Osseo IQ
Chapter 4 · Surgical · §4.6

Peri-implant Soft-Tissue Grafting: Widen, Thicken, or Leave It

Matching the soft-tissue deficiency to the right graft — and knowing when no graft is the correct answer.

Compiled by
Tan Khuu, DDS
Licensed dentist (CA & SC)
Audience
Oral surgeons, prosthodontists, periodontists & residents
Edition
1.0 · June 2026
Reviewed
June 2026 · next review June 2027
Reading time
~16 minutes
Evidence basis
Consensus statements + systematic reviews + primary literature
§4.6.1 — Overview

Matching the deficiency to the graft

Soft-tissue grafting around implants is not a single procedure with a single indication; it is a small family of operations, each answering a different anatomical question. The clinician's first task is therefore diagnostic rather than surgical — to decide which dimension of the peri-implant phenotype is deficient before deciding what to do about it. Three dimensions matter: the width of keratinized mucosa, the thickness of the mucosa (its biotype), and the depth of the vestibule. Each maps to a characteristic graft, and confusing one deficiency for another is the most common way a technically clean operation fails to solve the patient's problem.2

Two working thresholds organize the whole field. A band of keratinized mucosa narrower than 2 mm is conventionally regarded as deficient; narrow keratinized tissue is associated with more plaque accumulation, more peri-implant inflammation, and more patient-reported brushing discomfort, and the soft-tissue augmentation that addresses it improves these inflammatory parameters relative to non-augmented sites.13 More recent meta-analytic data, however, suggest the predictive value of the width threshold for frank peri-implant disease is modest, particularly in compliant patients.4 A mucosal thickness below 2 mm defines a thin phenotype, at risk of greyish titanium "shine-through," recession, and — in some data — greater early marginal bone loss.2 The mnemonic that follows from this is simple: free gingival grafting widens keratinized tissue; connective-tissue (subepithelial) grafting thickens it and covers recession.

The distinction is not arbitrary; it follows the biology of the donor tissue. A free gingival graft (FGG) carries its own keratinizing epithelium and lamina propria, so it transplants the genetic instruction to keratinize and reliably establishes a band of attached, keratinized mucosa. A connective-tissue graft (CTG) is de-epithelialized; it adds volume and vascular connective tissue beneath a flap, thickening the phenotype and, under a coronally advanced or tunnel approach, covering an exposed surface — but it does not, on its own, generate a wide keratinized band. Where donor morbidity is a concern, a xenogeneic collagen matrix is a reasonable substitute for either, though the autogenous graft remains superior for the specific outcome it is chosen to achieve.1

Timing is the third axis of the decision. Augmentation may be performed before implant placement, at placement, or after — most often at second-stage (uncovery) surgery or in the pre-prosthetic phase. Thickness gain and recession coverage are frequently carried out at placement or second stage; keratinized-width gain and vestibuloplasty are typically staged at second stage or pre-prosthetically, allowing the graft to mature before the prosthesis is delivered.2

The first decision in soft-tissue grafting is not surgical but diagnostic: which dimension of the phenotype is missing?
◆ Key concept · The two 2-mm thresholds

Keratinized mucosa width < 2 mm is the working threshold for a width deficiency — the FGG question. Mucosal thickness < 2 mm is the working threshold for a thickness/biotype deficiency — the CTG question. The two are independent: a site can have a wide keratinized band that is paper-thin, or a thick mucosa that is barely keratinized. Diagnose each dimension separately, because each is treated by a different graft. Both values are pragmatic guides, not absolute cut-offs.

§4.6.2 — Phenotype assessment

The three soft-tissue dimensions

Before any incision, characterize the peri-implant phenotype along its three dimensions. A minimum of roughly 2 mm of keratinized tissue and roughly 2 mm of thickness supports the biological seal, hygiene access, and esthetics; a deficiency in either, or a shallow vestibule that traps plaque, defines the surgical target.3

Keratinized mucosa width

The band of firm, attached keratinized mucosa resists the frictional and inflammatory insults of mastication and brushing. A width below 2 mm is deficient on the working threshold; narrow keratinized tissue correlates with more plaque, more inflammation, and more discomfort, and is most often a problem in the posterior mandible, where mobile alveolar mucosa and muscle pull encroach on the implant. This deficiency is addressed primarily by the free gingival graft.3

