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Wu Y, Cisewski SE, Coombs MC, Brown MH, Wei F, She X, Kern MJ, Gonzalez YM, Gallo LM, Colombo V, Iwasaki LR, Nickel JC, Yao H. Effect of Sustained Joint Loading on TMJ Disc Nutrient Environment. J Dent Res 2019; 98:888-895. [PMID: 31126205 DOI: 10.1177/0022034519851044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The temporomandibular joint (TMJ) disc nutrient environment profoundly affects cell energy metabolism, proliferation, and biosynthesis. Due to technical challenges of in vivo measurements, the human TMJ disc extracellular nutrient environment under load, which depends on metabolic rates, solute diffusion, and disc morphometry, remains unknown. Therefore, the study objective was to predict the TMJ disc nutrient environment under loading conditions using combined experimental and computational modeling approaches. Specifically, glucose consumption and lactate production rates of porcine TMJ discs were measured under varying tissue culture conditions (n = 40 discs), and mechanical strain-dependent glucose and lactate diffusivities were measured using a custom diffusion chamber (n = 6 discs). TMJ anatomy and loading area were obtained from magnetic resonance imaging of healthy human volunteers (n = 11, male, 30 ± 9 y). Using experimentally determined nutrient metabolic rates, solute diffusivities, TMJ anatomy, and loading areas, subject-specific finite element (FE) models were developed to predict the 3-dimensional nutrient profiles in unloaded and loaded TMJ discs (unloaded, 0% strain, 20% strain). From the FE models, glucose, lactate, and oxygen concentration ranges for unloaded healthy human TMJ discs were 0.6 to 4.0 mM, 0.9 to 5.0 mM, and 0% to 6%, respectively, with steep gradients in the anterior and posterior bands. Sustained mechanical loading significantly reduced nutrient levels (P < 0.001), with a critical zone in which cells may die representing approximately 13.5% of the total disc volume. In conclusion, this study experimentally determined TMJ disc metabolic rates, solute diffusivities, and disc morphometry, and through subject-specific FE modeling, revealed critical interactions between mechanical loading and nutrient supply and metabolism for the in vivo human TMJ disc. The results suggest that TMJ disc homeostasis may be vulnerable to pathological loading (e.g., clenching, bruxism), which impedes nutrient supply. Given difficulties associated with direct in vivo measurements, this study provides a new approach to systematically investigate homeostatic and degenerative mechanisms associated with the TMJ disc.
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Affiliation(s)
- Y Wu
- 1 Department of Bioengineering, Clemson University, Clemson, SC, USA.,2 Department of Orthopaedics and Physical Medicine, Medical University of South Carolina (MUSC), Charleston, SC, USA
| | - S E Cisewski
- 1 Department of Bioengineering, Clemson University, Clemson, SC, USA.,3 Department of Oral Health Sciences, College of Dental Medicine, MUSC, Charleston, SC, USA
| | - M C Coombs
- 1 Department of Bioengineering, Clemson University, Clemson, SC, USA.,3 Department of Oral Health Sciences, College of Dental Medicine, MUSC, Charleston, SC, USA
| | - M H Brown
- 3 Department of Oral Health Sciences, College of Dental Medicine, MUSC, Charleston, SC, USA
| | - F Wei
- 1 Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - X She
- 1 Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - M J Kern
- 3 Department of Oral Health Sciences, College of Dental Medicine, MUSC, Charleston, SC, USA
| | - Y M Gonzalez
- 4 Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - L M Gallo
- 5 Clinic of Masticatory Disorders, University of Zurich, School of Dental Medicine, Zurich, Switzerland
| | - V Colombo
- 5 Clinic of Masticatory Disorders, University of Zurich, School of Dental Medicine, Zurich, Switzerland
| | - L R Iwasaki
- 6 Department of Orthodontics, School of Dentistry, Oregon Health & Science University, Portland, OR, USA
| | - J C Nickel
- 6 Department of Orthodontics, School of Dentistry, Oregon Health & Science University, Portland, OR, USA
| | - H Yao
- 1 Department of Bioengineering, Clemson University, Clemson, SC, USA.,2 Department of Orthopaedics and Physical Medicine, Medical University of South Carolina (MUSC), Charleston, SC, USA.,3 Department of Oral Health Sciences, College of Dental Medicine, MUSC, Charleston, SC, USA
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Abstract
Craniofacial secondary cartilages of the mandibular condyle and temporomandibular joint (TMJ) eminence grow in response to the local mechanical environment. The intervening TMJ disc distributes normal loads over the cartilage surfaces and provides lubrication. A better understanding of the mechanical environment and its effects on growth, development, and degeneration of the TMJ may improve treatments aimed at modifying jaw growth and preventing or reversing degenerative joint disease (DJD). This review highlights data recorded in human subjects and from computer modeling that elucidate the role of mechanics in TMJ ontogeny. Presented data provide an approximation of the age-related changes in jaw-loading behaviors and TMJ contact mechanics. The cells of the mandibular condyle, eminence, and disc respond to the mechanical environment associated with behaviors and ultimately determine the TMJ components' mature morphologies and susceptibility to precocious development of DJD compared to postcranial joints. The TMJ disc may be especially prone to degenerative change due to its avascularity and steep oxygen and glucose gradients consequent to high cell density and rate of nutrient consumption, as well as low solute diffusivities. The combined effects of strain-related hypoxia and limited glucose concentrations dramatically affect synthesis of the extracellular matrix (ECM), which limit repair capabilities. Magnitude and frequency of jaw loading influence this localized in situ environment, including stem and fibrocartilage cell chemistry, as well as the rate of ECM mechanical fatigue. Key in vivo measurements to characterize the mechanical environment include the concentration of work input to articulating tissues, known as energy density, and the percentage of time that muscles are used to load the jaws out of a total recording time, known as duty factor. Combining these measurements into a mechanobehavioral score and linking these to results of computer models of strain-regulated biochemical events may elucidate the mechanisms responsible for growth, maintenance, and deterioration of TMJ tissues.
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Affiliation(s)
- J C Nickel
- 1 Department of Orthodontics, School of Dentistry, Oregon Health & Science University, Portland, OR, USA.,2 Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - L R Iwasaki
- 1 Department of Orthodontics, School of Dentistry, Oregon Health & Science University, Portland, OR, USA.,2 Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - Y M Gonzalez
- 2 Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - L M Gallo
- 3 Department of Masticatory Disorders, University of Zurich School of Dental Medicine, Zurich, Switzerland
| | - H Yao
- 4 Department of Bioengineering, Clemson University, Clemson, SC, USA.,5 Department of Oral Health Sciences, College of Dental Medicine, Medical University of South Carolina, Charleston, SC, USA
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Abstract
OBJECTIVES To test whether mechanobehaviour (temporomandibular joint (TMJ) loads, jaw muscle use) was different between facial types and correlated with ramus height (Condylion-Gonion, mm). SETTING AND SAMPLE POPULATION University of Missouri-Kansas City (UMKC) Orthodontic Clinic. Ten dolichofacial and ten brachyfacial adolescents (Sella-Nasion-Gonion-Gnathion (SN-GoGn) angles ≥37° and ≤27°, respectively) consented to participate. MATERIALS AND METHODS Numerical models calculated TMJ loads for a range of static biting based on subjects' three-dimensional anatomy. Subjects were trained to record jaw muscle electromyography (EMG) over 2 days and 2 nights in their natural environments. Laboratory EMG/bite-force calibrations determined subject-specific EMG for 20 N bite-force (T20Nave ). Jaw muscle use via duty factors (DF=muscle activity duration/total recording time, %) was determined from day and night recordings for muscle-specific thresholds from ≥5% to ≥80%T20Nave . ANOVA and Tukey's HSD post hoc tests assessed for group differences in mechanobehaviour (TMJ loads, DFs). Regression modelling correlated subjects' normalized TMJ loads, DFs and ramus height. RESULTS Dolichofacial compared to brachyfacial subjects produced significantly higher (P<.05) TMJ loads, where ipsilateral loads were ≥20% larger for some biting angles, but had significantly less (all P<.05) masseter (day, night) and temporalis (night) DFs. Regression analysis showed a significant relationship amongst normalized TMJ loads, masseter DF and ramus height (R2 =.49). CONCLUSIONS Mechanobehaviour showed significant differences between facial types and was correlated with ramus height.
