Skeletal and functional effects of treatment for unilateral posterior crossbite

"Association between posterior unilateral functional crossbite and asymmetrical spinal flexion: A prospective study"

Background

Unilateral posterior crossbite (UPC) with functional shift is a malocclusion that may have the potential to affect the masticatory function and the flexibility of the spine due to intrinsic occlusal, structural and functional asymmetries sustained by marked asymmetrical muscular activation.

Research question

To investigate whether the presence of UPC with functional shift is associated with reverse chewing pattern and altered spine flexion.

Methods

Patients with UPC and a control group of patients with normal occlusion were recorded when chewing soft and hard boluses using a Kinesiograph (Myotronics-Noromed Inc., USA) and spine alignment was assessed with an electronic inclinometer Spinal Mouse® system (Idiag AG, Switzerland).

Results

There were 87 children with UPC in the patients' group among whom 38, with median (IQR) age 8.0 (7.3-9.3) years, had measurements before and after treatment. The UPC patients showed a higher percentage of anomalous/reverse chewing patterns on the crossbite side compared with a control group (p < 0.001). Moreover, a clear difference was observed between left and right flexion angles of the spine in the patients' group (p < 0.001 and p = 0.001, paired t-test) with the crossbite side being more flexible compared to the non-crossbite side. No such differences were seen in the control group, nor post-treatment for right and left crossbite (p = 0.44 and p = 0.15 respectively, paired t-test).

Significance

This study suggests an association between UPC, asymmetrical chewing patterns and asymmetrical flexion of the spine. These results may help improve understanding of any association between dental malocclusions and spine posture and hence aid diagnosis and treatment strategies.

Does Orthodontic Treatment Change the Preferred Chewing Side of Patients with Malocclusion?

Whether orthodontic treatment can change the preferred chewing side (PCS) is unknown. This study examined (1) if the PCS changes after orthodontic treatment and (2) which factors contribute to this change. Two hundred fifty patients who visited the orthodontic clinic at Tokyo Medical and Dental University Hospital between 2017 and 2020 were included in the study. Mandibular kinesiograph (MKG) was taken at pre- and post-treatment, and PCS was determined. Patients who showed a change in PCS to the opposite side and those who showed no change in PCS at post-treatment were pooled into the PCS-changed and PCS-unchanged groups, respectively. The demographic, clinical, and cephalometric parameters were compared between the groups. Significant factors associated with changes in were of age < 20 years at the beginning of orthodontic treatment (odds ratio (OR), 2.00), maximum lateral mandibular movement to PCS ≥ 10.0 mm at pre-treatment (OR, 6.51), and change in occlusal canting of ≥1.0° (OR, 2.72). The predicted probability of change in PCS was 13.2%, 36.0%, and 67.5% for no factor, one factor, and two factors associated with PCS change, respectively. Orthodontic treatment may change PCS due to patient age, maximum lateral mandibular movement to PCS, and change in occlusal canting.

Biomechanical evaluation of the unilateral crossbite on the asymmetrical development of the craniofacial complex. A mechano-morphological approach

BACKGROUND AND OBJECTIVE

The occlusion effect on the craniofacial development is a controversial topic that has attracted the interest of many researchers but that remains unclear, mainly due to the difficulties on measure its mechanical response experimentally. This mechano-morphological relationship of the craniofacial growth is often explained by the periosteal and capsular matrices of the functional matrix hypothesis (FMH); however, its outcomes have not been analytically demonstrated yet. This computational study aims, therefore, to analytically demonstrate the mechano-morphological relationship in the craniofacial development of children with unilateral crossbite (UXB) using the finite element (FE) method.

METHODS

The craniofacial complex asymmetry of ten children, five of whom exhibit UXB, was 3D-analysed and compared with the biomechanical response computed from a FE analysis of each patient's occlusion. Due to the complexity of the geometry and the multitude of contacts involved, the inherent limitations of the model were evaluated by comparing computed occlusal patterns with those recorded by an occlusal analysis on 3D printed copies.

RESULTS

Comparison's outcomes proved the reliability of our models with just a deviation error below 6% between both approaches. Out of validation process, computational results showed that the significant elongation of mandibular branch in the contralateral side could be related to the mandibular shift and increase of thickness on the crossed side, and particularly of the posterior region. These morphological changes could be associated with periodontal overpressure (>4.7 kPa) and mandibular over deformation (0.002 ε) in that side, in agreement with the periosteal matrix's principles. Furthermore, the maxilla's transversal narrowing and the elevation of the maxillary and zygomatic regions on the crossed side were statistically demonstrated and seem to be related with their respective micro displacements at occlusion, as accounted by their specific capsule matrices. Our results were consistent with those reported clinically and demonstrated analytically the mechano-morphological relationship of children's craniofacial development based on the FMH's functional matrices.

CONCLUSIONS

This study is a first step in the understanding of the occlusion's effect on the craniofacial development by computational methods. Our approach could help future engineers, researchers and clinicians to understand better the aetiology of some dental malocclusions and functional disorders improve the diagnosis or even predict the craniofacial development.

The effectiveness of the early orthodontic correction of functional unilateral posterior crossbite in the mixed dentition period: a systematic review and meta-analysis

Objective

This systematic review and meta-analysis aimed to critically appraise the available evidence of the effectiveness of early intervention of functional unilateral posterior crossbites (FPXB) between the ages of 6 and 12 years.

Materials and methods

Electronic search in four databases (PubMed, Scopus, Embase, and Google Scholar) for randomized controlled trials (RCTs) and controlled clinical trials (CCTs) was performed between 1^st January 1990 and 31^st October 2021. Methodological index for non-randomized studies (MINORS) for CCTs and Cochrane's risk of bias tool for RCTs were applied. The certainty of the evidence was evaluated according to the grading of recommendations, assessment, development, and evaluation (GRADE) approach.

