Similar Malocclusions Research Articles

Staging of Orthodontic Tooth Movement in Clear Aligner Treatment: Macro-Staging and Micro-Staging—A Narrative Review

Abstract: Aims: This review aims to analyze the multiple factors affecting the staging of the orthodontic tooth movement during clear aligner treatment and to provide an efficient work methodology in this regard during digital treatment planning. Materials and Methods: A literature search was conducted on electronic databases (Pubmed, Scopus, Google Scholar and CNKI). The results of the present study have been divided into several sections: (1) definition and concept of staging, (2) basic principles of clear aligners, (3) macro-staging, (4) micro-staging, and (5) limitations. Results: The terminology of macro-staging and micro-staging proposed in this paper aims to be a first step towards a more detailed analysis of staging. The macro-staging constitutes the general biomechanics of movements that need to be prioritized to meet the objectives of the treatment plan. It provides a comprehensive view of the movements occurring in each dental arch. The micro-staging constitutes the biomechanics of movements for each individual tooth. This involves studying the movements in the different planes of space in which each tooth is programmed, deciding if they are compatible, and having strategies to create space to avoid lack of expression. Conclusions: Further studies should focus on exploring different staging approaches to address similar malocclusions to determine which are the most effective and applicable to clinical practice.

Short- and Long-Term Effects of Maxillary Expander with Tongue Crib in Growing Open-Bite and Skeletal Class II Patients: A Retrospective Study.

The purpose of this study was to evaluate short- and long-term changes in growing patients with Class II malocclusion and open bite after rapid maxillary expansion (RME). A retrospective cohort study was conducted with 16 growing patients with open-bite malocclusion enrolled in a group treated with a rapid maxillary expander (RME) with a crib (TG), and 16 untreated patients with similar malocclusion in the control group (CG). Cephalograms were recorded before starting the treatment (T0), at the end of the latency phase (T1), and before the fixed therapy (T2) in order to analyze skeletal and dental changes in vertical, transversal, and sagittal relationships. Statistical analysis was performed with α = 0.05 as level of significance. At the end of the active expansion (T1), all subjects in the TG showed a corrected overbite with a statistically significant difference compared to the CG (p > 0.05). A significant decrease in jaw divergence was found in the TG compared to the CG (p < 0.05). At T2, all treated patients maintained a correct overbite. Statistical analysis revealed a significant decrease in maxillary, mandibular, and intermaxillary divergence in the TG compared to the CG (p < 0.05). This protocol could be effective in growing open-bite patients, showing a long-term decrease in facial divergence. The fixed crib allowed to normalize myofunctional activity.

Evaluation of Hard Tissue, Soft Tissue and Airway Changes Post Twin Block Therapy: An In-vitro Study

Introduction: Aesthetic improvement happens to be one of the main reasons for seeking orthodontic treatment in patients with Angle’s Class II malocclusion. Prognathic maxilla, retrognathic mandible or a combination of both are the main aetiological factors for this malocclusion. Growth modification treatment with different methods can be performed in order to correct skeletal class II malocclusion. Appliance therapy to correct similar malocclusions should immaculately be directed towards addressing the dentoskeletal discord, in order to gain a favourable facial aesthetic result. Aim: To assess the effects of twin block on mandibular length, soft tissue profile and Oropharyngeal Airway (OAW) dimensions in skeletal class II malocclusion patients. Materials and Methods: An in-vitro study was carried out in the Department of Paedodontics at Sardar Patel Postgraduate Institute of Dental and Medical Sciences, Lucknow from June 2018 to March 2021. Study was done on lateral cephalograms of 15 growing children with Angle’s Class II Division 1 malocclusion in the age group of 9-12 years, who had undergone functional appliance therapy with twin block appliance. Standardised lateral cephalograms were evaluated at pretreatment (0 month) and postactive phase of twin-block therapy (9-12 months). Selected hard tissue, soft tissue and airway landmarks were marked and traced to evaluate hard tissue, soft tissue and airway changes. The data was analysed using statistical package for social sciences (SPSS) version 21. Results: There was a statistically significant increase in effective mandibular length (Condyle-Gnathion) and mandibular base length Gonion-Pogonion (Go-Pog) values (p&lt;0.001). Significant decrease in the facial convexity Glabella- Soft tissue Nasion (G-Sn) Soft tissue Nasion- Soft tissue Pogonion (Sn-Pog) was observed and airway dimensions showed significant increase after twin block therapy. Conclusion: Correction of Class II malocclusion by twin block appliance resulted in significant cephalometric changes in the hard tissue profile (increase in mandibular length), together with clinically favourable soft tissue changes and OAW dimensions.

Postural characteristics of patients with unilateral cleft lip, alveolar ridge and palate

Relevance. Treatment of patients with cleft lip and palate requires a comprehensive approach in treatment, and analysis of the vertebral column state reveals the need to include orthopedic rehabilitation in the therapy algorithm. The purpose of the study is to assess the posture disorders and spinal deformities in patients 5-12 years old with cleft of the upper lip, alveolar process and palate and compare with posture disorders in patients with mesial occlusion.Materials and methods. The study involved 26 patients (8 girls, 18 boys) with unilateral cleft lip and palate and 24 children (9 girls, 15 boys) with mesial occlusion, aged 5-12 years, whose posture was studied by the optical topographic imaging technique. The results of "sagittal analysis", "lateral analysis", and "horizontal analysis" were received. The examination resulted in the allocation of several groups according to the posture health, which was determined based on the worst diagnosis made on three planes of the spinal column examination: I-H – health group I – healthy; I-S – health group I – subnormal (1-2 stage scoliosis); II-PD – health group II – posture disorder; II-SD – health group II – spinal deformity (1-2 stage scoliosis and other spinal deformities); III – health group III – moderate and severe spinal deformities. Statistical data was processed using the "data analysis" function of the KOMOT program itself and the Microsoft Excel program.Results. Patients with cleft lip, alveolar ridge and palate demonstrated musculoskeletal disorders more frequently than children with similar malocclusion, especially in a frontal and sagittal plane: 72% of the main group and 50% of the comparison group exhibited stage-1 scoliosis, round-concave back, enhancement of physiologic curves were also 14% higher in the main group.100% of the examined children of the main group revealed postural disorders in the coronal plane, 61% – in the horizontal plane and 89% – in the sagittal plane.Conclusions. The study evidenced that patients with cleft lip, alveolar process, and palate have significantly more musculoskeletal disorders than children, who have a similar malocclusion. Orthopaedic treatment should be included in the rehabilitation of children with cleft lip, alveolar ridge and palate.

Relative Frequency of OCD in People with Malocclusion Class I Requiring Orthodontic Treatment

Introduction: The Malocclusion or misalignment of teeth affects not only oral function but also facial esthetics and the psychological well-being of patients. In addition, obsessive-compulsive disorder is a psychological disorder associated with anxiety involving 2-2.5% of the population during their life. This study aimed to assess the severity of obsessive-compulsive disorder in patients having class I malocclusion with crowding. Materials &amp; Methods: In this case-control trial, Using the Yale-Brown questionnaire, female patients with 18-22 years old of ages having class I crowding malocclusion and referring to orthodontic department of Azad Dental school enrolled in the trial as the case group (n = 60). The participants with similar malocclusion without reference for orthodontic treatments followed up as the control group (n = 60). The obtained data by Yale-Brown questionnaire classified the obsessive-compulsive disorder in the participants into four groups of mild, fairly mild, moderate and severe levels. The results of the two groups were analyzed using the Chi-square test (p value &lt; 0.05). Results: In malocclusion patients referring for orthodontic treatments, 19 (31.7%) had mild OCD; 7 (11.7%) had fairly mild OCD; 23 (38.3%) had moderate OCD and 11 (18.3%) showed severe OCD. These values were 28 (46.7%); 12 (20.0%); 15 (25.0%) and 5 (8.3%) for malocclusion patients not referring for orthodontic patients respectively. No significant differences were found among 2 groups regarding severity of OCD (p value = 0.07). Conclusion: In terms of the severity of OCD, there were no significant variations between malocclusion patients with and without referring for orthodontic treatments.

Three-dimensional cone beam computed tomography analysis of temporomandibular joint response to the Twin-block functional appliance.

ObjectiveTo propose a three-dimensional (3D) method for evaluating temporomandibular joint (TMJ) changes during Twin-block treatment.MethodsSeventeen patients with Class II division 1 malocclusion treated using Twin-block and nine untreated patients with a similar malocclusion were included in this research. We collected their cone beam computed tomography (CBCT) data from before and 8 months after treatment. Segmentations were constructed using ITK-SNAP. Condylar volume and superficial area were measured using 3D Slicer. The 3D landmarks were identified on CBCT images by using Dolphin software to assess the condylar positional relationship. 3D models of the mandible and glenoid fossa of the patients were constructed and registered via voxel-based superimposition using 3D Slicer. Thereafter, skeletal changes could be visualized using 3DMeshMetric in any direction of the superimposition on a color-coded map. All the superimpositions were measured using the same scale on the distance color-coded map, in which red color represents overgrowth and blue color represents resorption.ResultsSignificant differences were observed in condylar volume, superficial area, and condylar position in both groups after 8 months. Compared with the control group (CG), the Twin-block group exhibited more obvious condyle-fossa modifications and joint positional changes. Moreover, on the color-coded map, more obvious condyle-fossa modifications could be observed in the posterior and superior directions in the Twin-block group than in the CG.ConclusionsWe successfully established a 3D method for measuring and evaluating TMJ changes caused by Twin-block treatment. The treatment produced a larger condylar size and caused condylar positional changes.

Effects of the cervical headgear in growing Angle Class II malocclusion patients: a prospective study.

ABSTRACT Objective: Evaluate dental and skeletal changes resulting from the exclusive use of the cervical headgear for 15 ± 4 months in the treatment of patients with Class II division 1 malocclusion. Methods: Differences between the beginning (T1) and immediately after the end of the therapy (T2) with the cervical headgear in growing patients (Experimental Group, EG, n = 23) were examined and compared, during compatible periods, with those presented by a group of untreated individuals (Control Group, CG, n =22) with similar malocclusions and chronological age. The cephalometric variables evaluated were: ANB, GoGn.SN, AO-BO, S'-ANS, S'-A, S'-B, S'-Pog and S'-U6 (maxillary first molar). The Shapiro-Wilk and Levene tests were used to evaluate the results. Results: Significant differences were found relative to the ANB, S'-U6, AO-BO, S'-ANS, S'-A, S'-B and S'-Pog variables between T1 and T2 when comparing both groups. No statistically significant variation was found regarding the GoGn.SN angle.Conclusions: The use of cervical headgear promoted distal movement of the maxillary first molars and restricted the anterior displacement of the maxilla, without significantly affecting the GoGn.SN angle.

Corticision: A Flapless Procedure to Accelerate Tooth Movement.

Orthodontic tooth movement results from applied forces to the teeth evoking cellular responses in the teeth and their surrounding tissues, including the periodontal ligament, alveolar bone and gingiva. It is advantageous for the orthodontist to be well informed of the detailed process of the biological events that unfold during tooth movement, since some of these details may differ from one person to another due to biological differences such as periodontal metabolism or alveolar bone density. This led us to emphasize that orthodontics is a field of endeavor where the integration of mechanics and biology is materialized, and to affirm the fact that tooth movement is conducted in individual human beings, each composed of a unique and intricate physiological system. Biological variations may be the foundation of the differences that are frequently observed in the outcomes of orthodontic treatment in particular with reference to treatment duration between patients with similar malocclusions and who were treated identically. A wide diversity of clinical trials has been carried out to control the tissue resistance to facilitate orthodontic tooth movement, which involves biomechanical, pharmaceutical, surgical, electrical regimens or tissue engineering technology. The term 'Corticision' is a neologism which indicates 'cortical bone incision'. It is a minimally invasive periodontal procedure without flap elevation, thus accelerating tooth movement with an enhanced turnover rate of the surrounding structures. This chapter introduces the technical procedure, and the biological background of how such a minor surgical procedure can receive the accelerated tooth movement with impunity and thereby shorten the duration of treatment.

Awareness of orthodontic treatment need and perceptions of dental attractiveness among school children

Aim: The study aimed at assessing awareness about their own orthodontic treatment need and their perceptions about the dental attractiveness in school children. Subjects and Methods: The random sample of 200 school children (126 boys, 74 girls), aged 9-16 years was selected and categorized into eight different groups according to their occlusion after the dental check-up. Their own orthodontic treatment need and perception of the dental attractiveness was assessed by using questionnaire and was scored by showing eight intraoral frontal photographs and assessing their responses. Statistical Analysis Used: Chi-square test. Results: About 86% of school children considered well-aligned teeth important for overall facial appearance. School children scored photos having severe crowding (95.5%), highly placed canine (86.5%), and Class II Division 2 (70.5%) as most unattractive. 69.5% students did not feel the need of orthodontic treatment and 14.5% students did not know about orthodontic treatment. Conclusion: The study concluded that after showing positive perception toward dental attractiveness, when similar malocclusion was observed in them, they did not feel the need for orthodontic treatment due to lack of awareness. The study emphasizes the need to increase awareness especially among school children about different malocclusion and importance of orthodontic treatment as it is advantageous in preventing further complications.

A psychological study of people who seek orthodontic treatment: Comparison with untreated controls

Objective Improvement in appearance is an important motivation for orthodontic treatment; nevertheless, not all patients with malocclusion seek treatment; therefore, the aim of this study was to compare the psychological state of patients with moderate to severe malocclusion who seek orthodontic treatment with patients who suffer from similar malocclusion but do not seek treatment. Materials and Methods Minnesota multiphasic personality inventory-2 questionnaire which assesses psychological states of people were given to 100 subject with moderate to severe malocclusion who were undergoing orthodontic treatment and 100 subjects with similar malocclusion who did not request orthodontic treatment. All subjects had similar demographic variables. Clinical scales measured by the test included: Hypochondriasis, depression, hysteria, psychopathic deviate, paranoia, psychasthenia, schizophrenia, and hypomania. The questionnaire consisted of 71 questions, and the subjects had to mark “True” or “False” in response. The scores were transformed into T-scores by a trained psychologist. The results were evaluated by independent t-test. Results and Conclusion The results of the test showed that both treated and untreated subjects were in similar psychological state and were psychologically normal; therefore, it is likely that other factors affect patients’ willingness for seeking orthodontic treatment rather than their psychological state.

Evaluation of the stability of open bite treatment using a removable appliance with palatal crib combined with high-pull chincup

OBJECTIVE: The aim of this prospective study was to cephalometrically analyze the stability of dentoalveolar and skeletal changes produced by a removable appliance with palatal crib associated to high-pull chincup in individuals with anterior open bite treated for 12 months, and compare them to individuals with similar malocclusion and age, not submitted to orthodontic treatment, also followed for the same period. METHODS: Nineteen children with a mean age of 9.78 years old treated for 12 months with a removable appliance with palatal crib associated with chincup therapy were evaluated after 15 months (post-treatment period) and compared with a control group of 19 subjects with mean age of 9.10 years with the same malocclusion that was followed-up for the same period. Seventy-six lateral cephalograms were evaluated at T1 (after correction) and T2 (follow-up) and cephalometric variables were analyzed by statistical tests. RESULTS: The results did not show significant skeletal, soft tissue or maxillary dentoalveolar changes. Overall, treatment effects on the experimental group were maintained at T2 evaluation with an increase of 0.56 mm in overbite. Overjet and maxillary incisors/molars position (vertical and sagittal) remained essentially unchanged during the study period. Only mandibular incisors showed significant changes (labial inclination and protrusion) compared to control group. CONCLUSIONS: Thus, it can be concluded that the early open bite treatment with a removable appliance and palatal crib associated with high-pull chincup therapy provided stability of 95%.

The prevalence of TMJ osteoarthritis in asymptomatic patients with dentofacial deformities: a cone-beam CT study

Osteoarthritis of the temporomandibular joint (TMJ) can be described as non-inflammatory arthritic condition that results in degenerative changes of the joint structures. The aim of this study was to evaluate the skeletal morphology of the TMJ in patients with osteoarthritis with severe skeletal malocclusions (Class II and Class III) and patients with Class I occlusion as controls. Cone beam computed tomography images of 45 Class I, 28 Class II and 44 Class III joints of Caucasian patients were assessed for the presence of any degenerative changes in the condyle and fossa/eminence complex as described in the research diagnostic criteria for temporomandibular disorders (RDC/TMD). In all groups, the most commonly observed features were articular surface flattening and subcortical sclerosis. A combination of features that corresponds to a diagnosis of osteoarthritis was observed in 3% Class I, 43% Class II and 20% Class III patient joints. In conclusion, degenerative TMJ changes were more common in patients with skeletal jaw discrepancies, but wide inter-individual variations can be observed even in patients with clinically similar malocclusions.

Maxillary Protraction Effects on Anterior Crossbites

To test the hypothesis that there is no difference between the effects of maxillary protraction on anterior crossbites in repaired unilateral cleft lip and palate (UCLP) and noncleft prepubertal boys. Eighteen operated UCLP boys with anterior crossbite (aged 9.54 +/- 1.21 years) were the experimental subjects. Eighteen noncleft boys with similar malocclusion (aged 9.75 +/- 1.46 years) were selected as a control group. A Hyrax appliance and reverse headgear were applied. Lateral cephalometric radiographs were taken before and after the treatment. Computerized cephalometric analysis and statistics were carried out. There were no significant differences in anterior movement of point A between the two groups (P > .05). ANB increased by 3.82 degrees and A-Pg (FH) increased by 5.89 mm in the UCLP group. ANB increased by 2.68 degrees and A-Pg (FH) increased by 3.66 mm in the noncleft group. The change of sagittal skeletal intermaxillary relationships was significantly larger in the UCLP group than in the noncleft group (P < .05). The change of lower lip in the UCLP group was less than in the noncleft group (P < .05). : The hypothesis is rejected. The changes of sagittal skeletal intermaxillary relationship and mandibular clockwise rotation were larger in the operated UCLP patients than in the noncleft subjects. The amount of the lower lip retrusion was significantly less in the UCLP patients.

Anchorage value of surgical titanium screws in orthodontic tooth movement

The aim of this study was to evaluate the clinical stability and anchorage value of titanium screws in orthodontic tooth movement. Nine patients, who needed maximum anchorage for canine retraction, were selected. Records of 10 patients with similar malocclusions who had received conventional treatment were used as controls. In the maxilla and mandible 27 mini-screws, diameter 2 mm and length 9 or 11 mm, were used. At the end of the first stage of orthodontic treatment the first premolar teeth were extracted after taking a lateral cephalometric radiograph. After 1 week, a retraction force of 180 g was applied to the canines. The second cephalometric X-rays were taken and evaluated after the completion of canine retraction (mean duration of 23.2 weeks). Results were analysed using Fisher Exact, Wilcoxon signed ranks and paired t-tests. Displacement of the first molars and screws before and after treatment showed no significant changes in either the vertical or horizontal plane. The first molar movements in the study and control groups were only significant in the antero-posterior plane in both maxilla and mandible. Of the 9 screws in maxilla and 18 screws in mandible, 2 and 3 screws showed clinical failure, respectively. The failed screws were replaced by other screws that withstood the applied force until the end of treatment. In conclusion, titanium screws can be used reliably as a form of anchorage.

An investigation of 202 pairs of twins regarding fundamental factors in the aetiology of malocclusion

Investigations concerning the aetiology of malocclusion have, in recent years, taken up still greater space in the orthodontic literature. Much of this work has been devoted to the effect of different environmental factors and an endeavour has been made to analyse the effect of such factors as birth injuries, finger sucking and other habits, extractions of deciduous and permanent teeth, insufficient function of the jaws, nasal and throat disturbances and lack of vitamins. These investigations show clearly that none of these factors inevitably produce malocclusion. On the contrary, more exact determinations on larger quantities of material have shown rather slight connections between the occurrence of these factors and malocclusion. This seems to imply that other factors must be of importance, among which the genetic factors take first place. The significance of heredity can be studied mainly along three lines, namely by experiments on animals, by family investigations and by twin investigations. All these methods have been used in the study of malocclusion of the teeth. Crossing-experiments on animals can give us certain indications as to the fundamental principles concerning the inheritance of malocclusion but it is, of course, not possible to know if the results of such experiments are significant for man also regarding similar malocclusions. Family investigations based on fairly large numbers are very difficult to make as it is so difficult to obtain reliable information of the occlusion, even in only two generations, on account of the high frequency of extractions in our time. It is much easier to obtain a fairly large number of twins for investigation and this method has also been used by several authors in the study of the aetiology of malocclusion. As is well known, one can, through observation of twins, get a conception of the influence of genetic factors as compared with …

The early signs of malocclusion

Although it may appear, when examining the deciduous dentition, that similar malocclusions to those seen in the permanent dentition can be identified, it does not always follow that they will persist. Incipient crowding of the teeth is usually masked by spacing which should normally be present. Small discrepancies of occlusion can arise or be masked as a result of deviation of the mandible away from centric occlusion. Unilateral crossbites, anterior open bites and excessive overjets which are associated with a sucking habit, will usually prove transient and improve spontaneously. It is also possible that crossbites and buccal occlusion of individual premolars may develop as these teeth erupt; these are often caused by displacement due to crowding. If these factors are allowed for then a fairly accurate prediction of arch relationship can be made. Correlations of tooth size, arch size and spacing of teeth were not strong enough to be used individually for predicting the degree of crowding to be expected in the permanent dentition. However, observation of all these factors, especially if radiographs are available may be used to give a fairly accurate prognosis.

The effectiveness of laceback ligatures: A randomized controlled clinical trial

To evaluate the effects of laceback ligatures on the anteroposterior and vertical position of lower incisors and the mesial position of the lower first molars. Randomized controlled trial. Patients under treatment in the Department of Orthodontics, Royal Bournemouth Hospital, Dorset, during a 6 month period from November 1999 to March 2000. Sixty-two adolescents (mean 13.7 years, range 11.2-16.8 years) with similar malocclusions, requiring extraction of all first premolars, were randomly assigned to experimental (laceback: 30; 12 male, 18 female) and control (non-laceback: 32; 14 male, 18 female) groups. Treatment using upper and lower fixed appliances following extraction of four premolars. One group had lacebacks placed, whilst the control group had no lacebacks. The participants were examined clinically and radiographically, and lateral cephalograms with radio-opaque tooth markers and lower study casts records were taken when lower fixed appliances were placed (T1) and following sufficient leveling with a 0.018 inch stainless steel round wire (T2). Linear measurements were recorded following digitization of the lateral cephalograms and using a vernier caliper on the study casts. A Student t-test was used to examine differences between the two groups following assessment for normality. In both groups the lower incisors retroclined during T1-T2; (Mean+/-SD: Experimental -0.53+/-1.9 mm, Control -0.44+/-1.29 mm). There was no statistical significance between the two groups (p = 0.84). The lower incisors extruded in both groups; 0.47+/-0.98 mm in the experimental group and 0.44+/-0.87 mm in the control group. There was no statistical difference between the groups (p = 0.9). The lower first molars showed 0.83 mm greater mesial movement in the experimental group, which was statistically significant (p < 0.05). Labial segment crowding decreased in both groups (experimental -3+/-1.6 mm, control -2.67+/-2.28 mm), the difference between the groups being non-significant (p = 0.51). Arch length decreased in both groups (experimental -2.08+/-2.82 mm , control -2.9+/-3.06 mm), but the difference between them was not significant (p = 0.28) In first premolar extraction cases, the lower labial segment does not procline during the leveling stage with the pre-adjusted edgewise appliance and the use of laceback ligatures conveys no difference in the anteroposterior or vertical position of the lower labial segment. Furthermore, the use of laceback ligatures creates a statistically and clinically significant increase in the loss of posterior anchorage.

Three-dimensional assessment of morphologic changes of the maxilla: A comparison of 2 kinds of palatal expanders

Previous studies of the morphologic changes of the maxilla after palatal expansion have used 2-dimensional methodologies. In the present study, we used a 3-dimensional surface laser scanning technique and computerized cast analysis, in addition to analysis of anteroposterior cephalograms, to assess the morphologic changes of the palate by 2 kinds of expanders: tissue borne (Haas; n = 9) and tooth borne (Hyrax; n = 10). Cast analysis demonstrated that, although all patients started treatment with similar malocclusion, treatment outcomes were different depending on the appliance used. Both appliances generated maxillary expansion (ie, improved mean surface area, mean intermolar linear distance, and mean perimeter) ( P < .05). However, the appliances performed differently to achieve the final expansion. Haas appliances demonstrated a greater orthopedic movement (ie, improvement of the mean interpalatal distance) ( P < .05), and Hyrax appliances demonstrated dentoalveolar expansion by increasing the mean palatal angulation of the alveolus ( P < .05). Anteroposterior cephalometric analysis showed that both appliances increased mean maxillary width and mean intermolar distance significantly ( P < .05). On the other hand, differences in nasal cavity width and upper incisal apex distance were not statistically significant ( P > .05). This new 3-dimensional methodology proved useful for comparing treatment outcomes by evaluating the morphologic changes induced by palatal expansion and generated a better visualization of these outcomes.

A 3-dimensional analysis of molar movement during headgear treatment.

Superimposition of serial cephalograms provides a limited description of tooth movement that could be complemented by data obtained from serial dental casts. The aim of this study was to develop a mathematical method for superimposing 3-dimensional data obtained from selected landmarks on longitudinally collected dental casts to describe maxillary first molar movement during headgear treatment. The material consisted of dental casts taken bimonthly from 36 children whose Class II Division 1 malocclusion was treated with straight-pull headgear during a 24-month period. Control data were collected from initial and final models of 38 subjects with a similar malocclusion who were not treated during a 24-month observation period. Spatial data from each subject's initial model were oriented similarly in an anatomically derived coordinate system, and a best-fit superimposition of palatal rugae landmarks from subsequent models allowed the measurement of molar movement. On average, headgear treatment resulted in distal movement of the molars, and the fitted net difference between treated and control subjects was 3.00 mm (SE, 0.37 mm; P < .001). Also, the headgear caused significantly more molar extrusion (0.56 mm; SE, 0.20 mm; P < .006) and buccal expansion (0.58 mm; SE, 0.17 mm; P < .001) on average than in the control group. Poor reliability of the method for measuring molar rotations indicated that they could not be determined accurately. Longitudinal description of molar movement for each subject revealed great individual variability in the amount and pattern of tooth movement. Several reasons could account for the wide range of individual variation and warrant exploration.

Skeletal and dental changes with nonextraction Begg mechanotherapy in patients with Class II Division 1 malocclusion

This prospective cephalometric study was undertaken to assess the mode and magnitude of Class II correction with nonextraction Begg mechanotherapy in growing children. The sample comprised subjects with similar malocclusion and age range (9-12 years) who were specifically selected for nonextraction Begg mechanotherapy. Cephalograms were analyzed to assess the skeletal, dental, and soft tissue changes that occurred after correction of the molar relationship, the overjet, and the overbite during the 9-month treatment period. The results revealed a significant improvement in the anteroposterior jaw relationship, suggested by the significant reduction in the ANB angle (1.62°) and in Wits AO-BO (1.42 mm). The mandibular length increase of 0.56 mm suggests that the Class II elastics used in nonextraction Begg mechanotherapy had a minimal stimulatory effect on mandibular growth. There was a significant increase in the anterior and posterior facial heights and the ramal height. Almost all of the dental changes were significant. The most striking feature were a significant retraction and extrusion of the maxillary incisors and proclination and intrusion of the lower incisors accompanied by extrusion of the mandibular molars. The maxillary incisors extruded by 1.64 mm under the influence of the undesirable downward component of the Class II elastic forces. The major contribution to overjet and molar correction was predominantly dentoalveolar. (Am J Orthod Dentofacial Orthop 2000;118:641-8)