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Affiliation(s)
- J C Nickel
- Department of Orthodontics and Dentofacial Orthopedics, University of Missouri-Kansas City, Kansas City, MO, USA.,Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
| | - A L Weber
- Private Practice, Kansas City, MO, USA
| | | | - Y Liu
- Department of Biostatistics and Epidemiology, East Tennessee State University, Johnson City, TN, USA
| | - H Liu
- Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
| | - L R Iwasaki
- Department of Orthodontics and Dentofacial Orthopedics, University of Missouri-Kansas City, Kansas City, MO, USA.,Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
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Wu Y, Cisewski SE, Wei F, She X, Gonzales TS, Iwasaki LR, Nickel JC, Yao H. Fluid pressurization and tractional forces during TMJ disc loading: A biphasic finite element analysis. Orthod Craniofac Res 2018. [PMID: 28643926 DOI: 10.1111/ocr.12147] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To investigate the ploughing mechanism associated with tractional force formation on the temporomandibular joint (TMJ) disc surface. SETTING AND SAMPLE POPULATION Ten left TMJ discs were harvested from 6- to 8-month-old male Yorkshire pigs. MATERIALS AND METHODS Confined compression tests characterized mechanical TMJ disc properties, which were incorporated into a biphasic finite element model (FEM). The FEM was established to investigate load carriage within the extracellular matrix (ECM) and the ploughing mechanism during tractional force formation by simulating previous in vitro plough experiments. RESULTS Biphasic mechanical properties were determined in five TMJ disc regions (average±standard deviation for aggregate modulus: 0.077±0.040 MPa; hydraulic permeability: 0.88±0.37×10-3 mm4 /Ns). FE simulation results demonstrated that interstitial fluid pressurization is a dominant loading support mechanism in the TMJ disc. Increased contact load and duration led to increased solid ECM strain and stress within, and increased ploughing force on the surface of the disc. CONCLUSION Sustained mechanical loading may play a role in load carriage within the ECM and ploughing force formation during stress-field translation at the condyle-disc interface. This study further elucidated the mechanism of ploughing on tractional force formation and provided a baseline for future analysis of TMJ mechanics, cartilage fatigue and early TMJ degeneration.
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Affiliation(s)
- Y Wu
- Department of Bioengineering, Clemson University, Clemson, SC, USA.,Department of Orthopaedics, Medical University of South Carolina (MUSC), Charleston, SC, USA
| | - S E Cisewski
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - F Wei
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - X She
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - T S Gonzales
- Department of Oral Health Sciences, MUSC, Charleston, SC, USA
| | - L R Iwasaki
- Department of Orthodontics and Dentofacial Orthopaedics, University of Missouri-Kansas City, Kansas City, MO, USA
| | - J C Nickel
- Department of Orthodontics and Dentofacial Orthopaedics, University of Missouri-Kansas City, Kansas City, MO, USA
| | - H Yao
- Department of Bioengineering, Clemson University, Clemson, SC, USA.,Department of Orthopaedics, Medical University of South Carolina (MUSC), Charleston, SC, USA.,Department of Oral Health Sciences, MUSC, Charleston, SC, USA
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Gallo LM, Fankhauser N, Gonzalez YM, Liu H, Liu Y, Nickel JC, Iwasaki LR. Jaw closing movement and sex differences in temporomandibular joint energy densities. J Oral Rehabil 2018; 45:97-103. [PMID: 29164651 PMCID: PMC5799013 DOI: 10.1111/joor.12588] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2017] [Indexed: 01/22/2023]
Abstract
Energy densities (ED, mJ/mm3 ) quantify mechanical work imposed on articular cartilages during function. This cross-sectional study examined differences in temporomandibular joint (TMJ) ED during asymmetric versus symmetric jaw closing in healthy females versus males. ED component variables were tested for differences between and within sexes for two types of jaw closing. Seventeen female and 17 male subjects gave informed consent to participate. Diagnostic criteria for temporomandibular disorders and images (magnetic resonance (MR), computed tomography) were used to confirm healthy TMJ status. Numerical modelling predicted TMJ loads (Fnormal ) consequent to unilateral canine biting. Dynamic stereometry combined MR imaging and jaw-tracking data to measure ED component variables during 10 trials of each type of jaw closing in each subject's TMJs. These data were then used to calculate TMJ ED during jaw closing asymmetrically and symmetrically. Paired and Student's t tests assessed ED between jaw closing movements and sexes, respectively. Multivariate data analyses assessed ED component variable differences between jaw closing movements and sexes (α = 0.05). Contralateral TMJ ED were 3.6-fold and significantly larger (P < .0001) during asymmetric versus symmetric jaw closing, due to significantly larger (P ≤ .001) distances of TMJ stress-field translation in asymmetric versus symmetric movement. During asymmetric jaw closing, contralateral TMJ ED were twofold and significantly larger (P = .036) in females versus males, due to 1.5-fold and significantly smaller (P ≤ .010) TMJ disc cartilage volumes under stress fields in females versus males. These results suggest that in healthy individuals, asymmetric compared to symmetric jaw closure in females compared to males has higher TMJ mechanical fatigue liabilities.
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Affiliation(s)
- L M Gallo
- Department of Masticatory Disorders, School of Dental Medicine, University of Zurich, Zurich, Switzerland
| | - N Fankhauser
- Department of Masticatory Disorders, School of Dental Medicine, University of Zurich, Zurich, Switzerland
| | - Y M Gonzalez
- Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - H Liu
- Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Y Liu
- Department of Biostatistics & Epidemiology, East Tennessee State University, Johnson City, TN, USA
| | - J C Nickel
- Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - L R Iwasaki
- Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
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Abstract
OBJECTIVES To test that the speed of tooth translation is not affected by stress magnitude and growth status. SETTING AND SAMPLE POPULATION Advanced Education Orthodontic clinics at the Universities of Nebraska Medical Center and Missouri-Kansas City. Forty-six consenting subjects with orthodontic treatment plans involving maxillary first premolar extractions. MATERIALS AND METHODS This randomized split-mouth study used segmental mechanics with definitive posterior anchorage and individual vertical-loop maxillary canine retraction appliances and measured three-dimensional tooth movements. Height and cephalometric superimposition changes determined growing (G) and non-growing (NG) subjects. Subjects were appointed for 9-11 visits over 84 days for maxillary dental impressions to measure three-dimensional tooth movement and to ensure retraction forces were continuously applied via calibrated nitinol coil springs. Springs were custom selected to apply two different stresses of 4, 13, 26, 52 or 78 kPa to maxillary canines in each subject. Statistical analyses (α=0.050) included ANOVA, effect size (partial η2 ) and Tukey's Honest Significant Difference (HSD) and two-group t tests. RESULTS Distolateral translation speeds were 0.034±0.015, 0.047±0.019, 0.066±0.025, 0.068±0.016 and 0.079±0.030 mm/d for 4, 13, 26, 52 and 78 kPa, respectively. Stress significantly affected speed and partial η2 =0.376. Overall, more distopalatal rotation was shown by teeth moved by 78 kPa (18.03±9.50º) compared to other stresses (3.86±6.83º), and speeds were significantly higher (P=.001) in G (0.062±0.026 mm/d) than NG subjects (0.041±0.019 mm/d). CONCLUSIONS Stress magnitude and growth status significantly affected the speed of tooth translation. Optimal applied stresses were 26-52 kPa, and overall speeds were 1.5-fold faster in G compared to NG subjects.
