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A cephalometric comparison of treatment effects and predictors of chin prominence in Class II Division 1 and 2 malocclusions with Forsus fatigue-resistant fixed functional appliance
Abstract
Background
The aim of this study was to cephalometrically evaluate and compare a treatment protocol in patients with Class II Division 1 (II/1) and Class II Division 2 (II/2), and to pursue predictors of the change in chin prominence.
Methods
This retrospective study included 30 patients with Class II/1 and 25 patients with Class II/2 treated with the Forsus appliance, in combination with fixed appliances. Pre- and posttreatment lateral cephalometric radiographs were collected, and 28 measurements were recorded. A two-sample t test was used for the pretreatment comparison among the two Divisions. Paired t tests were used to evaluate the treatment changes within each group. Analysis of covariance was used to compare the treatment changes between the Divisions after adjusting for the baseline value, age, gender, treatment duration, and time with the Forsus appliance. The Simes multiple testing procedure permitted adjustment for multiple comparisons. Regression analysis was performed to identify predictors explaining the change in chin prominence.
Results
Class II correction occurred in both Divisions, mainly through dentoalveolar effects. There were no significant cephalometric differences found in the mean treatment changes between the Divisions. The pretreatment Gonial angle, molar eruption, lower incisor inclination, mandibular body length, and soft tissue chin thickness had a significant impact on the treatment changes in chin prominence.
Conclusions
Treatment with the Forsus in combination with preadjusted fixed appliances leads to a favorable treatment outcome and produces similar treatment changes in both Class II Divisions.
... Various clinical studies showed significant reduction in overjet, overbite, and interincisal angle [20][21][22]. Franchi and Aras., et al. [20,22] [11,19]. He also suggested that the mandibular molars and incisors moved mesially which improved the overjet and also there was extrusion of mandibular first molars [18,19,[21][22][23]. ...
... Franchi and Aras., et al. [20,22] [11,19]. He also suggested that the mandibular molars and incisors moved mesially which improved the overjet and also there was extrusion of mandibular first molars [18,19,[21][22][23]. Maxillary incisors were palatally tipped, backwardly placed, and showed a greater vertical eruption [18,20,21]. ...
... He also suggested that the mandibular molars and incisors moved mesially which improved the overjet and also there was extrusion of mandibular first molars [18,19,[21][22][23]. Maxillary incisors were palatally tipped, backwardly placed, and showed a greater vertical eruption [18,20,21]. The mandibular incisors were proclined with a significant increase in IMPA [21,22]. ...
... For instance, it has been reported that incorporating second molars in the posterior anchorage unit may facilitate control in maximum anchorage extraction cases and may help control mandibular incisor proclination in patients undergoing OT with functional appliances and/or Class II dentoalveolar correctors. 17,18 In addition, Levine et al. indicated that second molar angulation to the occlusal plane is significantly correlated with anteroposterior skeletal discrepancies and, particularly, with skeletal Class III malocclusion; this may lead to occlusal interferences in postsurgical orthognathic cases. 19 Further studies are needed to assess the impact of second molar bonding in patients with severe types of malocclusion receiving OT with extractions, functional appliances, and/or combined with orthognathic surgery. ...
Objectives
To compare orthodontic treatment (OT) outcome in adolescents undergoing nonextraction fixed OT with or without bonding of second molars using the score of the American Board of Orthodontics Cast Radiograph Evaluation (C-R-Eval).
Materials and Methods
This study included healthy adolescents with skeletal Class I or mild Class II/Class III malocclusion, normal or deep overbite (OB), and mild-to-moderate dental crowding (<5 mm) who underwent nonextraction fixed OT with (“bonded” group) or without (“not-bonded” group) bonding of second molars. Patient treatment records, pre- and posttreatment digital models, lateral cephalograms, and orthopantomograms were assessed. The evaluated outcomes included leveling of the curve of Spee (COS), OB, control of incisor mandibular plane angle (IMPA), number of emergency visits (related to poking wires and/or bracket failure of the terminal molar tubes), treatment duration, and C-R-Eval. Treatment variables were compared across time points and among groups.
