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.     

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.     

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.     

Age-Related Long-Term Posttreatment Occlusal and Arch Changes

Objective:To evaluate differences in long-term postretention changes between adolescents and adults.Materials and Methods:The sample included 96 subjects, 51 adolescents and 45 adults (14.2 ± 0.8 and 21.5 ± 6.8 years of age, respectively, at the end of treatment) retained for 3 years and followed approximately 16 years post treatment, who were randomly selected from two private practices. Prior to treatment, 38 and 58 had Class I and Class II malocclusions, respectively.Results:With the exception of adult midlines, all of the occlusal variables (overjet [0.50–0.77 mm], overbite [0.85–0.95 mm], the maxillary incisor irregularity [0.69–0.80 mm], the mandibular incisor irregularity [0.85–1.50 mm] and the PAR score [0.86–1.92 points]) showed significant increases over time. Adolescents consistently showed greater increases of the occlusal variables than adults, with mandibular incisor irregularity and the PAR index attaining statistically significant (P < .05) levels. Arch length and mandibular intercanine width showed statistically significant decreases over time in both groups; maxillary intercanine and intermolar widths did not change significantly. Overjet increased significantly more in Class II patients than in Class I patients, whereas Class I patients showed significantly greater decreases in mandibular intermolar width than Class II patients.Conclusions:Over the 16-year posttreatment period, adolescents showed significantly greater increases in mandibular incisor irregularity, and the PAR index than adults. Treated Class I patients demonstrated less increase in overjet and greater decreases in mandibular intermolar width than Class II patients.     

Effects of extraction and nonextraction treatment on class I and class II subjects

This study aims to examine the profile as well as the dentoalveolar and skeletal effects of extraction or nonextraction treatment in a wide range of patients including Class I and Class II, division 1 cases. Results achieved with extraction and nonextraction modalities have also been compared. The study was performed on pretreatment and posttreatment lateral cephalograms of 87 orthodontic patients. There were no significant differences between the pretreatment values of extraction and nonextraction Class I groups, whereas SN-GoGn (degrees), maxillary incisor to A-Po (degrees), mandibular incisor to A-Po (mm), Co-Gn (mm), overjet (mm), and overbite (mm) measurements of extraction Class II group were significantly higher before the treatment. After treatment, these differences were eliminated in the Class II group; however, incisors were significantly protruded in both nonextraction groups. No other differences in profile or lip position were found between the extraction and nonextraction groups. The results of this study indicate that in successfully treated cases, whether by extraction or nonextraction, the same soft and hard tissue profile posttreatment end points were reached except for the incisor positioning, which is rather easier to anticipate than profile and soft tissue changes. The simple statement that extraction means a more retrusive or dished-in profile seems to be unacceptable. It seems that a more thorough assessment and investigation including pretreatment extent of crowding and factors related to anchorage, soft tissue thickness, and strain should be carried out.     

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.     

Overbite and overjet correction in a Class II, division 1 sample treated with Edgewise therapy

The purpose of this study was to compare the effect of overjet and overbite correction in non-extraction and extraction therapy in a sample of Class II malocclusions treated with the Edgewise appliance. The subjects were 20 children treated without extraction and 20 children treated with extraction of the four first premolars. During the post-treatment period a relapse of overjet and overbite occurred in both groups. However, there was a beneficial net effect of overjet and overbite correction in both groups with no significant difference between the two groups. The study showed that mandibular intercanine width, space conditions in the lower jaw and mandibular incisor position were important factors in treatment planning.     

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.     

The relationship between the incisor position and lingual surface morphology in normal occlusion

