The effect of treatment with the Bass appliance on skeletal Class II malocclusions: a cephalometric investigation

The purpose of this investigation was to study the short-term effects of treatment with the Bass appliance by comparative evaluation of treated and untreated skeletal Class II malocclusions. The subjects consisted of forty-seven Class II, division 1 malocclusion cases. Twenty-seven (14 girls, 13 boys) were treated with the Bass appliance for an average of 6 months. The remaining 20 cases (6 girls, 14 boys) served as a control. At the end of the 6 month treatment period the statistically significant treatment changes could be summarized as follows: the sagittal skeletal relationship was improved as a result of favourable growth responses in both the maxilla and the mandible. The overjet was reduced and the molar relationship was corrected as a result of the extended skeletal changes. Distal movement of the upper dentition was evident, with unchanged inclination of the maxillary incisors. Both anterior and posterior facial heights were increased without changes in the inclinations of the palatal and mandibular planes. No significant dental movement was observed in the mandible.     

A growth control approach to Class II, Division 1 cases during puberty involving the simultaneous application of maxillary growth restriction and mandibular forward induction

A simple method that used headgear and a functional appliance simultaneously was used for the correction of Class II, Division 1 cases with severe denture base discrepancy. The treatment restricted the forward growth of the maxilla and advanced the mandible. The functional appliance, referred to as the mandibular growth advancer (MGA), advances the mandible progressively with a splint, with the objective of remodeling the condyle and the glenoid fossa in the temporomandibular joint. Functional adaptation was achieved as the muscles that are attached to the mandible adjusted to new positions. In the two cases that illustrate this method, the ANB angle decreased and the Ar-B distance increased over a short period to four and six times the mean Japanese growth rate, respectively. After the correction of the denture-base discrepancy, a multibracket fixed appliance was used for dental alignment, and good skeletal, occlusal relationships and profiles were obtained. Treatment of severe denture-base discrepancy in this manner may reduce the skeletal abnormality, decrease the number of extraction cases, and shorten the subsequent multibracket treatment time. And it may reduce the iatrogenic side effects caused by prolonged mechanotherapy with a fixed appliance.     

Treatment response to maxillary expansion and protraction

A prospective clinical trial was conducted to determine the skeletal and dental contributions to the correction of overjet and overbite in Class III patients. Thirty patients (12 males and 18 females with a mean age of 8.4 +/- 1.7 years) were treated consecutively with protraction headgear and fixed maxillary expansion appliances. For each patient, a lateral cephalogram was taken 6 months before treatment (T0); immediately before treatment (T1); and 6 months after treatment (T2). The time period (T1-T0) represented changes due to 6 months of growth without treatment; (T2-T1) represented 6 months of growth and treatment. Each patient served as his/her own control. Cephalometric analysis described by Bj?rk (1947) and Pancherz (1982a,b) was used. Sagittal and vertical measurements were made along the occlusal plane (OLs) and the occlusal plane perpendicular (OLp), and superimposed on the mid-sagittal cranial structure. The results revealed the following: with 6 months of treatment, all subjects were treated to Class I or overcorrected to Class I or Class II dental arch relationships. Overjet and sagittal molar relationships improved by an average of 6.2 and 4.5 mm, respectively. This was a result of 1.8 mm of forward maxillary growth, a 2.5-mm of backward movement of the mandible, a 1.7-mm of labial movement of maxillary incisors, a 0.2-mm of lingual movement of mandibular incisors, and a 0.2-mm of greater mesial movement of maxillary than mandibular molars. The mean overbite reduction was 2.6 mm. Maxillary and mandibular molars were erupted occlusally by 0.9 and 1.4 mm, respectively. The mandibular plane angle was increased by 1.5 degrees and the lower facial height by 2.9 mm. Individual variations in response to maxillary protraction was large for most of the parameters tested. Significant differences in treatment changes between male and female subjects were found only in the vertical eruption of mandibular incisors and maxillary and mandibular molars. These results demonstrate that significant overjet and overbite corrections can be obtained with 6 months of maxillary protraction in combination with a fixed expansion appliance.     

