A comparison of different treatment techniques for posterior crossbite in the mixed dentition

An alternative approach for the surgical correction of unilateral crossbite

This case report aims to describe a modified surgically assisted rapid palatal expansion technique to treat an asymmetrical posterior crossbite with no mandibular shift without causing an interincisal diastema. A clinical patient with an asymmetrical crossbite, large tooth-size-arch length, and Bolton discrepancy is used to illustrate the modified technique. Instead of traditional osteotomies, in this technique, the osteotomy is done between the maxillary right canine and lateral incisor (connecting the piriform aperture to the alveolar process) along with a unilateral LeFort I osteotomy. The expansion forces are produced by the activation of a conventional hyrax appliance. The skeletal unilateral crossbite was corrected without major changes to the opposite side and without causing an anesthetic diastema between the maxillary central incisors. A mandibular incisor extraction produced the space needed to treat the tooth size-arch length and corrected the Bolton discrepancy. This allowed a successful treatment of the problems initially presented by the patient.

Short term effects of interceptive expansion treatment: a prospective study

OBJECTIVES

This prospective cohort study investigated the short term effects of interceptive orthodontic treatment with a removable expansion plate, evaluating the changes in occlusion in all its dimensions: transversal, sagittal and vertical.

SUBJECTS AND METHODS

A total of 226 patients treated with a removable expansion plate (slow maxillary expansion, SME) by orthodontic residents at the Department of Orthodontics, University Hospitals Leuven, Belgium were included. The patients had a mean age of 8.5 years at the start of the treatment. The mean treatment time was 6.9 months. Transversal measurements (intercanine and intermolar width) and occlusal characteristics (molar occlusion, overjet, overbite and functional shift) were collected before (T0) and after active treatment (T1). Statistical analysis was performed using the Wilcoxon signed rank test, Sign test and McNemar test for assessing changes between T0 and T1. Linear models were used to assess the associations between patient factors and the amount of expansion.

RESULTS

A significant increase in transversal width at different occlusal landmarks was found. Correction of unilateral, bilateral and frontal crossbites was successful in 99.0%, 95.2% and 93.6% of the cases respectively. Changes in sagittal molar occlusion were significant: 64.9% (right side) and 62.6% (left side) remained stable, 28.4% (right) and 29.3% (left) improved and 6.7% (right) and 8.1% (left) deteriorated. Overbite changes were found to be statistically significant, though clinically irrelevant. Overjet changes were non-significant.

CONCLUSIONS

A removable expansion plate is successful in improving the transversal dental dimensions of the maxilla. Statistically significant sagittal effects on molar occlusion were found. Long-term follow-up is needed to evaluate the long-term stability of this treatment.

A randomized clinical trial to assess the sagittal effects of Transforce transverse appliance (TTA) and NiTi palatal expander (NPE) on skeletal class II malocclusion in growing patients during retention phase - A cephalometric study using a historical control group

OBJECTIVES

To evaluate and compare the skeletal changes during the retention period after expansion with "Transforce Transverse lingual or palatal Appliance®" (TTA) and "NiTi Palatal Expander®" (NPE) in growing subjects with class II division 1 malocclusion and to compare these changes with a matched historical control.

SUBJECTS AND METHODS

A unicentric two arm, parallel randomized clinical trial with additional historical control group was conducted over a period of six years. The subjects in the age group of 9-13 years were screened and recruited as they reported. The inclusion criteria were: late mixed/early permanent dentition, class II or end on molar relationship, posterior transverse inter-arch discrepancy 4-8mm, overjet≥5mm, cephalometrically ANB>4° and CVMI stage CS2-CS3. Subjects were randomly allocated to two study groups (SG), TTA and NPE using block randomization. Appliances in both SG were managed and followed by a single clinician with equal standards of care. The lateral cephalograms in digital form were obtained at the beginning of the treatment (T1), post-expansion (T2) and after ten months retention period (T3). Linear positional change>1mm and angular change>0.75° were considered as a clinically significant change. Due to the ethical reasons a historical control of ten patients (CG) comparable to the SG for age and inclusion criteria was used to rule out the growth changes on serial lateral cephalograms. All Cephalometric measurements were done by a single operator blinded for the group allocation. Operator's measurement error was estimated. The study was single-blinded in regard to statistical analysis. Inter-group comparisons between SG were made by using an unpaired Student's t-test. ANOVA with post-hoc analysis was used for comparison among the study and control groups.

RESULTS

A total of 36 subjects were recruited, 18 in each SG. Average time required to achieve the desired expansion in the TTA and NPE group was 13.6 weeks and 9.8 weeks respectively. The TTA group showed significant increase in SNB (1.54±0.33°) when compared with the control group (0.53±0.37°) and with the NPE group (0.74±0.29°) (P<0.0001). Significant differences were observed when post-retention changes in SNB, ANB, Wits appraisal, and N perpendicular to Pogonion, were compared among the three groups (ANOVA, P<0.0001). Tukey's multiple comparison showed that these mandibular sagittal changes were significantly greater in the TTA group than in NPE and the control group (P=<0.007, Bonferroni corrected value).