Results

Nine studies (6 RCTs and 3 CCTs) were included in this review, and six of them were appropriate for quantitative synthesis. The meta-analysis revealed that the quad-helix (QH) was more effective than expansion plates (EP) in increasing the intermolar width (WMD = 1.25; 95% CI 0.75, 1.75; P < 0.001), and decreasing treatment time (WMD = − 3.36; 95% CI − 4.97, − 1.75; P < 0.001). The relapse rate at 5.6 years post-treatment was greater in the QH group than in the EP group (RR = 3.00); however, the difference was statistically insignificant. There was no significant difference between the QH and the EP in other outcome measures. When assessing the rapid maxillary expansion (RME), only one RCT compared the RME with an untreated control group and reported a significant increase in the maxillary intermolar and intercanine width (P < 0.001, P = 0.002, respectively) and a significant decrease in lower midline deviation (P < 0.001).

Conclusion

There is weak to moderate evidence that the treatment of functional posterior crossbite (FPXB) by the QH increased the maxillary intermolar width and the success rate and decreased the treatment duration compared to the EP. The relapse percentage was greater in the QH group. There is very weak evidence that the mandibular midline correction rate did not differ significantly between the QH and the EP modalities. The RME using the Hyrax appliance corrected the FPXB successfully; however, the strength of evidence in this regard is very low. As the quality of evidence ranged from very low to moderate in this review, we confirm the need for more RCTs with different expansion appliances in the early treatment of FPXB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40510-022-00398-4.

Evaluation of the three-dimensional (3D) position of cervical vertebrae in individuals with unilateral posterior crossbite

OBJECTIVE

To evaluate the three-dimensional (3D) position of the cervical vertebrae of growing subjects with unilateral posterior crossbite (UPC).

MATERIALS AND METHODS

In this cross-sectional study, cone beam computed tomography (CBCT) scans of 1455 patients were screened, and ultimately 58 scans (26 patients with UPC and 32 controls with normal occlusion) were included after imposing inclusion/exclusion criteria. Roll, yaw, and deviation of the geometric center of C1, C2, and C3 vertebrae were measured and compared between groups. A correlation between these parameters and different variables on mandibular positioning was also carried out.

RESULTS

A statistically significant difference (p < 0.05) was observed between groups for the deviation of pogonium (Pog), mandibular plane roll, and C3 roll, and patients with UPC showed higher cant or deviation. A significant correlation was reported for the roll of C2 and C3 with the deviation of Pog, a roll of the occlusal plane, and roll of the mandibular plane (p < 0.05). The greater the deviation of the Pog to one side, the greater the roll of the vertebrae with this same side up. The same tendency was observed between the roll of the occlusal plane or the mandibular plane with the roll of these cervical vertebrae.

CONCLUSIONS

There is a positive correlation between transverse occlusal changes and positional deviations of the cervical vertebrae, especially C2 and C3.

CLINICAL RELEVANCE

The study results do not allow us to infer the clinical/functional consequences of these deviations, as well as if malocclusion's treatment would result in an improvement of intervertebral relationships.

Effects of Palatal Expansion with Torque Activation using a Transpalatal Arch: A Preliminary Single-Blind Randomized Clinical Trial

Purpose

The literature regarding the treatment of posterior crossbites using a transpalatal arch (TPA) is scarce. Moreover, there is only one clinical study on the correction of unilateral crossbites using torque activation. This is an important clinical issue; therefore, this study was conducted to show the effects of an active Goshgarian TPA in correcting nonfunctional single-tooth unilateral crossbite.

Methods

The present single-blind, randomized clinical trial examined 60 observations on 30 individuals with nonfunctional single-tooth unilateral crossbites in the first permanent molar area. Patients were randomly divided into two groups of "symmetric expansion" [control] and "expansion + torque activation" using Goshgarian TPAs [experimental]. The palatal arch was expanded at a rate of 2 mm/month, for 2-8 months. The average treatment durations were 157.9 and 117.1 days, respectively, for the control and experimental groups. Dentoskeletal alterations were assessed on dental records, posteroanterior frontal cephalographs, and occlusal radiographs taken before and after treatment. Changes induced by treatments in each group and differences between changes in both groups were analyzed statistically (α = 0.05).

Results

The treatment duration was significantly shorter in the experimental group (P < 0.05). The extent of dental displacement on the crossbite side was significant no matter what treatment was applied (P < 0.001); no between-group difference was detected (P > 0.05). Both treatments tilted the teeth in crossbite (P < 0.001) without any between-group difference (P > 0.05). The noncrossbite molar was displaced in the control group, whereas this did not occur in the experimental group (between-group P < 0.001).

Conclusions

The Goshgarian TPA can be used with torque activation in order to deliver a more effective and faster correction of nonfunctional single-tooth unilateral crossbites with more favorable clinical results.

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.

