The stability of the arch-expansion effects of Fränkel appliance therapy

Skeletal and dental effects of function-generating bite appliance compared to rapid palatal expander and untreated controls

INTRODUCTION

Maxillary expansion is a fundamental interceptive orthodontic treatment, which can be achieved through either a rapid expansion protocol or functional devices. However, no data exist about the efficacy of functional devices in achieving skeletal expansion. Therefore, the aim of this study was to compare the effects of the rapid palatal expander (RPE) and the function-generating bite type M (FGB-M) on the transversal dimension of the maxilla, and on the maxillary and mandibular dental arch width.

METHODS

One hundred eighty-one skeletal Class I patients, aged between 6 and 12 years and with a cervical vertebral maturation stage II or III, with maxillary transversal deficiency were retrospectively enrolled; among these 55 were treated with FGB-M, 73 were treated with RPE and 51 were untreated subjects retrieved from historical databases. The pre-treatment (T0) and post-treatment (T1) frontal cephalograms were retrieved, and the maxillary and mandibular widths, and the distance between upper and lower first molars were measured. T1-T0 interval was of 17.3 months (RPE), 24.6 months (FGB-M) and 18.2 months (controls).

RESULTS

The statistical analysis showed that there were no statistically significant differences between the RPE and FGB-M groups regarding skeletal and dental expansion, while the untreated control group differed significantly from the other two groups.

CONCLUSION

The comparison between patients treated with RPE and FGB-M showed that there were no statistically significant differences between the RPE and FGB-M groups regarding the amount of skeletal expansion and dental arch width, suggesting that both appliances can be used to achieve similar results.

Comparison of Changes in Intraoral Dynamic Space (Donders Space) with Myofunctional Therapy in Skeletal Class II Division 1 Malocclusion: An In Vivo Study

AIM

To evaluate the changes in the intraoral dynamic space with myofunctional therapy in skeletal class II division 1 malocclusion using three-dimensional digital volume tomography (3D-DVT).

MATERIALS AND METHODS

The study type is observational and the duration of intervention was 3 years. Dental casts obtained from 20 samples of 11-14 years age-group were collected and 3D-DVT scans were performed prior to and after the myofunctional therapy. The parameters depicting the arch perimeter, arch width, arch length, arch shape, and arch volume on dental cast were used in the study using several linear and volumetric measurements. All parameters were compared before and after myofunctional therapy using t-test.

RESULTS

The Intraoral volume before myofunctional therapy (T0) was 5.59 mL and after myofunctional therapy (T1), it was 7.22 mL. Significant changes were seen in intraoral volume, arch perimeter, arch length, and intercanine and intermolar arch width and the arch shape. Linear and volumetric measurements were increased after myofunctional therapy.

CONCLUSION

Myofunctional appliances lead to an expansion in the anteroposterior and sagittal direction thus increasing the Donders space and leading to proper formation of dental arches and proper positioning of the teeth.

CLINICAL SIGNIFICANCE

Myofunctional therapy is an effective method of increasing arch width, length, and volume. This therapy can be used in routine practices in young children with constricted arch and improvement in facial esthetic.

Transverse maxillary and mandibular growth during and after Bionator therapy: study with metallic implants

INTRODUCTION: This study evaluated posteroanterior cephalograms before and after treatment and long term follow-up of Class II division 1 patients treated with bionator. OBJECTIVE: The objective was to demonstrate the transverse growth of maxilla and mandible during and after bionator therapy. METHODS: Measurement of transverse dimensions between posterior maxillary and mandibular implants, as well as the distances between the buccal, gonial and antegonial points were recorded. Measurements were analyzed at three periods: T1 = before bionator therapy, T2 = after bionator therapy and T3 = 5.74 years after T2. RESULTS: There was statistically significant transverse increase due to growth and/or treatment for all variables, except for the distance between the anterior maxillary implants. CONCLUSIONS: During the study period only the anterior maxillary area did not show transverse growth.

