The challenge of ecological validity in temporomandibular disorders research.

OBJECTIVE: To review the ecological validity of outcomes from current research involving temporomandibular disorders (TMDs), with an emphasis on chronic myofascial pain and the precocious development of degenerative disease of the temporomandibular joint (TMJ). MATERIALS AND METHODS: Current approaches used to study TMDs in terms of neuromechanics, masticatory muscle behaviours, and the dynamics of the autonomic nervous system (ANS) were assessed for ecological validity in this review. In particular, the available literature was scrutinized regarding the effects of sampling, environmental and psychophysiological constraints and averaging data across biological rhythms. RESULTS: Validated computer-assisted numerical modelling of the neuromechanics used biological objective functions to accurately predict muscle activation patterns for jaw-loading tasks that were individual-specific. With respect to masticatory muscle behaviour, current findings refute the premise that sustained bruxing and clenching at high jaw-loading magnitudes were associated with painful TMDs such as myofascial pain. Concerning the role of the ANS in TMDs, there remains the need for personalized assessments based on biorhythms, and where the detection of dysregulated physiologic oscillators may inform interventions to relieve pain and restore normal function. CONCLUSIONS: Future human research which focuses on TMD myofascial pain or the precocious development and progression of TMJ degenerative joint disease requires experimental designs with ecological validity that capture objectively measured data which meaningfully reflect circadian and ultradian states.

Outcome assessment of orthodontic clear aligner vs fixed appliance treatment in adolescents with moderate to severe malocclusions.

OBJECTIVE: To compare the efficacy and efficiency of treatment with clear aligners (CAT) vs fixed appliances (FAT) in adolescents with Class I and II moderate to severe malocclusions. MATERIALS AND METHODS: One operator's (Garfinkle) cases from 2014 to 2019, started at age 12-18 years, with pre- and posttreatment records were identified and used according to an institutional review board-approved protocol. Records were measured by two calibrated, blinded investigators, aided by software (OrthoCAD [Cadent, Fairview, N.J.], Dolphin Imaging & Management Solutions [Chatsworth, Calif]). Discrepancy index (DI) and cast radiograph evaluation (CRE) scores, treatment duration, number of scheduled and emergency visits, and reported appliance and interarch elastic wear compliance were compared between groups using Wilcoxon rank sum and Fisher's exact tests. Cephalometric superimpositions were completed to evaluate craniofacial growth and dental changes. RESULTS: Records from 72 cases met the criteria and were included. For the 47 CAT and 25 FAT cases, mean DI (21 ± 5 and 24 ± 8, respectively; P = .20) and CRE (35 ± 10 and 34 ± 9, respectively; P = .90) scores were not significantly different. Other case attributes and reported appliance and interarch elastic wear compliance were also not significantly different. CAT vs FAT cases had significantly smaller treatment durations (24 ± 6 vs 27 ± 5 months; P = .01) and visit numbers (16 ± 5 vs 24 ± 4; P < .01), but emergency visit numbers were not significantly different (2 ± 2 vs 3 ± 2; P = .08). CONCLUSIONS: In adolescents with Class I and II malocclusions and moderate to severe DI scores, on average, CAT vs FAT cases were completed 3 months faster with eight fewer visits, but treatment efficacy was not significantly different.

Orthognathic surgery effects on temporomandibular joint compressive stresses.

