Nonextraction orthodontic therapy: posttreatment dental and skeletal stability

To assess the long-term stability of nonextraction orthodontic treatment, the dental cast and cephalometric records of 28 cases were evaluated. Thirty cephalometric and seven cast parameters were examined before treatment, posttreatment, and an average of almost 8 years postretention. Results showed overall long-term stability to be relatively good. Relapse patterns seen were similar in nature, but intermediate in extent, between untreated normals and four first premolar extraction cases. Significant decreases were seen in arch length and intercanine width during the postretention period despite minimal changes during treatment. Incisor irregularly increased slightly postretention; intermolar width, overjet, and overbite displayed considerable long-term stability. Mandibular incisor mesiodistal and faciolingual dimensions were not associated with either pretreatment or posttreatment incisor crowding. Class II malocclusions with large ANB values and shorter mandibular lengths showed increased incisor irregularity, shorter arch lengths, and deeper overbites at the postretention stage, suggesting that the amount and direction of facial growth may have been partially responsible for maturational changes seen during the postretention period.     

Posttreatment and postretention changes following orthodontic therapy.

This investigation was performed to determine the changes which occurred in treated orthodontic cases out of retention. The material consisted of 103 cases, of which 74 cases were treated nonextraction and 29 were treated with the extraction of four first premolars. The treatment was accomplished by the full-banded edgewise bioprogressive technique. Five measurements were taken: intercanine, inter-first premolar, intersecond premolar and inter-first molar widths, and incisor to molar distance. The measurements were made on the mandibular arch of the pretreatment, posttreatment, and prostretention casts. The postretention model was obtained a minimum of one year after all retaining devices were removed with an average of 5.2 years. The following conclusions were drawn from the changes in dimensions: 1. The intercanine width was expanded during treatment, but had a strong tendency to return to or close to its original pretreatment width in both nonextraction and extraction cases. 2. The inter-first premolar width showed the greatest treatment increase in width with only a minimal amount of postretention decrease. 3. The second premolar width for nonextraction cases showed a significant amount of increase with a slight tendency for postretention decrease. 4. The second premolar width for extraction cases showed a decrease with treatment and a slight continued decrease postretention. 5. The intermolar width of nonextraction cases showed a significant increase in width with treatment. The extraction cases showed a significant decrease with treatment. However, there were no changes in either extraction or nonextraction cases postretention. 6. The incisor to molar distance decreased with treatment and had a slight tendency to continue to decrease postretention.     

Relapse in Angle Class II Division 1 Malocclusion treated by tandem mechanics without extraction of permanent teeth: A retrospective analysis.

Ideal orthodontic treatment should achieve long-term stability of the occlusion. The mandibular incisor segment has been described as the segment that is most likely to exhibit relapse after treatment and retention. Therefore, relapse of this is a challenge that clinicians need to address. The purpose of this study is to evaluate the amount of relapse that may occur in Angle Class II Division 1 patients, treated orthodontically with tandem mechanics. All cases in this study were treated without extraction of permanent teeth, and the patients were followed for at least 2 years after the end of the retention phase of treatment. Six predictors were investigated at pretreatment, posttreatment, and postretention periods. A synopsis of this study shows the correction of lower incisor crowding as measured by the irregularity index was stable over 5.2 years of postretention follow-up; but longer follow-up time revealed increased relapse of incisor irregularity. Intermolar width increased during treatment and remained stable in the follow-up period. Overjet and overbite corrections and changes in the lower incisor to mandibular plane angle were also stable in the follow-up period. In addition, the amounts of overjet correction and loss of expansion of intercanine distance after treatment were associated with increased irregularity index in the follow-up period. It appears the discrepancies between this and previously published works are sufficiently dramatic that the whole question of treatment philosophy and long-term stability may need to be reevaluated.     

Stability and relapse of mandibular anterior alignment: a cephalometric appraisal of first-premolar-extraction cases treated by traditional edgewise orthodontics

Assessment at least 10 years postretention of fifty-four cases previously treated in the permanent-dentition stage with first-premolar extractions, traditional edgewise mechanotherapy, and retention revealed considerable variation among patients. The long-term response to mandibular anterior alignment was unpredictable; no cephalometric parameters, such as maxillary and mandibular incisor proclination, horizontal and vertical growth amounts, mandibular plane angle, etc., were useful in establishing a prognosis. Few associations of value were found between cephalometric parameters and dental-cast measurements, such as overbite, arch length, intercanine width, and overjet. Only a slight tendency was found for incisor inclination to return toward the pretreatment value during the postretention period. It was possible to predict, on the basis of an analysis of pre- and posttreatment cephalometric records, those cases which had greater than 4 mm deepening of overbite postretention as well as those cases which had decreases of 3 mm or more in arch-length postretention. The practical use of these predictions were of limited clinical value, however.     

