It is easy to assume you can tell whether someone has thin or thick gums just by looking. Research says otherwise. When clinicians judged the gum type of healthy people from clinical slides alone, they identified it correctly in only about half of cases, whatever their experience, and nearly half of the thin, scalloped cases were misclassified. That matters for smile design, because gum thickness may affect how the gum line behaves around veneers, crowns, implants and teeth being moved with braces or aligners.
This article explains what gum phenotype means, how it is measured, what thin gums are linked with in the research, and how a dentist may take it into account when planning cosmetic work.
Phenotype describes how thick and wide the gum is
Older articles use the word biotype. The 2017 World Workshop on the classification of periodontal (gum) and peri-implant diseases and conditions recognised the importance of the gingival phenotype, which takes in how thick the gum is and how wide the band of firm (keratinised) gum is around each tooth. Reviews since then also include the shape of the bone underneath (the bone morphotype) when describing the overall periodontal phenotype.
A 2014 systematic review in the Journal of Clinical Periodontology found that published definitions were unclear and sometimes inconsistent, but that three broad groups were a reasonable way to describe people: thin and scalloped, thick and flat, and thick and scalloped. Scalloped means the gum line rises in a high arch over each tooth. The review found only weak to moderate links between tooth shape, gum shape and bone shape. The only consistent positive links were between gum thickness, the width of firm gum and the bone shape.
Tooth shape is not a reliable guide
A common teaching is that long, narrow front teeth come with thin, scalloped gums and short, square teeth come with thick, flat gums. The evidence is mixed.
In a study from Belgium of 100 people with healthy gums (De Rouck and colleagues, 2009), about one third had clearly thin gums, mostly women with slender teeth and a high scalloped gum line. About two thirds had thick gums, mostly men. Only about half of the thick group had the square teeth and flat gum line the textbook pattern predicts. The other half had thick gums with slender teeth and a high scallop.
A German study of 80 young adults (Fischer and colleagues, 2014) found no link between gum thickness and the width-to-length ratio of the tooth crowns, and the authors suggested the traditional idea may be questionable.
Thickness also changes around the mouth. A 2024 systematic review of 17 studies, covering 3,277 adults in 11 countries, found that thickness differed from tooth to tooth: the upper central incisors and the first molars were more often thick, while the premolars were more often thin. The authors advised assessing each tooth that needs treatment rather than judging from the overall look of the smile. An American Academy of Periodontology review (Kim and colleagues, 2020) also found that phenotype varies between people and between areas of the same mouth, and that people of Asian background tended to have thinner gums than white people in the studies it included.
How gum thickness is measured
Three approaches appear in the research. Each has limits, which is one reason the result is best treated as one piece of information rather than a label.
| Method | How it works | What studies found |
|---|---|---|
| Looking | The clinician judges the gum by eye or from photos | Correct in about half of cases when judged from clinical slides, and nearly half of thin, scalloped cases were misclassified (Eghbali and colleagues, 2009) |
| Probe test | A thin measuring probe is placed gently in the gum crevice. If its outline shows through the gum, the gum is classed as thin | In one study of 48 patients, results did not differ significantly from direct measurement, while looking alone did (Kan and colleagues, 2010). A 2026 meta-analysis of 10 studies found the test could lead to inaccurate results, especially for thin gums: summary sensitivity was only about 50%, and accuracy depended on the cut-off used and where the thickness was measured |
| Direct measurement | The thickness is measured in millimetres, for example with a calliper after an extraction | Used as the reference in research. In the 2010 study, gum of 1 mm or less was classed as thin |
What thin gums are linked with
Gum recession
The 2020 American Academy of Periodontology review found that gum recession was more common and more severe at sites with thin gum than at sites with thicker gum. A 2018 review prepared for the World Workshop (Cortellini and Bissada) reached a similar conclusion, and added that poor cleaning, orthodontic treatment and fillings or crowns near the gum line may also raise the risk. An older study from Sweden (Olsson and Lindhe, 1991) found that people with long, narrow upper central incisors had more recession on the outer surfaces of their teeth than people with short, wide ones. Our article on gum recession covers the other causes.