This study aimed to investigate the relationship between the morphological characteristics of maxillary incisors and the anterior occlusion. The study materials comprised dental casts and lateral cephalograms of 26 modern Mongolian females with Angle Class I normal occlusion (mean age, 21 years 5 months). Computed tomography (CT) images of the dental casts were taken with an X-ray micro-CT system (SMX-100CT, Shimadzu, Kyoto Japan). The thickness of the marginal ridges and incisal edges, and the overjet and overbite, was measured on the three-dimensional images of the dental casts. On the lateral cephalogram, maxillary incisor to sella–nasion plane angle (U1 to SN angle), maxillary incisor to nasion-point A plane distance (U1 to NA distance), mandibular incisor to nasion-point B plane distance (L1 to NB distance), incisor mandibular plane angle, and interincisal angle were measured by tracing the left incisors of the maxilla and mandible. Spearman’s single rank correlation coefficients were used to investigate any correlation between measurement items for each maxillary incisor. The thickness of the marginal ridges and incisal edges was positively correlated with the overbite. The thickness of the incisal edges was positively correlated with the irregularity index of the maxilla. There were significant negative correlations between overbite and U1 to SN angle, U1 to NA distance, and L1 to NB distance. Significant positive correlations were noted between the overbite and the overjet. In conclusion, there was no strong relationship between the morphological characteristics of maxillary incisors and the anterior occlusion.     

Predictors of outcome among patients with class II division 1 malocclusion treated with fixed appliances in the permanent dentition.

This retrospective study investigated the outcomes achieved in 212 consecutively completed patients with Class II Division 1 malocclusion (overjet > 6 mm). All patients were treated in the permanent dentition with upper and lower fixed appliances. A composite outcome measure was used to identify those cases with an excellent outcome (posttreatment PAR 相似文献   

The effectiveness and long-term stability of overbite correction with incisor intrusion mechanics.

BACKGROUND: Correction of deep overbite with subsequent achievement of long-term stability is difficult. The purpose of this study was to investigate the effectiveness and long-term stability of overbite correction with incisor intrusion mechanics. METHODS: The treated group consisted of 25 subjects (13 female, 12 male) with deep overbite of at least 4 mm (mean overbite, 5.9 mm). The orthodontic treatment was initiated in the late mixed or early permanent dentition, and all patients were treated nonextraction. All patients had lateral cephalometric radiographs taken at pretreatment (T1), posttreatment (T2), and postretention (T3). The treatment included cervical headgear and lever arches to intrude mainly the maxillary incisors and occasionally the mandibular incisors. Premolars were not included in the fixed appliances during the treatment. The untreated group consisted of 25 age- and sex-matched subjects from the Bolton Growth Study. RESULTS: The mechanics used were effective in overbite correction. During the posttreatment period, overbite increased by 0.7 mm. CONCLUSIONS: Although this change was statistically significant, the amount was small and is considered clinically insignificant, given the severity of the overbite pretreatment. Furthermore, a net overbite correction (T3-T1) of 3.3 mm and postretention overbite on 2.6 mm is an excellent clinical outcome.     

个别下切牙先天缺失症临床矫治的研究

目的 :探讨先天缺失下切牙各种错牙合畸形类型和达到个别正常牙合的方法。方法 :选取 10例完成正畸治疗的各类个别下切牙先天缺失的错牙合畸形患者 ,男 3例 ,女 7例 ,平均年龄 15.4岁 ,分别测量治疗前后的模型和头颅侧位片 ,调整颌位和牙位 ,通过Bolton指数指导 ,采用片切、拔牙、倾斜牙轴达到正常的前牙覆牙合覆盖。结果 :10例患者都达到了后牙尖窝交错咬合 ,前牙覆牙合覆盖正常 ,尖牙间宽度不变或减少。结论 :有下切牙先天缺失的错牙合畸形 ,通过颌位结合牙位的调整 ,都能达到个别正常牙合的功能和美观的效果     

上颌快速扩弓联合固定矫治器治疗的稳定性研究

目的 观察患者接受上颌快速扩弓联合直丝弓矫治器治疗后覆牙合、覆盖及上牙弓宽度的变化。方法 选择2003年2月—2008年1月于青岛市口腔医院进行治疗的患者37例（男19例,女18例）,将患者分为4个不同的时期进行测量（N1:治疗前;N2:进行上颌快速扩弓后;N3:固定治疗后;N4:保持1年后）。分别测量每位患者的上颌尖牙间宽度、前磨牙间宽度、磨牙间宽度,并对前牙覆盖和覆牙合进行测量。患者的平均年龄（11.3±1.4）岁（10.2～15.3岁）。结果 治疗全部结束后、尖牙间宽度、前磨牙间宽度、磨牙间宽度、覆盖、覆牙合分别增加（2.6±2.3）mm、（3.7±2.1）mm、（5.2±2.5）mm、（0.3±0.6）mm、（-0.1±1.6）mm,患者复发率在尖牙宽度为47%,前磨牙间宽度为21％,磨牙间宽度为10%,覆盖复发率为9%,覆牙合为13%。结论 患者经过上颌快速扩弓后,在固定矫治阶段复发明显,保持阶段也有一定程度的复发。 上颌快速扩弓能够减小覆牙合,增加覆盖。     

