Effect of endodontic retreatment on the bond strength of resin cements to root canal dentin.

PURPOSE: To evaluate the effect of endodontic retreatment on the bond strength of different cementation techniques (self-adhesive and conventional resin cement) through the push-out mechanical testing and the penetrability of resin cements to root dentin. METHODS: 60 human teeth with single oval-shaped canals were used (n=15) : G1 - Endodontic treatment and cementation with RelyX ARC (ETA); G2 - Endodontic treatment and cementation with U200 (ETU); G3 - Endodontic retreatment and cementation with RelyX ARC (ERA); G4 - Endodontic retreatment and cementation with U200 (ERU). The groups with conventional endodontic treatment were filled with AH plus (ETA and ETU), while the groups that were submitted to endodontic retreatment were initially filled with Endofill and afterwards with AH Plus. Each radicular third (cervical, middle, and apical, of each tooth) was submitted to push-out bond strength testing, followed by evaluation with confocal laser microscopy to determine the penetration of the resin cements, and scanning electron microscopy was used to evaluate the failure mode. The parametric data were evaluated by two-way ANOVA and Tukey tests, and non-parametric data by Kruskal-Wallis and Dunn tests (α< 0.05). RESULTS: The ETA group had higher bond strength values to intra-radicular dentin than the other groups in all root thirds (P< 0.05). Endodontic retreatment had a negative impact on the penetration and push-out bond strength of RelyX ARC and U200 cement, regardless of the analyzed radicular third. CLINICAL SIGNIFICANCE: The bond strength between fiber post and root dentin can be affected by several factors, such as technical failure, cementation technique, pretreatment of the dentin, type of post and adaptation. The endodontic retreatment interferes negatively on the bond strength and penetrability of RelyX ARC and U200 cements to dentin, regardless of the analyzed radicular third. Therefore, the endodontic retreatment might have an adverse effect due to over preparation and aggression to the root canal.

Effect of the Curing Temperature of Dental Composites evaluated with a Fluorescent Dye.

AIM: With the development of the light-emitting diode (LED) to photo-activate composite resin, greater intensities could be reached without greater elevation of temperature in the mass of the composite resin and in the dental structure arisen from the irradiance in comparison to halogen equipments. This new scenario created a necessity to investigate the influence of temperature over the composite polymerization. MATERIALS AND METHODS: Several curing temperatures (Tcure- 0, 25, 50, 75, and 100°C) were used to polymerize a composite resin (Filtek Z250, 3M ESPE) for 40 and 60 s, using the halogen equipment Gnatus Optilight Digital (halogen) and two LEDs that use a new technology to assembly the diodes: LEC 1000 and bright LEC (MM Optics) (LED 1 and LED 2 respectively). The influence of curing temperature, added by the other variables studied, was evaluated using a methodology developed and improved at IFSC/USP, in which the penetration of a fluorescent dye in the body of the photopolymerized composite resin was quantified using fluorescence spectroscopy. RESULTS: According to the final data submitted to an analysis of variance, the presence of two groups of results could be verified: Between 0 and 25°C, both had a great percentage of the dye penetration compared with other Tcure with a variation in penetration from 69.26 ± 8.19% to 90.99 ± 3.38%. In this analysis, the effects of time and temperature were highly notable (p < 0.05) and the lesser value of dye penetration took place at 60 s of photoactivation This penetration was, in average, smaller with the Tcure of 25°C. The results showed that there was an interaction between the equipment and time and between time and temperature; the other group is regarding the Tcure was from 50, 75, and 100°C, despite the p = 0.05, the effect of temperature was notable. The penetration of the dye ranged from 8.87 ± 3.55 to 39.47 ± 8.9%. The effects of equipment and time were highly notable. The penetration with the time of 60 s was in average smaller. Except with the equipment LED 1, the percentages of the dye penetration were greater with the Tcure of 100°C. The smallest average was the Tcure of 50°C and 60 s of photoactivation. CONCLUSION: Based on the available data regarding the influence of curing temperature on the polymerization process of composite resins, was possible to concluded that small increments of heat increased the degree of conversion. We can assume that the energy supply through the generation of heat by the photopolymerizing devices can function as a heating medium for the reagent system by reducing its viscosity and increasing the mobility and agitation of its components. CLINICAL SIGNIFICANCE: The dentist must be aware of the effects that exist between the activation devices on the light output and their heat transmission to the composite and the tooth itself. This heat transmission might create a polymer with better characteristics.

Influência dos hábitos de sucção na manifestação de dor têmporo-mandibular: revisão sistemática / Influence of oral sucking habits on symptoms of temporomandibular dysfunction: a systematic review

Este estudo teve como objetivo realizar uma revisão sistemática da literatura para avaliar os efeitos dos hábitos parafuncionais de sucção sobre a ATM e estruturas adjacentes em crianças. Os artigos incluídos foram identificados por meio de pesquisas bibliográficas da Bireme, Pubmed, ClinicalTrials.gov, The National Research Register e Pro-Quest Dissertation Abstracts and Thesis, usando os termos de busca temporomandibular joint, sucking behavior and fingersucking. As pesquisas sobre os hábitos atuais ou anteriores de chupar o dedo e/ou uso de mamadeiras e chupetas e a presença de dor na ATM com crianças até 12 anos foram incluídas. Oito estudos foram selecionados, e 4 apresentaram uma associação, mas sem significância estatística. Os achados científicos demonstram uma associação baixa ou ausente de DTM com hábitos de sucção parafuncionais.