Results
The sample included 30 patients (mean age 16.07 ± 1.80 years) in the bonded group and 32 patients (mean age 15.69 ± 1.86 years) in the not-bonded group. The mean overall C-R-Eval score was significantly higher (P < .001) in the not-bonded group (25.25 ± 3.98) than in the bonded group (17.70 ± 2.97). There were no significant differences in mean changes of COS, OB, IMPA, or treatment duration among groups. The mean number of emergency visits was significantly higher in the bonded (3.3 ± 0.6) than the not-bonded group (1.9 ± 0.4) (P < .001).
Conclusions
Bonding of second molars enhances the outcome of nonextraction fixed OT as demonstrated by the C-R-Eval without increasing treatment duration, irrespective of more emergency visits.
... Various orthodontic appliances were designed to manage the anteroposterior and vertical discrepancy, such as miniscrew, Forsus, lingual orthodontic appliance, headgear and so on [1][2][3][4][5][6]. And the miniscrew is widely utilized in orthodontic clinical practice as anchorage. ...
Background: While various orthodontic appliances were designed to manage the anteroposterior and vertical discrepancy, miniscrew was one of the powerful appliances and was widely utilized as anchorage to treatment the anteroposterior relationship. Method and Result: In the study we treated the severe Class Ⅱ skeletal discrepancy subject with protrude upper incisors and mandibular hypoplasia by the vertical control with the miniscrew. After two years treatment, all the objectives were achieved. The skeletal Class Ⅱ discrepancy was improved (ANB 6.3), the protrude upper incisors were treated (U1 angulation 92.8, U1-L1 120.7) and the occlusive plan was leveled (Occ Plane 8.2). Class Ⅰ molars and canines relationship were obtained. Conclusion: The vertical control was vital for the correction of anteroposterior discrepancy. The anteroposterior, vertical and transverse dimension and the time, especially the long term of post-treatment stability, interacts with each other.
Purpose:
To evaluate the effects of upper occlusal plane (UOP) inclination and incisor decompensations on the outcome of surgical Class II patients.
Materials and methods:
Pretreatment (T0), preoperative (T1), and posttreatment (T2) cephalograms of 30 surgical Class II patients were included. Cephalometric measurements were performed using the Dolphin Imaging Software in this retrospective study. The differences between time points were analyzed with repeated measures ANOVA. Spearman correlation test was used to determine any correlations between either the UOP alterations or incisor decompensations and the cephalometric variables.
Results:
A significant improvement was obtained in the sagittal skeletal, dental variables, and soft tissue B point. Significant correlations were found between the decompensation achievement ratio and the change of the convexity angle. The relative percentage ratio (RPR) of the lower incisor was correlated with Wits appraisal, ANB, and Convexity Angle at the T2 stage. The RPR of the upper incisor was found to be correlated with lip strain. The relative surgical correction ratio of the UOP angle was found to be correlated with the surgical change of Wits appraisal and convexity angle. The RPR of the UOP angle was correlated with the SNB, ANB, and SN-GOGN angles at the T2 stage.
Conclusions:
Significant improvement in the incisor inclinations was achieved, but the incisors were inadequately decompensated at the preoperative phase. Surgical correction was limited by the inadequate presurgical decompensation. The surgical alteration of the UOP should be taken into consideration for the surgical planning to obtain better outcomes for Class II patients.
Objective:
To evaluate the skeletal, dentoalveolar, and soft tissue effects of the Forsus FRD appliance with miniplate anchorage inserted in the mandibular symphyses and to compare the findings with a well-matched control group treated with a Herbst appliance for the correction of a skeletal Class II malocclusion due to mandibular retrusion.
Materials and methods:
The sample consisted of 32 Class II subjects divided into two groups. Group I consisted of 16 patients (10 females and 6 males; mean age, 13.20 ± 1.33 years) treated using the Forsus FRD EZ appliance with miniplate anchorage inserted in the mandibular symphyses. Group II consisted of 16 patients (9 females and 7 males; mean age, 13.56 ± 1.27 years) treated using the Herbst appliance. Seventeen linear and 10 angular measurements were performed to evaluate and compare the skeletal, dentoalveolar, and soft tissue effects of the appliances using paired and Student's t-tests.
Results:
Both appliances were effective in correcting skeletal class II malocclusion and showed similar skeletal and soft tissue changes. The maxillary incisor was statistically significantly more retruded in the skeletally anchored Forsus FRD group (P < .01). The mandibular incisor was retruded in the skeletally anchored Forsus FRD group (-4.09° ± 5.12°), while it was protruded in the Herbst group (7.50° ± 3.98°) (P < .001).
