Functional treatment of bilateral posterior crossbite improves mandibular kinematics during chewing.

OBJECTIVES: To evaluate the effects of treatment of bilateral posterior crossbite (BPXB) on mandibular kinematics by the percentage of reverse chewing cycles (RCCs) during soft and hard bolus chewing before and after the correction of the malocclusion with function-generating bite (FGB). MATERIALS AND METHODS: This prospective study included 71 subjects: 19 patients with occlusally symmetric BPXB (M = 9; F = 10; mean age 9.3 ± 2.2[yr.mo]), 32 patients with occlusally asymmetric BPXB (19 with more teeth in crossbite on the right side (right prevalent side), M = 7; F = 12; mean age 8.2 ± 1.6 [yr.mo] and 13 on the left side, M = 7; F = 6; mean age 9.6 ± 1.9 [yr.mo]) and 20 controls without malocclusion (M = 8; F = 12; mean age 10.2 ± 1.7 [yr.mo]). Masticatory patterns were recorded before (T0) and after (T1) the correction of the malocclusion with FGB, with the K7-I® kinesiograph using standardized soft and hard boluses. RESULTS: BPXB was corrected in all included patients. At T0, the percentage of RCCs in BPXB was significantly increased compared to controls (P < .0001); symmetric BPXB showed no difference in RCCs between the sides, whereas asymmetric BPXB showed significantly more RCCs on the side with more teeth in crossbite (prevalent side). After treatment with FGB (T1), the percentage of RCCs was significantly reduced in both symmetric BPXB patients (soft bolus, P = .003; hard bolus, P < .001) and asymmetric BPXB patients (prevalent side: soft and hard bolus, P < .00001; non-prevalent side: soft bolus, P = .01 and hard bolus, P = .0002). CONCLUSION: Functional correction of BPXB with FGB significantly improved mandibular kinematics during chewing.

Effects of Contact Sports on Temporomandibular Disorders: An Observational Study.

The study investigated the prevalence of temporomandibular disorders in 100 competitive athletes in contact sports, equally grouped by the practiced game: Soccer (SoG), Rugby (RG), American Football (AFG), Boxing (BoG), Basketball (BaG), compared to a randomly control group of 20 non-athletes (CG). Symptoms and signs were examined according to the standardized Diagnostic Criteria for Temporomandibular Disorders through a questionnaire and clinical evaluation. Arthralgia showed significant differences between RG and CG and between AFG and CG (p < 0.05). Study groups reported masticatory muscle pain during function, neck and shoulder pain more frequently than CG, except for BoG. Closing click was significantly more present in study groups than CG, while crepitation was significantly higher only in RG and AFG. The deviation was wider in SoG, RG and AFG compared to CG (p < 0.05). Tukey's multiple comparisons test showed a statistically significant reduction in right laterotrusion in RG vs. CG (p < 0.05); the comparison showed a decrease in right laterotrusion in RG vs. SoG and BoG (p < 0.05), a decrease in endfeel in RG vs. CG, BaG and AFG (p < 0.05). The data seem to support a relationship between the prevalence of TMD symptoms and signs in competitive athletes in contact sports, especially in RG and AFG compared to CG.

Evaluation of masticatory function in patients with cleft lip and/or palate.

The aim of this study was to evaluate the masticatory pattern in children with cleft lip and/or palate (CL/P) through investigation of the prevalence of reverse sequencing chewing cycles. The study group included 18 patients with CL/P (mean age: 7.4 yr, SD: 1.4 yr), 15 of whom had dental crossbite. The controls included a group of 18 non-CL/P children with the same types of crossbite as the study group (mean age: 7.2 yr, SD: 1.5 yr) and a group of 18 non-CL/P subjects with normal occlusion (mean age: 9.8 yr, SD: 1.9 yr). Mandibular movements during chewing of soft and hard bolus were recorded with a kinesiograph. Kinematic signals were analysed using a custom-made software. A statistical analysis was performed to compare the degree of reverse-sequencing chewing cycles between patients and controls (Kruskal-Wallis test with Dwass-Steel-Critchlow-Fligner pairwise comparisons post hoc test). A significant difference between patients with CL/P and non-CL/P subjects with normal occlusion was highlighted on the left side of mastication, which was the side with the higher prevalence of crossbite with both types of bolus. No statistical differences were found between CL/P patients and healthy controls with crossbite. Cleft-affected patients with posterior crossbite exhibited an anomalous masticatory pattern with increased reverse chewing cycles on the crossbite side.

