Relationship between masseter muscle activity during wakefulness and temporomandibular disorder-related symptoms.

BACKGROUND: Masseter muscle activity during wakefulness may be associated with temporomandibular disorder (TMD)-related symptoms, psychosocial status and pain-related disability; however, this relationship is unclear. OBJECTIVES: This study aimed to determine the relationship between masseter muscle electromyography (EMG) burst/duration during wakefulness and TMD-related symptoms, psychosocial status and pain-related disability. METHODS: Sixty participants were assessed masseter muscle activity during wakefulness using a data-logger-type ultraminiature EMG system and TMD-related symptoms, psychosocial status and pain-related disability through Axis I and II of the diagnostic criteria for TMD (DC/TMD). EMG bursts lasting longer than 0.25 s but less than 2.0 s and those lasting longer than 2.0 s were classified as phasic and tonic bursts, respectively. RESULTS: Participants with palpation-related pain in the temporalis and masseter muscles, as assessed through the DC/TMD examination form in Axis I, had more bursts (number/h) (p = .035 and p = .009, respectively) and longer duration (time/h) (p = .013 and p = .004, respectively) of tonic bursts of the masseter muscle during wakefulness. Participants with palpation-related pain in the masseter muscles had higher oral behaviour scores during wakefulness using Axis II (p = .001), which affected the number and duration of tonic bursts of the masseter muscle activity during wakefulness (p = .011 and p = .007, respectively). CONCLUSION: As tonic bursts mainly reflect clenching, individuals with pain in the masseter muscles by palpation may have a high frequency and longer duration of clenching, as well as a high frequency of oral behaviours during wakefulness.

A novel auxiliary device enhances miniscrew stability under immediate heavy loading simulating orthopedic treatment.

OBJECTIVES: To evaluate miniscrew stability and perform a histomorphometric analysis of the bone around the miniscrew under a load corresponding to orthopedic force. MATERIALS AND METHODS: Thirty-two miniscrews were implanted into eight rabbit tibias. Auxiliary group rabbits received auxiliary devices with miniscrews (n = 8, 28 days; n = 8, 56 days), and those in the nonauxiliary control group received miniscrews without auxiliary devices (n = 8, 28 days; n = 8, 56 days). Elastics were placed between miniscrews to apply a load of 5 N. Miniscrew stability was evaluated using a Periotest. Bone-to-implant contact (BIC) and spike implantation depth were measured histomorphologically. RESULTS: Periotest values in the auxiliary group were significantly lower than those in the nonauxiliary group at all time periods. There was no significant difference in BIC between the auxiliary and nonauxiliary groups at 28 or 56 days postimplantation. The implantation spike depth in the auxiliary group was significantly greater at 56 days compared to that at 28 days. Newly formed bone was observed around the spike of the auxiliary device at 56 days. CONCLUSIONS: The results suggest that the use of miniscrews in conjunction with auxiliary devices provides stable skeletal anchorage, which may be useful in orthopedic treatments.

Effects of sex, age, choice of surgical orthodontic treatment, and skeletal pattern on the psychological assessments of orthodontic patients.

We aimed to examine the effects of sex, age, choice of surgical orthodontic treatment, and skeletal pattern on psychological assessment scores of orthodontic patients before edgewise treatment. They completed the State-Trait Anxiety Inventory (STAI), Beck Depression Inventory (BDI)-II, and the psychological domain of the World Health Organization Quality of Life 26 (Psych-QOL) for assessment of anxiety, depression, and body image, respectively. No significant effects on psychological assessment scores due to sex or age differences were found. Surgical orthodontic treatment patients and patients with skeletal Class III had significantly higher STAI-Trait and/or BDI-II scores and lower Psych-QOL score. Based on the linear mixed-effects model, the choice of surgical orthodontic treatment had a significant effect on the STAI-Trait, BDI-II, and Psych-QOL scores. No significant interaction effect was found between the choice of surgical orthodontic treatment and the skeletal pattern by ANB angle. Patients with skeletal Class I or III who chose surgical orthodontic treatment had higher STAI-Trait and/or BDI-II scores and/or lower body image score, respectively. These results suggest that patients who chose surgical orthodontic treatment, particularly those with skeletal Class I and III, may be more prone to experience anxiety and depression and have body image dissatisfaction.

