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OBJECTIVES: To evaluate the effect of the application of an additional hydrophobic bonding resin on the clinical performance of a universal adhesive applied in etch-and-rinse (ER) or self-etch adhesive (SE) strategy in non-carious cervical lesions (NCCLs) after 5 years. MATERIALS AND METHODS: Scotchbond Universal Adhesive (3M Oral Care) was applied in 134 NCCLs of 39 subjects using different adhesion approaches: 3-step ER (3-ER), 2-step ER (2-ER), 2-step SE (2-SE), and 1-step SE (1-SE). Enamel and dentin were acid etched prior to application of the universal adhesive for the 3-ER and 2-ER groups. An extra layer of a hydrophobic bonding resin was applied for groups 3-ER and 2-SE. All lesions were restored with Filtek Supreme XTE resin composite (3M Oral Care). Restorations were evaluated at baseline and at 5 years using the modified USPHS criteria. Mann-Whitney U and Wilcoxon tests were performed, and the survival rates (retention/fracture) were analyzed using Kaplan-Meier and log-rank tests (p < 0.05). RESULTS: The recall rate was 66.7% at 5 years. The cumulative survival rate was 96.9% for 3-ER, 96.8% for 2-ER, 71.4% for 2-SE, and 81.3% for 1-SE strategies. The log-rank test was statistically significant (p = 0.006). Retention rates were 100% for both ER groups, 75% for 2-SE and 81.3% for 1-SE. At 5 years, 2- and 1-SE approaches showed similar retention rates, but lower than those for 3- and 2-ER. A significant decrease in retention rate was detected for 2-SE (p = 0.007) and 1-SE (p = 0.014) groups between baseline and 5 years. All groups, except 2-ER, showed an increase in marginal discoloration. For this parameter, significant differences were detected between 2-ER and 1-SE (p = 0.004). CONCLUSIONS: The addition of a hydrophobic bonding resin to the recommended application sequence of Scotchbond Universal Adhesive did not improve its clinical performance in NCCLs after 5 years. Higher retention rates were measured when this adhesive was applied in ER mode. TRIAL REGISTRATION: This manuscript is a 5-year follow-up of a randomized clinical trial that started in 2012 when there was no strong recommendation for registration in clinicaltrials.gov. The results after 36 months of clinical service were previously published in this journal.

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Dental caries is the major biofilm-mediated oral disease in the world. The main treatment to restore caries lesions consists of the use of adhesive resin composites due to their good properties. However, the progressive degradation of the adhesive in the medium term makes possible the proliferation of cariogenic bacteria allowing secondary caries to emerge. In this study, a dental adhesive incorporating a drug delivery system based on L-arginine-containing mesoporous silica nanoparticles (MSNs) was used to release this essential amino acid as a source of basicity to neutralize the harmful acidic conditions that mediate the development of dental secondary caries. The in vitro and bacterial culture experiments proved that L-arginine was released in a sustained way from MSNs and diffused out from the dental adhesive, effectively contributing to the reduction of the bacterial strains Streptococcus mutans and Lactobacillus casei. Furthermore, the mechanical and bonding properties of the dental adhesive did not change significantly after the incorporation of L-arginine-containing MSNs. These results are yielding glimmers of promise for the cost-effective prevention of secondary caries.

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BACKGROUND: The first state of alarm due to COVID-19 in Spain led to limit dental treatment exclusively to emergencies. The objective of the survey was to evaluate the amount and type of emergencies attended during this period, as well as to know how they were solved, and what measures were adopted to carry out dental care in these exceptional circumstances. MATERIAL AND METHODS: This cross-sectional study included 312 Spanish dentists, who fulfilled an online questionnaire with 22 closed questions, divided into five sections regarding to various aspects of professional dental profile and emergency care. Descriptive statistic and Chi-square tests were performed (p<0.05). RESULTS: 75.64% of respondents attended emergencies in person only when required, being dental pain the main emergency (90.38%). Dental emergency care in person involved a prior telephone triage of the patient to identify possible COVID-19 symptoms, as well as protective measures implementation for both, the patient and the dentist, at dental office. CONCLUSIONS: The number of dental emergencies decreased during the state of alarm, being dental pain the main cause of dental assistance via telephone or in person. Triage of patients before scheduling an in-person appointment and protective measures implementation were common features in dental emergency care during the first state of alarm period. Key words:Dental emergencies, COVID-19, state of alarm, survey.