CONCLUSION

Cephalometrically significant sagittal advancement of mandible took place after expansion with TTA and NPE compared to untreated control. TTA appears to be more efficient for the sagittal positional changes than the NPE. Additional studies with larger samples are warranted to elucidate individual variations in skeletal response to the expansion protocol with these appliances.

A preliminary 3-D comparison of rapid and slow maxillary expansion in children: A randomized clinical trial

BACKGROUND

This study compared the effects of rapid maxillary expansion (RME) and slow maxillary expansion (SME) using cone-beam computed tomography (CBCT).

AIM

To evaluate the skeletal and dentoalveolar effects produced by two different maxillary expansion protocols.

DESIGN

Eligibility criteria included maxillary transverse deficiencies in children (mean age, 8.18 years old), randomly assigned to either RME or SME. At the outcome analysis phase, a sample of 29 subjects were analysed (RME group, N = 16 and SME group, N = 13). CBCT scans taken before expansion and 6 months later were evaluated. Five posterior and 6 anterior transverse measurements were made at different vertical levels. Treatment changes were analysed using paired t tests; independent t tests were used to compare the two groups.

RESULTS

There were statistically significant (P<.05) increases in maxillary width at the skeletal, alveolar, and dental levels for both groups, with significantly smaller increases at the more superior than inferior levels. The RME group exhibited statistically larger width increases than the SME group for all measures except interorbital width, anterior alveolar process width, and intercanine width. The group differences were greater for anterior than posterior apical base widths.

CONCLUSIONS

Rapid maxillary expansion produced greater orthopaedic effects than slow maxillary expansion, with the greatest effects occurring in the anterior apical base.

Hard- and soft-tissue symmetry comparison in patients with Class III malocclusion

OBJECTIVE

Our aim was to describe hard- and soft-tissue asymmetry in people who have a skeletal Class III malocclusion, and to compare with those without asymmetry. We also performed a regional analysis of a possible correlation between facial soft- and hard-tissue asymmetries.

METHODS

This retrospective study was performed with the use of the computed tomographic scans of 60 subjects. The skeletal Class III subjects were categorized into 2 subgroups: soft-tissue menton deviation ≤4 mm (n = 20) versus >4 mm (n = 20). The Class III groups were compared with a Class I symmetry group (n = 20). Hard and soft tissues were segmented into different morphologic areas and deviation calculated. Pearson correlation coefficients were obtained, and 1-way analysis of variance was conducted for statistical analysis.

RESULTS

The highest deviation in the hard tissues of the Class III asymmetry group was in the corpus region (5.55 ± 3.05 mm), with the second highest in the angulus region (4.70 ± 2.43 mm). The highest average deviation in the soft tissues was seen in the lower cheek (7.04 ± 3.46 mm). In the different study groups, the amounts of asymmetry measured in anatomic structures on the mandible were found to be highly correlated between neighboring structures.

CONCLUSIONS

Clinically and statistically significant differences were found in the anatomic regions located in the middle and lower thirds of the face. There was a medium or high correlation between condyle, coronoid process, ramus, and angulus regions. A low level of correlation was observed between middle face and mandibular asymmetries in hard-tissue upper cheek and lower cheek regions were correlated with different mandibular regions.

Transverse Skeletal Effects of Rapid Maxillary Expansion in Pre and Post Pubertal Subjects: A Systematic Review

OBJECTIVE

The aim of this systematic review was to assess the transverse skeletal effects of rapid maxillary expansion (RME) in pre and post-pubertal subjects.

MATERIAL AND METHODS

Five databases were searched till May 2018; Pubmed, Cochrane, Scopus, Lilacs and Web of science in addition to the manual search of other sources. There were no language restrictions. Methodological Index for Non-Randomized Studies MINORS was used to assess the quality and risk of bias of the trials included.

RESULTS

Six studies were finally included in the qualitative analysis. A meta-analysis wasn't performed due to the heterogeneity of methodologies and outcomes. All of the included studies showed drawbacks in their structure yielding weak evidence. On the short term, RME caused an increase in the maxillary and lateral-nasal widths in pre-pubertal subjects by 3.4 mm and 3.3 mm, and by 2.8 and 2.2 mm respectively in post-pubertal subjects. Although statistically insignificant, the maxillary width increase was more than that of the post-pubertal subjects by 0.6 mm. Over the long term, expansion produced permanent increases in the transverse dimensions of both the dento-alveolar and skeletal components of the maxilla and circum-maxillary structures in pre-pubertal subjects. The post-pubertal subjects presented with a statistically significant increase only in the later-nasal width by 1.3 mm than the untreated controls with no permanent increase in the skeletal maxillary width.

CONCLUSION

The literature is very deficient regarding the use of skeletal age as a reference in the treatment of skeletal crossbites using RME. Only weak evidence exists supporting the increased maxillary and lateral-nasal widths after tooth-tissue borne RME in pre-pubertal subjects, with these effects being less in the post-pubertal ones.