Conclusion:
Although both appliances were successful in correcting the skeletal Class II malocclusion, the skeletally anchored Forsus FRD EZ appliance did so without protruding the mandibular incisors.
Background
The objective of this study was to evaluate the treatment effects of Forsus™ Fatigue Resistant Device (FRD; 3M Unitek, Monrovia, CA, USA) in growing patients with Class II non-extraction malocclusions.
Methods
A retrospective sample of 24 class II patients treated consecutively with the FRD followed by comprehensive orthodontic treatment was compared to a sample of untreated control subjects from the Bolton Brush Study who was matched in age, sex, and craniofacial morphology. Lateral cephalometric radiographs were taken before treatment (T1) and after removal of fixed appliances (T2). Growth changes were subtracted from the treatment changes to obtain the treatment effects of the appliance. Data were analyzed using ANOVA and a match paired t test.
Results
Significant differences were found between the treated and control groups for 12 of the 29 measured variables (Co-Gn minus Co-Apt, Wits, Is-OLp, Ii-OLp, overjet, Mi-OLp, molar relationship, overbite, Mic-ML, SNA, ANB, and Ii-ML). With 27.8 months of treatment, all patients were corrected to a class I dental arch relationship. Overjet and molar relationships were improved by an average of 4.7 and 3.1 mm, respectively. This was contributed by a 1.2 mm of restraint in forward maxillary growth, 0.7 mm of forward movement of the mandible, 1.5 mm of backward movement of the maxillary incisors, 1.3 mm forward movement of the mandibular incisors, 0.5 mm backward movement of the maxillary molars, and 1.3 mm of forward movement of the mandibular molars. The overbite was decreased by 2 mm with no significant change in the occlusal, palatal, or mandibular plane. Individual variations in response to the FRD treatment were large for most of the parameters tested. Significant differences in treatment changes between male and female subjects were found only in a few parameters measured.
Conclusions
These results demonstrate that significant overjet and overbite corrections can be obtained with the Forsus FRD in conjunction with comprehensive orthodontic treatment.
Objectives
We evaluated the skeletal and dentoalveolar effects of the Forsus Fatigue Resistance Device (FRD) and the Twin Block appliance (TB) in comparison with nontreated controls in the treatment of patients with class II division 1 malocclusion.
Materials and methods
This retrospective study included three groups: TB (n=37; mean age, 11.2 years), FRD (n=30; mean age, 12.9 years), and controls (n=25; mean age, 12.6 years). Lateral cephalograms were evaluated at T1 (pretreatment) and at T2 (postappliance removal/equivalent time frame in controls). Cephalometric changes were evaluated using the Clark analysis, including 27 measurements.
Results
Sagittal correction of class II malocclusion appeared to be mainly achieved by dentoalveolar changes in the FRD group. The TB was able to induce both skeletal and dentoalveolar changes. A favorable influence on facial convexity was achieved by both groups. Significant upper incisor retroclination occurred with the TB (−12.42°), whereas only −4° was observed in the FRD group. The lower incisors proclined more in the FRD group than the TB group. Incisor overjet reduction was 62% in the TB group versus 56% in the FRD group. Molar relation was corrected in both functional groups, resulting in a class I relation, although no change appeared in the control sample.
Conclusion
Both appliances were effective in correcting the class II malocclusion. Both the FRD and the TB induced significant maxillary and mandibular dentoalveolar changes; skeletal changes were induced by TB but not FRD therapy.
Based on our literature search, we found that the use of miniplate anchorage with Forsus fatigue-resistance device (FRD) has not yet been reported. Therefore, the aim of the present case report was to present the treatment of a patient with skeletal Class II malocclusion with mandibular retrusion using Forsus FRD with miniplate anchorage. Fixed appliances with 0.022-inch slots were attached to the maxillary teeth and after 8 months of the leveling and alignment of the upper arch, 0.019 × 0.025-inch stainless steel archwire was inserted and cinched back. Two weeks after the placement of the miniplates bilaterally at the symphysis of the mandible, Forsus FRD was adjusted to the miniplates with a 35-mm length of rod chosen. Nine months after the skeletal anchored Forsus worn, Class I canine and molar relations were achieved and overjet was eliminated.
