Dr Naisargi Shah, Dr Praveen Badwaik, Dr Vidhi H Sheth, Dr Vishrut Bhatnagar, Dr Nikhil Bhanushali, Dr Prashant Patil
Professor and Head of Department,
Professor,
Post-graduate Student,
Reader,
Lecturer,
Department of Prosthodontics, Crown & Bridge,
Reader
Department of Public Health Dentistry.
T.P.C.T’s Terna Dental College, Navi Mumbai
ABSTRACT :
Purpose : This scoping review aimed to evaluate the effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal copings fabricated using computer-aided designing and computer-aided manufacturing (CAD-CAM) technology.
Material and Methods : The Arksey and O’Malley methodological framework has been followed for this scoping review. The research question and the PIO criteria were established accordingly. An electronic search of the PubMed database for articles published from 1st January 2010 to 31st July 2020 was conducted using a combination of MeSH terms and free-text terms.
Results : 9 articles were eventually identified after applying the inclusion and exclusion criteria and were included in this scoping review. A better overall marginal adaptation was reported in deep chamfer finish line preparation followed by shoulder and chamfer finish line preparations respectively, whereas a better overall internal adaptation was reported in shoulder finish line preparation as compared to chamfer and deep chamfer finish line preparations.
Conclusions : Different finish line preparations and the CAD-CAM method of fabrication seem to influence the marginal and internal adaptation of single-unit tooth-supported cobalt-chromium metal copings. A more detailed search of the available literature is required, preferably a systematic review and meta-analysis, to come to a more definitive conclusion regarding the effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal copings fabricated using CAD-CAM technology.
Keywords : Finish line preparations, chamfer, deep chamfer, shoulder, rounded shoulder, marginal adaptation, internal adaptation, cobalt-chromium metal copings, CAD-CAM technology.
Citations : Shah N, Badwaik P,Sheth V,BhatnagarV, Bhanushali N, Patil P.Effect of different finish line preparations on the marginal and internal adaptation of cobalt - chromium metal copings fabricated using CAD CAM technology - A Scoping Review. J Prosthodont Dent Mater 2020;1(1&2): 3-9.
INTRODUCTION
The advent of computer-aided designing and computer-aided manufacturing (CAD-CAM) technology has greatly improved the efficiency and accuracy of prosthetic treatment when compared to conventional methods.One of the most widely used applications of this technology in the dental field has been in the manufacturing of cobalt-chromium metal copings for fixed dental prosthesis. These are one of the most widely used materials today due to their high strength, good esthetic results, and longevity.
The success of these prostheses greatly depends upon their marginal and internal adaptation, amongst other factors. Marginal adaptation has been considered as the distance between the finish line preparation and the coping margin. The internal adaptation has been considered as the distance between the intaglio surface of the coping and the axial and occlusal surface of the prepared tooth. The presence of discrepancies in this adaptation can lead to increased plaque accumulation, alterations in the distribution of microflora, and gingival irritation.
This can further contribute to a higher risk of dental caries, possibly leading to secondary decay, followed by endodontic complications, leading to eventual failure of the prosthesis.5,6 Thus, marginal and internal adaptation of cobalt-chromium metal copings is considered an essential criterion for assessing clinical quality and success of fixed dental restorations.
Various factors can affect the marginal and internal adaptation of these metal copings, one of them being the finish line preparation. Currently, there is no clear consensus as to which finish line preparation can provide the best marginal and internal adaptation in the case of cobalt-chromium metal copings.
Thus, this scoping review aims to evaluate the effect of different finish line preparations on the marginal and internal adaptation of Cobalt-chromium metal copings fabricated using CAD-CAM technology. This scoping review was conducted as a part of the pilot search for an ensuing systematic review.
METHODOLOGY
The Arksey and O’Malley methodological framework was followed for this scoping review (Figure 1).
