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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.

Objective: To evaluate the expression of an activator of nuclear factor-kappa (RANK), osteoprotegerin (OPG), osteopontin (OPN), and transforming growth factor ß1 (TGF-ß1) in gingival crevicular fluid (GCF) of teeth subjected to orthodontic forces. Materials and Methods: A randomized, pilot clinical trial including 10 healthy volunteers was conducted using a split-mouth design. Orthodontic elastic separators were placed between the second premolar and first molar, with the contralateral quadrant serving as a control. The GCF samples were collected from the tension and compression sites at baseline, 24 hours, and 7 days after the placement of separators. The GCF sample volumes were measured using a Periotron 8000, and total protein concentrations were determined. Levels of RANK, OPG, OPN, and TGF-ß1 were also analyzed using a multiplex enzyme-linked immunosorbent assay. Results: The control sites remained unchanged throughout the study. In contrast, the concentration of OPG significantly decreased at the compression site by 24 hours, and the amount and concentration of RANK differed significantly between the control, compression, and tension sites after 7 days. A significant increase in absolute TGF-ß1 levels was also detected at the compression site versus the control and tension sites after 7 days. Conclusion: Bone metabolism is affected by application of force to the teeth by elastic separators. Both increased expression of bone resorptive mediators (eg, RANK and TGF-ß1) and decreased expression of a bone-forming mediator (eg, OPG) on the compression side were detected.

Objectives: This study aimed at clarifying the morphological interactions among the cranial base, face, and mandible, to improve the assessment and treatment of skeletal malocclusions involving the mandible. Design Untreated adult subjects (n = 187) were grouped according to standard cephalometric criteria of vertical and sagittal relationships. Geometric morphometrics were used to test the null hypothesis that integration patterns between the mandible and its associated basicranial and upper midfacial counterparts would be similar among various vertical and sagittal facial patterns. Results: The null hypothesis was rejected for vertical groups, because the dolicho- and brachyfacial subjects showed significantly different integration patterns, but was accepted for sagittal groups, which showed identical covariation patterns. The morphological integration between the cranium-face and mandible were similarly high in the three skeletal classes, which explained the similarly large covariance between the two structures (57.80% in Class II to 60% in Class III). Conclusions: Dolicho- and brachi-facial subjects showed specific and different cranium-face and associated mandible configurations. The cranium-face configuration may have an important influence (∼60%) on the generation of sagittal (anteroposterior) skeletal malocclusions. The remaining morphological component of the skeletal malocclusion (∼40%) would be independent of this particular integration (PLS1) between the cranium-face and mandible. © 2013 Elsevier Ltd., This research was founded by the Spanish Ministry of Economy and Competitiveness (Projects CGL2012-36682 and CGL2012-37279).

The aim of this study was to determine the relationship between the closure stage of the spheno-occipital synchondrosis and the maturational stage of the cervical vertebrae (CVM) in growing and young adult subjects using cone beam computed tomography (CBCT). CBCT images with an extended field of view obtained from 315 participants (148 females and 167 males; mean age 15.6 ±7.3 years; range 6 to 23 years) were analyzed. The fusion status of the synchondrosis was determined using a five-stage scoring system; the vertebral maturational status was evaluated using a six-stage stratification (CVM method). Ordinal regression was used to study the ability of the synchondrosis stage to predict the vertebral maturation stage. Vertebrae and synchondrosis had a strong significant correlation (r = 0.89) that essential was similar for females (r = 0.88) and males (r = 0.89). CVM stage could be accurately predicted from synchondrosis stage by ordinal regression models. Prediction equations of the vertebral stage using synchondrosis stage, sex and biological age as predictors were developed. Thus this investigation demonstrated that the stage of spheno-occipital synchondrosis, as determined in CBCT images, is a reasonable indicator of growth maturation.