Anterior open-bite malocclusion: a longitudinal 10-year postretention evaluation of orthodontically treated patients

Long-term response of the anterior open-bite malocclusion was evaluated in forty-one white subjects who had undergone orthodontic treatment and were out of retention a minimum of 9 years 6 months. The purpose of the study was threefold: (1) to make cephalometric comparisons between a sample of open-bite patients and a sample with normal cephalometric standards, (2) to evaluate treatment and posttreatment changes that occurred in treated open-bite patients, and (3) to search for predictors and associations of value. Changes occurring across time in the open-bite patients were analyzed by computer means using pretreatment, posttreatment, and long-term cephalometric radiographs and dental casts. An analysis of subgroups was reviewed to compare dentoalveolar and skeletal relationships of both stable and relapse groups. More than 35% of the treated open-bite patients demonstrated a postretention open bite of 3 mm or more, with the relapse subgroup demonstrating across-time, less mandibular anterior dental height, less upper anterior facial height, greater lower anterior facial height, and less posterior facial height. Neither the magnitude of pretreatment open bite, mandibular plane angle, nor any other single parameter of dentofacial form proved to be a reliable predictor of posttreatment stability.     

Postretention changes in mandibular crowding: a review of the literature.

Posttreatment stability is one of the challenges facing orthodontists today. Relapse of the mandibular anterior segment during the postretention period is perhaps the most predictable and frustrating of all orthodontic relapses. This type of relapse is sometimes erroneously construed as a sign of inappropriate treatment or evidence of misdiagnosis or incorrect mechanics. This article reviews mandibular incisor postretention stability outcomes in the setting of different treatment techniques and different ages of beginning orthodontic treatment. Mandibular incisor relapse is almost inevitable, regardless of orthodontic techniques and timing of orthodontic treatment. However, mandibular incisor relapse might be reduced when palatal expansion is combined with prolonged retention.     

A retrospective study of Angle Class I malocclusions treated orthodontically without extractions using two palatal expansion methods.

The correction and relapse of mandibular anterior crowding was evaluated in a population of 58 patients with Angle Class I malocclusion who were treated orthodontically without extraction of permanent teeth. The subjects were retrospectively evaluated from records taken before treatment, posttreatment, and postretention. The postretention period averaged 8 years (minimum of 4 and maximum of 20 years). All cases in Groups A and B were given orthopedic treatment to develop the maxillary apical base in the transverse and anteroposterior planes. Group A was treated with expansion of the inner bow of the face bow appliance (Kloehn), and Group B was treated with the Haas palatal expansion appliance. Both groups were then treated orthodontically with tandem mechanics. The response variables measured were: overbite, overjet, intercanine distance, intermolar distance, and irregularity index. Study groups A and B were not significantly different for subject age, retention, or postretention time. Moreover, the groups did not show significant difference for any of the response variables before treatment. However, there was a statistically significant difference in the treatment times (P =.0133). A statistically significant treatment effect was observed for most response variables in the groups. Overbite, overjet, and irregularity index were significantly reduced, intermolar distance was significantly increased, and intercanine distance showed no significant change in Groups A and B. In the postretention period, there was a tendency for variables to change slightly toward their before treatment values but no compromise of orthodontic correction was noted. The irregularity index in Group A was corrected from 4.8 to 1.1 mm and remained at 1.1 mm in the postretention period. The irregularity index in Group B was corrected from 5.1 to 1.2 mm (P =.0001) and changed slightly from 1. 2 to 1.7 mm (P =.0540) in the postretention period. We concluded that mandibular incisors tended to become more crowded postretention. However, in contrast to previous reports, we calculate this relapse to be small. Neither before treatment nor posttreatment variables were predictive of relapse.     

Mandibular incisor extraction--postretention evaluation of stability and relapse.

Pretreatment, posttreatment and 10-year postretention dental cast and lateral cephalogram records of 42 patients were evaluated. Each patient had undergone edgewise orthodontic treatment following removal of one or two mandibular incisors and various maxillary teeth. Seven of 24 patients (29%) in the single-incisor extraction group and 10 of 18 (56%) patients in the two-incisor extraction group demonstrated unacceptable mandibular incisor alignment at the postretention stage. This result was considerably more favorable than the results of previously reported premolar extraction cases (70% unacceptable alignment at postretention). Intercanine width decreased during treatment and continued to decrease postretention in most cases. Overbite and overjet remained acceptable. No associations could be found to predict the amount of relapse.     