安氏Ⅱ类2分类青少年不拔牙矫治前后的硬组织变化

目的评价安氏Ⅱ类2分类青少年不拔牙矫治前后硬组织的变化。方法15例安氏Ⅱ类2分类青少年病例，使用直丝弓矫治技术配合上颌平面导板完成不拔牙矫治。对所有病例治疗前后头颅定位侧位片进行描图和手工测量，比较治疗前后硬组织的改变。结果上前牙舌倾得以纠正，Spee曲线整平，前牙覆[牙合]达到正常，SNB角增大，下前牙压低，下后牙升高，下颌骨长度增加。结论安氏Ⅱ类2分类青少年病例，在上颌前牙舌倾纠正后，下颌骨有一定程度的生长，使上下颌骨矢状向的位置关系得以改善。配合使用平导打开咬合，可以有效地纠正前牙深覆[牙合]，整平Spee曲线，取得良好的治疗效果。     

Long-Term Effects of Rapid Maxillary Expansion Followed by Fixed Appliances

Objective:To evaluate the long-term changes in maxillary arch widths, overjet, and overbite in patients who were treated with rapid maxillary expansion (RME) followed by edgewise appliances.Materials and Methods:The material for the study consisted of study casts taken from 41 patients (19 males, 22 females) on four different occasions (before treatment, T1; after RME, T2; after treatment, T3; and during follow-up period, T4). The upper intercanine, interpremolar, and intermolar widths and overjet and overbite were measured on each set of study casts. Mean age of the subjects was 13.2 ± 1.3 years (range, 11.2–16.9 years) at T1, 13.3 ± 1.3 years (range, 11.3–17 years) at T2, 15.5 ± 1.4 years (range, 13.1–18.8 years) at T3, and 20.4 ± 1.6 years (range, 17.9–24.8 years) at T4.Results:The net increase in intercanine width, interpremolar width, intermolar width, overjet, and overbite was 1.4 ± 2.4 mm, 4.6 ± 2.6 mm, 4.3 ± 2.5 mm, 0.1 ± 0.6 mm, and 0.2 ± 0.6 mm, respectively, and the relapse rates were 37% for intercanine width, 19% for interpremolar width, and 17% for intermolar width at the end of the follow-up period.Conclusions:A significant amount of relapse occurred in maxillary arch widths at the postretention assessment, the greatest being in intercanine width. RME significantly decreased overbite and increased overjet, and a statistically significant decrease was observed in both overbite and overjet at the postretention assessment.     

Long-term follow-up of orthodontically treated deep bite patients

The aim of this study was to evaluate the long-term stability of corrected deep bite and mandibular anterior crowding in a sample of 62 subjects (30 patients and 32 controls). The patients began treatment at a mean age of 12.2 years (SD 1.56). The treatment consisted of non-extraction and fixed appliances in 23 subjects and functional appliances in seven. The treatment group was compared with the control group with normal molar occlusion, normal overjet and overbite, no crowding, and without an orthodontic treatment need. The registrations were made on four occasions: before treatment (T1), after treatment (T2), and at two long-term follow-ups (T3 and T4). Four registrations were also made in the control group. All measurements were undertaken on plaster models and lateral cephalograms. Treatment was found to have normalized the overbite and overjet and to have eliminated the space deficiency in the mandibular anterior region. At T4, there was a minor relapse in overbite in the treatment group (mean 0.8 mm). In the control group, the overbite underwent reverse development (bite opening by 0.7 mm) during the same period. The available mandibular incisor space, however, was -0.9 mm in the treatment group and -1.8 mm in the control group. The long-term stability of the treatment results was thus good.     