Objectives To investigate the previously unreported presence of calcitonin (CT) levels in gingival crevicular fluid (GCF), its variations during initial orthodontic tooth movement in both tension and compression sites, and its possible association with the experienced dental pain. Design Fifteen children (mean age: 12.6 years) requiring orthodontic closure of the upper midline diastema were included. We collected GCF from the compression and tension sites of the upper right central incisor (experimental) and first bicuspid (control), before and after (1 h, 24 h, 7 d, 15 d) beginning of treatment. Calcitonin levels were determined by Western blot. Pain intensity was assessed using a visual analogue scale. Results Calcitonin levels were higher in the compression site versus the control site at 7 d (p = 0.014). Intragroup comparisons showed an increment of CT between 1 h and 7 d (680.81 ± 1672.60 pg/30 s, p = 0.010) in the compression site. No significant changes were found in the tension and control sites. Calcitonin levels and pain intensity were negatively associated during the period from 24 h to 15 d (r = −0.54, p = 0.05). Conclusions CT levels in the GCF significantly increased in the compression site after the short term after application of orthodontic forces. These changes were negatively associated with the perceived patient's dental pain during the period from 24 h to 15 d.

Objective: To analyse the changes in nasal air flow and school grades after rapid maxillary expansion (RME) in oral breathing children with maxillary constriction. Material and Methods: Forty-four oral breathing children (mean age 10.57 y) underwent orthodontic RME with a Hyrax screw. Forty-four age-matched children (mean age 10.64 y) with nasal physiological breathing and adequate transverse maxillary dimensions served as the control group. The maxillary widths, nasal air flow assessed via peak nasal inspiratory flow (PNIF), and school grades were recorded at baseline, and 6 months and one year following RME. Results: After RME, there were significant increases in all the maxillary widths in the study group. PNIF was reduced in the study group (60.91 ± 13.13 l/min) compared to the control group (94.50 ± 9.89 l/min) (P < 0.000) at the beginning of the study. Six months after RME, a significant improvement of PNIF was observed in the study group (36.43 ± 22.61). School grades were lower in the study group (85.52 ± 5.74) than in the control group (89.77 ± 4.44) (P < 0.05) at the baseline, but it increased six months after RME (2.77 ± 3.90) (P < 0.001) and one year later (5.02 ± 15.23) (P < 0.05). Conclusions: Nasal air flow improved in oral breathing children six months and one year after RME. School grades also improved, but not high enough to be academically significant. Key words:Maxillary constriction, oral breathing, nasal air flow, rapid maxillary expansion, school grades.

Introduction: Although chincups are the preferred treatment for growing children with mandibular prognathism, the mechanism by which chincups improve this condition remains unclear. The aim of this study was to use geometric morphometrics to evaluate changes in the shape of the mandible of prognathic children treated with a chincup. Methods: Geometric morphometrics were used to evaluate the short-term mandibular shape changes in 50 prognathic children treated with chincups compared with 40 untreated matched controls. Twenty-one 2-dimensional mandibular landmarks from cephalograms taken before and after 36 months of treatment or observation were analyzed by Procrustes superimposition and thin plate spline. Results: Permutation tests of the treated patients showed highly significant differences in the mandibular shapes before and after treatment, and compared with the control group after the observation period. The thin plate spline grid deformations indicated more rectangular mandibular configuration, forward condyle orientation, condyle neck compression, gonial area compression, and symphysis narrowing. Conclusions: Early chincup treatment widely modifies the mandibular shape of prognathic children to improve Class III malocclusion. Copyright © 2011 by the American Association of Orthodontists.