INTRODUCTION: This study tested orthognathic surgery effects on temporomandibular joint (TMJ) compressive stresses. METHODS: Pre- (T1) and post-surgery (T2) cone-beam computed tomography images were collected from consenting subjects aged ≥15 years. Anatomical data were used to measure surgical changes in anteroposterior mandibular position and occlusal plane angle (FH-OP), estimate condylar loading areas (mm2 ) and calculate T1 and T2 TMJ and jaw muscle forces (N) during canine biting via numerical modelling. Analysis of covariance tested for sex and biting angle differences in T2 - T1 TMJ compressive stresses (TMJ force/loading area, MPa). Principal component analyses identified jaw muscle forces that accounted for changes in T2 - T1 TMJ loads. Regression analyses tested the correlations between surgical changes in mandibular position, FH-OP, TMJ loads and muscle forces. RESULTS: Of 148 cases screened, 28 females and 16 males provided complete records. Condylar loading areas were significantly smaller (P = .024) for females vs males (124 ± 5 vs 144 ± 7 mm2 ). T2 - T1 differences in TMJ compressive stresses varied by surgical change, biting angle and sex. Overall, the largest increases in TMJ compressive stresses post-surgery were for females with mandibular setbacks where FH-OP angle decreased. T2 - T1 changes in jaw muscle forces had moderate (ipsilateral, λ = 4.59; η2 = 0.071) to large (contralateral, λ = 1.49; η2 = 0.31) effects on TMJ loads. CONCLUSIONS: T2 - T1 differences in TMJ compressive stresses during canine biting were affected by surgical changes in mandibular position and occlusal plane angle, biting angle and sex. Surgical changes altered jaw muscle forces for the same biting conditions and, thus, affected TMJ loads and compressive stresses.

A theoretical analysis of longitudinal temporomandibular joint compressive stresses and mandibular growth.

OBJECTIVES: To determine if temporomandibular joint (TMJ) compressive stresses during incisor biting (1) differed between growing children over time, and (2) were correlated with Frankfort Horizontal-mandibular plane angle (FHMPA, °) and ramus length (Condylion-Gonion (Co-Go), mm). MATERIALS AND METHODS: Three-dimensional anatomical geometries, FHMPA and Co-Go, were measured longitudinally from lateral and posteroanterior cephalographs1 of children aged 6 (T1), 12 (T2), and 18 (T3) years. Geometries were used in numerical models to estimate subject-specific TMJ eminence shape and forces for incisor bite-forces of 3, 5, and 8 Newtons at T1, T2, and T3, respectively. TMJ compressive stresses were estimated via two steps: First, TMJ force divided by age-dependent mandibular condylar dimensions, and second, modified by loading surfaces' congruency. Analysis of variance and Tukey honest significant difference post-hoc tests, plus repeated measures and mixed effects model analyses were used to evaluate differences in variables between facial groups. Regression analyses tested for correlation between age-dependent compressive stresses, FHMPA, and Co-Go. RESULTS: Sixty-five of 842 potential subjects had T1-T3 cephalographs and were grouped by FHMPA at T3. Dolichofacial (FHMPA ≥ 27°, n = 36) compared to meso-brachyfacial (FHMPA< 27°, n = 29) subjects had significantly larger FHMPA at T1-T3, shorter Co-Go at T2 and T3 (all P < .01), and larger increases in TMJ compressive stresses with age (P < .0001). Higher compressive stresses were correlated with larger FHMPA (all R2 ≥ 0.41) and shorter Co-Go (all R2 ≥ 0.49). CONCLUSIONS: Estimated TMJ compressive stress increases from ages 6 to 18 years were significantly larger in dolichofacial compared to meso-brachyfacial subjects and correlated to FHMPA and Co-Go.

Expert consensus on Didactic Clinical Skills Development for orthodontic curricula.

PURPOSE/OBJECTIVE: Competence is expected of each beginning dentist and orthodontist. However, the broad definition of competence presents a challenge to academic programs in identifying the level of cognition for students to achieve competence. This study aimed to determine the Didactic Clinical Skills Development curriculum content and competency in predoctoral and advanced education orthodontic programs. METHOD: A modified Delphi method with a consensus threshold of 70% was employed using an expert panel of academic orthodontists. RESULTS: Round One (n = 26) identified that all topics proposed by a focus group were necessary, except for predoctoral Appliances, which was at 65%. Round Two (n = 23) included subtopics of Appliances to confirm the lack of consensus, plus subtopics of all the other topics and the level of cognition required for each subtopic. The expert panel reached a consensus that all 24 subtopics, hence all topics, were necessary. In Round Three, subtopic responses in Round Two were assigned a value between 1 (remember) and 6 (create) to generate a hierarchical level-of-learning scale. Mean values were calculated for each subtopic response. For all subtopics, the mean level of cognition for predoctoral education was at understand; for advanced education, it was at evaluate. CONCLUSION: This consensus suggests that, to be deemed competent, beginning dentists must learn these topics and subtopics in the cognitive domain of understand, and beginning orthodontists in the cognitive domain of evaluate. This study showed an expert consensus on Didactic Clinical Skills Development orthodontic curriculum content and a panorama of educational objectives that could be used as a template for curriculum design.