Non-surgical Management of Skeletal Class III Malocclusion with Bilateral Posterior Crossbite: A Case Report

A 16-year-old female patient with skeletal Class III malocclusion and bilateral posterior cross bite complaining of difficulty in chewing was treated orthodontically without surgery (camouflage treatment). The treatment comprised of fixed orthodontic treatment with MBT prescription (0.022˝×0.028˝ slot) using quad helix appliance for bilateral expansion of maxillary arch and Class III elastics for occlusal correction. Post-treatment records showed normal overbite and overjet with acceptable occlusion. So with this treatment strategy of expanding the maxillary arch using a quad helix appliance and use of Class III elastics, we achieved a good result with optimal occlusion.

Combination of expansion and orthognathic surgery in a severe hyperdivergent skeletal Class III malocclusion

Class III malocclusions with a severe hyperdivergent growth pattern are very complex to plan and treat. This case report describes the treatment of an adult with a skeletal Class III malocclusion with a midface deficiency, severe bilateral posterior crossbite, and a severe hyperdivergent growth pattern by a combination of a bonded rapid maxillary expansion appliance and surgical procedure of Le Fort I osteotomy for maxillary advancement.

Comparison between rapid and mixed maxillary expansion through an assessment of arch changes on dental casts

Background

Aim of this retrospective observational study was to compare upper and lower dental changes in patients treated with Rapid Maxillary Expansion (RME) and Mixed Maxillary Expansion (MME), assessed by dental cast analysis.

Methods

Treatment groups consisted of 42 patients: the RME group (n = 21) consisted of 13 female and 8 male subjects with the mean age of 8.8 years ± 1.37 at T0 and 9.6 years ± 1.45 at T1; the MME group (n = 21) consisted of 12 female and 9 male patients with a mean age of 8.9 years ± 2.34 at T0 and 10.5 years ± 2.08 at T1. The upper and lower arch analysis was performed on four dental bilateral landmarks, on upper and lower casts; also upper and lower arch depths were measured. The groups were compared using independent sample t-test to estimate dental changes in upper and lower arches.

Results

Before expansion treatment (T0), the groups were similar for all examined variables (p>0.05). In both RME and MME group, significant increments in all the variables for maxillary and mandibular arch widths were observed after treatment. No significant differences in maxillary and mandibular arch depths were observed at the end of treatment in both groups. An evaluation of the changes after RME and MME (T1) showed statistically significant differences in mandibular arch depth (p<0.001) and maxillary intercanine widths (p<0.05). Differences in maxillary arch depth and arch width measurements were not significant.

Conclusions

RME and MME can be considered two effective treatment options to improve transverse arch dimensions and gain space in the dental arches. A greater lower arch expansion was observed in the MME group, which might be attributed to the “lip bumper effects” observed in the MME protocol.

A randomized controlled trial comparing the quadhelix and the expansion arch for the correction of crossbite

OBJECTIVE

To compare the use of the quadhelix and the expansion arch for the correction of crossbite.

DESIGN

A prospective randomized clinical trial supported by preliminary laboratory measurements. The null hypothesis was that there was no difference in the clinical effectiveness of the two expansion devices in terms of crossbite correction.

SETTING

Queen's Hospital, Burton on Trent and The University of Birmingham, School of Dentistry.

PARTICIPANTS

The first 60 patients on the orthodontic waiting list at Queen's Hospital who required expansion of the maxillary arch as part of the treatment plan were allocated to be treated with either a quadhelix or an expansion arch by random allocation. Twenty-eight and 27 members of each respective group completed the study.

MATERIALS

Commercial quadhelix arches (3M Unitek) and custom-made expansion arches

METHODS

The force produced by the type of expansion arches used in the study was measured in the laboratory to be 1.8 N at 10 mm of expansion. Quadhelix arches of sizes 2 and 3 were found to produce equivalent forces at 5 and 7 mm of expansion respectively. Either expansion device was fitted to the 60 participants according to random allocation and expanded by the standard amount. Intermolar and intercanine expansion was measured after 4, 8 and 12 weeks. Patient opinion was assessed by using a questionnaire.

RESULTS

The quadhelix and the expansion arch were equally effective in producing expansion (p>0.05). After 12 weeks, the two types of archwire had produced mean intermolar expansions of 4.54 and 5.09 mm and intercanine expansions of 1.41 and 2.12 mm, respectively. Both types of arch were reported as uncomfortable by a majority of patients, the quadhelix affected mainly the tongue and the expansion arch the cheeks. The appearance of the quadhelix was disliked by 25% of participants, while 70% disliked the expansion arch.

CONCLUSIONS

The null hypothesis was confirmed. However, the expansion arch had several advantages that made it a cheap alternative to the quadhelix for crossbite expansion, because it can be made and fitted at the chairside.

Comparison between rapid and mixed maxillary expansion through an assessment of dento-skeletal effects on posteroanterior cephalometry

Background

The aim of this study is to compare the dento-skeletal effects of rapid maxillary expansion (RME) and mixed maxillary expansion (MME), assessed on posteroanterior (PA) cephalograms.