Thoracic-lumbar-sacral spine sagittal alignment and cranio-mandibular morphology in adolescents.

PURPOSE: The relationship between thoracic-lumbar-sacral spine sagittal alignment and craniofacial morphology is still controversial. Evidence-based results are difficult to obtain and scientific studies are inhomogeneous. The aim of this study was to investigate the difference of thoracic-lumbar-sacral spine posture and cephalometric values comparing two groups of subjects with different cranial structure in the sagittal plane. METHODS: Eighty-one subjects were consecutively selected and divided into two groups, according to the orientation of the condyle-orbital plane (CoOr) with respect to the superior maxilla (SpP): Group1: 49 subjects 11.6 (2.1) years showing posterior-rotation of CoOr: SpP^CoOr ≤ -2°, -4.1°(2.1°); Group2: 32 subjects 12.9 (2.3)years showing anterior-rotation of CoOr: SpP^CoOr ≥ 2°, 3.7°(1.9°). Each patient underwent in blinding, Spinal Mouse recording and cephalometry of the skull. RESULTS: Group1 showed a significant forward tilting of the spine 4.4°(1.8°) with respect to Group2 2.4°(1.3°) (p < 0.0001) and higher values related to the vertical dimension of the skull: higher maxillary divergency (p < 0.0001), steep occlusal plane (p < 0.0007), higher gonial angle (p < 0.001). DISCUSSION: The results of this study showed a difference in the thoracic-lumbar-sacral spine inclination between groups with different craniofacial morphology. The achievement of this outcome is important to improve our multidisciplinary evaluation and treatment planning.

Effects of therapy on masseter activity and chewing kinematics in patients with unilateral posterior crossbite.

OBJECTIVE: To describe the effects of therapy on masseter activity and chewing kinematic in patients with unilateral posterior crossbite (UPC). DESIGN: Fifty children (age: mean ± SD: 9.1 ± 2.3 years) with UPC (34 on the right side, 16 on the left side) and twenty children (age: 9.5 ± 2.6 years) with normal occlusion were selected for the study. The mandibular motion and the muscular activity during chewing soft and hard boli were simultaneously recorded, before and after correction with function generating bite, after a mean treatment time of 7.3 ± 2.4 months plus the retention time of 5-6 months. The percentage of reverse cycles and the percent difference between ipsilateral and contralateral peaks of the masseter electromyography envelopes were computed. RESULTS: Before therapy, the percentage of reverse cycles during chewing on the crossbite side was greater in patients than in controls (P<0.001) and significantly reduced after therapy (P<0.001) towards the reference normal value (soft bolus; pre: 57 ± 30%, post:12 ± 17%; hard bolus; pre: 65 ± 34%, post: 12 ± 13%; reference value: soft bolus 4 ± 2%, hard bolus 5 ± 3%). Before therapy the percent difference between electromyography envelope peaks in patients was lower than in controls (P<0.01) and significantly increased after therapy (P<0.05) becoming similar to the reference normal value. CONCLUSIONS: The correction induced a normal-like coordination of masseter muscles activity together with a significant reduction of the reverse chewing patterns. The previous altered muscular activation corresponded to the altered kinematics of reverse chewing cycles that might be considered a useful indicator of the severity of the masticatory function involvement.

Changes in electric activity of masseter and anterior temporalis muscles before and after orthognathic surgery in skeletal class III patients.

OBJECTIVE: The purpose of this study was to evaluate, through clinical and electromyographic (EMG) assessments, the electric activity of masseter muscle and anterior temporalis muscles during clenching, before and after orthodontic treatment and mandibular setback, with or without LeFort I osteotomy, for correction of mandibular excess. STUDY DESIGN: Seventeen adult patients (10 males, 7 females, mean age: 22.5 ± 2.4 years) were recruited for this study. All patients received orthodontic treatment and surgical corrections. EMG recordings were obtained from 4 channels of the 8-channel electromyograph FREELY (DeGoetzen spa, Olgiate Olona, VA, Italy). RESULTS: A significant difference was found in the value of activity index at T0-T1 (33% T0, 1% T1) (P < .05), of asymmetry index at T0-T1 (21% T0, 4% T1) (P < .05), and of torque index at T0-T1 (24% T0, 5% T1) (P < .05). CONCLUSIONS: The evaluation of EMG activity after surgery may be considered a sign of good adaptation of the neuromuscular system to the new occlusal condition and a good method for detecting nonresponding patients who might require further treatment.