首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 156 毫秒
1.
OBJECTIVE: To compare the dentofacial characteristics of persons with Class II, Division 1 malocclusion treated with either an extraction or a nonextraction approach. Such comparison might help identify which parameters influence the extraction decision. METHODS: Lateral cephalograms were available on 81 cases of Class II, Division 1 malocclusion, 42 were treated with 4 premolar extractions and 39 were treated with non-extraction. The cephalometric analysis of West China University of Medical Sciences and Model Analysis were used, RESULTS: Patients in the extraction group had larger FMA, FMIA and lower anterior facial height. In the group of extraction, the upper anterior teeth tipped more anteriorly, and the tooth size-arch length discrepancy and the depth of Spee curve were greater significantly. But the saggital discrepancy and soft tissue's profiles had no significant difference between two groups. CONCLUSION: The stability of the triangle of Tweed, the tooth size-arch discrepancy and the depth of Spee curve were the keys to decide weather extraction or not.  相似文献   

2.
Objective:To evaluate the changes in apical base sagittal relationship in Class II treatment with and without premolar extractions.Materials and Methods:Controlled studies evaluating ANB angle changes after Class II Division 1 malocclusion treatment with or without premolar extractions were considered. Electronic databases (PubMed, Embase, Web of Science, Scopus, The Cochrane Library, Lilacs, and Google Scholar) without limitations regarding publication year or language were searched. Risk of bias was assessed with Risk Of Bias in Non-randomized Studies—of Interventions tool of the Cochrane Collaboration. Mean difference (MD) and 95% confidence interval (CI) were calculated from the random-effects meta-analysis. Subgroup and sensitivity analyses were also performed.Results:Twenty-five studies satisfied the inclusion criteria and were included in the qualitative synthesis. Eleven nonextraction and only one extraction Class II treatment studies presented untreated Class II control group. Therefore, meta-analysis was performed only for the nonextraction protocol. In treated Class II nonextraction patients, the average of the various effects was a reduction in the ANB angle of 1.56° (95% CI: 1.03, 2.09, P < .001) compared with untreated Class II subjects. Class II malocclusions treated with two maxillary-premolar extractions and four-premolar extractions produced estimated mean reductions in ANB of −1.88° and −2.55°, respectively. However, there is a lack of low-risk-of-bias studies.Conclusions:According to the existing low quality evidence, the apical base sagittal relationship in nonextraction, two-maxillary and four-premolar extractions Class II treatments decreases −1.56°, 1.88° and 2.55°, respectively. Further studies are necessary to obtain more robust information.  相似文献   

3.
Objective:To compare the postretention stability of maxillary incisors alignment in subjects with Class I and II malocclusion treated with or without extractions.Materials and Methods:The sample comprised 103 subjects with initial maxillary anterior irregularity greater than 3 mm and was divided into four groups: group 1 comprised 19 patients with Class I malocclusion treated with nonextraction (mean initial age = 13.06 years); group 2 comprised 19 patients with Class II malocclusion treated with nonextraction (mean initial age = 12.54 years); group 3 comprised 30 patients with Class I malocclusion treated with extractions (mean initial age = 13.16 years); group 4 comprised 35 patients with Class II malocclusion treated with extractions (mean initial age = 12.99 years). Dental casts were obtained at three different stages: pretreatment (T1), posttreatment (T2), and long-term posttreatment (T3). Maxillary incisor irregularity and arch dimensions were evaluated. Intergroup comparisons were performed by one-way analysis of variance followed by Tukey tests.Results:In the long-term posttreatment period, relapse of maxillary crowding and arch dimensions was similar in all groups.Conclusion:Changes in maxillary anterior alignment in Class I and Class II malocclusions treated with nonextractions and with extractions were similar in the long-term posttreatment period.  相似文献   