Maxillary Orthodontic Expansion Assisted by Unilateral Alveolar Corticotomy and Low-Level Laser Therapy: A Novel Approach for Correction of a Posterior Unilateral Cross-Bite in Adults

Introduction: The treatment of a true unilateral posterior crossbite often requires asymmetric maxillary expansion; however, this is challenging to achieve with conventional expansion methods because of several biomechanical limitations. In this paper, we introduce a new protocol for the treatment of a unilateral posterior crossbite in adults based on maxillary orthodontic expansion assisted by corticotomy and low-level laser therapy (LLLT) performed on the crossbite side. Methods: The study sample included 15 adults (8 females, 7 males) affected by a true unilateral posterior crossbite, with a mean age of 21.6 ± 3.1 years at the at the beginning of treatment. After the application of orthodontic appliances (palatal expander and self-ligating brackets), corticomy was performed at the buccal aspect of the crossbite side while LLLT was monthly administered up to the correction of the crossbite. The efficacy of the technique was evaluated through measurements performed on maxillary digital models. Results: All subjects reported successful correction of the posterior unilateral crossbite, and functional occlusion was achieved as well. The average expansion was greater at the crossbite side compared to the unaffected side and such difference was significant at the levels of first premolars (P < 0.05), second premolars (P < 0.05) and first molars (P < 0.05). Conclusion: Orthodontic maxillary expansion assisted by unilateral corticotomy and LLLT was effective in the treatment of the true unilateral crossbite.

Tooth-borne versus bone-borne rapid maxillary expansion for transverse maxillary deficiency: A systematic review

PURPOSE

The aim of this study was to compare dentoskeletal effects of bone-borne expanders with those of conventional expanders in adolescent and adults having transverse maxillary deficiency.

METHODS

All randomized clinical trials (RCTs) comparing the effects of bone-borne with those of tooth-borne expansion for treatment of maxillary transverse deficiency in adults and adolescents with maxillary transverse deficiency or posterior crossbite were included. The systematic search was irrespective of language and publication type. The electronic search was conducted from 1980 to January 2018.

RESULTS

The electronic searches retrieved 713 references after screening for eligibility criteria. Eight studies met the inclusion criteria for this systematic review involving 289 participants. Four studies compared rapid maxillary expansion (RME) between bone-borne and tooth-borne devices and indicated effectiveness of both devices on maxillary expansion. In the first molar region, there was no significant difference between two devices in either skeletal or dental expansion. Two studies compared the effects of bone-borne and tooth-borne device following SARME and suggested no significant difference regarding amount and pattern of expansion at various levels and in molar and premolar region between two groups. Two studies compared bone-borne and tooth-bone-borne devices.

CONCLUSION

Within the limit of the present evidence regarding maxillary expansion, it seems that both tooth-borne and bone-borne devices result in the same outcome in terms of the amount of maxillary expansion, dental tipping, stability and perceived pain both in RME and SARME procedure. PROSPERO registration: CRD42017061078.

Relations of laterality and chewing sidedness in twins

OBJECTIVES

To study, whether there are associations between chewing side preference and other lateralities, whether there is a genetic origin for preferred chewing side (PCS), relations to sex, birth order and orthodontic treatment.

MATERIALS AND METHODS

The study included 113 twin pairs, 57 pairs monozygotic, 47 pairs same sex dizygotic and 9 pairs of opposite sex. The lateralities of preferred chewing side, footedness and eyedness were assessed by functional tests and handedness was checked by asking.

RESULTS

Right-handed, -footed and -eyed as separated groups, and true-right sided (combined), were evenly distributed by preferred chewing side. By contrast, left-handed, -footed, -eyed and non-right sided used more left or both sides when chewing. Birth order affected preferred chewing side among monozygotic: the first-born twin was more likely to have the preferred chewing side on the non-right, whereas second-born twins used right side. Gender, zygosity and orthodontic treatment were not statistically significant factors.

LIMITATIONS

Examination of chewing sidedness could have been done in several different ways to provide a definite result. Sample size of opposite sex twins was very small.

CONCLUSIONS

Preferred chewing side generally seemed to follow the side where other lateralities occur; however, monozygotic twins seemed to be more receptive to it. True-right sided were more evenly distributed than non-right sided by the preferred chewing side.

Three-dimensional evaluation of surgically assisted asymmetric rapid maxillary expansion

INTRODUCTION

Unilateral posterior crossbite is classified as true unilateral posterior crossbite (TUPC) or functional posterior crossbite (FPC). The differential diagnosis between TUPC and FPC is of utmost importance for the decision of expansion protocol because conventional expansion methods have some shortcomings for TUPC. The aim of this retrospective study was to 3-dimensionally evaluate the effects of asymmetric rapid maxillary expansion combined with unilateral osteotomy.

METHODS

This study sample comprised 16 patients (mean age 18.38 ± 1.45) with TUPC. A Hyrax acrylic cap included the maxillary premolars and molars on the constricted side, and all teeth up to the central incisor were included on the other side to increase anchorage. Unilateral surgically assisted rapid maxillary expansion was performed and included anterior (aperture piriformis), lateral (zygomatic buttress), and posterior (pterygomaxillary junction) osteotomies on the constricted side and separation of the midpalatal suture. Cone-beam computed tomographic scans taken just before the operation and after 6 months of retention were used to assess skeletal, dental, and periodontal changes.

RESULTS

Expansion was seen on both sides; however, the amount of expansion and tipping was higher on the osteotomy+ side. Because the canines were not included in the acrylic cap on the osteotomy+ side, they did not present the same amount of tipping as the ipsilateral posterior teeth. More teeth were affected periodontally on the osteotomy- side; however, there were no clinically significant differences between the osteotomy+ and osteotomy- sides (mean differences range +0.54 to -0.57 mm). The aperture piriformis width increased significantly on the osteotomy+ side.

CONCLUSIONS

The treatment mechanics had no clinically detrimental effects on the supporting alveolar bone of the maxilla on either side, and it was thought to be effective in cases with TUPC; however, case selection is crucial.

Is there an asymmetry of the condylar and coronoid processes of the mandible in individuals with unilateral crossbite?

OBJECTIVES

To evaluate if there is a true skeletal asymmetry of the condylar and coronoid processes of the mandible in growing individuals with unilateral posterior crossbite (UPC) either functional or not.

