No abstract

Enamel demineralization is a common problem found in patients using orthodontic devices, such as orthodontic braces. It was found that Streptoccocus mutans growth increases adjacent to orthodontic devices, which may result in caries development. Incorporated antibacterial quaternary ammonium polyethylenimine (QPEI) nanoparticles were previously shown to be highly efficacious against various bacteria. Combining antibacterial materials in orthodontic cement may be advantageous to prevent bacterial outgrowth adjacent to orthodontic brackets. The aim was to evaluate the efficiency of orthodontic cement containing QPEI nanoparticles in reducing S. mutans and Lactobacillus casei outgrowth adjacent to orthodontic brackets. Orthodontic brackets were bonded to the buccal surfaces of extracted lower incisors. The antibacterial effect on S. mutans and L. casei outgrowth of Neobond bracket adhesive orthodontic cement with and without QPEI nanoparticles was compared. The antibacterial effect was evaluated using crystal violet staining and bacterial count (CFU/mL). The teeth in the experimental group, with the QPEI nanoparticles cement, showed significantly lower optical density (OD) values and CFU counts of S. mutans and L. casei than the teeth in the control group (p < 0.05). Based on the results, it can be concluded that orthodontic cement containing QPEI nanoparticles significantly inhibits S. mutans and L. casei growth around orthodontic brackets.

A clear trend in favor of composite resin restorations is evident in the 13-year survey and suggests a move toward an amalgam-free era.

Objectives:The dental field is gradually reducing the use of amalgam and moving towards adhesive restoration. This change is in accordance with the advancement and improvement of composite resin materials and adhesion systems. Consequently, posterior cavity preparations teaching should be re-examined to determine whether dental schools are adapting their curriculum to fit the current trends in dentistry and what rationale supports their decisions.Methods: An online questionnaire was constructed to assess the time dedicated to teaching composite materials and amalgam, in addition to the principles of posterior preparations, for composite restorations in North American dental schools. Results:A total 33 schools responded to the questionnaire. A large variation was found in teaching methods and techniques of posterior restorations. The reasoning for teaching amalgam restorations was diverse as were the principles of composite resin preparation taught. Conclusion:No agreed principles of cavity preparation for resin composite restorations were found, as opposed to explicit agreement on amalgam cavity preparations.The results demonstrate a lack of clear guidelines for cavity preparation of resin composite restorations. Dental schools may benefit when a consensus on this topic is achieved. K E Y W O R D Scomposite restoration, dental education, dental material 356 | ZABROVSKY et Al.(a) Access to the carious lesion only from the buccal or lingual aspects, whilst preserving the marginal ridge area, 15,16 (b) A "minibox" or "box-only" type of preparation that includes only a box, with removal of the marginal ridge area. The studies did not show an increased failure rate for this approach compared with standard class II in 2-and 5-year follow-up. 16 An additional classification, different from GV Black's traditional principles, was developed. This classification, compatible with the minimally invasive approach, divides cavities into four types (sizes 1-4) and is based on the progression of the carious lesion and the involvement of enamel and dentin. 17The continuing shift in restoration materials requires dental schools to adapt to the changing reality. 6,9 To understand the present trend in the shift from amalgam to composite materials and the reaction of the dental schools, we decided to review the teaching of this topic in North American dental schools. | MATERIAL S AND ME THODSAn online questionnaire was constructed including 11 multiplechoice questions and five open-ended questions-all requiring a numeric answer (Appendix 1). The questionnaire was directed so as to assess the time dedicated to teaching composite materials and amalgam, in addition to the principles of posterior preparations for composite restorations. It was designed by the head of restorative dentistry course in cooperation with other pre-clinical teachers.

Some clear trends are apparent in the current survey: the use of two implants, no use of bar connectors and delayed loading of the implants. It is likely that graduates will not have sufficient clinical skills and will need continuing education to be familiar with the required procedures, both surgical and prosthetic.