Dental laboratory communication regarding removable dental prosthesis design in the UAE.

PURPOSE: The purpose of this study was to determine the methods dental practitioners in the United Arab Emirates (UAE) use to communicate cast removable dental prosthesis (RDP) design to dental laboratories; identify common practices taken by dentists/dental technicians prior to fabrication of RDP framework; and seek out dental technicians' attitudes toward their role in RDP design decisions. MATERIALS AND METHODS: All dental laboratories (n = 28) listed in a local telephone directory were invited to complete a questionnaire through a face-to-face interview. They were also requested to examine RDP cases fabricated in the past 2 months and identify steps taken by dentists/dental technicians prior to fabrication of the framework. Descriptive statistics were used to report frequencies and percentages. RESULTS: Twenty-one (75%) dental laboratories agreed to participate, out of which 19 had the facilities to fabricate chrome-cobalt RDPs. Cast RDPs comprised approximately 4.04% (±2.67) of services provided. A reported 84.2% of dentists frequently communicate through generic lab script, with 89.5% rarely/never giving details regarding RDP design. While 52.6% of labs agree/strongly agree that it is the dentist's responsibility to decide the final RDP design, 94.7% agree/strongly agree that dentists should depend on dental technicians for design-making decisions. A total of 19 RDP cases were reviewed. All 19 were surveyed and designed by dental technicians but received dentist approval of design prior to fabrication. Thirteen (68.4%) had rest-seat preparations done by dentists after approval, and new impressions sent to the lab. No other tooth modifications were noted. CONCLUSION: The responsibility of RDP design appeared to be largely delegated to dental technicians. Importance of tooth modifications seemed to be undervalued and not completed prior to framework fabrication.

Fracture strength of three all-ceramic systems: Top-Ceram compared with IPS-Empress and In-Ceram.

PURPOSE: The purpose of this study was to investigate the fracture loads and mode of failure of all-ceramic crowns fabricated using Top-Ceram and compare it with all-ceramic crowns fabricated from well-established systems: IPS-Empress II, In-Ceram. MATERIALS AND METHODS: Thirty all-ceramic crowns were fabricated; 10 IPS-Empress II, 10 In-Ceram alumina and 10 Top-Ceram. Instron testing machine was used to measure the loads required to introduce fracture of each crown. RESULTS: Mean fracture load for In-Ceram alumina [941.8 (± 221.66) N] was significantly (p > 0.05) higher than those of Top-Ceram and IPS-Empress II. There was no statistically significant difference between Top-Ceram and IPS-Empress II mean fracture loads; 696.20 (+222.20) and 534 (+110.84) N respectively. Core fracture pattern was highest seen in Top- Ceram specimens.

Educational necessities to compensate for faculty shortage.

The purpose of this investigation was to evaluate whether senior dental students (4DS) could serve as effective instructors in a two-semester preclinical laboratory course and whether such teaching experience could enhance their interest in academics as a future career. Based on academic performance, five senior students were recruited to serve as instructors in a two-semester morphology/occlusion laboratory course in which ninety-five first-year dental students were enrolled. The first-year students were randomly assigned so that each student was instructed by a faculty member in one semester and a 4DS in the other semester. Outcomes included course evaluation forms completed by the first-year dental students at the end of each semester; a comparison of students' performances in each course determined by faculty instructors and 4DSs; and the 4DSs' self-report of their teaching experiences. Results showed no significant difference between the performance of 4DS and faculty instructors in all criteria evaluated (p>.05). Furthermore, there was no significant difference between the performance of students instructed by faculty members and those instructed by 4DS in either semester (p>.05). Despite the fact that such experience seemed to have minimal influence on students' decision to consider academics as a future career, 4DSs do seem to provide effective instruction and thereby can serve to compensate for faculty shortages.

Influence of environmental conditions on dental composite flexural properties.