Relapse of incisor crowding: a visit to the Prince of Salina

The management of the retention period after comprehensive orthodontic treatment is of great importance, as a primary goal of clinician. Considerable controversy still surrounds the problem of stability after the retention period. Many studies analyze factors associated to the presence of crowding or incisor irregularity and find predictive features on its relapse. Most studies have reported little o no correlation between the treatment changes in the biological parameters - clinical, biometric (irregularity index, intermolar width, intercanine width, arch length, overjet, overbite), or cephalometric variables- that ocurred and the posttretament and postretention changes that may predict their future development. This article provides a bibliographical overview on the relapse of dental alignment in treated cases. In a brief historical introduction, the first studies on the long-term stability of orthodontic results are analysed. The article then goes on to assess studies that focus attention on anteroinferior alignment before finally studying relapse of upper crowding. It concludes by making some final comments in the light of the bibliography provided and the differents schools regarding retention needs and methods.

Stability evaluation of occlusal changes obtained with Fränkel's Function Regulator-2

OBJECTIVE: To analyze the stability of occlusal changes promoted by the Frankel's Functional Regulator 2 (FR-2), in a mean period of 7.16 years post treatment. METHODS: Fifty-four pairs of models were evaluated, from 18 patients treated with FR-2. All patients had Class II, division 1 malocclusion, with initial mean age of 10.77 years and were treated with FR-2 for 18 months. The models were evaluated at the beginning of treatment (T1), at the end (T2) and after 7.16 years post treatment (T3). For occlusal evaluation, the treatment priority index (TPI) was applied on the three analyzed phases. The alterations that occurred between phases were verified with one another through paired Student's t test, with critical value of 0.05. RESULTS: A statistically significant reduction of TPI was verified, from the initial to the final phase of the treatment, reflecting the efficiency of treatment performed with FR-2, specially due to improvement in molar relation, overjet and overbite. Apart from this, the Class II correction remained stable over time. CONCLUSIONS: In this way, it is concluded that the FR-2 appliance showed to be efficient for the dental correction of Class II malocclusion, with stable occlusal results after 7.16 years post treatment.

The buccinator during mastication: A functional and anatomical evaluation in minipigs

OBJECTIVE

The buccinator muscle forms the lateral wall of the oral cavity. It is presumed to aid mastication by maintaining bolus position. Such a function would involve thickening the cheek, possibly compressing the alveolar bone and contributing to malocclusions. However, neither buccinator deformation nor its effect on pressure has been demonstrated. Our objective was to evaluate buccinator EMG during feeding, its changes in length and thickness, and the pressure exerted on its alveolar attachment, using miniature pigs as an animal model.

METHODS

EMG of the buccinator and other oral muscles was recorded with fine-wire electrodes. Anteroposterior length and mediolateral thickness of the buccinator were evaluated with implanted sonomicrometry crystals, and pressure was measured by flat transducers placed beneath the mandibular origin of the buccinator. Recordings were made during feeding and muscle stimulation. Tissues were collected postmortem for histology.

RESULTS

During mastication, buccinator EMG showed regular peaks that preceded those of the jaw closers. Pattern differences clearly distinguished working and balancing sides. The buccinator shortened and thickened when it contracted. Positive pressures were observed at the mandibular attachment of the buccinator, increasing when the muscle was active. Histological evaluation showed a complex interweaving of fibres closely associated with salivary tissue.

CONCLUSIONS

Buccinator contraction does thicken the cheek, and during mastication this activity takes place just as the closing stroke begins. In addition to controlling the bolus, there may be an effect on salivation. Despite the fact that the muscle pulls on its attachment, the local mechanical environment at the alveolar bone is one of positive pressure.

Nonextraction Treatment with Rapid Maxillary Expansion and Mandibular Symphyseal Distraction Osteogenesis and Vertical Skeletal Dimensions

OBJECTIVE

To investigate the effects of rapid maxillary expansion (RME) and mandibular symphyseal distraction osteogenesis (MSDO) on vertical dimensions of the face.