A modified, lingually supported cantilevered Herbst appliance

This new, fixed-functional appliance/Herbst/Bioprogressive system is designed for patient comfort and mandatory compliance. It also combines the positive clinical effects of four fixed-functional systems. It allows rapid palatal expansion of the upper arch, alveolar uprighting of the lower arch, upper and lower incisor alignment, and sagittal correction of Class II malocclusions to occur simultaneously with one appliance fixed in both arches. It is indicated for use in growing patients with skeletal Class II malocclusions. The ideal timing for treatment is the late mixed dentition. Being able to remove the appliance after one year with the upper second bicuspids erupting slightly Class III so the clinician can immediately begin fixed finishing mechanics would be ideal. This new Herbst design will reduce the frequency of orthognathic surgery and upper bicuspid extraction to camouflage Class II malocclusions. At the same time, it gives total control to the clinician in treating some more difficult, non-compliant patients. Fixed-functional appliances, which improve treatment efficiency and treatment results and provide for patient comfort, while at the same time give the treating clinician almost total control of the three planes of facial growth will open new doors for orthodontic treatment and research in the next century.     

Long-term effects of the Herbst appliance on the dental arches and arch relationships: a biometric study

The purpose of this study was to evaluate biometrically the treatment and post-treatment effects of the Herbst appliance on the dental arches and arch relationships. The sample consisted of 53 Class II, division 1 malocclusion patients (33 boys and 20 girls) treated with the Herbst appliance. The mean age of the patients before treatment was 12.5 years (SD = 1.2 years). Dental casts were analysed before treatment, after treatment, 6 months post-treatment and at the end of the growth period (5-10 years post-treatment). The following variables were assessed: sagittal molar and canine relationships, overjet, overbite, maxillary and mandibular arch perimeters, and inter-molar and inter-canine dental arch widths. During treatment, the overjet, overbite, and sagittal molar relationship were overcorrected in most of the cases, while the sagittal canine relationship was normalized. The maxillary and mandibular arch perimeters increased during treatment, as did dental arch widths (molar and canine). In the long-term (mean = 6.7 years after treatment), Herbst appliance treatment resulted in a normal or over-corrected sagittal molar relationship in 79 per cent and a normal canine relationship in 68 per cent of the cases. Eighty-three per cent of the subjects had an overjet of 4.5 mm or less. In the long-term, the arch perimeters seemed to follow a normal dental development pattern. The increase of the upper molar and canine dental arch widths during treatment remained virtually stable whilst the lower intermolar arch widths seemed unaffected by treatment.     

Intermaxillary forces during activator treatment

The mode of action of the activator appliance is still unclear. Apart from a possible mandibular growth enhancing effect, some investigators believe that orthopedic forces may be applied to the maxilla, contributing to Class II correction by inhibition of maxillary growth. In addition, orthodontic forces may arise that produce dentoalveolar changes. The purpose of this study was to measure the magnitude of anteroposterior intermaxillary forces during wear of the activator appliance. Ten consecutive patients with Class II dental and skeletal relationships were treated with a modified activator appliance. The appliance had maxillary and mandibular segments that could be detached from each other during the measuring session. A force transducer was placed at the anterior part of the maxillary segment, and the anteroposterior force exerted by the mandibular segment was measured. Measurements were taken in the upright and reclined position at every patient visit for a period of 6 months. Results indicated that intermaxillary forces were generally in the orthodontic range (median values of 100 gf at the upright position and 123 gf at the reclined position). A wide variation in force levels was noted, both between patients and for the same patient during the experimental period. No statistically significant change in force levels was observed during the 6 month period and no difference was noted between upright and reclined posture.     