Objective
To evaluate the active-treatment effects of the Forsus fatigue resistant device (Forsus) during comprehensive correction of Class II malocclusion in growing patients.
Methods
Fifty-four patients (mean age, 12.5 ± 1.2 years) with Class II division 1 malocclusion were consecutively treated with fixed app-liances in combination with Forsus. Lateral cephalograms were analyzed at the beginning of the fixed treatment (T1), Forsus insertion (T2), its removal (T3), and end of the comprehensive therapy (T4). Statistical comparisons were carried out by repeated-measures ANOVA with Tukey's post-hoc test (p < 0.05).
Results
The overall therapeutic effects were mainly dentoalveolar and occurred mostly during the active treatment with Forsus (T2-T3, mean duration = 0.5 ± 0.1 years). The overjet and overbite decreased significantly (-3.5 and -1.5 mm, respectively) and the molar relationship improved by 4.3 mm. These changes were associated with significant retroclination of the maxillary incisors (-3.1°), proclination and intrusion of the mandibular incisors (+5.0° and -1.5 mm, respectively), and mesialization of the mandibular molars (+2.0 mm).
Conclusions
Forsus had mainly dentoalveolar effects and contributed largely to the overall therapeutic outcome.
Objective:
To evaluate treatment and posttreatment dentoskeletal effects induced by the Forsus device (FRD) in growing patients with Class II malocclusion in a retrospective controlled clinical study.
Materials and methods:
Thirty-six Class II patients (mean [SD] age 12.3 [1.2] years) were treated consecutively with the FRD protocol and compared with a sample of 20 subjects with untreated Class II malocclusion (mean [SD] age 12.2 [0.9] years). Lateral cephalograms were taken at the beginning of treatment, at the end of comprehensive treatment (after 2.3 ± 0.4 years), and at a postretention period (after 2.3 ± 1.1 years from the end of comprehensive treatment). Statistical comparisons were carried out with the unpaired t-test and Benjamini-Hochberg correction (P < .05).
Results:
After comprehensive treatment, the FRD sample showed a significant restriction of the sagittal maxillary growth together with a significant correction in overjet, overbite, and molar relationship. During the overall observation interval, the FRD group exhibited no significant sagittal or vertical skeletal changes, while significant improvements were recorded in overjet (-3.8 mm), overbite (-1.5 mm), and molar relationship (+3.7 mm).
Conclusion:
The FRD protocol was effective in correcting Class II malocclusion mainly at the dentoalveolar level when evaluated 2 years after the end of comprehensive treatment.
Objective:
To investigate patients' experiences with the Forsus Fatigue Resistant Device (FFRD).
Methods:
This was a survey focused on patient's comprehensive experience with FFRD, both initially and after several months of wear, including the patient's overall impression of the appliance. The survey was administered to 70 patients wearing FFRD in both university and private practice settings.
Results:
A high percentage (81.5%) reported a neutral to favorable experience with FFRD; 89.8% reported growing accustomed to the appliance within 4 weeks. The majority of those who had previously worn rubber bands found FFRD to be "easier." Cheek irritation was the most serious side effect (about 50%). Cheek irritation and other negative effects generally decreased over time.
Conclusions:
The FFRD is relatively well accepted by patients. Most patients experience some discomfort and functional limitations; however, the effect generally diminishes with time, and patients adapt to the appliance. Practitioners should be especially vigilant about problems with cheek irritation.
A modification of the Bonferroni procedure for testing multiple hypotheses is presented. The method, based on the ordered p-values of the individual tests, is less conservative than the classical Bonferroni procedure but is still simple to apply. A simulation study shows that the probability of a type I error of the procedure does not exceed the nominal significance level, α, for a variety of multivariate normal and multivariate gamma test statistics. For independent tests the procedure has type I error probability equal to α. The method appears particularly advantageous over the classical Bonferroni procedure when several highly-correlated test statistics are involved.
To describe and analyze the skeletal and dental characteristics associated with Class II division 1 (Class II/1) and Class II division 2 (Class II/2) malocclusions in the anteroposterior and vertical dimensions.