Figure 1: Arksey and O’Malley methodological framework for conducting a scoping review
Stage 1: Identifying the research question
The research question defined for this scoping review was, “Do different finish line preparations influence the marginal and internal adaptation of cobalt-chromium metal copings fabricated using CAD-CAM technology?”
The PIO criteria was established based on the research question as follows:
Population: Cobalt-chromium metal copings fabricated using CAD-CAM technology.
Intervention: Different finish line preparations (chamfer, deep chamfer, shoulder, rounded shoulder).
Outcome: Discrepancy in marginal and internal adaptation.
Stage 2: Identifying relevant studies
An electronic search of the PubMed database for articles published from 1st January 2010 to 31st July 2020 was conducted. The search was conducted using a combination of various controlled vocabulary terms (i.e., MeSH terms) as well as free text terms related to the research question. The MeSH terms used were Crown, Computer-Aided Design, Tooth preparation, Prosthodontic and Dental Marginal Adaptation. The free text terms used were cobalt-chromium metal copings, computer-aided designing, computer-aided manufacturing, CAD-CAM, finish line design, chamfer, deep chamfer, shoulder, rounded shoulder, internal fit, internal adaptation, marginal fit and marginal adaptation. Various combinations of the MeSH terms and the free text terms were used to conduct the searches.
Stage 3: Study selection
Articles published from 1st January 2010 to 31st July 2020 were included. Only those studies evaluating effect of different finish line preparations (chamfer, deep chamfer, shoulder, rounded shoulder) on the marginal and/or internal adaptation of single-unit tooth-supported cobalt-chromium metal copings fabricated using CAD-CAM technology were included. Also, articles published in the English language only were included.
Case reports, case series, finite element analysis, review articles and surveys were excluded from this scoping review. Studies evaluating single-unit metal-ceramic restorations after ceramic veneering, multi-unit restorations, all-ceramic restorations, full-metal restorations, implant-supported prosthesis, partial-coverage restorations, or temporary restorations; or cobalt-chromium metal copings fabricated by techniques not involving CAD-CAM technology were also excluded. Studies with sample size less than or equal to 5 were also excluded.
A total of 64 articles were obtained in the searches. 36 articles were excluded after the title and abstract screening, followed by the further exclusion of 19 articles after full text evaluation. 9 articles were eventually identified after applying the inclusion and exclusion criteria and were included in this scoping review (Figure 2).
Stage 4: Charting the data
The data was then extracted from the 9 selected studies and was entered into a Microsoft Excel spreadsheet (Figure 3). The data items that were extracted and charted were:
- Author.
- Year of publication.
- Study setting.
- Sample Size.
- Finish line preparation design.
- CAD-CAM method used for manufacturing the Cobalt-chromium copings.
- Method of measurement of marginal and/or internal fit.
- Marginal and/or internal fit with mean and standard deviation values (in microns).
Figure 2: Flow-chart for the search strategy
Figure 3: Study Characteristics
Stage 5: Collating, summarizing and reporting the results
Out of the 9 articles included, Kim et al., Xu et al., Park et al., Lövgren et al., and Dong-Yeon Kim et al. evaluated the chamfered finish line design. Out of these 5 articles, Kim et al. and Xu et al. used the direct metal laser sintering method for coping fabrication. Park et al. used the hard and soft milling method for coping fabrication whereas Lövgren et al. used the direct metal laser sintering and hard milling method for coping fabrication. Dong-Yeon Kim et al. used the direct metal laser sintering and soft milling method for coping fabrication.
The marginal adaptation with respect to the chamfer finish line preparation seemed to be better when soft milling was used for coping fabrication followed by the direct metal laser sintering. Hard milling methods showed the worst marginal adaptation. No conclusions could be drawn regarding the internal adaptation of the chamfer finish line preparation.
Out of the 9 articles included, only Vojdani et al. evaluated the shoulder finish line preparation. Vojdani Metal. used the hard and soft milling method for coping fabrication and reported a better marginal and internal adaptation with hard milling as compared to soft milling.