Methods

Treatment groups consisted of 42 patients; mean age in RME group (n = 21,13 female and 8 male subjects) was 8.8 years ± 1.37 at T0 and 9.6 years ± 1.45 at T1 and mean age in MME group (n = 21, 12 female and 9 male patients) was 8.9 years ± 2.34 at T0 and 10.5 years ± 2.08 at T1. Seventeen bilateral anatomic landmarks, 16 linear (12 skeletal and 4 dental) and 4 angular measurements were assessed for each patient at T0 and T1. Data from the two groups were compared using independent sample t test (p < 0.05).

Results

At T0, the groups were similar for all examined variables (p > 0.05). Significant and equal increase of lateronasal and maxillary and upper and lower molar widths (p < 0. 01) occurred in both groups at T1. Significant but different increases were observed for maxillary incisal, upper left first molar-lateroorbitale, and maxillary first molar angles (p < 0.001 vs. p < 0.05). Significant increases were reported for upper inter-incisal width apex (p < 0.001) and upper right first molar-lateroorbitale angle (p < 0.05) only in the RME group. At T1, differences in maxillary incisal angle (p < 0.05), upper left first molar-lateroorbitale, and maxillary first molar angles (p < 0.001) were noted.

Conclusions

RME and MME were both effective to increase skeletal transverse dimensions by opening mid-palatal suture in growing patients, while MME was associated with minor dental side effects than RME.

Modified quad helix appliance for thumb sucking and cross bite correction

Digit sucking habit is a learned pattern of behavior commonly seen in children of preschool age. Prolonged digit sucking beyond the preschool age, lead to the development of malocclusion such as anterior open bite, maxillary constriction and posterior crossbite. Treatment strategies include interception of habit and correction of the malocclusion. The present case report describes a modified quad helix appliance used successfully in a 9-year-old child to intercept thumb sucking habit and simultaneous correction of posterior crossbite. The appliance has the advantage of easy fabrication, being versatile and more patients compliant.

Treatment of a severe transverse dental arch discrepancy assisted by 3-dimensional planning

This report describes the treatment of a 16-year-old girl with a severe transverse dental arch discrepancy resulting from a mildly constricted maxillary arch and an overexpanded mandibular arch. The patient had a Class I skeletal relationship, a high mandibular plane angle, a Class III molar relationship, bilateral posterior crossbites, and deviated midlines. A 3-dimensional digital setup was used to assist treatment planning. The digital setup allowed us to evaluate multiple treatment options before deciding on the most suitable one for the patient. The final treatment protocol consisted of extraction of upper second premolars and lower first molars due to enamel hypoplasia. Starting with the leveling and alignment stage of treatment, the maxillary archwires were expanded and the mandibular wires were constricted to correct the transverse discrepancy. An auxiliary expansion arch was used to achieve overcorrection. The active treatment period was 24 months. Proper overbite and overjet, facial balance, and good occlusion were achieved.

Hexa helix: modified quad helix appliance to correct anterior and posterior crossbites in mixed dentition

Among the commonly encountered dental irregularities which constitute developing malocclusion is the crossbite. During primary and mixed dentition phase, the crossbite is seen very often and if left untreated during these phases then a simple problem may be transformed into a more complex problem. Different techniques have been used to correct anterior and posterior crossbites in mixed dentition. This case report describes the use of hexa helix, a modified version of quad helix for the management of anterior crossbite and bilateral posterior crossbite in early mixed dentition. Correction was achieved within 15 weeks with no damage to the tooth or the marginal periodontal tissue. The procedure is a simple and effective method for treating anterior and bilateral posterior crossbites simultaneously.

Reverse quad helix appliance: differential anterior maxillary expansion of the cleft area before bone grafting

Cleft-affected cases present a variable degree of transversal constriction of the maxilla. Our aim is to present a new method for differential expansion of the premaxillary area in unilateral cleft lip and palate-affected patients. The reverse quad helix appliance is made of a 0.036-in stainless-steel wire soldered to 2 bands placed on maxillary deciduous canines or first primary molars (or first permanent premolars). It incorporates 4 helical loops forming an inverse W-arch design. The spring is positioned posterior to the banded teeth; thus, the expansion effect is focused in the anterior maxillary region. A reverse quad helix appliance was activated and cemented in 20 patients for premaxillary expansion. Upper arch width was assessed by means of plaster study models in the anterior and posterior maxillary regions. The mean anterior occlusal expansion achieved by the reverse quad helix (9.60 [±5.24] mm) is statistically significantly larger than that achieved in the posterior region (5.50 [±3.07] mm) (P < 0.0001). The reverse quad helix is an efficient appliance for differential expansion of the anterior maxillary region as a preparatory stage for secondary bone graft procedures in unilateral cleft lip and palate-affected patients.

