Immediate dentin sealing influences the fracture strength of ultrathin occlusal veneers made of a polymer-infiltrated ceramic network.

OBJECTIVE: The objective of this laboratory study was to assess the effect of immediate dentin sealing (IDS) on the fracture strength of teeth restored with ultrathin occlusal veneers made of a polymer-infiltrated ceramic network (PICN - Vita Enamic) with different fissure/cusp thicknesses. METHODS: Forty third molars were identically prepared in the dentin and allocated into four groups (n = 10) according to the fissure/cusp thickness of the occlusal veneers (0.3/0.6 mm or 0.6/0.9 mm) and the application or not of the IDS technique. Ten sound third molars were used as the control group. IDS was performed using a universal adhesive system (Single Bond Universal). The prepared teeth were scanned (Cerec software, version 4.1), and the occlusal veneers were shaped following the occlusal anatomy of a right second molar. Blocks of PICN were milled in the unit inLab MC XL. Following luting with Single Bond Universal and RelyX Ultimate, the fracture strength of the specimens was obtained with a universal testing machine. The fractures were classified as reparable or irreparable. Fracture strength values were analyzed with 2-way and 1-way ANOVA (α = 0.05) and Tukey's test. RESULTS: Only the IDS factor was significant (p = 0.001). The teeth restored with IDS (2875 ± 508 N) achieved significantly higher fracture strength than the teeth restored without IDS (2263 ± 354 N) (p < 0.05). The fracture strength of the specimens with IDS did not differ significantly from that of the sound teeth (3230 ± 620 N). The fractures were predominantly reparable. CONCLUSION: IDS improved the fracture strength of ultrathin occlusal veneers made of PICN.

Examining the effects of acid etching duration on the bond strength between two CAD/CAM materials and one composite resin.

This study aimed to evaluate the effect of three hydrofluoric acid (HF) etching periods on the micro-tensile bond strength between two CAD-CAM ceramic systems [Vita Suprinity (VS) and feldspathic CEREC blocs (CB)] and a composite resin. The ceramics were categorized into six groups based on the surface conditioning protocol used, as follows: G1: CB-HF 5% for 20 s; G2: CB-HF 5% for 40 s; G3: CB-HF 5% for 60 s; G4: VS-HF 5% for 20 s; G5: VS-HF 5% for 40 s; G6: VS-HF 5% for 60 s. Scotchbond Universal was applied onto the pretreated ceramic surfaces and covered with Filtek Z350 XT composite resin. After 24 h, the specimens were cut into microbars (n = 16) and a micro-tensile bond strength test (µTBS) was carried out. An optical microscope was used to examine the fractured microbars. The results showed statistically significant differences between the factors tested (p < 0.01). Moreover, the mean MPa of G1(17.27), G2(13.03), G3(12.82), G4(15.83), G5(21.66), and G6(14.50) was seen to significantly differ. The predominant failure type observed was adhesive, and all three periods of HF etching produced satisfactory bonding between the composite resin and CB. An etching time of 40 s provided the highest µTBS value for VS.

Microtensile bond strength of CAD/CAM materials to dentin under different adhesive strategies.

The present study aimed to evaluate the microtensile bond strength (µTBS) of novel computer-aided design/computer-aided manufacturing (CAD/CAM) restorative materials to dentin using different adhesive strategies. Thirty-two crowns were milled using CAD/CAM materials (Vita Mark II as control, Vita Suprinity, Vita Enamic and Lava Ultimate) and luted to dentin using different resin cements (RelyX ARC, RelyX Unicem 2 and RelyX Ultimate). The specimens were stored in 100% relative humidity at 37°C for 24 h and sectioned. The samples (n = 16) with cross-sectional areas of approximately 0.90 mm2, were submitted to a µTBS test in a universal testing machine with a crosshead speed of 0.5 mm/min. The samples were analyzed with SEM to determinate the failure mode. According to 2-way ANOVA and Tukey's test (α=0.05), the interaction effect (material x luting strategy) was significant (p=0.001). Regardless of the luting strategy, a higher µTBS was obtained with Lava Ultimate and Vita Enamic, which were significantly different from Vita Mark II and Vita Suprinity (p<0.05). For Vita Mark II, Vita Suprinity, Vita Enamic, and Lava Ultimate, the µTBS obtained with RelyX Unicem 2 was not significantly different from that obtained with RelyX ARC or RelyX Ultimate. All groups obtained at least three types of failure. The adhesive strategy with self-adhesive resin cement was comparable to conventional resin cement with total-etch or self-etch adhesive techniques in the bond of novel CAD/CAM materials to dentin.

Microtensile bond strength of CAD/CAM materials to dentin under different adhesive strategies

Abstract: The present study aimed to evaluate the microtensile bond strength (μTBS) of novel computer-aided design/computer-aided manufacturing (CAD/CAM) restorative materials to dentin using different adhesive strategies. Thirty-two crowns were milled using CAD/CAM materials (Vita Mark II as control, Vita Suprinity, Vita Enamic and Lava Ultimate) and luted to dentin using different resin cements (RelyX ARC, RelyX Unicem 2 and RelyX Ultimate). The specimens were stored in 100% relative humidity at 37°C for 24 h and sectioned. The samples (n = 16) with cross-sectional areas of approximately 0.90 mm2, were submitted to a μTBS test in a universal testing machine with a crosshead speed of 0.5 mm/min. The samples were analyzed with SEM to determinate the failure mode. According to 2-way ANOVA and Tukey's test (α=0.05), the interaction effect (material x luting strategy) was significant (p=0.001). Regardless of the luting strategy, a higher μTBS was obtained with Lava Ultimate and Vita Enamic, which were significantly different from Vita Mark II and Vita Suprinity (p<0.05). For Vita Mark II, Vita Suprinity, Vita Enamic, and Lava Ultimate, the μTBS obtained with RelyX Unicem 2 was not significantly different from that obtained with RelyX ARC or RelyX Ultimate. All groups obtained at least three types of failure. The adhesive strategy with self-adhesive resin cement was comparable to conventional resin cement with total-etch or self-etch adhesive techniques in the bond of novel CAD/CAM materials to dentin.

