Establishment of a new rehabilitation program using masticatory training food for jaw deformity patients.

Background/purpose: Patients with jaw deformities may show a reduction in masticatory function as a result of postoperative hypofunction. This study aimed to establish a novel rehabilitation program using a commercially available masticatory training food for patients with jaw deformities after orthognathic surgery. Materials and methods: Nine patients with mandibular prognathism (the training group: n = 5, and the non-training group: n = 4) and 6 control participants with normal occlusion were included in this study. For the rehabilitation program with masticatory exercise, patients were instructed to chew the training food once a day for 60 days starting from 10 days after the surgery. The effects of the rehabilitation program were assessed by determining the maximum bite force (MBF) and the masticatory performance (MP). Clinical assessments were performed just before orthognathic surgery (Pre) and at 10 days (T0), 1 month (T1), 2 months (T2), and 3 months (T3) after surgery. Results: Compared with the non-training group, the training group showed a trend toward greater recovery amount of MBF from Pre to T3, and a significantly greater recovery amount in MP (p < 0.05) from Pre to T3. When the time-series change of MP was evaluated in both groups from T0 to T3, a significant difference was observed in the interaction terms (p = 0.03). This result indicates that the effectiveness of the training may be demonstrated by following the postoperative course further. Conclusion: The rehabilitation using this training food may become a useful method for postoperative hypofunction in patients with jaw deformities.

Treatment decision of camouflage or surgical orthodontic treatment for skeletal Class III patients based on analysis of masticatory function.

Background/purpose: Surgical orthodontic treatment is recommended for patients with severe dentoskeletal discrepancies, while camouflage orthodontic treatment is recommended for patients with mild to moderate discrepancies. However, the decision as to which treatment should be chosen is complicated. The purpose of this study was to determine differences in masticatory function in patients who underwent camouflage and surgical orthodontic treatment for skeletal Class III malocclusion, as well as the usefulness of Wits appraisal in treatment decision based on masticatory functional analysis. Materials and methods: The study subjects were 45 patients with skeletal Class III malocclusion (15 cases with camouflage orthodontics and 30 cases with orthognatic surgery) and 12 individuals with normal occlusion. We analyzed the pre-treatment records of electromyographic activities of masseter and temporalis muscles and jaw movements. Results: There were no significant differences in various functional measurements between the camouflage and surgery groups. However, there were significant but not strong correlations between ANB and both masseter muscle activity (r = 0.36, p < 0.01) and expression ratio of abnormal chewing (r = -0.54, p < 0.01). Division of patients into two groups using a cutoff value of -6.0 mm for Wits appraisal showed a significant difference in masseter muscle activity between -6.0 mm or less group and the control (p < 0.01) but none between more than -6.0 mm group and the control. Conclusion: Camouflage orthodontic treatment is inappropriate for patients with relatively severe dentoskeletal discrepancies. Wits appraisal of -6.0 mm is a potentially useful parameter for treatment decision.

Effects of functional training after orthognathic surgery on masticatory function in patients with mandibular prognathism.

BACKGROUND/PURPOSE: Even after surgical orthodontic treatment, the level of masticatory function in patients with jaw deformities is still lower than that of healthy subjects. The purpose of this study was to evaluate the effects of functional training program using gum chewing exercise after orthognathic surgery on masticatory function in patients with mandibular prognathism. MATERIALS AND METHODS: The study subjects were 16 patients with mandibular prognathism who underwent orthognathic surgery and 8 individuals with normal occlusion. Patients were divided into two groups (training group and non-training group; n = 8 per group). Functional training included gum chewing exercise and patient-education about masticatory function. The training; gum chewing exercise of 5 min twice a day for 90 days, started at 3 months after surgery. For each subject, electromyographic activities of masseter and temporalis muscles during maximum voluntary clenching (MVC) and jaw movement during gum chewing were recorded before and after surgical orthodontic treatment. Two parameters; activity index (AI: ratio of activity of masseter and temporalis muscles) and error index (EI: ratio of the number of abnormal chewing patterns), were used. RESULTS: In the training group, the AI value during MVC increased significantly and the EI value during gam chewing decreased significantly after surgical orthodontic treatment (AI: p < 0.01; EI: p < 0.01), indicating the improvement of activity balance of masseter and temporalis muscles and conversion of the jaw movement from abnormal to normal pattern (p < 0.01). CONCLUSION: Our findings suggested that functional training using the gum chewing and patient-education exercise improved masticatory function in patients with mandibular prognathism.

Incorporation of plant residue-derived carbon into the microeukaryotic community in a rice field soil revealed by DNA stable-isotope probing.

The microbial decomposition of plant residue is a central part of the carbon cycle in soil ecosystems. Here, we explored the microeukaryotic community responsible for the uptake of plant residue carbon in a rice field soil through DNA-based stable-isotope probing (SIP) using dried rice callus labelled with (13) C as a model substrate. Molecular fingerprinting with PCR-DGGE showed that the total eukaryotic community in soil under drained (upland) conditions distinctly changed within 3 days after the callus was applied and stable thereafter. The predominant group of eukaryotes that incorporated callus carbon were fungi affiliated with the Mucoromycotina (Mortierella), Ascomycota (Galactomyces, Eleutherascus, Gibberella and Fusarium) and Zoopagomycotina (Syncephalis). 'Fungus-like' protists such as Pythium (stramenopiles) and Polymyxa (Cercozoa) were also involved in carbon flow from the callus. Some of these fungi and 'fungus-like' protists took up soil organic matter with time, which suggested a priming effect of the callus on the eukaryotic community. Our results demonstrated the usefulness of SIP not only to trace the carbon flow from fresh organic matter but also to study the effect of fresh organic matter on the utilization of soil organic matter by the microbial community.