A total of 551 lateral cephalograms were used; 293 films of Class II/1 and 258 films of Class II/2 malocclusions. Lateral cephalographs were traced and analyzed. Parameters for both malocclusions were compared with each other and with the norms calculated for the Jordanian population in another study.
The maxilla was prognathic in both malocclusions. The mandible was retrognathic in Class II/1 and orthognathic in Class II/2. Vertically, LAFH was significantly reduced in patients with Class II/2 compared with subjects with Class II/1 who exhibited a significantly increased LAFH. In Class II/1, the lower incisors were proclined and the interincisal angle was reduced, while in Class II/2 the lower incisors were at a normal inclination and the interincisal angle was significantly increased.
Class II/2 may be considered as a separate entity which differs in almost all skeletal and dental features from Class I and Class II/1. A Class II skeletal pattern and reduced interincisal angle were common features of Class II/1 malocclusion, while a Class II skeletal pattern, increased interincisal angle, and skeletal deep bite were common features of Class II/2 malocclusion.
To evaluate the Forsus Fatigue Resistant Device (FRD) as a compliance-free alternative to Class II elastics.
A sample of 34 (14 female, 20 male) consecutively treated nonextraction FRD patients (12.6 years of age) were matched with a sample of 34 (14 female, 20 male) consecutively treated nonextraction Class II elastics patients (12.2 years of age) based on four pretreatment variables (ANB, L1-GoMe, SN-GoMe, and treatment duration). Pretreatment and posttreatment cephalometric radiographs were traced and analyzed using the pitchfork analysis and a vertical cephalometric analysis. t-Tests were used to evaluate group differences. Group differences were evaluated using t-tests.
No statistically significant differences were found in the treatment changes between the groups. There was a general trend for mesial movement of the maxilla, mandible, and dentition during treatment for both groups. The mandibular skeletal advancement and dental movements were greater than those in the maxilla, which accounted for the Class II correction. Lower incisor proclination was evident in both groups. Vertically, the maxillary and mandibular molars erupted during treatment in both groups, while lower incisors proclined. With the exception of lower molar mesial movements and total molar correction, which were significantly (P < .05) greater in the Forsus group, there were no statistically significant group differences in the treatment changes.
The Forsus FRD is an acceptable substitute for Class II elastics for noncompliant patients.
To compare the dentoskeletal changes produced by the Twin-block appliance (TB) followed by fixed appliances vs the Forsus Fatigue Resistant Device (FRD) in combination with fixed appliances in growing patients having Class II division 1 malocclusion.
Twenty-eight Class II patients (19 females and 9 males; mean age, 12.4 years) treated consecutively with the TB followed by fixed appliances were compared with a group of 36 patients (16 females and 20 males; mean age, 12.3 years) treated consecutively with the FRD in combination with fixed appliances and with a sample of 27 subjects having untreated Class II malocclusion (13 females and 14 males; mean age, 12.2 years). Mean observation interval was 2.3 years in all groups. Cephalometric changes were compared among the three groups by means of ANOVA and Tukey's post hoc tests.
The FRD produced a significant restraint of the maxilla compared with the TB and control samples (SNA, -1.1° and -1.8°, respectively). The TB sample exhibited significantly greater mandibular advancement and greater increments in total mandibular length than either the FRD or control groups (SNB, 1.9° and 1.5°, respectively; and Co-Gn, 2.0 mm and 3.4 mm, respectively). The FRD produced a significantly greater amount of proclination of the mandibular incisors than what occurred with the TB or the control samples (2.9° and 5.6°, respectively).
The TB appliance produced greater skeletal effects in terms of mandibular advancement and growth stimulation while the Forsus caused significant proclination of the mandibular incisors.
The aim of this longitudinal 32-year follow-up investigation was to analyze the very long-term effects of Herbst treatment on the dentoskeletal structures. We followed 14 patients from a sample of 22 with Class II Division 1 malocclusions who were consecutively treated with the banded Herbst appliance at ages 12 to 14 years. The subjects were reexamined after therapy at the ages of 20 years (when the radius epiphysis/diaphysis plate was closed) and 46 years.
Lateral head films were analyzed from before (T1) and after (T2) treatment, and at 6 years (T3) and 32 years (T4) after treatment.