Mechanobehavior and mandibular ramus length in different facial phenotypes.

OBJECTIVES: To test the hypotheses that mechanobehavior scores (MBS) were correlated with mandibular ramus lengths (Co-Go) and differed between facial phenotypes. MATERIALS AND METHODS: Subjects gave informed consent to participate. Co-Go (mm), mandibular plane angles (SN-GoGn, °), and three-dimensional anatomy were derived from cephalometric radiography or cone beam computed tomography. Temporomandibular joint (TMJ) energy densities (ED) (mJ/mm3) were measured using dynamic stereometry and duty factors (DF) (%) were measured from electromyography, to calculate MBS (= ED2 × DF,) for each TMJ. Polynomial regressions, K-means cluster analysis, and analysis of variance (ANOVA) with Tukey post-hoc tests were employed. RESULTS: Fifty females and 23 males produced replete data. Polynomial regressions showed MBS were correlated with Co-Go (females, R2 = 0.57; males, R2 = 0.81). Cluster analysis identified three groups (P < .001). Dolichofacial subjects, with shorter normalized Co-Go, clustered into two subgroups with low and high MBS compared to brachyfacial subjects with longer Co-Go. SN-GoGn was significantly larger (P < .03) in the dolichofacial subgroups combined (33.0 ± 5.9°) compared to the brachyfacial group (29.8 ± 5.5°). CONCLUSIONS: MBS correlated with Co-Go within sexes and differed significantly between brachyfacial and dolichofacial subjects.

Opinions, plans, and demographics of orthodontic residents: A follow-up study.

INTRODUCTION: This study aimed to explore current orthodontic residents' demographics, their opinions on their residency and plans for the future and highlight secular changes since past surveys. METHODS: An anonymous 39-item institutional review board-approved survey was implemented at the 2018 Graduate Orthodontic Resident Program using an online survey tool and portable devices. Questions fit 3 categories: program, future goals, and demographics. Responses were analyzed to determine frequencies, means, and cross tabulations. Analyses of variance and chi-square were applied with significance defined as P <0.05. RESULTS: Of the 489 attendees, 76% completed the survey; most were female (51%), white (60%), U.S. citizens (85%), single (63%), and very satisfied with their programs (54%). Tuition costs varied, but 18% of respondents paid >$80,000 annually. Orthodontic and total educational debts were significantly correlated (r = 0.704) and averaged $137,706 ± $127,380 and $323,071 ± $266,510, respectively. These debts were significantly lower (P <0.0001) for respondents with stipends. Debts influenced the decision of where to work in the future for 62% of respondents and were a source of anxiety for 72% of respondents. Educational debts were significantly positively associated with anxiety levels (P <0.0001). CONCLUSIONS: This survey provided current information on orthodontic residents' opinions, plans, and demographics. Comparisons with previous surveys showed increases in the number of female respondents, tuition costs, and educational debts and decreases in stipends. Orthodontics may be approaching a "bubble market" where the financial benefits do not outweigh specialty education costs.

3D Slicer Craniomaxillofacial Modules Support Patient-Specific Decision-Making for Personalized Healthcare in Dental Research.

The biggest challenge to improve the diagnosis and therapies of Craniomaxillofacial conditions is to translate algorithms and software developments towards the creation of holistic patient models. A complete picture of the individual patient for treatment planning and personalized healthcare requires a compilation of clinician-friendly algorithms to provide minimally invasive diagnostic techniques with multimodal image integration and analysis. We describe here the implementation of the open-source Craniomaxillofacial module of the 3D Slicer software, as well as its clinical applications. This paper proposes data management approaches for multisource data extraction, registration, visualization, and quantification. These applications integrate medical images with clinical and biological data analytics, user studies, and other heterogeneous data.