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Affiliation(s)
- L R Iwasaki
- Department of Orthodontics and Dentofacial Orthopedics, University of Missouri-Kansas City, Kansas City, MO, USA.,Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Y Liu
- Department of Biostatistics and Epidemiology, East Tennessee State University, Johnson City, TN, USA
| | - H Liu
- Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
| | - J C Nickel
- Department of Orthodontics and Dentofacial Orthopedics, University of Missouri-Kansas City, Kansas City, MO, USA.,Department of Oral and Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
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Nickel JC, Covell DA, Frazier-Bowers SA, Kapila S, Huja SS, Iwasaki LR. Preface to COAST 2016 innovators’ workshop on personalized and precision orthodontic therapy. Orthod Craniofac Res 2017. [DOI: 10.1111/ocr.12173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- J. C. Nickel
- School of Dentistry; Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences; University of Missouri-Kansas City; Kansas City MO USA
| | - D. A. Covell
- School of Dentistry; Department of Orthodontics; Oregon Health and Science University; Portland OR USA
| | - S. A. Frazier-Bowers
- School of Dentistry; Department of Orthodontics; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - S. Kapila
- Division of Orthodontics; University of California San Francisco; San Francisco CA USA
| | - S. S. Huja
- College of Dentistry, Department of Oral Health Science; University of Kentucky; Lexington KY USA
| | - L. R. Iwasaki
- School of Dentistry; Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences; University of Missouri-Kansas City; Kansas City MO USA
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Iwasaki LR, Liu Y, Liu H, Nickel JC. Jaw mechanics in dolichofacial and brachyfacial phenotypes: A longitudinal cephalometric-based study. Orthod Craniofac Res 2017. [DOI: 10.1111/ocr.12174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- L. R. Iwasaki
- Department of Orthodontics and Dentofacial Orthopedics; University of Missouri-Kansas City; Kansas MO USA
- Department of Oral and Craniofacial Sciences; University of Missouri-Kansas City; Kansas MO USA
| | - Y. Liu
- Department of Biostatistics and Epidemiology; East Tennessee State University; Johnson City TN USA
| | - H. Liu
- Department of Oral and Craniofacial Sciences; University of Missouri-Kansas City; Kansas MO USA
| | - J. C. Nickel
- Department of Orthodontics and Dentofacial Orthopedics; University of Missouri-Kansas City; Kansas MO USA
- Department of Oral and Craniofacial Sciences; University of Missouri-Kansas City; Kansas MO USA
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Iwasaki LR, Gonzalez YM, Liu Y, Liu H, Markova M, Gallo LM, Nickel JC. TMJ energy densities in healthy men and women. Osteoarthritis Cartilage 2017; 25:846-849. [PMID: 28064032 PMCID: PMC5438898 DOI: 10.1016/j.joca.2016.12.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 12/24/2016] [Accepted: 12/29/2016] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Cartilage fatigue, due to mechanical work, may account for the early development of degenerative joint disease (DJD) in the temporomandibular joint (TMJ), and why women are three times more likely to be afflicted. This study tested for gender differences in mechanical energy densities in women and men with healthy TMJs. DESIGN Eighteen women and eighteen men gave informed consent. Research diagnostic criteria including imaging were used to ensure that subjects' TMJs were normal, without disc displacement or signs of DJD. Numerical modeling determined TMJ loads (Fnormal). Jaw tracking and three-dimensional dynamic stereometry characterized individual-specific data of stress-field dynamic mechanics during 10 symmetrical jaw closing cycles. These data were used to estimate tractional forces (Ftraction). Energy densities were then calculated, where: Energy Density = W/Q (W = work done or mechanical energy input = Ftraction*distance of stress-field translation, Q = volume of cartilage). Two-way analysis of variance (ANOVA) and follow-up two-group comparisons tested mean energy densities for ipsilateral and contralateral TMJs in women vs men. RESULTS Mean energy densities ± standard deviations in ipsilateral and contralateral TMJs in women were 9.0 ± 9.7 and 8.4 ± 5.5 mJ/mm3, respectively, and were significantly larger (P = 0.004 and 0.001, respectively) compared to ipsilateral and contralateral TMJs in men, which were 5.6 ± 4.2 and 6.3 ± 4.2 mJ/mm3, respectively. CONCLUSIONS Energy densities were significantly larger in healthy TMJs of women than men. Larger TMJ energy densities during normal jaw functions could predispose earlier mechanical fatigue of the TMJ disc.
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Affiliation(s)
- L R Iwasaki
- University of Missouri-Kansas City, School of Dentistry, Department of Orthodontics & Dentofacial Orthopedics, USA; University of Missouri-Kansas City, School of Dentistry, Department of Oral & Craniofacial Sciences, USA.
| | - Y M Gonzalez
- University at Buffalo, School of Dental Medicine, Department of Oral Diagnostic Sciences, USA.
| | - Y Liu
- East Tennessee State University, Department of Biostatistics & Epidemiology, USA.
| | - H Liu
- University of Missouri-Kansas City, School of Dentistry, Department of Oral & Craniofacial Sciences, USA.
| | - M Markova
- University of Zurich, Center for Dental & Oral Medicine & Oral Maxillofacial Surgery, Clinic for Masticatory Disorders, Switzerland.
| | - L M Gallo
- University of Zurich, Center for Dental & Oral Medicine & Oral Maxillofacial Surgery, Clinic for Masticatory Disorders, Switzerland.