4.
The purpose of this study was to assess the profile changes in subjects with Class II, Division 1 malocclusions who were treated either with or without the extraction of the four first premolars. The assessments were made by 39 lay persons. Profile silhouettes on 91 (44 extraction and 47 nonextraction) patients were evaluated at three stages: pretreatment, posttreatment, and approximately 2 years after treatment. Photographs matched for age and sex were also evaluated on 20 normal untreated subjects (10 males and 10 females). All rater assessments were analyzed statistically as to the effects of the following variables: (a) occlusion, i.e., normal or Class II, (b) treatment rendered, i.e., extraction or nonextraction, (c) gender, i.e., male or female, and (d) stage of observation, i.e., pretreatment, end of treatment or in retention. The current findings indicate that (1) before treatment, lay persons perceived the profile of normal patients more favorably than untreated patients with Class II, Division 1 malocclusions. (2) Immediately after treatment, raters perceived the changes in the profile of the extraction group more favorably than those in the nonextraction and normal groups. (3) At the end of the observation period (approximately 2 years posttreatment), raters did not evaluate the profile of any of the groups as being more favorable, but all groups were perceived more favorably than at the initial observation. (4) Raters perceived the profile changes with treatment more favorably in female subjects than in male subjects. In conclusion, orthodontic treatment seems to have a favorable effect on the profiles of both the extraction and nonextraction groups, both short- and long-term. Therefore, when based on proper diagnostic criteria, the posttreatment changes in the facial profile were perceived as favorable in both the extraction and nonextraction Class II, Division 1 groups when compared with the pretreatment profile. (Am J Orthod Dentofac Orthop 1997;112:639-44.)  相似文献   

5.
AIM: The aim of the present study was to evaluate the sagittal and vertical development of the jaws in Class II, Division 1 (II/1) and Class II, Division 2 (II/2) malocclusions. In addition, facial morphology was to be investigated in probands with these malocclusions. PROBANDS AND METHODS: Maxillary and mandibular development was investigated with reference to lateral cephalograms of orthodontically untreated probands from the Belfast Growth Study at 7, 9, 11, 13 and 15 years of age. Moreover, development of facial width was assessed from the associated posteroanterior cephalograms, with radiographic magnifications being corrected in both the lateral and the posteroanterior cephalograms. A Class II/1 group (n = 17) and a Class II/2 group (n = 12) were compared with two control groups: a group with good occlusion (n = 18) and a Class I group (n = 37). RESULTS AND CONCLUSIONS: With respect to the sagittal position of the maxilla, no significant differences between the Class II groups and the controls were found. In the Class II/1 group, mandibular retrognathism was observed. The posterior position of the mandible present at 15 years of age had been present even at 7 years of age, and growth increments in the Class I and Class II/1 subjects were similar. In the Class II/2 groups no uniform pattern with respect to mandibular position was found. With respect to vertical development, a deficit in lower anterior facial height was found in the Class II/2 groups. In addition, between 7 and 15 years of age, growth increments in lower anterior facial height were significantly smaller in the Class II/2 subjects than in the controls. Furthermore, the Class II/2 groups displayed a more euryprosopic facial form on average. The cause of this characteristic facial morphology was the vertical deficit in lower anterior facial height. Overall, however, the broad variability and the small sample sizes, in particular of the Class II/2 groups, in the present study have to be seen as limitations.  相似文献   

6.
Four premolar extractions is a successful protocol to treat Class I malocclusion, but it is a less efficient way when compared with other Class II treatment protocols.

Objective:

The objective of this study was to evaluate the influence of anteroposterior discrepancy on the success of four premolar extractions protocol. For that, treatment efficiency of Class I and complete Class II malocclusions, treated with four premolar extractions were compared.

Methods:

A sample of 107 records from 75 Class I (mean age of 13.98 years - group 1) and 32 Class II (mean age of 13.19 years - group 2) malocclusion patients treated with four premolar extractions was selected. The initial and final occlusal status of each patient was evaluated on dental casts with the PAR index. The treatment time was calculated based on the clinical charts, and the treatment efficiency was obtained by the ratio between the percentage of PAR reduction and treatment time. The PAR index and its components, the treatment time and the treatment efficiency of the groups were statistically compared with t tests and Mann-Whitney U-test.

