Unilateral Posterior Crossbite Research Articles

CBCT evaluation of condylar changes in children with unilateral posterior crossbites and a functional shift

Posterior crossbite is one of the most frequently occurring malocclusions in adolescents with a prevalence of 7% to 23%. The most common form of posterior crossbite is a unilateral posterior crossbite with a functional side shift. It has been suggested that functional posterior crossbites (FUPXB) may result in right-to-left-side differences in the condyle fossa relationship, resulting in temporomandibular joint (TMJ) problems. The objective of this study was to determine if pathological position of the condyles can cause condylar signs or symptoms like degenerative joint disease (DJD) or juvenile condylar resorption (JCR), or if the position of the condyle is just an altered position within the TMJ. Sixty patients with an average age of 9.6years were randomly selected from the office of one of the investigators (T.S.). The study group consisted of 29 patients with a FUPXB and the control group had 31 patients with no posterior crossbite. All patients had multislice CT scans of the TMJ taken as part of the orthodontic records. Transverse widths were measured at the skeletal base and the dentoalveolar base. Molar inclinations, condylar angulations, condylar anterior joint space, superior joint space, and posterior joint space were measured. Independent sample t-tests were used to compare different measurements between groups and paired sample t-tests were used to compare differences within the same patient. Reliability of measurements were determined using pairwise correlation. For dentoalveolar measurements of transverse width, the maxillomandibular difference for the study group was -8.2 mm and for the control group was -4.0 mm. No significant differences were found between the molar inclinations, condylar width, angulation, or any joint space measurements between the two groups. A total of 61.3% of the subjects in the control group and 72.4% in the study group had a radiographic sign of joint disease. The lack of condylar positional differences between the control and crossbite groups suggests that TMJ signs and symptoms in the study group may be related to remodeling in the TMJ instead.

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

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. 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. 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). 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.

A new method for the treatment of unilateral posterior cross-bite: a three-dimensional finite element stress analysis study

BackgroundStress relieving corticoto mies during the treatment of maxillary expansion are needed in adult patients.MethodsThree-dimensional (3D) finite element model was prepared, and finite element analysis was processed to evaluate the stress distributions within the skull and maxillary teeth during surgically assisted rapid maxillary expansion (SARME) treatment.ResultsExpansion forces generated more stress on the corticotomy-applied part of the maxilla. The stress levels decreased dramatically above the corticotomy line.ConclusionAsymmetric transveral maxillary expansion might be achieved from a symmetric force generating screw during SARME treatment. SARME osteotomies may concentrate the stress in the expanding maxilla and reduce the pain in other parts of the cranium.

Erratum to: Evaluation of masticatory muscle activity in patients with unilateral posterior crossbite before and after rapid maxillary expansion.

Erratum to: Evaluation of masticatory muscle activity in patients with unilateral posterior crossbite before and after rapid maxillary expansion.

Oral health-related quality of life among children with excessive overjet or unilateral posterior crossbite with functional shift compared to children with no or mild orthodontic treatment need.

To compare Oral health-related quality of life (OHRQoL) among 9-year-old children with excessive overjet (EO) to children with unilateral posterior crossbite (UPC) and children with normal occlusion (NO). The study sample sourced from 19 Public Dental Service Clinics in Sweden. Reported are baseline data originating from two controlled trials, one regarding UPC and the other focusing on EO. The NO children derive from the same trials. The UPC group comprised 93 children (45 boys and 48 girls), the EO group 71 children (36 boys and 35 girls), and the NO group 65 children (32 boys and 33 girls). In conjunction to a clinical examination, all children completed the Child Perceptions Questionnaire (CPQ8-10) for evaluation of OHRQoL. The CPQ8-10 comprises 25 questions grouped into four domains: oral symptoms, functional limitations, emotional, and social well-being. Validated questions about pain in the jaws and face were also included. The total mean CPQ score was 5.1 for the UPC, 7.4 for the EO, and 4.4 for the NO group, showing a significant difference between the UPC and EO (P = 0.048) and between EO and NO group (P = 0.012). These differences remained when adjusted for the confounders' caries, trauma, enamel defects, and headache. No difference between UPC and NO was found. The EO children also reported significantly higher scores in the domains emotional and social well-being (P = 0.039 and P = 0.012). The study would be strengthened if a longitudinal design had been performed. Children with EO reported significantly lower OHRQoL compared to children with UPC or NO. The children generally reported low CPQ scores that imply an overall fairly good OHRQoL.

Evaluation of masticatory muscle activity in patients with unilateral posterior crossbite before and after rapid maxillary expansion.