Gene expression of trehalase during post-dormant development of the brine shrimp, Artemia: comparison of the two species

The purpose of this article is to summarize the short-term and long-term results of the authors' clinical prospective study on the treatment of Class III malocclusion using the protraction facemask. An attempt is made to answer questions pertaining to this treatment modality. Twenty patients with skeletal Class III malocclusion were treated consecutively with maxillary expansion and a protraction facemask. A positive overjet was obtained in all cases after 6 to 9 months of treatment. These changes were contributed to by a forward movement of the maxilla, backward and downward rotation of the mandible, proclination of the maxillary incisors, and retroclination of the mandibular incisors. The molar relationship was overcorrected to Class I or Class II dental arch relationship. The overbite was reduced with a significant increase in lower facial height. The treatment was found to be stable 2 years after removal of the appliances. At the end of the 4-year observation period, 15 of the 20 patients maintained a positive overjet or an end-to-end incisal relationship. Patients who reverted back to a negative overjet were found to have excess horizontal mandibular growth that was not compensated by proclination of the maxillary incisors. A review of the literature showed that maxillary expansion in conjunction with protraction produced greater forward movement of the maxilla. Maxillary protraction with a 30 degrees forward and downward force applied at the canine region produced an acceptable clinical response. The reciprocal force from maxillary protraction transmitted to the temporomandibular joint did not increase masticatory muscle pain or activity. Significant soft tissue profile change can be expected with maxillary protraction including straightening of the facial profile and better lip competence and posture. However, one should anticipate individual variations in treatment response and subsequent growth changes. Treatment with the protraction facemask is most effective in Class III patients with a retrusive maxilla and a hypodivergent growth pattern. Treatment initiated at the time of initial eruption of the upper central incisors helps to maintain the anterior occlusion after treatment.     

Expansion

Expansion of dental arches has been in practice for a long time and will be around for years to come. Correct diagnosis along with familiarity of the appliance to be used will enhance the results of orthodontic treatment. The NPE incorporates many of the functions that exist in several different appliances. It can be used for maxillary corrections, crossbites, distal rotation and expansion of molars, molar stabilization, auxiliary placement for habit correction, intrusion of molars, three-way Saggital with utility arch, as an aid in Class II correction retainer, etc. It can be used in primary dentition, mixed dentition, adult dentition, cleft palate patients, surgery cases, Class III cases, and TMJ cases. Most patients can benefit from the use of this one appliance. I will continue to use the NPE and possibly discover more uses for it as I work with it.     

A case of bilateral optic neuropathy and recurrent transverse myelopathy associated with perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA)

The purpose of this study was to evaluate skeletal and dental effects of bionator headgear combination appliances on patients in development period with Class II, division 1 malocclusion. The comparison of computerized X-ray cephalometric measurements between the 26 treated children and 26 untreated children was made. The results showed that ANB angle was significantly reduced and horizontal mandibular growth development tended to be normal in the treated group. It was suggested that the bionator headgear combination appliance can restrain the maxillary growth early and promote the forward mandibular growth which contribute the functional jaws correction.     

Longitudinal evaluation of growth changes in Class II division 1 subjects

Longitudinal records from the Ohio State University Growth Study were used to compare the skeletal growth changes between Class II division 1 and Class I female subjects between ages 7 and 14. Tensor analysis was used to determine the yearly growth rate and direction. No significant difference was found in cranial base dimension between the Class I and Class II subjects. In Class II subjects, the maxilla (S-N-A) was found to be normally related to the cranial base. However, mandibular position (S-N-B and S-N-Pog) was found to be significantly more retrusive in Class II when compared with Class I subjects. Mandibular length (Ar-Gn) and corpus length (Go-Gn) were found to be shorter in Class II subjects. The ratio of PFH to AFH was found to be smaller in Class II subjects. This is particularly apparent during the pubertal growth period. The y-axis and mandibular plane angle were more open in Class II subjects which also contributed to the retrusive position of the mandible. Maxillo-mandibular difference (A-N-B) between Class I and II subjects was present at age 7 and persisted through puberty, maintaining a greater angle of convexity (A-N-Pg) in Class II subjects. These results suggest that Class II malocclusion can be detected early. The majority of the Class II cases showed mandibular skeletal retrusion or a combination of horizontal and vertical abnormalities of the mandible rather than maxillary protrusion. These skeletal differences remain through puberty without orthodontic intervention. Individual variations were found within each type of malocclusion.     