Effect of rapid maxillary expansion on the dimension of the nasal cavity and on facial morphology assessed by acoustic rhinometry and rhinomanometry

OBJECTIVE: To assess the effects of rapid maxillary expansion on facial morphology and on nasal cavity dimensions of mouth breathing children by acoustic rhinometry and computed rhinomanometry. METHODS: Cohort; 29 mouth breathing children with posterior crossbite were evaluated. Orthodontic and otorhinolaryngologic documentation were performed at three different times, i.e., before expansion, immediately after and 90 days following expansion. RESULTS: The expansion was accompanied by an increase of the maxillary and nasal bone transversal width. However, there were no significant differences in relation to mucosal area of the nose. Acoustic rhinometry showed no difference in the minimal cross-sectional area at the level of the valve and inferior turbinate between the periods analyzed, although rhinomanometry showed a statistically significant reduction in nasal resistance right after expansion, but were similar to pre-treatment values 90 days after expansion. CONCLUSION: The maxillary expansion increased the maxilla and nasal bony area, but was inefficient to increase the nasal mucosal area, and may lessen the nasal resistance, although there was no difference in nasal geometry. Significance: Nasal bony expansion is followed by a mucosal compensation.

Longitudinal evaluation of sEMG of masticatory muscles and kinematics of mandible changes in children treated for unilateral cross-bite

The aim of this study was to evaluate masticatory muscle activity and kinematics of mandible changes in children with unilateral posterior cross-bite (UPXB) after orthodontic treatment, and one year after retention. Twenty-five children with UPXB and functional mandibular shift were evaluated before treatment (mean age 12.5years), after treatment (mean age 14.9years), and one year after retention (mean age 16.8years). The same data were collected in a control group of thirty age-matched normocclusive children. Simultaneous bilateral surface electromyographic (sEMG) activity from anterior temporalis (AT), posterior temporalis (PT), masseter (MA), and supra-hyoid (SH) muscle areas were evaluated at rest, during swallowing, mastication and clenching. Kinematic records of rest position, mandibular lateral shift, swallowing and mastication were analyzed. Results showed a lateral shift of the mandible present at rest. During swallowing, sEMG activity of SH predominated before and post-treatment and retention. High frequency of immature swallowing was maintained post-treatment and retention. During mastication, MA activity increased significantly and its asymmetry was corrected post-treatment. During clenching, cross-bite side AT and MA activity increased significantly posttreatment and remained stable after retention, and MA/AT ratio reversed. These findings reinforce the advantages of treating children with UPXB and functional shift as early as possible.

Comparison of estimated and actual changes in gap widths of expansion screws in plate appliances with 7- and 14-day activation

OBJECTIVE

To determine how gap opening is affected by the activation intervals of expansion screws in removable orthodontic appliances and which gap widths are achievable during therapy.

MATERIALS AND METHODS

In this retrospective study, the increases in gap widths for transverse and distalizing screws activated at 7- and 14-day intervals were calculated. These estimates were based on measurements taken with a caliper of the gap widths of 242 screws integrated in the plates of 137 patients examined during 4-5 follow-up visits over a 6- to 7-month therapy period.

RESULTS

A comparison of the theoretical gap widths that we had estimated with those actually measured revealed for the first time that differences in activation intervals have a statistically significant effect on gap width. The 7- and 14-day activation intervals can lead to a linear or nonlinear increase in gap width that greatly depends on the type of expansion screw. Within the therapy period, transverse screws achieved gap widths as much as twice as wide as those achieved with the distalizing screw.

CONCLUSION

The gap widths are illustrated in graphs and summarized in tables. These values offer practical orientation for clinicians planning and controlling the therapy course, and they can help to prevent "overactivation" with removable expansion plates.

Nonsurgical treatment of an adult patient with bilateral posterior crossbite

A woman with an Angle Class III malocclusion and bilateral posterior crossbites complaining of difficulty in chewing was treated orthodontically without surgery. The treatment comprised asymmetric extractions, a removable mandibular lingual arch constriction appliance to narrow the mandibular arch, and a standard edgewise appliance to align the teeth. Pretreatment, posttreatment, and 1-year follow-up records are shown. With this treatment strategy of constricting the mandibular arch by using a combination of removable and fixed orthodontic appliances, we achieved a good result with optimal occlusion.

Treatment of posterior crossbite comparing 2 appliances: a community-based trial

INTRODUCTION

The aim of this community-based trial was to compare the effectiveness of the quad-helix appliance and removable plates for treating posterior crossbite.

METHODS

Ninety-nine patients were randomly divided into 3 groups: quad-helix, expansion plate, and untreated. All subjects were in the mixed dentition, had posterior crosssbite, no sucking habits, no previous orthodontic treatment, and no Class III malocclusion. The following aspects were evaluated: posterior crossbite correction, maxillary and mandibular intermolar and intercanine expansions, length of treatment, cost-benefit analysis, success rate, and number of complications.

RESULTS

The length of treatment and the costs were higher in the expansion plate group than in the quad-helix group. The success rates were similar for the quad-helix and the expansion plate groups, and the number of complications was higher in the quad-helix group. No self-correction was observed in the untreated group, and relapses occurred in both experimental groups.

CONCLUSIONS

The average treatment time was significantly shorter and 11% less expensive than in the quad-helix group, making it the more cost-effective choice for treatment.

Stability of unilateral posterior crossbite correction in the mixed dentition: a randomized clinical trial with a 3-year follow-up

INTRODUCTION

The long-term stability of posterior crossbite correction in the mixed dentition has not been sufficiently evaluated. Our aim was to compare long-term outcomes in patients with crossbite correction by using matched controls with normal occlusion.