MATERIALS AND METHODS

Fourteen patients, nine girls and five boys, underwent RME and MSDO procedures. Distraction was carried out at a rate of 1 mm per 24 hours with a tooth-borne appliance. The amount of distraction was 7 mm for each patient. Standardized lateral cephalograms were taken at the following time periods: before treatment (T0), after RME (T1), at the completion of MSDO (T2), and at the end of fixed orthodontic treatment (T3). The data were evaluated by using a general linear model of repeated-measures analysis of variance and paired t-tests at the 95% confidence level.

RESULTS

RME significantly increased the vertical dimensions of the face and decreased the overbite (P < .001). Although the vertical parameters of the face on the lateral cephalogram decreased after MSDO, these decreasing effects were statistically insignificant just for the distances measured from the horizontal reference line to the chin points. In other words, MSDO decreased the vertical skeletal dimensions that were increased by RME, but this neutralizing effect of MSDO was not as much as the increase caused by RME.

CONCLUSION

Treatment modalities (RME, MSDO, and fixed orthodontic treatment) described in this study, in total, had little effect on the vertical skeletal measurements of the face.

Long-term skeletal and dental effects of mandibular symphyseal distraction osteogenesis

The purpose of this study was to evaluate the effects of mandibular symphyseal distraction osteogenesis using a tooth-borne expansion device. The sample included 20 Hispanic nonsyndromic patients (11 males and 9 females) between 13.5 years and 37.3 years of age. Predistraction (1.5 months before surgery), postdistraction (1 month after surgery), and long-term follow-up (1.3 year after surgery) records included posteroanterior, lateral, and panoramic radiographs and models. Postdistraction radiographic evaluation showed that symphyseal distraction osteogenesis produced insignificant increases in the bicondylar, bigonion, and biantegonion widths; intermolar and, especially, intercanine widths increased significantly and a distraction gap was observed in the symphyseal region. Follow-up model analysis showed the largest width increases between the first molars and second premolars and the smallest width increases between canines and first premolars. The difference between the postdistraction and long-term follow-up width changes was explained by the postdistraction orthodontic effect, which modified the shape of the dental arch. A disproportionate pattern of distraction, characterized by significantly greater dental than skeletal widening, was observed in the second molar and antegonion region. Distraction osteogenesis without presurgical orthodontic treatment produced significant proclination of the mandibular incisors; no proclination was observed in cases with predistraction orthodontic treatment. Dental crowding was resolved by the movement of teeth into the distraction regenerate and concomitant orthodontic treatment. Follow-up radiographs showed transverse skeletal stability of the distraction procedure. We conclude that mandibular symphyseal distraction osteogenesis increased mandibular arch width and partially corrected dental crowding, with a potential for disproportionate distraction patterns and proclination of the mandibular incisors.

Expansion with vestibular shields: an experimental test of the periosteal-pull hypothesis

Two mechanisms are said to be responsible for the expansion commonly produced by buccal shields: (1) unbalanced tongue pressure and (2) periosteal pull; that is, periosteal traction on the bone overlying the molar roots. The present study used 44 young albino rats to examine these two alternatives. Half the rats wore buccal shields to produce molar expansion, and half had their maxillary molar crowns ground down to the gingiva to eliminate the effect of the tongue. In the resulting 2 x 2 design, four experimental groups were formed: (1) SM, shields and intact molars; (2) Sm, shields and reduced molars; (3) sM, no shields and intact molars; and (4) sm, no shields and reduced molars. It was hypothesized that if vestibular shields produce expansion through periosteal traction, the presence or absence of molar crowns should make no difference. Conversely, if the expansion is caused by unbalanced tongue pressure, shields should have an effect only in conjunction with intact maxillary molars. Palatal amalgam implants and dorsoventral cephalograms were used to measure the maxillary basal and dental expansion that occurred during the 6 weeks of the experiment. Analysis of variance showed the presence of highly significant interaction between shields and molars: the shields produced an increase in posterior dental expansion, but only when molar crowns were present. In contrast, basal expansion was unaffected by any combination of treatments. At least for the rat, it may be concluded that unbalanced tongue pressure, rather than periosteal traction, is probably responsible for the expansion produced by buccal shields.

