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Kim DG, Kwon HJ, Jeong YH, Chien HH, Crance S, Agnew AM, Battula S, Lee JW, Wen HB. Associations of Resonance Frequency Analysis with Dynamic Mechanical Analysis of Dental Implant Systems. Clin Implant Dent Relat Res 2015; 18:332-41. [PMID: 25810026 DOI: 10.1111/cid.12319] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Resonance frequency analysis (RFA) has been introduced as a noninvasive method to clinically estimate the stability of dental implant systems. PURPOSE The objective of this study was to examine whether implant stability quotient (ISQ) values of RFA can account for mechanical stability of the dental implant system, which is assessed using dynamic mechanical analysis (DMA). MATERIALS AND METHODS Fifty-seven screw-type titanium dental implants were placed in artificial polyurethane foams with seven different thicknesses (3.5 to 12 mm) and eight edentulous mandibles of human cadavers (four men and four women, 79.11 ± 13.48 years). After the ISQ values, insertion torque, and static stiffness of each implant system were measured, the DMA was performed to assess dynamic stiffness and viscoelastic tan δ. RESULTS The ISQ value had strong positive correlations with thickness, insertion torque, static and dynamic stiffness, and a negative correlation with tan δ of implant systems in artificial bone blocks (r = 0.769 to 0.992, p < .043). However, the ISQ value was correlated with only the insertion torque of implant systems in human mandibles (p < .049). CONCLUSION The ISQ values could reflect mechanical stability of the dental implant system under the controlled condition of homogeneous density in simple dimensions.
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Affiliation(s)
- Do-Gyoon Kim
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Hyun-Jung Kwon
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Yong-Hoon Jeong
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Hua-Hong Chien
- Division of Periodontology, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Samantha Crance
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Amanda M Agnew
- Division of Anatomy, College of Medicine, The Ohio State University, Columbus, OH, USA
| | | | - Jin Whan Lee
- Dental Research, Zimmer Dental Inc., Carlsbad, CA, USA
| | - Hai Bo Wen
- Dental Research and Clinical Affairs, Zimmer Dental Inc., Carlsbad, CA, USA
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102
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Jeltema M, Beckley J, Vahalik J. Model for understanding consumer textural food choice. Food Sci Nutr 2015; 3:202-12. [PMID: 25987995 PMCID: PMC4431788 DOI: 10.1002/fsn3.205] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 09/29/2014] [Accepted: 10/16/2014] [Indexed: 11/09/2022] Open
Abstract
The current paradigm for developing products that will match the marketing messaging is flawed because the drivers of product choice and satisfaction based on texture are misunderstood. Qualitative research across 10 years has led to the thesis explored in this research that individuals have a preferred way to manipulate food in their mouths (i.e., mouth behavior) and that this behavior is a major driver of food choice, satisfaction, and the desire to repurchase. Texture, which is currently thought to be a major driver of product choice, is a secondary factor, and is important only in that it supports the primary driver-mouth behavior. A model for mouth behavior is proposed and the qualitative research supporting the identification of different mouth behaviors is presented. The development of a trademarked typing tool for characterizing mouth behavior is described along with quantitative substantiation of the tool's ability to group individuals by mouth behavior. The use of these four groups to understand textural preferences and the implications for a variety of areas including product design and weight management are explored.