Night-time autonomic nervous system ultradian cycling and masticatory muscle activity.

OBJECTIVES: To test if there was a correlation between night-time masticatory muscle activity, as measured by duty factors, and ultradian cycling of autonomic nervous system (ANS) spectral powers in subjects without temporomandibular disorder (TMD)-related pain. SETTING AND SAMPLE POPULATION: The University of Missouri-Kansas City School of Dentistry. Three women and four men of average ages 38 ±8 and 56 ± 17 years, respectively, gave informed consent to participate. MATERIAL AND METHODS: Investigators taught subjects to record heart (electrocardiography, ECG) and masticatory muscle activities (electromyography, EMG). ECG recordings were analysed for ANS ultradian cycling by a polynomial fit to the ratio of sympathetic and parasympathetic spectral powers (ms2 ). Masseter and temporalis EMG recordings were analysed over 20-minute epochs around peaks and valleys in the ANS ultradian cycles. Duty factors (% time of masticatory muscle activity/20-minute epoch) were determined relative to average threshold EMG (TEMG ) required to produce a given bite force (N). Regression analyses quantified relationships between normalized muscle duty factors and ANS spectral powers. RESULTS: Subjects made a total of 27 sets of night-time ECG and EMG recordings that averaged 6.6 ± 1.1 hours per recording. Highest average duty factors were associated with TEMG of 1-2 N and showed cumulative masseter and temporalis activities of 9.2 and 8.8 seconds/20-minute epoch, respectively. Normalized masticatory muscle duty factors showed non-linear relationships with normalized sympathetic (R2  = +0.82), parasympathetic (R2  = -0.70) and sympathetic/parasympathetic spectral powers (R2  = +0.75). CONCLUSIONS: Night-time ANS spectral powers showed ultradian cycling and were correlated with masseter and temporalis muscle activities in adult subjects without TMD.

Expert Consensus on Growth and Development Curricula for Predoctoral and Advanced Education Orthodontic Programs.

Dental students and orthodontic residents must demonstrate competence in various areas prior to graduation. However, the Commission on Dental Accreditation (CODA) definition of competence is broad. The aims of this study were to obtain expert consensus on Growth and Development topics and subtopics in predoctoral and advanced education programs in orthodontics and to determine the level of cognition on the subtopics necessary to demonstrate learner competence. A modified Delphi method with a consensus threshold of 70% was used. In Round One, academic orthodontists who met the expert panel inclusion criteria were surveyed to determine whether a topic was necessary to the curricula. Round Two identified the subtopics under each topic and the level of cognition necessary to demonstrate learner competence using Bloom's taxonomy, which defines the ascending levels of remember, understand, apply, analyze, evaluate, and create. Round Three involved analyses and interpretation of Round Two results. The academic orthodontists determined that six topics (n=24) and 29 subtopics (n=15) were necessary for Growth and Development curricula. For all subtopics, they determined the mean level of cognition for predoctoral education was understand; for advanced education, it was analyze. This consensus on Growth and Development curricular content suggests that these levels are necessary for a beginning dentist and a beginning orthodontist to be deemed competent. Findings from this study can serve to guide curricular development and instruction by using the identified learning objectives to build instructional and assessment measures.

Preface to COAST 2018 Innovators' Workshop: Bridging the biology and technology gap in orthodontics and craniofacial care.

