ABSTRACT
Statement of the Problem: Mechanical properties of interim restorations are considered as important factors specially when selecting materials for long-term application or for patients with para-functional habits. Flexural strength is one of the most important components of these restorations
Purpose: The purpose of this study was to compare the flexural strength of five interim restorative materials
Materials and Method: Fifty identical samples sized 25×2×2-mm were made from five interim materials [TempSpan; Protemp 4, Unifast III, Trim, and Revotek LC] according to ADA specification #27. The specimens were stored in artificial saliva for 2 weeks and then thermocycled for 2500 cycles [5-55?C]. A standard three-point bending test was conducted on the specimens with a universal testing machine at a crosshead speed of 0.75mm/min. Data were analyzed by using one-way ANOVA and Tamhane's post-hoc tests to measure the flexural strength of temporary materials
Results: One of the bis-acryl resins [TempSpan] showed the highest, and the light polymerized resin [Revotek LC] showed the lowest flexural strength. The mean values of flexural strength [MPa] for the examined materials were as follow: Temp- Span=120.00, Protemp 4=113.00, Unifast III=64.20, Trim= 63.73 and Revotek LC=47.16. There were significant differences between all materials except Trim and Unifast III which did not show any statistical significant difference
Conclusion: Bis-acryl resins were statistically superior to traditional methacrylate and light-cured resins. Therefore, application of bis-acryl resins should be deliberated in patients with heavy occlusion and in cases that need long-term use of interim restorations
ABSTRACT
The early computer-aided design/computer-aided manufacturing [CAD/CAM] systems were relied exclusively on subtractive methods. In recent years, additive methods by employing rapid prototyping [RP] have progressed rapidly in various fields of dentistry as they have the potential to overcome known drawbacks of subtractive techniques such as fit problems. RP techniques have been exploited to build complex 3D models in medicine since the 1990s. RP has recently proposed successful applications in various dental fields, such as fabrication of implant surgical guides, frameworks for fixed and removable partial dentures, wax patterns for the dental prosthesis, zirconia prosthesis and molds for metal castings, and maxillofacial prosthesis and finally, complete dentures. This paper aimed to offer a comprehensive literature review of various RP methods, particularly in dentistry, that are expected to bring many improvements to the field. A search was made through MEDLINE database and Google scholar search engine. The keywords; 'rapid prototyping' and 'dentistry' were searched in title/abstract of publications; limited to 2003 to 2013, concerning past decade. The inclusion criterion was the technical researches that predominately included laboratory procedures. The exclusion criterion was meticulous clinical and excessive technical procedures. A total of 106 articles were retrieved, recited by authors and only 50 met the specified inclusion criteria for this review. Selected articles had used rapid prototyping techniques in various fields in dentistry through different techniques. This review depicted the different laboratory procedures employed in this method and confirmed that RP technique have been substantially feasible in dentistry. With advancement in various RP systems, it is possible to benefit from this technique in different dental practices, particularly in implementing dental prostheses for different applications