Results:

The Class II malocclusion patients had a greater final PAR index than Class I malocclusion patients, and similar duration (Class I - 28.95 mo. and Class II - 28.10 mo.) and treatment efficiency.

Conclusion:

The treatment of the complete Class II malocclusion with four premolar extractions presented worse occlusal results than Class I malocclusion owing to incomplete molar relationship correction.  相似文献   

7.
This study was undertaken to compare the post-treatment and long-term soft tissue profiles of successfully managed and stable Class II, division 1 malocclusions treated with either 4 first premolar extractions or nonextraction therapy. It was hypothesized that, if sound extraction decisions were made according to accepted treatment objectives and successful treatment outcomes were achieved, there should be no differences between groups in soft tissue profiles post-treatment and long-term post-retention. The sample consisted of 63 Caucasian adolescents (23 extraction, 40 nonextraction). Correction of the malocclusion was achieved using a combination of cervical headgear concurrent with mandibular growth and maxillary incisor retraction. Pretreatment, post-treatment, and long-term post-retention lateral cephalometric radiographs were evaluated. The soft tissue facial profiles of the extraction and nonextraction samples were the same following active treatment and long-term post-retention. Progressive flattening of the facial profile was observed in both samples. This flattening was attributed to the maturational changes associated with continued mandibular growth and nasal development and was not influenced by whether or not teeth were removed. Long-term lip positions were more retrusive than the ideals suggested by Ricketts and Steiner, but close to the values reported for normal, untreated adults of similar ages. The pretreatment position and thickness of the lower lip as well as the initial maxillomandibular skeletal relationship may be predictors of post-treatment or long-term lower lip position.  相似文献   

8.
The effect of first premolar extraction on vertical dimension.   总被引:4,自引:0,他引:4  
The purpose of this study was to evaluate the vertical changes occurring in Class I patients treated orthodontically with first premolar extraction and to compare these changes with those occurring in Class I patients treated orthodontically without extractions. Records of 40 Class I nonextraction cases (24 girls, 16 boys) and 40 Class I maxillary and mandibular first premolar extraction cases (23 girls, 17 boys) were obtained. The pretreatment and posttreatment cephalograms were digitized, and 6 linear and 8 angular cephalometric measurements were selected to evaluate vertical changes. Evaluation of the treatment results of the extraction and nonextraction cases showed that the vertical changes occurring after the extraction of maxillary and mandibular first premolars were not different than those occurring in the nonextraction cases.  相似文献   

9.
The purpose of this study was to compare the success rates of Class II subdivision malocclusion patients treated with either symmetric or asymmetric extractions. The sample consisted of 51 patients with Class II subdivision malocclusion. The patients were divided into 2 groups. Group 1 included 28 patients who were treated with 4 premolar extractions. The 23 patients in group 2 were treated with 3 premolar extractions (2 maxillary premolars and 1 mandibular premolar on the Class I side). The initial and final study models were evaluated by means of Grainger's treatment priority index (TPI). Individual evaluations of improvements in maxillary-to-mandibular dental midline deviation, overjet, and overbite were also made. The final mean TPI and the mean improvement in TPI and in the other variables of each group were compared with independent t tests. The results showed a statistically significant difference only for the improvement in maxillary-to-mandibular dental midline deviation of the groups. The 3-premolar-extraction group had a greater improvement of the initial interdental midline deviation. There is a tendency for a slightly better treatment success rate when Class II subdivision patients are treated with asymmetric extraction of 3 premolars, compared with extraction of 4 premolars.  相似文献   

