[Treatment of class II for growing patients by clear aligners: which protocol?]

INTRODUCTION

Skeletal class II, frequently associated with retromandibular and overjet > 2 mm, lead to functional and aesthetic damage, that orthodontic treatment has to correct. The aim of this article is to describe a treatment protocol by aligners for class II growing patients according to the value of the class II and the maturity state of cervical vertebrae.

MATERIALS AND METHODS

Through clinical cases, this article will present three different therapeutic approaches depending on the growth state.

RESULTS

The study of the auxologic potential and determination of the bone age (radiological analysis of the maturation of the cervical vertebrae) will allow to determine the best moment to treat class II and the most appropriate therapeutic attitude according to growing state.

DISCUSSION

This study before treatment is essential to adapt an individualized clinical protocol to each patient. In this way, aligners are devices that respond well to this imperative because they are customizable in view of the strategy and the treatment plan considered by the practitioner. We must keep in mind, however, that with any therapy, it is essential to ensure good patient compliance.

Assessment of dental arches in patients with Class II division 1 and division 2 malocclusions using 3D digital models in a Syrian sample

AIM

(1) to evaluate the applicability of using 3D digital models in the assessment of Class II Division 1 (Cl II-1) and Class II Division 2 (Cl II-2) malocclusion in a Syrian sample, (2) to detect any significant differences between the two groups in tooth and arch widths, anterior (ABR) and overall Bolton ratios, PAR Index, and (3) to detect any gender differences in these variables.

DESIGN AND SETTING

observational, cross-sectional study for descriptive and analytical purposes at the Orthodontic Dept., University of Al-Baath Hamah Dental School, Hamah, Syria.

PARTICIPANTS

A disproportionate multi-stratified random sampling was employed to select 36 Cl II-1 and 36 Cl II-2 patients (female-to-male ratio was 1:1 in each group). 3D digital models (O3DM) with a dedicated programme were used to measure dental arch variables.

RESULTS

Significant differences were observed between the two groups in the mesiodistal widths of some teeth but not in the dental arch widths. The prevalence of 'discrepancy cases' in Anterior Bolton Ratios (ABRs) was 33.33% and 41.67% in Cl II1 and Cl II2 groups, respectively. The mean PAR Index score was 25.36 and 20.82 for Cl II1 and Cl II2 groups, respectively (p=0.009).

CONCLUSIONS

(1) 3D digital models enabled fast, accurate and reliable measurements of dental arch characteristics in patients with Class II malocclusion. (2) Insignificant differences between Cl II1 and Cl II2 patients were observed regarding Bolton's ratios and transverse arch measurements. (3) Sexual dimorphism was observed in mesiodistal tooth widths and in dental arch widths, but not in Bolton's ratios and PAR Index scores.

Permanent mandibular canine(s) impaction: expansion of our understanding

INTRODUCTION

Eruption disturbances, tooth size and specific malocclusions are known to be genetically influenced. The clinical association between these traits may indicate common genetic controls.

OBJECTIVES

A cross-sectional clinical study was designed to test the null hypothesis that the maximum mesiodistal crown diameter (MMD) of maxillary and mandibular central and lateral incisors and the prevalence of various classes of incisor relationships (Class I, II/1, II/2 and III) do not differ between the subjects with and without permanent mandibular canine(s) impaction.

METHODS

Dental models of 43 subjects diagnosed with mandibular canine(s) impaction (Impaction Group - IG) were compared with those of 86 subjects of a control reference sample (Control Group - CG). Independent t-test and chi-square tests were used to determine the association between mandibular canine(s) impaction and the MMD of the incisors and the incisor relationship, respectively. The likelihood of various incisor relationships between the IG and CG were evaluated according to odds ratios.

RESULTS

A fourfold increase (p < 0.0001) in the overall frequency of Class II/2 incisor relationship was observed in the IG when compared to controls.

CONCLUSIONS

The null hypothesis was rejected. Subjects with mandibular canine(s) impaction appeared to be characterised with wider incisors and a remarkably high rate of Class II/2 malocclusion. This information assists the understanding of genetically controlled dental anomalies, which are likely to coexist with mandibular canine(s) impaction.

Improvement in Smoothness of the Chewing Cycle Following Treatment of Anterior Crossbite Malocclusion: A Case Report

This is a report of a case in which improvement in masticatory jaw movement kinematics occurred following orthodontic treatment. A patient who demonstrated a skeletal Class II jaw relationship, with anterior crossbite between the right upper and lower lateral incisors, underwent treatment with an edgewise appliance. The trajectories and smoothness of the patient's jaw-closing movement were compared before and after orthodontic treatment. The correction of the anterior crossbite allowed the patient to consistently close the jaw with wider lateral excursion. Furthermore, after treatment, smoothness of the jaw-closing movements increased significantly, and the velocity profile was characterized as closer to that predicted by the minimum jerk (maximum smoothness) kinematic model. These findings suggest the value of trajectory smoothness (jerk-cost) as an objective indicator of kinematic improvement in gum chewing. In addition, the correction of anterior crossbite is demonstrated to enable the patient to perform smoother jaw-closing movements during chewing.

Class II malocclusion division 1: a new classification method by cephalometric analysis

AIM

The purpose of this study was to analyse the craniofacial and dentofacial skeletal characteristics in untreated subjects with Class II, division 1 malocclusion by mandibular retrusion and to identify different types and their prevalence.

MATERIALS AND METHODS

In 152 subjects with Class II, division 1 malocclusion by mandibular retrusion, the differences were determined by lateral cephalograms analysis of variance and chi-square test, respectively. P<0.05 was considered significant. Seven types of mandibular retrusion were identified: three pure, dimensional, rotational and positional, and four mixed.

RESULTS

All patients showed significant inter-group differences with P between 0.005 and 0.001. The dimensional type was the most common (28.9%) and the rotational-positional type was the rarest (5.9%). The pure dimensional type had the shortest mandibular body; the pure rotational type had larger SN/GoMe and the lowest AOBO; the pure positional type presented the flattest cranial base, high AOBO. In the mixed types, dento-skeletal features changed depending on how the main types assorted.