Arch width and form: a review

A study of the literature reveals a variety of opinions on the potential for change in arch dimensions. The variations in sample sizes, treatment mechanics, and retention regimens may obscure relevant findings. These articles confirm some common findings, and a number of clinical cases are presented to illustrate these trends. It would seem that limited degrees of arch expansion can be produced regularly, but careful case selection is necessary. Arch expansion is most likely to be achieved in the growing patient with correction of crossbites, correction of a Class II malocclusion, and achievement of a good intercuspation without extractions.

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.

Three-dimensional diagnosis and management of Class II malocclusion in the mixed dentition

Class II malocclusion is a commonly observed problem, occurring in about one third of the United States population. The numerous treatment approaches that have been advocated to treat this malocclusion presumably produce differing treatment effects within the skeletal, dentoalveolar, and soft tissue components of the face. In the first section of this article, the three-dimensional components of Class II malocclusion are described, with transverse maxillary discrepancy, mandibular skeletal retrusion, and increased lower anterior facial height observed as common findings in a mixed dentition sample of Class II subjects. Second, the literature concerning two seemingly diverse treatment methods (extraoral traction and functional jaw orthopedics) is reviewed in detail. Last, cephalometric data are presented from a retrospective clinical study and is used to evaluate the treatment effects produced by cervical traction and the FR-2 appliance of Fränkel in comparison with an untreated sample of mixed dentition Class II patients. The results of this study indicated that although both skeletal and dentoalveolar components of Class II, Division 1 malocclusion were altered in the Class I direction by either a facebow or a Fränkel appliance, these two appliance systems accomplished the correction in dramatically differing ways. Cervical traction affected the skeletal and dentoalveolar components of the maxilla and mandible, whereas the FR-2 appliance had less of an effect on maxillary and dentoalveolar components and a greater effect on mandibular length. Thus, these two treatment modalities produce decidedly different treatment effects in patients with Class II malocclusions.

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.

Changes of arch width in the early treatment of Class II, division 1 malocclusions

Changes in arch width during the early correction of Class II, Division 1 malocclusions with either the Fränkel functional appliance or headgear are compared in an ongoing prospective randomized clinical trial. The data were collected from 43 children, ages 7.5 to 12.85 years, who met strict dental and cephalometric criteria for inclusion in the study. They were assigned at random to treatment with either a headgear (n = 21) or a Fränkel appliance (n = 22). Occlusal measurements included the maxillary and mandibular intermolar distances (buccal and palatal/lingual) and intercanine distances. Measurements (millimeters) were performed on casts taken every 2 months, with digital calipers accurate to 0.01 mm. Four months after the initiation of treatment, the mean maxillary intermolar distance was larger in the Fränkel group (palatal: 1.58, SE: 0.22; buccal: 1.58, SE: 0.20) than the headgear group (palatal: -0.39, SE: 0.21; buccal: 0.26, SE: 0.23), and the difference was statistically significant (palatal: p < 0.0001 and buccal: p = 0.0001). The mean maxillary intercanine distance increased more with the headgear (1.62, SE: 0.19) than the Fränkel appliance (0.62, SE: 0.23) p = 0.003. As treatment progressed, the average intermolar distance in the headgear group increased, but was still higher in the Fränkel group by more than 1 mm. The intercanine distance remained larger in the headgear group. The mandibular intermolar and intercanine distances were higher after Fränkel therapy than with headgear.(ABSTRACT TRUNCATED AT 250 WORDS)