10.
The aim of this study was to investigate the magnitude of mandibular incisor retraction to be expected during full fixed appliance mechanotherapy in Class II Division 1 malocclusions treated with premolar extractions when mandibular incisor retraction was not part of the treatment plan. The material consisted of pretreatment and posttreatment cephalometric films and dental casts of 70 Class II Division 1 malocclusion patients (33 males and 37 females) treated with the preadjusted edgewise appliances. The mandibular first premolars were extracted in 31 subjects, and the mandibular second premolars were extracted in 39. The pretreatment factors that suggested a basis for the extraction choice in the mandibular arch in these patients were found to include the ratio between posterior and anterior facial heights, the maxillary-mandibular plane angle, and the residual space in the mandibular arch. The mandibular incisors were retracted in only 65% of the patients. On average, the mandibular incisors were retracted by 1.02 mm relative to the nasion-pogonion line; there was no significant difference between the 2 extraction groups. Multiple regression analysis showed that the change in the mandibular incisor position is significantly correlated with the residual space in the mandibular arch, the initial distance between the mandibular incisor and the nasion-pogonion line, maxillary-mandibular angle, and the duration of crown labial torque in the mandibular incisors. In combination, these 4 factors could explain 61% of the change in the mandibular incisor position.  相似文献   

11.
The purpose of this study was to compare changes in the facial vertical dimension in patients with Class II division 1 malocclusion after the extraction of either mandibular first premolars or mandibular second premolars. The records of two groups of patients were used: one group was treated with extraction of mandibular first premolars (age: 13.2 +/- 1.5 years) and the other group with extraction of mandibular second premolars (age: 13.4 +/- 1.4 years). Each group consisted of 26 subjects (16 boys and 10 girls). Maxillary first premolars were extracted in both groups. The two groups were matched by sex, age (within six months), and facial divergence measured by maxillary-mandibular plane angle (MM angle) and ratio of posterior facial height to the total anterior facial height. Student's t-test was used to compare the two groups. Significance was predetermined at P < .05. Second premolar extraction was associated with more forward movement of the mandibular molars, but there was no significant difference in vertical facial growth between the two groups. In both groups, there was no significant change in the mandibular plane angle and the MM angle. The results of this study do not support the hypothesis that mandibular premolar extraction is associated with mandibular overclosure or reduction in the vertical dimension, or both, in subjects with Class II division 1 malocclusion.  相似文献   

12.
The purpose of this investigation was to assess the dentoskeletal effects and facial profile changes as well as the mechanism of Class II correction in adult Class II subjects treated by surgical mandibular advancement in combination with orthodontics. The subject material comprised 46 adults with a Class II, division 1 malocclusion treated by nonextraction with a mandibular sagittal split osteotomy as well as with pre- and postsurgical multibracket appliances. Lateral head films from before treatment and after treatment were analyzed. The results revealed the following statistically significant (P < .001) treatment changes: (1) the mandibular prognathism enhanced; (2) the sagittal interjaw base relationship improved; (3) the mandibular plane angle increased; (4) the lower anterior facial height increased; (5) the lower posterior facial height decreased; (6) the facial profile straightened; (7) the overjet and Class II molar relationship were corrected. Overjet reduction was accomplished by 63% skeletal and 37% dental changes. The Class II molar correction was accomplished by 81% skeletal 19% dental changes. In conclusion, it can be said that mandibular sagittal split osteotomy in combination with pre- and postsurgical orthodontics is an effective and consistent method for the correction of Class II, division 1 malocclusions and for the straightening of the facial profile. A negative effect of treatment counteracting Class II correction is an increase in the mandibular plane angle.  相似文献   

13.
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.  相似文献   

14.
This retrospective cephalometric study compared the nature of the skeletodental correction of maxillary second-molar extraction and nonextraction treatments in correcting Class II malocclusions. The sample comprised 50 Class II, deep-bite, low-angle adolescents; half were treated with maxillary second-molar extraction and half were treated without extraction. Pretreatment and posttreatment lateral cephalograms were analyzed. Analysis relied primarily on the method of Lysle Johnston that evaluates sagittal changes in the teeth and supporting bones relative to the functional occlusal plane. All 18 cephalometric variables examined were statistically equivalent between the 2 groups at the start of treatment. In contrast, several skeletodental treatment changes differed significantly. The maxillary second-molar extraction group exhibited distal movement of the maxillary first molar (1.2 mm vs 0.0 mm), and there was greater flaring of the mandibular incisors in the nonextraction group (9.1 degrees vs 3.5 degrees ). The upper incisor root was torqued lingually in both groups, but there was more anterior crown movement in the nonextraction group (2.0 mm vs 0.0 mm). Also, the extraction group finished active treatment 7 months sooner on average. Sagittal molar correction in the maxillary second-molar group was a result of distalizing in the maxillary arch, whereas anchorage was expended in the mandibular arch to correct the malocclusion in the nonextraction group. In properly selected Class II malocclusions, maxillary second-molar extraction is a viable alternative treatment choice.  相似文献   