CONCLUSIONS

Identifying the type of mandibular retrusion is important for differential diagnosis in clinical practice and research.

[A comparative study of the transverse dimensions of the dental arches between Class I dental occlusion and Class II1 and Class II2 malocclusions]

The purpose of this work was to compare transverse dimensions of the maxillary and mandibular arches in the canine and molar region between three groups of patients: the first group had an occlusion in class II division 1, the second one a dental class II division 2 and the third one, a class I bite. Our sample is composed of 94 patients, with an average age of 20 +/- 3 years: 31 patients presented a class I occlusion, 33 a class III1 and 30 cases presented a dental class II2. For this study, we measured, on the maxillary and mandibular dental casts of each patient, the intercanine and intermolar canine (central inter fossa). Comparison of variables was conducted using the variance analysis ANOVA; the selected post-hoc test is the Bonferrroni test. On the basis of our study, we can get the following results: Maxillary intercanine distance is narrower in class II1 compared to class II2 of 2 mm "p < 0.05". Mandibular intercanine distance is narrower in class III1 compared to class II2 of 1, 3 mm "p < 0.05". Maxillary intermolar distance (inter fossa) is narrower in class II1 compared to class I of 2, 2 mm "p < 0.05".

Dermatoglyphics--a marker for malocclusion?

INTRODUCTION

Dermatoglyphics is the study of dermal ridge configurations on palmar and plantar surfaces of hands and feet. Dermal ridges and craniofacial structures are both formed during 6-7th week of intra-uterine life. It is believed that hereditary and environmental factors leading to malocclusion may also cause peculiarities in fingerprint patterns.

OBJECTIVE

To study and assess the relationship between fingerprints and malocclusion among a group of high school children aged 12-16 years in Dharwad, Karnataka, India.

DESIGN

A total of 696 high school children aged 12-16 years were randomly selected. Their fingerprints were recorded using duplicating ink and malocclusion status was clinically assessed using Angle's classification.

RESULTS

Chi-square analysis revealed statistical association between whorl patterns and classes 1 and 2 malocclusion (p < 0.05). However, no overall statistical association was observed between fingerprint patterns and malocclusion (p > 0.05).

CONCLUSION

Dermatoglyphics might be an appropriate marker for malocclusion and further studies are required to elucidate an association between fingerprint patterns and malocclusion.

Dental and alveolar arch asymmetries in normal occlusion and Class II Division 1 and Class II subdivision malocclusions

AIM

To compare the degree of intra- and interarch dentoalveolar asymmetry among patients with a normal occlusion, Class II Division 1 malocclusion, and Class II subdivision malocclusion.

METHODS

The sample comprised dental casts of 150 (72 males [ages 22. 1 +/- 3.11 and 78 females [ages 21.1 +/- 2.1]) normal occlusion subjects, 106 (45 males [ages 17.8 +/- 1.8] and 61 females [ages 16.5 +/- 2.91) Class II Division 1 patients, and 40 (18 males [ages 15.8 +/- 2.8] and 22 females [ages 15.2 +/- 3.3]) Class II subdivision malocclusions. Maxillary and mandibular reference lines were constructed and used for the intraarch asymmetry measurements. Thirty-six width measurements were performed on the dental casts of each subject. Analysis of variance (ANOVA) was used for comparisons of the groups, and Pearson's correlation coefficients were computed to determine the interarch associations.

RESULTS

No statistically significant intra-arch asymmetry was found for maxillary and mandibular dental arch and alveolar width in any of the three groups. All variables were larger on the right side in the normal occlusion subjects. Further, the left side maxillary dental and alveolar arch width measurements were larger in the Class II Division 1 group. None of these differences, however, were statistically significant. In the Class II subdivision group, only the Class II sides' mandibular dental arch measurements were larger (P < .05). Maxillary and mandibular total dental arch and alveolar width dimensions differed among the groups (P < .001). Except for maxillary and mandibular canine alveolar width, opposing interarch dental and alveolar landmarks were significantly correlated with the transverse dimensions.

CONCLUSION

Although some landmarks in the current study showed statistically significant and insignificant differences, the mean arithmetic differences were small, inconsistent, and not likely clinically important.

Arch Widths in Class II-2 Adults Compared to Adults with Class II-1 and Normal Occlusion

Objective: To compare (1) arch widths in adults with Class II division 2 (II-2), Class II division 1 (II-1), and Class I normal occlusions, (2) genders, (3) gender dimorphism, (4) differences between maxillary and mandibular arch widths, and to (5) develop adult norms for arch widths.

Materials and Methods: Subjects were white Americans with no history of orthodontic treatment. Arch width dimensions measured were: intercanine, intermolar, and molar alveolar in both arches. Analysis of variance (ANOVA) and Duncan's test were used to compare groups.

Results: Comparison of pooled genders showed the II-2 group had maxillary arch widths significantly smaller than the normal occlusions and significantly larger than the II-1 group. All groups had similar mandibular intercanine and alveolar widths. The II-2 and II-1 groups had similar mandibular intermolar widths, both significantly smaller than normal occlusions. The II-2 group had a maxillary/mandibular intermolar difference significantly smaller than the normal occlusions, and significantly less negative than the II-1 group. Gender comparisons in two of six widths showed normal and II-2 male subjects were similar, and in six of six widths normal and II-2 female subjects were similar; in five of six widths II-2 and II-1 male and female subjects were similar. Gender dimorphism occurred in five of six widths in normal occlusions, four of six widths in II-2, and one of six widths in II-1.

Conclusions: Arch width dimensions of II-2 subjects were intermediate between normal and II-1 occlusions. In both Class II malocclusions, the process that narrows arch widths was more pronounced in male than in female subjects.