(1) In the standard analysis (angular measurements) during the T2 to T3 period of 6 years, significant skeletal changes were the following: increase of the SNB (1.0°; P <0.01), decrease of the ANB (0.9°; P <0.01), and decrease of the ML/NSL (2.5°; P <0.001). During the T3 to T4 period of 24 years, no further significant angular changes occurred. (2) In the analysis of the sagittal changes in the occlusion (linear measurements) during the T2 to T3 period of 6 years, the mandible (6.1 mm; P <0.001) and the maxilla (3.0 mm; P <0.01) grew forward. During the T3 to T4 period of 24 years, the mandible (2.8 mm; P <0.01) and the maxilla (3.1 mm; P <0.01) continued to grow forward. Thus, during the total posttreatment (T2-T4) period of 32 years, there was continuous forward growth of the mandible (8.9 mm; P <0.001) and the maxilla (6.1 mm; P <0.001). (3) The analysis of superimposed lateral head films showed in all 14 subjects large amounts of sagittal and vertical skeletofacial growth during T3 to T4.
In all 14 subjects, large amounts of sagittal and vertical skeletofacial growth occurred after the age of 20 years. However, the question of when, during the period from 20 to 46 years, growth had come to an end remains open. Closure of the radius epiphysis/diaphysis plate is not useful as an indicator for completed skeletofacial growth. Our findings indicate the importance of considering late adult skeletofacial growth in dentofacial orthopedics, orthognathic surgery, and tooth implantology with respect to treatment timing, posttreatment retention, and relapse.
Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.
Any malocclusion, most particularly Class II, must be diagnosed and treated on the basis of its many components, and not simplified to one or only several spatial relationships. Research points out the inability of common approaches of treatment to transform a Class II, Division 1 phenotype to a facial pattern with normal skeletal relationships that would be expected with a Class I phenotype. These observations underscore the structural differences between the various classes of malocclusion in addition to the definition of treatment outcome as the cumulative effect of small to moderate changes in the various skeletal and dentoalveolar components of the malocclusion, rather than a major change in simply one of its components. Available data on component growth in untreated Class II further support these observations.
Sleep Disordered Breathing (SDB) is gradually being recognized today as having significant health implications for individuals who are suffering from this condition and especially those who remain undiagnosed and may not be receiving the necessary treatment. Today, more attention is being directed to identifying potential risk factors that contribute to individuals developing this condition. Moreover, it has been established that certain craniofacial morphological characteristics have been associated with SDB. This article discusses the diagnostic, treatment planning and informed consent considerations involved in managing the Class II malocclusion with considerations related to SDB.
We propose that malocclusions with predominantly vertical problems (open bite and deep bite) are challenging to treat because the skeletal and dentoalveolar components defining the vertical discrepancy are subject to a myriad of arrangements. Accordingly, the purpose of this paper is to relate how these variations must be factored into proper diagnosis, and demonstrate that individual characterization and not a “generic” phenotype for open bite and deep bite should be the basis for treatment planning. Variations include the coexistence of hyperdivergence (“high angle”) with deep rather than open bite. Specifically, the importance of component analysis is presented along with the nuances of classification of malocclusion in the vertical dimension. The state of current evidence is presented, including (on average) the constancy of the vertical growth pattern, the potential for a vertical problem to mask or worsen a sagittal dysmorphology, the possible contribution of environment and genetics in different extents to maxillary and mandibular problems, and the need to explore many unknown facts about the vertical dimension.
Class II malocclusions are of interest to the practicing orthodontists since they constitute a significant percentage of the cases they treat. In individuals with normal occlusion and skeletal relationship, the amount of maxillary and mandibular growth is synchronized and the result is a well-balanced and esthetically pleasing profile. In individuals with Class II malocclusions, there is an anteroposterior discrepancy between the maxillary and mandibular dentitions, which may or may not be accompanied with a skeletal discrepancy. In growing individuals, the success of treatment is dependent, to a great extent, on the ability of the clinician to influence the relative growth changes in the maxilla and mandible. The purpose of this article is to provide a perspective on the characteristics, development, etiology, and broad treatment considerations in Class II malocclusions.
The aim of this study was to evaluate the effectiveness of early orthodontic treatment with the Twin-block appliance for the treatment of Class II Division 1 malocclusion. This was a multi-center, randomized, controlled trial with subjects from 14 orthodontic clinics in the United Kingdom.