Mucosal thickness / biotype

Thickness is independent of width. A mucosa thinner than 2 mm is a thin phenotype, prone to grey titanium shine-through, to recession and soft-tissue dehiscence, and — in some studies — to greater early marginal bone loss. The deficiency is addressed by the connective-tissue (subepithelial) graft, which adds vascular volume beneath the flap.2

Vestibular depth

A shallow vestibule traps plaque and physically limits the patient's brushing access; it frequently co-exists with a narrow keratinized band. Deepening it with an FGG combined with an apically positioned flap and vestibuloplasty both gains keratinized tissue and improves hygiene access and comfort.

§4.6.3 — Decision pathway

From dominant deficiency to graft

The figure below contrasts the two principal autogenous grafts by what they deliver: the FGG re-establishes a keratinized band by transplanting keratinizing epithelium, while the CTG adds sub-flap volume to thicken the phenotype and cover recession. Read it as the visual form of the FGG-widens / CTG-thickens rule.

Free gingival graft → WIDTH alveolar bone < 2 mm before wide keratinized band gained Connective-tissue graft → THICKNESS alveolar bone < 2 mm volume added beneath flap thicker, recession-resistant phenotype
Figure 1. The two principal autogenous grafts answer different questions. The free gingival graft (left) transplants keratinizing epithelium to widen the keratinized band — the < 2 mm width deficiency. The connective-tissue graft (right) adds sub-flap volume to thicken a < 2 mm phenotype and resist recession. Schematic; not to scale.12

Interactive grafting selector

Identify the dominant deficiency, then match it to the graft that addresses it. Some sites need both width and thickness — sequence or combine accordingly. Tap a deficiency to expand the recommended pathway.

Tap the deficiency that best describes the site.

§4.6.4 — Quick reference

Indication → graft type → timing

The table consolidates the decision. Each row pairs a deficiency with the graft that addresses it and the window in which it is conventionally performed, with the strength of the supporting evidence noted alongside.

Table 1 · Deficiency, graft selection, and timing
IndicationGraft typeTimingEvidence
Increase KT width (< 2 mm)Free gingival graft (FGG); xenogeneic collagen matrix as alternative2nd stage or pre-prostheticSyst. review
Increase thickness (thin phenotype, < 2 mm)Connective-tissue / subepithelial graft (CTG); collagen matrix as alternativeAt placement or 2nd stageSyst. review
Cover recession / dehiscenceCTG (± coronally advanced or tunnel flap)After diagnosis; phenotype-dependentSyst. review
Deepen vestibuleFGG / apically positioned flap + vestibuloplastyPre-prostheticConsensus
Adequate phenotype (KT ≥ 2 mm, thick)No graft — maintenance & monitoringRoutine recallConsensus
✦ Clinical pearl · Choose the graft by the outcome, not by habit

If the goal is a wider keratinized band, only a graft carrying keratinizing epithelium — the FGG — reliably delivers it; a CTG buried under a flap will thicken but not widen. If the goal is thickness or coverage, the CTG out-performs collagen-matrix substitutes for soft-tissue thickness gain. Name the outcome first, then the graft follows.1

▲ Common pitfall · Treating the wrong dimension

The classic error is placing a connective-tissue graft to "fix" a keratinized-width problem, then finding the mobile mucosa and brushing discomfort unchanged because no keratinized band was created. The mirror error is harvesting an FGG for an esthetic anterior thin-phenotype case, leaving a pale, poorly color-matched patch where a buried CTG would have thickened the tissue invisibly. Diagnose width and thickness as separate problems before selecting the donor tissue.