| | - J C Nickel
- University of Missouri-Kansas City, School of Dentistry, Department of Orthodontics & Dentofacial Orthopedics, USA; University of Missouri-Kansas City, School of Dentistry, Department of Oral & Craniofacial Sciences, USA
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Wei F, Van Horn MH, Coombs MC, She X, Gonzales TS, Gonzalez YM, Scott JM, Iwasaki LR, Nickel JC, Yao H. A pilot study of nocturnal temporalis muscle activity in TMD diagnostic groups of women. J Oral Rehabil 2017; 44:517-525. [PMID: 28449265 DOI: 10.1111/joor.12517] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2017] [Indexed: 01/28/2023]
Abstract
Temporomandibular disorder (TMD) incidences are believed to be related to parafunctional behaviours like teeth clenching. This pilot study aimed to (i) develop an automated clench-detection algorithm, and (ii) apply the algorithm to test for differences in nocturnal clenching in women with and without TMD. Subjects gave informed consent to participate. Adult women were categorised using Diagnostic Criteria for TMD according to presence/absence (+/-) of both TM joint disc placement (DD) and chronic pain (P) into two groups (+DD+P, -DD-P) with 12 subjects each. Surface temporalis electromyography was recorded during oral tasks performed by subjects at two laboratory sessions. The data were used to characterise muscle activity per N of bite force (μV/N) for each subject, develop the clench-detection algorithm and test its accuracy. Ambulatory surface temporalis electromyography was self-recorded by each subject over three nights and analysed using the algorithm and bite force (N) versus muscle activity μV/N calibrations. Bonferroni-adjusted homoscedastic t-tests assessed for significant between-group differences in clenching (P < 0·05). Sensitivity, specificity and accuracy of algorithm-detected laboratory clenches were all ≥96%. During self-recordings 95% of clenches had durations of <4 s and peak forces of <10 N in both groups. Mean clench durations were significantly longer (P = 0·042) in +DD+P (1·9 ± 0·8 s) than -DD-P subjects (1·4 ± 0·4 s). Mean temporalis duty factors (%clench time/total recording time) were significantly larger (P = 0·041) in +DD+P (0·47 ± 0·34%) than -DD-P (0·26 ±0·22%) subjects. Nocturnal temporalis muscle activities detected by a validated algorithm were longer per clench and recording time in +DD+P compared to -DD-P women.
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Affiliation(s)
- F Wei
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - M H Van Horn
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - M C Coombs
- Department of Bioengineering, Clemson University, Clemson, SC, USA.,Department of Oral Health Sciences, College of Dental Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - X She
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - T S Gonzales
- Department of Oral Health Sciences, College of Dental Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Y M Gonzalez
- Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - J M Scott
- Department of Research and Graduate Programs, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - L R Iwasaki
- Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA.,Departments of Orthodontics and Dentofacial Orthopedics, and Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - J C Nickel
- Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA.,Departments of Orthodontics and Dentofacial Orthopedics, and Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - H Yao
- Department of Bioengineering, Clemson University, Clemson, SC, USA.,Department of Oral Health Sciences, College of Dental Medicine, Medical University of South Carolina, Charleston, SC, USA
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Abstract
The etiology of degenerative disease of the TMJ may involve fatigue produced by surface tractional forces and compressive stresses. This study tested the time-dependent effects of compressive loading and stress-field translation on TMJ disc-surface tractional forces and stresses. In laboratory experiments with 50 porcine discs, an acrylic indenter imposed 10 N static loads for 10 and 60 sec, followed by translation of the loaded indenter along the mediolateral axis of the disc. Maximum tractional forces were found to occur following 60 sec of static loading (p < 0.001), and increased with translation velocity (R2 = 0.73); whereas maximum compressive stresses occurred after 10 sec of static loading (p < 0.001). Overall, the results were consistent with current mechanical theories of the time-dependent effects of compressive loading of cartilage.
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Affiliation(s)
- J C Nickel
- University of Nebraska Medical Center College of Dentistry, Department of Growth and Development, Lincoln, 68583-0755, USA.
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12
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Iwasaki LR, Covell DA, Frazier-Bowers SA, Kapila S, Huja SS, Nickel JC. Personalized and precision orthodontic therapy. Orthod Craniofac Res 2016; 18 Suppl 1:1-7. [PMID: 25865528 DOI: 10.1111/ocr.12089] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2015] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To bring together orthodontic stakeholders from academics, industry, and private practice for a series of thematically focused workshops to explore and develop the transfer of novel approaches into clinical orthodontic practice. SETTING AND SAMPLE POPULATION Twenty-seven invited speakers, eight poster presenters, and participants of the Consortium for Orthodontic Advances in Science and Technology (COAST) 2014 Innovators' Workshop at the Eaglewood Resort and Spa, Itasca, Illinois, September 11-14, 2014. MATERIAL AND METHODS Five themed sessions involving between 4-7 presentations followed by panel discussions were organized. The aims of the discussion sessions were to highlight important findings and consider the strength of evidence for these, indicate next steps and needed research or technological developments to move forward, and to weigh the expected benefits from these findings and steps to implement in clinical practice. RESULTS Among important areas for attention identified were need for multiscale and multispecies modeling and experimentation for interspecies translation of results; large-scale collaborative efforts within the profession to address the need for adequate sample sizes for future genetic studies of complex traits such as malocclusion; a consortium approach to improve new technologies such as intra-oral scanning and 3D imaging by establishing standards; and harnessing the growing body of knowledge about bone biology for application in orthodontics. CONCLUSIONS With increased awareness of the potential of current and emerging technologies, translation of personalized and precision approaches in the field of orthodontics holds ever-increasing promise.
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Affiliation(s)
- L R Iwasaki
- School of Dentistry, Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
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Khawaja SN, McCall W, Dunford R, Nickel JC, Iwasaki LR, Crow HC, Gonzalez Y. Infield masticatory muscle activity in subjects with pain-related temporomandibular disorders diagnoses. Orthod Craniofac Res 2016; 18 Suppl 1:137-45. [PMID: 25865542 DOI: 10.1111/ocr.12077] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2014] [Indexed: 01/11/2023]
Abstract
OBJECTIVES Pain-related temporomandibular disorders (TMDs) are the most prevalent conditions among TMDs. There is contrasting evidence available for association of pain-related TMD and masticatory muscle activity (MMA). The present investigation assesses the associations between MMA levels of masseter and temporalis muscles during awake and sleep among pain-related TMD diagnostic groups. SETTING AND SAMPLE POPULATION The department of Oral Diagnostic Sciences, University at Buffalo. Twenty females and six males participated in this study. MATERIAL AND METHODS Using the diagnostic criteria for temporomandibular disorders (DC-TMDs), participants were diagnostically categorized. Subjects used a custom monitoring system, which recorded infield muscle activities. A factorial model tested for association between independent variable (muscle, time period, MMA level, and diagnostic group) effects and the logarithm of MMA. Greenhouse-Geisser test was used to determine any statistically significant associations (p≤0.003). RESULTS No statistically significant association was found between four-way, three-way, and two-way analyses. However, among the main effects, range of magnitudes was the only variable to be statistically significant. Although the data suggest a trend of increased masseter MMA in the pain-related TMD diagnoses group both during awake and sleep time periods, such observation is not maintained for the temporalis muscle. In addition, temporalis MMA was found to be higher in the pain-related TMD diagnoses group only at extreme activity levels (<25 and ≥80% ranges). CONCLUSION This data support the association between masticatory muscle hyperactivity and painful TMD conditions.
