Bonding Efficacy of a Self-adhesive Resin Cement to Enamel and Dentin

With the objective to evaluate the bonding efficacy of a new self-adhesive resin cement（RelyX Unicem, 3M ESPE） to enamel and dentin using a shear bonding strengths test with or without acid etching pretreatment, flat buccal dentin surface and mesial/distal enamel surface were made using a high-speed diamond bur. Copper rings were luted using Rely X Unicem（RU; 3M ESPE）, Panavia F（PF; Kuraray） or Vitique（VI; DMG）. For RU, the shear bonding strengths using GL（Gluma Etch, Heraeus） acid etching pretreatment were also tested. The teeth were placed into copper rings（inner diameter： 16 mm, height： 4mm） and embedded in methylmethacrylate resin. The specimens were stored for 24 h in distilled water at 37 ℃ prior to shear bonding strengths testing. In addition, bond failures were examined by optical microscope and categorized as 4 models such as different adhesive, cohesive, or mixed. Shear bonding strengths were calculated by dividing the maximum debonding force over the cross sectional area of each specimen. The Kruskal-Wallis test was used to determine pairwise statistical differences（P 〈 0.05） in SBS between the experimental groups. For dentin bonding strength, statistical analysis showed that there was no significant difference among RU（12.84 MPa）, PF（14.93 MPa） and VI（11.03 MP）; and the bonding strengths of them were higher than RU with acid etching pretreatment（9.12 MP）. When bonded to enamel, PF（17.99 MP） and VI（17.58 MP） scored significantly higher than RU efficacy.The use of self-adhesive cement Rely X Unicem can obtain the bonding strengths to dentin similar to traditional resin cements. Phosphoric acid etching can improve the bonding strengths of the selfadhesive resin cement to enamel, but was negative for dentin.

Primer containing dimethylaminododecyl methacrylate kills bacteria impregnated in human dentin blocks

Antibacterial dimethylaminododecyl methacrylate （DMADDM） was recently synthesized. The objectives of this study were to： （1） investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans impregnated into dentin blocks for the first time, and （2） compare the antibacterial efficacy of DMADDM with a previous quaternary ammonium dimethacrylate （QADM）. Scotchbond Multi-Purpose （SBMP） bonding agent was used. DMADDM and QADM were mixed into SBMP primer. Six primers were tested： SBMP control primer P, P＋2.5% DMADDM, P＋5% DMADDM, P＋7.5% DMADDM, P＋10% DMADDM, and P＋10% QADM. S. mutans were impregnated into human dentin blocks, and each primer was applied to dentin to test its ability to kill bacteria in dentinal tubules. Bacteria in dentin were collected via a sonication method, and the colony-forming units （CFU） and inhibition zones were measured. The bacterial inhibition zone of P＋10% DMADDM was 10 times that of control primer （P〈0.05）. CFU in dentin with P＋10% DMADDM was reduced by three orders of magnitude, compared with control. DMADDM had a much stronger antibacterial effect than QADM, and antibacterial efficacy increased with increasing DMADDM concentration. Dentin shear bond strengths were similar among all groups （P〉0.1）. In conclusion, antibacterial DMADDM-containing primer was validated to kill bacteria inside dentin blocks, possessing a much stronger antibacterial potency than the previous QADM. DMADDM-containing bonding agent was effective in eradicating bacteria in dentin, and its efficacy was directly proportional to DMADDM mass fraction. Therefore, DMADDM may be promisine for use in bonding agents as well as in other restorative and oreventive materials to inhibit bacteria.

Esthetic and Functional Rehabilitation of Amelogenesis Imperfecta: Report of Four Cases with a One-Year Follow-Up

In this report, we describe the performance of a conservative and minimally invasive dental approach in four patients exhibiting Amelogenesis Imperfecta (AI), a structural anomaly of the enamel. In each patient, approximately 0.5 mm of the most external, porous, and colored enamel layer was removed, and the teeth were restored using two different nanocomposites. Posterior restorations were completed with the same approach. As a result, this contemporary restorative system is a conservative and successful treatment option to restore the loss of oral esthetics and function due to AI. Rehabilitation with direct resin restorations is not only an inexpensive treatment choice, but also a more conservative technique that reduces the amount of preparation required for teeth that are already compromised.