METHODS

After 35 patients were treated for crossbite with a quad-helix or an expansion plate, we used randomized controlled trial methodology to follow them for 3 years posttreatment. All had fulfilled our pretreatment criteria: mixed dentition, unilateral posterior crossbite, no sucking habits, and no previous orthodontic treatment. Transverse relationships, maxillary and mandibular widths, overbite, overjet, arch lengths, and midlines were registered on the study models immediately before and after treatment and at the follow-up 3 years after treatment. The matched control group comprised 20 subjects with normal occlusion and was compared with the first and last registrations for the treated groups.

RESULTS

At follow-up, changes in the treatment groups were equal and stable. The changes were comparable with the control group. All other changes were minor and had no clinical implications. The long-term effect of crossbite correction on midline deviation was unpredictable.

CONCLUSIONS

If crossbite is successfully corrected by the quad-helix appliance or the expansion plate, similar long-term stability is achieved. However, in treated patients, mean maxillary widths never reached those of normal control subjects.

Avaliação do crescimento condilar através de cintilografia óssea em pacientes com mordida cruzada posterior funcional

OBJETIVOS: avaliar a atividade de crescimento condilar em 10 pacientes com mordida cruzada posterior funcional antes e após a correção, usando a cintilografia óssea mandibular. MÉTODOS: os pacientes receberam injeção endovenosa de contraste radioativo (Technesium-99m, difosfato de metileno de sódio). Após duas horas, imagens cintilográficas planares foram realizadas por meio de uma câmera Gama. Imagens laterais da boca fechada, mostrando os côndilos direito e esquerdo, foram usadas. Uma imagem da quarta vértebra lombar também foi usada como referência. RESULTADOS: diferenças estatisticamente significativas não foram encontradas nos valores da taxa de absorção, em ambos os lados, quando os períodos de pré-tratamento e pós-tratamento foram analisados separadamente e também quando os períodos de pré-tratamento e pós-tratamento foram analisados no mesmo lado. Não foram encontradas diferenças na atividade de crescimento condilar em pacientes com mordida cruzada posterior funcional.

Long-Term Effects of Rapid Maxillary Expansion on Nasal Area and Nasal Airway Resistance

Background

Rapid maxillary expansion (RME) may improve the nasal respiratory pattern. This study was performed to evaluate the effect of RME on the nasal cavity by acoustic rhinometry and computed rhinomanometry and to determine nasal and maxillary width by posteroanterior cephalometric radiography, up to 30 months after the orthodontic procedure.

Methods

Twenty-seven children with oral breathing, ranging in age from 7 to 10 years, and with mixed dentition were selected. The children had unior bilateral posterior crossbite involving deciduous canines and the first permanent molars. All subjects were submitted to nasofibroscopy, acoustic rhinometry, and computed rhinomanometry and posteroanterior cephalometric radiography at four different times, i.e., before expansion, immediately, 90 days and 30 months after expansion.

Results

The mean linear left-to-right nasal cavity lateral prominence and left-to-right jugal points cephalometric measures increased considerably after expansion and this increase was maintained throughout the period of evaluation. There was an immediate significant decrease in nasal resistance, up to 90 days after RME, but the nasal resistance increased 30 months after the procedure. The acoustic rhinometry results did not show any difference in values throughout time.

Conclusion

RME significantly increased nasal and maxillary width as measured by frontal cephalometry, but the nasal mucosal effects were more subtle. Also, the influence of RME on nasal resistance was not stable, and nasal resistance values returned to close to the initial ones after 30 months.

Treatment response and stability of slow maxillary expansion using Haas, hyrax, and quad-helix appliances: a retrospective study

INTRODUCTION

In this retrospective study, we evaluated the short- and long-term effects of slow maxillary expansion with Haas, hyrax, and quad-helix appliances on posterior crossbite (PXB) correction stability, and maxillary intermolar width and angulation, in the deciduous or early mixed dentition.

METHODS

The inclusion criteria were models and treatment notes of patients with PXB at the start of treatment (T1), after PXB correction (T2), and at least 2 years posttreatment (T3). Exclusion criteria were craniofacial anomalies, fixed appliance use, or more than 1 expander type. From 312 consecutive expansion patients, 74 Haas, 41 hyrax, and 45 quad-helix subjects were evaluated regarding PXB correction, intermolar width, and angulation and compared with published norms to separate treatment effects from growth. The mean ages at T1, T2, and T3 were 8, 9, and 13 years.

RESULTS

There were no significant differences in PXB correction stability or treatment response at T2 and T3 among the 3 expanders. Expansion increased intermolar width by 5 mm and tipped each molar by 2.3 degrees. At least 2 years after expander removal, molar width decreased by 1.3 mm, and the molars uprighted by 6 degrees. Compared with noncrossbite norms, PXB subjects had narrower intermolar width before treatment and greater width after expansion, and were slightly wider at least 2 years posttreatment. Both younger age at T1 and retainer use resulted in statistically greater intermolar width at T3.