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Affiliation(s)
- S N Khawaja
- Oral Diagnostic Sciences, University at Buffalo, Buffalo, NY, USA
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Khawaja SN, Nickel JC, Iwasaki LR, Crow HC, Gonzalez Y. Association between waking-state oral parafunctional behaviours and bio-psychosocial characteristics. J Oral Rehabil 2015; 42:651-6. [PMID: 25891146 DOI: 10.1111/joor.12302] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2015] [Indexed: 12/26/2022]
Abstract
The term 'oral parafunctional behaviours' encompasses behaviours that are different from those required for, or associated with, physiological functional needs such as mastication, communication, swallowing or breathing. Previous reports have associated waking-state oral parafunctional behaviours with biopsychosocial characteristics such as female gender, presence of psychological symptoms, intensity of pain and pain-related temporomandibular disorders (TMD) diagnosis. However, the findings have been inconsistent, possibly due to methodological limitations and differences. In the present investigation, we aim to determine whether any association is present between waking-state oral parafunctional behaviours and biopsychosocial characteristics. All participants were investigated using a set of standardised and validated self-reporting questionnaires and diagnostic criteria for temporomandibular disorders (DC/TMD) examination protocol for clinical characterisation. Univariate analysis found that self-reported waking-state oral parafunctional behaviours were statistically significantly associated with presence of anxiety, depression and physical symptoms, pain intensity and TMD diagnosis. However, forward model multiple linear regression analysis indicated that only self-reported presence of physical and depression symptoms could explain statistically significant portions of the variance in self-reported waking-state oral parafunctional behaviours.
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Affiliation(s)
- S N Khawaja
- Oral Diagnostic Sciences, University at Buffalo, Buffalo, NY, USA
| | - J C Nickel
- Department of Orthodontics and Dentofacial Orthopedics, University of Missouri - Kansas City, Kansas City, MO, USA.,Department of Oral Craniofacial Sciences, University of Missouri - Kansas City, Kansas City, MO, USA
| | - L R Iwasaki
- Department of Orthodontics and Dentofacial Orthopedics, University of Missouri - Kansas City, Kansas City, MO, USA.,Department of Oral Craniofacial Sciences, University of Missouri - Kansas City, Kansas City, MO, USA
| | - H C Crow
- Oral Diagnostic Sciences, University at Buffalo, Buffalo, NY, USA
| | - Y Gonzalez
- Oral Diagnostic Sciences, University at Buffalo, Buffalo, NY, USA
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Iwasaki LR, Liu H, Gonzalez YM, Marx DB, Nickel JC. Modeling of muscle forces in humans with and without temporomandibular joint disorders. Orthod Craniofac Res 2015; 18 Suppl 1:170-9. [PMID: 25865546 DOI: 10.1111/ocr.12075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Subjects with/without temporomandibular joint disorders (TMJD) were tested for differences in muscle forces. SETTING AND SAMPLE POPULATION School of Dental Medicine, University at Buffalo. Ninety-one subjects were classified in four groups based on the presence/absence (±) of chronic myofascial and/or TMJ pain (P) and bilateral disc displacement (DD). MATERIAL AND METHODS Validated numerical models employed an organizational objective and subjects' anatomy to calculate masticatory muscle forces during static biting. anova and Holm's step-down procedure post hoc tests assessed group differences. Theoretical geometries, representing the range of subjects' muscle orientations, were surveyed via numerical models to identify key combinations resulting in high muscle forces. Effect size (Cohen's d) and anova/post hoc tests assessed group differences in key muscle orientations. RESULTS +P-DD subjects had significantly higher muscle forces, especially for lateral pterygoid muscles, compared to the other groups (p<0.01) for bite forces that were directed posteromedially or posterolaterally on mandibular molars and posteriorly and slightly medially on mandibular incisors. Key muscle orientations for peak lateral pterygoid muscle forces were identified, and group comparisons showed mean orientation in +P-DD compared to other diagnostic groups was ≥5° more upright for masseter and ≥3° more posteriorly directed for temporalis muscles (all Cohen's d≥0.8). CONCLUSION Predicted lateral pterygoid muscle forces were significantly higher in +P-DD compared to other groups for specific biting conditions and were attributable, in part, to differences in masseter and temporalis muscle orientations.
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Affiliation(s)
- L R Iwasaki
- Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
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Iwasaki LR, Gonzalez YM, Liu H, Marx DB, Gallo LM, Nickel JC. A pilot study of ambulatory masticatory muscle activities in temporomandibular joint disorders diagnostic groups. Orthod Craniofac Res 2015; 18 Suppl 1:146-55. [PMID: 25865543 PMCID: PMC4396707 DOI: 10.1111/ocr.12085] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2014] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine differences in masticatory muscle usage between temporomandibular joint disorders diagnostic groups. SETTING AND SAMPLE POPULATION Seventy-one informed and consented subjects (27 men; 44 women) participated at the University at Buffalo. MATERIAL AND METHODS Research diagnostic criteria and imaging data were used to categorize subjects according to the presence/absence +/- of TMJ disc placement (DD) and chronic pain (P) (+DD+P, n=18; +DD-P, n=14; -DD-P, n=39). Electromyographic (EMG)/bite-force calibrations determined subject-specific masseter and temporalis muscle activities per 20 N bite-force (T20N , μV). Over 3 days and nights, subjects collected EMG recordings. Duty factors (DFs, % of recording time) were determined based on threshold intervals (5-9, 10-24, 25-49, 50-79, ≥80% T20N ). anova and Tukey-Kramer post hoc tests identified 1) diagnostic group differences in T20N and 2) the effects of diagnostic group, gender, time and interval on muscle DFs. RESULTS Mean (±SE) temporalis T20N in +DD+P subjects was significantly higher (71.4±8.8 μV) than masseter T20N in these subjects (19.6±8.8 μV; p=0.001) and in -DD-P subjects (25.3±6.0 μV, p=0.0007). Masseter DFs at 5-9% T20N were significantly higher in +DD-P women (3.48%) than +DD-P men (0.85%) and women and men in both other diagnostic groups (all p<0.03), and in +DD+P women (2.00%) compared to -DD-P men (0.83%; p=0.029). Night-time DFs at 5-9% T20N in +DD-P women (1.97%) were significantly higher than in -DD-P men (0.47%) and women (0.24%; all p<0.01). CONCLUSIONS Between-group differences were found in masticatory muscle activities in both laboratory and natural environmental settings.
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Affiliation(s)
- L R Iwasaki
- Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
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Gallo LM, Iwasaki LR, Gonzalez YM, Liu H, Marx DB, Nickel JC. Diagnostic group differences in temporomandibular joint energy densities. Orthod Craniofac Res 2015; 18 Suppl 1:164-9. [PMID: 25865545 PMCID: PMC4396680 DOI: 10.1111/ocr.12074] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Cartilage fatigue, due to mechanical work, may account for precocious development of degenerative joint disease in the temporomandibular joint (TMJ). This study compared energy densities (mJ/mm³) in TMJs of three diagnostic groups. SETTING AND SAMPLE POPULATION Sixty-eight subjects (44 women, 24 men) gave informed consent. Diagnostic criteria for temporomandibular disorders (DC/TMD) and imaging were used to group subjects according to presence of jaw muscle or joint pain (+P) and bilateral disk displacement (+DD). MATERIAL AND METHODS Subjects (+P+DD, n=16; -P+DD, n=16; and -P-DD, n=36) provided cone-beam computed tomography and magnetic resonance images, and jaw-tracking data. Numerical modeling was used to determine TMJ loads (Fnormal). Dynamic stereometry was used to characterize individual-specific data of stress-field dynamics during 10 symmetrical jaw-closing cycles. These data were used to estimate tractional forces (Ftraction). Energy densities were then calculated as W/Q (W=work done or mechanical energy input=tractional force×distance of stress-field translation, Q=volume of cartilage). anova and Tukey-Kramer post hoc analyses tested for intergroup differences. RESULTS Mean±standard error energy density for the +P+DD group was 12.7±1.5 mJ/mm³ and significantly greater (all adjusted p<0.04) when compared to -P+DD (7.4±1.4 mJ/mm³) and -P-DD (5.8±0.9 mJ/mm³) groups. Energy densities in -P+DD and -P-DD groups were not significantly different. CONCLUSION Diagnostic group differences in energy densities suggest that mechanical work may be a unique mechanism, which contributes to cartilage fatigue in subjects with pain and disk displacement.
