**5. Stability of diastema treatment**

Concern over the stability of results obtained with treatment has existed for more than a century [37].

Riedel [38], in reviewing the problem of containment in the literature, proposed nine theorems that should be considered for greater stability of treatment results. In the first, the author mentioned that orthodontically moved teeth tend to return to their original positions. In Theorem 3, it is reported that the etiological factors of malocclusion should be eliminated for greater stability. Theorem 6 states that the bone and adjacent tissues should have a time for reorganization around the new tooth position, so some type of holding device should be used. And finally, in Theorem 9, it is ensured that the higher the tooth movement, the less recurrence.

septal cleft, root parallelism, anterior maxillary spacing, periodontal bone loss and heredity. Pre- and posttreatment data were obtained from the available documentation (models, radiographs, photographs, and clinical records). Post-retention data were collected from a follow-up visit of 37 patients (group A) and a telephone interview of 59 patients (group B). The incidence was 49% in the total, and 46% in group A, considering the patients with the diastema observed, or already portrayed by restoration or orthodontically, and still those who make continuous use of the retention by perceiving a tendency to reopen of space. However, in group A, the space in patients with recurrence ranged from 0.3 to 0.6 mm, but the mean was 0.1 mm. Logistic regression analysis revealed that the initial width of the diastema and the family tendency were risk factors for relapse. Although patients with abnormal braking had earlier initial diameters than those with a normal brake, no association was found between recurrence and the presence of an abnormal or crevice brake in the intermaxillary bone crest. The mobility of the upper incisors was the only parameter found in the postretention period

Stability of Diastemas Closure after Orthodontic Treatment

http://dx.doi.org/10.5772/intechopen.82480

103

Surbeck et al. [41] evaluated the influence of occlusal changes on the stability in the anterior region of the maxilla. The sample was selected from study models for the posttreatment stage and was divided into three groups: (1) with anterosuperior spaces in this phase; (2) with crowding in the anterosuperior region; and (3) with perfect alignment. In group 1, it was found that the presence of spaces before treatment, as well as at the end of the treatment, increases the risk of increased spaces after treatment is finished. The authors suggest that the contention strategy should be altered according to the presence of spaces before treatment and their severity. Also, an association was observed between the increase of the spaces in the post-containment period and the reduction of the intercanine distance during the treatment. It was also found that reopening of spaces was associated with increased arch length and

Some authors [15, 21] agree that orthodontic closure of diastemas caused by an abnormal labial frenulum, without subsequent brake removal surgery, greatly increases the frequency

Edwards [15] evaluated the relation of the abnormal labial frenulum with both the etiology of diastema and the stability of its treatment. In this study, the author concluded that frenectomy had a great contribution to increase the stability of the orthodontic treatment of the median diastema and commented, citing that the upper labial frenulum is one of the most relevant

On the contrary, Shashua and Ärtun [28] did not consider the central labial cleft lip and fissure in the central interincisive bone crest as risk factors for diastema recurrence, after evaluation of diastema relapse 4–9 years after the end of treatment. The authors [28] observed that the presence of the abnormal brake at the beginning of the treatment influenced the initial width of diastema. However, they emphasized that this type of brake can remodel spontaneously

that could be associated with the reopening of the space.

intercanine and intermolar distances in the posttreatment period.

factors for the reopening of orthodontically closed diastema.

of relapse in the post-retention period.

with the closing of the space.

**5.1. The upper lip frenulum and its relation to the recurrence of diastema**

The work of Ormiston et al. [39] observed that the greater the severity of malocclusion, the greater the recurrence. This means that the greater the severity of malocclusion, the greater the movement required and the greater the relapse. In this way, they oppose Riedel's Theorem 9 [38].

There are few scientific studies that evaluate the diastema recurrence after orthodontic closure [15, 28, 40, 41].

Orthodontic corrections in the growth and eruption phases of the teeth are considered more stable by some authors. According to Reitan [37], there will be little or no recurrence after orthodontic movement of an erupting tooth due to the fact that the supporting tissues are in a proliferation stage as a result of the eruption process. New fibers will be formed as the root develops, and these new fibers will help maintain the new tooth position.

Almeida et al. [16] have speculated that the closure of diastema in the mixed denture phase is more stable than if treated in the permanent denture. Therefore, it does not require definitive containment, as long as the habit is removed and, in case of interincisive gingival hypertrophy, surgical correction is performed before removal of the device.

Edwards [15] cited several factors responsible for the reopening of the diastema: incorrect axial inclination of the central incisor roots, tooth size discrepancies, deleterious habits, deleterious occlusal patterns, such as displacement from centric relation to maximal habitual intercuspation or other mandible position, which generate lateral forces on the central incisors, anatomy of the teeth (wider cervical region than the incisal region), and possibly some muscular imbalance in the oral cavity. But in addition to these, the labial frenulum, along with associated tissues, is cited as the most frequent etiological factor in relapsing interincisal diastemas.

The influence of muscular imbalances on the maintenance of bad dental positions varies according to three factors: duration, frequency, and intensity. Studies [10, 22] emphasized that when an etiological factor, such as atypical lingual pressure, cannot be eliminated, it is very difficult to keep the space closed, without the use of permanent retention, especially in adult patients. Attia [10] mentioned that in these patients, the chances of success of improving the lingual posture with only exercises are minimal and indicates the glossectomy.

