What Connects Lip to Gums? The Labial Frenum Explained

A small fold of tissue called the labial frenum (sometimes spelled “frenulum”) is the thin band that tethers your lip to your gum. You can feel it right now: curl your upper lip upward with a finger and you’ll find a narrow ridge of tissue running from the inside of your lip down to the gum above your front teeth. A matching fold exists behind your lower lip, though it tends to get less attention. The labial frenum is a normal anatomical structure that everyone has, but its size, thickness, and attachment point vary considerably from person to person, and those variations sometimes create real dental or feeding problems worth understanding.

What the Frenum Is Actually Made Of

Despite being attached near muscle, the labial frenum itself is not muscular. Histological studies have found that it consists primarily of dense collagen fibers, loose connective tissue, and elastic fibers, with no muscle fibers in the frenum proper.¹ A more recent anatomical investigation confirmed this picture, describing the upper labial frenum as a mucosal fold between the gingival mucosa and the alveolar mucosa, with connective tissue beneath it that attaches to the bone at the midline junction between the left and right sides of the upper jaw.² In that study, skeletal muscle fibers other than the orbicularis oris (the ring-shaped muscle that forms the bulk of the lip) were found in only a single specimen, suggesting that muscle involvement in the frenum is the rare exception rather than the rule.

Think of the frenum as essentially a curtain of collagen draped in a mucous-membrane lining. It has a blood supply, which is why it bleeds briskly if torn, but it doesn’t contract or move independently the way a muscle would. The upper and lower labial frena also differ structurally. Dissections have shown that the connective tissue under the upper frenum is thin and taut, while the tissue under the lower frenum is thicker, flatter, and occupies the space between the left and right mentalis muscles (the small paired muscles in your chin).³

Where the Frenum Attaches and Why It Matters

Not all frena attach in the same spot, and the attachment point is one of the main things clinicians look at when deciding whether a frenum could be causing problems. A widely used classification system sorts frenal attachments into four types based on how close to the teeth the tissue inserts:

Mucosal: the frenum attaches at or near the mucogingival junction (the transition line between the movable inner-lip tissue and the firmly attached gum), well away from the teeth.
Gingival: the frenum inserts into the attached gingiva but doesn’t reach the gum tissue between the front teeth.
Papillary: the frenum extends to the base of the papilla (the triangular bit of gum between the two upper front teeth).
Papillary penetrating: the frenum goes beyond the papilla and its pull can be seen or felt all the way through to the palatal side of the gum.

This classification was developed by Placek and colleagues and remains the standard in dental literature.⁴ The mucosal type is the most common in people with normal jaw relationships, while the higher-inserting types become clinically significant because they can pull on the gum tissue and contribute to spacing between the front teeth.

Interestingly, frenum morphology isn’t entirely random. A cross-sectional study of different skeletal jaw patterns found that mucosal-type attachment was most common in people with typical or slightly receded jaw profiles (skeletal Class I and II), while the gingival type was most common in those with a protruding lower jaw (skeletal Class III). The papillary and papillary-penetrating types were significantly more common in the Class III group and were associated with midline spacing between the upper front teeth.⁵ The implication is that your overall jaw structure may influence where and how your frenum develops.

The Gap Between the Front Teeth

One of the most common questions about the labial frenum is whether it causes a diastema, the visible gap between the two upper front teeth. The relationship is real but more nuanced than many patients expect. A systematic review of the dental literature found that two specific subtypes of frenum attachment — papillary and papillary penetrating — are associated with midline diastema.⁶ In other words, a frenum that inserts far enough toward (or through) the gum between the teeth appears to physically prevent the gap from closing on its own.

However, a thick frenum in a young child is often completely normal and shouldn’t be treated reflexively. In children who still have their baby teeth, a prominent gap is expected — it typically narrows as the permanent canines come in and push the incisors together. Removing the frenum surgically before the permanent teeth have fully erupted can leave scar tissue that actually makes orthodontic closure harder. Most orthodontists and pediatric dentists now recommend waiting to see whether the gap persists after the canines erupt, then addressing the frenum if it does.

There is also a hereditary dimension. A case report documenting the same pattern of midline diastema and high frenal attachment in both a mother and her daughter suggests a genetic component to frenum positioning and associated spacing.⁷ If your parent had a prominent gap and thick frenum, you may be more likely to have one too.