The relationship between unilateral posterior crossbite (UPCB) and the possible asymmetric activation of the jaw muscles in children is still under debate. This study aimed at evaluating the jaw muscle activity of children with UPCB before and after rapid maxillary expansion (RME) by means of surface electromyography and a standardized sampling protocol. Twenty-nine children with UPCB (UPCB-group, mean age 9.6 ± 1.6 years) and 40 UPCB-free controls (Control-group, 10.5 ± 1.1) were recruited. The activity of the left and right anterior temporalis (AT) and superficial masseter muscles (MM) was recorded during maximum voluntary clenching and a chewing task (T0). In the UPCB-group, data were collected, also, after the correction of the UPCB with RME (T1) and 6 months later (T2), without any further treatment. Electromyographic indices comparing the activity of paired muscle were computed via software to estimate the extent of asymmetric AT and MM activity. Paired and unpaired t-test or Wilcoxon-signed rank and Mann-Whitney U test, ANOVA or Friedman test and chi-squared test were used in the statistical analysis. Both groups presented with asymmetric activity of the muscles, which did not differ between groups (T0, all P > 0.05). The treatment determined a decrease in muscular activity (T1, P = 0.040), and a more asymmetric pattern of muscle activation during chewing (T1, P = 0.040), which returned similar to baseline values at T2 (all P > 0.05). UPCB does not contribute to an asymmetric activation of AT and MM during functional tasks. The treatment of UPCB by RME did not determine a more symmetric activity of the assessed muscles.

Dimensional changes in the palate associated with slow maxillary expansion for early treatment of posterior crossbite.

To compare palatal symmetry, dimensions, and molar angulations following early mixed-dentition slow maxillary expansion with parameters in normal controls. A total of 30 patients treated with a Haas-type expander for unilateral posterior crossbite with functional shift were compared with 30 controls matched for dental age, gender, and molar relationship. Records were taken before (T1) and after expansion (T2). Palatal width, surface area, volume, and molar angulations were measured on digitized models. Surface area and volume were split in half then divided into anterior, middle, and posterior segments to measure symmetry. Student's t-test was used to assess group differences. Mean intercanine width increased 4.65 mm, and intermolar width increased 4.76 mm. The treated mean surface area increased 127.05 mm2 compared with 10.35 mm2 in controls. The treated palatal volume increased 927.55 mm3 compared with 159.89 mm3 for controls. At T1, the controls showed significant differences in surface area and volume between the anterior palatal segments. At T2, this difference occurred in surface area of middle palatal segments of the treated sample. First permanent molars showed an increased buccal and distal inclination after treatment, opposite to controls. The increase in buccal inclination was greater on the crossbite side. The Haas-type expander results in similar expansion across the canines and first molars. A palate that is symmetrical before expansion may become asymmetric after expansion but only in the middle segment. Changes in individual molar angulation following palatal expansion can be measured without radiation imaging.

Compensations in Bone Morphology and the Dentition in Patients With Untreated Unilateral Cleft Lip and Palate: A Cone-Beam Computed Tomographic Analysis.

The purpose of this study was to quantitatively assess dentoalveolar and skeletal compensations in patients with untreated unilateral cleft lip and palate (UCLP). We hypothesized that there are significant skeletal and dental adaptations in UCLP cases compared to a comparison maxillary crossbite group. A convenience retrospective sample of 30 patients with UCLP and a comparison group of 30 patients with unilateral posterior crossbite without CLP. Cone-beam computed tomography scans (CBCTs) were used to evaluate dental and skeletal compensations. In addition, alveolar bone thickness was measured at 2-mm increments in mesiodistal and faciolingual cross-sectional views along the long axis of the central incisors. Alveolar bone height was measured, and the percentage of root length supported by bone was calculated. Compensations for unilateral cleft lip and palate were restricted to the cleft site and adjacent structures. Dental compensations include alteration in the position of cleft-adjacent maxillary incisors and maxillary canines. No gross skeletal compensations were found. Alveolar support of cleft adjacent incisors was similar to controls except for measurements in the most coronal and apical regions. The cleft group contralateral incisors exhibited buttressing effects and had significantly higher alveolar thickness in the coronal half of the tooth. There was less (5%) alveolar coverage of the cleft-facing aspect of the central incisor root than all other incisors. The bone adaptation to the presence of a cleft was localized in the vicinity of the cleft, and adaptations in the mandible were not apparent.

