04 February 2022

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Is there a correlation between the scanners accuracy and pulp chamber depth of endocrowns?

Simona Chirico

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The restoration of endodontically treated teeth is always a current challenge in the dental field. A valid type of restoration is the use of endocrown, a monoblock restoration that exploits the retention inside the pulp chamber to give resistance to the dental element. This type of restoration is closely related to CAD / CAM technology. Today there are many scanners on the market and they show excellent performance not only in taking an impression of a single tooth, but also in full arches. The performance of intraoral scanners depends on the accuracy and precision they have in recording the impressions. The success of the endocrown, however, depends not only on the marginal adaptation between the restoration and the tooth, and the pulp chamber depth, but also on the accuracy of the scanner. 

What is the correlation between these two aspects? The answer is given in the article by Gurpinar et al, published in The Journal of Prosthetic dentistry

Material and methods. 
Six different IOSs were compared: TRIOS 3, CEREC Omnicam, CEREC Primescan, Planmeca Emerald, iTero Element2, and Virtuo Vivo. Endocrown preparations were digitally designed with a computer-aided design and computer-aided manufacturing (CAD-CAM) software program (Rhicoceros), and the PCEDs of preparations were 2, 3.5, and 5 mm. Designed preparations were milled from a polymethylmethacrylate block (Telio CAD) with a milling unit. Reference scans were obtained from an industrial scanner (ATOS), and 5 test scans of each cavity were made with 6 IOSs. All scans were converted into standard tessellation language (STL) files. The data sets obtained from the IOSs were superimposed on the reference scan to evaluate trueness and on each other within groups to determine precision by using a 3D analysis software program (Geomagic Control X). Obtained data were analyzed with 1-way ANOVA and Tukey HSD tests (a=.05). 

Results
CEREC Primescan was found to have the best trueness and precision among the evaluated IOSs (P<.05), while Planmeca Emerald was found to have the lowest trueness (P<.05). For all tested PCEDs, statistically significant differences were found among IOSs. A PCED with a 2-mm depth (18.57 ±4.80 mm) showed significantly better scanning trueness than that with a 5-mm depth (23.81 ±6.53), while no significant differences were found between 2 and 3.5 mm (P>.05). 

Conclusions
Deep pulpal chamber extensions of endocrown restorations could negatively affect scanning accuracy, and scanning accuracy varies depending on the selected IOS. CEREC Primescan appears to be the best IOS choice for scanning endocrowns with deep pulpal chamber extensions. 

For additional information: Effect of pulp chamber depth on the accuracy of endocrown scans made with different intraoral scanners versus an industrial scanner: An in vitro study