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Original Article
Year :  |  Volume : 7   |  Issue :1   |  Page :9-14  

P. Kalyani, M. Dhanraj, Ashish R. Jain

Correspondence Address:Department of Prosthodontics, Saveetha Dental College and Hospitals, Chennai, Tamil Nadu, India

Source of Support: None , Conflict of Interest: None

DOI: 10.4103/2231-4040.197331

How to cite this article:

Kalyani P, Dhanraj, Jain AR. Marginal discrepancy in base metal alloys: A systematic review and meta analysis. J Adv Pharm Edu Res 2017;7(1):9-14.

  Introduction   Top

The marginal fit is one of the most important criteria for long-term success of all-ceramic restorations.[1] When considered clinically, a casting becomes acceptable only when the marginal gap between the prepared tooth and the casting is indiscernible both visually and also while probing. The marginal gap may lead to increased retention of plaque. This changes the distribution of microflora as the marginal gap becomes a protective space for microorganisms. This paves way for secondary caries and periodontal disease. Furthermore, microleakage under the restoration may cause endodontal inflammation and hypersensitivity.[2-4] The marginal fit of restorations is governed by many factors such as perceptive tooth preparation, accurate impressions, type of casting metal used, precision casting, and careful finishing.[3] The crowns and copings are manufactured either from base metal alloys or from noble metal alloys. The base metals commonly used are nickel chromium (NiCr) alloys. The noble metal alloys include Type III gold alloys, gold palladium, silver-palladium alloys, and alumina. When comparing NiCr and gold alloys, the former has extensive physical and mechanical properties, with greater yielding properties and moduli of elasticity.[5] The complete veneer crown is the form of crown restoration done to reproduce the normal tooth contour by artificial materials. Among the metal alloys, CoCr exhibits the best fit at the cervical and incisal areas.[6] The marginal discrepancy also varied when the NiCr crowns covered the occlusal surface and when they didn’t. The marginal discrepancy was found to be higher when they covered the occlusal surface.[7] Ag Pd alloy exhibited the best marginal discrepancy when compare to Type III gold and NiCrMo alloys.[2] Hence, this systematic review was formulated with the following aims and objectives:


The aim of this systematic review is:

• To evaluate the amount of marginal discrepancy in complete veneer crowns fabricated using base metals

• To evaluate the amount of marginal discrepancy in complete veneer crowns fabricated using noble metals

• To compare the marginal discrepancies between base metal and noble metal alloys and to infer the alloy with the least marginal discrepancy.

PICO analysis


Complete cast crown, complete veneer crown, full veneer crown and metal crown.


Base metal alloys, base metal crowns, NiCr crowns, cobalt chromium crowns and titanium crowns.


Gold crowns, noble metal crowns, precious metal crowns, semiprecious metal crowns, Type III gold crowns, Type IV gold crowns, gold platinum crowns, and gold palladium crowns.


Marginal discrepancy, marginal gap, marginal leakage and microleakage.

Variables of interest

Influence of the following factors on marginal discrepancy:

1. Noble metal alloys

2. Base metal alloys.

  Materials and methods   Top

Sources used

An electronic search was initiated for scholarly articles on crowns and bridges, base metal alloys crowns, noble metal alloy crowns, and marginal discrepancy. The search was PubMed based. The search methodology applied was a combination of MESH terms and suitable keywords based on population, intervention, comparision, outcome (PICO) formulated for the review

Search methodology

Suitable keywords were formulated for PICO and subjected to advanced search using Boolean operators.

Selection of studies

The review process comprises two phases. In the first phase, the title and abstracts of the articles obtained through PubMed search were examined for relevance. The full text of relevant articles was obtained and accessed. In the second phase, relevant articles were isolated based on inclusion and exclusion criteria, for further data extraction and statistical analysis.

Inclusion criteria

The articles focusing on the following parameters were included for the systematic review:

• In vitro studies evaluating marginal discrepancy in complete veneer crowns

• In vitro studies reporting marginal discrepancy in cast copings

• In vitro studies discussing the marginal discrepancy in universal post abutments.

Exclusion criteria

The articles discussing the following parameters were excluded from the systematic review:

• Case reports and case series

• Marginal discrepancy in partial veneer crowns

• Studies on inlay or onlay.

The database search yielded 17 articles of which, 6 articles were excluded after reading the abstract. For the remaining 11 articles, full text was accessed and obtained. Of these 11 articles, 6 articles were excluded based on exclusion criteria and 5 were included for the final review. The selected articles were subjected to data extraction. The following data were extracted (Charts 1 and 2):

• Journal

• Authors

• Study design

• Study groups

• Intervention/treatment

• Method of measurement

• Outcome measure - marginal discrepancy

• Statistics

• Inference.

The following data regarding marginal discrepancy were extracted from the selected articles and were tabulated as Table 1.

Name of the journal, author, the design of the study, study groups, the intervention or treatment focused in this study, methods used to measure the marginal discrepancy, outcome measure such as mean marginal discrepancy, statistical test, and inference were extracted and tabulated.

  Results   Top

Discussion   Top

Conclusion   Top

References   Top




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