Seong-Bin Kim et al. evaluated the deep chamfer finish line and used the hard milling method for coping fabrication, whereas Rödiger et al. evaluated the rounded shoulder finish line and has also used the hard milling method for coping fabrication. No conclusions could be drawn with respect to these two finish lines due to a lack of comparative studies.
Maaz Adel Al et al. evaluated the chamfer, deep chamfer and shoulder finish line preparations and used the direct metal laser sintering method for coping fabrication. They reported a better overall marginal adaptation in deep chamfer finish line preparation followed by shoulder and chamfer finish line preparations. However, they found a better overall internal adaptation in shoulder finish line preparation. This was followed by the chamfer and deep chamfer finish line preparations.
DISCUSSION
Scoping reviews represent an increasingly popular approach to reviewing health research evidence. They present a great tool to help rapidly map the already available literature with respect to a particular subject matter, thereby enabling researchers to identify the research potential and subsequently plan future researches.18,19 Similarly, this scoping review was primarily conducted as a part of a pilot search to assess the range and nature of research available, and to determine the necessity to conduct a systematic review on this topic in the future.
The Arksey and O’Malley methodological framework was followed for this scoping review. This was decided based upon the scoping review conducted by Pham MT et al. in which they found that the Arksey and O'Malley (2005) framework had been used in 62.6% (109/174) of the scoping reviews they evaluated and was thus the most frequently used framework design used for conducting scoping reviews.20 Levac et al. also reported that this framework provided an excellent methodological foundation for conducting scoping reviews.
The advent of CAD-CAM technology has paved the way for a highly precise and efficient digital workflow. The application of this technology for the manufacturing of cobalt-chromium metal copings for fixed dental prosthesis via additive and subtractive manufacturing and the quality of its marginal and internal accuracy has been well documented. However, there remains some amount of uncertainty with respect to the effect of finish line preparations on the marginal and internal adaptation of single-unit tooth-supported cobalt-chromium metal copings fabricated using CAD-CAM technology. Hence, this subject was chosen for defining the research question of this scoping review.
The chamfer, deep chamfer, shoulder and rounded shoulder finish line designs were taken into account since these are the most widely used finish line preparation designs for metal-ceramic fixed dental prosthesis. A PIO format was chosen based on the research question. All the finish line designs were considered in the intervention group, and no comparison group was established to ensure maximum inclusion of data for this scoping review.
As enlisted in the results, a better marginal adaptation was reported in deep chamfer finish line preparation followed by shoulder and chamfer finish line preparations respectively. In contrast, a better internal adaptation was reported in shoulder finish line preparation as compared to chamfer and deep chamfer finish line preparations.
The limitations of this scoping review are that the search was limited to a single database and a select few MeSH terms, and free text terms were used in the search, due to which some of the available literature might have been overlooked.
Despite the limitations, a decent amount of homogenous literature does seem to be available on this subject. This scoping review also found that the effect of different finish line preparations on the marginal and internal adaptation can be due to multiple factors that need to be further elaborated. Thus, a systematic review and meta-analysis needs to be conducted on this subject to come to a more definitive conclusion.
CONCLUSION
- Finish line preparations and the CAD-CAM method of fabrication seem to influence the marginal and internal adaptation of single-unit tooth-supported cobalt-chromium metal copings.
- A better overall marginal adaptation was reported in deep chamfer finish line preparation followed by shoulder and chamfer finish line preparations.
- A better overall internal adaptation was reported in shoulder finish line preparation as compared to chamfer and deep chamfer finish line preparations.
- The marginal adaptation seemed to be better when soft milling was used for coping fabrication followed by the direct metal laser sintering and hard milling methods with respect to the chamfer finish line preparation.
- The marginal and internal adaptation was reportedly better with hard milling as compared to soft milling with respect to the shoulder finish line preparation.
- A more elaborate search of the available literature is required, preferably a systematic review and meta-analysis, to come to a more definitive conclusion regarding the effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal copings fabricated using CAD-CAM technology.
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