HOME - Clinical cases - Digital Dentistry
03 April 2019

CAD-CAM VS hot-press lithium disilicate crowns: which guarantees a better marginal fit?

Simona Chirico

Increasing demand for esthetic dental restorations has led to the popularity of ceramic restoration systems. Among these the most used is lithium disilicate, which can be produced either in the laboratory with a hot-press technique, or with CAD/CAM system.
The quality of lithium disilicate crowns produced by the CAD/CAM system has always been discussed. From what emerges in literature, there are no differences between the two methods from the structural point of view and the mechanical characteristics. But for clinical success and longevity?
In the study published in The Journal of Prosthetic Dentistry in 2019, Dolev et al. took this aspect into consideration, evaluating the marginal fit by calculating the marginal discrepancy (MD) (the perpendicular measurement from the cervical margin of the casting to the preparation margin) and the absolute marginal discrepancy (AMD) (angular combination of the MD and the extension error - overextension or underextension-) of lithium disilicate crowns produced by the hot-press and CAD-CAM techniques. Acceptable MD values are included between 50 e 120 mm.      

Thirty typodont teeth were divided into 2 groups. Fifteen teeth were scanned with the CEREC Omnicam intraoral scanner, and crowns were fabricated with the CEREC MC XL chairside CAD-CAM milling unit from IPS e.max CAD blocks. Fifteen typodont teeth were sent to a dental laboratory, and lithium disilicate crowns were fabricated from IPS e.max press ingots using the hot-press technique. The 30 crowns were cemented with a self-adhesive cement (RelyX Unicem) and then sectioned with a precision saw. The MD and AMD were measured for each crown with a light microscope.  

 Mean MD and AMD values ​​were evaluated by analyzing 8 specific points of the crowns: disto-buccal (DB), disto-lingual (DL), mesio-buccal (MB), mesio-lingual (ML), mid-buccal location ( Mid-B), mid-lingual location (Mid-L), mid-mesial localtion (Mid-M), mid-distal location (Mid-L).
As expected, the MD values were lower than the AMD values because the AMD is an angular combination of the MD and the extension error. The mean AMD values were lower for the crowns fabricated using the CAD-CAM technique, except at the Mid-L/ML and Mid-D/DL locations.  
The CAD-CAM technique produced an overall mean ±standard error (SE) AMD width of 115 ±4 mm, whereas the hot-press technique produced an overall mean ±SE AMD width of 130 ±5 mm.
The overall mean ±SE MD values were similar: 87 ±3 mm for the crowns fabricated by CAD-CAM and 90 ±4 mm for the crowns fabricated by the hot-press technique.  

Even if the study concludes that there isn’t a statistically significant differences in MD and AMD between the CAD-CAM and hot-press fabrication methods, we can see how the best results are recorded by the lithium disilicate produced with CAD/CAM method.

For additional informations: 
Comparison of marginal fit between CAD-CAM and hot-press lithium disilicate crowns

Related articles

Several prosthodontics rehabilitation processes are needed to recreate a correct masticatory function. The provisional stage is quite important and materials employed in this phase are not completely...

CAD/CAM technology has been used in industry for long time and has increased in popularity over the past years in dentistry from making impressions, casts, provisional and final restorations. The...

Inlay and overlay are a good and right choice in case of large carious and restorative defects. The introduction of CAD/CAM system gives the possibilities to...

Premolars are the most difficult elements to restore and have a high failure rate due to their anatomical position and the forces they undergo. Therefore the choice of the material to restore...

Contemporary computer-aided design and manufacturing (CAD/CAM) systems involve a wide range of dental restoration indications such as inlays, onlays, laminate...

Read more

Bisphosphonates are widely used for the treatment of abnormal bone metabolism for example in osteoporosis. Their continuative use leads to a strong inhibition...

Author: Luigi Campopiano

1. In the light of the fact that the 9 trillion euro of Italian savings are more than 90 % invested in Italy in euros, it is a good idea to expand the scope of investments to other markets that...

Demand of esthetic outcomes is becoming more and more frequent in dentistry and ceramic laminate veneers represent one of the main choices to functionally and...

There is still no accordance on the antibiotic prophylaxis regimen to prevent failures or postoperative infections in healthy patients undergoing standard implant surgery.Some authors proposed...

Editorials     28 July 2020

Welcome Summer 2020

Dear readers, Summer 2020 is definitely a strange and, under certain aspects, never existing season for our planet. The recent notorious burst of...




Most popular