Evaluation of marginal discrepancy in metal frameworks fabricated by sintering-based computer-aided manufacturing...

Area of Science:

• Dental materials science and engineering
• Biomaterials and biomedical engineering
• Digital dentistry and prosthodontics

Background:

• Computer-aided design and computer-aided manufacturing (CAD/CAM) technologies have revolutionized dental prosthodontics.
• Sintering-based CAD/CAM techniques are increasingly used for fabricating metal frameworks for fixed partial dentures.
• Optimizing fabrication processes is crucial for achieving precise marginal fit, a key factor for prosthesis longevity and patient comfort.

Purpose of the Study:

• To investigate the impact of different sintering procedures on the marginal discrepancies of metal frameworks produced via CAD/CAM.
• To compare the marginal accuracy of frameworks fabricated using hard milling, soft milling, and direct metal laser melting (DMLM) with varying layer thicknesses.

Main Methods:

• Forty resin die models of prepared teeth were used to fabricate metal frameworks by four methods: hard milling (HM), soft metal milling (SM), DMLM with 25 µm layer thickness (L25), and DMLM with 50 µm layer thickness (L50).
• Marginal discrepancies were measured vertically at four axial sites (buccal, pontic-facing, lingual, away-from-pontic) under a stereomicroscope after framework cementation.
• Statistical analysis was performed with a significance level of 0.05.

Main Results:

• No significant differences in marginal discrepancy were observed among the four axial sites within each fabrication method.
• The hard milling (HM) and 25 µm DMLM (L25) groups exhibited significantly lower marginal discrepancy values compared to the soft milling (SM) and 50 µm DMLM (L50) groups (P<.001).

Conclusions:

• The sintering procedure type did not influence marginal discrepancy at sites facing the pontic.
• All evaluated CAD/CAM fabrication methods produced metal frameworks with clinically acceptable marginal discrepancies.