The height quoted for a Ti-base may describe the bonding wall or the collar below it. Confirm which dimension a paper or catalog uses before comparing designs. A longer collar does not automatically give the crown a taller retentive surface.
For a planned restoration, the useful question is how the selected geometry works with its material and bonding system. For a crown that has already separated, first follow the different problem of Ti-base debonding and identify what actually detached.
Two experiments that resist a universal rule
A 2023 in vitro study compared hybrid-abutment crowns on 4 mm and 7 mm Ti-bases, using three restorative materials and offset implant placement. The authors reported greater retention for the longer bases in their experiment. No specimens failed during the artificial aging phase. Retention was subsequently assessed with a pull-off test.
That sequence matters. The force needed to detach a crown in a testing machine is an endpoint, not an observed number of years in a patient's mouth. The material ranking for retention also cannot establish which crown material is best for every clinical requirement.
In a 2018 laboratory study, 4 mm and 2.5 mm bases were tested with different cements. The reported retention was similar between heights within most cement comparisons, with an exception for one resin cement. Cement selection affected retention. Reading only a general conclusion that height "does not matter" would lose that qualification.
The studies used different combinations and should not be treated as competing votes on one universal minimum. Their results belong to their own specimens and test conditions.
Translate the test before translating the result
Use this comparison sheet when discussing evidence with the laboratory. It is an editorial aid for reading studies, rather than a validated component-selection rule.
| Study field | Corresponding case record |
|---|---|
| Height definition | Bonding wall height distinguished from collar height |
| Base geometry | Exact part, diameter, retentive features and any permitted modification |
| Restoration | Crown material and planned geometry, including any offset |
| Bonding system | Products and applicable instructions for both surfaces |
| Aging and loading | What the experiment simulated and what it omitted |
| Endpoint | Pull-off force, fatigue failure or another clearly named outcome |
Keep the original part drawing beside the completed sheet. If only a nominal height matches, mark the other fields as different or unknown. That prevents a precise-looking dimension from disguising a weak comparison.
A design handoff that identifies the actual base
The laboratory prescription should name the implant connection and the chosen Ti-base, then identify the restorative material and the intended bonding workflow. Ask whether the design requires changing the supplied base. If so, the responsible team should confirm what the manufacturer permits rather than infer permission from a research specimen.
The planned crown also has to fit the available restorative space. Ask the team to explain which constraint led to the selected height and how the alternative would change the design. Do not turn "more retention in a test" into a reason to alter the bite or reduce other materials without reviewing the complete restoration.
Save the decision for future repairs
Retain the final component reference and the laboratory's record of the materials used. If the crown later separates, that information gives the repair team a starting point for investigating the interface. A note containing only "zirconia on titanium" omits the details needed to compare the original work with the proposed repair.
Connection geometry has another dimension: whether the base engages the implant's anti-rotation feature. The guide to engaging and non-engaging Ti-bases covers that separate selection question.
Sources and editorial dates
Sources checked and article first published October 28, 2026. The displayed date, 2026-10-25, is an editorial date assigned within the preceding week. It is not the first publication date. Published cases belong to the cited authors, not this website. The 2023 report was checked in accessible full text. The 2018 experiment is summarized from its abstract. These are laboratory investigations. This educational article and its record aids do not replace an individual clinical assessment.