Objectives To evaluate and compare electromyographic activity of jaw muscles at rest and during maximal voluntary clenching in maximal intercuspation between growing individuals with unilateral posterior cross-bite without functional mandibular lateral shift during closure and matched individuals with normal occlusion. These findings may help elucidate the impact of this occlusal condition on jaw muscle function and the therapeutic implications. Design 30 growing children (10–12 years) with unilateral cross-bite without functional mandibular lateral shift during closure (cases) and 30 age- and sex-matched children with normal occlusion (controls) were consecutively selected applying highly restrictive criteria. Electromyographic activity coming from the areas of right and left anterior temporalis, posterior temporalis, masseter, and supra-hyoid muscles was evaluated at rest and during clenching. The asymmetry index was calculated for each muscle area to quantify the degree of asymmetry between sides. The masseter/anterior temporalis ratio during clenching was also recorded. Results No significant differences were found between groups at rest. During clenching, activity of the cross-bite side masseter area was significantly lower in cases versus controls but no difference was found between cross-bite and non-cross-bite sides of this muscle. Conclusions Unilateral posterior cross-bite without functional mandibular lateral shift is associated with a lower electromyographic activity of masseter muscle area of the cross-bite side during maximal clenching in maximal intercuspation, compared to the children with normal occlusion. This result could suggest a functional adaptation that should be carefully considered. Long-term studies are needed to determine future repercussions and to evaluate the benefit of an early treatment.

Objective This study aims to evaluate the relationship between the total antioxidant capacity of saliva and the presence of dental caries in deciduous and permanent teeth, in a group of Saharan children. Methods The dental examination was carried out in accordance with the recommendations of the World Health Organization (WHO). The total antioxidant capacity of the saliva was determined by colorimetry. Results The total antioxidant capacity (TAC) of the saliva of patients with caries in deciduous teeth was 2.89 1/IC50 greater than among those without. We observed a statistically significant linear regression between the number of deciduous teeth affected by caries and the total antioxidant capacity of the saliva: y = 0.24 + 0.53 × TAC saliva (t = 2.93; p = 0.004) (95% CI of b: 0.018-0.088). Conclusions Our results show that the amount of caries in deciduous teeth is in direct proportion to the observed TAC of saliva, and that the presence of caries in deciduous teeth is associated with caries in permanent teeth.

It is generally assumed that children with posterior crossbites have abnormal mandibular movements; however, this assumption has not been clearly evaluated. The purpose of this investigation was to study the movements and the resting position of the mandible in 2 samples of 30 subjects, one aged 10 to 14 years with right posterior crossbite, the other aged 10 to 15 years with normal occlusion. Subjects in both groups exhibited a Class I skeletal relationship and mesofacial growth pattern. A mandibular kinesiograph was used to record both the mandibular resting position and dynamic movements. Mandibular movements were recorded during (1) maximum excursions (opening-closing, protrusion, right and left excursions), (2) swallowing, and (3) mastication. The results showed no differences between groups in the extension of the movements during closing and protrusion. However, crossbite patients exhibited a significant lateral shift during these movements. Right and left excursions were also similar between groups. The dimension of the freeway space was similar between groups, but the lateral shift found in centric occlusion was also present in the crossbite group when the mandible was at rest. The crossbite group more frequently showed a pattern of abnormal swallowing. No differences were found in any of the parameters studied during the masticatory cycle. There was no relationship between the side of the crossbite and the masticatory preference side. In conclusion, posterior crossbite patients showed a lateral shift in some movements that persisted when the mandible was at rest.

Studies dealing with the electromyographic activity of masticatory muscles in patients with unilateral posterior crossbite are infrequent. The purpose of this study was to assess the electromyographic pattern of masticatory muscles at rest position, during swallowing, and during mastication, in 30 subjects with right posterior crossbite and to compare them to 30 normocclusive subjects. The 2 groups were matched according to age, gender, skeletal Class I, and mesofacial growth pattern. Electromyographic activity of right and left anterior temporalis, posterior temporalis, masseter, and anterior digastric muscles was recorded at rest position, while swallowing water, and while chewing. Disposable bipolar surface electrodes were used in both groups. Data were compared between groups and between right and left sides within each group. The results revealed that the posterior temporalis of the non-crossbite side was more active than that of the same side in subjects with crossbite at rest position and during swallowing. The activity of both anterior digastrics was higher in the crossbite subjects during swallowing. During chewing the right masseter muscle was less active in the crossbite patients than in normocclusive subjects. The results obtained during chewing indicate a bilateral masticatory pattern in both groups.