Gait and posture analysis in patients with maxillary transverse discrepancy, before and after RPE

The purpose of this study was to evaluate the effects of the rapid palatal expansion (RPE) on posture and gait analysis in subjects with maxillary transverse discrepancies. Forty-one patients between 6 and 12 years were divided into 3 groups: 10 control subjects (Cs), 16 patients with unilateral posterior crossbite (CbMono), 15 patients with maxillary transverse discrepancy and no crossbite (Nocb). Every subject underwent gait analysis and posturographic examination in order to evaluate the presence of balance alterations before (T0) and after (T4) RPE application. The examinations were performed through a six-cameras stereophotogrammetric system (60-120Hz, BTS S.p.A.) synchronized with two force plates (FP4060, Bertec Corp.). Romberg test was performed on a force plate, and the statokinesiogram and joint kinematics were evaluated. One-way Anova was performed among the variables after evidence of normal distribution (Levene's test for equality of variances) and Kruskal-Wallis test (P<0.05), in order to compare the three groups of subjects. While paired t-test was performed, or Kruskal-Wallis test, instead when comparing pre- and post-RPE application within the same group of subjects (P<0.05). Tamane T2 or Bonferroni correction was applied where needed. The posturographic analysis reveal significant differences across the 3 population: 95% power frequency in medio-lateral and antero-posterior direction in T0, median frequency in medio-lateral direction in T0, mean power frequency in medio-lateral direction in T0. Significant differences were also registered in the three-dimensional joints kinematics variables, mainly between Cs and Cbmono in T0 and T4 and between Cbmono and Nocb in T4. A detectable correlation between dental occlusion and body posture is shown in this study that confirms another benefit of the RPE. This was mainly revealed in the dynamic posture where modifications at the mandibular level affect the whole body.

The electrical activity of the masticatory muscles in children with cleft lip and palate.

Information regarding masticatory muscle function in children with cleft lip and palate (CLP) is limited. As a consequence, research on masticatory muscle activity in cleft subjects is needed. To assess masticatory muscle activity in children surgically treated for CLP as well as identify the possible factors associated with this activity. The sample comprised 82 children with mixed dentition and Class I occlusions (25 children with unilateral CLP and 57 subjects with no cleft abnormalities). A DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) was used to take electromyographical (EMG) recordings of the temporal and masseter muscles both in the mandibular rest position and during maximum voluntary contraction (MVC). Patients with clefts showed a significant increase in temporal muscle activity at rest compared with the controls. The presence of clefts and unilateral posterior crossbites are factors strongly associated with increased temporal muscle EMG potentials during rest position. Children with clefts have altered temporal muscle function. The presence of posterior crossbites affects the temporal muscle activity in cleft subjects. Early diagnosis and orthodontic treatment of malocclusions are necessary to achieve functional improvement in these patients.

Early approach of the transversal malocclusions, diagnosis and treatment. Literature review

Summary: The issue of transversal malocclusions has been widely studied bymany authors around the world and researched from many perspectives: skeletal, muscular, dental andfunctional. Reports describe the different etiologies, complications and compromises ofmalocclusion, leading to a general consensus that, the sooner it is corrected, the less theirconsequences and negative effects on growth and development will be, and good results can beachieved with great long-term stability. Therefore the aim of this paper is to identify through aliterature review, the necessary tools that allow the detection, diagnosis and treatment of thesemalocclusions at an early stage and to prevent severe skeletal asymmetries. Key words: Transversalmalocclusions. Cross-bite. Unilateral posterior crossbite. Bilateral posterior. Crossbite. Planasdirect tracks. Early transverse treatment.

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

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. 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. 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. 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 Features and Caries Experience of Hong Kong Chinese Preschool Children: A Cross-Sectional Study.

Objective: To study occlusal features and their relation to caries experience in Hong Kong Chinese preschool children. Methods: Seven kindergarten classes in Hong Kong were selected using a stratified random sampling method, and the 4- and 5-year-old Chinese kindergarten children were invited to join the survey. Two calibrated dentists performed the clinical examinations in the kindergartens. Occlusion features, including incisal overjet; canine and molar relationship; median diastema; and primate space as well as malocclusion features, including crossbite; anterior open bite; and scissor bite, were recorded. Caries experience was recorded with the dmft index. Results: A total of 538 children were invited to participate in the study, and finally 495 children were examined (92%). Approximately half (52%) had a normal incisor relationship. Most children had a class I canine relationship (left-79%; right-75%). Approximately two-thirds had a flush terminal plane (left-64%; right-65%). Most children (76%) had a maxillary primate space, and 47% had a mandibular primate space. The prevalence of median diastema, anterior crossbite, and unilateral posterior crossbite was 30%, 12% and 1%, respectively. No bilateral posterior crossbite or scissor bite was found. Approximately half (49%) had caries experience. The mean dmft score was 2.1. Gender and age were not associated with either the studied occlusal features or the mean dmft score (p > 0.05). Conclusion: Approximately half of the Hong Kong preschool children studied had a normal occlusion, and two-thirds of them had a flush terminal plane. About three-quarters of them had a maxillary primate space, and half of them had a mandibular primate space. Their occlusal traits were not associated with caries experience and prevalence.

