UTCAT626, Found CAT view, CRITICALLY APPRAISED TOPICs

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Title

Working Die Made From Metal Dual-Arch Tray and Plastic Dual Arch Tray

Clinical Question

Is the dimensional accuracy of die generated from metal dual-arch tray better than plastic dual-arch tray?

Clinical Bottom Line

The plastic dual tray is more accurate buccolingually than the metal dual-arch tray. However, mesiodistally, metal dual-arch are slightly more accurate than the plastic ones. (See Comments on the CAT below)

Best Evidence

(you may view more info by clicking on the PubMed ID link)

PubMed ID	Author / Year	Patient Group	Study type (level of evidence)
#1) 12942055	Ceyhan/2003	Eight patients requiring a posterior single tooth implant restoration were selected	RCT
Key results	There were no significant differences in die accuracy among the 3 trays for the mesiodistal (3.507 mm) and occlusogingival (3.584 mm) dimensions of the implant abutment. Dies were smaller than the standard for these 2 dimensions and larger in the buccolingual dimension. There was a significant difference in accuracy between the metal and plastic dual-arch trays. The dies produced from the metal dual-arch tray were 20 micron larger than the abutment standard compared with 3 micron larger for the plastic tray. The occlusogingival dimension of the working dies was 30 to 40 micron shorter than the implant abutment. Seven of the 8 patients ranked the plastic dual-arch impression as the most comfortable and the complete-arch custom tray as the least comfortable. CONCLUSIONS: Within the limitations of this study, the dimensions of working dies from a custom tray impression did not differ significantly from those created with dual arch trays. However, working dies from a plastic dual-arch tray were more accurate buccolingually than those from metal dual-arch trays.
#2) 12886207	Ceyhan/2003	Impressions were made of a typodont mandibular arch containing a circular stainless steel crown	RCT
Key results	Statistically significant differences were found with viscosity selection for the buccolingual and occlusogingival dimensions of the working die. The rigid material produced working dies slightly taller (1 micron) than the standard, and those from the monophase material were 4 micron shorter. Regarding tray selection, metal trays were slightly more accurate in the mesiodistal dimension, and when monophase was used in a plastic tray, gypsum dies were nearly 30 micron smaller in the mesiodistal dimension (P<.05). Differences were not detected for sequence of pouring impressions. Within the limitations of this study, the monophase material, when compared with the rigid impression material, was most accurate for the occlusogingival and mesiodistal dimensions, although not as accurate in the buccolingual. This buccolingual difference (0.002 mm-0.006 mm) would be clinically inconsequential with the application of die spacer. The rigid impression material was also unaffected by tray selection for the mesiodistal, whereas monophase was affected. When a monophase impression material was used, plastic dual-arch trays yielded gypsum dies which were significantly smaller (0.029 mm) than the ones generated from the metal trays (0.006 mm). Thus rigid impression materials can be recommended for use in dual-arch trays; however, the magnitude of the differences would generally not be clinically significant because they could be compensated for with several coats of die spacer.

Evidence Search

Limits: Randomized Controlled Trial, Search plastic dual arch trays Limits: Randomized Controlled Trial, Search plastic dual arch trays Limits: Meta-AnalysisSearch plastic dual arch trays, Search metal dual arch tray Search die

Comments on
The Evidence

Groups were similar at start, more than 90% comparison. Adequate follow up is not enough. Groups treated differently. They were double blind. No competing interest.

Applicability

By choosing the more accurate dual arch tray the working die would be more accurate dimensionally and we will get a better outcome.

Specialty/Discipline

(General Dentistry) (Prosthodontics) (Restorative Dentistry)

Keywords

ID#

626

Date of submission:

04/02/2010

E-mail

salim@uthscsa.edu

Author

Nasim Salim

Co-author(s)

Co-author(s) e-mail

Faculty mentor/Co-author

Barry K. Norling, MS, PhD

Faculty mentor/Co-author e-mail

NORLING@uthscsa.edu

Basic Science Rationale (Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)	post a rationale
None available

Comments and Evidence-Based Updates on the CAT
(FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs)

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