MATERIALS AND METHODS

This cross-sectional study screened a total of 1120 cone beam computed tomography (CBCT) scans based on inclusion and exclusion criteria. The final sample comprised 20 CBCT images of individuals with UPC and 19 CBCT images of individuals without transverse malocclusion. The lengths of the condylar and coronoid processes were measured to evaluate asymmetry, as well as the magnitude of the mandibular lateral deviation in the UPC group.

RESULTS

There was a significant difference between the lengths of the affected and nonaffected sides of the coronoid processes in the UPC group (P < .01). The same was not observed in the condyle in the UPC group (P > .05). There were no significant differences between the groups (P > .05).

CONCLUSIONS

Although no differences in the condyle were observed, the coronoid process was asymmetric in individuals with UPC. However, this asymmetry was not considered to be clinically significant.

Improvement of masticatory kinematic parameters after correction of unilateral posterior crossbite: Reasons for functional retention

OBJECTIVE

To evaluate reverse-sequencing chewing cycles (RSCC) and their kinematic parameters on both sides before and after correction with the Function Generating Bite (FGB) appliance.

MATERIALS AND METHODS

Forty-seven patients, 8.3 ± 1.1 (mean ± SD) years of age, with unilateral posterior crossbite (35 on the right side, 12 on the left side) and 18 age-matched controls (9.1 ± 0.8 years) were selected for the study from the orthodontic division of the University of Turin, Italy. The crossbite was corrected in all patients using FGB, and mandibular motion was recorded with a kinesiograph K-7 (Myotronics, Tukwila, Wash), during chewing on both sides of a soft and a hard bolus before and after correction.

RESULTS

After correction, the percentage of RSCC significantly decreased for soft and hard (P < .001) boluses and fell within the normal range for 75% of the patients. The indices of the chewing pattern (closure angle, axis, maximum lateral excursion) significantly improved (P < .001), becoming symmetric between sides.

CONCLUSIONS

The results of this study showed that the functional appliance, FGB, was able to lower the percentage of RSCC significantly, bringing them back to the normal range in 75% of cases, and to improve the kinematic parameters that become symmetric between sides.

Occlusal traits in children with neurofibromatosis type 1

OBJECTIVES

Literature is poor of data about the occlusion in children affected by neurofibromatosis type 1 (NF1). This case-control study investigated the occlusal traits in a group of children with NF1.

SETTING AND SAMPLE POPULATION

A hundred and fifteen children with NF1 were enrolled; non-NF1 controls were sequentially selected among subjects referred to the Pediatric Dentistry Department.

MATERIAL AND METHODS

All patients underwent a clinical dental examination and a panoramic radiography. The following orthodontic variables were considered: molar relationship, overjet, overbite, cross-bite, scissor bite, and crowding/spacing.

RESULTS

Class III molar relationship resulted significantly (p = 0.01) more common in children with NF1 than in the control group as well as the unilateral posterior cross-bite (p = 0.0017). Forty-three children with NF1 (37.3%) showed radiographic abnormalities; in one case, a plexiform neurofibroma was detected.

CONCLUSIONS

An early orthodontic evaluation might be planned in the management of children with NF1 to prevent or decrease the need for extensive orthodontic interventions.

Lateral cephalometric diagnosis of asymmetry in Angle Class II subdivision compared to Class I and II

INTRODUCTION

Lateral cephalometric radiographs are traditionally required for orthodontic treatment, yet rarely used to assess asymmetries.

OBJECTIVE

The objective of the present study was to use lateral cephalometric radiographs to identify existing skeletal and dentoalveolar morphological alterations in Class II subdivision and to compare them with the existing morphology in Class I and II relationship.

MATERIAL AND METHODS

Ninety initial lateral cephalometric radiographs of male and female Brazilian children aged between 12 to 15 years old were randomly and proportionally divided into three groups: Group 1 (Class I), Group 2 (Class II) and Group 3 (Class II subdivision). Analysis of lateral cephalometric radiographs included angular measurements, horizontal linear measurements and two indexes of asymmetry that were prepared for this study.

RESULTS

In accordance with an Index of Dental Asymmetry (IDA), greater mandibular dental asymmetry was identified in Group 3. An Index of Mandibular Asymmetry (IMA) revealed less skeletal and dental mandibular asymmetry in Group 2, greater skeletal mandibular asymmetry in Group 1, and greater mandibular dental asymmetry in Group 3.

CONCLUSION

Both IDA and IMA revealed greater mandibular dental asymmetry for Group 3 in comparison to Groups 1 and 2. These results are in accordance with those found by other diagnostic methods, showing that lateral cephalometric radiography is an acceptable method to identify existing skeletal and dentoalveolar morphological alterations in malocclusions.

Asymmetric rapid maxillary expansion in true unilateral crossbite malocclusion: a prospective controlled clinical study

OBJECTIVE

To investigate the short-term effects of the asymmetric rapid maxillary (ARME) appliance on the vertical, sagittal, and transverse planes in patients with true unilateral posterior crossbite.

MATERIALS AND METHODS

Subjects were divided into two groups. The treatment group was comprised of 21 patients with unilateral posterior crossbite (mean age  =  13.3 ± 2.1 years). Members of this group were treated with the ARME appliance. The control group was comprised of 17 patients with Angle Class I who were kept under observation (mean age  =  12.3 ± 0.8 years). Lateral and frontal cephalograms were taken before the expansion (T1), immediately after expansion (T2), and at postexpansion retention (T3) in the treatment group and at preobservation (T1) and postobservation (T2) in the control group. A total of 34 measurements were assessed on cephalograms. For statistical analysis, the Wilcoxon test and analysis of covariance were used.

