Midline Diastema

What Is Midline Diastema?

Midline diastema is malocclusion having space in between maxillary or/and mandibular incisors. Maxillary incisors are more commonly affected than mandibular incisors. In the case of growing young children, midline diastema is self-correcting, as it is called the ugly duckling stage. Most parents of growing children get anxious when they notice a gap between their children's front teeth, but as it is self-correcting, it is not a reason for worry.

But in some cases, midline diastema does not get closed spontaneously. In those cases, proper diagnosis is important to rule out the cause. Fleshy labial frenum, habits, muscular imbalance, etc., can be the cause. Timing of the treatment is very important for satisfactory results. Many orthodontists do not advise tooth movement until the eruption of the permanent canines, but in cases of large spaces, early treatment is required.

What Are the Causes of Midline Diastema?

There are a number of causes for midline diastema. The common causes include:

1. Macrognathia (the condition wherein the lower jaw is abnormally large or protruding).

2. Microdontia (the condition in which the lower jaw is smaller in size than normal).

3. Hereditary (If one of the parents has midline diastema, their children may also have it).

4. Racial.

5. Mild generalized spacing of teeth.

6. Tooth size-arch length discrepancy. When the available space is more than the tooth material, which will accommodate there, it will lead to spacing and can result in midline diastema. Occurs in conditions such as missing teeth, microdontia, macrognathia, and extractions resulting in drifting of adjacent teeth.

7. Developmental or ugly duckling stage or transient malocclusion. During the mixed dentition period associated with the eruption of the permanent canines, a stage called the ugly duckling stage occurs. When permanent canines erupt, they displace the roots of lateral incisors mesially (towards the midline of the arch), resulting in transmitting the force onto the roots of the central incisors, which also get displaced mesially that leads to distal divergence of the crowns of the two central incisors causing a midline diastema. This is a self-correcting stage, so there is no need to worry as parents get anxious after observing space between the teeth in their growing children.

8. Physiological spacing in between deciduous teeth.

9. Congenitally missing teeth (by birth).

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10. Peg laterals (lateral incisors do not develop correctly and are small and pointed).

11. Presence of supernumerary teeth (extra teeth).

12. Extraction of teeth.

13. Ectopic eruption of teeth (disturbance in the usual course of tooth eruption).

14. Midline cystic lesions.

15. Increased overjet (too much horizontal gap between the upper and lower front teeth).

16. Increased overbite (upper teeth excessively overlap the lower front teeth).

17. Thumb sucking.

18. Tongue thrusting (tongue presses forward too far in the mouth).

19. Abnormal labial frenum (a thick and fleshy labial frenum that gives rise to midline diastema). This kind of frenal attachment prevents the two central incisors from approximating each other as there is obstruction because of the thick fibrous tissue of the frenum.

20. Retained deciduous teeth (baby teeth).

21. Palatally erupted lateral incisor.

22. During rapid palatal expansion; Midline diastema can occur in certain therapeutic procedures, like in the case of rapid palatal expansion. This comes under iatrogenic cause.

What Are the Diagnostic Tests to Determine Midline Diastema?

The following tests are useful for diagnosing midline diastema:

1. Case History and Clinical Examination - A proper history and clinical examination are necessary.

2. Blanch Test - A blanch test is performed to diagnose a fleshy labial frenum. It is done by pulling the upper lip outwards. The presence of a thick and fleshy frenum is confirmed by the blanching of the tissue in the incisive papilla region palatal to the central incisors.

3. Radiographs - On the radiograph, notching is seen in the interdental alveolar bone, which is a diagnostic sign of a thick fleshy frenum. Midline radiographs are a valuable aid in diagnosing midline pathology that causes spacing.

4. Model Analysis - Model analysis is essential for determining tooth material-arch length discrepancy, one of the causes of midline diastema.

How Can Midline Diastema Be Corrected?

Treatment can be divided into three stages:

Phase 1 - Removal of Causes.

Removal of the cause is very essential before the institution of treatment, as it is a major reason for treatment failure. It includes -

• Extraction of supernumerary teeth.

• Surgical removal of an abnormal frenum.

• Surgical removal of midline cystic lesions.

The following are a few etiological factors and treatments for midline diastema:

1. Tongue Thrust - Fixed or removable appliance with tongue rake.

2. Thumb Sucking - Fixed or removable appliance with tongue rake.

3. High Frenal Attachment - Frenectomy with or without gingivoplasty.

4. Supernumerary Teeth - Extraction.

5. Peg Laterals or Microdontia - Composite build-up or crowns.

6. Missing Laterals - Bridges or crowns.

Phase 2 - Active Treatment.

Midline diastema can be corrected by using one of the following removable orthodontic appliances incorporating finger springs, finger springs with a labial bow, and a split labial bow. Midline diastema can also be corrected by following sectional fixed appliance or fixed appliance like:

1. Pin and tube appliance.

2. Band the maxillary central incisors and attach brackets or buccal tubes.

3. Place a sectional archwire and use elastic force in the form of a figure of 8 or elastic modules.

In case of a missing lateral incisor, we have to gain space for the lateral incisor by using a space regainer for the replacement of the missing lateral, or if there is inadequate space for the replacement of missing laterals, canines can be brought forward, and recontoured M shaped springs incorporating three helices can also be used. If the spacing is due to microdontia, suitable crowns can be used.

Phase 3 - Retention.

Midline diastema is difficult to retain. The key to successful management is the elimination of etiological factors. Most orthodontists recommend long-term retention using suitable retainers. For prolonged retention, lingual bonded retainers are advised, such as banded retainers and Hawley’s retainers.

Role of Cosmetic Restorations:

In adult patients, esthetic composite restorations are used to close midline diastema. Crowns can be used to make peg laterals look more natural and esthetic. Bridges or implants are used to replace the missing teeth. The prosthesis will avoid the distal movement of central incisors leading to relapse.

Conclusion:

So considering different uneventful dental development, it is concluded that midline diastema is treatable and hence should not be worried about. If diastema is larger than 2.7 millimeters (mm) even after the eruption of permanent lateral incisors, then orthodontic treatment is necessary. Timing of orthodontic treatment is very important for the achievement of satisfactory results. Elimination of etiologic agents can usually be commenced on diagnosis and after the adequate eruption of central incisors. Treatment is usually postponed until the eruption of permanent canines, but it can be initiated early in certain cases of large diastema. Retention procedure should be according to the size and etiology of midline diastema.

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