ABSTRACT
STATEMENT OF THE PROBLEM: An important aspect of dental education is teaching and learning shade matching. OBJECTIVE: To assess the success of two different strategies for learning shade matching. MATERIALS AND METHODS: Seventy-one pre-clinical students (mean age 23; 33.3% men) were divided into two groups. One group (TTB) formed teams of two and they matched three pre-determined teeth on each other using the 3D-Master shade guide. After this exercise, they learned shade matching using a standardized device (Tooth Guide Training Box, TTB) by matching shade tabs in an artificial environment. The other group (GL) matched tooth color in a pre-defined clinical setting in groups of four students. After this, they matched the same teeth as before training, again in groups of two, similarly to group TTB. The reference tooth color was determined by two experienced prosthodontic clinicians. The L*a*b* values for the tabs were provided by the manufacturer and the color difference (ΔE(ab)) between the chosen tab and the reference was calculated. Linear general estimation equation models were used for statistical evaluation (p = 0.05). RESULTS: In the TTB group, the difference between ΔE(ab) values before and after training was 0.03, which was not significant (p = 0.927; 95% CI: -0.70/0.77). In the GL group, ΔE(ab) was 0.98 smaller after training, which was significant (p < 0.001; 95% CI: 0.50/1.50). CONCLUSION: The ability to match tooth color could be improved by using a group-learning approach in a clinical setting and implementation of such a training session should be considered in undergraduate and postgraduate dental education.
Subject(s)
Color/standards , Computer-Assisted Instruction/methods , Dental Restoration, Permanent , Dentistry, Operative/education , Education, Dental/methods , Curriculum , Female , Group Processes , Humans , Linear Models , Male , Prosthesis Coloring/methods , Software , Young AdultABSTRACT
OBJECTIVES: Evaluation of the effect of different span length and preparation designs on the fracture load of tooth-implant-supported fixed dental prostheses (TIFDPs) manufactured from yttrium-stabilized zirconia frameworks. MATERIAL AND METHODS: Forty-eight TIFDPs were manufactured using a CAD/CAM system and veneered with a press ceramic. Rigidly mounted implants (SLA, diameter 4.1 mm, length 10 mm) in the molar region with a titanium abutment were embedded in PMMA bases pairwise with premolars. All premolars were covered with heat-shrink tubing to simulate physiological tooth mobility. Six different test groups were prepared (a) differing in the preparation design of the premolar (inlay [i]; crown [c]), (b) the material of the premolar (metal [m]; natural human [h]) and (c) the length of the TIFDPs (3-unit [3]; 4-unit [4]). All TIFDPs underwent thermomechanical loading (TCML) (10,000 × 6.5°/60°; 6 × 10(5) × 50 N). The load to fracture (N) was measured and fracture sites were evaluated macroscopically. RESULTS: None of the restorations failed during TCML. The mean fracture loads (standard deviations) were 1,522 N (249) for the 3-unit, inlay-retained TIFDPs on a metal abutment tooth (3-im), 1,910 N (165) for the 3-cm group, 1,049 N (183) for group 4-im, 1,274 N (282) for group 4-cm, 1,229 N (174) for group 4-ih and 911 N (205) for group 4-ch. Initial damages within the veneering ceramic occurred before the final failure of the restoration. The corresponding loads were 24-52% lower than the fracture load values. CONCLUSIONS: All restorations tested could withstand the mastication forces expected. Fracture-load values for 3- and 4-unit inlay-crown and crown-crown-retained TIFDPs should spur further clinical investigation.