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OBJECTIVES: To evaluate if the addition of a layer of a hydrophobic bonding resin to the recommended application sequence of a universal adhesive improves the respective clinical behavior in non-carious cervical lesions (NCCLs) after 36 months. MATERIALS AND METHODS: Scotchbond Universal Adhesive (SBU, 3M Oral Care) was applied in NCCLs of 39 subjects using four adhesion strategies: (1) three-step ER (etch-and-rinse), (2) two-step ER, (3) two-step SE (self-etch), and (4) one-step SE. An extra layer of a hydrophobic bonding resin was applied for strategies three-step ER and two-step SE. The same composite resin (Filtek Supreme XTE, 3M Oral Care) was used for all strategies. Restorations were evaluated at baseline and 18 and 36 months using the modified United States Public Health Service (USPHS) criteria. Kruskal-Wallis, Mann-Whitney U, Friedman, and Wilcoxon non-parametric tests were computed. RESULTS: The cumulative failure rate was 8.6%. The 36-month retention rates were 100% for both 3-ER and 2-ER, 76.0% for 2-SE, and 86.2% for 1-SE. A lower retention rate was observed for two-step SE at 36 months compared with both three-ER (p < 0.01) and two-ER (p < 0.01). Identical retention rates were measured for the two SE groups. When retention rate was compared at baseline versus 36 months for each adhesion strategy, a significant decrease was observed for 2-SE. The restorations performed with 3-ER, 2-SE, and 1-SE had a significant deterioration in marginal discoloration at the 18-month recall. CONCLUSIONS: The 36-month clinical performance of Scotchbond Universal Adhesive improved for both etch-and-rinse strategies. CLINICAL RELEVANCE: Phosphoric acid etching is still recommended to provide retention to composite restorations in NCCLs.

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OBJECTIVES: There are many works that have attempted to estimate the fracture toughness of enamel by indentation techniques using equations whose success in determining the actual value of fracture toughness, rely on a particular three-dimensional pattern consisting of cracks growing from the edges of the indentation. Recently, an alternative methodology based on an energetic approach has been developed to estimate the fracture toughness of coatings by depth sensing indentation that is not less affected by the cracks pattern generated. In this work, the energetic approach to indentation fracture toughness of bovine enamel is presented and compared with those toughness values obtained using the traditional expressions reported in the literature. METHODS: Indentation tests were carried out using a diamond Berkovich indenter onto the enamel surface of eight incisors from bovines of two years old. A continuous stiffness measurement methodology was used with a frequency of 45 Hz and displacement amplitude of 2 nm up to a maximum penetration depth of 2000 nm. RESULTS: The results showed that some modifications in the energetic methodology should be performed in order to apply it successfully. SIGNIFICANCE: The fracture toughness values obtained using the traditional equation and applying the energetic methodology, were significantly different, although the values were within the range obtained by other authors.

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PURPOSE: To determine the influence of curing mode on the surface hardness of seven resin cements used to lute indirect composite restorations. MATERIALS AND METHODS: Seven commercial dual-curing resin cements were tested: two were total-etch (RelyX ARC [3M ESPE, St. Paul, MN, USA] and Variolink II [Ivoclar Vivadent, Schaan, Liechtenstein]); one was self-etch (Multilink Automix [Ivoclar Vivadent]), and four were self-adhesive (RelyX Unicem [3M ESPE], Maxcem Elite [Kerr Corp., Orange, CA, USA], SmartCem2 [Dentsply, Detrey, GmbH, Konstanz, Germany], and G-Cem [GC CORPORATION, Itabashi-Ku, Tokyo, Japan]). Three specimens (0.5 × 6.5mm) of each material were prepared for each of three experimental groups: Group 1 (cements allowed to self cure); Group 2 (cements light-cured for 40 seconds); and Group 3 (cements light-cured for 80 seconds). All specimens were cured through a 4-mm-thick composite cylinder (Filtek Z250-A3). Surface microhardness numbers were determined at 20 min after preparation. Results were analyzed by two-way analysis of variance and Student-Newman-Keuls tests (p<0.05). RESULTS: Superficial hardness was significantly influenced by the resin cement tested (p<0.0001), the curing mode (p<0.0001), and their interaction (p<0.0001). RelyX ARC exhibited the highest mean microhardness values regardless of the curing mode. Light-curing significantly increased the microhardness of all resin cements studied, and these values increased even further with a doubling of irradiation time. Self-adhesive cements exhibited different behavior according to the curing mode. RelyX Unicem was highly sensitive to light irradiation, showing the lowest mean values in the self-curing mode. After light irradiation for 40 or 80 seconds, Maxcem Elite exhibited the lowest mean hardness values of all the resin cements tested. CONCLUSION: The microhardness of resin cements is highly dependent on the brand. Dual-curing resin cements should always be light irradiated for longer periods than that recommended by manufacturers. CLINICAL SIGNIFICANCE: Dual-curing resin cements should always be light-cured for longer irradiation times, as light irradiation for 80 seconds yields the highest microhardness values in comparison with self-curing or light irradiation for 40 seconds. However, some self-adhesive resin cements exhibit low microhardness values when used to cement 4-mm-thick indirect composite restorations regardless of the curing mode applied.

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