Correlation between mandibular central incisor proclination and gingival recession during fixed appliance therapy

The purpose of this study was to determine whether proclination of mandibular central incisors during fixed appliance therapy results in gingival recession. Complete records of 67 patients (39 female and 28 male patients; mean age, 16.4 years; age range, 10-45 years) were used in this retrospective case-control study. Using pretreatment and posttreatment lateral cephalograms, the change in mandibular central incisor inclination was measured to divide the patients into an experimental group (proclination) and a control group (no proclination). Changes in clinical crown length were determined from pretreatment and posttreatment study models, and changes in gingival recession were determined from intraoral slides. Eight of the 67 patients exhibited a measurable increase in gingival recession of at least 0.5 mm, and 27 patients had an increase in clinical crown length of at least 0.5 mm. Statistical analyses showed no correlation between mandibular central incisor proclination and gingival recession or clinical crown length. A t-test analysis showed no statistically significant difference in gingival recession or change in clinical crown length between patients whose mandibular central incisors were proclined and those whose incisors were not proclined. Multiple regression analysis demonstrated that age, sex, race, treatment duration, extraction, treatment type, Angle classification, and proclination were not related to gingival recession or change in clinical crown length of mandibular central incisors. We conclude that the degree of proclination of mandibular central incisors during fixed appliance therapy was not correlated to gingival recession in this sample.     

Orthodontic relapse in subjects with varying degrees of anteroposterior and vertical dysplasia.

Fifty seemingly well-treated orthodontic cases were studied by means of pretreatment, posttreatment, and postretention dental casts, lateral cephalograms, and other orthodontic records. The sample was restricted to cases exhibiting anteroposterior and/or vertical dysplasia as revealed by pretreatment dental casts. The sample was divided into a stable group and a relapse group. Each group contained twenty-five cases. A double-blind design was used. The raw data were analyzed by the stepwise discriminant analysis and by the multivariate analysis of variance. On the basis of the results obtained from this study, the following conclusions can be drawn: 1. In seemingly well-treated orthodontic cases, relapse or stability can neither be predicted nor judged from one set of records alone. 2. Relapse or stability of an orthodontic case can be predicted by comparing the posttreatment variables with the pretreatment variables. 3. Relapse or stability of an orthodontic case can be judged by comparing the postretention variables to the posttreatment variables. 4. The PP-GoGn angle and the mandibular intercanine width are the two most important variables associated with orthodontic relapse. 5. Changing the PP-GoGn angle, either by treatment or by growth, was associated with relapse. In other words, changes in the PP-GoGn angle tended to be unstable. This suggests that decreasing the PP-GoGn angle should be avoided. 6. In both the stable and the relapse groups, the mandibular intercanine width decreased postretention. This decrease was associated more with the relapse group than with the stable group. 7. The mandibular intercanine width tended to relapse toward its original pretreatment value. This suggests that, at the end of active treatment, the mandibular intercanine width should be maintained as originally presented. 8. There was no significant interaction between orthodontic relapse (or stability) and Angle Class I and II cases. 9. There was no significant interaction between relapse (or stability), of an orthodontic case, and the sex of the patient. 10. There was no significant interaction between orthodontic relapse (or stability) and whether or not extraction was included as a part of the mechanotherapy. Thus, the pretreatment deep overbite is not necessarily a contraindication to extraction.     

Effect of reverse curve mushroom archwire on lower incisors in adult patients: a prospective study.

This prospective clinical study was undertaken to analyze adult skeletodental changes induced by a reverse curve mushroom archwire during the initial stage of treatment. Lateral cephalograms from before treatment and immediately after bite opening were evaluated from 8 female adult patients who were undergoing lingual orthodontic treatment. Before treatment the patients had a mean overbite of 3.9 mm. Six linear and 5 angular measurements were selected for cephalometric analysis. The mean change in the cephalometric parameters was subjected to paired t-tests to determine whether the change was significant. There was a highly significant overbite reduction (-1.9 mm, P < .001) leaving a postintrusion overbite of 2.0 mm. The lower incisors were intruded 1.5 mm (P < .001) and the lower incisor edge was in an approximately stable sagittal position (L1 to NPg = -0.2 mm, NS). Some lower incisor proclination (L1 to MP = 1.2 degrees) was seen, which was not of significance. The mandibular molars were not significantly extruded. After bite opening the mandibular plane angle was not significantly altered. Consequently, the lower anterior face height was not significantly increased. The results of this study revealed that the use of reverse curve mushroom archwire is capable of intruding the lower incisors with minimal side effects on the posterior teeth.