Postretention relapse of mandibular anterior crowding in patients treated without mandibular premolar extraction.

Treatment stability is one of the most important objectives in orthodontics, but, despite decades of research, it is still agreed that the stability of aligned teeth is variable and largely unpredictable. This study aimed to evaluate the relapse of mandibular anterior crowding in patients treated without mandibular premolar extraction. The sample comprised 40 patients of both sexes with Class I or II malocclusions who received nonextraction treatment in the mandibular arch with edgewise mechanics. Lateral cephalograms and dental casts of each patient were obtained at pretreament, posttreatment, and 5 years postretention. Relapse of mandibular anterior crowding was assessed, and associations between this relapse and other clinical factors were also investigated. Mandibular anterior crowding was measured by the Little irregularity index, and the data were evaluated by the Mann-Whitney test. The mean relapse of mandibular anterior crowding was 1.95 mm (26.54%) over the long term. No clinical factor studied was predictive of crowding relapse in the long term.     

Cephalometric appraisal of posttreatment vertical changes in adult orthodontic patients.

The purpose of this study was to evaluate vertical facial changes in adult orthodontic patients and to evaluate the stability of these changes. Thirty-three patients (8 males and 25 females) were examined. The patients had been treated with full fixed edgewise appliance mechanics and exhibited at least 1.0 degrees of clockwise rotation of the mandible during treatment. Mandibular rotation was determined by the angular change in the Y-axis to the Frankfort plane. Twelve angular and 14 linear skeletal and dental measurements and 3 skeletal ratios were derived from pretreatment (T1), posttreatment (T2), and postretention (T3) cephalometric radiographs. Paired t tests were used to compare vertical changes that occurred as a result of orthodontic treatment and their stability or relapse tendency during the retention and postretention periods. Twenty-five percent (P <.001) of the opening rotation of the mandible recovered during the posttreatment period, resulting in a significant overall rotation that was maintained. Both treatment and posttreatment changes in the Y-axis angle showed a high correlation with the horizontal position of pogonion (r = -0.797 and -0.889, respectively). Only overjet showed a low correlation between treatment changes and posttreatment changes in the Y-axis angle. Stepwise regression analysis of pretreatment variables and treatment changes failed to predict the behavior of the Y-axis angle change.     

The relationship between the curve of spee,relapse, and the Alexander discipline

Exaggerated curves of Spee are frequently observed in dental malocclusionsthat present with deep vertical overbites. During orthodontic treatment such excessive curves of Spee are usually leveled and, in most instances, this leveling will result in a reduction of the anterior overbite. The Alexander Discipline provides a good example of modern straight-wire orthodontic techniques that purport an ability to treat abnormal variations in the depth of the occlusal plane. The records of 31 randomly selected patients treated by nonextraction with the Alexander Discipline were studied. The results show that the Alexander Discipline levels the curve of Spee in Class II, Division I deep-bite cases and that when relapse occurs, the curve of Spee returns to a lesser extent than was present before orthodontic treatment. With the Alexander Discipline, a pretreatment curve of Spee that is not completely level posttreatment has a slightly higher incidence and magnitude of relapse than a pretreatment curve of Spee that is completely level posttreatment. This study indicated that, based on the pretreatment curve of Spee, there is no ability to predict relapse in mandibular intercanine width, overbite, overjet, mandibular incisor irregularity, and arch length in Class II, Division I deep-bite cases treated with the Alexander Discipline.     

Mandibular growth rotation effects on postretention stability of mandibular incisor alignment

OBJECTIVE: To test the hypotheses that pronounced forward and backward mandibular growth rotation may be risk factors for postretention relapse of mandibular incisor alignment, and that morphologic parameters at adolescence may be predictive of the remaining type of mandibular growth. MATERIALS AND METHODS: Cephalograms and study models were made before (T1) and after (T2) active treatment and at a minimum of 10 years postretention (T3) of three groups of orthodontic patients with acceptable occlusion at the time of appliance removal. The groups were short facial height (n = 46), angle between the sella-nasion line and the mandibular plane (SN/MP) or= 38 degrees at T2. RESULTS: The groups were similar regarding age at T2, gender ratio, incisor irregularity (IRI), intercanine (3-3) width at T1, change of 3-3 width from T1 to T2, and time from T2 to T3 (P > .05). IRI increased in all groups from T2 to T3 (P < .05), but there were not any intergroup differences in this increase (P > .05). Minor differences were detected among the groups in mandibular growth rotation from T2 to T3. Males experienced more forward rotation than females (P < .001) and more increase in IRI from T2 to T3 (P < .01). Male gender, T1-T2 increase in 3-3 width, and T2-T3 reduction in 3-3 width were included in the model explaining T2-T3 increase in IRI. CONCLUSION: High-angled and low-angled facial patterns at time of appliance removal are not associated with increased risk of postretention relapse of mandibular incisor malalignment, and in adolescent orthodontic patients are poor predictors of type of posttreatment growth.     