A Follow-Up Study on the Clinical Outcomes of Alveolar Reconstruction Using Octacalcium Phosphate Granules and Atelocollagen Complex.

PURPOSE: To observe the long-term postoperative bone formation and eruption of adjacent teeth after octacalcium phosphate granule and atelocollagen complex (OCP/Col) grafting in the treatment of alveolar cleft of patients with unilateral cleft lip with or without cleft palate (UCL ± P). METHODS: Four patients with UCL ± P who underwent OCP/Col grafting (OCP group), and 55 patients with UCL ± P who underwent autologous bone grafting (AB group) were enrolled in this study. OCP/Col or autologous bone grafting was performed before the eruption of canines or lateral incisors in mixed dentition, followed by orthodontic management. Patients in the OCP group underwent radiography before and after surgery at 1, 2, 3, 6, and over 30 months postoperatively. The volume and area of the bony defect in the alveolar cleft area were compared between the OCP and AB groups before and after 6 months of surgery. RESULTS: The bone bridge in all patients in the OCP/Col group was successfully formed, and by 6 months postoperatively, the permanent teeth adjacent to the alveolar cleft had erupted at the site of the OCP/Col complex graft. Comparison of the pre- and postoperative bone defects between the 2 groups revealed almost the same extent of bone bridge formation. CONCLUSIONS: OCP/Col grafting could be considered as an alternative to autologous bone grafting as it yielded successful bone bridge formation and facilitated permanent tooth eruption.

Effects of intra-oesophageal acid infusion and a stress task on masseter muscle activity and autonomic nervous activity in wakefulness.

BACKGROUND: Gastroesophageal reflux disease may be an important risk factor for awake bruxism. Additionally, it has been known that a psychological stress task affects masseter muscle activity, and autonomic nervous system (ANS) activity modulation induces masseter muscle activity. OBJECTIVES: This study aimed to investigate whether task-induced stress and experimental oesophageal acid infusion increase masseter muscle activity and alter ANS activity, compared to rest task and oesophageal saline infusion, respectively. METHODS: Polygraphic monitoring, consisting of electromyography of the masseter muscle and electrocardiography, was performed in 12 healthy adult men during 30-min interventions with intra-oesophageal saline or acid infusion, while reading a book quietly, as rest, and while performing calculation, as a stress task. RESULTS: At rest, masseter muscle activity and parasympathetic nervous system (PNS) activity during acid infusion were significantly higher (P = .019) and lower (P = .021) than during saline infusion, respectively. During saline infusion, both masseter muscle activity and sympathetic nervous system (SNS) activity or PNS activity while performing the calculation task were higher (P = .022 and .012, respectively) or lower (P = .007) than those during the reading task, respectively. In two-way repeated-measures ANOVA, intra-oesophageal infusion (saline or acid) significantly affected masseter muscle activity (P = .008) and PNS activity (P = .021). However, performing tasks (reading or calculation) significantly affected only PNS activity (P = .028). CONCLUSION: Intra-oesophageal acid infusion significantly increased masseter muscle activity and decreased PNS activity. In contrast, stress task not only significantly decreased PNS activity, but only modestly increased masseter muscle activity and SNS activity.

Relationships of maxillofacial morphology and malocclusion with handgrip strength in adult women.