§4.6.5 — Glossary

Key terms

Keratinized mucosa width (KT / KM)
The apico-coronal dimension of firm, attached, keratinized peri-implant mucosa; a width < 2 mm is the working threshold for deficiency.
Mucosal thickness / biotype
The bucco-lingual thickness of the peri-implant mucosa; < 2 mm defines a thin phenotype prone to shine-through and recession.
Free gingival graft (FGG)
An epithelialized graft (usually palatal) that transplants keratinizing epithelium to widen the band of keratinized mucosa and deepen the vestibule.
Connective-tissue / subepithelial graft (CTG)
A de-epithelialized graft placed beneath a flap to add volume — thickening the phenotype and covering recession or dehiscence.
Xenogeneic collagen matrix
A non-autogenous substitute that avoids a second surgical site; an alternative to FGG or CTG but inferior for the specific autogenous outcomes.
Coronally advanced flap (CAF)
A flap mobilized and repositioned coronally, commonly combined with a CTG to cover an exposed surface.
Vestibuloplasty
A procedure that deepens the vestibule, often with an apically positioned flap and FGG, to improve hygiene access.
Shine-through
The greyish discoloration of thin mucosa caused by the underlying titanium or restorative material showing through.
§4.6.S — Self-test

Board preparation

1. The conventional working threshold below which keratinized mucosa width is considered deficient is:
B is correct. A keratinized band < 2 mm is the pragmatic threshold for deficiency, associated with more plaque, inflammation, and brushing discomfort.
2. A posterior mandibular implant has 1 mm of keratinized mucosa and a shallow vestibule. The most appropriate graft to widen the keratinized band is:
A is correct. The FGG transplants keratinizing epithelium and reliably widens the keratinized band; combined with an apically positioned flap it also deepens the vestibule.
3. The working threshold below which mucosal thickness defines a thin phenotype is:
C is correct. A thickness < 2 mm is the working threshold for a thin phenotype, risking shine-through and recession; a thickness ≥ 2 mm helps avoid an unfavorable shine-through effect.
4. A thin-phenotype esthetic anterior implant with greyish shine-through is best managed by:
B is correct. The CTG thickens the phenotype invisibly beneath the flap, masking shine-through, whereas an FGG would leave a pale, poorly color-matched patch in the esthetic zone.
5. The consensus framework underlying these thresholds and recommendations derives chiefly from:
B is correct. The framework draws on the Osteology Foundation consensus report (Giannobile, Jung & Schwarz 2018) and associated systematic reviews (Thoma 2018; Lin, Chan & Wang 2013).
6. Soft-tissue augmentation to gain keratinized tissue has been shown to:
B is correct. The Thoma 2018 systematic review found augmentation for keratinized-tissue gain improved gingival and plaque indices and yielded more stable marginal bone than non-augmented sites.
7. When donor-site morbidity is a concern and an autogenous graft is to be avoided, a reasonable substitute is:
B is correct. A xenogeneic collagen matrix avoids a second surgical site and is an accepted alternative to FGG or CTG, though autogenous grafts remain superior for their specific outcomes.
8. For increasing soft-tissue thickness, the connective-tissue graft compared with volume-stable collagen matrices generally performs:
C is correct. The CTG out-performs collagen-matrix substitutes for soft-tissue thickness gain; the matrix is chosen mainly to reduce a second surgical site, not for superior thickness.
9. Keratinized-width deficiency is most commonly encountered at which site?
B is correct. The posterior mandible, with its mobile alveolar mucosa and muscle pull, is the classic site for narrow keratinized tissue.
10. To cover an exposed implant surface (soft-tissue dehiscence) in an adequately keratinized but thin site, the preferred approach is:
B is correct. A CTG combined with a coronally advanced or tunnel flap thickens the tissue and covers the exposed surface; an FGG would not provide coverage or color match.
11. A site with KT ≥ 2 mm, thick stable tissue, and no esthetic or hygiene concern should be managed by:
C is correct. With an adequate phenotype, grafting is not indicated; document the baseline, reinforce hygiene, and monitor, intervening only if the phenotype deteriorates.
12. Keratinized-width augmentation (FGG) is conventionally timed:
B is correct. FGG for width gain is typically staged at second stage or pre-prosthetically, with maturation permitted before the prosthesis is delivered.
13. Increasing soft-tissue thickness with a CTG is most commonly performed:
B is correct. Thickness gain with a CTG is frequently carried out at placement or second stage, integrating augmentation with the surgical timeline.
14. The principal biological reason an FGG, not a CTG, is chosen to widen keratinized tissue is that the FGG:
B is correct. The FGG carries its own keratinizing epithelium, so it establishes a keratinized band; a de-epithelialized CTG adds volume but does not generate keratinized width.
15. A shallow vestibule around an implant most directly causes:
B is correct. A shallow vestibule traps plaque and physically limits hygiene access; it often co-exists with a narrow keratinized band and is treated with FGG/vestibuloplasty.
16. A thin peri-implant phenotype has been associated in some studies with:
B is correct. Thin tissue risks grey shine-through and recession and, in some data, tracks greater early marginal bone loss — a rationale for thickening.
17. A site has a wide keratinized band but is paper-thin with shine-through. The correct interpretation is:
B is correct. The two dimensions are independent. A wide but thin band is a thickness/biotype problem, addressed by a CTG, not an FGG.
18. The 2 mm values for keratinized width and mucosal thickness are best described as:
B is correct. The thresholds are pragmatic guides; graft selection and timing remain case-specific, and some data show the width threshold's predictive value is modest.
19. A site needs both a wider keratinized band and a thicker phenotype. The appropriate strategy is to:
B is correct. Sites deficient in both dimensions are managed by sequencing or combining width (FGG) and thickness (CTG) augmentation as the case requires.
20. The single most important first step before selecting any soft-tissue graft is to:
A is correct. The first task is diagnostic: identify the deficient dimension, because each maps to a different graft. Selecting a procedure before diagnosing the deficiency is the root of most failed grafting.
1. A patient has a posterior mandibular implant with 1 mm of keratinized mucosa, a shallow vestibule, and brushing discomfort. Walk me through your assessment and plan.
Model answer. I assess the three soft-tissue dimensions: keratinized width, thickness, and vestibular depth. Here the dominant deficiency is keratinized width < 2 mm, compounded by a shallow vestibule — a width-and-access problem, not a thickness problem. The correct graft is a free gingival graft from the palate, which transplants keratinizing epithelium to establish an attached keratinized band, combined with an apically positioned flap and vestibuloplasty to deepen the vestibule and improve hygiene access. I stage this at second-stage surgery or pre-prosthetically and allow the graft to mature before loading. If thickness were also deficient, I would plan to address the phenotype as well.
Examiner follow-ups:
  • Why not a connective-tissue graft here?
  • What evidence supports widening keratinized tissue in this setting?
  • How would your timing change if the vestibule were adequate?
2. Contrast the free gingival graft and the connective-tissue graft — what each delivers and why you would choose one over the other.
Model answer. The FGG is an epithelialized graft that carries keratinizing epithelium; it transplants the instruction to keratinize and reliably widens the keratinized band, and it deepens the vestibule when combined with an apically positioned flap. The CTG is de-epithelialized and placed beneath a flap; it adds vascular volume to thicken the phenotype and, under a coronally advanced or tunnel approach, covers recession or dehiscence. I choose the FGG when the deficiency is keratinized width, and the CTG when the deficiency is thickness or when I need coverage and color match in the esthetic zone. Naming the outcome first — width versus thickness/coverage — dictates the graft.
Examiner follow-ups:
  • When is a collagen matrix an acceptable substitute, and what is the trade-off?
  • Why does a buried CTG fail to widen keratinized tissue?
3. Justify the 2 mm thresholds for keratinized width and mucosal thickness, and tell me how rigidly you apply them.
Model answer. A keratinized band < 2 mm is associated with more plaque, inflammation, and brushing discomfort, and augmentation to gain keratinized tissue improves inflammatory parameters and stabilizes marginal bone relative to non-augmented sites — the basis of the width threshold. A mucosal thickness < 2 mm risks shine-through and recession and, in some studies, greater early bone loss — the basis of the thickness threshold. I treat both as pragmatic working values, not absolute cut-offs: I weigh symptoms, site, esthetic demand, and patient compliance. Indeed, more recent meta-analyses show the keratinized-width threshold has only modest predictive value, especially in compliant patients, so I individualize rather than operate on a number alone.
Examiner follow-ups:
  • Which consensus and systematic reviews support these values?
  • How does patient compliance change your threshold for surgery?
4. Take me through how timing of soft-tissue augmentation is decided across the implant treatment sequence.
Model answer. Augmentation can be performed before placement, at placement, or after — most often at second-stage surgery or in the pre-prosthetic phase. Thickness gain with a CTG and recession coverage are commonly done at placement or second stage, integrating with the surgical timeline so the soft tissue is optimized before the prosthesis. Keratinized-width gain with an FGG and vestibuloplasty are typically staged at second stage or pre-prosthetically, because the graft must mature into an attached band before loading. The governing principle is to have the desired phenotype established and matured before the definitive restoration is delivered, since correcting soft tissue after a prosthesis is in place is harder and less predictable.
Examiner follow-ups:
  • Why prefer second stage for width gain rather than at placement?
  • What is the risk of delaying augmentation until after loading?
5. A site has a wide keratinized band but is thin with grey shine-through in the esthetic zone. Defend your management and explain the common error you are avoiding.
Model answer. Width and thickness are independent dimensions. This site has adequate keratinized width but a thickness deficiency < 2 mm with shine-through, so the indicated graft is a connective-tissue (subepithelial) graft placed beneath the flap to thicken the phenotype invisibly and mask the grey show-through; a tunnel or coronally advanced approach preserves the papillae and color match. The error I am avoiding is harvesting a free gingival graft because the tissue "needs grafting" — an FGG would widen what is already adequate and leave a pale, poorly matched epithelial patch in the esthetic zone, worsening the very problem I was asked to treat. Diagnosing the deficient dimension before selecting the donor tissue is what prevents that mistake.
Examiner follow-ups:
  • Why does the CTG outperform a collagen matrix for thickness here?
  • How would you stage this relative to the definitive crown?
  • What would change your plan if the band were also narrow?
§4.6 — References