Lip-Tie in Babies and the Breastfeeding Debate

In recent years, “lip-tie” has become a major talking point among parents struggling with breastfeeding. The idea is straightforward: if an infant’s upper labial frenum is unusually thick or low-attaching, it might restrict the upper lip’s ability to flange outward during nursing, leading to a poor latch, nipple pain, and inadequate milk transfer.⁸

The clinical reality is considerably murkier than social-media parenting groups tend to suggest. A systematic review on upper lip-tie and breastfeeding found no randomized controlled trials on the topic and concluded that the evidence for routinely releasing the upper lip frenum in infants with feeding difficulties is poor. The Kotlow classification system, which is widely used on parenting websites to grade lip-tie severity, was found to have unreliable inter- and intra-observer agreement and did not reliably predict the severity of breastfeeding problems.⁹

A separate study that directly examined the relationship between upper lip anatomy and breastfeeding success scores found no correlation between lip-tie classification and breastfeeding outcomes. The same study also found no relationship between tongue-tie measurements and visualized lip anatomy, suggesting that tongue-tie and lip-tie do not necessarily cluster together in the same infant, even though they are often discussed as a package.¹⁰

None of this means that lip-ties never cause feeding difficulties. Individual infants may genuinely struggle because of frenum restriction, and experienced lactation consultants sometimes observe dramatic improvement after release. The problem is that the current evidence cannot tell us reliably who those infants are, and the classification tools being used to diagnose “significant” lip-tie are not yet validated. Parents navigating this space should be cautious about providers who diagnose lip-tie based on appearance alone and recommend immediate surgical release without a thorough feeding evaluation.

How the Frenum Affects Oral Hygiene

A frenum that attaches high on the gum doesn’t just affect spacing — it can also make keeping your teeth clean more difficult. The tissue gets in the way of a toothbrush, especially when trying to clean the gum line around the upper front teeth. A high frenum attachment can tug on the gum tissue when the lip moves, which over time may contribute to gingival recession (where the gum pulls away from the tooth, exposing the root).¹¹

Research on frenal attachment types and oral hygiene status in adolescents confirmed this practical problem, noting that the force a high frenum exerts on the gingiva can affect healing and tissue integrity.⁴ In periodontal surgery, the frenum’s attachment level also matters for planning tissue grafts and choosing between different surgical flap approaches.¹² After frenectomy (surgical removal or repositioning of the frenum), patients in at least one study showed significant improvement in their ability to maintain oral hygiene in the area.¹¹

When and How a Frenectomy Is Done

A frenectomy — the procedure to remove, reposition, or release the frenum — is one of the most common minor oral surgeries. It’s performed in adults and children for several reasons: to help close a persistent diastema (usually alongside orthodontic treatment), to relieve gum pull that is causing recession, to improve denture fit, or to address feeding difficulties in infants. The procedure itself is quick, usually taking somewhere between 15 and 21 minutes depending on the technique used.

The traditional approach uses a scalpel and sutures. More recently, diode lasers have become a popular alternative, and multiple randomized trials have compared the two. The findings are fairly consistent across studies: laser frenectomy produces less pain in the first week after surgery. One randomized controlled trial found that diode laser patients had significantly lower pain scores on days 1, 3, and 7 compared to the scalpel group, though the difference disappeared by day 14.¹³ A separate trial comparing two wavelengths of diode laser against a scalpel found that both laser types resulted in less intraoperative bleeding, less chewing and speaking discomfort, and faster tissue healing at one week.¹⁴

A third comparative study that also included electrocautery in the comparison found the diode laser superior across all measured outcomes, with the shortest procedure time, fastest healing, and lowest pain levels.¹⁵ However, there’s a counterpoint worth noting: one randomized trial found that healing at one week was actually faster in the scalpel group, and that by the final follow-up, tissue healing and the long-term outcome (including whether the frenum reattached) showed no difference between the techniques.¹³ Another trial came to a similar conclusion: both conventional and laser-assisted frenectomy prevented frenum reattachment, and the main advantage of the laser was better comfort during recovery rather than a fundamentally different long-term result.¹⁶

The bottom line for patients is that both approaches work well. The laser offers a somewhat more comfortable recovery in the first week, but the end result at a month or six months tends to be the same. The choice often comes down to what your dentist or surgeon is equipped to offer and whether you place a premium on minimizing short-term discomfort.

Lower Labial Frenectomy

Most of the clinical attention goes to the upper labial frenum, but the lower one can cause its own problems. A high or tight lower frenum can contribute to gingival recession on the lower front teeth — an area particularly vulnerable because the bone and gum tissue there are naturally thin. A pilot study on lower labial frenectomy using a diode laser found that all patients in the sample had gingival recession and dentinal hypersensitivity before the procedure. Thirty days after laser frenectomy, pain had resolved in all but one patient, and the procedure was effective in reducing bleeding and improving scar appearance.¹⁷ That study was small — only three patients — so the numbers shouldn’t be taken as representative, but it illustrates that the lower frenum gets clinical attention when it contributes to recession or sensitivity.

What a Torn Frenum Means

The labial frenum tears fairly easily. A child who falls and hits their mouth on a table edge, or an adult who takes an elbow to the face during a basketball game, may bleed heavily from a torn upper frenum. In most cases, the tear heals on its own without stitches, and many dentists will simply advise cleaning the area gently and monitoring for infection. A torn frenum in a child is one of the most common minor oral injuries.