OBJECTIVE: A third focused workshop explored how to transfer novel findings into clinical orthodontic practice. SETTING AND SAMPLE POPULATION: Participants met at the Scottsdale Plaza Resort, 12-16 September 2018 for the Consortium for Orthodontic Advances in Science and Technology 2018 Innovators' Workshop. Thirty speakers and four lunch-hour focus group leaders shared and exchanged information with approximately 45 registered attendees. MATERIAL AND METHODS: This Innovators' Workshop was organized according to five themed sessions which covered: (a) The relevance of genetics, biology and environment to therapeutic outcomes; (b) Application of bioinformatics in craniofacial research; (c) Regeneration with and for orthodontic treatment; (d) Technology in precision orthodontics; and (e) Muscle, joint, and airway: Growth, function and pain. RESULTS: The papers that comprise this supplemental issue exemplify the important outcomes of the 2018 COAST Workshop. In addition, matters identified as important needs include improved understanding of neural, skeletal and muscle tissue crosstalk in early craniofacial growth; standardized methods for three-dimensional radiographic and surface landmark and reference plane identification, measurements and serial superimpositioning techniques for use in the clinic; sharing and making available existing data sets (eg, cone beam computed tomography images, genotype-phenotype data); evidence of the usefulness and effectiveness of new devices; guidelines of what to measure to characterize the airway; more information about the influences of the soft tissues on craniofacial morphology; and information about effective digital work flows applied to clinical and educational settings. CONCLUSIONS: Progress in bridging the biology-technology gap has identified new needs for improvements in orthodontics and craniofacial care.

Psychosocial Scores and Jaw Muscle Activity in Women.

AIMS: To test whether women with temporomandibular disorder (TMD)-related pain showed higher psychosocial scores and higher awake- and sleep-time jaw muscle activities (characterized by duty factors) compared to pain-free controls and whether psychosocial scores and the jaw muscle duty factors were associated. METHODS: Subjects gave informed consent to participate. The Diagnostic Criteria for TMD (DC/TMD) were used for diagnosis of TMD pain, and 31 and 36 women were included in the TMD-related pain and control groups, respectively. DC/TMD Axis II instruments were used to determine psychosocial scores. Subjects self-recorded masseter and anterior temporalis electromyography (EMG) over 3 days and 3 nights. The duty factor (time of muscle activity/total recording time [%]) was quantified using subject-specific EMG/bite-force calibration via data recorded in the laboratory. Group differences (α = .05) were assessed for psychosocial scores and duty factors using chi-square and two-sample t tests. Linear regression assessed whether psychosocial scores were associated with duty factors. RESULTS: Average duty factors were ≤ 2.4% for awake and sleep times in both muscles, and between-group comparisons showed no significant differences. For physical symptom scores, there were significantly fewer TMD-related pain subjects in the normal category and significantly more in the moderate-severe category (all P < .01) compared to controls. Subjects with elevated compared to normal psychosocial scores showed significantly higher jaw muscle duty factors by ≥ 1.5-fold. CONCLUSION: A significantly larger proportion of TMD-related pain subjects compared to control subjects had moderate-severe physical symptom scores. Awake- and sleep-time jaw muscle duty factors were not different between groups and were generally low among all subjects. Additionally, higher than normal psychosocial scores were associated with significantly more low-magnitude jaw muscle activity.

Gender differences in the association of periodontitis and type 2 diabetes.