Moving teeth with braces or aligners
A 2023 systematic review in the European Journal of Orthodontics found that tipping the front teeth forward during orthodontic treatment was linked with more recession in 10 of 16 studies. Thin gums, existing recession, the width of firm gum and the thickness of the gum at the margin were linked with a higher risk of recession after treatment in nine studies. The studies varied a lot in design, so the authors were cautious. Our article on whether clear aligners can cause gum recession explains what to watch for during treatment.
Colour showing through around implants
The two studies described here used pig tissue in the laboratory (in vitro), so they show principles rather than what will happen in a particular mouth. In a study using pig jaws (Jung and colleagues, 2007), titanium, zirconia and porcelain-covered versions of both all changed the colour of the overlying tissue, and the change became smaller as the tissue got thicker. Titanium caused the most change. Zirconia caused no visible change under 2 mm or 3 mm of tissue, and at 3 mm the eye could not see a difference with any of the materials tested. A later study by the same Zurich group (Ioannidis and colleagues, 2017) found discolouration with every material tested and confirmed that it tended to decrease as the tissue got thicker. This is part of why the tissue over a front implant is assessed carefully, as described in our article on a front tooth implant.
How it may change a smile plan
Knowing that the gum around a tooth is thin does not decide the treatment, but it can shape the details. Where the edge of a veneer or crown sits in relation to the gum, which material is chosen near the gum line, and how far front teeth are moved during orthodontic treatment are all choices a dentist may weigh differently for thin gum. It is also useful context when planning the position of the gum line itself, which our article on the gingival zenith explains. If an older crown already shows a grey edge at the gum, our article on a dark line at the gum around a crown covers the usual causes.
Thin gum on its own does not usually need treatment. The 2018 review advised that in the absence of problems, monitoring is usually the appropriate approach, and the 2020 Kim review found no published evidence that thickening thin gum helps where there is no recession or other defect. Around implants, a second 2020 review (Lin and colleagues) found that surgically thickening the tissue may reduce later recession of the gum around the implant, but it found no controlled studies for crowns or bridges on natural teeth. Where gum surgery is being considered, referral to a periodontist may be part of the discussion.
For dentists: the probe test as a quick chairside screen
Placing a periodontal probe gently in the mid-facial sulcus and checking whether its outline shows through the gingiva takes seconds and needs no extra equipment. The research supports using it as a quick indicator, with some limits worth keeping in mind:
- It is repeatable. In the De Rouck study, the same examiner repeated the probe test with 85% agreement (kappa 0.70).
- It beats looking alone. In the Kan study, probe results did not differ significantly from direct measurement after extraction, while visual assessment did.
- It still misses thin tissue. The 2026 meta-analysis found summary sensitivity of only about 50% for picking up a thin phenotype, so a probe that stays hidden does not rule thin gingiva out.
- The probe changes the answer. A 2025 study in the Journal of Periodontology (Uysal and colleagues) had four assessors judge photographs of a standard probe and of colour-coded and metal phenotype probes in the sulcus. Agreement between assessors varied with probe type and tip colour, no gingival thickness cut-off reliably separated thin from non-thin, and the authors concluded the method has a high potential to misclassify whichever probe is used. At lower incisors, a 2024 study of 200 people found a standard probe and a colour-coded probe set agreed in about 71% to 74% of cases, although the kappa values were low (0.20 and 0.31) and the authors described the association as weak.
In practice, that makes the probe test a useful first screen rather than a final answer. Use the same probe each time, record the result per tooth rather than per patient, and where a decision depends heavily on tissue thickness, such as moving thin-tissued incisors forward or placing an implant in the front of the mouth, a more direct assessment may be worth considering, such as transgingival probing, which the 2025 study used to measure actual gingival thickness.
Questions people ask about gum thickness
Can I tell if my gums are thin by looking in the mirror?
