77 research outputs found
sj-pdf-1-jdr-10.1177_00220345211061736 – Supplemental material for Triacrylamide-Based Adhesives Stabilize Bonds in Physiologic Conditions
No full textSupplemental material, sj-pdf-1-jdr-10.1177_00220345211061736 for Triacrylamide-Based Adhesives Stabilize Bonds in Physiologic Conditions by F.S. de Lucena, S.H. Lewis, A.P.P. Fugolin, A.Y. Furuse, J.L. Ferracane and C.S. Pfeifer in Journal of Dental Research</p
Resistência à fratura de restaurações mod: efeito da matriz resinosa e do método de fotoativação
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Odontologia, Florianópolis, 2013O objetivo deste trabalho foi avaliar o efeito de dois compósitos, com diferentes matrizes poliméricas, e da técnica de fotoativação, sobre a resistência à fratura, por compressão, de pré-molares superiores com restaurações de classe II. Em 56 pré-molares superiores foram preparadas cavidades MOD, simulando tratamentos endodônticos, sendo os dentes divididos em quatro grupos (n=14) de acordo com os seguintes procedimentos: G1: fotoativação convencional, restauração com Filtek Z350XT (3M ESPE) e adesivo Adper Single Bond2 (3M ESPE); G2: fotoativação por pulso tardio, restauração com Filtek Z350XT (3M ESPE) e adesivo Adper Single Bond2 (3M ESPE); G3: fotoativação convencional, restauração com Filtek P90 (3M ESPE) e adesivo próprio da Filtek P90 (3M ESPE); e G4: fotoativação por pulso tardio, restauração com Filtek P90 (3M ESPE) e adesivo próprio da Filtek P90 (3M ESPE). No G1 e G3 (fotoativação convencional), a aplicação de compósito foi em incrementos de 2mm, sendo cada incremento fotoativado por 40 segundos, com aparelho do tipo LED, com intensidade de 500 mW/cm2, aferida com radiômetro (Demetron). No G2 e G4 (fotoativação por pulso tardio) a aplicação de compósito também foi com incrementos de 2mm, porém, sendo cada incremento fotoativado, inicialmente durante 5 segundos, com 300 mW/cm2. Após um período de 5 minutos foi realizada nova fotoativação, por 40 segundos, com intensidade de 500 mW/cm2. A fotoativação foi repetida para cada incremento. Após 24 horas, os espécimes foram polidos e submetidos ao teste de compressão, com ponta ativa com formato cilíndrico/arredondado (Instron-0,5mm/min). Os valores médios (newtons) após ANOVA2 e Teste de Tukey (p>0,05) foram: G1: 1157,98 (444,62); G2: 1404,14 (391,82); G3: 1255,30 (422,34); e G4: 1213,76 (419,95). A resistência à fratura, por compressão, dos pré-molares com restaurações MOD foi estatisticamente similar nos quatro grupos avaliados. Portanto, não foram verificadas diferenças significativas relacionadas aos dois compósitos, com diferentes matris poliméricas, e ao método de fotoativação, convencional e por pulsotardio. <br
Topographical aspects of airborne contamination caused by the use of dental handpieces in the operative environment
No full textBackground
The use of dental handpieces produces aerosols containing microbial agents, bacteria and viruses representing a high-risk situation for airborne cross-infections. This study aimed to map and quantify the biological contamination of a dental operatory environment using a biological tracer.
Methods
Streptococcus mutans suspension was infused into the mouth of a phantom, and an operator performed standardized dental procedures using an air turbine, a contra-angle handpiece or an ultrasonic scaler. The presence of the tracer was measured at 90 sites on the dental unit and the surrounding surfaces of the operatory environment.
Results
All tested instruments spread the tracer over the entire dental unit and the surrounding environment, including the walls and ceiling. The pattern and degree of contamination were related to the distance from the infection source. The maximum distance of tracer detection was 360 cm for air turbine, 300 cm for contra-angle and 240 cm for scaler (11.8, 9.8 and 7.9 ft, respectively). No surface of the operative environment was free from the tracer after the use of the air turbine.