AIMS: THE OBJECTIVE WAS TO INVESTIGATE IF GENDER DIFFERENCES EXIST IN THE ASSOCIATIONS BETWEEN PERIODONTITIS AND TYPE 2 DIABETES. DISPROPORTIONATE DISPARITIES BY GENDER WERE FOUND TO EXIST IN RATES OF BOTH PERIODONTITIS AND DIABETES WITH RESPECT TO DEMOGRAPHICS AND BEHAVIOURAL PREDICTORS THAT CANNOT BE EXPLAINED SOLELY BY THE WELL-ESTABLISHED ASSOCIATION BETWEEN THESE TWO DISEASES. MATERIALS AND METHODS: MULTIPLE DATASETS WERE EXTRACTED FROM THE NATIONAL HEALTH AND NUTRITION EXAMINATION SURVEY (NHANES) 2009-2014, WHICH USED A STRATIFIED MULTISTAGE PROBABILITY SAMPLING TO OBTAIN SAMPLES FROM ALL CIVILIAN NON-INSTITUTIONALISED PEOPLE IN THE USA. BIVARIATE RELATIONSHIPS BETWEEN EACH EXPLANATORY VARIABLE AND PERIODONTITIS LEVEL WERE ASSESSED WITH ODDS RATIOS (OR) AND THEIR 95% CONFIDENCE INTERVALS (CI). A SET OF WEIGHTED LOGISTIC REGRESSION MODELS WAS USED TO INVESTIGATE THE ASSOCIATION DIFFERENTIATIONS BETWEEN PERIODONTITIS AND DIABETES BY GENDER. C-STATISTICS MEASURED THE GOODNESS-OF-FIT OF WEIGHTED LOGISTIC REGRESSION MODELS. RESULTS: THE PREVALENCE OF MODERATE-SEVERE PERIODONTITIS WAS 36.39% AND 22.71% AMONG PARTICIPANTS WITH TYPE 2 DIABETES AND WITHOUT DIABETES, RESPECTIVELY. TYPE 2 DIABETES WAS SIGNIFICANTLY ASSOCIATED WITH MODERATE-SEVERE PERIODONTITIS OR (OR = 1.47, 95% CI: 1.18-1.82) AMONG MALES EVEN AFTER ADJUSTING FOR DEMOGRAPHICS, SOCIOECONOMIC STATUS AND ORAL HEALTH BEHAVIOURS. THE AFOREMENTIONED RELATIONSHIP WAS NOT FOUND IN FEMALES. FURTHERMORE, DIFFERENT RELATIONSHIPS OF MODERATE-SEVERE PERIODONTITIS WITH BODY MASS INDEX AND THE USE OF MOUTHWASH WERE FOUND BETWEEN THE MALES AND FEMALES. CONCLUSIONS: THE CURRENT FINDINGS SUGGEST THAT IMPORTANT IMPROVEMENTS IN THE DEVELOPMENT OF GENDER-SPECIFIC STRATEGIES IN PREVENTION, SUCH AS ORAL HOME-CARE, TO REDUCE THE HIGH PREVALENCE OF PERIODONTAL DISEASE AND MAINTAIN GOOD ORAL HEALTH ARE VITAL, AND ARE ESPECIALLY IMPORTANT FOR MALE DIABETIC PATIENTS AND THOSE WHO ARE AT HIGH RISK OF DEVELOPING DIABETES, SUCH AS THOSE WHO ARE OBESE.

Disposable aptamer-sensor aided by magnetic nanoparticle enrichment for detection of salivary cortisol variations in obstructive sleep apnea patients.

We report a disposable point-of-care sensing platform specific to salivary cortisol detection. The sensor is inkjet printed on a paper substrate with a metalloporphyrin based macrocyclic catalyst ink that can electrochemically reduce cortisol, captured by aptamer functionalized magnetic nanoparticles. The sensor consists of a thin magnet disc, aligned at the back of the electrode, in order to populate the magnetic nanoparticle bound cortisol at the sensing electrode area. Proof of concept studies were performed to detect salivary cortisol levels in human subjects with high and low risks for obstructive sleep apnea (OSA). High selectivity was observed to salivary cortisol against a background of closely related steroids.

Self-reported health and behavioral factors are associated with metabolic syndrome in Americans aged 40 and over.

To determine whether behavioral factors differ among metabolic conditions and self-reported health, and to determine whether self-reported health is a valid predictor of metabolic syndrome (MetS). A total of 2997 individuals (≥ 40 years old) were selected from four biennial U.S. National Health and Nutrition Examination Surveys (2007-2014). A set of weighted logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs)Individuals with light physical activity are more likely to have MetS and report poor health than those with vigorous physical activity with OR = 3.22 (95% CI: 2.23, 4.66) and 4.52 (95% CI: 2.78, 7.33), respectively. Individuals eating poor diet have greater odds of developing MetS and reporting poor health with OR = 1.32 (95% CI: 1.05, 1.66) and 3.13 (95% CI: 2.46, 3.98). The aforementioned relationships remained significant after adjustment for demographic and socio-economic status. A potential intervention strategy will be needed to encourage individuals to aggressively improve their lifestyle to reduce MetS and improve quality of life. Despite the significant association between self-reported health with MetS, a low sensitivity indicated that better screening tools for MetS, diabetes and cardiovascular disease are essential.

Sex differences in jaw muscle duty factors during exercise in two environments: A pilot study.