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Affiliation(s)
- L M Gallo
- Center of Dental Medicine, Clinic of Masticatory Disorders, Removable Prosthodontics, Geriatric and Special Care Dentistry, University of Zurich, Zurich, Switzerland
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Nickel JC, Gonzalez YM, McCall WD, Ohrbach R, Marx DB, Liu H, Iwasaki LR. Muscle organization in individuals with and without pain and joint dysfunction. J Dent Res 2012; 91:568-73. [PMID: 22522774 DOI: 10.1177/0022034512445909] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Central nervous system organization of masticatory muscles determines the magnitude of joint and muscle forces. Validated computer-assisted models of neuromuscular organization during biting were used to determine organization in individuals with and without temporomandibular disorders (TMD). Ninety-one individuals (47 women, 44 men) were assigned to one of four diagnostic groups based on the presence (+) or absence (-) of pain (P) and bilateral temporomandibular joint disc displacement (DD). Electromyography and bite-forces were measured during right and left incisor and molar biting. Two three-dimensional models employing neuromuscular objectives of minimization of joint loads (MJL) or muscle effort (MME) simulated biting tasks. Evaluations of diagnostic group and gender effects on choice of best-fit model were by analysis of variance (ANOVA) and Tukey-Kramer post hoc tests, evaluations of right-left symmetry were by Chi-square and Fisher's exact statistics, and evaluations of model accuracy were by within-subject linear regressions. MME was the best-fit during left molar biting in +DD individuals and incisor biting in men (all p < 0.03). Incisor biting symmetry in muscle organization was significantly higher (p < 0.03) in healthy individuals compared with those with TMD. Within-subject regressions showed that best-fit model errors were similar among groups: 8 to 15% (0.68 ≤ R(2) ≤ 0.74). These computer-assisted models predicted muscle organization during static biting in humans with and without TMDs.
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Affiliation(s)
- J C Nickel
- University of Missouri-Kansas City, School of Dentistry, Department of Orthodontics & Dentofacial Orthopedics, Kansas City, MO 64108, USA
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Gonzalez Y, Iwasaki LR, McCall WD, Ohrbach R, Lozier E, Nickel JC. Reliability of electromyographic activity vs. bite-force from human masticatory muscles. Eur J Oral Sci 2011; 119:219-24. [PMID: 21564316 DOI: 10.1111/j.1600-0722.2011.00823.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The reproducibility of electromyographic (EMG) activity in relation to static bite-force from masticatory muscles for a given biting situation is largely unknown. Our aim was to evaluate the reliability of EMG activity in relation to static bite-force in humans. Eighty-four subjects produced five unilateral static bites of different forces at different biting positions on molars and incisors, at two separate sessions, and the surface EMG activities were recorded from temporalis, masseter, and suprahyoid muscles bilaterally. Intraclass correlation coefficients (ICCs) were determined, and an ICC of ≥ 0.60 indicated good reliability of these slopes. The ICCs for jaw-closing muscles during molar biting were: temporalis muscles, ipsilateral 0.58-0.93 and contralateral 0.88-0.91; and masseter muscles, ipsilateral 0.75-0.86 and contralateral 0.69-0.88. The ICCs for jaw-closing muscles during incisor biting were: temporalis muscles, ipsilateral 0.56-0.81 and contralateral 0.34-0.86; and masseter muscles, ipsilateral 0.65-0.78 and contralateral 0.59-0.80. For the suprahyoid muscles the 95% CIs were mostly wide and most included zero. The slopes of the EMG activity vs. bite-force for a given biting situation were reliable for temporalis and masseter muscles. These results support the use of these outcome measurements for the estimation and validation of mechanical models of the masticatory system.
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Affiliation(s)
- Y Gonzalez
- Department of Oral Diagnostic Sciences, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA.
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Iwasaki LR, Crosby MJ, Marx DB, Gonzalez Y, McCall WD, Ohrbach R, Nickel JC. Human temporomandibular joint eminence shape and load minimization. J Dent Res 2010; 89:722-7. [PMID: 20554892 DOI: 10.1177/0022034510364492] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Analysis of previous data suggested the hypothesis that temporomandibular joint (TMJ) eminence shapes develop ideally to minimize joint loads. Hence, we tested this hypothesis in nine females and eight males in each of two groups, with and without TMJ disc displacement. Participants provided anatomical data used in a joint load minimization numerical model to predict, and jaw-tracking data used to measure, eminence shapes. Coordinate data (x,y) of shapes were fit to third-order polynomials for two sessions, sides, and methods (predicted, measured) for each participant. Inter-session data were reliable and averaged. Those with, compared with those without, disc displacement had higher measured shape range (5:1) and left-right asymmetry prevalence (4:1). In 29 symmetrical individuals, ANCOVA and Bonferroni tests compared vertical dimensions (y) at 11 postero-anterior points (x), 0.5 mm apart. Model-predicted and measured shapes were significantly different (P < or = 0.01) near the eminence crest, but joint load minimization was consistent with eminence shape for x < 3.0 mm.
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Affiliation(s)
- L R Iwasaki
- University of Missouri-Kansas City, School of Dentistry, Department of Orthodontics & Dentofacial Orthopedics, 650 E. 25th St., Kansas City, MO 64108-2784, USA.
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Iwasaki LR, Chandler JR, Marx DB, Pandey JP, Nickel JC. IL-1 gene polymorphisms, secretion in gingival crevicular fluid, and speed of human orthodontic tooth movement. Orthod Craniofac Res 2009; 12:129-40. [DOI: 10.1111/j.1601-6343.2009.01446.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Spilker RL, Nickel JC, Iwasaki LR. A biphasic finite element model of in vitro plowing tests of the temporomandibular joint disc. Ann Biomed Eng 2009; 37:1152-64. [PMID: 19350392 DOI: 10.1007/s10439-009-9685-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 03/25/2009] [Indexed: 10/20/2022]
Abstract
Disorders of the temporomandibular joint (TMJ) afflict 3-29% of people aged 19-40 years. Degenerative joint disease (DJD) of the TMJ generally occurs 15 years earlier than in other human joints and 1.5-2 times more often in women than men. The TMJ disc is the primary stress distribution mechanism within the joint. Mechanical failure of the TMJ disc precedes clinical signs of DJD. Unlike postcranial synovial joints, biomimetic replacements of the disc have not been successful, probably due to the paucity of knowledge about TMJ biomechanics. Translation of stress-fields mediolaterally across the TMJ disc may lead to fatigue failure because of the effect of traction forces on the tissue surface and because the disc is relatively weak in this aspect. Traction forces are composed of friction forces, which are known to be low in the TMJ, and plowing forces which are relatively much higher and result from movement and pressurization of fluids within the tissues due to translating surface loads. In the in vitro plowing experiment, a rigid curve-ended indenter is lowered into a TMJ disc that has been mounted on a stage with pressure gauges, and the indenter is then translated in a prescribed mediolateral motion that is intended to simulate the motion of the mandibular condyle on the TMJ disc in vivo. As a first step, these plowing experiments have quantified the variables thought to be important in tissue failure. A next step is to define the full role of these variables in the pathomechanics of TMJ disc tissue through a validated model. Therefore, the aim of this study was to develop and test a finite element model of the plowing experiments based on an orthotropic biphasic description of the soft tissue behavior of the TMJ disc. For this plowing model, the arbitrary Lagrange Eulerian method was used to approximate the moving load problem, where in vitro the indenter slid along the tissue's superior surface. Approximate validation of the plowing model was based on comparisons of model-predicted temporal and spatial distribution of indenter displacement and total normal stresses (+/-15%) and laboratory measurements during one complete cycle of plowing motion. Other useful predictions from the plowing model include spatial and temporal distributions of biomechanical variables of interest that cannot be measured experimentally, such as total stress, pressure, strain, and the relative significance of the orthotropic solid phase properties.