Objective: To assess the attitudes and knowledge about hepatitis by scholars and dental practitioners from Recife and its metropolitan region. Method: The research protocol was submitted and approved by the Ethics and Human Research Committee of the Federal University of Pernambuco. There were included 230 undergraduate students in dentistry and 104 dentists who exercise their professional activity in Recife and its Metropolitan Region. They signed a consent form and answered a questionnaire, the evaluative instrument, with objective questions about biosafety, transmission of hepatitis and sexually transmitted diseases. Results: About the types of hepatitis 133 (57.8%) students and 61 (58.7%) professionals claimed to know the types A, B and C. Concerning transmission 31 (13.5%) students and 25 (24.0%) professionals said that the main route of transmission were sexual and bloodstream respectively. Relating to imunization 221 (96.1%) students and 99 (95.2%) professionals reported that have been vaccinated against hepatitis B, however, only 126 (54.8%) students and 55 (52.9%) professionals have followed the immunization's schema. Regarding the cleaning of the office equipment, 18.7% of the students replied that they do not know who does it. 56.7% of professionals said that it was performed with alcohol 70 ° GL.Conclusions: The findings indicate that there is a concern for biosafety but the knowledge about the forms of hepatitis transmission and biosecurity measures need to be better settled.

Nd:YAG laser irradiation of etched/unetched dentin through an uncured two-step etch-and-rinse adhesive and its effect on microtensile bond strength.

PURPOSE: To evaluate whether Nd:YAG laser irradiation of etched and unetched dentin through an uncured adhesive affected the microtensile bond strength (µTBS). MATERIALS AND METHODS: Flat dentin surfaces were created in 19 extracted human third molars. Adper Single Bond (SB) adhesive was applied over etched (groups 1 to 3) or unetched dentin (groups 4 to 6). The dentin was then irradiated with a Nd:YAG laser through the uncured adhesive, using 0.75 or 1 W power settings, except for the control groups (groups 1 and 4). The adhesive was light cured and composite crowns were built up. After 24 h, the teeth were sectioned into beams, with cross-sectional areas of 0.49 mm2, and were stressed under tension. Data were statistically analyzed using two-way ANOVA and Tukey's test (α = 5%). Dentin surfaces of fractured specimens and the interfaces of untested beams were observed under scanning electron microscopy (SEM). RESULTS: Acid etching, laser irradiation, and their interaction significantly affected bonding (p < 0.05). Laser irradiation did not improve bonding of etched dentin to resin (p > 0.05). However, higher µTBS means were found on unetched lased dentin (groups 5 and 6), but only in comparison to group 4, where neither lasing nor etching was performed. Groups 4 to 6 showed the lowest µTBS means among all groups tested (p < 0.05). Laser irradiation did not change the characteristics of the hybrid layers created, while solidification globules were observed on lased dentin surfaces under SEM. CONCLUSION: Laser irradiation of dentin through the uncured adhesive did not significantly improve the µTBS in comparison to the suggested manufacturer's technique.

Influence of different dentin etching times and concentrations and air-abrasion technique on dentin microtensile bond strength.

PURPOSE: To determine the influence of different dentin treatments on the microtensile bond strengths of adhesive resins to dentin. METHODS: Fifteen human molars were ground to 600-grit to obtain flat root-dentin surfaces. Five different dentin treatments were evaluated: Group 1--10% phosphoric acid for 30 seconds; Group 2--37% phosphoric acid for 15 seconds; Group 3--air-abrasion for 10 seconds followed by 10% phosphoric acid for 30 seconds; Group 4--air-abasion for 10 seconds followed by 37% phosphoric acid for 15 seconds. The dental adhesive (OptiBond Solo Plus) was applied according to manufacturer's instructions and followed by composite (Z100) application to provide sufficient bulk for microtensile bond testing. All samples were placed in distilled water for 24 hours at 37 degrees C, thermocycled for 500 cycles in distilled water at 10 degrees C and 50 degrees C, and serially sliced perpendicular to the adhesive surface and subjected to tensile forces (0.5 mm/minute). Additional samples were prepared for SEM to observe the adhesive interface. RESULTS: Group 2 exhibited significantly (P < 0.05) lower bond strength values than all other treatments. The bond strengths of the different conditions were (in MPa): Group 1: 43.0 +/- 16.1; Group 2: 29.2 +/- 8.3; Group 3: 48.1 +/- 14.2; Group 4: 41.0 +/- 9.3. The dentin treated with phosphoric acid 37% for 15 seconds showed the lowest values of microtensile bond strength. The results obtained with Groups 1, 3 and 4 were statistically similar.