CONCLUSIONS

Eighty-four percent of PXB correction remained with about one third of the initial expansion lost; retainer use and early treatment provided increased intermolar width. Haas, hyrax, and quad-helix appliances were equally effective. Slow maxillary expansion altered the PXB patients' maxillary widths from narrower to slightly wider than the widths of the noncrossbite norms.

Morphologic changes of the palate after rapid maxillary expansion: a 3-dimensional computed tomography evaluation

INTRODUCTION

The purpose of this retrospective study was to estimate the area change of the palate after rapid maxillary expansion (RME) in the early mixed dentition stage by using a 3-dimensional (3D) helical computed tomography (CT) scanning technique. In addition, linear changes in the maxillary arch were evaluated.

METHODS

The treated sample consisted of 43 children (mean age, 9 years 1 month) treated with a bonded RME appliance. The untreated control group consisted of 7 children (mean age, 9 years 3 months). Pretreatment and posttreatment dental casts were evaluated by using 3D helical CT scanning procedures. The Student t test was used to compare the linear, area, and angular differences between the treatment times.

RESULTS

RME produced clinically significant increases in interdental widths across the canines, the deciduous first molars, and the permanent first molars in the maxillary arch. Significant increases in cross-sectional area were observed across the permanent first molars (15.3 mm(2)). There was marked variability in the buccal tipping of the permanent first molars.

CONCLUSIONS

Three-dimensional helical CT scanning is an accurate and cost-effective method of assessing dental cast morphologic changes. It can also provide fast and accurate data acquisition and subsequent analysis.

Maxillary Transverse Discrepancies and Potentially Impacted Maxillary Canines in Mixed-dentition Patients

OBJECTIVE

To investigate the correlation between maxillary transverse discrepancy and the occurrence of impacted canines in patients during the mixed-dentition stage.

MATERIALS AND METHODS

Panoramic radiographs and dental casts were evaluated of randomly selected patients in the mixed dentition. The experimental group consisted of 84 orthodontic patients with a maxillary transverse discrepancy. The control group included 100 orthodontic patients without a maxillary transverse discrepancy. Intermolar widths of the experimental group were measured and recorded. The permanent canines of both groups were placed into a sector classification by using a panoramic radiograph. The experimental group was then analyzed to identify whether these patients had an impacted maxillary canine associated with the transverse discrepancy. The results were further evaluated based on type of impaction (unilateral or bilateral).

RESULTS

Results of this study showed that patients with a transverse discrepancy are more likely to have an impacted canine than those patients without a transverse discrepancy, with the impaction more likely being unilateral. However, patients with a transverse discrepancy do not have a greater likelihood of having a bilateral impaction compared with patients without a transverse discrepancy.

CONCLUSIONS

There appears to be an association between potentially impacted canines and transverse discrepancies. Identification can be made early based on proper panoramic evaluation and clinical detection. If a possibly impacted canine is detected early, appropriate treatment should be taken to minimize complications and avoid definitive impaction.

Evaluation of the treatment changes of functional posterior crossbite in the mixed dentition

INTRODUCTION

Functional posterior crossbite (FPXB) malocclusion is frequently seen in the deciduous or mixed dentition. It is often accompanied by lateral mandibular shift and mandibular midline deviation because of the reduction in the width of the maxillary dental arch. The aims of this prospective study were to examine in detail the morphologic, skeletal, dental, and functional effects of FPXB, and the effects of maxillary expansion treatment with quad-helix appliance.

METHODS

The experimental group consisted of 35 FPXB patients (20 girls, 15 boys) having a mean age of 10.6 +/- 1.4 years; the control group consisted of 31 normocclusive subjects (18 girls, 13 boys) with a mean age of 9.8 +/- 1.6 years. Lateral, posteroanterior, and submentovertex cephalograms, transcranial temporomandibular joint radiographs, joint vibration analysis, and electromyographic recordings were obtained from every patient before and after maxillary expansion. Magnetic resonance images were taken before treatment for diagnostic purposes. These data were collected at 1 time point in the controls.

RESULTS

The pretreatment posteroanterior, submentovertex, and transcranial temporomandibular joint radiographs showed mandibular asymmetry relative to the cranial base and condylar malpositioning in the glenoid fossa. Joint vibration analysis findings showed different vibrations between the crossbite and noncrossbite sides, and imbalanced electromyographic findings in the experimental group. After treatment, the asymmetric morphology and position of the mandible and condyles were eliminated, and the stomatognathic system functions were normalized.

CONCLUSIONS

Early orthodontic treatment of FPXB creates optimum conditions for normal growth of the craniofacial skeleton and normal function of the stomatognathic system.

Three palatal arches used to correct posterior dental crossbites

OBJECTIVE

To assess the force, resilience, and elasticity modulus produced by the Coffin appliance, "W" arch, and quad-helix made with 0.032-inch and 0.036-inch stainless steel wire.

MATERIALS AND METHODS

Two groups of 15 arches were made as Coffin appliances, two groups of 15 arches were made as "W" arches, and two groups of 15 arches were made as quad-helices. One group of each appliance was formed in 0.032-inch and one group in 0.036-inch stainless steel wire. All arches (6 groups of 15 each) were submitted to compression trials in the mechanical testing machine EMIC DL-10000, simulating 5-, 8-, 10-, and 12-mm activation. The force and resilience means received a one-way ANOVA statistical analysis.