The study included 174 children aged 8 to 10 years with Class II Division 1 malocclusion; they were randomly allocated to receive treatment with a Twin-block appliance or to an initially untreated control group. The subjects were then followed until all orthodontic treatment was completed. Final skeletal pattern, number of attendances, duration of orthodontic treatment, extraction rate, cost of treatment, and the child's self-concept were considered.
At the end of the 10-year study, 141 patients either completed treatment or accepted their occlusion. Data analysis showed that there was no differences between those who received early Twin-block treatment and those who had 1 course of treatment in adolescence with respect to skeletal pattern, extraction rate, and self-esteem. Those who had early treatment had more attendances, received treatment for longer times, and incurred more costs than the adolescent treatment group. They also had significantly poorer final dental occlusion.
Twin-block treatment when a child is 8 to 9 years old has no advantages over treatment started at an average age of 12.4 years. However, the cost of early treatment to the patient in terms of attendances and length of appliance wear is increased.
Forty-two cases of Class II, Division 2 malocclusions were selected on the basis of Strang's first six steps. There were nineteen male and twenty-three female patients in the study. The average age was 12.5 years. These cases were compared with the normal sample of the Alabama Analysis. The Class II, Division 2 sample was compared to a sample of fifty-seven Class II, Division 1 cases. Means, standard deviations, and analyses of covariance, adjusted for age and sex, were derived. Illustrations show, numerically and graphically, the similarities and differences between Class II, Division 2 malocclusions and normal occlusions. Fig. 4 shows the comparison between the Class II, Division 1 and the Class II, Division 2 typical profiles.
Mandibular treatment changes were related to somatic maturation in 70 consecutive cases of Class II malocclusion (52 boys and 18 girls, aged 10 to 16 years) treated with the Herbst appliance for an average period of 7 months. Sagittal and vertical alterations in mandibular condylar growth and sagittal changes in molar and incisor tooth position were analyzed by means of mouth-open profile roentgenograms. The somatic maturity level of the patients was assessed by means of longitudinal growth records of standing height. The treatment period was related to the peak height velocity by dividing the patients into three growth-period groups: prepeak, peak, and postpeak. Herbst treatment resulted in Class I dental arch relationships in all patients. Post-Herbst treatment changes were not evaluated in this study. Sagittal condylar growth was increased and the mandibular molars and incisors were moved anteriorly. When the mandibular skeletal and dental changes were related to the subjects' somatic maturation, significant differences between the different growth periods existed in boys and tendencies were noted in girls as follows: sagittal condylar growth was most pronounced in the peak period, anterior molar movement was equally large in all growth periods, and anterior incisor movement was most extensive in the postpeak period. To take advantage of the increase in condylar growth response and to reduce the time of posttreatment retention, it is suggested that Herbst therapy be instituted close to peak height velocity.
The purpose of this study was to compare longitudinally the changes that occur in dentofacial structures from the deciduous to the permanent dentitions in untreated Class II division 1 and normal individuals. Complete records were assembled for 65 subjects at three stages of development: at the completion of the deciduous dentition, after the first permanent molars had erupted completely, and after the permanent dentition had erupted completely (third molars excluded). On a cross-sectional basis, only mandibular length (Ar-Pog) differed significantly in the two groups, and then only during the earlier stages of development; by the later stage, the difference was not significant, indicating that some "catch up" growth may occur in Class II individuals. Longitudinal comparisons of the curve profiles, i.e., growth trends between Class II division 1 and normal subjects, indicated that there were no significant differences between the two groups except in upper lip protrusion. Comparisons of the total change from the deciduous to the permanent dentition indicated the presence of a number of significant differences between Class II division 1 and normal subjects, including larger magnitude of maxillary and mandibular lengths in the normal group and greater skeletal and soft tissue convexities in the Class II group.
