PhD Scientific Days 2025

Poster Session III. - S: Dental Research

Cement Spacing as a Compensatory Factor for Intraoral Scan Inaccuracy in Chairside Crown Design: A Virtual Fit Analysis

Előadó neve

Dr. Borbola Dániel József

Neptun code

OVQ7JB

Előadó munkahelye

Semmelweis University Department of Restorative Dentistry and Endodontics

Előadó telefonszáma

0036706124236

Előadó e-mail címe

borbola.daniel.jozsef@semmelweis.hu

Az előadás címe

Cement Spacing as a Compensatory Factor for Intraoral Scan Inaccuracy in Chairside Crown Design: A Virtual Fit Analysis

Szerző(k) neve és munkahelye

Dániel József Borbola¹, János Vág¹

1: Semmelweis University Department of Restorative Dentistry and Endodontics

Bemutatás módja

Poszter

Szekció

Poster Session III. - S: Dental Research

Language of the presentation

English

Preferred session

Dental Research

Összefoglaló szövege

Introduction:
Digital dentistry has transformed restorative workflows with intraoral scanning (IOS) and chairside CAD/CAM systems. Yet, achieving optimal marginal and internal fit remains a challenge. Key factor is the cement spacer setting in CAD software, which determines the virtual relief between the restoration and tooth. While cement spacing helps with seating and fabrication tolerances, the isolated effect of IOS errors—separate from milling artifacts—on fit has not been fully quantified.
Objective:
To evaluate how cement spacer thickness influences IOS-induced inaccuracies in chairside CAD/CAM workflows, using a virtual fit approach that excludes milling variables.
Methods:
Standardized premolar preparations were scanned using the EmeraldS IOS (Planmeca). Crowns were designed in Romexis CAD/CAM software with spacer values from 30 to 140 μm (in 10 μm steps). Each crown was virtually seated onto the original IOS (design stage) and a high-accuracy reference scan (IOS stage). Internal and marginal gaps (MG) were measured to assess the spacer’s compensatory effect.
Results:
A strong linear correlation (pseudo-R² = 0.98) was found between cement spacing and internal gap. At the design stage, regression was y = 6.48 + 0.98x, indicating accurate translation of spacer values. At the IOS stage, y = 12.1 + 0.89x reflected larger mean gaps, suggesting IOS inaccuracy. Internal gap variability (σ) increased significantly with spacing (slope = 0.13, p < 0.001), indicating growing inconsistency between crowns.
MG remained stable (2–17 μm) across spacer values. In the IOS stage, MG followed a non-linear trend: decreasing with spacer values up to ~70 μm, beyond which benefits plateaued. A piecewise regression identified breakpoints between 56–73 μm, indicating that small spacers fail to accommodate scan errors, leading to elevated MGs.
Conclusion:
Cement spacing compensates for IOS-induced errors. Below ~70 μm, marginal gaps increase sharply due to unabsorbed scan distortions. Above this threshold, spacing more effectively accommodates inaccuracies, lowering gaps and variance. However, higher spacing also increases internal gap variability.
Funding:
Project EKÖP-2024-55-VI-4-SE was funded by the Ministry of Culture and Innovation, National Fund for Research, Development and Innovation, under the EKÖP-2024-2025 university grant program.

University

Semmelweis University

Supervisor

János Vág

Publication of my abstract

I do not give consent to the publication of my abstract on the website of the congress.

phd.section.field

in doctoral studies after complex exam (PhD)

Kind

Szabad

Status

elfogadva

Accepted presentation method

poszter

Előadás fájl jóváhagyás

nem rendelkezett róla

Előadó

9033

Start

14:30

End

14:36