Clinical-surgical treatment of temporomandibular joint disorder in a psoriatic arthritis patient.

INTRODUCTION: Condylotomy is a surgical procedure that has been used as an option to treat temporomandibular disorder (TMD) patients. This technique has the advantage of avoiding intra-capsular alterations that might be found involving other surgical procedures. Its use, even when unilateral, has positive effect on treatment of both joints. METHODS: In order to better evaluate the benefits of a clinical-surgical treatment for TMD, the present report describes the case of a psoriatic arthritis patient. The case was clinically characterized by dental malloclusion, and imaging exams showed joint degeneration of the right mandibular condyle. The patient was treated by condylotomy technique after a prosthetic oral rehabilitation. RESULTS: No clinical-radiological signs or symptoms of progression of articular disease were observed within a period of 16 months after surgery. Furthermore, there was functional stability of the temporomandibular joint, total absence of local pain and improvement of mouth opening. CONCLUSION: The present study suggests that condylotomy can be considered as a valid option for the management of TMD, since it has low surgical morbidity and favorable clinical outcomes. In this case, the patient had a medical diagnosis of systemic disease presenting general pain and pain at the temporomandibular joint (TMJ), in addition of causal agent of TMD (dental malloclusion). The difficulty of finding a single etiology (malocclusion vs. systemic disease) did not exclude the indication of a clinical-surgical treatment to re-establish the balance of TMJ.

Argon and Nd:YAG lasers for caries prevention in enamel.

OBJECTIVE: The aim of this study was to investigate the effect of Nd:YAG and argon laser irradiations on enamel demineralization after two different models to induce artificial caries. BACKGROUND DATA: It is believed that the use of the high-intensity laser on the dental structure can lead to a more acid-resistant surface. MATERIALS AND METHODS: Twenty-one extracted human third molars were sectioned into tooth quarters. The quarters were distributed in three groups: Group I (control), untreated; Group II, Nd:YAG laser (60 mJ, 15 pps, 47.77 J/cm(2), 30 sec); and Group III, argon laser (250 mW, 12 J/cm(2), 48 sec). Tooth quarters from each group were subjected to two different demineralization models: cycle 1, a 14 day demineralization (pH 4.5; 6 h) and remineralization (pH 7.0; 18 h) solutions, 37 °C and cycle 2, 48 h in demineralization solution (pH 4.5). Samples were prepared in slices (60-100 µm thick) to be evaluated under polarized light microscopy. Demineralization areas were measured (mm(2)) (n=11). Data were analyzed by ANOVA and Tukey's test (p<0.05). RESULTS: Means followed by different letters are significantly different: 0.25 A (control, cycle 48 h); 0.18 AB (control, cycle 14 days); 0.17 AB (Nd:YAG, cycle 14 days); 0.14 BC (argon, cycle 48 h); 0.09 BC (Nd:YAG, cycle 48 h), and 0.06 C (argon, cycle 14 days). CONCLUSIONS: The argon laser was more effective for caries preventive treatment than Nd:YAG laser, showing a smaller demineralization area in enamel.

Resistência à microtração de três sistemas adesivos à dentina / The microtensile bond strength of three adhesive systems to dentin

O objetivo deste trabalho foi avaliar, in vitro, a resistência de união à microtração sobre a dentina dos sistemas adesivos Single Bond (3M), Optibond Solo Plus (Kerr) e Clearfil SE Bond (Kuraray) e classificar o tipo de fratura após a falha. Foram utilizados seis terceiros molares humanos, que foram divididos em três grupos. A remoção da superfície oclusal foi realizada com um disco diamantado de dupla face em baixa rotação, com água, seguida da utilização de lixas de carbeto de silício de granulações #320 e #600, de maneira a expor uma superfície plana de dentina, onde foram aplicados os sistemas adesivos, seguidos da aplicação da resina composta Z250/3M. Os dentes foram armazenados em água destilada por 24 horas a 37°C. Então, estes foram seccionados paralelamente ao longo eixo do dente, secções de 0,6 ± 0,2 mm², nos sentidos vestíbulo-lingual e mésio-distal e 20 corpos-de-água foram selecionados para cada sistema adesivo. O teste de resistência à microtação foi realizado com uma velocidade de 0,5 mm/min. As médias dos resultados foram: 33,26 ± 8,3MPa para o Single Bond, 33,54 ± 9,9MPa para o Optibond Solo Plus e 45,56 ± 12,2 MPa para o Clear SE Bond. O tipo de falha predominante no estudo foi a adesiva (76,66 por cento). Foi possível concluir que o Clearfil SE Bond apresentou a maior resistência de união à microtração, sendo diferente estatisticamente dos demais sistemas adesivos testados, que obtiveram valores semelhantes entre si