Orthosurgical Management of a Skeletal Class III in an Operated Cleft Lip and Palate Case

A 16-year-old female with an operated unilateral cleft lip and palate reported with a chief complaint of severely crowded upper and lower teeth. Significant orthodontic clinical features were retropositioned maxilla, a reverse overjet and a unilateral posterior crossbite, retruded upper lips, and a deranged occlusion. Comprehensive orthodontic therapy including arch expansion with nickel titanium palatal expander followed by a LeFort I maxillary advancement was carried out. The treatment over a period of 3 years resulted in a 97% improvement of the peer assessment review index and long-term stability.

The influence of crossbite in early development of mandibular bone asymmetries in paediatric patients.

BackgroundAll authors agree that posterior crossbite is a malocclusion that affects mandibular growth and may lead to skeletal asymmetry but there are few data on which age these modifications are easily quantifiable.Material and MethodsFor this study, the researchers used x-ray records of 217 children between 6 and 9 years of age, in the mixed dentition stage and with unilateral posterior crossbite. All the horizontal variables were traced and evaluated by the principal researcher, using the tpsDig version 2 computer program. Subsequently, a descriptive and statistical analysis was carried out, using the SPSS 17.0 for Windows program.Results and DiscussionAfter analysing the vertical mandibular traces on the x-rays, the researchers found, in all cases, quantifiable differences between the crossbite side and the non-crossbite side. The differences between horizontal variables were statistically significant (p<0.005) for the entire sample (H3-H4), in the group of boys (H3-H4) and in the 7-year old age group (H1-H2 and H3-H4). Differences were observed in the size of the horizontal measures between the crossbite side and the non-crossbite side. Some of these differences were significant as a function of the sex and age of the study sample. Key words:Crossbite, Mandibular asymmetry, Panoramic.

Early interception of mandibular shifting: A longitudinal approach from deciduous through mixed and permanent dentitions

AbstractA Class II malocclusion with a unilateral posterior crossbite in the late deciduous dentition is a challenging type of malocclusion to intercept. The objective is to analyze the long-term changes in a patient with a skeletal Class II division 1 malocclusion. A 5-year-old female child who was referred from a pediatric dentist came for consultation. Correction of posterior crossbite involves expansion of the maxillary arch with the aim of removal of occlusal interferences and elimination of the functional shift of the mandible. The treatment comprised three stages: (1) Expansion of the maxillary arch was performed with a modified Haas palatal expander and the clinical procedures thus resulted in improved facial symmetry and satisfactory functional occlusion in the mixed dentition (8 years 10 months). (2) Distalization of maxillary first molars was done with a Kloehn type headgear and a lip bumper was placed in the mandible to maintain the arch perimeter (12 years). (3) A 0.022 inch × 0.028 inch standard edgewise fixed appliance was used for comprehensive orthodontic treatment and the objectives were accomplished (14 years 5 months). The results showed great improvements in function and esthetics, and posttreatment stability was good after 7 years and 5 months.

Asymmetric molars' mesial rotation and mesialization in unilateral functional posterior crossbite and implications for interceptive treatment in the mixed dentition.

Symmetric transverse expansion is the main outcome of the early treatment in subjects with unilateral functional posterior crossbite. The aim of this study was to analyse mesial rotation and mesialization of upper first molars as sagittal parameters to be corrected in the treatment of these patients during the mixed dentition. Digital dental cast measurements (rotation and mesialization) were performed in a sample of 48 subjects with unilateral posterior crossbite (UPXB; 19 males and 29 females, mean age 10.2 ± 1.2 years) and in a control group of 35 subjects with normal Class I occlusion (17 males and 18 females, mean age 9.9 ± 1.3 years). An independent sample t-test, the Mann-Whitney test, Fisher's exact test, and Pearson correlation were used for statistical comparison. The amount of upper molar rotation was significantly greater in the experimental group when compared with the control group. A clinically significant 'upper molar rotation' (UMR) was present in 66.7 per cent of the subjects with UPXB versus 5.7 per cent of the control group. The UMR group presented also a significant mesialization of upper first molars when compared with the control group. In the experimental group, there was a significant difference between rotation and mesialization in the right and left side and a correlation has been found between these two variables and the amount of Class II molar relationship at the crossbite side. This is an epidemiological case-control study and the discussed effects of an early correction of the asymmetric upper molars' migration are only speculations based on an association relationship. The findings of this study show an asymmetric upper first molars' migration (rotation and mesialization) in unilateral functional posterior crossbite versus a control group. An early evaluation and correction of the molars' migration during the mixed dentition should be considered in order to obtain a correct inter-occlusal sagittal molar relationship, space for an adequate eruption of permanent teeth, and perhaps reduce the need of a following fixed appliance treatment in the permanent dentition.