[The Class II subdivision or acquired unilaterally dominant mastication syndrome]

Unilateral disto-occlusion of the molars and the canine teeth, described by Angle as Class II subdivision, is often characterized by asymmetric development of the maxillae in conjunction with a disturbance in physiological mastication. In addition to the unilateral malposition of the molars and the canine, this Class II subdivision condition is routinely accompanied by an ensemble of symptoms that the authors propose regrouping under the designation "children's acquired unilaterally dominant mastication syndrome". They use several clinical examples to illustrate the diagnosis of this condition that they consider to be a syndrome of craniofacial asymmetry.

Class II subdivision malocclusion types and evaluation of their asymmetries

INTRODUCTION

The primary objective of this study was to determine, by means of frontal photographic evaluation, the distribution of the 2 main types of Class II subdivision malocclusions. The secondary objective was to compare the dentoskeletal asymmetries in these 2 types with a group of normal-occlusion subjects by using submentovertex and posteroanterior radiographs.

METHODS

The experimental group included 44 untreated Class II subdivision malocclusion subjects with a mean age of 15.3 years. The control group included 30 subjects with normal occlusions with a mean age of 22.4 years. All had full complements of permanent teeth up to the first molars and had not received orthodontic treatment. Type 1 Class II subdivision malocclusion is coincidence of the maxillary dental midline with the facial midline and deviation of the mandibular midline. Type 2 has the opposite characteristics. The frontal photographs were evaluated subjectively by 2 examiners. In the submentovertex and posteroanterior radiographs, symmetry was assessed by measuring the relative difference in the spatial positions of dentoskeletal landmarks between the right and left sides. Independent t tests were used to compare the dentoskeletal asymmetries of types 1 and 2 with the normal-occlusion group.

RESULTS AND CONCLUSIONS

The results showed that 61.36% had type 1, 18.18% had type 2 Class II subdivision malocclusion, and 20.45% had mixed characteristics. The predominant asymmetric dentoalveolar characteristics of both types of Class II subdivision malocclusions were evident when individually compared with a normal-occlusion control group. There was a tendency for the type 1 subjects to have greater mandibular asymmetry than type 2, as compared with the control group.

[Cephalometric comparisons of the craniofacial characteristics of Class II 1 malocclusions with different vertical types in adolescences]

PURPOSE

To compare the craniofacial characteristics in Class II(1) malocclusions with different vertical types in adolescence.

METHODS

The sample, including 60 males and 60 females, was divided into three groups equally based on their FMA degrees (high-angle group, average-angle group, low-angle group and normal occlusion group). Cephalograms were traced for all the subjects. Data were obtained to perform analysis of variance and LSD multiple range test.

RESULTS

1. The vertical growth of the anterior part of maxilla was greater than the posterior part in the three groups with Class II(1) malocclusion. The vertical dimension of the composite ramus-cranial floor was deficient relative to that of anterior maxilla in the high-angle and average-angle groups, the mandible rotated backward, especially in the high-angle group. In the low-angle group, the vertical dimension of the composite ramus-cranial floor grew excessively relative to that of posterior maxilla. The palatal plane and mandible plane rotated forward and upward. 2. The dentoalveolar characteristics of Class II(1) malocclusion group showed that: U6 tipped distally, the dentoalveolar height of L6 decreased, the functional occlusal plane (FOP) of average-angle group deviated away from the neutral occlusal axis (NOA), and rotated downward. In the high- angle group, the FOP deviated away from the NOA severely. The vertical dentoalveolar heights of U6 were normal. In the low-angle group, the vertical dentoalveolar heights of U6, the dentoalveolar height of L6 decreased, the angle of FOP between NOA showed no significantly difference from normal-occlusion group.

CONCLUSION

There were different craniofacial vertical characteristics of Class II(1) malocclusion with different vertical types in adolescences. Different methods should be used to control the vertical dimensions in different types.

Dental and alveolar arch widths in normal occlusion, class II division 1 and class II division 2

The aim of this study was to compare the transverse dimensions of the dental arches and alveolar arches in the canine, premolar, and molar regions of Class II division 1 and Class II division 2 malocclusion groups with normal occlusion subjects. This study was performed using measurements on dental casts of 150 normal occlusion (mean age: 21.6 +/- 2.6 years), 106 Class II division 1 (mean age: 17.2 +/- 2.4 years), and 108 Class II division 2 (mean age: 18.5 +/- 2.9 years) malocclusion subjects. Independent-samples t-test was applied for comparisons of the groups. These findings indicate that the maxillary interpremolar width, maxillary canine, premolar and molar alveolar widths, and mandibular premolar and molar alveolar widths were significantly narrower in subjects with Class II division 1 malocclusion than in the normal occlusion sample. The maxillary interpremolar width, canine and premolar alveolar widths, and all mandibular alveolar widths were significantly narrower in the Class II division 2 group than in the normal occlusion sample. The mandibular intercanine and interpremolar widths were narrower and the maxillary intermolar width measurement was larger in the Class II division 2 subjects when compared with the Class II division 1 subjects. Maxillary molar teeth in subjects with Class II division 1 malocclusions tend to incline to the buccal to compensate the insufficient alveolar base. For that reason, rapid maxillary expansion rather than slow expansion may be considered before or during the treatment of Class II division 1 patients.

A comparative study of cephalometric and arch width characteristics of Class II division 1 and division 2 malocclusions

The aim of this compound cephalometric and arch-width study was to determine any dental and/or skeletal differences between subjects with Class II division 1 and Class II division 2 malocclusions. The dento-skeletal characteristics of Class II subjects were evaluated using lateral cephalometric radiographs and dental casts of 90 untreated patients. The sample included 46 Class II division 1 patients (19 girls and 27 boys) with a mean age of 15.27 +/- 2.48 years, and 44 Class II division 2 patients (27 girls and 17 boys) with a mean age of 15.95 +/- 3.25 years. The intermolar, interpremolar and intercanine measurements were carried out on study models. The radiographs were digitized and processed using Dolphin Imaging software. In addition to standard descriptive statistical calculations, an independent samples t-test was carried out in order to compare the two groups. The non-parametric Mann-Whitney U test was utilized for the parameters for the data which were not normally distributed. The only statistically significant difference between the groups for the study model measurements was mandibular intercanine width. The cephalometric results revealed that SNB angle was responsible for the skeletal sagittal difference between the two groups. In addition, the Class II division 1 group had higher vertical proportions and the Class II division 2 group a more concave profile with a prominent chin. The sagittal skeletal pattern of Class II division 2 subjects was found to be very similar to the Class I skeletal relationship, with no evidence of any mandibular restriction.

