ORAL HEALTH EVIDENCE-BASED PRACTICE PROGRAM
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Title Conventional Casting Restorations Have a More Precise Fit Than CAD/CAM Milled Titanium Restorations with Respect to a Single-Unit Implant Supported Crown
Clinical Question For a patient who requires a single-unit implant supported crown, will a CAD/CAM milled titanium framework result in a more precise fit than conventional casting?
Clinical Bottom Line For a patient who requires a single-unit implant supported crown, the conventional casting wax technique will result in a smaller vertical marginal gap when compared to a CAD/CAM milled restoration. This is supported by an in vitro laboratory study, which demonstrated that the wax method resulted in statistically significant smaller vertical marginal gaps.
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) 18355167Tan/200820 SamplesLaboratory Study
Key resultsThe authors found that the conventional casting technique resulted in a vertical marginal gap of 23.91 ± 9.8μm while the CAD/CAM restoration had an opening of 79.43 ± 25.46 μm. This difference was found to be statistically significant with a p-value of 1.88 x 10-16.
Evidence Search “Computer-Aided Design” AND “Dental Casting” AND “Titanium” AND “Dental Crown”
Comments on
The Evidence
This was a laboratory study that compared the resulting vertical marginal gaps from conventional casting versus CAD/CAM. The authors created a master die from a right maxillary first molar and took twenty impressions of the master die. Ten impressions were then chosen randomly for conventional casting while the other ten were used for the CAD/CAM method. The authors took care to follow standardized methods throughout the procedure. The copings were then placed on the master die and pictures were taken with a digital SLR camera. Digital measurement software was used to determine the gap, and the average gap of all 4 sides was recorded for statistical analysis. No competing interests were listed.
Applicability Although the difference was statistically significant, the study did not seek to determine whether either of the methods resulted in a final product that was clinically acceptable. The author further states that the absolute value of the vertical marginal gap proposed to be clinically acceptable ranges from 39 to 120 μm. Thus, it is plausible that the CAD/CAM method could be clinically acceptable. Moreover, the study also states that the CAD/CAM milling system has undergone several hardware and software updates since the start of testing. The CAD/CAM system also has several parameters, which can be modified to further optimize the system. These potential improvements could result in a smaller marginal gap. However, given that patients will accept this method and the fact that most dentists are more familiar with the conventional cast technique (along with its lower cost), it still remains a better option. It is important to note that only one in vitro laboratory study was considered for this recommendation.
Specialty/Discipline (General Dentistry) (Prosthodontics)
Keywords CAD, Titanium, Castings, Margin
ID# 2851
Date of submission: 03/30/2015spacer
E-mail sehbi@livemail.uthscsa.edu
Author Indrajit Sehbi
Co-author(s)
Co-author(s) e-mail
Faculty mentor/Co-author E. Matthew Lamb, DDS
Faculty mentor/Co-author e-mail lambem@livemail.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?)
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