The Goettingen "Pro-Stab" removable plate system. A retrospective cephalometric study of the effects of a new Class II treatment appliance

The new removable double-plate appliance has characteristics which provide for efficient treatment of Class II malocclusions: virtually unimpaired speaking and free breathing seem to support patient compliance. The sagittal activation is easy to change and the plates for the upper and the lower jaw can be worn separately or in combination, with and without the "Pro-Stab" rods even with different wearing hours (modular concept). Evaluation of lateral head films taken at the beginning and at the end of treatment (mean interval 1.45 years) of 40 patients provided information on therapy-induced changes, which were then compared with results of recent publications. The data obtained with the new system indicate similar results as with bite-jumping appliances and headgear-supported activators. Inhibition of the sagittal development of the upper jaw and retrusion of the upper incisor segment have been primarily responsible for the correction of Class II malocclusions. The effect as regards the sagittal position of the lower jaw has been moderate. In comparison with similar appliances, protrusion of the lower incisors was more pronounced when treated with the Goettingen Type I "Pro-Stab" removable plate system.     

Magnetic activator device II (MAD II) for correction of Class II, division 1 malocclusions

A magnetically active, two-piece (upper and lower), functional orthopedic appliance has been developed, magnetic activator device (MAD) for the correction of Class II malocclusions. The magnetic forces are used to give freedom of mandibular movement and to allow for continuous functioning of the orofacial muscles when the appliance is worn. Samarium cobalt (Sm2Co17) magnets are incorporated on the buccal aspects of the upper and lower appliances. Magnetic forces ranging from 150 to 600 gm per side have been used on patients, and it seems that the skeletal versus dental response depends on the intensity of the magnetic force used. A force of 300 gm, when the magnets are in contact, on each side has been found to be an appropriate value in patients age 7 to 12 years. The use of this less bulky design rather than a traditional orthopedic appliance, along with the freedom of function it permits, has enabled patients to wear the appliance nearly 24 hours in most cases.     

Usefulness of multiple burr-hole operation for child Moyamoya disease]

The purpose of this study was to examine the cephalometric changes that occur with palatal expansion/facemask therapy for Class III malocclusion. Pretreatment and posttreatment lateral cephalograms from 21 patients were traced and analyzed by traditional cephalometric measures, an x-y coordinate system, and along the functional occlusal plane. Differences between T1 and T2 values were analyzed with paired t-tests. Mean ages were 7.26 years (T1) and 8.18 years (T2). Average treatment time was 11.05 months. Statistically significant anterior movement of the maxilla occurred with increases in SNA (+2.35), maxillary depth (+2.22), and ANB (+3.66), and anterior movement of A-point (+3.34 mm) and ANS (+3.17 mm). The maxilla rotated counterclockwise, with PNS moving down more than ANS (-2.21 mm and -0.82, respectively). The mandible rotated clockwise with mild decreases in SNB (-1.32) and facial depth, (-1.2) but significant downward movement at menton (-4.34 mm). Occlusal plane analysis demonstrated that the correction was due more to the maxilla than the mandible (+2.35 and -1.88 mm, respectively). The maxillary molars moved forward (+1.70 mm) as did the incisors (+1.75 mm). Soft tissue changes included the nose and upper lip moving forward (3.43 and 3.67 mm, respectively), and menton moving downward (-3.49 mm). The results indicate that facemask/palatal expansion therapy improves Class III malocclusion by a combination of skeletal and dental changes that occur the anteroposterior dimension and in the vertical plane of space.     

