Gum recession and a visible metal edge after implant treatment? Three levels of assessment: appearance, cleaning, and hard and soft tissues

Gum recession and a visible metal edge after implant treatment? Three levels of assessment: appearance, cleaning, and hard and soft tissues

Direct answer: First separate whether the gingival margin has receded or whether colour is showing through thin mucosa — the two are managed differently. Where the problem is a buccal peri-implant soft tissue dehiscence, soft tissue augmentation appears to positively influence esthetic outcomes, but the review states that this is based on limited evidence, and complete coverage is not a given. [F3]

Geographic scope: global. Every figure here is taken from randomized controlled trials, systematic reviews and meta-analyses in international journals; none of it is written around the rules or funding arrangements of any single region. Which materials and techniques you can actually obtain still depends on your local care setting and your dentist's clinical judgement.

TL;DR｜‘Seeing metal’ usually reflects two overlapping issues

You may look in the mirror and notice that the area where your implant crown meets the gum has darkened, that a grey edge is showing, or even that the surface feels uneven. In the literature, this is not a single problem; it reflects the overlap of soft-tissue recession and colour showing through. Determining which situation applies requires assessment at three levels.

First, recession is closely related to your original hard- and soft-tissue conditions. A prospective study that followed 58 posterior implant restorations for 1 year reported statistically significant correlations between buccal mucosal recession and the initial buccal mucosal width (r = −0.381), initial width-to-height ratio (r = −0.422), and buccal bone width (r = −0.290). The study concluded that sites with thin mucosa, thin bone, and a low width-to-height ratio are more prone to buccal mucosal recession and vertical bone loss [F1].

Second, the direction of effect favours one crown shape (concave rather than convex), but the meta-analysis did not reach significance. A systematic review and meta-analysis of 4 randomised controlled trials involving 144 implants with 12 months of follow-up reported a pooled mean difference of −0.31 mm (95% CI −0.63 to 0.02; p = 0.064)—the confidence interval crossed 0, so the result was not statistically significant [F2].

Third, can it be repaired? Improvement is possible, but complete coverage is not inevitable. A systematic review and meta-analysis of 5 studies involving 87 patients reported that, after soft-tissue augmentation, defect depth decreased by a mean of 2.2 mm (95% CI 1.76 to 2.69) and the complete coverage rate was 71% (95% CI 59% to 82%). The review explicitly stated that these findings were based on limited evidence [F3].

The three levels are unpacked below.

1. First distinguish between gum recession and colour showing through

Clinically, there are two reasons why ‘metal is visible’, and their management is entirely different.

Source A: soft-tissue recession. The gingival margin moves apically, exposing an abutment or implant neck that was previously covered. This is a positional problem.

Source B: colour showing through thin mucosa. There may be no obvious gingival recession, but the soft tissue is thin enough for the colour of the metal abutment underneath to show through, making the area look grey or dark. This is a problem of thickness and material.

Abutment material really does affect aesthetic ratings

A randomised controlled clinical trial placed single implant-supported restorations in the anterior maxilla (incisors, canines, and premolars) of 30 patients, who were randomly assigned to receive either zirconia or titanium abutments. Aesthetic (Implant Crown Aesthetic Index, ICAI), clinical, radiographic, and patient-reported outcomes were recorded at baseline (1 month after placement of the definitive restoration), 1 year, and 5 years. The trial was registered at ClinicalTrials.gov (NCT02315794), and 25 participants completed both the 1-year and 5-year follow-ups [F4]:

• ICAI scores showed statistically significantly better aesthetic outcomes with zirconia abutments than with titanium abutments [F4]
• Between 1 year and 5 years, the crown component of the aesthetic subanalysis worsened, whereas the mucosal component improved [F4]
• Bone levels did not change significantly; however, plaque index, bleeding on probing, and probing depth worsened in both groups [F4]
• The trial concluded that, at 5 years, standard zirconia abutments achieved better aesthetic outcomes, but clinical performance was similar [F4]

It is worth pausing over the phrase ‘better aesthetics but similar clinical performance’. It means that changing to a zirconia abutment improves the visible colour and overall aesthetic rating, not the health of the implant or its bone level [F4]. If your main concern is a grey colour, this is an evidence-supported avenue; if the problem is a receded gingival position, changing the abutment material does not correct that position.