[The Procuste superimpositions: its value in the study of typology and its development during Edgewise Tweed-Merrifield treatment]

By transforming all figures into the same size, the Procruste mathematical superimpositions system allows orthodontists to analyze and compare geometric shapes whose different areas and forms would otherwise have made comparison impossible. Procruste is, accordingly, particularly useful in the study of facial types. In this retrospective study we analyzed the effects exerted by both growth and Edgewise Tweed Merrifield treatment upon changes in patients' typology of three different facial types. One hundred patients with Class II dental malocclusions were divided into three groups of deep bite, normal bite, and open bite. We found no significant statistical difference in the effects of treatment and of growth on modification of "form" of the facial skeleton as seen on profile cephalograms of the three categories. Patients in all the groups showed an average anterior rotation of the mandible.

Assessment of open and incomplete bite correction by incisor overlap and optical density of polyvinyl siloxane bite registration

Open bite (OB) is a generalized term, which could incorporate subgroups that react differently to vertical correction. The objectives of the present study were to detect vertical treatment changes in incomplete bite (IB: inter-incisor overlap with no lower incisor contact with teeth or palate) and OB (no inter-incisor overlap) groups compared with a complete bite (CB: inter-incisor overlap with full lower incisor contact with teeth or palate) control group, to evaluate treatment response of the central and lateral incisors, and to study the vertico-sagittal interaction. Dental casts were taken at three time points, pre-treatment, post-treatment, and after one year of retention, from 54 Class II patients (22 males and 32 females with a mean age of 11 years 6 months) divided into three groups: CB (n = 21), IB (n = 18) and OB (n = 15). Measurements included incisor overlap (mm) and optical density (OD/mm2) of occlusal bite registration made of polyvinl siloxane. Both CB and IB groups demonstrated post-retention bite opening. However, bite opening in the CB group was three times greater than that in the IB group (e.g. lower lateral = -1.42 mm, 118 OD/mm2 versus -0.40 mm, 107 OD/mm2). Conversely, the OB group showed a significant (P < 0.001) bite closure (e.g. lower lateral = 1.30 mm, -377 OD/mm2). Overjet changes affected OD measurements, causing diversity in OD and millimetric measurements of the lateral incisors in the IB group. In conclusion, the OB group demonstrated a significant stable vertical correction; a post-treatment non-contact inter-incisor relationship was determined by a vertico-sagittal relapse; and full compensation of an IB was not possible.

Masticatory performance in children and adolescents with Class I and II malocclusions

It is not fully understood whether masticatory performance is compromised in individuals with the more common forms of malocclusion (i.e. Class I and Class II). The aim of this prospective investigation was to establish the relationships between masticatory performance, malocclusion (type and severity), age, body size and gender, in children and adolescents. A total of 335 individuals were examined at the average ages of 6, 9, 12 and 15 years. Each subject's occlusal status was described by Angle classification and by the Peer Assessment Ratio (PAR) index. Masticatory performance was quantified by the median particle size (MPS) and the broadness of particle distribution using artificial food. Masticatory performance improved significantly with age. The 6-year-old children were less able to break down the food particles (MPS 4.20 mm2) than the 15 year olds (MPS 3.24 mm2). Analysis of covariance showed that age differences in performance are related to an increase in body size. There were statistically significant differences in masticatory performance between children with normal occlusion and those with a Class I malocclusion; no differences were found between normal occlusion and Class II malocclusion. Gender differences did not explain the variation in masticatory performance. It is concluded that occlusal indices are not reliable predictors of masticatory performance. Traditional descriptors of malocclusion type and severity apparently cannot explain most of the variation in masticatory performance in children and adolescents.

Common factors among the major malocclusions

Dental practitioners tend to classify malocclusions in a schematic fashion often forgetting the full possibilities of characteristics related to a particular situation or malocclusion. This paper is designed to clarify and describe the different malocclusions, stressing the multiple faces of Class I in the mixed dentition based on the previous work of Drs. Anderson, Dewey and Sim. The description of all the major malocclusions is included with their facial, skeletal, dental and functional characteristics. Guidelines for diagnosis and treatment planning with a summary of possible difficulties in treatment are also discussed.

Malocclusion and crowding in an orthodontically referred Turkish population

This study was conducted to evaluate malocclusion and crowding in 1356 patients (793 girls, 563 boys) referred to the Department of Orthodontics, Suleyman Demirel University, Turkey. Class I was the most frequently seen malocclusion in this referred Turkish orthodontic population whereas Class II, division 2 was the least frequently seen. Comparison of mean ages of the malocclusion groups indicated statistically significant difference between Class I and Class II, division 1 groups (P < .05). The lowest mean age was present in the Class II, division 1 group. Mild mandibular crowding was the most common finding whereas severe mandibular crowding was seen least frequently in all malocclusion groups. Cross tabulation of maxillary and mandibular crowding indicated that mild maxillary and severe mandibular crowding in the same patient was rarely seen in all types of malocclusions. Moderate maxillary and severe mandibular crowding in the same patient was another rare finding for all malocclusion groups.

Stability of Class II, division 1 treatment with the headgear-activator combination followed by the edgewise appliance

This study assessed the stability of the headgear-activator combination treatment, followed by edgewise mechanotherapy, 5.75 years after treatment. The experimental group consisted of 23 patients who were evaluated during treatment and after treatment. Two compatible control groups consisting of 15 Class II, division 1 patients and 24 normal occlusion individuals were used. This enabled us to evaluate the changes during treatment and after treatment, respectively. Results showed that the anteroposterior dentoalveolar changes and the maxillary and the mandibular positions remained stable in the long term. However, there was a slight relapse of the maxillomandibular relationship probably because the maxilla resumed its normal development and the mandibular growth rate was smaller than in the control group. The overbite demonstrated a statistically significant relapse that was directly proportional to the amount of its correction. There were low but significant inverse correlations between the changes in Go-Gn during and after treatment. These included the uprighting of the maxillary incisors, labial tipping of the mandibular incisors, and the amount of molar relationship correction during treatment and their stability. Active retention time, length of posttreatment period, initial Class II malocclusion severity (ANB and Wits), and initial molar relationship did not present any correlation with molar relationship and overjet relapse. However, the initial overjet presented a low but statistically significant correlation with molar relationship relapse and overjet relapse.

A new approach of assessing sagittal discrepancies: the Beta angle

An accurate anteroposterior measurement of jaw relationships is critically important in orthodontic diagnosis and treatment planning. The angular and linear measurements that have been proposed can be inaccurate because they depend on various factors. The purpose of this study was to establish a new cephalometric measurement, named the Beta angle, to assess the sagittal jaw relationship with accuracy and reproducibility. This angle uses 3 skeletal landmarks-point A, point B, and the apparent axis of the condyle-to measure an angle that indicates the severity and the type of skeletal dysplasia in the sagittal dimension. Seventy-six pretreatment cephalometric radiographs of white patients were selected on the basis of 4 criteria that indicate a normal Class I skeletal pattern; the mean and the SD for the Beta angle were calculated. This group was compared with Class II and Class III skeletal pattern groups. After using the 1-way analysis of variance and the Newman-Keuls test and running receiver-operating-characteristics curves, we obtained results that showed that a patient with a Beta angle between 27 degrees and 35 degrees can be considered to have a Class I skeletal pattern. A more acute Beta angle indicates a Class II skeletal pattern, and a more obtuse Beta angle indicates a Class III skeletal pattern.

Treatment outcomes of growing Class II Division 1 patients with varying degrees of anteroposterior and vertical dysplasias, Part 2. Profile silhouette evaluation

The purpose of this study was to evaluate pretreatment and posttreatment soft tissue profiles of 4 groups of growing Class II Division 1 patients treated with fixed orthodontic appliances and headgear. One hundred patients were grouped according to the severity of their initial retrognathia and vertical skeletal status. Standardized pretreatment and posttreatment profile silhouettes of each patient were randomized and projected for scoring by panels of lay persons and orthodontic residents. Statistical analysis consisting of nonparametric procedures showed that (1) as the initial skeletal discrepancies between the 4 groups worsened, the initial profiles were judged to be more unattractive (P <.001); (2) there was no perceived difference in the final profiles between the 4 groups; and (3) significantly greater improvement was measured for those with greater initial skeletal discrepancies (P <.05). This study demonstrated that, with appropriate and timely treatment with fixed orthodontic appliances and headgear, growing Class II Division 1 patients can undergo significant profile improvement, and, on average, even those more severely affected can achieve profile improvement so that they can be judged as attractive as those initially less severely affected.

Class II treatment success rate in 2- and 4-premolar extraction protocols

This study compared the occlusal success rate of Class II orthodontic treatment results with either 2- or 4-premolar extraction protocols. Group 1 comprised dental study models of 81 patients treated with 2 premolar extractions, and group 2 comprised dental study models of 50 patients treated with 4 premolar extractions. The initial mean ages of the groups were 13.9 and 12.9 years, respectively. Grainger's treatment priority index (TPI) was used to assess the initial and final occlusal status of each patient. Individual variables, such as maxillary canine anteroposterior positioning, overjet, and overbite improvements were also evaluated. Independent t tests were used to compare the variables at the pretreatment and posttreatment stages and their improvement between the groups. The results showed a statistically significant difference in most of the variables and in their improvement at the end of treatment between the groups. The variables showed a better dental relationship in group 1, and the improvements in group 1 were larger than in group 2. Treatment of Class II malocclusion with 2 premolar extractions gives a better occlusal success rate than treatment with 4 premolar extractions.

Treatment outcomes of growing Class II Division 1 patients with varying degrees of anteroposterior and vertical dysplasias, Part 1. Cephalometrics

The purpose of this retrospective study was to evaluate the differences in orthodontic treatment outcomes for 5 groups of growing Class II Division 1 patients with various anteroposterior and vertical skeletal dysplasias. Pretreatment and posttreatment cephalograms of 100 patients were evaluated for soft and hard tissue treatment effects and differences between groups. Changes from pretreatment to posttreatment differed between groups in correction of overjet and change in ANB angle (P <.05). Those with the largest skeletal dysplasias had the greatest skeletal correction but also retained the largest ANB angles posttreatment. Additional correction was achieved through dentoalveolar change with the greatest uprighting of maxillary incisors occurring in patients who initially were the most severely affected (P <.05); this effect was accompanied by an increase in nasolabial angle. All groups had similar changes in mandibular incisor positions, and final positions of the mandibular incisors did not differ between groups. Compared with norms, Z angles and facial contour angles showed discrimination between the most and least severely affected patients based on combined anteroposterior and vertical dysplasias (P <.05). However, there were no clear-cut divisions between the groups, especially with regard to soft tissue cephalometric outcomes. Further evaluation of profile esthetics follows in Part 2. We conclude that conventional orthodontic therapy successfully corrects Class II Division 1 malocclusions in growing patients through a combination of skeletal and dentoalveolar changes, with the greatest changes occurring in patients who initially have the most severe skeletal dysplasias.

Unilateral Angle II in functional lateralities

The aim of this study was to explore unilateral Angle II-type malocclusion prevalences in functionally true right-sided (TRS) and non-right-sided (NRS) children having one or more left-sided functions (eye, hand, foot). A half cusp sagittal relationship of the upper and lower M1 and Dm2 was determined on dental casts of 1423 young American black and white children in a cross-sectional sample with the mean age of 8.5 years (range 6-12 years). Hand, foot and eye preferences were recorded at the age of 4 years during the Collaborative Perinatal Study. The prevalences of symmetric bilateral Angle I and II and asymmetric unilateral Angle II right and Angle II left cases were compared between TRS and NRS children using Chi-square analysis. In general, unilateral Angle II right occurred in 9 per cent of the population and Angle II left in 6.5 per cent. In moderate non-right sideness (two-thirds of left dominant functions), these proportions were 17 and 3 per cent, respectively, and in true right sidedness 8 and 6 per cent, respectively. TRS subjects were more symmetric (bilateral Angle I or II in 85 per cent of cases) than NRS children (80 per cent), and the differences were statistically significant (P < 0.02). These results highlight the anatomical relationships of structures supporting the occlusion and the symmetry/asymmetry of the neurocranium, cranial base, masticatory apparatus, and probably also the sidedness and the growth-stimulating effect of lateralized jaw function. Based on the results and considering earlier observations on brain asymmetry in functional lateralities, it can be hypothesized that a normal symmetric sagittal occlusal relationship is based on unilateral sagittal compensatory growth to maintain optimal bite, challenging early preventive orthodontic treatment in suspect unilateral Angle II cases.

Crown-root shape of the permanent maxillary central incisor

This study aimed to determine whether the lateral cephalometric crown-root shape differs among the permanent maxillary central incisor in Class I, Class II division 1, Class II division 2 and Class III malocclusions and to identify the nature of any differences. Of the 499 lateral cephalograms recorded at a university orthodontic clinic during 2001, 361 satisfied the inclusion criteria. Sixty cephalograms were selected from the four malocclusion groups and were digitized in random order. The configurations of the 10 landmarks characterizing the crown-root shape of the permanent maxillary central incisor were then optimally superimposed using Procrustes algorithms. Discriminant analysis of the principal components of shape determined the incisor shape differences between the malocclusion groups. The crown-root shape of the permanent maxillary central incisor did not differ significantly among the Class I, Class II division 1, and Class III groups (P > .05); however, the crown-root shape of the Class II division 2 permanent maxillary central incisor was significantly different (P < .001) from that of the Class 1, Class II division 1 and Class III. The shape discrimination involved axial bending of the Class II division 2 incisors. Principal components 1, 2, and 3 accounted for 63% of the Class II division 2 incisor shape variance, encompassing a shorter root, a longer crown, and axial bending of the incisor, in addition to a reduced labiopalatal thickness. These shape features could precipitate the development of a deep overbite in Class II division 2 malocclusion and may limit the amount of palatal root torque during fixed appliance therapy.

The pattern of malocclusion among orthodontic patients seen in Dental Centre, University College Hospital, Ibadan, Nigeria

The aim of this study was to analyse the malocclusion pattern among patients who presented for treatment in the Orthodontic Unit of the Dental Centre, University College Hospital, Ibadan, as baseline data for proper treatment planning, teaching and further research. A total of 289 subjects aged 5-34 years with mean age of 10.6 +/- 1.5 (S.D.) years were seen. Angle's classification of molar relationships among those seen is as follows: class I - 76.5%, Class II - 15.5% and Class III - 8.0%. There was increased overjet in 16.2% of the patients, reduced overjet in 0.7% while 2.1% had reversed overjet. Other occlusal abnormalities included: increased overbite (3.8%), reduced overbite (1.4%); anterior open bite (5.2%; crossbite (8.4%) and scissorsbite (0.6%). Crowding, spacing and retained primary incisors constituted 29.7%, 1.4% and 40.1%, respectively. Delayed eruption of canine (1.0%), Bimaxillary protrusion (0.7%), incompetent lips (0.7%), supernumerary teeth (0.7%) malformed tooth (0.3%), mandibular deviation on closure (1.0%) and oral habits (4.5%) were other forms of malocclusion diagnosed. Males were found to have significantly more of classes II and III molar relationships than females (P < 0.05). Occurrence of retained primary teeth as well as overjet deviations from normal were significantly higher in females (P < 0.05). No significant sex differences were found in the other occlusal disorders (P > 0.05): The findings were comparable with previous epidemiological surveys in other parts of the country.

Readiness for orthognathic surgery: a survey of practitioner opinion

The purpose of this study was to determine if a general consensus exists among orthodontists regarding the features of an adequate presurgical setup. A questionnaire was developed to assess the importance of 12 criteria for surgical readiness. Each criterion was rated on a 5-point scale (1 = Unimportant, 5 = Critical). This questionnaire was sent to 104 randomly selected, board-certified orthodontists in the United States and Puerto Rico. Usable questionnaires were returned by 57 respondents (55% response rate). The highest and most consistent ratings were given for Arch Compatibility in the transverse dimension (mean = 4.66, SD = 0.55), Crossbite (mean = 4.57, SD = 0.63), and Torque of the Anterior Teeth (mean = 4.38, SD = 0.73). Further analysis showed a correlation between surgical experience of the orthodontist and a higher rating of importance for Torque of the Mandibular Teeth (Spearman r = 0.38), Torque of the Maxillary Teeth (Spearman r = 0.37), and Torque of the Anterior Teeth (Spearman r = 0.28). These results suggest that as orthodontists gain surgical experience, they attribute more importance to correcting the torque of the teeth. Also, the relatively large differences in opinion regarding presurgery orthodontic setup support a need for further research and/or educational effort regarding what criteria are important before surgery.

A multicenter interracial study of facial appearance. Part 2: A comparison of intraoral parameters

PURPOSE

This article compares interracial or gender differences of six intraoral dental parameters among six racial groups (African American, Caucasian, Chinese, Hispanic, Japanese, and Korean).

MATERIALS AND METHODS

The same 253 patients participating in part 1 were included in this portion of the study to evaluate six intraoral parameters. The data were collected and analyzed using a one-way analysis of variance, followed by the Tukey-Kramer test for honestly significant difference when statistically significant differences were found (P < .05).

RESULTS

Women displayed significantly more gingival tissue in four of the six races, and African Americans displayed significantly more gingival tissue than any other race. Women had significantly more missing teeth than men in three of the six races studied. Japanese subjects had significantly fewer missing teeth and smaller maxillary central incisors than all other groups except Caucasians. Women had significantly narrower maxillary central incisors in three of the races. There was a significantly higher prevalence of Angle Class III relationships in Chinese subjects. The Japanese had significantly more Class II molar relationships than other races.

CONCLUSION

Racial and gender differences were found in gingival tissue display, the number of missing teeth, maxillary right central incisor crown width, and Angle molar classification, but not in the amount of vertical or horizontal overlap of the anterior teeth.

Class II division 1 malocclusions: the subdivision problem

The purpose of this study was to determine the frequency of occurrence of subdivisions, in Class II division 1 malocclusions. Sixty patients seeking orthodontic treatment at the dental college of King Saud University were selected. The results revealed that 45% of Class II division 1 patients examined had subdivisions. The most commonly affected side was the right (66.7%). Mandibular shift upon closure was noted in 36% of the subdivision cases. Mandibular asymmetry was noted in 62.6% of the patients. It can be concluded from this study that subdivisions are a frequent finding in Class II division 1 malocclusions. Appropriate diagnosis of these cases should be done early in the mixed dentition phase, to avoid developing dental or skeletal asymmetries that can persist throughout adulthood.

Mandibular advancement surgery in high-angle and low-angle class II patients: different long-term skeletal responses

The objective of this cephalometric study was to compare skeletal stability and the time course of postoperative changes in high-angle and low-angle Class II patients after mandibular advancement surgery. The subjects were 61 consecutive mandibular retrognathism patients whose treatment included bilateral sagittal split osteotomy and rigid fixation. The patients were divided according to the preoperative mandibular plane angle; the 20 patients with the lowest mandibular plane angle (20.8 degrees +/- 4.9 degrees ) constituted the low-angle group, while the 20 cases with the highest mandibular plane angle (43.0 degrees +/- 4.0 degrees ) represented the high-angle group. Lateral cephalograms were taken on 6 occasions: immediately before surgery, immediately after surgery, 2 and 6 months after surgery, and 1 and 3 years after surgery. Results demonstrated that the high-angle and low-angle groups had different patterns of surgical and postoperative changes. High-angle patients were associated with both a higher frequency and a greater magnitude of horizontal relapse. While 95% of the total relapse took place during the first 2 months after surgery in the low-angle group, high-angle patients demonstrated a more continuous relapse pattern, with a significant proportion (38%) occurring late in the follow-up period. Possible reasons for the different postsurgical response are discussed.

Treatment of a Class II Division 2 malocclusion with space reopening for a single-tooth implant

This case report describes the treatment of an adolescent girl with a skeletal Class II Division 2 malocclusion and impinging overbite. One of 2 previously extracted premolars had to be replaced by a single-tooth implant after adequate space reopening. An optimal overbite-overjet relationship was achieved through significant intrusion and proclination of maxillary and mandibular incisors. A horizontally impacted mandibular second molar was repositioned to ensure a 2-molar arch integrity. Resolution of the gingival smile line and favorable facial changes were also obtained.

[Proposal for a classification of Class II Division 1: contribution of Delaire's analysis]

Class II division 1 dental malocclusions are present in various forms depending on the site, direction and degree of discrepancy between the arches. The ability to recognize the origin of the malocclusion is essential to decide how, and when it is necessary to treat. In this study, the Delaire's analysis was performed for 111 individuals with a Class II division I malocclusion; a classification of these cases is proposed, according to the presence or the absence of a skeletal discrepancy. In 87% of the cases, a Class II division 1 dental malocclusion was associated with a Class II skeletal discrepancy (50% maxillary prognathism, 23.5% normal maxillary relationship and 13.5% maxillary retrognathism). The lines of the cranial base, the shape and size of the mandible varied considerably. In only 6% of cases, the dental malocclusion was associated with a skeletal Class I relationship, and in 7% of cases with a Class III relationship: it was often related to retruded mandibular teeth. It was shown that Class II division 1 dental malocclusions may result from differing causes: therefore, the identification of their etiology seems essential to provide the best possible treatment, at the right period in time.

Classification of occlusion reconsidered

Katz's quantitative modification of Angle's occlusion classification has been found to have a high intra- and inter-examiner agreement among orthodontists. In the present study an attempt was made to introduce a 'combined' system comprising Katz's modification and overjet/overbite millimetric measurements in order to attain a more meaningful and complete classification of malocclusion than is presently available. A group of 32 raters (16 orthodontists and 16 senior-year students) examined 14 study models twice, with an interval of at least 1 month between examinations. In total, 448 x 2 determinations were performed. The percentage agreement of the Angle, the modified and the 'combined' systems, as well as the performance of the orthodontists versus the students were compared using the paired t-test. The percentage agreement obtained by both orthodontists and students was highest for Katz's modification and lowest for Angle's method. The overjet/overbite measurements affected the agreement in Katz's modified technique. The orthodontists surpassed the students with respect to Angle's method (P = 0.025), whereas no statistically significant difference existed between orthodontists and students regarding Katz's modification or the 'combined' system. It is concluded that in view of the relatively low agreement in the 'combined' method, it cannot be recommended for clinical application. The Katz's modified method, on the other hand, may be a helpful supplement to Angle's classification.

Rapid palatal expansion in treatment of Class II malocclusions

A technique which combines the use of rapid maxillary expansion and fixed appliance in growing patients, is presented. The treatment in three patients with Class II division 1 malocclusion and different skeletal patterns is described, and relative advantages highlighted.

[Orthodontic preparation for orthognathic surgery. Various specific points]

Orthodontic preparation before orthognatic surgery must straighten teeth alignment to enable correct adaptation of the upper and lower arches. It must also rectify dento-alveolar abnormalities partially responsible for the dysmorphosis and which can hinder smooth articulation of the bones. Thus before and after the operation, the orthodontist will have to prepare and monitor the surgical splints used in posterior deficiencies.

The differences in the chronology and calcification of second molars between angle Class III and Class II occlusions in Japanese children

The purpose of this study was to examine the differences in the times of eruption and calcification of the permanent dentition between skeletal class III and class II groups. (And also to examine the relationship between the time of eruption and the type of malocclusion) Fifty-three children, ages seven to ten years, were selected. Of these, twenty-six children (twelve boys and fourteen girls) were Angle class III with minus ANB and twenty-seven children (eleven boys and sixteen girls) were Angle class II with five or more ANB. Panoramic radiographs and cephalometric radiographs were used. The panoramic radiographs showed that the calcification of the maxillary second molars in class II were earlier than in class III using Nolla's classification. There was no statistically significant difference, however, for mean values of calcification stages, using Nolla's classification, between boys and girls. The cephalometric and panoramic radiographs showed that the times of eruption and calcification were earlier in the maxillary second molars than in the mandibular second molars for class II. In contrast, the times of eruption and calcification were earlier in the mandibular second molars than in the maxillary second molars for class III. The times of eruption and calcification of the maxillary molars were significantly related to the length of the ANS-PNS. The longer the ANS-PNS, the earlier were the times of eruption and calcification. There was a significant relationship between the ANB angle and the time of eruption, as well as the ANB angle and calcification. The larger ANB had earlier calcification and chronology of maxillary second molars.

Herbst appliance treatment of Class II, division 2 malocclusions

The purpose of this investigation was to analyze quantitatively the sagittal skeletal and dental changes that contribute to occlusal correction in Herbst treatment of 14 Class II, Division 2 malocclusions. Forty Class II, Division 1 Herbst subjects were used for comparison. Lateral head films from before and after Herbst treatment were analyzed, according to the method of Pancherz. The results revealed that all patients were treated to Class I or overcorrected Class I molar and edge-to-edge incisor relationships. The maxillary and mandibular skeletal changes were similar in both examination groups. In the Class II, Division 2 subjects, sagittal molar and overjet corrections amounted to an average of 5.9 mm and 3.1 mm, respectively. When comparing the Class II, Division 2 with the Class II, Division 1 subjects, overjet correction was, for natural reasons, significantly larger (p < 0.001) in the Class II, Division 1 subjects. In the subjects with Class II, Division 2 malocclusions, the upper incisors were proclined (mean = 3.0 mm), whereas in the subjects with Class II, Division 1 malocclusions, the incisors were retroclined (mean = 2.3 mm). The lower incisors were on the average proclined more (p < 0.05) in the Class II, Division 2 subjects (mean = 3.4 mm) than in the Class II, Division 1 subjects (mean = 2.4 mm). For sagittal molar correction, no differences in tooth movements were seen between the two malocclusions groups. In conclusion, it was found that the Herbst appliance is most effective in the therapy of Class II, Division 2 malocclusions. Proclination of the lower incisors during treatment (anchorage loss) is advantageous in this type of malocclusion.

Comparison between cephalometric classification methods for sagittal jaw relationships

The present study evaluated how 2 widely used cephalometric sagittal analyses, ANB angle and WITS appraisal, classify skeletal classes I, II, and III in a random selection of 497 Finnish boys aged 4-20 years. This distribution was also compared with the visual inspection of cephalometric structures judged by 2 university instructors in orthodontics. The results showed remarkable differences and even sparked controversy concerning classification of the sagittal jaw relationships. The ANB angle and the WITS appraisal emphasized the role of class II based on a failure to distinguish the proportion of class I. The low-angle influence skewed the distribution of the ANB pattern in the class III direction, and the WITS pattern, conversely, towards class II. High- or low-angle influence had only minor effects on the visual inspection of cephalometric structures. This cross-sectional study showed an age-related decreasing mean value for the ANB angle and increasing mean value for the WITS appraisal, thus explaining the remarkable difference in the distribution of sagittal classes. However, the findings of age-related changes makes the use of the fixed norms questionable. For extreme or controversial cephalometric interpretations, visual inspection provides an essential aid in diagnosis and skeletal classification.

Cephalometric characteristics of Class II division 1 and Class II division 2 malocclusions: a comparative study in children

A comparison of dentoskeletal morphology in 347 Class II division 1 and 156 Class II division 2 malocclusions was performed using lateral cephalometric radiographs. Children at the ages of 8-10 years and 11-13 years were evaluated. The results of the study revealed broad variations in the variables analyzed. Skeletal Class II and Class III as well as hypo- and hyperdivergent maxillary/mandibular jaw base relationships were seen in both malocclusion samples. Noteworthy was the high frequency of cases with mandibular retrusion (Class II division 1 sample: 48% of the younger and 29% of the older subjects; Class II division 2 sample: 48% of the younger and 49% of the older subjects) and a short lower face (97%-100%). In conclusion it can be said that, except for the position of the maxillary incisors, no basic difference in dentoskeletal morphology exists between Class II division 1 and Class II division 2 malocclusions.

Orthodontic treatment planning by general dental practitioners

A group of 30 general dental practitioners were asked to plan treatment for a series of 10 Class II division 1 malocclusions of graded severity. The results were assessed against a gold standard provided by three consultants. Only 14 per cent of practitioner treatment plans agreed with the gold standard and agreement was worst for those cases requiring the use of headgear. When consultants and General Dental Practitioners (GDPs) were asked whether a case should be referred for advice before the GDP began treatment, 64 per cent of GDP decisions agreed with those of the consultants. On 13 per cent of occasions, however, the GDP would have initiated incorrect treatment without seeking consultant advice.