OBJECTIVE: To determine if increased relative humidity and temperature simulating intraoral environmental conditions adversely affect flexural properties of dental composites. METHODS: Specimen fabrication followed ANSI/ADA specification 27 for resin-based filling materials, except that ambient laboratory conditions (47% relative humidity at 22 degrees C) or simulated intraoral conditions (90% relative humidity at 35 degrees C) were used when fabricating and polymerizing specimens. Ten specimens were made of each of three commercially available composites at each condition. As per the specification, after aging specimens in 10 ml of deionized water at 37 degrees C for 24 h, flexural properties were measured using a 3-point bend test. RESULTS: A two-factor ANOVA and Fisher's least significant difference (LSD) post hoc (alpha=0.05) indicated there were significant differences in flexural modulus and strength as a function of material, with Z250=TPH>Prodigy. However, neither flexural modulus nor flexural strength of any material was adversely influenced by fabrication conditions. SIGNIFICANCE: Although the flexural properties did not decrease with respect to fabrication conditions, the flexural modulus of some of the materials (TPH Spectrum and Z250) increased when specimens were fabricated at simulated intraoral temperature and relative humidity. Thus, simulation of these factors may be important in laboratory testing, since the resultant properties may better reflect flexural properties associated with dental composite restorations placed clinically.

Rater reliability: short- and long-term effects of calibration training.

The purpose of this investigation was to evaluate the immediate effects of calibration on inter-rater agreement to a gold standard (GS) and to determine whether the effects can be sustained over a ten-week period. Valid criteria for a Class II amalgam preparation, a three-point rating scale, and a grade form were developed. Three tests were administered: prior to calibration training, immediately following training, and ten weeks later. Each test consisted of faculty independently evaluating ten prepared teeth. Agreement with GS scores for most of the grading criteria improved as a result of training and did not deteriorate over time. The overall percent agreement was 54.5, 66.9, and 64.6 percent across test periods. The most impressive gains in agreement occurred when the criteria evaluated had a GS score of either "standard not met" or "ideal." There was very little gain when the gold standard score was "acceptable." It is concluded that, with training, inter-rater agreement with a gold standard can improve and such improvement is reasonably resistant to deterioration after ten weeks. Nevertheless, future training ought to consider the use of a mastery approach in calibration training to ensure that a satisfactory degree of agreement with the GS is obtained.

Utilization of evidence-based informational resources for clinical decisions related to posterior composite restorations.

The purpose of this study was to characterize evidence-based informational resources utilization patterns of a sample of general dentists with respect to clinical decisions regarding posterior composite restorations. A stratified random sample of general practitioners belonging to the Academy of General Dentistry (n = 2880) was mailed a questionnaire that elicited information about practice characteristics and informational resources used for clinical decision making related to posterior composite restorations. Six hundred ninety-nine dentists responded (24 percent response rate). Use of evidence-based (EB) resources (journals and online data bases) was low for all respondents (14 percent) for all levels of experience; however, more experienced clinicians were more likely to use EB resources than recent graduates. AGD Master-level members were significantly more likely to use EB resources than their counterparts (p < .05). Within the limitation of this study, current patterns suggest a low reliance on evidence-based informational resources in the practice of clinical dentistry.

Survey of general dentists regarding posterior restorations, selection criteria, and associated clinical problems.

This survey was designed to provide insight concerning the materials that general dentists use for direct and indirect posterior restorations. A stratified random sample of dentists (n = 2,880) from the Academy of General Dentistry's membership list received a questionnaire that elicited information on the clinician's current use of amalgam, direct, and indirect composite materials; reasons for material selection; and reported complications with composite restorations. Data were analyzed using descriptive statistics as well as t-test, Mann-Whitney, and chi square for group comparisons. A total of 714 dentists (26.3%) responded. Direct composite was the material used most commonly for posterior intracoronal restorations. Dentists in amalgam-free practices (31.6%) were significantly more likely (p = 0.001) to use direct composite than dentists whose practices used amalgam. Both groups weighed clinical decision factors and ranked perceived complications differently. Dentists in amalgam-free practices were less likely (p = 0.001) to consider caries rate, patient demand, and moisture control as important clinical decision factors and were more likely to report never experiencing complications.

Team-based learning in a preclinical removable denture prosthesis module in a United Arab Emirates dental school.