Shashua and Ärtun [28] evaluated the proportion of diastema recurrence and the possible variables that may have contributed to this recurrence in a sample of 96 patients 4–9 years after the end of treatment. Diastemas varied from 0.5 to 5.6 mm in the pre-treatment stage. The following variables were analyzed: initial diastema size, tooth size discrepancy, overbite, upper incisor inclination, maxillary incisor mobility, labial frenulum, intermaxillary septal cleft, root parallelism, anterior maxillary spacing, periodontal bone loss and heredity. Pre- and posttreatment data were obtained from the available documentation (models, radiographs, photographs, and clinical records). Post-retention data were collected from a follow-up visit of 37 patients (group A) and a telephone interview of 59 patients (group B). The incidence was 49% in the total, and 46% in group A, considering the patients with the diastema observed, or already portrayed by restoration or orthodontically, and still those who make continuous use of the retention by perceiving a tendency to reopen of space. However, in group A, the space in patients with recurrence ranged from 0.3 to 0.6 mm, but the mean was 0.1 mm. Logistic regression analysis revealed that the initial width of the diastema and the family tendency were risk factors for relapse. Although patients with abnormal braking had earlier initial diameters than those with a normal brake, no association was found between recurrence and the presence of an abnormal or crevice brake in the intermaxillary bone crest. The mobility of the upper incisors was the only parameter found in the postretention period that could be associated with the reopening of the space.

Riedel [38], in reviewing the problem of containment in the literature, proposed nine theorems that should be considered for greater stability of treatment results. In the first, the author mentioned that orthodontically moved teeth tend to return to their original positions. In Theorem 3, it is reported that the etiological factors of malocclusion should be eliminated for greater stability. Theorem 6 states that the bone and adjacent tissues should have a time for reorganization around the new tooth position, so some type of holding device should be used. And finally, in Theorem 9, it is ensured that the higher the tooth movement, the less recurrence.

The work of Ormiston et al. [39] observed that the greater the severity of malocclusion, the greater the recurrence. This means that the greater the severity of malocclusion, the greater the movement required and the greater the relapse. In this way, they oppose Riedel's Theorem 9 [38]. There are few scientific studies that evaluate the diastema recurrence after orthodontic clo-

Orthodontic corrections in the growth and eruption phases of the teeth are considered more stable by some authors. According to Reitan [37], there will be little or no recurrence after orthodontic movement of an erupting tooth due to the fact that the supporting tissues are in a proliferation stage as a result of the eruption process. New fibers will be formed as the root

Almeida et al. [16] have speculated that the closure of diastema in the mixed denture phase is more stable than if treated in the permanent denture. Therefore, it does not require definitive containment, as long as the habit is removed and, in case of interincisive gingival hypertro-

Edwards [15] cited several factors responsible for the reopening of the diastema: incorrect axial inclination of the central incisor roots, tooth size discrepancies, deleterious habits, deleterious occlusal patterns, such as displacement from centric relation to maximal habitual intercuspation or other mandible position, which generate lateral forces on the central incisors, anatomy of the teeth (wider cervical region than the incisal region), and possibly some muscular imbalance in the oral cavity. But in addition to these, the labial frenulum, along with associated tissues, is cited as the most frequent etiological factor in relapsing interinci-

The influence of muscular imbalances on the maintenance of bad dental positions varies according to three factors: duration, frequency, and intensity. Studies [10, 22] emphasized that when an etiological factor, such as atypical lingual pressure, cannot be eliminated, it is very difficult to keep the space closed, without the use of permanent retention, especially in adult patients. Attia [10] mentioned that in these patients, the chances of success of improving

Shashua and Ärtun [28] evaluated the proportion of diastema recurrence and the possible variables that may have contributed to this recurrence in a sample of 96 patients 4–9 years after the end of treatment. Diastemas varied from 0.5 to 5.6 mm in the pre-treatment stage. The following variables were analyzed: initial diastema size, tooth size discrepancy, overbite, upper incisor inclination, maxillary incisor mobility, labial frenulum, intermaxillary

the lingual posture with only exercises are minimal and indicates the glossectomy.

develops, and these new fibers will help maintain the new tooth position.

phy, surgical correction is performed before removal of the device.

sure [15, 28, 40, 41].

102 Current Approaches in Orthodontics

sal diastemas.

Surbeck et al. [41] evaluated the influence of occlusal changes on the stability in the anterior region of the maxilla. The sample was selected from study models for the posttreatment stage and was divided into three groups: (1) with anterosuperior spaces in this phase; (2) with crowding in the anterosuperior region; and (3) with perfect alignment. In group 1, it was found that the presence of spaces before treatment, as well as at the end of the treatment, increases the risk of increased spaces after treatment is finished. The authors suggest that the contention strategy should be altered according to the presence of spaces before treatment and their severity. Also, an association was observed between the increase of the spaces in the post-containment period and the reduction of the intercanine distance during the treatment. It was also found that reopening of spaces was associated with increased arch length and intercanine and intermolar distances in the posttreatment period.