RESULTS

The ARME appliance produced significant increases in nasal, maxillary base, upper arch, and lower arch dimensions (P < .01) and a clockwise rotation of the occlusal plane (P  =  .001).

CONCLUSION

The ARME appliance created asymmetric increments in the transversal dimensions of the nose, maxilla, and upper arch in the short term. Asymmetric expansion therapy for subjects with unilateral maxillary deficiency may provide satisfactory outcomes in adolescents, with the exception of mandibular arch expansion. The triangular pattern of expansion caused clockwise rotation of the mandible and the occlusal plane and produced significant alterations in the vertical facial dimensions, whereas it created no displacement in maxilla in the sagittal plane.

Functional evaluation of orthopedic and orthodontic treatment in a patient with unilateral posterior crossbite and facial asymmetry

An 8-years old boy with facial asymmetry and unilateral posterior crossbite on the left side received orthopedic and orthodontic treatment. During the first phase of treatment, the narrow maxillary arch was expanded using an acrylic plate. Then, the acrylic plate was used as a bite block with occlusal indentations from the construction bite that was obtained with the incisors in a coincident dental midline. After the position of the mandible was stabilized, the second phase of orthodontic treatment was initiated using fixed appliances for detailing of the occlusion. Skeletal symmetry, ideal occlusion, and coincident dental midlines were thus achieved. Functionally, occlusal force balance and masticatory muscle activity were improved, and the chewing patterns were normalized.

Morphometric Evaluation of Craniofacial and Alveolar Arch Structures in Anencephalic Human Fetuses: A Cadaveric Study

Objective

The aim of the present study was to compare the morphometrics of the craniofacial and alveolar arch structures of anencephalic fetuses with those of normal human fetuses without anencephaly or any other anomaly.

Design

Original article.

Methods

Standard lateral and posteroanterior cephalometric radiographs of 23 anencephalic and 33 normal human fetuses aged between 21 and 40 weeks of gestation were compared. These fetuses were divided into three periods based on gestational age, and vertical, sagittal, transverse, and angular measurements were taken in the cranial base and facial regions. Moreover, intraoral measurements from the maxillary and mandibular arches were also made to determine the width and depth.

Results

N-S and S-Ba lengths and the N-S-Ba angle, measured on lateral cephalometric radiographs, were statistically smaller in anencephalic fetuses ( p < .05). The S-N-ANS, S-N-Pg, and ANS-N-Pg angles and the Go-Me length were significantly greater in anencephalic fetuses ( p < .05). Maxillary length, ramus length, and anterior facial heights were similar in both groups. On posteroanterior radiographs, all parameters except bigonial distance were found to be smaller in the anencephalic fetuses ( p < .05). Maxillary alveolar width was small among anencephalic fetuses in all three periods; whereas, the mandibular alveolar width was narrow only in the third period.

Conclusion

Cranial and facial structures were affected morphometrically to various degrees in anencephalic cases. The most significant alterations in anencephalic cases were related to measurements in the transverse direction. This indicated that cephalic tissue influenced not only the cranial base but also all facial structures.

Reverse cycle chewing before and after orthodontic-surgical correction in class III patients

OBJECTIVE

The aim of this study was to investigate the prevalence of reverse-sequence chewing cycles in skeletal class III patients before and after orthodontic-surgical therapy to evaluate whether the occlusal and skeletal correction is followed by a functional improvement.

STUDY DESIGN

Twenty skeletal class III patients (11 males and 9 females, 22.7 ± 3.0 years old) were recruited for this study. All patients received orthodontic and surgical treatment. Chewing cycles were recorded with a kinesiograph before (T0) and after (T1) therapy.

RESULTS

A significant decrease in the number of reverse chewing cycles after surgical correction was exhibited in all recordings, when chewing either soft or hard boluses, on both the right and the left side.

CONCLUSIONS

Evaluation of the prevalence of reverse chewing cycles could be considered an indicator of functional adaptation after therapy and a method for the early detection of nonresponding patients who may require further consideration using a different approach.

A possible biomechanical role of occlusal cusp-fossa contact relationships

Biomechanical features of occlusal contacts are important in understanding the role of the occlusion contributing to masticatory function. Cusp-fossa contact is the typical pattern of occlusion between upper and lower teeth. This includes static relations, such as that during clenching, and dynamic relations when mandibular teeth contact in function along the maxillary occlusal pathways, as during mastication. During clenching in the maximum intercuspal position (ICP), cuspal inclines may take the role of distributing the occlusal forces in multi-directions thus preventing excessive point pressures on the individual tooth involved. During chewing movement on the functional side, the mandible moves slightly from buccal through the maximum ICP to the contralateral side. The part of the chewing cycle where occlusal contacts occur and the pathways taken by the mandible with teeth in occlusal contacts are determined by the morphology of the teeth. The degree of contact is associated with the activity of the jaw muscles. To obtain repeatable static and dynamic occlusal contact information provided by the morphology of the teeth, maximum voluntary clenching and chewing movements with maximum range are needed. In conclusion, in addition to the standard occlusal concepts of centric relation/centric occlusion and group function/cuspid protection relation, biomechanics in static and dynamic cusp-fossa relationships should be included to develop an understanding of occlusal harmony which includes no interfering or deflective contacts in functional occlusal contact.

Condyle fossa relationship associated with functional posterior crossbite, before and after rapid maxillary expansion

OBJECTIVE

To investigate condylar symmetry and condyle fossa relationships in subjects with functional posterior crossbite comparing findings before and after rapid maxillary expansion (RME) treatment through low-dose computed tomography (CT).