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Affiliation(s)
- R L Spilker
- Department of Biomedical Engineering, Jonsson Engineering Center, Rensselaer Polytechnic Institute, 110 8th St., Troy, NY 12180-3590, USA.
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Abstract
The pathomechanics of degenerative joint disease of the temporomandibular joint (TMJ) may involve fatigue produced by mechanical work on the articulating tissues. This study tested the hypotheses that mechanical work in the TMJ (i) varies with the type of mandibular activity, and (ii) is evenly distributed over TMJ surfaces. Ten healthy human participants were recorded with Magnetic Resonance Imaging (MRI) and jaw tracking. The data were used to reconstruct and animate TMJ activity. Aspect ratios, instantaneous velocities, and distances of stress-fields translation were used to calculate work (mJ). The results were analyzed by least-squares polynomial regression and ANOVA. Work magnitudes were related to peak velocity (R(2) = 0.92) and distance of stress-field translation (R(2) = 0.83), and were distributed over the joint surfaces (p < 0.03). During mandibular laterotrusion, average mechanical work was 1.5 times greater in the contralateral joint. Peak magnitudes of work (> 3000 mJ) were 4 times that previously reported.
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Affiliation(s)
- L M Gallo
- Clinic for Masticatory Disorders and Complete Dentures, Center for Oral Medicine, Dental and Maxillo-Facial Surgery, University of Zürich, Plattenstrasse 11, CH-8028 Zürich, Switzerland.
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Abstract
UNLABELLED Mechanical fatigue-related degeneration of the temporomandibular joint (TMJ) disc may be promoted by tractional forces. This study tested the hypotheses that tractional forces following static loading of the TMJ disc: (1) increase with compressive strain at the start of movement, and (2) are velocity-dependent during movement. Sixty-four porcine discs received a 10-N static load via an acrylic indenter for 1 or 30 sec before cyclic movement. Physical data were recorded and analyzed by ANOVA. The results showed that compressive strain and tractional forces were largest for the start of movement following 30 sec of static loading (p <or= 0.0001) and were correlated (R(2) = 0.84). Peak tractional forces were linearly and positively related to velocity of movement (R(2) = 0.85), and were highest during Cycle 1 after 30 sec of loading (p <or= 0.0067). The results demonstrated that tractional forces were strain-related at the start of movement and velocity-dependent during movement. ABBREVIATIONS ANOVA = analysis of variance, PBS = phosphate-buffered physiological saline solution, TMJ = temporomandibular joint, mu(T) =tractional coefficient, mu(s) = static coefficient of friction.
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Affiliation(s)
- J C Nickel
- University of Nebraska Medical Center College of Dentistry, Department of Growth and Development, PO Box 683740, Lincoln, NE 68583-0755, USA.
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Abstract
OBJECTIVE The central nervous system controls the muscles of mastication and may dictate muscle outputs according to a biologically important objective. This study tested the hypotheses that (a) the effective sagittal TMJ eminence morphology, and (b) the outputs of the masticatory muscles during static biting, are consistent with minimisation of joint loads or minimisation of muscle effort. DESIGN Numerical modelling predicted effective eminence morphology (from sagittal plane directions of TMJ force for centred loading over a range from molar to incisor biting) and TMJ and muscle forces during static unilateral biting in seven subjects. In vivo effective eminence morphology was measured from jaw tracking recorded from each subject. Muscle activities during biting tasks on first molar and incisor teeth were measured by electromyography using surface or indwelling electrodes. RESULTS Subject-specific predicted effective eminence morphology correlated with in vivo data (0.85< or =R2< or =0.99). Mixed and random coefficient analysis of covariance indicated good agreement between predicted and measured muscle outputs for all muscles of mastication investigated. Individual linear regression analysis showed that modelled muscle outputs accurately predicted EMG data, with average errors of 8% for molar and 15% for incisor biting. CONCLUSIONS Effective sagittal eminence morphology was consistent with minimisation of joint loads for all subjects. Masticatory muscle outputs during unilateral biting were consistent with minimisation of joint loads or minimisation of muscle effort, or both, depending on the subject. These results are believed to be the first to test model predictions of muscle output during biting for all muscles of mastication.
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Affiliation(s)
- L R Iwasaki
- Department of Growth and Development, College of Dentistry, University of Nebraska Medical Center, 40th & Holdrege Streets, Room 158G, P.O. Box 830740, Lincoln, NE 68583-0755, USA
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Abstract
Muscle forces determine joint loads, but the objectives governing the mix of muscle forces involved are unknown. This study tested the hypothesis that masticatory muscle forces exerted during static biting are consistent with objectives of minimization of joint loads (MJL) or muscle effort (MME). To do this, we compared numerical model predictions with data measured from six subjects. Biting tasks which produced moments on molar and incisor teeth were modeled based on MJL or MME. The slope of predicted vs. electromyographic (EMG) data for an individual was compared with a perfect match slope of 1.00. Predictions based on MME matched best with EMG activity for molar biting (slopes, 0.89-1.16). Predictions from either or both models matched EMG results for incisor biting (best-match slopes, 0.95-1.07). Muscle forces during isometric biting appear to be consistent with objectives of MJL or MME, depending on the individual, biting location, and moment.
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Affiliation(s)
- J C Nickel
- University of Nebraska Medical Center College of Dentistry, Department of Growth and Development, 40th and Holdrege Streets, PO Box 830740, Lincoln, NE 68583-0755, USA
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Beatty MW, Bruno MJ, Iwasaki LR, Nickel JC. Strain rate dependent orthotropic properties of pristine and impulsively loaded porcine temporomandibular joint disk. J Biomed Mater Res 2001; 57:25-34. [PMID: 11416845 DOI: 10.1002/1097-4636(200110)57:1<25::aid-jbm1137>3.0.co;2-h] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this study was to characterize the tensile stress-strain behavior of the porcine temporomandibular joint (TMJ) disk with respect to collagen orientation and strain rate dependency. The apparent elastic modulus, ultimate tensile strength, and strain at maximum stress were measured at three elongation rates (0.5, 50, and 500 mm/min) for dumbbell-shaped samples oriented along either anteroposterior or mediolateral axes of the disks. In order to study the effects of impact-induced fissuring on the mechanical behavior, the same properties were measured along each orientation at an elongation rate of 500 mm/min for disks subjected to impulsive loads of 0.5 N. s. The results suggested a strongly orthotropic nature to the healthy pristine disk. The values for the apparent modulus and ultimate strength were 10-fold higher along the anteroposterior axis (p < or = 0.01), which represented the primary orientation of the collagen fibers. Strain rate dependency was evident for loading along the anteroposterior axis but not along the mediolateral axis. No significant differences in any property were noted between pristine and impulsively loaded disks for either orientation (p > 0.05). The results demonstrated the importance of choosing an orthotropic model for the TMJ disk to conduct finite element modeling, to develop failure criteria, and to construct tissue-engineered replacements. Impact-induced fissuring requires further study to determine if the TMJ disk is orthotropic with respect to fatigue.