A cautious reading: this was a randomised controlled trial with only 30 patients, of whom 25 completed follow-up [F4]. The sample was small, and follow-up extended only to 5 years. Another easily overlooked detail is that plaque index, bleeding on probing, and probing depth worsened in both groups over the 5 years [F4]. This reminds us that the choice of abutment material cannot replace daily cleaning and regular maintenance.

2. Conditions associated with recession: what your hard and soft tissues were like to begin with

Of the three levels, this one best explains ‘why me?’.

Thin sites are more prone to recession

A prospective study included 58 posterior implant restoration cases and assessed them when the restoration was fitted (T0) and 1 year later (T1). It measured buccal mucosal width (BMW), buccal bone width (BBW), implant buccal inclination, and emergence angle, then analysed which variables affected mucosal recession (MR) and vertical bone loss (VBL) [F1]:

• Baseline values were buccal mucosal width 2.93 ± 1.01 mm and buccal bone width 1.50 ± 0.82 mm [F1]
• At 1 year, the buccal mucosal width-to-height ratio was 1.23 ± 0.38, significantly lower than the baseline value of 1.42 ± 0.45 [F1]
• Buccal mucosal recession was −0.22 ± 0.47 mm, and vertical bone loss was 0.81 ± 0.80 mm [F1]
• Recession was statistically significantly correlated with three factors: initial mucosal width (r = −0.381), initial width-to-height ratio (r = −0.422), and buccal bone width (r = −0.290) [F1]
• Vertical bone loss was statistically significantly correlated with four factors: initial mucosal width (r = −0.421), initial width-to-height ratio (r = −0.305), implant buccal inclination (r = 0.507), and buccal bone width (r = −0.556) [F1]
• The study concluded that, within its scope, implant sites with thin buccal mucosa, thin buccal bone, and a low width-to-height ratio were more prone to buccal mucosal recession and vertical bone loss [F1]

The two most useful signals in this section are:

First, the correlation coefficient between ‘implant buccal inclination’ and vertical bone loss was 0.507 — the only positive correlation among the four statistically significant variables: the greater the inclination, the greater the bone loss [F1]. It was not, however, the largest in absolute terms: within the same set, buccal bone width at −0.556 had the larger absolute value [F1]. This means that the three-dimensional position of the implant itself is a factor independent of soft-tissue thickness.

Second, the correlation coefficient between buccal bone width and vertical bone loss was −0.556, the strongest negative correlation [F1]. The thinner the bone, the greater the vertical bone loss.

A cautious reading (the limits on extrapolating this section are important): this study involved the posterior region [F1], whereas concern about visible metal most often arises in the anterior aesthetic region. Data from the posterior region can indicate the direction of the mechanism (thin sites are more prone to recession), but cannot be used directly as a quantitative expectation for the anterior region.

Moreover, these are correlation coefficients. The strongest was 0.556, which corresponds to a coefficient of determination of approximately 31%; in other words, nearly seven-tenths of the variation came from other factors. Correlation is not causation, and a sample of 58 cases followed for 1 year cannot support stronger inferences. Finally, mean recession over 1 year was only 0.22 mm [F1]. This was an average, and individual variation may be substantial (the standard deviation of 0.47 mm exceeded the mean itself).

Width of keratinised mucosa: associated with cleaning and inflammation

Another frequently discussed soft-tissue measure is keratinised mucosal width—the width of the firmer, pink band of gingiva that does not move when pulled.

