Influence of mixing disinfectant solutions into alginate on working time and accuracy

Possible transfer of pathogens from dental surgery to dental laboratory is of concern to the profession. This study investigates changes in the working time and accuracy of an alginate impression material when mixed with solutions of selected disinfectants rather than water. The results indicate that certain disinfectant solutions, when used as a water substitute, do not modify the working time of the alginate investigated beyond acceptable limits and have no significant effect on the dimensional accuracy of that material. The use of a 0.2 per cent solution of chlorhexidene gluconate is recommended as a water substitute for the alginate investigated.     

放射线检查在龋病诊断中的价值

放射线检查是龋病诊断中常用的辅助手段，本文讨论了根尖片与翼片、数字式根尖片与数字式翼片、放射屏幕影像仪（ＲＶＧ）、纵向显微放射法（ＬＭＲ）、激光诱导荧光法（ＬＡＦ）等方法在龋病诊断中的优缺点。并提出以直接数字式系统取代湿片过程和胶片贮存，尽量减少射线剂量、以及将龋病的诊断定位于早期脱矿阶段是放射线检查在龋病诊断中的发展方向。     

Apical extrusion of intracanal bacteria following use of various instrumentation techniques

Aim To evaluate the number of bacteria extruded apically from extracted teeth ex vivo after canal instrumentation using a manual technique and three engine‐driven techniques utilizing nickel–titanium instruments (K3, RaCe, and FlexMaster). Methodology Seventy extracted human mandibular premolar teeth with similar dimensions were used. Access cavities were prepared and root canals were then contaminated with a suspension of Enterococcus faecalis and then dried. The contaminated roots were divided into four experimental groups of 15 teeth each and one control group of 10 teeth. G1. RaCe group: the root canals were instrumented using RaCe instruments. G2. K3 group: the root canals were instrumented using K3 instruments. G3. FlexMaster group: the root canals were instrumented using FlexMaster instruments. G4. Manual technique group: the root canals were instrumented using K‐type stainless steel instruments. G5. Control group: no instrumentation was attempted. Bacteria extruded from the apical foramen during instrumentation were collected into vials. The resultant microbiological samples were removed from the vials and then incubated in culture media for 24 h. The number of colony‐forming units (CFU) was determined for each sample. The data obtained were analysed using the Kruskal–Wallis one‐way analysis of variance and Mann–Whitney U‐tests, with α = 0.05 as the level for statistical significance. Results There was a significant difference between experimental‐control and engine‐driven‐manual technique groups (P < 0.05). The manual technique was associated with the greatest extrusion of microorganism. Conclusions All instrumentation techniques extruded intracanal bacteria apically. No significant difference was found in the number of CFU among the engine‐driven techniques; manual techniques extruded significantly more microorganisms.     

An in vitro investigation of peak insertion torque values of six commercially available mini-implants

This study compared peak insertion torque values of six commercially available self-drilling mini-implants [Mini Spider? screw (1.5 × 8 mm), Infinitas? (1.5 × 9 mm), Vector TAS? (1.4 × 8 mm), Dual Top? (1.6 × 8 mm), Tomas Pin? (1.6 × 8 mm), and Ortho-Easy? (1.7 × 6, 8, and 10 mm)]. Twenty implants each were drilled into acrylic rods at a speed of 8 rpm using a motorized torque measurement stand, and the values were recorded in Newton centimetres (Ncm). A further 20 Ortho-Easy? implants with a length of 6 and 10 mm were tested at 8 rpm; 20 implants of 6 mm length were also tested at 4 rpm. Kaplan-Meier estimates of the peak torque values were compared using the log-rank test with multiple comparisons evaluated by Sidak's test. There were significant differences in the maximum torque values for different mini-implants with the same length. The Mini Spider? screw and Infinitas? showed the lowest average torque values (6.5 and 12.4 Ncm) compared with Vector TAS?, Dual ToP?, Tomas Pin?, and Ortho-Easy? (30.9, 29.4, 25.4, and 24.8 Ncm, respectively). There was no correlation between the diameter of the implants and torque values. The Tomas Pin? showed the largest standard deviation (7.7 Ncm) and the Dual Top? implant the smallest (0.6 Ncm). Different insertion speeds did not result in significant differences in peak torque values but the 6 mm mini-implants showed significantly higher torque values than the 8 and 10 mm implants. Using a 'torque limiting' screwdriver or pre-drilling cortical bone to reduce insertion, torque appears justified for some of the tested implants.     

Predoctoral implant dentistry curriculum survey: European dental schools

PURPOSE: In 2002 a survey of European dental schools was conducted. The purpose of the survey was to determine the curricular structure, teaching philosophies and materials used in predoctoral implant dentistry courses. MATERIALS AND METHODS: Fifty-six European dental schools were randomly selected from the Association for Dental Education in Europe representing 33 countries. A questionnaire was mailed to the predoctoral implant dentistry director/chairperson of the selected European dental schools. Of these, 40 schools returned the completed survey, resulting in a response rate of 71%. The mean, median and range of responses were computed where applicable. RESULTS: The results from this survey show that 80% of the responding schools required a course in implant dentistry. Between 1997 and 1999 over a third of responding schools (36%) incorporated a predoctoral implant dentistry course into their curriculum. Eighty-seven per cent of the schools have some prosthodontists teaching the course. Thirty-seven per cent of schools are offering a laboratory course in conjunction with the implant course. Sixty-three per cent of the schools are not restoring implant cases at the predoctoral level. However, 68% of schools reported students are required to be present during implant surgery. Ten per cent of schools require that the implant-related laboratory work be completed by the students. CONCLUSIONS: Predoctoral implant dentistry educational programmes vary from school to school. Yet a large percentage of schools agree on certain topics, including the importance of including implant education in predoctoral dental programmes.