MATERIALS AND METHODS

Twenty-six patients (14 girls and 12 boys, mean age 9.6 ± 1.4 years) with functional posterior crossbite (FPXB) diagnosis underwent rapid palatal expansion with a Hyrax appliance. Patients' temporomandibular joints (TMJ) underwent multislice CT scans before rapid palatal expansion (T0) and after (T1). Joint spaces were compared with those of a control sample of 13 subjects (7 girls and 5 boys, mean age 11 ± 0.6 years).

RESULTS

Anterior space (AS), superior space (SS), and posterior space (PS) joint space measurements at T0 between the FPXB side and contralateral side demonstrated no statistically significant differences. After RME treatment (T1), all three joint spaces increased on both the FPXB side and the non-crossbite side. However, differences were statistically significant only for the SS when comparing the two sides at T1. SS increased more than AS and PS in the non-crossbite condyle (0.28 mm) and FPXB condyle (0.37 mm), and PS increased only on the FPXB side (0.34 mm).

CONCLUSIONS

There were no statistically significant differences in condyle position within the glenoid fossa between the FPXB and non-crossbite side before treatment. Increases in joint spaces were observed after treatment with RME on both sides. These changes were, however, of small amounts.

Slow or rapid palatal expansion for early treatment of unilateral posterior crossbite? Evaluation of the reverse chewing cycles correction

OBJECTIVES

It is well established that patients with a unilateral posterior crossbite, when chewing on the affected side, show an increased frequency of reverse chewing cycles. It was hypothesized that the correction of reverse cycles may be due to the characteristics of the therapy. The aim was to investigate the prevalence of reverse chewing patterns in children with unilateral posterior crossbite before and after treatment with Function Generating Bite (FGB).

MATERIALS AND METHODS

Twenty children, (9 boys, 11 girls; age, mean ± SD, 7.5 ± 1.1), 10 with a right and 10 with a left posterior unilateral crossbite were selected. Mandibular movements during chewing soft and hard boluses were measured with a kinesiograph (K7 -I, Myotronics Inc. Tukwila, Washington, USA).

RESULTS

The results showed a significant difference when comparing the percentage of reverse chewing patterns, before and after therapy with FGB, during chewing on the crossbite side both with soft and hard bolus (p<0.0001). No significant differences were observed during chewing on the non-crossbite side.

DISCUSSION

The results of this study confirmed that FGB corrects both the dental and functional asymmetries. Knowing that the rapid palatal expansion does not correct the masticatory function, it is of clinical relevance, for the orthodontists, the knowledge and the understanding of the functional outcomes with different therapies.

CONCLUSIONS

The type of treatment and the biomechanics of the appliance used are of great importance for the correction of the reverse chewing cycles and for rebalancing the functional asymmetry of children with unilateral posterior crossbite.

Corticotomy-assisted orthodontic treatment: review

Corticotomy-assisted orthodontic treatment is an established and efficient orthodontic technique that has recently been studied in a number of publications. It has gradually gained popularity as an adjunct treatment option for the orthodontic treatment of adults. It involves selective alveolar decortication in the form of decortication lines and dots performed around the teeth that are to be moved. It is done to induce a state of increased tissue turnover and a transient osteopenia, which is followed by a faster rate of orthodontic tooth movement. This technique has several advantages, including faster tooth movement, shorter treatment time, safer expansion of constricted arches, enhanced post-orthodontic treatment stability and extended envelope of tooth movement. The aim of this article is to present a comprehensive review of the literature, including historical background, contemporary clinical techniques, indications, contraindications, complications and side effects.

Unilateral cross bite treated by corticotomy-assisted expansion: two case reports

BACKGROUND

True unilateral posterior crossbite in adults is a challenging malocclusion to treat. Conventional expansion methods are expected to have some shortcomings. The aim of this paper is to introduce a new technique for treating unilateral posterior crossbite in adults, namely, corticotomy-assisted expansion (CAE) applied on two adult patients: one with a true unilateral crossbite and the other with an asymmetrical bilateral crossbite, both treated via modified corticotomy techniques and fixed orthodontic appliances.

METHODS

Two cases with asymmetric maxillary constriction were treated using CAE.

RESULTS

In both cases, effective asymmetrical expansion was achieved using CAE, and functional occlusion was established as well.

CONCLUSIONS

Unilateral CAE presents an effective and reliable technique to treat true unilateral crossbite.

Muscular and condylar response to rapid maxillary expansion. Part 3: magnetic resonance assessment of condyle-disc relationship

INTRODUCTION

The aim of this prospective study was to assess temporomandibular joint (TMJ) condyle-disc positions at the sagittal and coronal planes of magnetic resonance images (MRIs) before and after rapid maxillary expansion (RME).

METHODS

The study included 18 subjects (11 girls, 7 boys) with a mean age of 12.54 years with unilateral or bilateral posterior crossbite that included at least 3 posterior teeth. The clinical and radiographic assessments of the TMJ were done before (T1) and 18 weeks after (T2) RME. A Haas-type expansion appliance was used for an average treatment time of 3.5 weeks.

RESULTS

A visual MRI analysis of pretreatment condyle-disc positions showed that 8 TMJs had medial disc displacement, 3 had anteromedial disc displacement, and 2 had lateral disc displacement. The disc positions remained unchanged at T2 except in 1 subject, who developed unilateral anterior disc displacement. Unilateral joint sounds developed in 3 subjects without changes in the disc positions.

CONCLUSIONS

Posterior crossbite can be considered a minor risk factor for temporomandibular disorder (TMD). RME is neither a risk factor nor a prevention for TMD. Coronal MRIs contribute complementary information for optimal diagnosis of TMD.

