Temporary Crown Material Research Articles

Effect of Different Temporary Crown Materials and Surface Roughening Methods on the Shear Bond Strengths of Orthodontic Brackets

The aim of this study was to evaluate the effect of different temporary crown materials (TCMs) and surface roughening methods on the shear bond strength (SBS) of orthodontic brackets. TCMs are widely used during orthodontic treatment in teeth in need of prosthetic treatment, to prevent damage to the final restoration. However, there is no consensus considering the best method for roughening of the surface of TCMs. Five different TCMs [Dentalon Plus-(D), Basworth Trim II-(B), Voco Structure Premium-(V), 3M ESPE Protempt 4-(P), and Revotek LC-(R)] were used in this study. Different surface roughening methods (37% phosphoric acid, sandblasting, and Er:YAG laser) were employed in three subgroups (n=20). The SBS test was used to assess the durability of all groups. Scanning electron microscopy (SEM) analysis was performed on a representative specimen in each group. The highest mean SBS value was observed in group V, followed by groups D and P, regardless of the surface treatment. The lowest SBS values were observed in group B. The laser-irradiated groups had higher SBS values than the sandblasted and acid-etched groups. Furthermore, a significant difference in SBS values was observed between the laser-irradiated group V and all other groups (p<0.005). The effects of the chemical nature of TCMs on the SBS values appeared to be clinically negligible, whereas the type of surface treatments had a significant influence on bond strengths. Er:YAG laser irradiation caused a significant increase in bond strength between the TCMs and orthodontic brackets.

Fracture Resistance of Various Temporary Crown Materials

The aim of this study was to evaluate the fracture resistance of various provisional crown materials using an in vitro model test system. In the present study polycarbonate crowns, prefabricated by the manufacturer (3M Polycarbonate Crown), and the temporary crowns, fabricated in the dental laboratory environment, were fabricated using bis-acryl composite (Protemp II), autopolymerizing PMMA resin (BISICO Temp S), and heat-polymerized PMMA resin (Major C&B-V Dentine). All temporary crowns were stored in distilled water for 24 hours at room temperature prior to testing. The crowns were seated on metal dies, fabricated from Cr-Co alloy (AZ Dental, Konstanz, Germany), and then tested using the indenter of a Hounsfield testing machine (Hounsfield Tensometer, Hounsfield Test Equipment, Raydon, England). The tip of the indenter was located at a position one-third of the way down the inciso-palatine surface at 135 masculine. The data were statistically analyzed for differences using one-way analysis of variance (ANOVA) and the Tukey HSD test (P < .05). Additionally, the types of failure obtained from the fracture load test were examined using 10x magnification with a stereo microscope. The results of the present study indicated polycarbonate crowns were significantly different from the BISICO Temp S, Protemp II, and Major C&B-V Dentine (P < .05) groups. This in vitro study shows polycarbonate crowns may be preferable to the other types of temporary crowns used in this study.

The effects of two temporary crown materials on the dental pulp of monkeys (Macaca fascicularis).

Summary. A method for testing the pulpal response to temporary crown and bridge materials is described. The histological evaluation shows that neither test nor control material produced pulpal irritation over periods up to 4 weeks.

The Desirability of Using Radiopaque Plastics in Dentistry: A Status Report

Radiopacity in dental plastic materials is desirable. Currently, only radiopaque composite restorative materials and one temporary crown material are commercially available. Developments in incorporating radiopacity in other dental polymeric materials should be encouraged. Also, research should be conducted to quantify and standardize radiopacity both in materials and their clinical utilization. No requirement of radiopacity is currently included in any ANSI/ADA Specification applicable to dental plastic materials. However, standard test methods (ASTM Standard F640-79) have been established for radiopacity of plastics for medical use. The Council on Dental Materials, Instruments, and Equipment recommends that appropriate subcommittees of the American National Standards Committee MD156 develop, as quickly as possible, requirements and appropriate test methods to be placed in future revisions of standards covering plastics in dentistry.