Long-term stability of Class I premolar extraction treatment.

This study evaluates Class I, 4-premolar-extraction patients who were treated with the edgewise appliance by 1 practitioner, according to the philosophy of Tweed, and who had been out of retention a minimum of 5 years. The sample includes 32 patients, who started treatment at an average age of 12.8 years and who were examined a mean of 15 years posttreatment (11.7 years postretention). Cephalometric and model analyses were conducted to evaluate treatment and posttreatment tooth movements. The results showed that irregularity, as measured by the irregularity index, decreased 5.3 mm during treatment and increased 0.7 mm (SD 1.1 mm) during the posttreatment period. Eighty percent of the patients had satisfactory (<3.5 mm) mandibular incisor alignment over 10 years postretention, and none was in the severe category (>6.5 mm). Mandibular intercanine width increased (1.7 mm) during treatment, whereas intermolar width decreased (-2.1 mm). Maxillary molar widths remained unchanged posttreatment, and mandibular intercanine width decreased 1.4 mm from immediately posttreatment to postretention. Arch lengths decreased during treatment because of molar protraction and incisor retraction. Mandibular arch length continued to decrease posttreatment (-1.4 mm) because of mesial molar movement rather than distal incisor movement. Satisfactory long-term results can be achieved for most Class I, 4-premolar-extraction patients for whom evidence-based treatment objectives-including minimal alteration of the mandibular arch form and the retraction and uprighting or maintenance of mandibular incisors in their original position-have been met.     

Expansion of the lower arch concurrent with rapid maxillary expansion

The effect of rapid maxillary expansion on the mandibular intercanine and intermolar widths during treatment and its stability after retention was studied. In addition, the relationships between the interarch change and the facial types and ages of the subjects of the sample were evaluated. The sample consisted of 17 cases for the study of intercanine width, and 22 nonextraction cases for the study of the intermolar width. Initial, final, at least 2-years postretention models, and initial lateral cephalograms were analyzed. Treatment and postretention changes for the intercanine width and the mesial and distal intermolar widths were calculated and tested for significance. Mean expansions of the intercanine width of 1.1 mm and of the intermolar width of 2.8 mm postretention were found to be statistically significant. There were no correlations found between the amount of increase in arch width and the facial types and ages of the subjects.     

Stability and relapse of mandibular anterior alignment: University of Washington studies

For more than 40 years, research in the Department of Orthodontics, University of Washington (Seattle, WA) has focused on a growing collection of more than 800 sets of patient records to assess stability and relapse of orthodontic treatment. All patients had completed treatment a decade or more before the last set of data. Evaluation of treated premolar extraction patients, treated lower incisor extraction patients, treated non-extraction cases with generalized spacing, patients treated with arch enlargement strategies, and untreated normals showed similar physiologic changes: (1) Arch length decreases after orthodontic treatment. (2) Arch width measured across the mandibular canine teeth typically reduces posttreatment, whether or not the case was expanded during treatment. (3) Mandibular anterior crowding during the posttreatment phase is a continuing phenomenon well into the 20-to-40 years age bracket and likely beyond. (4) Third molar absence or presence, impacted or fully erupted, seems to have little effect on the occurrence or degree of relapse. (5) The degree of post-retention anterior crowding is both unpredictable and variable and no pretreatment variables either from clinical findings, casts, or cephalometric radiographs before or after treatment seem to be useful predictors.     

Changes in the curve of Spee with treatment and at 2 years posttreatment.

The purposes of this study were to determine pretreatment skeletal and dental patterns related to curve of Spee depth, evaluate changes in the curve of Spee with treatment and the effects on dentofacial structures, and determine factors associated with the stability of the curve of Spee after treatment. Lateral cephalograms and dental casts were evaluated for 24 white male and 26 white female patients at pretreatment, posttreatment, and at least 2 years postretention. All patients had mandibular permanent second molars and premolars erupted and in occlusion. The following variables were correlated with increased pretreatment curve of Spee depth: low Frankfort-mandibular plane angle, deep overbite, increased overjet, and Class II molar malocclusion. No significant differences were found in pretreatment curve depth between male and female patients or between right and left sides. Leveling the curve of Spee was accomplished by uprighting the molars, extruding the premolars, and intruding or flaring the incisors. Extraction and nonextraction cases demonstrated no significant differences in the amount of curve relapse. Increased curve relapse was correlated with postretention increases in overbite, irregularity index, and patients given removable retainers. Overall, the curve of Spee was relatively stable after treatment, with only a 16% relapse of the leveled curve.     