15.
BACKGROUND: The purpose of this study was to identify clinical factors that predict treatment length for patients with Class II malocclusions. METHODS: A sample of 237 active retention patients representing 3 observational groups (Angle Class I nonextraction, and Class II Division 1 extraction and nonextraction), based on specific selection criteria, was obtained from 3 private offices. From the patient records, data were collected in these categories: (1) patient information, (2) model information, (3) pretreatment cephalogram information, and (4) treatment information. Two regression analyses were completed, with total treatment time as the dependent variable for both models. RESULTS: The first regression analysis (Class I and Class II patients) indicated significant predictors for the patient, model, and cephalometric variables. These predictors included age, pretreatment overjet, and pretreatment ANB angle. The second regression analysis (Class II treatment variables) identified the following factors as significantly associated with treatment length: (1) type of Class II appliance, (2) number of months of Class II appliance wear, (3) number of months of interarch elastic wear, (4) maxillary expansion, (5) number of debonds, and (6) average time (weeks) between appointments. CONCLUSIONS: Six variables explained 56.7% of the variation in Class II treatment length. Further research is required to help explain more of the variance associated with treatment duration.  相似文献   

16.
The growth potential of individuals with Class II malocclusions is of interest to the practicing orthodontist because such malocclusions constitute a significant percentage of cases. The purpose of this study was to evaluate on cross-sectional and longitudinal bases the changes in mandibular length and relationship and maxillary-mandibular relationships in untreated Class II subjects from deciduous to permanent dentition and also to evaluate the effects of orthodontic treatment, with and without the extraction of first premolars, on these relationships. Class II samples were compared with matched normal, untreated individuals. The Class II Division 1 (Class II/1) untreated sample comprised 30 subjects, 15 males and 15 females. Each subject had a complete set of data at three stages of dental development—namely, Stage I, after the completion of eruption of the deciduous dentition; Stage II, at the time when the permanent first molars and most of the incisors have erupted (i.e., in mixed dentition); and Stage III, at the completion of eruption of the permanent dentition, excluding third molars. The Class II treated sample comprised 44 subjects (21 males, 23 females) treated with four first-premolar extractions and 47 subjects (20 males, 27 females) treated without extraction. Treatment was accomplished with the use of an edgewise appliance, appropriate extraoral traction, and Class II elastics. The extraction decision was based mainly on the presence of crowding and profile consideration. Records on 35 normal subjects (20 males, 15 females) were available from the Iowa Longitudinal Facial Growth Study. Cephalograms for the normal individuals were matched to the corresponding ages of the Class II cases. With regard to these findings, few consistent differences were noted between the untreated Class II/1 and normal subjects on cross-sectional comparisons. The differences in mandibular length and position were more evident in the early stages of development than at later stages. Longitudinal comparisons of growth profiles indicated that the growth trends were essentially similar between the untreated Class II/1 and normal subjects in the various parameters compared. The comparisons of growth magnitude indicated the presence of greater skeletal facial convexity in the untreated Class II/1 subjects, accompanied by a tendency for a more retruded mandible. Initial comparisons between the Class II/1 treated groups and normal subjects indicated that the Class II/1 malocclusions were associated with a larger overjet, deeper overbite, and greater ANB angle. After a 5-year treatment and observation period, an overall “normalization” in the mandibular and maxillary-mandibular skeletal relationships was noted in the treated Class II/1 subjects in both the extraction and the nonextraction groups compared with normal subjects. The changes were more pronounced in the extraction group.(Am J Orthod Dentofacial Orthop 1998;113:661-73)  相似文献   