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Affiliation(s)
- M W Beatty
- Section of Biomaterials, Department of Adult Restorative Dentistry, UNMC College of Dentistry, 40th and Holdrege Streets, Lincoln, Nebraska 68583-0750, USA.
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Iwasaki LR, Haack JE, Nickel JC, Reinhardt RA, Petro TM. Human interleukin-1 beta and interleukin-1 receptor antagonist secretion and velocity of tooth movement. Arch Oral Biol 2001; 46:185-9. [PMID: 11163326 DOI: 10.1016/s0003-9969(00)00088-1] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The cytokines interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1RA) probably play a part in orthodontic tooth movement. Here, the force magnitudes and the area of force application in the compressed periodontal ligament (PDL) were controlled and the velocity of tooth movement correlated with concentrations of IL-1 beta and IL-1RA in the gingival crevicular fluid (GCF). Seven individuals undergoing orthodontic treatment involving maxillary first premolar extractions and distal movement (bodily retraction) of the maxillary canines participated in the 84-day study. For each participant, continuous retraction forces were applied so that they received equivalent PDL stresses of 13 kPa for one canine and 4 kPa for the other. GCF cytokine concentrations from experimental and control teeth were expressed relative to total protein in the GCF and compared using an 'Activity Index' (AI)=Experimental (IL-1 beta/IL-1RA)/Control (IL-1 beta/IL-1RA). The results showed that the velocity of tooth movement in an individual was related to their AI. The correlation between AI and tooth movement was stronger from the distal (R(d)=0.78) than from the mesial (R(m)=0.65) of retracted teeth. The results demonstrate that equivalent force systems produce individual differences in cytokine production, which correlate with interindividual differences in the velocity of canine retraction.
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Affiliation(s)
- L R Iwasaki
- Department of Growth and Development, College of Dentistry, University of Nebraska Medical Center, P.O. Box 830740, Lincoln, NE 68583-0755, USA.
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Nickel JC, Iwasaki LR, Feely DE, Stormberg KD, Beatty MW. The effect of disc thickness and trauma on disc surface friction in the porcine temporomandibular joint. Arch Oral Biol 2001; 46:155-62. [PMID: 11163323 DOI: 10.1016/s0003-9969(00)00101-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The pathomechanics of osteoarthritis in the human temporomandibular joint (TMJ) are unknown. Compromised lubrication is a potential factor, but, lubrication within even the normal TMJ is not understood completely. Weeping lubrication is a concept that may be applicable to the TMJ. A characteristic of weeping lubrication is a slow increase in friction during static loading. The rate of increase in friction is related to the rate of lateral movement of synovial fluid away from the loading area. The TMJ disc is expected to be the main source of TMJ lubrication. This study tested two variables, disc thickness and magnitude of trauma to the disc, as factors that can affect the rate of flow of synovial fluid and thus alter lubrication of the disc surfaces. To test these variables, TMJ disc surface friction was measured before and after an impulse load. Before the impulse load, all discs demonstrated a gradual increase in friction during light static loading. The rate of increase in friction was inversely related to the disc thickness (R(2)=0.75). After an impulse load of known magnitude and peak force, disc surface friction was higher. The magnitude of this surface friction was correlated with the magnitude of the impulsive blow (R(2)=0.89) and the area of surface damage (R(2)=0.85). Disc thickness was a significant factor in determining the minimal impulse needed to produce higher surface friction (R(2)=0.99). These results confirm that disc thickness and trauma to the disc affect surface friction in the TMJ, and therefore may be important factors in compromised lubrication and the development of osteoarthritis.
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Affiliation(s)
- J C Nickel
- Department of Growth and Development, University of Nebraska Medical Center, College of Dentistry, P.O. Box 830740, Lincoln, NE 68583-0755, USA.
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Abstract
Movement over the surface of the temporomandibular joint (TMJ) disc produces tractional forces. These forces potentially increase the magnitude of shear stresses and contribute to wear and fatigue of the disc. Theoretically, tractional forces in all synovial joints are the result of frictional forces, due to rubbing of the cartilage surfaces, and plowing forces, due to translation of the stress-field through the cartilage matrix as the joint surface congruency changes during motion. For plowing forces to occur in the TMJ, there must be mediolateral translation of the stress-field as the condyle moves dorsoventrally during jaw function. To test whether mediolateral stress-field translation occurs in the intact TMJ, we measured stress-field position and translation velocities in ten normal individuals during rhythmic jaw opening and closing. Magnetic resonance imaging and jaw tracking were combined to animate the three-dimensional position of the stress-field between the articulating surfaces. This allowed for mediolateral translation velocity measurements of the centroid of the stress-field. The results showed that during jaw opening and closing at 0.5 Hz, the average peak mediolateral translation velocity was 35 +/- 17 mm/sec. When opening and closing increased to 1.0 Hz, the average peak velocity was 40 +/- 19 mm/sec. Theoretical model estimates of the work done during such translation ranged from 6 to 709 mJ between the individual joints studied. The potential clinical importance of this measure is that long-term exposure of the TMJ disc to high work may result in fatigue failure of the TMJ disc.
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Affiliation(s)
- L M Gallo
- Clinic for Masticatory Disorders, Center for Oral Medicine, Dental and Maxillo-Facial Surgery, University of Zürich, Switzerland.
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Abstract
Conventional orthodontic therapy often uses force magnitudes in excess of 100 g to retract canine teeth. Typically, this results in a lag phase of approximately 21 days before tooth movement occurs. The current project was undertaken to demonstrate that by using lower force magnitudes, tooth translation can start without a lag phase and can occur at velocities that are clinically significant. Seven subjects participated in the 84-day study. A continuous retraction force averaging 18 g was applied to 1 of the maxillary canines, whereas a continuous retraction force averaging 60 g was applied to the other. The magnitude was adjusted for each canine to produce equivalent compressive stresses between subjects. Estimated average compressive stress on the distal aspect of the canine teeth was 4 kPa or 13 kPa. The moment-to-force ratios were between 9 and 13 mm. Tooth movement in 3 linear and 3 rotational dimensions was measured with a 3-axis measuring microscope and a series of dental casts made at 1- to 14-day intervals. The results showed a statistical difference in the velocity of distal movement of the canines produced by the 2 stresses (P =.02). The lag phase was eliminated and average velocities were 0.87 and 1.27 mm/month for 18 and 60 g of average retraction force. Interindividual velocities varied as much as 3 to 1 for equivalent stress conditions. It was concluded that effective tooth movement can be produced with lower forces and that because loading conditions were controlled, cell biology must account for the variability in tooth velocities measured in these subjects.
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Affiliation(s)
- L R Iwasaki
- Department of Growth and Development, University of Nebraska Medical Center, College of Dentistry, Lincoln 68583-0755, USA.
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