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PubMed1995

Mandibular skeletal changes induced by early functional treatment of Class III malocclusion: a superimposition study.

A superimposition study on mandibular stable structures was performed to evaluate changes in mandibular rotation and in the direction of condylar growth induced by early treatment of Class III malocclusion by a functional appliance (removable mandibular retractor). A sample of 18 children with treated Class III malocclusions, mean age at the first observation (immediately before the beginning of treatment) 5.47 +/- 1.14 years, mean age at the second observation 8 +/- 1.29 years, mean observation period 2.5 +/- 0.9 years, was compared with a control group of 18 children with untreated Class III malocclusions, mean age at the first observation 5.72 +/- 1.11 years, mean age at the second observation 7.86 +/- 1.44 years, mean observation period 2.27 +/- 0.92 years. No statistically significant difference between the two groups was recorded for positional (total) rotation of the mandible. A significant upward-forward direction of condylar growth was assessed in the treated group (p < 0.001). This therapeutically induced change in growth direction of the mandibular condyle was considered a skeletal sign of anterior morphogenetic rotation of the mandible, i.e., a mechanism compensating for excessive mandibular growth.

Adaptation, Physiological↗
PubMed1995

Long-term stability of Angle Class II, division 1 malocclusions with successful occlusal results at end of active treatment.

The purpose of this study was to examine long-term stability of Angle Class II, Division 1 malocclusions with successful occlusal results at the end of active appliance therapy, search for predictors of relapse, and look for characteristics associated with successful treatment. Records taken before and after treatment and a mean of 14.0 years postretention of adolescent patients treated for a significant Angle Class II, Division 1 malocclusion both with and without tooth extraction were evaluated. The sample was limited to successfully treated cases as judged by subjective evaluation of intercuspation and incisor occlusion of posttreatment study models and included 78 patients. Cephalometric characteristics or postretention occlusion was not considered in sample selection. The mode response was no change postretention for molar, premolar, and canine relationships and relapse of 0.5 mm for overjet and overbite. Maximum relapse was 3.5 mm for molar, premolar, and canine relationship, 3 mm for overjet, and 4.5 mm for overbite. Stepwise backward multiple regression analyses revealed no associations between either pretreatment characteristics or skeletal and dental treatment changes and relapse of overjet. However, relapse of overjet was associated with relapse of molar, premolar, and canine relationships, postretention increase in overbite, postretention proclination of maxillary incisors, and postretention retroclination of mandibular incisors. Active treatment changes included redirection or inhibition of maxillary growth and retraction of maxillary incisors. Mandibular incremental growth was favorable both during and after treatment. It was concluded that successful correction of Angle Class II, Division 1 malocclusions through differential growth adaptation and tooth movement appears to be very stable.

Activator Appliances↗
PubMed1996

Craniofacial changes induced by early functional treatment of Class III malocclusion.

To evaluate the effects of a functional appliance (removable mandibular retractor) on the craniofacial skeleton in children with Class II malocclusions, a longitudinal cephalometric study was performed. A sample of 30 children with treated Class III malocclusions (18 boys, 12 girls, mean age at the first observation 5.64 +/- 1.01 years, mean age at the second observation 8.43 +/- 1.73 years) was compared to a sample of 30 children with untreated Class III malocclusions (13 boys, 17 girls, mean age at first observation 6.06 +/- 1.14 years, mean age at the second observation 8.45 +/- 1.79 years) used as controls. The treated group matched the control group as to sex, age at the first observation, age at the second observation, observation period, Class III occlusal signs, and also as to angular craniofacial dimensions at the first observation. A cephalometric analysis based on a stable basicranial reference system was applied. The main significant findings in the treated group were an anterior morphogenetic rotation of the mandible as a result of an upward-forward direction of condylar growth, a more vertical orientation of the ramus, and a reduced gonial angle; reduced mandibular protrusion and total length; increased maxillary protrusion; increased maxillary dentoalveolar protrusion and reduced mandibular dentoalveolar protrusion. No significant changes in the vertical craniofacial relationships and in cranial base angulation were observed. The role of an early correction of Class III occlusal relationship in the establishment of a more favorable craniofacial growth pattern was discussed.

Age Factors↗
PubMed1997

Shape-coordinate and tensor analysis of skeletal changes in children with treated Class III malocclusions.

The current study was undertaken to evaluate both maxillary and mandibular shape/size changes in children with Class III malocclusions, treated with a functional appliance (removable mandibular retractor). Nonconventional cephalometric methods (Bookstein's shape coordinate analysis, centroid size analysis, and tensor analysis) were applied to a maxillary triangle (T-FMN-A) and to a mandibular triangle (Co-Go-Pg). A group of 30 children with treated Class III malocclusions were compared with a matched group of 30 children with untreated Class III malocclusions. Treatment with the functional appliance produced a significantly increased growth of the maxilla, featuring a more downward and forward displacement of the region of point A and a significantly more upward and forward direction of condylar growth, leading to a "shrinkage" of total mandibular length. The biologic significance of some conventional cephalometric measurements used for the assessment of both maxillary and mandibular position and structure was tested.

Activator Appliances↗
PubMed1997

Predictive variables for the outcome of early functional treatment of Class III malocclusion.

The aim of this study was to select a model of cephalometric and occlusal predictive variables for the results of early treatment of Class III malocclusion, due to mandibular protrusion in the deciduous dentition. Lateral cephalograms and dental casts of 45 subjects (22 boys and 23 girls) with Class III malocclusion in the deciduous dentition were analyzed at the start of treatment (mean age 5.57 +/- 0.85 years). The patients were treated with a functional appliance (removable mandibular retractor). All subjects were reevaluated after a mean period of 9.54 +/- 2.28 years comprising active treatment plus retention. At this time, the sample was divided into two groups according to occlusal criteria: successful group (23 subjects) and unsuccessful group (22 subjects). Stepwise variable selection on the measurements at the time of first observation identified three predictive variables; the inclination of the condylar axis in relation to the stable basicranial line (CondAx-SBL), the inclination of the nasal line to the mandibular line (NL-ML), and the transverse width of the mandibular arch measured at the first deciduous molars. Discriminant analysis assigned a classificative power of 95.55% to the predictive model. On the basis of the equation generated by the multivariate statistical method, outcome of early treatment for each new case with Class III malocclusion in the deciduous dentition can be accordingly predicted. The important role of both vertical and transverse relationships in Class III prognosis was emphasized.

Age Factors↗
PubMed1998

Mandibular changes in persons with untreated and treated Class II division 1 malocclusion.

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

Adolescent↗
PubMed1998

Headgear versus function regulator in the early treatment of Class II, division 1 malocclusion: a randomized clinical trial.

A prospective randomized clinical trial was conducted to evaluate the early treatment of Class II, Division 1 malocclusion in prepubertal children. Facial and occlusal changes after treatment with either a headgear or a Fränkel function regulator are reported. Molar and canine relationships, overjet, intermolar and intercanine distances were measured from casts taken every 2 months, and mounted on a SAM II articulator. Cephalometric radiographs were taken annually. The results indicate that both the headgear and function regulator were effective in correcting the malocclusion. A common mode of action of these appliances is the possibility to generate differential growth between the jaws. The extent and nature of this effect, as well as other skeletal and occlusal responses differ. Treatment in late childhood was as effective as that in midchildhood. This finding suggests that timing of treatment in developing malocclusions may be optimal in the late mixed dentition, thus avoiding a retention phase before a later stage of orthodontic treatment with fixed appliances. However, a number of conditions may dictate an earlier intervention in the individual patient.

Adolescent↗
PubMed1999

Orthodontic correction of a class III malocclusion in an adolescent patient with a bonded RPE and protraction face mask.

A case report of a 14-year-old Hispanic male with a Class-III skeletal profile and dental malocclusion with a long mandibular body and ramus and retrusive maxilla. The patient was initially referred for a surgical evaluation for a LeFort I maxillary advancement, but he wanted to avoid surgery. The Class-III malocclusion was corrected with a bonded rapid palatal expander and a maxillary protraction mask followed by nonextraction orthodontic treatment. A Class-I molar and canine relationship was achieved, and the facial profile improved. This case report demonstrates the orthodontic correction of a Class-III malocclusion in an adolescent patient with a bonded rapid palatal expander and protraction face mask. This case was presented to American Board of Orthodontics as partial fulfillment of the requirements for the certification process conducted by the Board.

Adolescent↗
PubMed2006

Morphometric analysis of mandibular growth in skeletal Class III malocclusion.

BACKGROUND: The craniofacial growth patterns of untreated individuals with skeletal Class III malocclusion have rarely been systemically investigated. This study used morphometric techniques to investigate the growth characteristics of the mandible in individuals with skeletal Class III malocclusion. METHODS: Lateral cephalometric head films of 294 individuals with untreated skeletal Class III malocclusion (134 males, 160 females) were selected and divided into five triennial age groups (T1-T5) and by gender to identify the morphologic characteristics and sexual dimorphism in changes of mandibular growth. Procrustes, thin-plate spline, and finite element analyses were performed for localization of differences in shape and size changes. Maximum and minimum principal axes were drawn to express the directions of shape changes. RESULTS: From T1 (age 6-8 years) to T4 (age 15-17 years), the distribution of localized size and shape changes of the mandible was very similar between the two genders. From T1 to T2 (age 9-11 years), significant lengthening of the condylar region was noted (23.4-39.7%). From T2 to T3 (age 12-14 years), the greatest size and shape change occurred at the condylar head (27.4-34.9%). From T3 to T4, the greatest size and shape changes occurred in the symphyseal region (23.6-42.1%). From T4 to T5 (age>or=18 years), significant sexual dimorphism was found in the distribution and amount of localized size and shape changes. Females displayed little growth increments during T4. Despite differences in the remodeling process, the whole mandibular configurations of both genders exhibited similarly significant upward and forward deformation from T4 to T5. CONCLUSION: We conclude that thin-plate spline analysis and the finite element morphometric method are efficient for the localization and quantification of size and shape changes that occur during mandibular growth. Plots of maximum and minimum principal directions can provide useful information about the trends of growth changes.

Adolescent↗
PubMed1997

Facial growth of skeletal Class III malocclusion and the effects, limitations, and long-term dentofacial adaptations to chincap therapy.

This article outlines the authors' research findings on the craniofacial growth of untreated skeletal Class III malocclusion, as well as the short-term and long-term effects of chincap orthopedic force for controlling Class III mandibular growth. Skeletal Class III malocclusion is believed to be the result of excessive growth of the mandible with respect to the maxilla and/or cranial base. The results of the authors' longitudinal studies show similar maxillary and mandibular incremental growth change during prepubertal, pubertal, and postpubertal periods when compared with Class I subjects. Therefore, it seems reasonable to assume that the skeletal framework of the Class III malocclusion must have been established before the prepubertal growth period. As for treatment with chincap appliances, the study on short-term and long-term effects indicate that, on average, the skeletal profile is greatly improved during the initial stages of chincap therapy. However, such changes are rarely maintained during pubertal growth period. Treatment with chincap appliances seldom alters the inherited prognathic characteristics of skeletal Class III profiles after completion of growth.

Adaptation, Physiological↗
PubMed1997

Combined rapid maxillary expansion and protraction facemask in the treatment of Class III malocclusions in growing children: a prospective long-term study.

A prospective study of 28 growing children (mean age of 8 years 3 months) with Class III malocclusions was consecutively treated using rapid maxillary expansion and maxillary protraction. All patients were treated from a negative overjet to a positive overjet and from a Class III dental malocclusion to a Class I dental relationship. For each patient, a lateral cephalogram was taken before treatment (T1), immediately posttreatment (T2), and after an observation period (T3) averaging 2 years 5 months. Using analysis of variance, the cephalograms were analyzed to determine skeletal and dental changes resulting from treatment. Long-term changes (2 years 5 month observation period) were also evaluated. Results showed that immediately posttreatment, the maxilla moved anteriorly a mean of 1.54 mm and Sella-Nasion-A point increased 0.87 degree. The maxillary teeth moved anteriorly 2.73 mm and proclined 5.23 degrees, while the mandible rotated in a downward and backward direction. Long-term, the anterior position of the maxilla was maintained, but some of the Class III correction was lost because of mandibular growth. Comparison of this study's results to Riolo's longitudinal Class I data showed that, overall, rapid palatal expansion and maxillary protraction produced a small orthopedic effect with a moderate dentoalveolar effect which together contributed to the correction of the Class III malocclusion.

Adolescent↗
PubMed1998

Unlocking orthodontic malocclusions: an interplay between form and function.

It is possible to unlock dental malocclusions in a functional or mechanical manner, or in a combination of these two processes. Functional unlocking starts with an in-depth diagnosis of all aspects of a specific malocclusion including a recognition of those craniofacial dysfunctions that may be present. Craniofacial dysfunctions that may require treatment include those that involve the vegetative processes of breathing and swallowing and all aspects of cranial posture. This form of unlocking deals with the working environment of the oral cavity, that here, is also referred to as the oral functional matrix. Functional unlocking encompasses cognitive awareness training that involves patients in the treatment of their dysfunction. The early resolution of oral dysfunctions is not only an essential part of orthodontic treatment but it is also a vital component of the stability of the treatment results obtained. Mechanical unlocking, in contrast to functional unlocking, removes occlusal interferences that could interfere with the development and function of the entire stomatognathic system. Both functional and mechanical unlocking are often overlooked in orthodontic diagnosis and treatment planning. This article uses clinical examples, where possible, to illustrate how malocclusions may be unlocked to provide better and more stable treatment results.

Cephalometry↗
PubMed2003

Effects of the headgear-activator Teuscher appliance in the treatment of Class II Division 1 malocclusion: a geometric morphometric study.

OBJECTIVES: To test the hypothesis that there are no gender differences in the outcomes of patients with class II malocclusion treated with the headgear-activator Teuscher appliance (HATA). DESIGN: Retrospective, longitudinal SETTING AND SAMPLE POPULATION: Puerto Rico and Scotland, UK. Thirty-one patients requiring correction of class II division 1 malocclusions. EXPERIMENTAL VARIABLE: Male and female patients treated using HATA. OUTCOME MEASURES: Mean pre- and post-treatment parameters derived from cephalometry subjected to t-tests, and finite-element scaling analysis (FESA), which localizes and quantifies differences between mean pre- and post-treatment configurations. RESULTS: Post-treatment, cephalometry showed that for both males and females, angle SNA decreased, SNB increased, and lower facial heights increased significantly (p < 0.01). For the female post-treatment configuration, FESA revealed large size increases (approximately 20%) located in the inter-maxillary region, the ramus and mandibular body, and around the nasal and mental regions. Conversely, the lip region was diminished (approximately 20%). Similarly, male post-treatment showed size increases located in the inter-maxillary region that extended into the nasal region and the mandibular body (approximately 10-15%), and around the chin (15%). The lip region was diminished (approximately 5%). CONCLUSION: In the attainment of a normal occlusion, both male and female patients treated for class II malocclusions using HATA exhibit antero-posterior restraint of the maxilla, improvements in the mandible maintaining facial height, and lip changes commensurate with improvements in the soft tissue profile.

Activator Appliances↗
PubMed1978

A radiographic study of tongue posture at rest and during the phonation of /s/ in class III malocclusion.

In this investigation a group of individuals with Angle Class III malocclusions were studied radiographically to determine their tongue posture at rest and during phonation of /s/. Their speech and hearing was also evaluated. All of the subjects had normal hearing, while eleven of the twelve in the group showed some degree of sibilant distortion. At rest, these Class III subjects demonstrated a tongue posture that was lower than normal and more retruded. During the phonation of /s/ these individuals also demonstrated retrusion of the tongue in an apparent attempt to achieve a normal relationship of the tongue tip to the maxillary anterior teeth, an increased amount of mandibular depression, and a greater than normal distance between the tongue tip and the mandibular anterior teeth. Despite the compensatory movements exhibited by these individuals with Class III malocclusions, normal /s/ production was found in only one of the twelve subjects studied. This is in contrast to the successful compensations that result in normal /s/ production seen in a great number of individuals with a Class III, Division 1 malocclusion, as demonstrated by Subtelny, Mestre and Subtelny.

Adolescent↗
PubMed1982

Anterior malocclusion and soft tissue profile related to sound production and self-concept.

The objective of this study was to relate self concept and sound production to skeletal malocclusion and soft tissue facial profiles. The sample group consisted of forty-seven subjects divided into two groups. One group of eleven was selected on the basis of not having malocclusions from patients seeking general dental care. The other group of thirty-six subjects was selected on the basis of presenting a malocclusion and was chosen from patients seeking orthodontic care. Both groups were between the ages of eleven and fifteen. The findings indicate a high degree of correlation for the following: 1. Upper lip tip and the lower lip tip with skeletal convexity at Point A. 2. Convexity at Point A and abnormalities in self concept and speech production.

Adolescent↗
PubMed1995

Statistical analysis of differential lissajous EMG from normal occlusion and Class III malocclusion.

The method of differential lissajous electromyography (DL-EMG) was applied to investigate the relationship among the integrated EMG activity, timing, and coordination of the bilateral superficial anterior temporal and masseter muscle activities in normal occlusion and Class III malocclusion subjects. In both Class III malocclusion and normal occlusion subjects, the working side muscles showed a higher mean cumulative voltage (MCV) and mean maximum peak voltage (MMPV) compared with the balancing side. In addition, a higher MCV and MMPV of the working side masseter was observed in the normal occlusion group compared with that seen in the Class III group during both right and left side chewing (p < 0.01). Discriminant analysis applied to examine the distribution, the size and the shape of DL-EMG pattern further indicated a statistical difference between subject groups (p < 0.01). Finally, there was a significantly higher percentage of clockwise DL-EMG pattern-generation in the normal group compared with that seen for Class III subjects (p < 0.01). These data indicate that, compared with normal subjects, patients with a Class III malocclusion have a demonstrably abnormal masticatory muscle balance which is well characterized by the DL-EMG method.

Adolescent↗
PubMed1997

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.

Adolescent↗