The mandibular plane angle in activator treatment.

The long-term results of activator treatment were investigated in 15 subjects with a small and 13 subject with a large pretreatment mandibular plane angle. The results of the investigation revealed the following: 1. Activator treatment resulted in a general improvement in the sagittal and vertical incisor relationship in both large and small angle cases. 2. Overjet relapse was more frequent and overbite relapse less frequent in large angle cases than in small angle cases. 3. During the period before treatment follow-up examination the frequency of patients with open bite increased in the large angle group and decreased in the small angle group. 4. The mandibular intercanine arch width was smaller and the frequency of crowding in the mandibular incisor segment was higher in the large angle group than in the small angle group. 5. A large pretreatment mandibular plane angle, per se, was not a primary factor in treatment failure. However, an unfavourable mandibular growth in combination with an atypical tongue function seemed to be the main reason for the relapse found in the large angle subjects.     

The stability of the arch-expansion effects of Fr?nkel appliance therapy

To assess the long-term stability of the arch expansion effects of the functional regulator, mandibular dental casts were evaluated for treatment and postretention changes in intercanine width, width between first premolars, width between second premolars, intermolar width, incisor irregularity, and arch length. This study was comprised of 11 cases that were treated with the Fr?nkel appliance (mean = 27 mo.) and were and average of 4 years and 4 months out of active treatment. Results showed overall stability to be good, with some variability present in individual responses. Intercanine width, width of first premolars, width of second premolars, and intermolar width all demonstrated maintenance of treatment increases. Correction of incisor irregularity displayed better stability than has been reported in other stability studies. Arch length decreased with treatment and continued to decrease during the postretention period, although to a lesser extent than has been previously reported. The results of this study support the statements of Fr?nkel concerning the stability of this type of arch expansion.     

Evaluation of posttreatment changes in Class II Division 1 patients after nonextraction orthodontic treatment: cephalometric and model analysis.

BACKGROUND: The aim of this retrospective study was to evaluate changes in patients with Class II Division 1 malocclusions treated with cervical headgear and full fixed orthodontic appliances and without extractions. METHODS: Lateral cephalograms and dental casts of 18 patients were obtained at the beginning and the end of treatment and at the postretention period. Pretreatment records were taken at 11.9 +/- 2.6 years, and the mean treatment time was 2.8 +/- 1.2 years. All patients were asked to use maxillary and mandibular Hawley retainers for 1 year. The average postretention interval was 5.3 years. RESULTS: The assessment of cephalometric findings showed that maxillary growth was restricted; maxillary incisor inclination, overjet, and overbite were decreased; the mandibular incisors were proclined; and a slight mandibular posterior rotation occurred at the end of treatment. At the postretention period, the maxilla remained stable, the mandible moved anteriorly, and the overjet increased slightly (1.25 mm, P < .01). The dental cast changes indicated that both maxillary and mandibular irregularity index values decreased significantly during treatment but increased after 5 years. Mandibular intercanine width decreased 0.47 mm ( P < .01) during the postretention period. CONCLUSIONS: The redirection of maxillary growth remained stable in patients with Class II malocclusions treated with cervical headgear and fixed orthodontic appliances and without extractions, but treatment-induced mandibular rotations tended to return to their original patterns. Various dental changes occurred during the postretention period.     

Postretention Changes in Canine Position Results of a Long-Term Follow-Up

The aim of the present study was to evaluate sagittal, vertical and transverse changes in canine position and a possible correlation with relapse of lower anterior crowding. From a sample with a long-term follow-up of 15.7 +/- 4.4 years after treatment, patients with a full dentition were enrolled in the study. Post-treatment and long-term follow-up casts of 117 patients were measured and statistically analyzed. A decrease in intercanine width was found between post-treatment and long-term follow-up records, with more lingual inclination of the mandibular canine axis in the transverse plane. There was a significant correlation between maxillary and mandibular canine inclination. Concomitant changes were an increase in lower anterior crowding and a decrease in mandibular intercanine width. Relapse of anterior crowding has a multifactorial etiology. The results of this study suggest a possible influence of the canines. Functional causes in particular might have a profound influence and should be considered during treatment planning.