Malocclusion as a risk factor in the etiology of headaches in children and adolescents

INTRODUCTION

The purpose of this study was to determine the importance of occlusal factors in recurrent headaches in children and adolescents without other signs or symptoms of temporomandibular disorders or related craniomandibular disorders.

METHODS

A sample of 50 children and adolescents, ages 8 to 16, who reported headaches was obtained from the University at Buffalo Orthodontic Clinic records; a control group of 50 children and adolescents, matched for age and sex, was also obtained. Plaster models, made during the routine collection of orthodontic records, were used to obtain the following occlusal trait measurements: Angle classification, overjet, anterior and posterior crossbite, scissors-bite, overbite, open bite, dental midline discrepancy, crowding, spacing, and dental development stage.

RESULTS

Overbite, overjet, and posterior crossbite showed statistically significant associations (chi-square) with increased risk for headaches. Logistic regression analysis demonstrated that overjet was a significant factor only because of its correlation with overbite and posterior crossbite. Overjet was not significant after adjusting for the other 2 variables, whereas overbite and posterior crossbite were associated with significantly increased risk (>3:1) of headache. The combination of 2 or more of these 3 occlusal factors increased the risk of headache even more (8.5:1).

CONCLUSIONS

Posterior crossbite and overbite > or =5 mm were associated with significantly increased risk of headache in children and adolescents.

Análise da mastigação em indivíduos que apresentam mordida cruzada unilateral na faixa-etária de 07 a 12 anos

OBJETIVO: analisar a função de mastigação relacionada à mordida cruzada posterior unilateral em crianças na faixa etária de sete a doze anos. MÉTODOS: dez indivíduos de ambos os sexos com mordida cruzada unilateral posterior sem intervenção ortodôntica. Na avaliação fonoaudiológica os itens considerados foram: corte do alimento, lado da mastigação, ritmo, postura labial, escape de alimentos, movimento de mandíbula, participação exagerada da musculatura perioral, acúmulo de alimento no vestíbulo da boca, posição e tamanho do bolo alimentar. RESULTADOS: dos dez indivíduos avaliados, 80% apresentaram mastigação unilateral do mesmo lado da mordida cruzada posterior unilateral e 20% mastigação bilateral. Dos oito indivíduos analisados com mastigação unilateral, os resultados encontrados foram: corte anterior, sem escape de alimentos e movimentos rotatórios 100%; ritmo lento 50% e rápido 50%; lábios fechados 75%; participação exagerada da musculatura perioral 62,5%; sem acúmulo de alimentos 87,5%; bolo alimentar centralizado 75%; tamanho do bolo pequeno 62,5%. CONCLUSÃO: dos casos avaliados, observou-se que 80% confirmam a relação entre mastigação unilateral e mordida cruzada posterior unilateral. Na mastigação, não foram evidenciadas quaisquer outras alterações que possam estar relacionadas à mordida cruzada posterior unilateral e mastigação unilateral.

Chewing cycle kinematics of subjects with deepbite malocclusion

INTRODUCTION

The notion that chewing cycle shape and cycle dynamics differ between subjects with and without malocclusion is largely based on qualitative studies that combined various types of malocclusion. The purpose of this prospective study was to determine whether chewing cycle kinematics of untreated young adults with deepbite malocclusion differ from those with normal occlusion.

METHODS

Twenty-three deepbite subjects (>50% overbite) and 24 controls with normal occlusion chewed gum (right side only) while their jaw movements were recorded at 100 Hz by using an optoelectric jaw tracking system.

RESULTS

Differences in cycle duration between deepbite and control subjects were small and not significant (P >.05). The deepbite subjects showed significantly (P <.05) less maximum inferior excursion (7.7 vs 9.0 mm) and significantly greater maximum posterior excursion (5.1 vs 4.0 mm) than subjects with normal occlusion. In addition, the deepbite subjects had significantly smaller maximum vertical velocities than subjects with normal occlusion (49.2 vs 60.8 mm per second). Deepbite subjects also showed significantly (P <.05) less cycle-to-cycle variability in maximum velocities and excursions to the balancing side but significantly (P <.05) greater variability in cycle duration and maximum posterior excursions.

CONCLUSIONS

A deepbite malocclusion alters the shape of chewing cycles and the consistency of chewing cycle kinematics.

Unilateral posterior crossbite and mastication

OBJECTIVE

This study was designed to characterize masticatory-cycle morphology, and distance of the contact glide in the closing masticatory stroke, in adult subjects with uncorrected unilateral posterior crossbite (UPXB), comparing the results obtained with those obtained in a parallel group of normal subjects.

STUDY DESIGN

Mandibular movements (masticatory movements and laterality movements with dental contact) were registered using a gnathograph (MK-6I Diagnostic System) during unilateral chewing of a piece of gum. Traces were recorded on the crossbite and non-crossbite sides in the crossbite group, and likewise on both sides in the non-crossbite group.

RESULTS

Mean contact glide distance on the crossbite side in the UPXB group was significantly lower than in the control group (p<0.001), and mean contact glide distance on the non-crossbite side in the UPXB group was significantly lower than in the control group (p=0.042). Cycle morphology was abnormal during chewing on the crossbite side, with the frequency distribution of cycle types differing significantly from that for the noncrossbite side and that for the control group (p<0.001).

CONCLUSIONS

Patients with crossbite showed alterations in both contact glide distances and masticatory cycle morphology. These alterations are probably adaptive responses allowing maintenance of adequate masticatory function despite the crossbite.

Changes in the masticatory cycle after treatment of posterior crossbite in children aged 4 to 5 years

INTRODUCTION

The aim of this study was to analyze the dynamics of the masticatory cycle after occlusal adjustment through coronoplasty on deciduous teeth (selective grinding) and composite resin occlusal guidance for posterior crossbite correction.

