18 April 2024

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Chairside VS lab-based methods for single-crown manufacturing: an analysis of accuracy, speed and cost

Lorenzo Breschi

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Digital technology has revolutioned prosthetic dentistry. The advent of intraoral scanners and CAD-CAM softwares has changed the impressions taking and the restorations design with new materials being developed for digital fabrication. Traditionally, prosthetic restorations were fabricated in the laboratory or chairside, but additive manufacturing is becoming increasingly popular among clinicians. Even with the advent of these materials, the marginal accuracy of these restorations is still unknown. Ensuring an accurate fit is critical to avoid problems such as sensitivity or bacterial infiltration. This study aimed to evaluate the accuracy, fit, and cost efficiency of chairside single crowns (SC) compared with traditional methods.

Materials and methods

A plaster model with a prepared tooth (#1.5) was scanned with an industrial scanner, and an SC was designed in computer-assisted-design (CAD) software. SCs (n=10) were printed with a hybrid composite (additive chairside) and a stereolithographic (SLA) printer (Dfab®), 10 SCs were milled in lithium disilicate (subtractive chairside) using a chairside milling unit (inLab MC XL®), and 10 SCs were milled in zirconia (lab-based) using a five-axis laboratory machine (DWX-52D®). All SCs were scanned with the same scanner after polymerization/sinterization. Each scan was superimposed to the marginal area of the original CAD file to evaluate trueness: absolute average (ABS AVG), root mean square (RMS), and (90 ̊–10 ̊)/2 percentile were calculated for each group. Marginal adaptation and quality of the occlusal and interproximal contact points were also investigated by two prosthodontists on 3D printed and plaster models. Finally, the three workflows’ time efficiency and costs were evaluated.

Results

Additive chairside and subtractive lab-based SCs had significantly better marginal trueness than subtractive chairside SCs in all three parameters (ABS AVG, p < 0.01; RMS, p < 0.01; [90 ̊–10 ̊]/2, p < 0.01). However, the two prosthodontists found no significant differences between the three manufacturing procedures in the quality of the marginal closure (p = 0.186), interproximal (p = 0.319), and occlusal contacts (p = 0.218). 

Conclusions

 The three fabricating methods investigated provided highly accurate marginal adaptation. The additive chairside process in particular showed comparable results to traditional subtractive methods, indicating its potential for producing definitive restorations. Both time efficiency and cost trends favored the chairside additive workflow. Nevertheless, further research is needed to confirm these findings and examine the effects of digital fabrication in dentistry.

Mangano FG, Cianci D, Pranno N, Lerner H, Zarone F, Admakin O. Trueness, precision, time-efficiency and cost analysis of chairside additive and subtractive versus lab-based workflows for manufacturing single crowns: An in vitro study. J Dent. 2024 Feb;141:104792. doi: 10.1016/j.jdent.2023.104792. Epub 2023 Nov 25. PMID: 38013004.