§ 17
Is the connector large enough?
Answer: A bridge most often breaks in the connector between the joints. Each material has a minimum cross-sectional area, e.g. 9 mm² at the front and 12 mm² in the incisor area for a 3-joint bridge in IPS e.max ZirCAD. The connector is almost elliptical, so the area is π/4 × height × width. The calculator shows the area, whether it holds, and how high the connector should be at the width you have space for. Height matters most: strength grows with height squared and stiffness cubed.
Tværsnit (mm²) = π ÷ 4 × højde × bredde (konnektoren regnet som en ellipse)
Højde der kræves = 4 × minimum ÷ (π × bredde)
Strength against bending increases with width × height², stiffness with width × height³ — therefore height matters most
| Symbol | Meaning | Unit |
|---|---|---|
| hoejde_mm | Connector height (occlusal-gingival) | mm |
| bredde_mm | Connector width (buccal-oral) | mm |
| minimum_mm2 | Material's minimum cross-section (from the user manual) | mm² |
| = | Connector cross-section | mm² |
| = | Over (+) or under (−) minimum | mm² |
| = | Height required at this width | mm |
| = | Width required at this height | mm |
Does not apply when
The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.
Substituted
Giver
Members only
Create a free user account to unlock all articles, calculators, templates and range — and get access to quizzes and classes. It takes less than a minute: name, email and a password. No payment card.
Want to try something first? See what you can use without an account — the junior zone, the encyclopedia, the videos and more.
Du bruger den i CAD-designet af en zirkonia- eller keramikbro, når du skal sikre, at konnektorerne er store nok. Producenten har et mindste tværsnit for hvert materiale og område.
En 3-leddet bro fra 5 til 7. Konnektoren er 4,5 mm høj og 3,5 mm bred, og materialet kræver 12 mm².
It means: Tværsnittet er 12.4 mm², altså 0.4 mm² over minimum.
En 3-leddet frontbro har kun plads til en konnektor på 3,5 × 3 mm. Materialet kræver 9 mm².
It means: Tværsnittet er kun 8.2 mm², altså -0.8 mm² i forhold til minimum. Ved samme bredde skal højden være 3.82 mm.
En kindtandskonnektor er 3 mm høj og 4,5 mm bred, og materialet kræver 12 mm².
It means: Tværsnittet er 10.6 mm², altså -1.4 mm² i forhold til minimum. Gør den hellere 3.4 mm høj end 5.09 mm bred, fordi højden giver mest styrke.
En ellipse på 4 × 4 mm er ca. 12,6 mm².
CAD-programmets tværsnitsmåling skal være mindst producentens minimum.