A systematic review and meta-analysis searched PubMed, Web of Science, CNKI, and VIP up to May 2024 and calculated mean differences and 95% confidence intervals for plaque index (PI), gingival index (GI), bleeding index (BI), probing depth (PD), clinical attachment loss (CAL), and bone loss (BL). A total of 30 articles were included [F5]:

• Implants with an adequate keratinised mucosal width (≥ 2 mm) had a significantly lower plaque index: mean difference −0.30 (95% CI −0.42 to −0.17) [F5]
• Gingival index: mean difference −0.26 (95% CI −0.38 to −0.13) [F5]
• Bleeding index: mean difference −0.20 (95% CI −0.33 to −0.07) [F5]
• Bone loss: mean difference −0.27 (95% CI −0.42 to −0.12) [F5]
• The analysis concluded that an adequate width of keratinised mucosa around implants (≥ 2 mm) was associated with less plaque accumulation, tissue inflammation, and bone loss [F5]

Note the role of this study: it concerns cleaning and inflammation, not aesthetic recession. All four significant findings point towards ‘easier to clean, less inflammation, and less bone loss’, which is a functional rationale [F5].

A cautious reading: the analysis explicitly reported significant heterogeneity among the included studies, although sensitivity analyses indicated that the results were robust [F5]. It also originally calculated six outcomes (PI, GI, BI, PD, CAL, and BL), but the results section of the abstract listed only four as significant—probing depth and clinical attachment loss were not listed among the significant findings. This should be remembered when interpreting the conclusion that ‘keratinised mucosa is important’. The four effect sizes were −0.30, −0.26, −0.20, and −0.27; none was large.

3. Crown emergence profile: concave appears preferable, but the meta-analysis did not reach significance

This section contains the data that require the most careful interpretation.

A systematic review and meta-analysis assessed the effect of a concave versus convex emergence profile on mid-buccal mucosal stability. It included only randomised controlled trials, was registered with PROSPERO (CRD420251139042), searched MEDLINE (PubMed) and Embase up to 7 May 2026, assessed risk of bias with RoB 2, and used a random-effects model to calculate the weighted mean difference [F2]:

• It included 4 randomised controlled trials, 144 implants, and 12 months of follow-up; 128 implants entered the quantitative synthesis (66 in the concave/modified group and 62 in the convex/non-concave group) [F2]
• The pooled mean difference was −0.31 mm (95% CI −0.63 to 0.02; p = 0.064), indicating a trend towards more mid-buccal mucosal recession with a convex emergence profile [F2]
• Between-study heterogeneity was low to moderate (I² = 28%), indicating that the results of the studies were fairly consistent [F2]
• Sensitivity analyses confirmed the direction of the effect, with pooled estimates ranging from −0.12 to −0.43 mm [F2]
• After one study was excluded, the result became statistically significant in favour of a concave profile: −0.43 mm (95% CI −0.70 to −0.16; p = 0.002) [F2]
• The review concluded that a convex emergence profile was associated with a trend towards increased mid-buccal mucosal recession; a concave profile was preferable, and emergence-profile design should be regarded as part of prosthetic and surgical planning [F2]

A cautious reading (each point here must be considered separately):

First, the primary analysis did not reach statistical significance. The 95% confidence interval was −0.63 to 0.02, its upper bound crossed 0, and p = 0.064 was also above the conventional threshold of 0.05 [F2]. This means that the possibility of no difference between the two profiles cannot be ruled out. The source paper used the wording ‘a trend toward’, not ‘significantly better’—that distinction matters.

Second, significance was reached only after one study was excluded. The value −0.43 mm (p = 0.002) was a sensitivity-analysis finding obtained after one study had been removed [F2]. In a meta-analysis of only 4 trials, removing one eliminates one-quarter of the data; such a finding is exploratory and carries less weight than the primary analysis.

Third, the effect size itself was small. Even the largest sensitivity-analysis estimate, −0.43 mm, represents a difference of less than half a millimetre [F2]. It may be statistically meaningful, but whether it produces a visible aesthetic difference is a separate question.

Fourth, the evidence base was thin. There were only 4 randomised controlled trials, 144 implants, and 12 months of follow-up [F2]. In the context of soft-tissue stability, 12 months is short-term follow-up.

The honest interpretation, therefore, is that a concave emergence profile appears favourable in direction, and low heterogeneity (I² = 28%) suggests that this direction was fairly consistent; however, current evidence is insufficient to establish a statistically significant advantage, and the effect size was also below 0.5 mm [F2]. Treating it as ‘a design option worth considering during planning’ is reasonable. Treating it as ‘changing to a concave profile will prevent recession’ goes beyond what the evidence supports.