METHODS

Nineteen children, aged 4 to 5 years, with functional posterior crossbites diagnosed at their clinical examinations, were selected. Analyses of masticatory cycles, including lateral excursive movements, were performed before and after treatment by using kinesiographic examinations in the 3 reference planes (frontal, horizontal, and sagittal). The examinations were done during bubble-gum chewing. The data were submitted to sign, Mann-Whitney, and paired t tests concerning the variables: left maximum lateral movement, right maximum lateral movement, total lateral movement (LM), vertical movement (VM), anteroposterior maximum movement, maximum lateral movement (MLM), and total maximum lateral movement (TMLM).

RESULTS

The treatment produced increased TMLM, a significant increase of the MLM opposite the crossbite, no statistically significant difference of the crossbite side, and a significant decrease of LM. Left crossbite children showed significant decreases in the LM after treatment; right crossbite children showed significant increases in VM after treatment.

CONCLUSIONS

Functional crossbite treatment with selective adjustment and occlusal guiding changed masticatory cycle patterns, producing larger horizontal and vertical planes. The cycles became more symmetric in the frontal plane, increasing the tendency of bilateral alternate mastication.

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.

Occlusal patterns in patients with idiopathic scoliosis

INTRODUCTION

Idiopathic scoliosis is an orthopedic condition characterized by faulty posture. It might also be associated with some mild forms of facial asymmetry or dental deviations. The aim of the study was to clinically examine the occlusions of patients with idiopathic scoliosis.

METHODS

Ninety-six consecutive orthopedic patients with idiopathic scoliosis were examined. The orthopedic data of this group were recorded from their hospital files. The occlusal features of a random group of 705 Ashkenazi children served as the control. Frequency distributions were compared with the chi-square test.

RESULTS

The distribution of the Angle classes of malocclusion was significantly different in the 2 groups (P = .0001) because of many Class II subdivision patients in the orthopedic group. Other evidence of asymmetrical malocclusion was found in upper (P =.002) and lower midline deviations (P =.0001), and a higher frequency of anterior (P = .024) and posterior (P =.020) crossbites. In the experimental group, no association was found between site, side, or severity of scoliosis and the appearance or site of the malocclusion features examined.

CONCLUSIONS

Patients with idiopathic scoliosis have asymmetric features of malocclusion compared with a random population.

Reverse-sequencing chewing patterns before and after treatment of children with a unilateral posterior crossbite

The aim of this study was to compare the percentage of reverse-sequencing chewing cycles in 22 children [9 boys and 13 girls; mean age +/- SD, 8.6 +/- 1.3 and 8.8 +/- 1.5 years, respectively), with a unilateral right or left posterior crossbite, before and after therapy. The chewing cycles were recorded using a kinesiograph while the subjects masticated a soft and a hard bolus on both the crossbite and non-crossbite side. Chewing data were acquired before and 6 months after orthodontic treatment of the crossbite with an orthodontic functional appliance, the 'Function Generating Bite'. The results showed that, before therapy, the percentage of reverse-sequencing chewing cycles on the crossbite side was significantly higher than that on the normal side (P < 0.001) with both the soft and hard bolus. In addition, the percentage of reverse-sequencing chewing cycles on the crossbite side before therapy was significantly greater than after therapy with both a soft and hard bolus (P < 0.001). No significant differences were found in the percentage of reverse-sequencing chewing cycles on the non-crossbite side, before or after therapy, either with a soft or hard bolus.

Movement of the lateral and medial poles of the working condyle during mastication in patients with unilateral posterior crossbite

Patients with unilateral posterior crossbite often show reverse sequential jaw movement patterns on the frontal view during mastication on the crossbite side. Recent studies show that such patients are prone to suffer from temporomandibular joint (TMJ) disc displacement, particularly the lateral portion. The purpose of this study was to examine the movement of the lateral and medial poles of the working condyle during mastication in such patients. Subjects were 12 consecutive patients with unilateral posterior crossbites and without TMJ disc displacements and 12 normal subjects. An optoelectronic jaw-tracking system with 6 degrees of freedom was used to record the motion of the lateral and medial poles of the working condyle during mastication of standardized hard, gummy jelly. The data from the first 10 cycles were analyzed. The lateral and medial poles of the condyle on the crossbite side moved more in the medial direction and less in the lateral direction during mastication in the crossbite patients than the condyle in the normal subjects. The lateral pole of the working condyle moved more in the posterior and inferior directions and less in the anterior direction than the medial pole in all subjects. These results suggest that these condylar movements in patients with unilateral posterior crossbites might be related to the susceptibility to TMJ disc displacement, particularly the lateral portion.

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.

Improvement in jaw motion following treatment of unilateral crossbite in a child with primary dentition: a case report

This case report examines jaw motion during both habitual opening-closing and gum chewing in a young (3 years, 10 months) patient with unilateral crossbite at the primary dentition stage. Jaw motion was measured three times: 1. before treatment; 2. after active treatment; and 3. after retention. The abnormal habitual open-close pathway seen prior to treatment was improved after retention. Prior to treatment, movement of the affected-side condyle preceded movement of the non-affected-side condyle during opening. After retention, the movement of the condyles was better coordinated. The chopping type chewing pattern, with less lateral movement, before treatment changed to a more grinding type pattern on the affected side after activation. This study suggests that the prescribed treatment effectively improved both the patient's morphology and function. However, neither the open-close pathways nor the chewing patterns were completely normal after retention. The results in this case suggest that early treatment of functional unilateral crossbite can be effective.