Morphological changes of the TMJ condyles of 100 patients treated with the Herbst appliance in the period of puberty to adulthood: a long-term radiographic study

One hundred consecutive patients were treated with the Herbst appliance in the period of puberty to adulthood. The orthopaedic effects on the morphology of the condyles were described from orthopantomographic and transpharyngeal radiographs. The orthopaedic treatment effect was, in most cases, visible as a change in morphology of the condyle, a double contour in the distocranial part of the condyle and sometimes also at the distal surface of the ramus. In patients at the peak of puberty, the double contour was distinct for a short time. In patients in late puberty, the double contour could be seen several months after treatment. At adulthood, males showed, in most cases, double contours, while females showed in most cases nearly unchanged condyles. When double contours were seen, these persisted for a few months to several years after Herbst treatment. The newly formed bone was stable and no TMJ problems were observed. The change in morphology and the double contour of the condyle can be interpreted as bone modelling. The newly formed bone on the posterior part of the condyle can be explained as a response to hypertropic chondrocytes, and that on the posterior part of the ramus as a response of resting osteoblasts to mechanically induced changes in the condyle (adaptive bone growth). In two cases, remodelling resorption was found in the anterior part of the condyle after Herbst treatment, again as a sign of adaptation to changed mechanical influence. In both cases, later refilling with bone was registered during the remodelling process. The biomechanical effect of Herbst treatment on the mandible is also analogous with an impeded matrix rotation combined with relocation of the mandible.     

The effects, limitations, and long-term dentofacial adaptations to treatment with the Herbst appliance

The purpose of this article is to summarize the existing scientific data with respect to the short- and long-term effects of the Herbst appliance on the occlusion and on the maxillo/mandibular complex. The article also discusses the treatment indications and possible treatment limitations. The Herbst method is most effective in the treatment of Class II malocclusions. Long-term stability seems to be dependent on a stable cuspal interdigitation. Marked mandibular morphological changes occur during therapy and sagittal condylar growth is increased. Posttreatment, most of the mandibular morphological changes revert and no long-term influence of Herbst treatment on mandibular growth can be verified. The appliance effect on the maxillary complex can be compared with that of a high-pull headgear. Without proper retention, however, this effect is of a temporary nature. Herbst treatment is especially indicated in the permanent dentition at or just after the pubertal peak of growth. Mixed dentition treatment is not recommended, as a stable cuspal interdigitation after therapy is difficult to achieve and relapses are prone to occur. In the nongrowing patient, the appliance should be used with great caution.     

Guiding occlusal development with functional appliances

Functional appliances have been used in orthodontics since their introduction by Pierre Robin almost one hundred years ago, however, our understanding of how they bring about orthodontic correction is still limited. This article is a brief overview of their history, mode of action, advantages and disadvantages, and includes the results of a study of attempts to control and minimise their side-effects using a recent development in functional appliances: the 'Teuscher Appliance'. This appliance combines a high-pull headgear with the activator, and is designed to reduce the often reported side-effects of functional appliances. The skeletal and dentoalveolar effects of treatment with the Teuscher Appliance on 40 consecutively-treated patients are reported and illustrated with four individual case reports. The results showed that the skeletal effect on the maxilla was a retardation of the normal forward and downward growth in 80 per cent of the cases, and that mandibular growth in 70 per cent of cases was forward. In patients whose mandibular growth was primarily in a vertical direction, such growth could be ascribed mainly to posterior rotation of the maxilla and/or the fact that the acrylic covering the lower posterior teeth to correct a deep bite was removed, promoting the eruption of these teeth and increasing the anterior vertical development. The dentoalveolar changes were characterised by retroclination of the maxillary incisors in 90 per cent of the patients, and were due to insufficient torque control by the built-in torque springs, which need further development. The mandibular incisors were well controlled by capping. The statistical analysis showed an inverse correlation between the initial incisor inclination and the change during treatment. This suggests that proclination of the lower incisors, as previously reported, is not a contra-indication to functional appliance treatment, provided the appliance is correctly designed. Overall, this study showed considerable individual response to treatment, and that the occlusal correction occurred through a combination of skeletal and dentoalveolar changes.     