4. If recession has occurred and metal is already visible, can it be repaired?

Improvement is possible, and the literature provides numerical estimates of that improvement; however, ‘complete coverage’ is not inevitable.

Real-world outcomes of coverage surgery

A systematic review and meta-analysis evaluated soft-tissue augmentation (STA) for buccal peri-implant soft-tissue dehiscence (PSTD). Its protocol followed the PRISMA checklist, and it included cases without coexisting peri-implantitis, randomised clinical trials, and prospective studies with at least 6 months of follow-up. A total of 8 publications covering 5 studies (2 randomised controlled trials and 3 prospective studies), published between 2013 and 2024 and involving 87 patients, were included. All studies used a coronally advanced flap (CAF) with a connective tissue graft (CTG) or a substitute material; one arm of one randomised controlled trial used a tunnel technique, and two studies also replaced prosthetic components. Of the studies, 3 were judged to have a low risk of bias, and 10 meta-analyses were performed [F3]:

• The final professionally assessed aesthetic score was 7.7 points (0-to-10 scale; 95% CI 6.63 to 8.83) [F3]
• The pooled patient-reported aesthetic value (0-to-100 visual analogue scale) was 60.8 (95% CI 46.56 to 75.01), with moderate to high heterogeneity; the source states only that the procedures showed improvements in terms of patient-reported esthetics and gives this pooled value, without specifying whether 60.8 is the post-treatment score or the size of the improvement, so this card does not choose one reading for it [F3]
• The estimated reduction in defect depth was 2.2 mm (95% CI 1.76 to 2.69) [F3]
• The estimated proportion achieving complete coverage was 71% (95% CI 59% to 82%) [F3]
• The review concluded that, based on limited evidence, soft-tissue augmentation appeared to have a positive effect on both professionally assessed and patient-reported aesthetic outcomes [F3]

How should ‘71% complete coverage’ be read? Its 95% confidence interval was 59% to 82% [F3], meaning that approximately 1 to 2 people out of every 5 to 6 would not achieve complete coverage. This is a fairly good result, but it is clearly not a guarantee of complete coverage. When discussing treatment at a follow-up visit, the interval is more important to remember than the single figure of 71%.

A cautious reading: the review itself used the phrase ‘based on limited evidence’ in its conclusion [F3]. The reasons are clear: there were only 5 studies and 87 patients; only 2 studies were randomised controlled trials, and 3 were judged to have a low risk of bias (meaning that the other two were not) [F3]. In addition, the pooled patient-reported aesthetic outcome had moderate to high heterogeneity [F3], and its confidence interval ran from 46.56 to 75.01—a span of nearly 30 points, indicating limited precision.

One further inclusion criterion must be noted: the review included only cases without coexisting peri-implantitis [F3]. If recession is accompanied by infection, these figures do not apply — and whether infection is present is not only a question of which literature applies; it changes the order of priorities: if there is persistent redness and swelling around the implant, pus on pressure or spontaneously, bleeding at times other than brushing, pain on biting, or a sense that the implant is loose, contact a dentist promptly for an examination rather than booking esthetic surgery first (this is an editorial triage note from this card, not from the sources listed above).

Which material should be used?

A PRISMA-guided systematic review assessed the medium- to long-term predictability (6 to 60 months) of peri-implant soft-tissue augmentation techniques. It included randomised controlled trials with at least 10 participants per group that used bilaminar or apically positioned flap techniques, and compared autogenous grafts with substitute materials (collagen matrices, acellular dermal matrices, and volume-stable collagen matrices). A total of 27 randomised controlled trials met the inclusion criteria [F6]:

• Implant survival exceeded 95% in every study [F6]
• Connective tissue grafts (CTG) consistently produced the greatest gains in keratinised mucosal width, mucosal thickness, soft-tissue margin stability, and aesthetic outcomes, particularly in the anterior and aesthetic regions [F6]
• Overall, autogenous grafts performed better in maintaining marginal bone levels; volume-stable collagen matrices showed acceptable long-term stability and caused less donor-site discomfort [F6]
• The review concluded that connective tissue grafting remained the most predictable method for long-term soft-tissue stability and aesthetics. Acellular dermal matrices, collagen matrices, and volume-stable collagen matrices were useful alternatives when reducing discomfort was the priority, but their outcomes were more variable [F6]

In practical terms, this means that if your main objective is soft-tissue thickness and marginal stability in the anterior aesthetic region, a connective tissue graft taken from your own mouth is currently the most predictable option [F6]. Substitute materials have the advantage of avoiding a second donor-site wound, at the cost of greater variability in outcomes [F6]. This is a classic trade-off, with no single correct answer.

5. A framework for assessment at your follow-up visit

These three levels can be translated into specific points to take to your dental appointment.

Three things you can describe proactively

1. Has the position changed, or has the colour changed? Look in the mirror: compared with the adjacent natural teeth, has the gingival margin moved upwards (or downwards)? Or is its position about the same, with a grey or dark band? These two situations point towards different management approaches—the former lies within the scope of soft-tissue augmentation [F3], whereas the latter may be related to abutment material and mucosal thickness [F4].

2. When did you notice it, and is it continuing to change? Prospective data indicate that mean buccal mucosal recession over 1 year was 0.22 ± 0.47 mm, with concurrent vertical bone loss of 0.81 ± 0.80 mm [F1]. Change is generally gradual, so knowing when you first noticed it is useful information.

3. Is there associated bleeding, swelling, or discomfort? Treat this first as a signal to be seen, not merely as a question of which evidence applies: persistent redness and swelling of the gum, pus on squeezing or spontaneously, bleeding at times other than brushing, pain around the implant or a sense that it is loose all mean you should arrange a dental examination promptly (this is an editorial triage note from this card, not from the sources listed above). At the level of the evidence, the soft-tissue augmentation meta-analysis included only cases without coexisting peri-implantitis [F3]. If infection is present, the order of management priorities is different.

Four questions you can ask

Question 1: Is my keratinised mucosa wide enough? The meta-analysis reported that a keratinised mucosal width ≥ 2 mm was associated with less plaque (mean difference −0.30), gingival inflammation (−0.26), bleeding (−0.20), and bone loss (−0.27) [F5]. This is a marker of cleanability and health, not a direct measure of aesthetics.

Question 2: How thick are my buccal bone and mucosa? Prospective data suggest that sites with thin mucosa, thin bone, and a low width-to-height ratio are more prone to recession, and that the strongest correlation was between buccal bone width and vertical bone loss (r = −0.556) [F1]. Imaging is usually required to assess this.

Question 3: If I have soft-tissue augmentation, how much improvement can I expect? The figures in the literature are: a mean reduction in defect depth of 2.2 mm (95% CI 1.76 to 2.69), a complete coverage rate of 71% (95% CI 59% to 82%), and a professional aesthetic score of 7.7 / 10 [F3]. Remember the range from 59% to 82%, rather than only the figure of 71%.

Question 4: Should tissue from my own mouth or a substitute material be used? Connective tissue grafting produced the greatest gains in keratinised mucosal width, mucosal thickness, marginal stability, and aesthetics, particularly in the anterior aesthetic region. Substitute materials caused less donor-site discomfort but had more variable outcomes [F6]. This is a trade-off worth discussing in light of your priorities.

All of these questions can be answered properly only after a dentist has performed a clinical examination and any necessary imaging, including assessment of hard- and soft-tissue thickness. The purpose of this article is to help you understand what to describe, what to ask, and what expectations to bring to the answers.

Conclusion｜First distinguish between recession and show-through, then consider whether surgery is appropriate

The three levels can be distilled into one sentence: when metal is visible after implant treatment, first distinguish whether the gingival position has receded or colour is showing through thin mucosa—the answer to the former lies in soft-tissue augmentation, whereas the latter may relate to abutment material and mucosal thickness.