It is unknown if females and males use jaw muscles similarly during exercise. This pilot study assessed jaw elevator muscle duty factors (DFs=time of muscle activity/total recording time) at repeated sessions to test if DFs are reliable and different between sexes during exercises in two environments. Ten female and seven male subjects recruited from university soccer teams provided informed consent. Surface electromyography was recorded from masseter and temporalis muscles during biting and leg-extension laboratory exercises. Average activities to produce 20N bite-forces for each muscle and subject determined thresholds (5-80%·T20N) for subject-specific DF calculations during exercises performed in laboratory and natural environments. Subjects self-recorded via portable electromyography equipment during in-field leg-extension and weight-lifting exercises. Effects of variables on DFs were assessed via ANOVA (α=0.05) and simple effects testing (Bonferroni-adjusted p⩽0.012). All subjects used jaw muscles during exercises in both environments. DFs between laboratory sessions were reliable (R=0.84). During laboratory exercises, male temporalis DFs were significantly higher than female DFs from both muscles (p⩽0.001). During in-field exercises females had higher DFs during weight-lifting while males had higher DFs during leg-extensions. In-field sex differences were significant at most thresholds and showed larger effect sizes for leg-extension compared to weight-lifting exercises.

Association of Masseter Muscle Activities during Awake and Sleep Periods with Self-Reported Anxiety, Depression, and Somatic Symptoms.

AIM AND BACKGROUND: The objective of this study was to determine if duty factors (DF) of low-magnitude MMA during awake and sleep periods were associated with self-reports of anxiety, depression, and somatic symptoms, and if so, whether or not any associations were modified by gender or the presence of pain. Limited information is currently available in the literature regarding the association of low-magnitude masseter muscle activities (MMA) in habitual environmental settings and the presence of psychological symptoms. MATERIALS AND METHODS: Sixty-eight consenting participants were classified using the Diagnostic Criteria for Temporomandibular Disorders examination and validated self-reporting psychological symptom evaluation questionnaires. Each subject also had masseter electromyography recordings during standardized biting tasks in 2 laboratory sessions to calibrate the in-field MMA collected during 3 awake and 3 sleep periods. RESULTS: During awake periods, subjects with self-reported depression and somatic symptoms had statistically high odds of having higher DF of low-magnitude MMA (defined by ≥ 75th percentile of sample). The association between high DF of low-magnitude MMA and self-reported depression symptoms was significantly augmented among male participants, whereas, the association between high DF of low-magnitude MMA and self-reported somatic symptoms was significantly increased among female participants without pain. CONCLUSION: These pilot data support associations of low-magnitude masseter muscle activities with self-reported depression and somatic symptoms during awake periods.

Effects of mechanical stress and growth on the velocity of tooth movement.

INTRODUCTION: In this study, we investigated the effects of the magnitudes of applied stress and growth status on the speed of tooth movement. METHODS: Eighty-two maxillary canines in 41 subjects were retracted for 84 days by estimated stresses of 4, 13, 26, 52, or 78 kPa applied continuously via segmental mechanics. Dental impressions made at intervals of 1 to 14 days resulted in 9 or 10 dental casts per subject. Three-dimensional tooth movements were quantified using these casts, custom reference templates, and a measuring microscope. Serial height and cephalometric measurements determined growth status. RESULTS: Distal tooth movement was linear with no lag phase in 96% of the teeth. Speeds averaged 0.028, 0.040, 0.050, 0.054, and 0.061 mm per day (standard errors, ± 0.004) for 4, 13, 26, 52, and 78 kPa, respectively. The maximum difference in speed between teeth was 9:1. Teeth moved significantly faster (P <0.0001) in growing compared with nongrowing subjects, on average by 1.6-fold. Stress and speed of tooth movement were logarithmically related in growing (R(2) = 0.47) and nongrowing (R(2) = 0.34) subjects. Other tooth movements were relatively small, except for the distopalatal rotation of teeth moved by 78 kPa that averaged more than 19°. CONCLUSIONS: The speed of retraction was logarithmically related to the applied stress and was significantly faster in actively growing subjects compared with those who were not growing.