Influência de diferentes protocolos de cimentação na resistência de união de pinos de fibra à dentina radicular / Influence of different luting protocols on the bond strength of fiber posts to root dentin

Objetivo: Avaliar a influência de diferentes protocolos de cimentação na resistência de união ao push-out de pinos de fibra cimentados adesivamente à dentina radicular bovina. Método: Os canais de 40 dentes bovinos (comprimento: 16 mm) foram preparados (profundidade: 12 mm) utilizando brocas de preparo (Nº 3, RTD). Cada canal teve sua região apical (4 mm comprimento) incluídas em resina acrílica e as raízes foram divididas em quatro grupos, de acordo com os procedimentos de cimentação(n=10): G1-sistema adesivo de frascos múltiplos com condicionamento total + pino de fibra nº 3; G2-sistema adesivo de frascos múltiplos com condicionamento total + pino de fibra nº 1; G3-sistema adesivo de frascos múltiplos com condicionamento total + pino de fibra no1 + pinos de fibra acessórios; G4-Pinos de fibra nº 3 sem condicionamento total nem procedimentos de união na dentina. Com exceção do grupo G4, a dentina radicular foi tratada com sistema adesivo de frascos múltiplos com condicionamento total (All Bond 2/Bisco). O sistema adesivo foi aplicado utilizando microbrush (Dentsply) e o excesso do material foi removido com pontas de papel absorventes. Os pinos de fibra de quartzo (Macro-Lock Illusion/RTD) foram cimentados à dentina radicular utilizando um cimento resinoso dual (Duolink/Bisco) e, em seguida, foram armazenados em água destilada previamente ao teste mecânico (24 h, 37°C). Cada espécime foi cortada em quatro fatias (1,8 mm de espessura), as quais foram submetidas ao ensaio de push-out em máquina de ensaio universal (1mm/min). Os dados (MPa) foram analisados estatisticamente pela análise de variância (ANOVA-1 fator)...

Resultados: Os valores médios (±DP) obtidos após o ensaio de push-outforam: G1- 5,4±1,3 MPa; G2- 4,2±2,4 MPa; G3-4,6±1,5 MPa; G4-3,3±1,7 MPa. Anova demonstrou não haver significância estatística entre os grupos (p=0,0966). A hipótese foi rejeitada. Conclusão: A resistência de união de pinos de fibra à dentina radicular não foi influenciada pelos protocolos de cimentação avaliados...

Objective: To evaluate the influence of different luting protocols on the push-out bond strength of fiber posts cemented to bovine root dentin. Method: Forty bovine root canals (length: 16 mm) were prepared up to 12 mm using #3 (RTD) preparation burs. Each canal had its apical 4 mm embedded in acrylic resin and the roots were assigned to four groups (n=10), according to the cementation procedures: G1: etch-and-rinse multi-bottle adhesive system + #3 fiber post; G2: etch-and-rinse multibottle adhesive system + #1 fiber post; G3: etch-and-rinse multi-bottle adhesive system + #1 fiber post + accessory fiber posts; G4: #3 fiber post without etching and bonding procedures to dentin. Except for G4, root dentin was treated with the etch-and-rinse multi-bottle adhesive system All Bond 2 (Bisco). The adhesive system was applied with a microbrush (Dentsply) and excess material was removed withabsorbent paper points. The quartz fiber posts (Macro-Lock Illusion/RTD) were cemented to the root dentin with a dual-cure resin cement (Duolink/Bisco) and were stored in distilled water (for 24 h at 37 °C) before the mechanical tests. Each sample was cut into four slices (1.8 mm thick) that were subjected to push-out tests in a universaltesting machine (1 mm/min). The data (in MPa) were analyzed statistically by one-way ANOVA. Results: The mean push-out bond strength values (±SD) were: G1: 5.4 ± 1.3 MPa; G2: 4.2 ± 2.4 MPa; G3: 4.6 ± 1.5 MPa and G4: 3.3 ± 1.7 MPa. One-way ANOVA showed no statistically significant differences among the groups. The tested hypothesis was discarded. Conclusion: The push-out bond strength of fiber posts to root dentin was not influenced by the evaluated luting protocols...

Effects of cement-curing mode and light-curing unit on the bond durability of ceramic cemented to dentin