Morphofunctional compensation of masseter muscles in unilateral posterior crossbite patients.

Unilateral posterior crossbite is a widespread, asymmetric malocclusion characterized by an inverse relationship of the upper and lower buccal dental cusps, in the molar and premolar regions, on one side only of the dental arch. Patients with unilateral posterior crossbite exhibit an altered chewing cycles and the crossbite side masseter results to be less active with respect to the contralateral one. Few studies about morphological features of masticatory muscle in malocclusion disorders exist and most of these have been performed on animal models. The aim of the present study was to evaluate morphological and protein expression characteristics of masseter muscles in patients affected by unilateral posterior crossbite, by histological and immunofluorescence techniques. We have used antibody against PAX-7, marker of satellite cells, and against α-, β-, γ-, δ-, ε- and ζ-sarcoglycans which are transmembrane glycoproteins involved in sarcolemma stabilization. By statistical analysis we have evaluated differences in amount of myonucley between contralateral and ipsilateral side. Results have shown: i) altered fibers morphology and atrophy of ipsilateral muscle if compared to the contralateral one; ii) higher number of myonuclei and PAX-7 positive cells in contralateral side than ipsilateral one; iii) higher pattern of fluorescence for all tested sarcoglycans in contralateral side than ipsilateral one. Results show that in unilateral posterior crossbite hypertrophic response of contralateral masseter and atrophic events in ipsilateral masseter take place; by that, in unilateral posterior crossbite malocclusion masticatory muscles modify their morphology depending on the function. That could be relevant in understanding and healing of malocclusion disorders; in fact, the altered balance about structure and function between ipsilateral and contralateral muscles could, long-term, lead and/ or worsen skeletal asymmetries.

Long-term changes of alveolar buccal bone after rapid maxillary expansion in an adolescent patient

Besides the orthopedic effect of midpalatal suture split, rapid maxillary expansion causes buccal movement of supporting teeth by tipping and bodily translation. The orthodontic effect leads to periodontal changes such as reduction of buccal alveolar bone plate thickness and buccal alveolar crest level. The question that remains is whether any long-term bone regeneration occurs in the buccal bone plate after expansion. This report describes the longitudinal changes in the alveolar crest level of the maxillary posterior teeth after rapid maxillary expansion (RME) in an 11-year-old patient. This patient was included in a sample of a previous publication and initially presented with a unilateral posterior crossbite on the left side in her permanent dentition. After the RME procedure with use of a tooth-tissue-borne Haas-type expander, the patient experienced extensive buccal bone dehiscences in the supporting teeth. After expansion, she underwent comprehensive orthodontic treatment. Approximately 8 years after the expansion, orthodontic follow-up showed that the orthodontic outcomes, including the posterior crossbite correction, remained stable. The patient then underwent cone beam computed tomography (CBCT) for extraction of her third molars. Buccal bone dehiscences remained in the first maxillary premolars and in the mesial roots of the maxillary first molars. Also, gingival recession was observed in many maxillary and mandibular teeth. This case report suggests that alveolar bone dehiscence that develops immediately after RME tends to remain in the long term and predispose gingival recession. Factors related to this variable longitudinal behavior should be elucidated by future studies.

Correction of transverse maxillary deficiency and anterior open bite in an adult Class III skeletal patient

Transverse maxillary deficiency may be associated with sagittal or vertical problems of the maxilla or mandible. It may contribute to unilateral or bilateral posterior crossbite, anterior dental crowding, and unesthetic black buccal corridors on smiling. An adequate transverse dimension is important for stable and proper functional occlusion. Surgically, assisted rapid palatal expansion has been the treatment of choice to resolve posterior crossbite in skeletally mature patients. The following case report presents an adult Class III skeletal patient with an anterior open bite and bilateral posterior crossbite which was treated by surgically assisted rapid maxillary expansion with satisfactory outcomes.