Implant crowns.
An implant crown is not a crown on a tooth. There is no periodontal ligament, so the restoration does not depress under load and the patient does not detect overload accurately. Almost every design difference follows from that.
Occlusion designed for the difference
A natural tooth depresses measurably under load through its ligament; an osseointegrated implant barely moves. Loaded together, the teeth give and the implant does not, so the implant takes a disproportionate share.
The conventional response is light contact in maximum intercuspation — enough to hold shimstock under firm closure but noticeably lighter than the adjacent teeth — so that under light function the natural dentition carries the load.
In excursion, keep the restoration free of guiding contact wherever natural teeth can provide it. Lateral load is what implants tolerate least, and a restoration providing canine or group guidance transmits exactly that vector.
Emergence profile
The restoration travels from a round platform at implant level to a tooth-shaped cross-section at the gingival margin, through tissue that responds to whatever shape it is given.
Overcontoured emergence blanches tissue and traps plaque. Undercontoured emergence leaves a space the tissue collapses into and lengthens the clinical crown. Neither is easily corrected once the restoration is definitive.
Where a provisional has already shaped the tissue successfully, record it and send that record — it is the design. See implant provisionals.
Contacts open over time
Interproximal contacts between implant restorations and adjacent natural teeth open over the years. It is well documented, occurs more often on the mesial, and appears to result from continued eruption and mesial drift of the natural dentition against an implant that stays exactly where it was placed.
It cannot be designed out entirely, but a broader contact area takes longer to open into a food trap than a point contact, and a contact positioned more occlusally is less likely to leave a space that packs.
Warn the patient and review it. A contact that has opened and is packing food is manageable; left for years it becomes a caries risk on the adjacent tooth.
Cleansability against aesthetics
A profile that supports the papillae and fills the embrasures looks better and cleans worse. One with open embrasures and generous access cleans well and shows dark triangles.
The balance depends on the patient's hygiene, smile line, dexterity and any history of peri-implant problems. The laboratory cannot judge that from a model.
Say which way you want it resolved. It is a genuine instruction rather than a detail.
Material
Zirconia and lithium disilicate are both used, typically bonded to a titanium base rather than contacting the implant connection directly. Metal-ceramic remains appropriate where strength and a proven track record matter more than the last increment of aesthetics.
Where the restoration will occlude against natural enamel, surface finish matters as much as material — a well-polished surface is considerably kinder to the antagonist than a glazed one.
Reviewing an implant crown over time
Implant restorations need reviewing differently from tooth-borne ones. The patient cannot report overload accurately, there is no ligament to become tender, and the first sign of a problem is frequently radiographic rather than symptomatic.
Check the occlusion at each recall, because it changes as the natural dentition wears and moves while the implant does not. Check the proximal contacts, which open over time. Check the screw is not loose and the tissue is not inflamed.
A restoration that was correct at delivery is not necessarily correct three years later, and adjusting it back into a light contact is straightforward when caught early.
What to send
The implant system, product line, platform diameter and connection type. Intended retention. Stock or custom abutment. The antagonist. Any concern about interocclusal space.
A photograph of the healing abutment in place before removal, showing the tissue contour that has developed, and one of the component packaging. Both take seconds and remove most implant case queries before they arise.
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Send a case
Digital scans and conventional impressions are both accepted. Cases move by UPS and Purolator, and Fairmont works with practices throughout British Columbia and across Canada.