogenic challenge. CONCLUSION: The results suggest that the irradiation of Nd:YAG laser of human enamel appears to be effective for increasing enamel hardness and thus decreasing the effect of acid attack.

SEM evaluation of contemporary self-etching primers applied to ground and unground enamel.

PURPOSE: This study evaluated the etching effect of self-etching priming agents applied to intact and ground enamel. MATERIALS AND METHODS: Thirty-two human molars were used. Each tooth was divided into two halves. The buccal or lingual mid-coronal surface of 32 half-teeth was ground with 600-grit silicon carbide paper. The other half-teeth were left intact (control). Teeth were treated with Clearfil SE Bond (SE), Prompt L-Pop (PLP) or Adper (AD). Those in the control group were etched with 35% phosphoric acid. The etching effect of such systems on enamel surfaces was assessed by three different approaches using scanning electron microscopy: 1) in situ or direct morphological examination of the etched enamel; 2) indirect morphological examination, that is, evaluation of the etching pattern left on resin reproductions; 3) adhesive interface examination. RESULTS: SE exhibited the least aggressive dissolution of the intact and ground enamel, with many sites of the intact enamel remaining completely unetched. SE monomer infiltration into etched enamel was restricted to the superficial layer. PLP and AD produced equivalent etching patterns on intact and ground enamel, which resemble that produced by the phosphoric acid control group. PLP and AD monomer penetration extended along the porous subsurface enamel layer. CONCLUSION: SE produced mild morphological changes on intact and ground enamel surface, resulting in a very superficial resin infiltration particularly into intact enamel. No differences were evident among the etching and resin infiltration pattern produced by both all-in-one self-etching adhesives, PLP and AD, and the phosphoric acid system.

Avaliação in vitro e in vivo da resina composta pré-aquecida em relação à cinética de polimerização / In vitro and in vivo appraisal of pre-heated resin composite with relation to polymerization kinetics

O objetivo do trabalho foi investigar múltiplos aspectos relacionados ao preaquecimento da resina composta anterior à fotoativação: o grau de conversão e a cinética da polimerização em função da temperatura de polimerização, tempo de fotoativação e profundidade; o desempenho da fonte aquecedora (temperatura máxima, estabilidade térmica do aparelho e variações de temperatura ao préaquecer compules) e aspectos clínicos (o efeito de ciclos de pré-aquecimento repetidos e prolongados sobre o grau de conversão, a variação da temperatura intrapulpar in vitro e a variação da temperatura in vivo ao usar resina composta préaquecida ou a temperatura ambiente. A conversão de monômeros e os parâmetros de cinética foram determinados através de FTIR-ATR. Os espécimes foram fotoativados por 5, 10, 20 ou 40s entre 3o e 60oC. Foram calculados o grau de conversão em tempo real, a taxa máxima de conversão, o tempo em que ocorreu a taxa máxima, e a conversão na taxa máxima. Os dados foram tratados por análise de variância, teste-t e análise de regressão (p ≤ 0,05). O desempenho do dispositivo aquecedor foi medido monitorando-se a mudança de temperatura em tempo real com o auxílio de um termopar tipo-k conectado a um conversor analógico-digital...

Antibacterial and conventional self-etching primer system: morphological evaluation of intact primary enamel.

The aim of this study was to analyze the etching effect of a new dental adhesive system that uses an antibacterial and self-etching primer agent. Non-carious primary human molars were divided into three groups: 35% phosphoric acid etching (3M-ESPE), self-etching primer (Clearfil SE Bond--Kuraray) and antibacterial self-etching primer (ABF experimental system--Kuraray) for SEM evaluation of surface, resin replicas and interface. Both self-etching primers produced shallow grooves and no defined etching morphologies. Phosphoric acid produced definite etching patterns at the enamel surface.