The three strands of evidence differ markedly in strength and should be remembered separately:

• Association between hard- and soft-tissue conditions and recession: sites with thin mucosa, thin bone, and a low width-to-height ratio were more prone to recession. The strongest correlation was between buccal bone width and vertical bone loss (r = −0.556), followed by implant buccal inclination (r = 0.507) [F1]. However, these were 1-year correlational data from the posterior region; they cannot be interpreted as causal or directly extrapolated to the anterior region.
• Crown emergence profile: the direction favoured a concave profile and heterogeneity was low (I² = 28%), but the primary analysis was not significant (−0.31 mm, 95% CI −0.63 to 0.02, p = 0.064), and the effect size was below 0.5 mm [F2]. At present, this evidence supports only the position that it is ‘worth considering during planning’.
• Actual outcomes of repair: mean defect depth decreased by 2.2 mm, the complete coverage rate was 71% (95% CI 59% to 82%), and the professional aesthetic score was 7.7 / 10 [F3]. In material selection, connective tissue grafting was the most predictable option in the aesthetic region, whereas substitute materials traded less donor-site discomfort for greater variability in outcomes [F6].

One further point should not be overlooked: the 5-year randomised controlled trial reported that, regardless of which abutment was used, plaque index, bleeding on probing, and probing depth worsened over the 5 years [F4]. This reminds us that even the best choices of material and shape cannot replace daily cleaning and regular maintenance.

The next step is straightforward: bring three pieces of information to your appointment—whether the position has receded or the colour has changed, when you first noticed it, and whether it is accompanied by bleeding or discomfort. You are welcome to book a comprehensive assessment with a dentist. First establish which level applies to your situation and assess the thickness of the hard and soft tissues; then discuss whether to adjust the restoration, undertake soft-tissue augmentation, or begin with enhanced maintenance and monitoring. Diagnosis should precede intervention, so that surgery does not leave the true cause unaddressed.

Risk factors (what to know before treatment)

• Indications and the boundary of applicability: the esthetic outcome data for soft tissue augmentation come from randomized clinical trials and prospective studies on implants without peri-implantitis, with a follow-up of at least 6 months [F3]. If the recession is accompanied by infection, these figures do not apply.
• Check first for signs of infection (editorial triage note from this card, not from the sources listed above): persistent redness and swelling around the implant, pus on pressure or spontaneously, bleeding at times other than brushing, pain on biting, persistent bad breath, or a sense that the implant is loose all mean you should contact a dentist promptly for an examination rather than booking esthetic surgery first; if there is fever, swelling that keeps spreading, or any effect on swallowing or breathing, seek care immediately.
• Who is more likely to be affected: the prospective study concluded that, within the scope of that study, implant sites in the posterior region presenting a thin buccal mucosa width, a thin buccal bone width and a small width/height ratio are more prone to exhibit buccal mucosa recession and vertical bone loss [F1]. That is posterior-region data and should not be extrapolated directly into quantitative expectations for the anterior esthetic zone.
• Adverse effects and complications: the review recorded that substitute materials (acellular dermal matrix, collagen matrix, volume-stable collagen matrix) are useful alternatives when reduced morbidity is prioritized, although their outcomes are more variable [F6]. The other side of “less donor-site morbidity” is that taking autogenous tissue adds a second surgical site.
• What cannot be expected: in the emergence-profile meta-analysis the primary analysis did not reach statistical significance, and the wording used was a “trend” rather than an established advantage [F2]. Changing a crown to a concave profile therefore cannot be treated as a way to avoid recession.
• Maintenance and long-term follow-up: in the randomized controlled trial with 5 years of follow-up, the plaque index, bleeding on probing and probing depths worsened in both groups [F4]; the meta-analysis also found that an adequate width of keratinised mucosa (≥ 2 mm) around dental implants is associated with reduced plaque accumulation, tissue inflammation and bone loss [F5]. The choice of material and contour does not replace daily cleaning and regular maintenance.

Every clinical statement in this article is mapped line by line to its cited source (see the sources and evidence chain below). It has not been clinically reviewed by a licensed practitioner. This is health information, not individual advice; assessment by a clinician is required.