# Black triangles

From SMILE-FX® · Prepared 31 October 2026

Black triangles are missing gum fill below tooth contacts, even when teeth touch.

A short guide from SMILE-FX® for the conversation with your care team. It cannot assess your mouth or select treatment.

![Author background: greater contact-to-bone distance is linked to less gum fill.](assets/embrasure-anatomy.svg)

Conceptual illustration · unscaled

## Study

A nonrandom, single-centre retrospective cohort: 200 non-extraction adults (third-molar removal allowed), crowding below 5mm, healthy gums or stage-I periodontitis, without prior orthodontics. Central-incisor openings: more frequent and larger with Invisalign® than the cohort’s brackets at removal. Complete-record selection, inflammation timing, missing periodontal covariates and absent long-term recall limit inference, without establishing causation or personal risk.

## Goals

One advanced-periodontal case used artificial restoration. Its abstract cites surgery; the case narrative cites periodontitis. Observation at 18 months is neither a standard schedule nor comparative correction evidence.

### Tissue health

A periodontal clinician treats disease and assesses tooth support. In this case, disease stabilized before restoration; reconstruction was declined.

### Tooth position

An orthodontist moves teeth to change alignment and contacts (authors’ background, untested in this case).

### Visible form

A restorative clinician shapes artificial material to replace missing visible form; this does not regrow living gum.

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## Sources

- [2023 cohort](https://head-face-med.biomedcentral.com/articles/10.1186/s13005-023-00375-0)
- [2013 case](https://pmc.ncbi.nlm.nih.gov/articles/PMC3723290/)

No cited researcher reviewed or endorsed this guide.

## Contact

Already in treatment? Follow your treating team's directions and contact them about your care.

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