OBJECTIVES: Maxillofacial morphology and malocclusion are related to maximum occlusal force (MOF). Although it has been reported that MOF was related to handgrip strength (HS), the relationships between maxillofacial morphology/malocclusion and HS remain unclear. This study aimed to examine the relationships between maxillofacial morphology, malocclusion and HS. SETTING AND SAMPLE POPULATION: Eighty-five women with malocclusion, aged 18-40 years, were selected. MATERIALS AND METHODS: Lateral cephalometric radiographs (SNA, SNB, ANB, mandibular plane-FH, and gonial angles, overjet and overbite), the Peer Assessment Rating (PAR) index and HS were measured. Subjects were classified by the Japanese normal mean value of cephalometric analysis or the reference value which was defined by degree of malocclusion in each PAR index measurement item (small/low: value < mean/reference value, large/high: value ≧ mean/reference value). Measurements were then compared between groups. RESULTS: HS of the large-gonial angle group was lower than that of the small-gonial angle group. In the small-overbite group or high-transverse (PAR index score showing crossbite/scissor bite in the canine and molars) group, HS in the large-gonial angle group was significantly lower than that in the small-gonial angle group. CONCLUSIONS: Our results suggest that gonial angle is the largest factor affecting HS. HS may be especially low in those subjects with a large gonial angle and a small overbite or a crossbite/scissor bite in the molar section.

Evaluation of maxillary central incisors on the noncleft and cleft sides in patients with unilateral cleft lip and palate-Part 1: Relationship between root length and orthodontic tooth movement.

OBJECTIVES: To measure the root lengths of maxillary central incisors (U1) and evaluate the relationship among U1 root length, tooth movement, and type of treatment appliance in patients with unilateral cleft lip and palate over a long-term follow-up period. MATERIALS AND METHODS: Occlusal radiographs of 30 patients with unilateral cleft lip and palate, acquired less than 6 months before secondary alveolar bone grafting (SBG, T1) and after edgewise treatment (T2), were measured for U1 root length (R1 and R2, root lengths at T1 and T2, respectively). Frontal and lateral cephalometric radiographs acquired at eruption of U1 (T0), T1, and T2 were evaluated to determine the inclination and position of U1. RESULTS: The average values of R1 and R2 on the cleft side were significantly lower than those on the noncleft side. Frontal cephalometric analysis revealed that the horizontal distance of the root apex from the median vertical line at T0 on the cleft side was significantly smaller than that on the noncleft side and was correlated with short U1 root length on the cleft side. On the other hand, R1 in patients treated with maxillary protraction appliances between T0 and T1 was significantly shorter than that in patients without maxillary protraction appliances. However, none of the changes in cephalometric measurements were correlated with root length. CONCLUSIONS: In patients with unilateral cleft lip and palate, the short root length of cleft-adjacent central incisors might be associated with the horizontal position of the root apex. In addition, orthodontic treatment with a maxillary protraction appliance before secondary alveolar bone grafting might be associated with short U1 root length.

Evaluation of maxillary central incisors on the noncleft and cleft sides in patients with unilateral cleft lip and palate-Part 2: Relationship between root resorption, horizontal tooth movement, and quantity of grafted autogenous bone.

OBJECTIVE: To evaluate the relationship between external apical root resorption (EARR) of the maxillary central incisors (U1), horizontal orthodontic tooth movement, and quantity of grafted bone in subjects with unilateral cleft lip and palate (UCLP) over an average duration of 8 years. MATERIALS AND METHODS: Thirty subjects with UCLP were evaluated for EARR of U1 after edgewise treatment (T2). The teeth were classified as having no EARR, moderate EARR (combined into "no/moderate" EARR), or severe EARR. Frontal cephalometric radiographs acquired at eruption of U1 (T0), less than 6 months before secondary alveolar bone grafting (T1), and T2 were evaluated to determine the horizontal inclination (U1-axis angle) and distance of the root apex from the median line (U1-root-VL distance). On the cleft side, the quantities of grafted bone at less than 12 months postsecondary bone grafting and at T2 were evaluated using the alveolar bone graft (ABG) scale. RESULTS: Cleft-adjacent teeth exhibited more severe EARR than did teeth on the noncleft side. The cleft side exhibited greater changes in U1-axis angle and U1-root-VL distance between T0 and T2 than did the noncleft side. On the cleft side, the ABG score at T2 in the severe EARR group was significantly lower than that in the no/moderate EARR group. These measurements were correlated with EARR grade. CONCLUSIONS: Cleft-adjacent U1 exhibited more severe EARR than did the U1 on the noncleft side, which might be associated with orthodontic treatment-induced changes in horizontal inclination and root apex movement. On the cleft side, severity of EARR may be correlated with the success of ABG.