The purpose of this article is to describe the implementation of a team-based learning (TBL) approach in a removable denture prosthesis (RDP) module and present the results of students' performance in individual and group TBL activities and exam scores, students' experience with TBL and end of course evaluations, and faculty feedback. Course material at the College of Dentistry, University of Sharjah, United Arab Emirates, was transformed into seven conventional lectures and seven TBL sessions. Each TBL session consisted of pre-assigned reading (self-directed learning), in-class individual and group readiness tests (accountability), team problem-solving of patient RDP cases, and faculty-led class discussion (knowledge application). The course was assessed through scores from TBL session activities and course examinations, student satisfaction survey, and faculty feedback. Course grades were found to be higher using the TBL method then the traditional lecture-based method. Student evaluation data and faculty response indicated strong support for TBL as it was implemented in the course. The faculty noted a higher level of student engagement with team learning than in conventional class lecturing. TBL is an active-learning instructional strategy for courses with high student-to-faculty ratios. This approach provides regular feedback and the opportunity for students to develop higher reasoning skills.

Histomorphologic characterization of noncarious and caries-affected dentin/adhesive interfaces.

PURPOSE: The purpose of this study was to compare the dentin/adhesive interfacial characteristics when bonding to noncarious as well as caries-affected dentin. MATERIALS AND METHODS: Seven extracted, unerupted, third molars were sectioned into halves. Artificial caries was created on one-half of each tooth, leaving the other half as a control. Dentin surfaces were treated with UNO adhesive according to the manufacturer's instructions for the wet-bonding technique and under environmental conditions present in the oral cavity. Dentin/adhesive interface sections of each half-tooth were stained with Goldner's trichrome, a classic bone stain, and examined using light microscopy. The width of exposed collagen was measured directly from photomicrographs, and adhesive penetration was analyzed qualitatively. RESULTS: The degree and extent to which the adhesive encapsulated the demineralized dentin matrix were reflected in the color difference in the stained sections with the noncarious dentin sections showing a degree of collagen encapsulation superior to that of the caries-affected dentin sections. The overall mean widths of exposed collagen were significantly (p < or = .05) greater at the caries-affected dentin/adhesive interface, 8.6 (1.7) microm, as compared with those at the noncarious dentin/adhesive interface, 6.0 (1.5) microm. CONCLUSIONS: The morphologic characteristics of the caries-affected dentin/interface suggest an increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration when compared with noncarious dentin. The evidence suggests that dentin substrate characteristics have a significant effect on the dentin/adhesive interface structure.

Moisture effect on polyether and polyvinylsiloxane dimensional accuracy and detail reproduction.

PURPOSE: This investigation evaluated and compared the dimensional accuracy and surface detail reproduction of two hydrophilic polyvinylsiloxane (PVS) and two polyether (PE) impression materials when used under dry and moist conditions. METHODS: Impressions were made of stainless steel dies as described in ANSI/ADA specification no. 19, with two vertical and three horizontal lines inscribed on the die superior surface. Impressions were made under dry and moist conditions (17 impressions per condition for each material). Dimensional accuracy was measured by comparing the average length of the middle horizontal line in each impression with the same line on the metal die using a measuring microscope with an accuracy of 0.001 mm. Surface detail reproduction was evaluated by using criteria similar to ADA specification no. 19: continuous replication of at least two of the three horizontal lines. RESULTS: The mean percent dimensional change and SD values ranged from -0.135% (0.035) to 0.053% (0.031). A two-way analysis of variance (ANOVA) indicated that moisture did not cause significant adverse effects on the dimensional accuracy of any material (p > 0.05); however, significant differences were found between the materials (p < .05). The surface detail evaluation indicated that moisture had a significant effect on detail reproduction of PVS materials (Pearson's Chi square, p < 0.05). Under dry conditions, all materials produced satisfactory detail reproduction 100% of the time; however, under moist conditions, only 29% of Aquasil and Genie Ultra PVS impressions produced satisfactory detail reproduction, while 100% of Permadyne Garant and Impregum Penta Soft PE impressions still met the surface detail criteria. CONCLUSIONS: Although moisture may not adversely affect the dimensional accuracy of either PE or hydrophilic PVS material, the evidence suggests that PE material is more likely to produce impressions with superior detail reproduction in the presence of moisture.

A provisional fixed partial denture that simulates gingival tissue at the pontic-site defect.

A technique is presented for the fabrication of an esthetic, provisional fixed partial denture that compensates for a pontic-site ridge defect. This provisional restoration enables both the dentist and the patient to evaluate whether this prosthetic approach will adequately camouflage the pontic-site defect or whether surgical correction of the pontic site should also be considered.