A gap between teeth, known as a diastema, is common and most frequently occurs between the two upper front teeth (midline diastema). While spacing is not inherently harmful, it is often a normal developmental stage in children as permanent teeth emerge. A persistent diastema in adults or adolescents is caused by specific factors involving genetics, anatomy, and acquired habits. Determining the precise cause of the spacing is the first step toward effective correction.
Structural Causes of Diastema
A common anatomical reason for a midline gap involves the labial frenum, the small band of tissue connecting the upper lip to the gum tissue between the two front teeth. If the frenum is oversized or attaches too low on the gumline, it physically prevents the teeth from moving together. Dentists may classify a frenum as papillary or papillary penetrating if its fibers extend into the underlying bone, which is strongly associated with a persistent diastema.
Spacing can also arise from a mismatch between the size of the teeth and the jawbone, a condition largely determined by genetics. If an individual inherits a large jaw structure but relatively small teeth, the teeth will naturally erupt with spaces between them to fill the available arch length. This inherited disproportion creates generalized spacing throughout the dental arch.
Another structural factor involves missing or smaller-than-average teeth, which disrupts natural alignment and creates extra room. For example, the lateral incisors (adjacent to the front teeth) may be underdeveloped or undersized, a condition known as peg laterals. When these teeth are too small, surrounding teeth shift, causing the central incisors to move apart. Additionally, an extra tooth, such as a mesiodens growing behind the front teeth, can physically push the central incisors apart.
Behavioral and Pathological Factors
Diastema formation is also linked to chronic oral habits that exert repetitive physical force against the teeth. The constant, subtle pressure from tongue thrusting, an oral myofunctional habit, gradually pushes the front teeth forward and outward. This occurs when the tongue presses against the back of the front teeth during swallowing or speech instead of resting against the roof of the mouth.
Since a person swallows thousands of times daily, the slight force from the tongue repeatedly pushing against the teeth causes significant movement over time. Chronic habits like prolonged thumb-sucking or pacifier use in childhood similarly apply outward pressure that pushes teeth out of alignment. These habits can create an open bite, where the upper and lower teeth do not meet, further encouraging the tongue to push through the space.
A concerning cause for new or widening gaps in adult teeth is periodontal disease, a serious gum infection. Advanced periodontitis causes inflammation and the gradual destruction of the alveolar bone supporting the teeth. As bone is lost, the teeth lose stable anchoring and become mobile, leading to pathological tooth migration. This migration causes teeth to drift apart and create new spaces, necessitating immediate periodontal treatment before any cosmetic correction is pursued.
Treatment Pathways for Gap Closure
Addressing a diastema effectively requires treating the underlying cause, using professional methods to close or camouflage the gap. Orthodontic solutions are often the most comprehensive approach, using traditional braces or clear aligners to physically move the teeth together. This method applies controlled forces, gently repositioning the teeth within the jawbone to eliminate the space and achieve proper alignment of the entire dental arch.
For small gaps or those that are primarily a cosmetic concern, dental bonding and veneers offer non-orthodontic alternatives. Dental bonding involves applying a tooth-colored composite resin material directly to the sides of the adjacent teeth and shaping it to widen their appearance, filling the gap. Porcelain veneers are thin, custom-made shells bonded to the front surface of the teeth, achieving a similar effect by masking the space and improving smile aesthetics.
If a prominent labial frenum is the cause, a surgical procedure called a frenectomy may be performed. This procedure reduces the size or lowers the attachment point of the frenum, removing the physical barrier preventing the teeth from closing. A frenectomy is often performed with orthodontic treatment to prevent the diastema from relapsing. Following any corrective procedure, a retainer is necessary to hold the teeth in their new positions, as diastemas tend to reopen over time.