The aim of this study was to evaluate the effects of different light-curing units and resin cement curing types on the bond durability of a feldspathic ceramic bonded to dentin. The crowns of 40 human molars were sectioned, exposing the dentin. Forty ceramic blocks of VITA VM7 were produced according to the manufacturer's recommendations. The ceramic surface was etched with 10% hydrofluoric acid / 60s and silanized. The dentin was treated with 37% phosphoric acid / 15s, and the adhesive was applied. The ceramic blocks were divided and cemented to dentin according to resin cement / RC curing type (dual- and photo-cured), light-curing unit (halogen light / QTH and LED), and storage conditions (dry and storage / 150 days + 12,000 cycles / thermocycling). All blocks were stored in distilled water (37°C / 24h) and sectioned (n = 10): G1 - QTH + RC Photo, G2 - QTH + RC Dual, G3 - LED + RC Photo, G4 - LED + RC Dual. Groups G5, G6, G7, and G8 were obtained exactly as G1 through G4, respectively, and then stored and thermocycled. Microtensile bond strength tests were performed (EMIC), and data were statistically analyzed by ANOVA and Tukey's test (5%). The bond strength values (MPa) were: G1 - 12.95 (6.40)ab; G2 - 12.02 (4.59)ab; G3 - 13.09 (5.62)ab; G4 - 15.96 (6.32)a; G5 - 6.22 (5.90)c; G6 - 9.48 (5.99)bc; G7 - 12.78 (11.30)ab; and G8 - 8.34 (5.98)bc. The same superscript letters indicate no significant differences. Different light-curing units affected the bond strength between ceramic cemented to dentin when the photo-cured cement was used, and only after aging (LED > QTH). There was no difference between the effects of dual- and photo-cured resin-luting agents on the microtensile bond strength of the cement used in this study.

Trauma oclusal x tecidos periodontais: ação da osteopontina e do receptor ativador do fator nuclear kappa B / Occlusal trauma x periodontal tissue: action of the osteopontin and receptor activator of nuclear factor Kappa B ligand

O trauma oclusal é causado pela força oclusal excessiva e muitas vezes está associado com a perda do osso alveolar. Na presença de trauma oclusal, periodontites provocadas por biofilme estão sujeitas a ter uma evolução mais rápida que periodontites onde o trauma oclusal não está associado. Nesta revisão foi detalhada a atuação de duas proteínas (osteopontina e RANKL) que podem estar envolvidas neste processo. Sabe-se que a osteopontina é uma proteína produzida sob carga mecânica e induz a migração dos osteoclastos para o local da reabsorção. O receptor ativador do fator nuclear Kappa B (RANKL) é um importante fator na diferenciação, ativação e sobrevivência dos osteoclastos, e participa da indução in vitro da osteopontina intracelular. Entretanto, o envolvimento do RANKL na reabsorção óssea inflamatória, com ou sem trauma oclusal, e o papel da osteopontina nas células ainda não está claro. No presente estudo, uma revisão de literatura foi realizada com o objetivo de elucidar a imunohistoquímica do trauma oclusal associado aos tecidos periodontais, enfatizando a atuação da osteopontina e do RANKL, assim como a relação entre o trauma oclusal e os tecidos periodontais. Com base no que existe atualmente na literatura, o mecanismo preciso de degradação periodontal sob excessiva carga oclusal ainda não está bem estabelecido em virtude da complexa ação das referidas proteínas.

The occlusal trauma is caused by excessive occlusal loading and many times are associated with the anatomy ofthe osseous structures. In the presence of occlusal loading, periodontitis caused for bacterial film could be an evolution faster than periodontitis disease where the occlusal trauma is not associated. In this review, it will be emphasized the action of two proteins (osteopontin and RANKL) that can be involved in this process. The osteopontin is known to be reduced upon mechanical loading and is considered to induce migration of osteoclasts to the resorption bone. The receptor activator of nuclear factor Kappa B (RANKL) is an important factor in the differentiation, activation and survival of the osteoclasts, and participates of the induction in vitro of the intracellular osteopontin. However, the evolvement of the RANKL in the inflammatory osseous resorption, with or without oclusal loading, and the function of the osteopontin in the cells is unclear. In the present study, a literature review was carried through with the objective to elucidate the immunohistochemistry of the occlusal trauma associate to the periodontal tissues, emphasizing the action of osteopontin and RANKL, as well as the relation between the occlusal loading and periodontal tissues. On the basis of what it exists currently in literature, the necessary mechanism of the fabric periodontal under excessive occlusal loading was unclear because of the complex action of these proteins.

Pulpal temperature increase with high-speed handpiece, Er-YAG laser and ultrasound tips

The aim of this study was to compare intrapulpal temperature increase produced by high-speed handpiece, Er:YAG laser and CVDentus ultrasound tips during cavity preparation. Thirty bovine mandibular incisors with an enamel/dentin thickness of 4 mm at buccal surface had their roots amputated and were allocated to the following groups (n=10): Group I- high-speed handpiece; Group II- noncontact Er:YAG laser (250 mJ/4Hz); and Group III- CVDentus ultrasouns tips. All devices were used with water cooling. Class V cavities were prepared to a depth of 3.5 mm, measured with a periodontal probe. A type T thermocouple was placed inside the pulp chamber to determine the temperature increase (°C), which was recorded by a data acquisition system ADS 2000 IP (Lynx Technology) linked to a notebook computer. Data were analyzed statistically by oneway ANOVA and Tukey’s test (p=0.05). The mean temperature rises were: 1.10°C (±0.56) for Group I, 0.84°C (±0.55) for Group II, and 3.00°C (± 1.34) for Group III. There were no statistically significant differences (p>0.05) between Groups I and II, but both of them differed significantly from Group III (p<0.05). In conclusion, the use of Er:YAG laser and high-speed handpiece for cavity preparation resulted in similar temperature increase. Although ultrasound tips generated significantly higher intrapulpal temperature increase, it remained below the critical value of 5.5°C and may be considered safe for use.