17.
The purpose of this paper was to compare retrospectively the effect on the soft tissues of two contrasting forms of treatment for Class II, Division 1 malocclusion. The first group of 30 persons exhibited uncrowded dentitions and were treated without extractions by means of the Andresen activator. No other appliance was used. The second group was also composed of 30 persons. These subjects were treated with the Begg appliance in its classical form. All of the Begg subjects showed varying amounts of crowding and were treated by extraction of four first premolars. It was believed that the Andresen appliance would maintain the incisors in the most labial position possible, while the Begg group with premolar extractions would involve the maximum lingual incisal movement. These groups were compared with a third group of 22 untreated persons who also exhibited Class II, Division 1 malocclusions. The overjets in the treated groups were successfully reduced in both cases by retraction of the upper incisors; in the Begg group only, retraction of lower incisors was also performed. The upper incisors were retracted substantially more in the Begg group than in the Andresen group, but there was only a slight difference within the two groups in the final position of the upper lip relative to a vertical reference line through sella. There was also a slight difference in the lengths of upper and lower lips within the two treated groups. The lower lip followed the lower incisors more closely in the Begg group. Both upper and lower lips "uncurled" in the treated groups and this probably allowed them to be held together with little strain. There was a wide variation in individual response in all three groups.  相似文献   

18.
A retrospective cephalometric study of Class II Division 1 malocclusions was carried out. Sixty patients with complete overbites were compared with another group of 60 matched in every respect, with the exception of having incomplete overbites. All patients were in the permanent dentition stage and aged between 10 and 14 years. An incomplete overbite was related to vertical variation in the skeletal pattern. This was demonstrated by greater anterior lower facial height, greater gonial angle, and steeper mandibular plane inclination. Incisor alveolar heights and molar heights did not vary between the groups. No differences between groups were noted for the degree of overjet reduction achieved during treatment, or in post retention relapse of overbite and overjet.  相似文献   

19.
INTRODUCTION: Treatment outcomes and duration of treatment for patients treated in university graduate orthodontic programs and private orthodontic practices were assessed and compared with the ABO objective grading system. METHODS: The treatment records of 139 randomly selected adolescents who had received comprehensive orthodontic treatment were examined. Seventy-seven subjects had been treated in 3 postgraduate orthodontic clinics, and 62 had been treated in 3 private orthodontic practices. Pretreatment, all subjects had Class II Division 1 malocclusions and ANB angles equal to or greater than 4 degrees . All patients were treated with premolar extractions. Posttreatment dental casts were measured and scored with the ABO objective grading system. RESULTS: No significant differences were found between the groups in the alignment, buccolingual inclination, and overjet components. Patients treated in private practice had significantly lower scores for marginal ridge height and occlusal relationship. Patients treated in the university programs had significantly lower scores for occlusal contact and interproximal contact components. CONCLUSIONS: There was no significant difference in the overall score, thus no significant difference in the overall quality of orthodontic treatment outcome between patients treated in university programs and private practices. However, the university group had a significantly larger sample variance for the overall score. There was no significant difference in the duration of the treatment between patients treated in a university setting and in a private practice.  相似文献   

20.
The purpose of this study was to determine the treatment effects of nonextraction edgewise therapy combined with cervical headgear on Class II, Division 1 malocclusions. Data from a sample of 43 treated patients with a mean age of 11 years 11 months and a mean treatment time of 2 years 8 months were recorded. A cephalometric appraisal was done and the initial and final measurements of points, lines, and angles based on accepted cephalometric analyses were compared. Student's t test for paired cases was used to evaluate the significance of all measurement changes. The significant findings were as follows: the inhibition of forward growth of the maxilla, downward tipping of the anterior part of the palate, reduction of flaring of the maxillary incisors, reduction of the facial convexity, and extrusion and mesial movement of maxillary and mandibular first molars. The overall results tend to indicate the efficacy of this treatment modality in the treatment of the Class II, Division 1 malocclusion.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号