Reverse-sequencing chewing patterns evaluation in anterior versus posterior unilateral crossbite patients.

It is well established that patients with a unilateral posterior crossbite exhibit reverse-sequencing chewing patterns when chewing on the affected side. The aim of the study was to compare the prevalence of reverse-sequencing chewing cycles in patients with anterior versus posterior unilateral crossbite during chewing soft and hard boluses. Eighty-six children (39 boys, 47 girls) were included in the study: 26 (10.4 ± 2.7 years) with unilateral anterior crossbite, 43 (10.2 ± 4.2 years) with unilateral posterior crossbite, and 17 (10.6 ± 2 years) with normal occlusion were selected for the study. Mandibular movements were measured with a kinesiograph (K7, Myotronics Inc. Tukwila). The kinematic signals were analyzed using custom-made software. The results showed a low prevalence of reverse-sequencing chewing cycles in patients with anterior crossbite, without any significant difference between sides and with the control group, with both soft (P = 0.33) and hard (P = 0.29) bolus. The patients with posterior unilateral crossbite showed a significant higher prevalence of reverse-sequencing chewing cycles during chewing on the crossbite side with respect to the non-crossbite side (P < 0.001) and to the control group (P < 0.001). Comparing the patients with anterior versus posterior unilateral crossbite, a significant difference (P < 0.001) in the prevalence of reverse chewing cycles was demonstrated during chewing on the posterior crossbite side only with both soft and hard bolus. In conclusion, patients with anterior versus posterior unilateral crossbite show different functional characteristics depending on which dental region is involved.

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.

Temporomandibular joint disorders during HIV infection: a case report.

Temporomandibular disorders (TMD) is a term reflecting chronic, painful, craniofacial conditions usually of unclear etiology with impaired jaw function. Human immunodeficiency virus (HIV)-infected patients often report chronic pain and pathologies targeting body joints during retroviral therapy. Although both conditions may share similar secondary disorders, no conclusive cause-effect relationship has been found linking the TMD to the HIV-antiviral treatment. This report describes a case of TMD associated with HIV infection during active retroviral therapy. Clinicians should be aware that treatment of an HIV-infected patient with TMD requires an interdisciplinary team approach.

Amelioration of pain and histopathologic joint abnormalities in the Col1-IL-1beta(XAT) mouse model of arthritis by intraarticular induction of mu-opioid receptor into the temporomandibular joint.

OBJECTIVE: To evaluate opioid receptor function as a basis for novel antinociceptive therapy in arthritis. METHODS: We induced human mu-opioid receptor (HuMOR) expression in arthritic joints of mice, using the feline immunodeficiency virus (FIV) vector, which is capable of stably transducing dividing, growth-arrested, and terminally differentiated cells. Male and female Col1-IL-1beta(XAT)-transgenic mice developed on a C57BL/6J background and wild-type littermates were studied. RESULTS: A single injection of FIV(HuMOR) into the temporomandibular joints of Col1-IL-1beta(XAT)-transgenic mice 1 week prior to induction of arthritis prevented the development of orofacial pain and joint dysfunction, and reduced the degree of histopathologic abnormality in the joint. In addition, FIV(HuMOR) prevented the attendant sensitization of trigeminal sensory neurons and activation of astroglia in brainstem trigeminal sensory nuclei. These effects were mediated by the transduction of primary sensory neurons via transport of FIV vectors from peripheral nerve endings to sensory ganglia, as evidenced by HuMOR expression in neuronal cell bodies located in the trigeminal ganglia, as well as in their proximal and distal nerve branches located in the main sensory and subnucleus caudalis of the brainstem and joints, respectively. The presence of MOR ligands predominantly in the descending trigeminal nucleus suggested that the observed antinociception occurred at the subnucleus caudalis. Articular chondrocytes and meniscal tissue were also infected by FIV(HuMOR), which presumably exerted an antiinflammatory effect on cartilage. CONCLUSION: Our results indicate that prophylactic therapy with MOR overexpression in joints can successfully prevent the development of pain, dysfunction, and histopathologic abnormalities in the joints in arthritis. These findings may provide a basis for the future development of spatiotemporally controlled antinociceptive and antiinflammatory therapy for arthritis.

Quantitative analysis of the variability of unilateral chewing movements in young adults.

Kinesiography can be used as a diagnostic tool in a dental clinic context. In the current study, a kinesiograph was used to detect and record the three-dimensional motion of the mandibular mid-incisor point during unilateral chewing as a function of time. The aim of the study was to quantify the within-subject short-term reproducibility of the kinesiographic recordings in normal, healthy subjects. Ten seconds of unilateral (right and left) gum chewing were recorded in 20 control subjects using computerized kinesiography. Each subject performed 18 chewing sequences (three repetitions x three sessions x two sides). Chewing cycle duration, volume, standardized depth and width, and the number of reversed cycles were calculated. Intraclass correlation coefficients (two-way random effects analysis of variance with interactions) and paired t-tests were used to compare sessions. For each subject and side, chewing variability was expressed as the coefficient of variation (percentage ratio of standard deviation to mean) of each variable. Mean left and right side mastications were computed over all sessions and subjects. For all the analyzed variables, larger variations between subjects (analysis of variance, p < 0.001) than between sessions were found, with intraclass correlation coefficients ranging between 0.432 (left side cycle duration) and 0.989 (right side standardized width). No systematic errors between the three measurement sessions were found for cycle volume and shape (paired t, p > 0.05). The highest between subjects/ between sessions variance ratios (up to 223.28) were found for cycle duration and shape. In all subjects, chewing cycle volume was very variable, with mean coefficients of variation up to 47% (left side in females). Cycle duration and standardized depth and width were more reproducible, with mean coefficients of variation up to 10% (duration), 14% (standardized width), and 18% (standardized depth). The spatial characteristics of gum chewing cycles had a large within-subject variability. The temporal and size-standardized (shape) characteristics were more consistent within subject. The results should allow selection of a set of relatively more consistent variables for the definition of normality and the comparison of patients.