Locator retention: does variation in number and configuration matter?

This pilot study was designed to collect initial data on overdenture attachment retention in varying configurations of attachment location in an implant-retained mandibular overdenture. A clear acrylic model of a mandible with 6 numbered implants and Locator resilient abutments was used to simulate implant placement in a patient. A clear acrylic denture was fabricated with 6 Locator housings to match the implants in the model. Attachments were tested in 4 different configurations: 2 implants, 2 and 5 (T25); 4 implants, 2-5 (T2345); 4 implants, 1, 3, 4, and 6 (T1346); and 6 implants, 1-6 (T1-6). Clear nylon male inserts were used for each test. The mean overall retentive strength across all 20 pulls was 576.0 N for configuration T1-6, 354.9 N for configuration T1346, 350.7 N for configuration T2345, and 189.9 N for configuration T25. Mean retentive strength also stabilized after the 7th pull for all 4 configurations, resulting in nonsignificant declines in retentive strength within each specific configuration after 7 pulls. Configuration T1-6 exhibited the greatest retentive strength relative to all other configurations both initially and after repeated application of force. Configurations T1346 and T2345 had similar retentive strengths, and both had greater retentive strength than T25. However, despite these differences, all 4 configurations exhibited similar losses in retentive strength from the repeated application of force during the first 7 pulls until stabilization occurred shortly thereafter.

Shear bond strength comparison of implant-retained overdenture attachment pickup materials.

This study evaluated the shear bond strength (SBS) of 4 different retentive materials for the chairside pickup of dental implant attachments. Shear force was applied to determine the SBS of each material to denture acrylic resin. The difference between SBSs of polymethyl methacrylate and UBAR (claimed to bond to metal) to metal housings was also evaluated. There were no statistically significant differences among the SBSs of Jet Denture Repair Acrylic, EZ PickUp, and UBAR, but Quick Up had an SBS that was significantly lower than that of the other 3 materials. In addition, UBAR had a higher SBS to metal housings than did processed polymethyl methacrylate.

Accuracy of dental torque wrenches.

The aim of this in vitro study was to compare the actual torque of 2 manual wrench systems to their stated (target) torque. New spring- (Nobel Biocare USA, LLC) and friction-style (Zimmer Dental, Inc.) manual dental torque wrenches, as well as spring torque wrenches that had undergone sterilization and clinical use, were tested. A calibrated torque gauge was used to compare actual torque to target torque values of 15 and 35 N/cm. Data were statistically analyzed via mixed-effects regression model with Bonferroni correction. At a target torque of 15 N/cm, the mean torque of new spring wrenches (13.97 N/cm; SE, 0.07 N/cm) was significantly different from that of used spring wrenches (14.94 N/cm; SE, 0.06 N/cm; P < 0.0001). However, the mean torques of new spring and new friction wrenches (14.10 N/cm; SE, 0.07 N/cm; P = 0.21) were not significantly different. For torque measurements calibrated at 35 N/cm, the mean torque of new spring wrenches (35.29 N/cm; SE, 0.10 N/cm) was significantly different (P < 0.0001) from the means of new friction wrenches (36.20 N/cm; SE, 0.08 N/cm) and used spring wrenches (36.45 N/cm; SE, 0.08 N/cm). Discrepancies in torque could impact the clinical success of screw-retained dental implants. It is recommended that torque wrenches be checked regularly to ensure that they are performing to target values.

CODA standard 2-24 h-"replacement of teeth" dilemma: Unintended consequences and proposed solutions.

BACKGROUND: The Commission on Dental Accreditation (CODA) was established in 1975 with the goal of serving the public and the dental profession by developing and implementing standards that guide and maintain the quality of dental educational programs. These standards are defined broadly around competencies reflective of an evidence-based definition of general dentistry and that should be met by the new graduates to function as an entry level provider. Consequently, CODA "expects each school to develop specific competency definitions and assessment methods in the context of the broad scope of general dental practice". CODA Standard 2-24 h was implemented a decade ago to address concerns that dental schools are not sufficiently proactive in incorporating implant-related curricula and clinical competencies. When the standard was implemented, most patients already preferred dental implants over FPDs. This market trend, together with the prescriptive format of the standard, had the unintended consequence of creating pressure on programs that struggled to find enough patients who will chose FPDs as a treatment option. DISCUSSION: As a short term solution, we suggest a tooth replacement competency construct that has the potential to alleviate this burden. This solution incorporates principles of ethical decision making, patient-centered care, and evidence-based dentistry, without compromising educational aspects and competency development. For the longer term, we suggested to revise and rephrase the standard so that it will be clinically-centered rather than focused on technical tools that may evolve, change, or disappear as a result of technological progress and other market trends. This, in turn, will be conducive to fulfill the intent of Standard 2-24 to allow the schools to identify "competencies that will be included in the curriculum based on the school's goals, resources, accepted general practitioner responsibilities and other influencing factors."

Analyzing Dental Students' Clinic Production Using Time-Based Relative Value Units: Ten-Year Cross-Cohort Mapping.

The analysis of dental students' clinical production/participation has been used to assess whether a prospective graduate is capable of unsupervised and independent practice (that is, competent to perform that practice). This method and others have inherent biases that may not accurately reflect whether the student has mastered the associated concepts and techniques required for dentistry. The aim of this study was to assess an informatics system that assigned curriculum meta-tags with time-based relative educational value units (ReVUs) to each clinical procedure performed by Medical University of South Carolina (MUSC) students. The system has been used since 1998, but for this study the complete data sets for the MUSC graduating classes of 2007 through 2016 were mapped using microcompetency codes for the dental procedures. In total, 421,494 procedures were formatted and analyzed using software developed to aggregate disparate data sets from clinical activities into a common format for evaluation. The results showed that the ten classes (cohorts) were very consistent with cohort high ReVUs averaging 7,317.1 points, cohort mean ReVUs being 5,180.2 points, and cohort low ReVUs averaging 3,381 points. A detailed analysis of student effort by dental subspecialty found that preventive activities represented 13.4%, patient assessment 32.6%, periodontology 2.8%, restorative dentistry 16.3%, prosthodontics 21.9%, endodontics 6.7%, and oral surgery 5.7% of the total points in the clinical part of the curriculum. In this system, point thresholds can be easily generated to monitor students' progress towards competence for each defined competency and thus assess their progress towards acquiring the skills required for unsupervised, independent practice.

Three-dimensional analysis of dual-arch impression trays.

OBJECTIVE: The objective of this investigation was to measure and compare the dimensions of casts made using four types of impression trays and two impression materials to the dimensions of the original master model. This study differed from previous studies by using three-dimensional measurement. METHOD AND MATERIALS: Vinyl polysiloxane and polyether impressions were made of two crown preparations of ivorine teeth cemented into an acrylic master model. Two grooves were placed into each of the preparations. In addition, six points were placed on each occlusal surface and six were placed on each finish line. Impressions were poured with a Type IV dental stone at 48 hours. A three-dimensional measuring system was used to determine coordinates of 32 points on the master model and resulting casts. Inter- and intratooth dimensions were calculated from the measured coordinates. RESULTS: The accuracy and precision of the impression techniques were assessed using analysis of variance (ANOVA) and Dunnett's t test. The ANOVA and Dunnett's t test indicated that only the custom tray did not detect any inaccuracies and was as reproducible as the master model. CONCLUSION: This study suggests that the custom tray technique is most accurate, even though all other techniques evaluated apparently produce clinically acceptable results.