Not reliably. Clinicians judging from clinical photos were correct only about half the time, so a mirror check is not a reliable guide. A dentist or OHT can check in the chair.
Does thin gum mean I cannot have veneers?
Not necessarily. It is one of several factors in planning, along with the bite, the existing gum line and the health of the gums. A dentist can explain how it affects your options at a consultation.
Planning a smile with the gums in mind
Lumi Dental has a clinical photography room for smile planning. If you are thinking about porcelain veneers, crowns on front teeth or orthodontic treatment, you can book a free cosmetic consult at our Melrose Park practice to talk through how your gums may affect the plan.
Sources
- Jepsen S and colleagues. Periodontal manifestations of systemic diseases and developmental and acquired conditions: consensus report of workgroup 3 of the 2017 World Workshop. Journal of Periodontology, 2018. PubMed 29926943
- Cortellini P, Bissada NF. Mucogingival conditions in the natural dentition: narrative review, case definitions, and diagnostic considerations. Journal of Periodontology, 2018. PubMed 29926948
- Zweers J and colleagues. Characteristics of periodontal biotype, its dimensions, associations and prevalence: a systematic review. Journal of Clinical Periodontology, 2014. PubMed 24836578
- De Rouck T and colleagues. The gingival biotype revisited: transparency of the periodontal probe through the gingival margin as a method to discriminate thin from thick gingiva. Journal of Clinical Periodontology, 2009. PubMed 19419444
- Fischer KR and colleagues. On the relationship between gingival biotypes and supracrestal gingival height, crown form and papilla height. Clinical Oral Implants Research, 2014. PubMed 23718206
- Dridi SM and colleagues. Prevalence of the gingival phenotype in adults and associated risk factors: a systematic review of the literature. Clinics and Practice, 2024. PubMed 38804396
- Kim DM, Bassir SH, Nguyen TT. Effect of gingival phenotype on the maintenance of periodontal health: an American Academy of Periodontology best evidence review. Journal of Periodontology, 2020. PubMed 31691970
- Eghbali A and colleagues. The gingival biotype assessed by experienced and inexperienced clinicians. Journal of Clinical Periodontology, 2009. PubMed 19811580
- Kan JY and colleagues. Gingival biotype assessment in the esthetic zone: visual versus direct measurement. International Journal of Periodontics and Restorative Dentistry, 2010. PubMed 20386780
- Moreira Rodrigues D and colleagues. Diagnostic accuracy of the gingival phenotype by the transparency of the periodontal probe through the gingival sulcus: a systematic review and meta-analysis. International Journal of Periodontics and Restorative Dentistry, 2026. PubMed 39270331
- Uysal BF, Köse T, Gürkan A. Gingival phenotype classification by visual and probe visibility assessments: relationship with thickness and probe design. Journal of Periodontology, 2025. PubMed 39119887
- Kloukos D and colleagues. Assessment of gingival translucency at the mandibular incisors with two different probing systems: a cross sectional study. Clinical Oral Investigations, 2024. PubMed 38942966
- Olsson M, Lindhe J. Periodontal characteristics in individuals with varying form of the upper central incisors. Journal of Clinical Periodontology, 1991. PubMed 2045523
- Cadenas de Llano-Pérula M and colleagues. Risk factors for gingival recessions after orthodontic treatment: a systematic review. European Journal of Orthodontics, 2023. PubMed 37432131
- Jung RE and colleagues. In vitro color changes of soft tissues caused by restorative materials. International Journal of Periodontics and Restorative Dentistry, 2007. PubMed 17694948
- Ioannidis A and colleagues. Discoloration of the mucosa caused by different restorative materials: a spectrophotometric in vitro study. Clinical Oral Implants Research, 2017. PubMed 27452796
- Lin GH and colleagues. The significance of surgically modifying soft tissue phenotype around fixed dental prostheses: an American Academy of Periodontology best evidence review. Journal of Periodontology, 2020. PubMed 31670835
This article is general information only and is not a substitute for an in-person assessment by a dental professional.