Conclusions
Attention should be paid to minimize or avoid the use of rotary and ultrasonic instruments when concerns for the airborne spreading of pandemic disease agents are present.
Practical Implications.
The present study supports the recommendations of dental associations to avoid treatments generating aerosols, especially during pandemic periods. Guidelines for the management of dental procedures involving aerosols are urgently needed, as well as methods for the aerosols modification aimed to inactivate the infective agent
In vitro biofilm formation on resin-based composites cured under different surface conditions
No full textObjectives: The interfacial conditions occurring during light-curing procedures of resin-based composites (RBCs) influence their surface properties and therefore the biological behavior of the material. This study aimed to evaluate the influence of different surface curing conditions on in vitro biofilm formation by Streptococcus mutans and mixed oral microflora, in the presence or absence of surface salivary pre-conditioning. Methods: Two nanohybrid RBCs and four interfacial curing conditions (open air, argon, nitrogen and glycerin) were evaluated. Surface roughness (SR), surface elemental composition (energy-dispersive X-ray spectrometry, EDS) and biofilm formation (S. mutans and oral microcosm) were assessed. Surfaces were observed using scanning electron microscopy (SEM). Microbiological tests were performed with and without saliva pre-conditioning of the surfaces. EDS analysis was performed before and after biofilm formation, and biofilm morphology was evaluated using confocal laser scanning microscopy (CLSM). Data were analyzed using multi-way ANOVA and Tukey post-hoc test (p < 0.05). Results: Interfacial curing conditions significantly influenced SR depending on the tested RBC. EDS analysis showed that surface elemental composition was significantly influenced by the interfacial curing condition depending on the tested RBC. Interfacial curing conditions significantly influenced biofilm formation in both microbiological models in the absence of saliva pre-conditioning, depending on the tested RBC, whereas saliva pre-conditioning abrogated these effects. Conclusions: Surface curing conditions significantly impacted biofilm formation in a material-dependent manner, which was abrogated when surfaces were pre-conditioned with saliva. Clinical significance: Curing under glycerin did not improve the microbiological performances of the tested RBCs. These results, needing to be confirmed by in vivo data, have the potential to simplify operative procedures in restorative dentistry
Models of Caries Formation around Dental Composite Restorations
No full text The main reason cited for the replacement of dental composite restorations is the recurrence of caries. Numerous models—both in vitro, with acid gels or bacterial biofilms, and in situ, with dental appliances—have been used to study caries formation around dental composites. The literature shows that many factors may affect caries formation, including marginal gap formation, gap size, the local chemical environment, the durability of the bonded interface, the extent of bacterial penetration, and the presence of mechanical loading. Studies have also shown that what have been called wall lesions may form independent of surface lesions, though not likely due to microleakage through very small gap spaces in the clinical situation. Gap size and mechanical loading have been shown to be related to lesion severity within in vitro models, but these results do not correspond exactly with those obtained from in situ studies using restorations in dental appliances. Though not conclusive, some in vitro models have shown that certain materials possessing antimicrobial characteristics may reduce the severity of lesion formation, suggesting possible pathways for developing new composite and adhesive materials for restorations with potentially enhanced longevity. </jats:p
Solvent Degradation and Reduced Fracture Toughness in Aged Composites
No full text Quartz- and barium-glass-filled composites aged for more than one year in ethanol experienced a significant reduction in fracture toughness (KIc), essentially identical to that experienced after two months of aging. This reduction is mainly attributed to a softening of the resin matrix, but cracking within the resin and at the filler/ matrix interface, as revealed by SEM microscopy, may also have contributed. No significant cracking could be seen in the composites aged in water. Composites post-cured at temperatures approaching their glass-transition temperature also experienced a reduction in KIc after alcohol storage. Storage in water for one year had little effect on the KIc of composites cured at oral temperatures, but a significant increase was observed for those post-cured at elevated temperatures. This increase is difficult to explain, but appears to involve a filler/matrix interfacial phenomenon, because it was not observed in the unfilled resin. The results of this study demonstrate that an alteration in the fracture resistance and some degradation of the filler/matrix interface, as has been observed clinically, occur after long-term exposure of dental composites to certain solvents used as food-simulating liquids. </jats:p
- …
