Objectives:This in vitro study evaluated the shear bond strength (SBS) of resin composite to feldspathic porcelain after acidulated phosphate fluoride (APF) gel treatment over different periods of time.Methods:One hundred and fifty-six feldspathic specimens were divided into 12 groups. Group C received no treatment (control group). Groups APF1 through APF10, ten experimental groups, were treated with 1.23% APF gel. Each group obtained 1 to 10 minutes of etching time in 1 minute increments, respectively. Group HF2 was treated with 9.6% hydrofluoric acid (HF) for 2 minutes. All specimens were then bonded to a resin composite cylinder using Adper Scotchbond Multi-purpose (3M ESPE) after silane (Monobond-S, Ivoclar Vivadent AG) application. Specimens were stored at 37ºC for 24 hours before the SBS was performed and were recorded in MPa at fracture. Data were analyzed using one-way ANOVA and Tukey’s test (α=.05).Results:HF etching yielded the highest SBS (18.0 ± 1.5 MPa), which was not significantly different from APF gel etching for 6 to 10 minutes (16.0 ± 2.1 to 17.2 ± 1.6 MPa) (P>.05).Conclusions:APF gel etching for 6 minutes might be used as an alternative etchant to HF acid for bonding resin composite to silanized feldspathic porcelain.

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The shortened preclinical didactic and laboratory exercises in prosthodontics at HSDM affect student anxiety, but not their didactic and clinical performances or their decisions in choosing their graduate program. Problem-based learning (PBL) tutorials help the students to integrate preclinical and clinical knowledge and skills in prosthodontics.

Problem-based learning (PBL) was implemented into the dental curriculum at the Harvard School of Dental Medicine (HSDM) in 1994 with an expectation that this pedagogy would enhance students' critical thinking and communication skills as well as general professional competencies. Previous studies have described several aspects of the outcome of PBL curricula at the predoctoral level. However, there is no information available on the perceptions and performance of PBL graduates during their postdoctoral training in dentistry. The purpose of this study was to evaluate the effect of PBL methodology on the performance of HSDM graduates during their postdoctoral training in comparison with their non-HSDM (traditional) co-residents. Surveys containing traditional knowledge-based criteria, preclinical and clinical criteria, and PBL criteria were sent to HSDM graduates from the classes of 2002 through 2004 who were in postgraduate training programs. The HSDM and traditional graduates were asked to evaluate and compare their performance in selected areas with those of their co-residents from either a PBL curriculum or a traditional curriculum. The directors of each program were also asked to assess HSDM graduates relative to other graduates in the program based on the same aspects. Overall, HSDM graduates rated themselves more highly than non-HSDM graduates on all competencies. No significant difference between HSDM and non-HSDM responses was found in general dental knowledge, specialty specific knowledge, preclinical skills, clinical skills, communication with staff, and patient education, whereas significant differences (p<0.05) were found for communication with patients, critical thinking, independent learning, performance in small group settings, self-assessment, and teamwork. The data obtained from the program directors revealed corresponding results. The HSDM graduates' capacity for independent learning was rated as "excellent" by 65.31 percent of the directors and 80.95 percent of the HSDM graduates themselves. These findings suggest that the performance of HSDM graduates during their postdoctoral training met expectations and were similar to non-HSDM graduates for traditional residency program competencies. However, the PBL training appears to provide HSDM graduates with enhanced abilities in independent learning, communication, and cooperation skills.Dr. Thammasitboon is an Instructor,

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The Harvard School of Dental Medicine (HSDM) introduced problem-based learning (PBL) into the dental curriculum in 1994 as a part of curriculum reform. During the reorganization, departments were consolidated, and courses were taught in an interdisciplinary fashion rather than in a discipline-based approach. The changes required a reduction in lecture and preclinical clock hours, which might have affected student performance and anxiety levels. The objectives of this study were to 1) compare the HSDM didactic and laboratory preclinical hours in Endodontics, Operative, and Prosthodontics before and after PBL implementation; 2) compare the HSDM didactic and laboratory preclinical hours in Endodontics, Operative, and Prosthodontics with other schools nationwide; 3) measure students' perceptions of their levels of stress and self-confidence at two time points during their preclinical and clinical years; 4) investigate the correlation between the number of preclinical hours and the students' stress level and self-confidence; and 5) evaluate the impact of shortened preclinical hours on the performance of HSDM students on the National Board Dental Examination Parts I and II. A survey regarding the students' level of stress, self-confidence, and preparation to treat patients during preclinical laboratory exercises was distributed to the HSDM classes of 2005 and 2006 (n=70). The HSDM preclinical curriculum hours were compared to national data as reported by the American Dental Association (ADA). Cross-tabulations were constructed, and the Fisher's exact test was conducted to examine the relationships between the variables. We found that HSDM preclinical hours in Endodontics, Operative, and Prosthodontics were significantly lower than at other schools. During the preclinical exercises, the Prosthodontics preclinical exercises were found to be the most stressful and provided the lowest self-confidence in treating patients as compared to the other preclinical subject areas. HSDM students' scores on the National Board Part I and II examinations continue to be among the highest in the nation and have not been affected by the change in curriculum. We conclude that the change in HSDM's curriculum that resulted in targeted, shorter preclinical exercises has not affected clinical and didactic outcomes, but may have affected the anxiety that students feel when entering the clinic.Dr. Sukotjo is an Instructor,

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Aim:To investigate the fracture resistance of restored endodontically treated teeth (RETT) with fiber posts, cores, and crowns with limited ferrules.Materials and Methods:Sixty maxillary anterior teeth were endodontically treated and decoronated 2 mm above the cemento-enamel junction, and then divided into 6 groups of 10 teeth each; Group circumferential ferrule (2FR), Group ferrule in the labial, mesial, and palatal region (2FR-LaMPa), Group ferrule in the labial, and palatal region (2FR-LaPa), Group 2FR-Pa and 2FR-La respectively, and Group 0FR (no ferrule). All 60 prepared teeth were then restored with quartz fiber posts, resin composite cores, and metal crowns. The specimens were subjected to load until failure occurred. Data were analyzed using one-way analysis of variance and Tukey's tests (α = 0.05). The mode of failure was determined under a stereoscope.Results:A statistical significant difference was found among groups 2FR-LaMPa, 2FR-Pa, 2FR-LaPa, and 2FR from the group 2FR-La, and from the group 0FR (P < 0.01). The predominant mode of failure was an oblique palatal to labial root fracture for the groups with remaining ferrules.Conclusion:For RETT that have incomplete crown ferrules, the location of the ferrules may affect their fracture resistance.