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Affiliation(s)
- Melissa Jeltema
- The Understanding & Insight Group LLC 15501 Genito Road, Midlothian, Virginia, 23112
| | - Jacqueline Beckley
- The Understanding & Insight Group LLC 3 Rosewood Lane, Suite 103, Denville, New Jersey, 07834
| | - Jennifer Vahalik
- The Understanding & Insight Group LLC 3 Rosewood Lane, Suite 103, Denville, New Jersey, 07834
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103
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Majd B, Majd H, Porter JA, Romberg E, Arola D. Degradation in the fatigue strength of dentin by diamond bur preparations: Importance of cutting direction. J Biomed Mater Res B Appl Biomater 2015; 104:39-49. [PMID: 25611951 DOI: 10.1002/jbm.b.33348] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 11/16/2014] [Accepted: 12/02/2014] [Indexed: 11/12/2022]
Abstract
The objectives of this investigation were to evaluate the degradation in fatigue strength of dentin by diamond bur preparations and to identify the importance of cutting direction. Three groups of coronal dentin specimens were prepared from unrestored third molars, including a flaw free "control," and two groups that received a diamond bur cutting treatment performed parallel or perpendicular to the specimen length. The specimens were subjected to static or cyclic flexural loading to failure and the results were compared with data for carbide bur cutting. Under static loading diamond bur cutting resulted in significantly lower flexure strength (p ≤ 0.05) than the control for both cutting directions (from 154 to ∼124 MPa). However, there was no significant difference in the strength between the control and carbide bur treated specimens. Similarly, the fatigue strength of the diamond bur treated specimens was significantly lower (p ≤ 0.0001) than that of the control for both cutting directions. Cutting in the perpendicular direction resulted in nearly 60% reduction to the endurance limit (from 44 to 19 MPa). Based on the results, diamond bur cutting of cavity preparations causes a reduction in the fatigue strength of dentin, regardless of the cutting direction. To maintain the durability of dentin, cavity preparations introduced using diamond burs must be performed with appropriate cutting direction and followed by a finishing pass.
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Affiliation(s)
- B Majd
- Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, Maryland
| | - H Majd
- Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, Maryland
| | - J A Porter
- Department of Endodontics, Prosthodontics and Operative Dentistry, Dental School, University of Maryland, Baltimore, Maryland
| | - E Romberg
- Department of Endodontics, Prosthodontics and Operative Dentistry, Dental School, University of Maryland, Baltimore, Maryland
| | - D Arola
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington.,Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Washington
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104
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Importance of age on the dynamic mechanical behavior of intertubular and peritubular dentin. J Mech Behav Biomed Mater 2014; 42:229-42. [PMID: 25498296 DOI: 10.1016/j.jmbbm.2014.11.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/20/2014] [Accepted: 11/22/2014] [Indexed: 11/23/2022]
Abstract
An experimental evaluation of human coronal dentin was performed using nanoscopic dynamic mechanical analysis (nanoDMA). The primary objectives were to quantify any unique changes in mechanical behavior of intertubular and peritubular dentin with age, and to evaluate the microstructure and mechanical behavior of the mineral deposited within the lumens. Specimens of coronal dentin were evaluated by nanoDMA using single indents and in scanning mode via scanning probe microscopy. Results showed that there were no significant differences in the storage modulus or complex modulus between the two age groups (18-25 versus 54-83 yrs) for either the intertubular or peritubular tissue. However, there were significant differences in the dampening behavior between the young and old dentin, as represented in the loss modulus and tanδ responses. For both the intertubular and peritubular components, the capacity for dampening was significantly lower in the old group. Scanning based nanoDMA showed that the tubules of old dentin exhibit a gradient in elastic behavior, with decrease in elastic modulus from the cuff to the center of tubules filled with newly deposited mineral.
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105
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Cheong JN, Foster KD, Morgenstern MP, Grigor JM, Bronlund JE, Hutchings SC, Hedderley DI. The Application of Temporal Dominance of Sensations (TDS) for Oral Processing Studies: An Initial Investigation. J Texture Stud 2014. [DOI: 10.1111/jtxs.12091] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Jean Ne Cheong
- Institute of Food, Nutrition & Human Health; Massey University; Private Bag 102904, North Shore Mail Centre Auckland 0745 New Zealand
| | - Kylie D. Foster
- Institute of Food, Nutrition & Human Health; Massey University; Private Bag 102904, North Shore Mail Centre Auckland 0745 New Zealand
| | - Marco P. Morgenstern
- The New Zealand Institute for Plant & Food Research Limited; Christchurch New Zealand
| | - John M.V. Grigor
- Institute of Food, Nutrition & Human Health; Massey University; Private Bag 102904, North Shore Mail Centre Auckland 0745 New Zealand
- The Riddet Institute; Massey University; Palmerston North New Zealand
| | - John E. Bronlund
- The Riddet Institute; Massey University; Palmerston North New Zealand
- School of Engineering and Advanced Technology; Massey University; