Growth and treatment changes in patients treated with a headgear-activator appliance

Does mandibular advancement with clear aligners have the same skeletal and dentoalveolar effects as traditional functional appliances?

BACKGROUND

The study aimed to compare the dentoskeletal effects of Vanbeek Activator, Herbst, Twin-Block and Mandibular Advancement with clear aligners in children with skeletal Class II malocclusions.

METHODS

A sample with sixty-three patients (37 males, 26 females) was included and divided into untreated control group (C, n = 12), Vanbeek Activator group (V, n = 14), Herbst group (H, n = 11), Twin-Block group (TB, n = 12) and MA group (MA, n = 14). Cephalometric analysis and Johnston Pitchfork analysis were performed to quantify the skeletal and dentoalveolar components in molar relationship and overjet correction. Compare the differences of cephalometric data and Johnston-analysis data.

RESULTS

The treatment changes showed significant differences in SNB, FH-NP, NA-PA, Co-Go, Co-Pog, ANB, lower facial height ratio, U1-PP, U6-PP, L1-MP and U1-L1. All the appliances improved overjet relationships significantly (Vanbeek, Herbst, Twin-Block and MA were 2.77 mm, 5.53 mm, 4.73 mm and 3.66 mm respectively) with significant retraction of maxillary incisors. The lower incisor displacement of group V and MA was negative, while that of group H and TB was positive and there were significant differences. Molar relationships were also improved by 3.45 mm, 6.85 mm, 3.48 mm and 0.92 mm for Vanbeek, Herbst, Twin-Block and MA. Mandible displacement showed a trend of group H > TB > V > MA. The displacement of maxillary molars in group H was greater than that in group C, TB and MA, and that of mandibular ones was greater than that in group C, V and MA, significantly. Herbst, Twin-Block and MA have more significant dentoalveolar effect than Vanbeek, while Vanbeek has more skeletal effect than the others especially in restraining maxillary growth.

CONCLUSIONS

Four appliances are all effective in mandibular advancement, modification of class II molar relationship and deep overjet, with unavoidable increase in lower facial ratio. Vanbeek Activator has the most skeletal effects. Vanbeek and MA have a good control of mandibular incisors while more compensatory lower incisors proclination in Herbst and Twin-Block. Herbst has greater maxillary molar distalization. MA allows aligning and leveling meanwhile leading the mandible forward.

Cephalometric effects of Twin-block and van Beek Headgear-Activator in the correction of Class II malocclusion

INTRODUCTION

The Twin-block (TB) and the van Beek Headgear-Activator (vBHGA) are indicated for patients with Class II malocclusion with a retrognathic mandible. Although the former is commonly prescribed for horizontally growing patients, the latter is often recommended for those growing vertically. This study aimed to compare the skeletal, dentoalveolar, and soft-tissue short-term effects of TB and vBHGA, taking growth patterns into account.

METHODS

Immediate prefunctional (T1) and postfunctional appliance (T2) lateral cephalometric radiographs were retrospectively obtained for vBHGA (n = 46), TB (n = 45), and untreated control (n = 45) groups. The interaction of several variables at T1, T2, and T2 - T1, as well as the resultant treatment effect, were analyzed using the analysis of covariance regression models at the 5% significance level.

RESULTS

Except for a greater reduction in Wits measurement (3.0 mm; P <0.0001) in the TB group, no anteroposterior (AP) skeletal difference was observed between the 2 appliances (ANB, 0.530; P = 0.07) (Harvold, 0.13 mm; P = 0.81). Both improved the AP skeletal relationship (ANB and Harvold) compared with the control (P <0.05). Although this mostly occurred because of the forward positioning of the mandible with the TB (SNB, 0.960; P = 0.01), the maxillary restriction was the main mechanism with the vBHGA (SNA, 1.590; P <0.01). Dentoalveolar compensations were more pronounced with the TB (IMPA, 1.92; P = 0.02), leading to greater overbite and overjet correction. Only the inclination of the maxillary incisors showed interaction with the growth pattern, with the TB horizontal growers experiencing more retroclination (U1-NA°. 3.620; P = 0.0067).

CONCLUSIONS

Both appliances produced similar modest AP skeletal changes that, together with dentoalveolar compensations, were able to correct the Class II malocclusion regardless of growth pattern.

Camouflage treatment guided by facial improvement in hyperdivergent skeletal class II malocclusion

Background

To detect parameters associated with the craniomaxillofacial system that could be altered during hyperdivergent skeletal class II malocclusion camouflage treatment for better profile improvement.

Methods

Forty-two subjects with hyperdivergent skeletal class II malocclusion who had finished their orthodontic treatments and achieved good soft tissue responses were included in this study. Cephalometric analyses of these patients were taken before (T1) and after (T2) treatment. Measurements were made at each treatment stage and analyzed within and between groups.

Results

No obvious decrease in the cant of occlusal plane (OP) (the line of point L1 and point L7) and mandibular plane (MP) was observed. However, an obvious decrease in the cant of the posterior occlusal plane (POP) and the angle of plane NA and plane NB (ANB) and a significant increase in the distance from the condylar center (Dc) to OP (DPO) were observed in the subjects (P<0.05).

Conclusions

Decreased POP canting and increased DPO values play a vital role in profile improvement. Sagittal discrepancies might be considerably alleviated by a decreasing ANB angle [especially the sella nasion A point (SNA) angle]. Therefore, to attain a successful camouflage treatment of hyperdivergent skeletal class II malocclusion, treatment should be targeted towards finding an alternative to control POP canting, including reducing crowding in the posterior arch, as well as modifying and intruding molars to an upright and lower position.

Differential skeletal and dental effects after orthodontic treatment with bite jumping appliance or activator: a retrospective cephalometric study

OBJECTIVES

The aim of this retrospective cephalometric study was to compare treatment outcomes with "bite jumping appliance" (BJA) or Andresen-Häupl type activator. It especially focused on skeletal and dental structures in patients with class II malocclusion. The study hypothesis was that differences in treatment-related changes would occur between patients treated with BJA or activator.

MATERIAL AND METHODS

Pre- and posttreatment lateral cephalograms of 73 patients with a class II malocclusion were analyzed. Thirty-seven patients (22 females, 15 males) received treatment with a BJA (pretreatment age 11.1 ± 1.07 years) and 36 patients (20 females, 16 males) with an activator (pretreatment age 11.3 ± 1.12 years). Treatment time was 14.0 ± 1.8 months with BJA and 12.0 ± 2.0 months with activator. Paired t tests were used for intragroup and t tests for independent samples for intergroup comparisons. Results were considered statistically significant at P < 0.05.

RESULTS

The comparison of sagittal and vertical skeletal changes after BJA and activator treatment did not reveal significant differences. Significant changes occurred for lower incisor inclination (P = 0.0367) and overjet (P = 0.0125) only. The reduction of overjet and proclination of lower incisors were more pronounced in BJA patients.

CONCLUSIONS

Both "bite jumping appliance" (BJA) and Andresen-Häupl type activator were able to improve the occlusion of patients with a class II malocclusion. Dental effects were more pronounced for the BJA.

CLINICAL RELEVANCE

Marked lower incisor proclination contributed significantly to overjet correction in BJA patients. This ought to be respected when choosing a removable functional appliance for patients whose lower incisors are already proclined prior to treatment.

Histological Alterations from Condyle Repositioning with Functional Appliances in Rats

OBJECTIVE

This study was designed to assess the morphological and histological alterations of the condyle of rats undergoing forward mandibular repositioning via functional appliance.

MATERIALS AND METHODS

Functional appliances were mounted onto the upper jaws of rats. Morphological analysis was conducted on micro-CT images of sacrificed animals. Histological changes in condyle were examined by immunohistochemistry using proliferating cell nuclear antigen (PCNA), matrix metalloproteases (MMPs), vascular endothelial growth factor (VEGF), tissue inhibitors of matrix metalloproteinases (TIMP-1), interleukin 1b (IL-1β), Aggrecan and Type II collagen. Osteoclast activity was identified by tartrate-resistant acid phosphatase (TRAP) staining.

RESULTS

Morphological analysis confirmed the forward positioning of the condyles of rats by the appliance, but the position gradually returned to normal on days 14 after treatment. An increase in PCNA positive cells was observed in the posterior region of the condyles on days 7, whereas PCNA positive cells decreased in the anterior region. Aggrecan and Type II collagen localization increased in the posterior region throughout the entire period, but decreased in the anterior region on days 14. In both regions, IL-1β and VEGF localization was significantly increased for 14 days while MMPs localization was evident throughout the entire period. The TRAP positive cells were significantly elevated on days 3 and 7.

CONCLUSIONS

These results suggest that the functional appliance therapy induces significant morphological and histological changes in the anterior and posterior regions of the condyle and subsequently causes adaptive cellular functions such as chondrocyte differentiation and cartilage matrix formation.

Perception, knowledge and attitudes of Brazilian orthodontists on the treatment of Class II malocclusions

The present study aimed to assess the perception and knowledge of Brazilian orthodontists on the ideal moment to treat Class II malocclusions. Questionnaires with open, semi-open and close questions were sent by e-mail to 1653 Brazilian orthodontists. These orthodontists were registered in the Brazilian Association of Orthodontics and Dentofacial Orthopedics (ABOR). One-hundred and three (9.86%) Orthodontists replied to the questionnaires. Most of them were males (60.5%) with specialization as the highest level of professional qualification (59.9%). Most of the orthodontists (51%) reported preference for treating Class II malocclusions in late mixed dentition, followed by the early mixed dentition (29%). The age range between 10 and 12 years old figured as the most prevalent in patients searching for treatment (42.7%). Most of the patients searching for treatment were females (69.7%). Preferences for functional orthopedic appliances were reported by 35% of the orthodontists. Brazilian orthodontists revealed a trend for treating patients with Class II malocclusions in the late mixed dentition. Female patients aged from 10 to 12 years old represented the majority of patients that search for orthodontic treatment. Functional orthopedic appliances were preferred by Brazilian orthodontists for treating Class II malocclusions.

Class III Molar Finish as a Different Treatment Approach to Correct an Adolescent Class II Patient Using Headgear, Forsus, and Lower Arch Extraction

Various treatment strategies are adopted to correct a Class II malocclusion depending on the age, the amount of remaining growth and severity of malocclusion. Single arch extraction of the lowers is rarely done in a Class II malocclusion. The following case report describes an alternate treatment approach of an adolescent Class II patient treated with a combination of headgear, fixed functional appliance (forsus), and single arch extraction only in the lower arch. The case was finished in a Class III molar and a Class I canine relationship. The results were stable in 3 years follow-up.

Change of mandibular position during two-phase orthodontic treatment of skeletal class II in the Chinese population

The aim of this study was to evaluate the change in mandibular position during a two-phase orthodontic treatment of skeletal Class II malocclusion. Thirty consecutively treated Chinese male adolescents who had undergone two-phase treatment with Herbst appliance and fixed appliance and fulfilled the specific selection criteria were sampled. Cephalograms taken at T0 (before treatment), T1 (at the end of functional appliance treatment), and T2 (at the end of fixed appliance treatment) were analyzed. The change in sagittal positioning of the mandible was 6.8±3.44 mm in phase I (T0-T1), 0.4±2.79 mm in phase II (T1-T2), and 7.2±4.61 mm in total. The mandible came forward in 100% of the patients at T1. In phase II, it came forward in one-third (positive group) remained unchanged in one-third (stable group) and went backward in one-third (negative group) of the patients. At T2, it came forward twice as much in the positive group compared to the negative group. Mandibular length was significantly increased in 100% of the patients in both phases. In conclusion, during the treatment with functional appliance, the mandibular prognathism increases in all patients, whereas during the treatment with fixed appliance there is no significant change in mandibular prognathism.

Dentoskeletal changes induced by the Jasper jumper and the activator-headgear combination appliances followed by fixed orthodontic treatment

INTRODUCTION

The aim of this study was to compare the dentoskeletal changes of patients with Class II Division 1 malocclusion treated with either the Jasper jumper appliance or the activator-headgear combination, both associated with fixed appliances.

METHODS

The sample comprised 72 subjects with Class II Division 1 malocclusion divided into 3 groups: group 1 included 25 subjects treated with fixed appliances and the force modules of the Jasper jumper at an initial mean age of 12.72 years, group 2 included 25 subjects treated with the activator-headgear combination followed by fixed appliances at an initial mean age of 11.07 years, and group 3 included 22 untreated subjects at an initial mean age of 12.67 years. Initial cephalometric characteristics and dentoskeletal changes were compared with analysis of variance.

RESULTS

Both experimental groups had similar dentoskeletal changes: restrictive effect on the maxilla, clockwise mandibular rotation and a slight increase in anterior face height, retrusion of the maxillary incisors, distalization of the maxillary molars, protrusion of the mandibular incisors, extrusion of the mandibular molars, and significant improvements of the maxillomandibular relationship, overjet, overbite, and the molar relationship.

CONCLUSIONS

The effects of the Jasper jumper and the activator-headgear combination followed by fixed orthodontic appliances were similar in Class II malocclusion treatment.

New therapeutics in promoting and modulating mandibular growth in cases with mandibular hypoplasia

Children with mandibular growth deficiency may develop airway obstruction. The standard treatment of severe airway obstruction involves invasive procedures such as tracheostomy. Mandibular distraction osteogenesis has been proposed in neonates with mandibular deficiency as a treatment option to avoid tracheostomy procedure later in life. Both tracheostomy and distraction osteogenesis procedures suffer from substantial shortcomings including scarring, unpredictability, and surgical complications. Forward jaw positioning appliances have been also used to enhance mandible growth. However, the effectiveness of these appliances is limited and lacks predictability. Current and future approaches to enhance mandibular growth, both experimental and clinical trials, and their effectiveness are presented and discussed.

Occlusal plane canting reduction accompanies mandibular counterclockwise rotation in camouflaging treatment of hyperdivergent skeletal Class II malocclusion

Objective

To investigate the occlusal configurations of the hyperdivergent skeletal Class II malocclusion and their alterations during the camouflaging treatment in an attempt to identify occlusal changes that might be related to mandibular counterclockwise rotation.

Materials and Methods

Cephalograms of 126 subjects with hyperdivergent skeletal Class II malocclusion and 126 subjects with a clinically normal skeletal pattern were chosen. Several measurements were calculated and compared between the groups. To examine the effects of treatment, two groups were established according to mandibular rotation: counterclockwise rotation (CCR) and the opposite clockwise rotation (CR). After 40 subjects were excluded, the other 86 Class II subjects were assigned to CCR (n  =  22) and CR (n  =  64). Their pretreatment (T1), posttreatment (T2), and postretention (T3) cephalograms were obtained. Measurement changes (T3-T1) were analyzed in each group and compared between groups.

Results

Compared with the normal skeletal pattern, the cant of the occlusal plane (OP) of the study subjects was significantly steeper and the vertical heights of the incisors were significantly larger for the malocclusion. Compared with the changes in CR, there was a prominent reduction of the OP canting with remarkable intrusion of the maxillary incisor in CCR.

Conclusion

Increased OP canting with overerupted incisors is evident in the hyperdivergent skeletal Class II malocclusion. During the camouflaging treatment, reduction of OP canting could occur. It was accompanied by mandibular counterclockwise rotation and intrusion of the maxillary incisor.

[Success rate and efficiency of activator treatment]

In a retrospective multicentre study, the success rate and efficiency of activator treatment were analysed. All patients from two University clinics (Giessen, Germany and Berne, Switzerland) that fulfilled the selection criteria (Class II division 1 malocclusion, activator treatment, no aplasia, no extraction of permanent teeth, no syndromes, no previous orthodontic treatment except transverse maxillary expansion, full available records) were included in the study. The subject material amounted to 222 patients with a mean age of 10.6 years. Patient records, lateral head films, and dental casts were evaluated. Treatment was classified as successful if the molar relationship improved by at least half to three-fourths cusp width depending on whether or not the leeway space was used during treatment. Group comparisons were carried out using Wilcoxon two-sample and Kruskal-Wallis tests. For discrete data, chi-square analysis was used and Fisher's exact test when the sample size was small. Stepwise logistic regression was also employed. The success rate was 64 per cent in Giessen and 66 per cent in Berne. The only factor that significantly (P¡0:001) influenced treatment success was the level of co-operation. In approximately 27 per cent of the patients at both centres, the post-treatment occlusion was an ideal Class I. In an additional 38 per cent of the patients, marked improvements in occlusal relationships were found. In subjects with Class II division 1 malocclusions, in which orthodontic treatment is performed by means of activators, a marked improvement of the Class II dental arch relationships can be expected in approximately 65% of subjects. Activator treatment is more efficient in the late than in the early mixed dentition.

Variations in cyclic mandibular movements during treatment of Class II malocclusions with removable functional appliances

The aim of the study was to establish whether juveniles with a Class II malocclusion change the neuromuscular control of mandibular movements during the course of orthodontic treatment with removable functional appliances (RFAs). Neuromuscular control can be indirectly evaluated by recording cyclic planar mandibular movements which were freely carried out by the patients (28 girls, 14 boys, aged 11.1 ± 1.1 years at the start of treatment) and measured with an ultrasonic device before, during, and after Class II functional appliance therapy, with either an activator or a bite jumping plate. The cyclic movements represented simultaneous rotations of the mandible around a maxillary and mandibular fixed axis (MFHA) and could be characterized by μ(α)-diagrams (μ = swing angle of MFHA, α = mouth opening angle) and path length (L) of the MFHA. The μ(α)-diagrams clearly divided into four parts: movement representing protrusion, mouth opening, and two parts of backward closing as known from Posselt diagrams. Parameters from the Posselt and μ(α)-diagrams were checked by one-factor analysis of variance on a 5 per cent significance level for group dependency. For one-third of the patients investigated, no significant changes were seen in any parameter pre- or post-therapy. However, patients showing an initially large mouth opening capacity or a very short condylar path changed their neuromuscular control to that of Class I subjects. Analysis of μ(α)-diagrams provides the possibility of assessing changes in the neuromuscular control of the mandible during Class II treatment.

A retrospective cephalometric evaluation of dental changes with activator and activator headgear combination in the treatment of skeletal class II malocclusion

AIM

The aims of this study were to evaluate the dental changes brought about by activator and activator headgear combination (ACHG) and to determine whether we can achieve control over the lower incisor proclination which is a side effect of using functional appliances; or not, while treating cases of skeletal class II malocclusions.

METHODS

Lateral cephalograms of 45 skeletal class II division 1 patients were selected for the study. Fifteen of them were successfully treated with an Andresen activator and the other 15 with an activator headgear combination. Fifteen class II subjects who had declined treatment served as the control group. Cephalometric landmarks were marked by one author to avoid interobserver variability.

RESULTS

The results revealed that both the activator and the activator headgear combination significantly (p < 0.001) affected dental variables measured. The mandibular incisor proclination was effectively controlled in the activator headgear combination group.

CONCLUSION

An activator headgear combination would offer itself as a better option compared with activator alone in the treatment of skeletal class II malocclusions especially in cases with proclined mandibular incisors.

CLINICAL SIGNIFICANCE

When one of the treatment goals is to achieve a greater control over mandibular incisor proclination in the treatment of Skeletal Class II malocclusions, employing a combination of activator and headgear may substantially improve clinical outcomes.

The biological mechanisms of PCNA and BMP in TMJ adaptive remodeling

OBJECTIVES

To histologically and immunohistochemically assess the pattern of expression of bone morphogenic proteins 2 and 4 (BMP2/4) and proliferating cell nuclear antigen (PCNA) in response to bite jumping appliances in the condylar cartilage and the glenoid fossa.

MATERIALS AND METHODS

Fifty-five 4-week-old female Sprague-Dawley rats were randomly divided into four experimental and four control groups. Bite-jumping appliances were fitted to the experimental animals. The rats were sacrificed at 3, 14, 21, and 30 days, and the temporomandibular structures were analyzed histologically and immunohistochemically.

RESULTS

The expression of BMP2/4 in response to bite-jumping appliances was statistically significant in the condylar cartilage and the glenoid fossa. Cell proliferation was not significant.

CONCLUSION

BMP2/4 plays an important role in bone formation in response to mandibular advancement by accelerating and enhancing the differentiation of mesenchymal cells into bone-forming cells.

Long-term stability of dentoalveolar and skeletal changes after activator-headgear treatment

The aim of this study was to analyze the long-term stability of combined activator-headgear treatment on skeletal and dental structures in Class II patients. The material comprised 26 subjects, 10 girls and 16 boys. All had a molar Class II relationship, overjet > or =6 mm, and overbite > or =5 mm. They were treated in one practice with combined activator and headgear appliances. Lateral cephalometric radiographs and dental study casts were taken before treatment (T0, mean age 11.9 years), at the end of activator-headgear treatment (T1, mean age 15.9 years), and 12-15 years out of retention (T2, mean age 28.6 years). Nineteen cephalometric and nine dental cast variables were evaluated using a paired sample t-test between T0-T1, T1-T2, and T0-T2. At T1, the majority of the cephalometric measurements showed statistically significant changes. ANB was significantly reduced by 2.3 degrees due to a significant increase in SNB, but only small changes were observed in SNA. The interincisal angle increased as a result of significant retroclination of both maxillary and mandibular incisors. All patients achieved a Class I molar relationship and a significant reduction in overjet and overbite. At T2, the results showed only slight relapse from T1. However, the relapse did not compromise the significant improvement in almost all the cephalometric and dental variables. Combined activator-headgear treatment improved the skeletal and dental conditions and the results remained stable in the long term.

Condylar growth and mandibular positioning with stepwise vs maximum advancement

INTRODUCTION

The aim of this study was to compare the effects of several Class II malocclusion treatments on condylar growth and positioning of the mandible.

METHODS

The material comprised series of lateral cephalograms obtained at the start, after about 6 months, and after about 12 months of treatment from 3 groups of consecutively treated patients who used a headgear-activator with stepwise mandibular advancement (HGA-S), a headgear-activator with maximum jumping of the mandible (HGA-M), and a headgear-Herbst appliance with stepwise advancement (HGH-S), respectively. Six-month growth data from matched controls were used to calculate the net treatment effects.

RESULTS

Mandibular prognathism was enhanced after stepwise advancement but not after maximum jumping, and only during the initial phase of therapy; the effect was significantly greater for the fixed functional appliance than for the removable functional appliance. Lower-facial height was increased by the HGA-S, unchanged by the HGA-M, and restrained by the HGH-S. The low construction bite of the HGH-S meant that the extent of bone apposition on the posterior and superior parts of the condyle was similar, whereas the high construction bite of the HGA-S and the HGA-M meant that the effect on the superior part was greater, but only significantly so after stepwise advancement.

CONCLUSIONS

The mode of jumping, the vertical opening, and whether the functional appliance is fixed or removable affect the amount and pattern of condylar growth, and the position of the mandible.

Does the degree of advancement during functional appliance therapy matter?

The aim of this study was to assess the effect of varied degrees of mandibular advancement on condylar growth. Three hundred and thirty five 35-day-old female Sprague-Dawley rats were randomly divided into 10 experimental groups (n = 10) and five control groups (n = 5) for analysis of new bone formation and 10 experimental groups (n = 14) and five control groups (n = 14) for molecular analysis. The experimental animals were fitted with bite-jumping appliance to advance the mandible 2 and 4 mm. The rats were sacrificed on days 3, 7, 14, 21, and 30. A computer-assisted image analysing system was used to assess the quantity of new condylar bone formation. Molecular analysis utilizing real-time reverse transcription-polymerase chain reaction was used to assess the different levels of mRNA expression of different growth markers in the condyle. One-way analysis of variance (ANOVA), with a Bonferroni multiple comparison test, showed significantly more newly formed bone in the 4 mm group compared with the 2 mm and control groups on days 21 and 30 (P < 0.05). Most of the examined growth markers demonstrated a significant increase during the 4 mm advancement (P < 0.05). Indian hedgehog (Ihh) mRNA showed a 7- and 5-fold change, parathyroid hormone-related peptide (PTHrP) a 5.2- and 3-fold change and type II collagen a 9.6- and 3.7-fold change in the 4 and 2 mm advancement groups, respectively. Varied degrees of mandibular advancement result in different quantities of new bone formation and levels of expression of growth members: Ihh, PTHrP, and type II collagen.

Stepwise advancement versus maximum jumping with headgear activator

The aim of this study was to compare the effects of stepwise mandibular advancement versus maximum jumping and extended treatment versus early retention. The material was obtained prospectively and consisted of lateral cephalograms taken at the start (T0), after initial (T1), and at the end (T2) of treatment, from two groups of consecutively treated skeletal Class II patients who had undergone therapy with headgear activators. The first headgear activator group, HGA-S (n=24; mean age 11.9 +/- 1.2 years), was treated for 13 months and had 4-mm mandibular advancement every 3 months. The second headgear activator group, HGA-M (n=31; mean age 11.2 +/- 1.5 years), had maximum jumping, 6-8 mm interincisal opening, for a total of 15.4 months, and with reduced wear for the last 6.9 months. The dropout over 12 months was 41 and 46 per cent, respectively. Pre-treatment growth changes were obtained as a reference. An independent t-test was used to determine differences in baseline dentofacial morphology between the groups, a paired t-test for intra-group comparisons, and an independent t-test to evaluate differences between the groups. The results, in both groups, showed enhanced mandibular prognathism during the initial phase (T0-T1), followed by normal growth (T1-T2), and lower face height enhancement throughout treatment (T0-T2). For both groups, the mandibular plane and occlusal angle increased, possibly enhanced by 'extrusion' of the lower molars. For both groups, maxillary forward growth was restrained only during the initial phase, but the effect remained significant at T2 for the HGA-S group. In the HGA-M group, the lower incisors were protruded, while in the HGA-S group, they were unaffected. The findings indicate that both modes of mandibular jumping resulted in skeletal and dental effects. The length of active treatment seemed to be decisive in maintaining the treatment effects; stepwise advancement had less dental effects.

Treatment effects of the bionator and high-pull facebow combination followed by fixed appliances in patients with increased vertical dimensions

INTRODUCTION

The purpose of this study was to evaluate the effectiveness of a first phase of bionator and high-pull facebow treatment followed by a second phase of fixed appliance therapy in growing subjects with increased vertical dimensions.

METHODS

The records of 24 subjects with high-angle skeletal relationships (mean MPA value approximately 30 degrees) treated consecutively with this protocol were examined. Cephalometric measurements were compared with those obtained from 23 sets of records of an untreated group matched according to age, gender, vertical skeletal relationships, and time intervals between records. The matched group of patients was from the University of Michigan Elementary and Secondary School Growth Study. Lateral cephalograms were analyzed prior to the start of treatment (T1, mean age 9.1 years), at the start of phase 2 treatment (T2, mean age 11.9 years), and after phase 2 treatment (T3, mean age 14.7 years). The total treatment duration (phase 1, retention, and phase 2) for the treated group was 5.5 years, whereas the control group total time interval averaged 5.6 years.

RESULTS

As to sagittal relationships, no significant differences were found between treated subjects and controls at the end of the 2-phase treatment for all measurements. Counterintuitively, the bionator and high-pull headgear combination worsened the hyperdivergent facial pattern at a clinically significant level, as shown by analysis of final facial forms. The treated group exhibited a significantly larger MPA value than controls (2.5 degrees) as well as a larger inclination of the Frankfort horizontal to the occlusal plane (2.8 degrees ).

CONCLUSIONS

Based on the analysis of this sample, the examined therapeutic protocol does not appear to be a recommendable option for treatment of subjects with increased vertical dimensions.

Dentoskeletal Effects and “Effective” Temporomandibular Joint, Maxilla and Chin Changes in Good and Bad Responders to van Beek Activator Treatment

Objective: To assess possible differences in dentoskeletal effects and “effective” temporomandibular joint, maxilla, and chin changes between good and bad responders to van Beek activator treatment.

Materials and Methods: The subject material consisted of 20 consecutive normodivergent male Class II division 1 patients treated with a van Beek activator. Because of insufficient cooperation, four patients were excluded. Lateral head films were taken 6 months before treatment, at start of treatment, and after 12 months of treatment. The patients were placed into a good responder group (successful, n = 8) and a bad responder group (unsuccessful, n = 8). An overjet reduction ≥4 mm was considered successful.

Results: During the van Beek treatment period, the good responders showed a significantly larger improvement in overjet and molar relationship than did the bad responders. The good responders exhibited a significant posterior development of condylion, less anterior mandibular autorotation, retrusion of upper incisors, protrusion of lower incisors, distalization of maxillary molars, and a mesial movement of mandibular molars. No significant dental movements were seen in the bad responders.

Conclusions: Although van Beek activator treatment affected the direction of condylar growth, as well as the direction of maxilla and chin changes, it can be concluded that skeletal changes did not contribute to the Class II correction. Instead, overjet reduction during van Beek activator treatment was found to be due to a favorable dental reaction.

Correction of extreme overjet in 2 phases

This case report describes the treatment of a 12-year-old Chinese boy with a Class II skeletal profile, an extreme overjet, and a retrusive mandible. The patient was teased at school because of his appearance, and he was experiencing negative psychosocial impacts, including shyness and falling grades. Orthodontic treatment had a positive psychosocial impact on his life over a period of 10 years. The advantages of using functional appliances are highlighted in this report.

The Dynamax system: a new orthopaedic appliance and case report

The Dynamax appliance is a treatment modality for the correction of the Skeletal II malocclusion characterized by a mandibular retrusion. Progressive mandibular advancement, maxillary expansion, control of maxillary growth, incisor torque and control of vertical facial development are incorporated into a two-part appliance. The design facilitates laboratory construction, clinical handling and patient acceptability. A prefabricated spring module forms the basis of the appliance, allowing both maxillary expansion and mandibular advancement. An easily adjustable progressive forward position of the lower jaw makes a construction bite unnecessary. The spring module provides most of the structure of the appliance so that minimal acrylic is required and the appliance is fully contained within the freeway space. Contact between the upper and lower parts of the appliance occurs posteriorly in the lingual sulcus. Here the depth permits an extended vertical contact, to maintain a protrusive mandibular position throughout the range of mandibular opening, including during sleep. The lower portion of the appliance may be fixed or removable and multibracket treatment can be carried out in one or both arches at the same time as the orthopaedics.

Cephalometric evaluation of condylar and mandibular growth modification: a review

OBJECTIVE

Based on a wealth of orthodontic archives, this work aims to review the cephalometric analysis systems that can identify the changes in condylar and mandibular position as well as growth direction in response to bite jumping therapy.

DESIGN

Numerous cephalometric approaches were screened to testify their feasibility and reliability in accurately depicting the growth modification of the condyle and the mandible. The critical assessment of the working mechanisms of these cephalometric methods was elaborated to help build up the rationale and justification for their clinical use.

RESULTS

1) The changes in condylar and mandibular size, position and growth direction can be identified by using lateral cephalograms with closed-mouth or open-mouth posture. 2) With superimposition methods where the anatomical structures for superimposition registration must be stable and reproducible, the growth modification of the condyle and the mandible between two time-points is qualitatively demonstrated in a diagram if reference lines are not constructed. The growth modification can be quantitatively identified if the reference lines are created. 3) With non-superimposition methods, the size and position of the condyle and the mandible are separately identified for each time-pint by relating them to the stable reference structures. The growth modification between two time-pints is evaluated by comparing the two separate measurements.

CONCLUSION

The application of a standardized and well designed cephalometric evaluation system may reduce the bias that attribute to the arbitrariness of the clinical effects of bite jumping functional appliances.

Effects of activator and activator headgear treatment: comparison with untreated Class II subjects

The aims of this study were to determine whether the activator and activator headgear encourage mandibular growth, and whether there is any superiority of one appliance over the other or if the resultant changes are due to normal growth. Forty-nine skeletal Class II division 1 patients were selected. Thirty-three (13 females, 20 males; mean age 12.52 +/- 1.42 years) were treated with an Andresen activator and the remaining 16 (7 females, 9 males; mean age 13.04 +/- 1.47 years) with an activator headgear combination. Twenty Class II subjects (9 females, 11 males; mean age 12.57 +/- 1.11 years) who had previously refused treatment served as a control group. Cephalometric landmarks were marked and digitized by one author to avoid inter-observer variability. Nine angular and 12 linear measurements were established and measured using Vistadent AT software. A paired-sample t-test and an ANOVA test were used to statistically evaluate the findings. The results revealed that both the activator and the activator headgear combination significantly (P < 0.001) encouraged mandibular growth, but had little restraining effect on the maxilla. The mandibular incisors were more controlled in the activator headgear combination group. The resultant skeletal, dentoalveolar and soft tissue changes differed significantly from those due to growth.

Identification of temporal pattern of mandibular condylar growth: a molecular and biochemical experiment

OBJECTIVES

Based on the phenomenon that expression of type X collagen and capillary endothelium correlates with endochondral ossification, the prime aim of this study was to establish the temporal pattern of condylar growth in Sprague-Dawley rats by biochemically identifying the expression of these two factors.

DESIGN

Sprague-Dawley rats were divided into five groups representing five different stages during somatic pubertal growth. In situ hybridization and immunoperoxidase were performed to examine expression of type X collagen in hypertrophic zone and capillary endothelium in erosive zone of condylar cartilage. Computer-assisted imaging analyses were conducted to allow for a quantitative assessment of the expression of these two factors, from which the temporal pattern of condylar growth was inferred.

RESULTS

(1) Synthesis of type X collagen and emergence of capillary endothelium were critical factors during the transition of condylar cartilage from chondrogenesis into osteogenesis, a biological pathway that leads to endochondral bone formation, the mode through which the condyle grows. (2) Quantitative analyses revealed the temporal pattern of the expression of these two factors, indicating that the thrust of natural growth of the condyle in the rats occurred in concomitance with somatic pubertal growth, featured by an acceleration starting from day 38, a maximum growth rate on day 56, followed by a decrease afterwards.

CONCLUSION

It is suggested that the biochemical examination of growth markers, such as type X collagen, might be a new approach to accurately depict temporal pattern of condylar growth which is too delicate to be reflected by gross measurement not only in Sprague-Dawley rats but potentially also in other species.

Skeletal effects of bite jumping therapy on the mandible - removable vs. fixed functional appliances

AUTHORS: Shen G, Hagg U, Darendeliler MA.

OBJECTIVE

Based on an extensive review of the literature, the aim of this study was to explore the mainstream consensus on the controversial topic of whether the bite jumping treatment could enhance mandibular growth.

DESIGN

The data for removable and fixed functional appliances were respectively comprehended and analyzed with regard to their attributes in mandibular growth modification. Furthermore, numerous reported findings were assessed by relating them to some important factors influencing the effects of bite jumping, such as treatment timing, treatment duration and post-treatment follow-up, to allow for a more objective and accurate evaluation.

RESULTS

The key differences between removable and fixed appliances are working hours (intermittent vs. continuous), length of treatment time (long vs. short), optimal treatment timing (before puberty growth vs. at or after puberty spurt), and mode of bite-jumping (considerable vertical opening vs. limited vertical opening). These different features lead to different treatment effects on mandibular and TMJ growth, such as the intensity of possibly increased growth (clinically less significant vs. significant), the direction of enhanced growth (vertical vs. horizontal), and the stability of treatment changes (unstable vs. stable). The short-term or long-term post-treatment relapse mainly relates to the rebound of dental position.

CONCLUSION

The immediate effects of bite jumping functional appliances on the mandibular growth enhancement are convincing during actual treatment. This extra gain of growth might be sustainable during the short-term and long-term post-treatment period.

Initial and late treatment effects of headgear-Herbst appliance with mandibular step-by-step advancement

The aim of this study was to investigate the effects of the headgear-Herbst appliance with mandibular step-by-step advancement followed by retention with the headgear activator. The sample comprised 22 consecutively treated patients (13.2 +/- 1.5 years old) and 31 matched controls (12.6 +/- 1.3 years old). Lateral cephalograms were obtained at the beginning of treatment, after 6 months (at completion of the initial phase), after 12 months of active treatment (at the end of the late phase), and after 18 months (at the end of retention). The results showed that the skeletal effects over 12 months of treatment were restrained maxillary growth, enhanced mandibular growth, and reduced increase in lower facial height. The restraint effect on the maxilla was significant in both the initial and late phases; the enhanced growth of the mandible was significant during the initial phase only; and the height of the lower face was affected during the late phase only. During retention with the headgear activator, the jaw base relationship was maintained, and the effect on the lower facial height was reinforced. A small relapse of the overjet and molar relationship was the result of dental changes only. During 18 months of active treatment and retention, the overjet correction was the result of 70% skeletal changes. The headgear-Herbst appliance is an effective orthopedic device, and the effect on the maxilla seems to increase with the length of treatment, but the pattern was reversed for the mandible.