RESULTS

The results showed that the mechanical properties depended on the shape of the appliance, the diameter of the wire used, and the amount of activation.

CONCLUSIONS

The three appliances assessed produce appropriate forces for orthodontic treatment as long as they are correctly planned during clinical application.

A long-term evaluation of the mandibular Schwarz appliance and the acrylic splint expander in early mixed dentition patients

INTRODUCTION

The aim of this prospective longitudinal clinical study was to evaluate the short-term and long-term changes in dental-arch dimensions in patients treated with either an acrylic splint rapid maxillary expander alone (RME-only) or a rapid maxillary expander combined with a mandibular removable Schwarz plate (RME-Sz) in the early mixed dentition, followed later by fixed appliances in the permanent dentition.

METHODS

The dental casts of 27 RME-only patients were compared with those of 23 RME-Sz patients and 16 untreated controls (CTRL) with constricted maxillary arches at 4 times: pretreatment (T1), after expansion but before fixed appliance therapy (T2), after fixed appliance therapy (T3), and at long-term observation (T4). The mean ages for the treated groups were approximately 9 years at T1, 12 years at T2, 14 years at T3, and 20 years at T4. Arch width, arch depth, arch perimeter, and molar angulation were assessed in all subjects at all observation times. T1-T2, T2-T3, T3-T4, and T1-T4 changes were compared statistically in the treated groups with respect to the CTRL.

RESULTS

Treatment with an RME-only or an RME-Sz followed by fixed appliances produced significant short-term and long-term increases in maxillary arch widths compared with the CTRL. The RME-Sz led to significantly more favorable results than the RME-only protocol: (1) significantly greater increases in the transverse width of the mandibular arch and mandibular arch perimeter in the long term, and (2) uprighting of the mandibular posterior teeth buccally, thus allowing for an amount of maxillary expansion that was clinically effective for the correction of moderate tooth size-arch size discrepancies. In the overall observation interval, the significant increases in maxillary and mandibular arch perimeters in the RME-Sz group were 3.8 and 3.7 mm, respectively, when compared with the CTRL. The RME-only protocol produced modest long-term increases in maxillary arch perimeter (2.6 mm); the average long-term increase in mandibular arch perimeter (2.0 mm) in the RME-only group was not statistically significant.

CONCLUSIONS

The RME-Sz led to significantly more favorable results than the RME-only protocol.

Avaliação transversal e vertical da maxila, após expansão rápida, utilizando um método de padronização das radiografias póstero-anteriores

OBJETIVO: na presente pesquisa utilizou-se o aparelho Hyrax tendo como objetivo avaliar as alterações transversais e verticais da maxila. Foram selecionados 20 pacientes de ambos os gêneros, entre 7 e 11 anos de idade, que apresentavam mordida cruzada posterior uni ou bilateral. METODOLOGIA: foram realizadas telerradiografias em norma frontal (PA) antes e após a expansão. A fim de evitar que a falta de padronização dessas radiografias pudesse influenciar nos resultados, idealizou-se um método de padronização para tais radiografias. RESULTADOS E CONCLUSÕES: os resultados mostraram que a correção da mordida cruzada posterior com o aparelho Hyrax, que ocorreu em todos os casos, foi em função tanto da abertura da sutura palatina mediana como também da inclinação dos molares. A medida JgE-JgD relacionada com a expansão maxilar aumentou significantemente em todos os casos tratados. Nas avaliações dentárias, as medidas verticais não apresentaram diferenças significantes, ao contrário das medidas transversais (FTE-FTD; FBE-FBD; LO.BTE; LO.BTD; BTE.BTD). A largura da cavidade nasal também aumentou significantemente (CNE-CND). O método de padronização proposto permite, portanto, utilizar as medidas que avaliam a expansão rápida da maxila, através das radiografias póstero-anteriores, com segurança, também no sentido vertical.

Asymmetric maxillary expansion (AMEX) appliance for treatment of true unilateral posterior crossbite

The aim of this study was to evaluate the effects of an asymmetrical maxillary expansion (AMEX) appliance. Patients with true unilateral posterior crossbites were included in the study. The treatment group consisted of 18 patients who had a mean age of 14 +/- 2.3 years. Treatment effects were evaluated on posteroanterior radiographs, dental casts, and photographs of the dental casts. All unilateral posterior crossbites were corrected in a mean expansion treatment time of 3.3 +/- 0.48 months. As a result of expansion, maxillary interfirst molar, interfirst and second premolar, and intercanine arch widths increased significantly. Comparison of the 2 sides showed that the teeth on the crossbite side moved and tipped more buccally than the teeth on the noncrossbite side. Of the total expansion gained, 75.8% to 91.7% was due to the buccal movements of the teeth on the noncrossbite side. The AMEX appliance was found to be effective in correcting true unilateral posterior crossbites, and therefore it can be recommended for clinical use.