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Preparation design and connector geometry influence the mechanical behavior of additively manufactured periodontal
Ines Bitri1, Karim Nasr1, Frédéric Vaysse2
1Odontology Department, Health Faculty, Toulouse University, 3 Chemin des Maraîchers, Cedex 9, 31062 Toulouse, France.; Odontology Department, Toulouse University Hospital, 3 Chemin des Maraîchers, Cedex 9, 31062 Toulouse, France.
Abstract:
Structural design guidelines for additively manufactured periodontal splints remain poorly defined, particularly regarding relative influence of preparation and connector geometry.
Objective:
This in vitro study evaluated the effect of tooth preparation design and connector cross-sectional geometry on the mechanical behavior of these splints, providing preliminary mechanical insights rather than clinical design recommendations.
Material And Methods:
Standardized specimens were fabricated from a mandibular digital model, combining three preparation designs (no preparation, enamel chamfer finishing line [CFL], and CFL with proximal boxes) with three connector cross-sectional areas (5, 6, and 7 mm²) (n=10 per group; N=90). Specimens were printed by stereolithography using a permanent crown resin and tested under three-point bending (crosshead speed, 1 mm/min). Nominal flexural strength, deformation angle before fracture, and fracture pattern were recorded and analyzed using ANOVA with Bonferroni post hoc tests.
Results:
Preparation design significantly influenced nominal flexural strength (p<.001). CFL alone showed the highest flexural strength (65.79 ± 20.98 MPa), significantly greater than no-preparation (27.36 ± 9.51 MPa) and CFL-with-proximal-boxes (29.64 ± 12.20 MPa). Increasing connector area improved performance only within the CFL group, with no difference between 6 and 7 mm² (73.75 ± 13.82 MPa vs. 81.45 ± 10.04 MPa; p>.99). Deformation capacity followed a similar pattern, and fracture mode was primarily determined by preparation design (p<.0001).
Conclusions:
Preparation design was a stronger determinant of mechanical behavior than connector dimension alone. CFL combined with connector areas ≥6 mm² was associated with improved performance, though these preliminary findings require validation in more clinically representative models.
Clinical Significance:
Tooth preparation design, particularly a limited enamel chamfer finishing line, combined with connector cross-sectional areas ≥6 mm², was associated with improved mechanical performance under the present experimental conditions. These findings provide preliminary structural design insights for additively manufactured periodontal splints and warrant further validation in clinically representative models.