Historically, a torn frenum in a pre-mobile infant (a baby too young to crawl or walk) was considered a red flag for inflicted injury, on the assumption that a baby lying in a crib shouldn’t be able to sustain that kind of trauma accidentally. The reality is more complicated. A systematic review of torn frena and other intra-oral injuries concluded that current literature does not support a diagnosis of abuse based on a torn labial frenum in isolation.¹⁸ The review recommended that the entire intra-oral region be examined and a dental opinion sought when abnormalities are found, rather than jumping to conclusions from a single finding. A separate review of non-osseous injury patterns in child abuse cases reached the same conclusion, noting that frenum tears are not uniquely an inflicted injury.¹⁹ A torn frenum should prompt careful evaluation of the full picture, but it is not, on its own, proof of anything.

The Frenum and Dentures

For people who wear a full upper denture, the labial frenum creates a practical challenge that most tooth-having adults never think about. The denture’s acrylic base must have a notch cut into it to accommodate the frenum; otherwise, the frenum pushes against the denture and can dislodge it every time the lip moves. The size of that notch matters more than you’d guess. A finite-element analysis — essentially a computer simulation of stress distribution — found that the labial frenum notch was the single greatest point of stress concentration in a maxillary complete denture. Stress increased as the notch got larger, and the effect was compounded in patients with a shallow palatal vault (a flatter roof of the mouth).²⁰ In practical terms, a bulky frenum that requires a deep notch can make a denture more prone to cracking at that point. Some prosthodontists will recommend frenectomy before fabricating a denture to give the appliance a better chance at long-term survival.

Changes Over a Lifetime

The labial frenum isn’t static. In infants and young children, the upper frenum often appears thick and prominent, sometimes extending all the way to the palatal papilla behind the front teeth. As the jaw grows and the permanent teeth erupt, the frenum typically migrates upward and thins out. This is why early surgical intervention is usually discouraged — many frena that look abnormal at age four are perfectly unremarkable by age twelve. The classic guidance is to wait until after the upper permanent canines have come in (usually around age 11 to 13) before deciding whether a frenectomy is needed for diastema closure.

In older adults, the frenum can change again. Tooth loss and bone resorption alter the landmarks that the frenum attaches to, sometimes leaving it in a position that interferes with denture stability or causes irritation against prosthetic appliances. Gum disease can also affect the tissue around the frenum, and recession caused or worsened by frenal pull may expose roots and increase sensitivity. The frenum, in other words, is a minor structure whose clinical significance rises and falls with each stage of life — barely noticed most of the time, but worth paying attention to during the handful of moments when it can genuinely cause trouble.

1
PubMed. Histologic features of the superior labial frenum
2
PubMed. What is a superior labial frenulum? An anatomical and histological study
3
PubMed Central. Clinical Anatomy of the Frenulum of the Oral Vestibule
4
PubMed Central. Frenal attachment and its association with oral hygiene status among adolescents in Dakshina Kannada population: A cross-sectional study
5
PubMed Central. Prevalence of variations in morphology and attachment of maxillary labial frenum in various skeletal patterns – A cross-sectional study
6
PubMed. Association between superior labial frenum and maxillary midline diastema – a systematic review
7
Medical Journal of Clinical Trials & Case Studies. Mind the Gap Familial Maxillary Midline Diastema and High Labial Frenum Attachment
8
PubMed. Diagnosing and understanding the maxillary lip-tie (superior labial, the maxillary labial frenum) as it relates to breastfeeding
9
PubMed. Upper Lip Tie and Breastfeeding: A Systematic Review
10
PubMed. Upper Lip Tie: Anatomy, Effect on Breastfeeding, and Correlation With Ankyloglossia
11
PubMed Central. Paralleling technique for frenectomy and oral hygiene evaluation after frenectomy
12
Indian Journal of Forensic Medicine & Toxicology. Epidemiological Study Evaluating Type of Labial Frenum, Attachment Level and Gingival Biotypes in Chennai Population
13
PubMed Central. Evaluating diode laser and conventional scalpel techniques in maxillary labial frenectomy for patient perception, tissue healing, and clinical efficacy: six-month results of a randomized controlled study
14
PubMed Central. Maxillary labial frenectomy: a randomized, controlled comparative study of two blue (445 nm) and infrared (980 nm) diode lasers versus surgical scalpel
15
Clinical Dentistry. Comparative Evaluation for Labial Frenectomy: Insights into Healing, Pain, and Surgical Time Efficiency of Scalpel, Electrocautery, and Diode Laser Techniques
16
PubMed. Evaluation of Patient’s Perceptions, Healing, and Reattachment After Conventional and Diode Laser Frenectomy: A Three-Arm Randomized Clinical Trial
17
PubMed. Clinical evaluation of pain perception and surgical wound healing after lower labial frenectomy with diode laser technique: pilot study
18
PubMed Central. Diagnosing abuse: a systematic review of torn frenum and other intra‐oral injuries
19
PubMed Central. Are There Hallmarks of Child Abuse? II. Non-Osseous Injuries
20
PubMed. Effect of labial frenum notch size and palatal vault depth on stress concentration in a maxillary complete denture: a finite element study