References

  1. Thoma DS, Naenni N, Figuero E, et al. Effects of soft tissue augmentation procedures on peri-implant health or disease: a systematic review and meta-analysis. Clin Oral Implants Res. 2018;29(Suppl 15):32–49. doi:10.1111/clr.13114 Syst. review
  2. Giannobile WV, Jung RE, Schwarz F; Workshop Group 1. Evidence-based knowledge on the aesthetics and maintenance of peri-implant soft tissues: Osteology Foundation Consensus Report Part 1 — Effects of soft tissue augmentation procedures on the maintenance of peri-implant soft tissue health. Clin Oral Implants Res. 2018;29(Suppl 15):7–10. doi:10.1111/clr.13110 Consensus
  3. Lin GH, Chan HL, Wang HL. The significance of keratinized mucosa on implant health: a systematic review. J Periodontol. 2013;84(12):1755–1767. doi:10.1902/jop.2013.120688 · PMID: 23451989 Syst. review
  4. Ramanauskaite A, Schwarz F, Sahin D, et al. Influence of width of keratinized tissue on the prevalence of peri-implant diseases: a systematic review and meta-analysis. Clin Oral Implants Res. 2022;33(Suppl 23):8–31. doi:10.1111/clr.13766 Syst. review

Evidence grades: Systematic review Consensus Preclinical. The 2 mm thresholds are pragmatic working values, not absolute cut-offs; graft selection and timing remain case-specific.

About this chapter

This chapter is part of Osseo IQ — a clinical reference for implant dentistry. Content is sourced from consensus statements, systematic reviews, and primary literature; each key recommendation carries an evidence grade, and every page records its review date. Material is reviewed on a rolling annual cycle.

How to cite: Khuu T, ed. Peri-implant Soft-Tissue Grafting. In: Osseo IQ, 1st ed. §4.6. June 2026. Accessed [date]. [URL]

Compiled by: Tan Khuu, DDS — Doctor of Dental Surgery and a licensed dentist in California and South Carolina. Osseo IQ summarizes published evidence and clinical guidelines and is not a substitute for individual clinical judgment. Image credits: Figure 1 original schematic illustration © Osseo IQ, 2026.

For licensed clinicians — educational use only. This chapter summarizes published evidence and is not a substitute for individual clinical judgment, examination, or the standard of care in your jurisdiction. Verify drug doses, devices, and protocols against current manufacturer instructions and local guidelines.

© 2026 Osseo IQ · Edition 1.0 · Chapter 4 Surgical · §4.6 · Last reviewed June 2026