To compare the accuracy of post and cores created with three different fabricating techniques: direct conventional, machine milling, and three-dimensional (3D) printing. Materials and methods:Thirteen extracted single root central incisors were selected. Root canal treatment and tooth preparation for crown were performed on all teeth. Post space preparation of 11 mm was created using prefabricated fiber post drill to standardize post space width and length. Root canal impressions were performed on all teeth using polyvinyl siloxane impression material. Each impression was then three dimensionally scanned using an extraoral lab scanner. The scanned impressions were used to design digital files of post and cores with 3Shape CAD software. The digitally designed post and cores were used to fabricate 3D printed and milled post and core resin patterns. The same teeth were used to fabricate post and core with conventional technique (direct duplication of root canal with resin pattern). All posts were then scanned before being invested and then cast using base metal educational alloy. The metal post and cores were tried in with sample teeth and manually adjusted until found to be clinically acceptable. The post and cores were scanned in different stages to perform digital volume measurement using Geomagic Control software to determine accuracy. Pairwise comparisons were accomplished using exact version of the sign test (α = 0.05). Results: These three techniques of post and core fabrication showed different results in the various stages of fabrication. The accuracy of 3D printed resin pattern (26.89 ±11.09 mm 3 ) was found to be inferior compare to milled resin pattern (28.20 ±11.41 mm 3 , p = 0.0002). However, dimensional stability of the 3D printed resin pattern before and after casting (0.56 ±0.95 mm 3 ) was found to be superior to milled resin pattern (0.79 ±0.89 mm 3 ) and direct resin pattern (2.51 ±1.38 mm 3 , p = 0.00002). All three techniques showed significant volume reduction after adjustment (p = 0.0002). In the final stage, the adjusted metal post and core fabricated with three different techniques showed no statistical different in accuracy (p = 0.15). Conclusion: Digitally fabricated post and cores have the same degree of accuracy as those fabricated using the gold standard direct conventional post and core technique. K E Y W O R D S3D printing, 3D milling, accuracy of post and core, customized post and core, post and core
The purpose of this research was to compare the accuracy of threedimensionally (3D) printed post and core fabricated with two different materials: reinforced wax and castable resin. Materials and methods:Fifteen extracted single root central incisors were selected. Root canal treatment and tooth preparation for crown were performed on all teeth. Eleven millimeters post space was created with standardized prefabricated fiber post drill. Polyvinylsiloxane impression material was used for root canal impressions. Each impression was then 3D scanned using an extraoral scanner and cast posts and cores were designed using 3Shape software. The digitally designed post and cores were 3D printed with two different materials: castable wax resin and castable resin. The castable resin patterns were scanned before and after complete polymerization. The wax patterns were also scanned. Digital volumetric measurement using Geomagic® Control X™ software was performed to determine accuracy. Results: The printed post and core had reduced volume (16.09 ± 3.839 mm 3 ) compared to the digital design (17.828 ± 3.904, p < 0.05). Before complete polymerization, the accuracy of 3D printed resin pattern (16.464 ± 3.017) was found to be superior to post and core printed with wax (16.193 ± 3.018, p < 0.05). However, no volume difference was found between completely polymerized resin (16.09 ± 3.839) and wax (16.044 ± 3.834, p = 1). Conclusion: 3D printed post and core showed significant volume shrinkage from the digital files used to create them. However, different materials had no effect on the accuracy of 3D printed post and core. K E Y W O R D S3D printing, accuracy of post and core, customized post and core, post and core 540
Objectives: The purpose of this study was to evaluate the effect of different medicaments and root canal irrigation technique on dentinal tubule penetration of the resin cement and push-out bond strength of fiber post cemented with self-adhesiveresin cement. Materials and Methods: Ninety mandibular premolars were mechanically instrumented until the apical size matches ISO 40. The specimens were divided into three groups based on medicaments; control (no medication), calcium hydroxide (CH), and triple antibiotic paste (TAP). The medicated groups were subdivided into 4 groups according to final irrigation techniques including conventional needle irrigation (CNI), sonic (SI), ultrasonic (PUI), and XP-endo finisher (XP). The specimens were cemented with RelyX U200 self-adhesive resin cement and were cross-sectioned to observe dentinal tubule penetration using confocal laser scanning microscope and perform push-out bond strength tests. The statistical evaluation was performed using One-Way ANOVA and Duncan’s post hoc test. Results: The CNI group showed significantly lower levels of penetrated resin cement and bond strength compared to the control group in both CH and TAP groups (p < 0.05). No significant differences were observed when ultrasonic and XP-endo finisher were used for root canal irrigation (p > 0.05). Conclusions: Medicaments can decrease the bond strength and penetration of resin cement into the dentinal tubules. Using agitated irrigation methods during final irrigation can enhance the cement adhesion and penetration. Clinical Relevance: Agitated irrigation methods such as PUI and XP can improve resin cement adhesion after medication.
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