Control of the vertical dimension in Class II correction using a cervical headgear and lower utility arch in growing patients. Part I

A retrospective cephalometric study was performed comparing three groups of 30 growing patients with Class II, Division 1 malocclusions. Group 1 was treated with a cervical headgear/lower utility arch combination (CHG/LUA), group 2 was treated with a cervical headgear alone (CHG), and the third group was untreated. The average treatment time was 1 year, 6 months. No other appliances were used during this period. Maxillary and mandibular dental and skeletal treatment responses were compared with an analysis of variance (ANOVA) and a Scheffe's test. In addition, a multiple stepwise regression was performed to determine whether pretreatment measures of facial pattern were accurate predictors of mandibular rotational response. Both treatment groups demonstrated significant reduction in maxillary protrusion. The CHG-only group showed significantly greater anterior descent of the palatal plane as compared with the untreated group. The maxillary molars showed significant distal movement in both treatment groups without any extrusion beyond that seen with normal growth. The maxillary incisor demonstrated significant retroclination in the CHG-only group. There was no statistical difference among the groups for variables commonly used for measuring mandibular rotation or protrusion. The change in vertical position of the lower molar was not significantly different among the groups. A CHG as used in this study produced maxillary orthopedic and orthodontic changes without upper molar extrusion beyond that seen with normal eruption and in the absence of an opening rotation of the mandible, even in subjects with dolicocephalic facial patterns. The LUA did not appear to influence lower molar eruption or mandibular rotational response. None of the commonly used predictors of facial pattern, such as the Y-axis, XY-axis, or MP angle, accurately predicted mandibular rotational response. Further study would be necessary to ascertain whether this was a result of their invalidation as predictors, or a result of the treatment strategy employed.     

Studies on the hypotensive and bradycardic effects of 1-piperidinylmethyl-2-naphthol hydrochloride

An understanding of growth and development and the effect our appliances have on a person's growth and development is necessary in the selection of the therapeutic appliances we choose to use, out of the multitude available. Timing of treatment is also important in effecting positive changes in skeletal and dental relationships. Early treatment to correct skeletal discrepancies and gain arch length can allow for an increase in nonextraction therapy. Cervical extraoral appliances, maxillary fixed expansion appliances, and mandibular labial "E" arches can be used early to effectively reduce of skeletal discrepancies and to gain arch length without the fear of rotating the mandible down and back, permanently increasing the mandibular plane angle. Case reports are presented to illustrate the beneficial changes that can occur with early treatment with these appliances.     

Dietary factors and risk of lung cancer in never-smokers

The primary purpose of this study was to evaluate the effectiveness of cortical anchorage, by comparing two groups of patients with Class II malocclusions that were treated successfully with Class II elastics. One group of 30 previously treated patients had a utility arch used to set up cortical anchorage in the lower arch before Class II elastic wear; the second group was treated with standard edgewise mechanics where anchorage preparation consisted of full appliances, a well-aligned mandibular arch, and a rectangular arch wire. The groups were selected according to age, sex, and the amount of Class II elastic usage. Pretreatment and posttreatment cephalometric radiographs were used to generate 32 variables. A Student's t test was used to evaluate treatment change between the groups and revealed that there were no statistically significant differences. Lower molar teeth extruded and moved mesially equally in both groups. Although cortical anchorage did not retard lower molar movement, it was no less effective in controlling molar movement with a partial appliance than the fully banded standard edgewise appliance.     

Aging of the population: demographics for the Liege region

We present the case of a 26-year-old man who at the age of 9 suffered severe trauma to both maxillary central incisors. The underlying malocclusion was skeletal and classified as dental Class II/1 with severe crowding. Both the maxillary central incisors and the two lower first premolars were extracted and the patient was treated with an edgewise appliance for 2 years. Acceptable occlusal relationships were achieved following orthodontic and adjunctive treatment which consisted of reshaping the maxillary lateral incisors with composite materials and grinding the canines to resemble lateral incisors. A critical evaluation of the esthetic and functional results at the age of 26 years is presented.