This cephalometric study evaluated skeletal and dentoalveolar changes induced by the Twin-block appliance in 2 groups of subjects with Class II malocclusion treated at different skeletal maturation stages in order to define the optimal timing for this type of therapy. Skeletal maturity in individual patients was assessed on the basis of the stages of cervical vertebrae maturation. The early-treated group was composed of 21 subjects (11 females and 10 males). Mean age of these subjects at time 1 (immediately before treatment) was 9 years +/- 11 months, and at time 2 (immediately after discontinuation of the Twin-block appliance) was 10 years 2 months +/- 11 months. According to the cervical vertebrae maturation staging at times 1 and 2, the peak in growth velocity was not included in the treatment period for any of the subjects in the early group. The late-treated group consisted of 15 subjects (6 females and 9 males). Mean age of this group was 12 years 11 months +/- 1 year 2 months at time 1 and 14 years 4 months +/- 1 year 3 months at time 2. In the late group, treatment was performed during or slightly after the onset of the pubertal growth spurt. Both treated samples were compared with control samples consisting of subjects with untreated Class II malocclusions also selected on the basis of the stage in cervical vertebrae maturation. A modification of Pancherz's cephalometric analysis was applied to the lateral cephalograms of all examined groups at both time periods. Linear and angular measurements for mandibular dimensions, cranial base angulation, and vertical relationships were added to the original analysis. Annualized differences for all the variables from time 1 to time 2 were calculated for both treated groups and contrasted to the annualized differences in the corresponding untreated groups by means of nonparametric statistics. The findings of this short-term cephalometric study indicate that optimal timing for Twin-block therapy of Class II disharmony is during or slightly after the onset of the pubertal peak in growth velocity. When compared with treatment performed before the peak, late Twin-block treatment produces more favorable effects that include: (1) greater skeletal contribution to molar correction, (2) larger increments in total mandibular length and in ramus height, and (3) more posterior direction of condylar growth, leading to enhanced mandibular lengthening and to reduced forward displacement of the condyle in favor of effective skeletal changes. The importance of the biological evaluation of skeletal maturity in individual patients with Class II disharmony to be treated with functional appliances is emphasized.
The purpose of this study was to evaluate the effect of unilateral disk displacement with reduction (UDDR) on the skeletal and dental pattern of affected individuals. There were 18 symptomatic female patients and 46 asymptomatic normal female volunteers. All study participants had bilateral high-resolution magnetic resonance scans in the sagittal (closed and open) and coronal (closed) planes to evaluate the temporomandibular joints. Linear and angular cephalometric measurements were taken to evaluate the skeletal, denture base, and dental characteristics of the two groups. Analysis of variance was used to compare the symptomatic with the control subjects. A few skeletal differences were found. There was an overall reduction in length of the anterior (S-Na) and posterior (S-Ba) cranial base measurements in the UDDR group. The cranial base angle was also increased. Both upper and lower dentures bases were retropositioned. The posterior ramal height (Ar-Go) was shorter in the symptomatic group. This study showed that alterations in skeletal morphology may be associated with UDDR. The mechanisms that produce DD or the mechanisms that cause this skeletal alteration are yet to be clarified. This study suggests that subjects with UDDR may manifest altered craniofacial morphology. The clinician should be aware of this possibility, especially for growing patients.
The purpose of this study was to evaluate the effect of bilateral disk displacement without reduction (BDDN) on the skeletal and dental pattern of affected individuals. There were 59 symptomatic female patients and 46 asymptomatic normal female volunteers. All study participants had bilateral high-resolution magnetic resonance imaging scans in the sagittal (closed and open) and coronal (closed) planes to evaluate the temporomandibular joints. Linear and angular cephalometric measurements were taken to evaluate the skeletal, denture base, and dental characteristics of the two groups. A smaller cranial base length (Ba-Na) was found in the symptomatic group. The facial plane angle was smaller, and the angle of convexity was larger because of the retropositioned mandible. The lower denture base was also retruded as shown by the smaller SNB angle. The BDDN group exhibited a larger overjet. The mandibular plane angle was steeper, the Y-axis was more vertical (S-Gn to FH), the posterior ramal height (Ar-Go) was shorter, and the angle between the mandibular and the palatal plane (PP to MP angle) was increased in the symptomatic group. No significant dental differences were found. This study showed that alterations in skeletal morphology might be associated with BDDN. This study suggests that subjects with BDDN may manifest altered craniofacial morphology. The clinician should be aware of that possibility, especially for the growing patients and the surgical candidates.
Treatment of malocclusion of the teeth: Angle's system. Philadelphia: White Dental Manufacturing Co
- E H Angle
Angle EH. Treatment of malocclusion of the teeth: Angle's system. Philadelphia: White Dental Manufacturing Co; 1907.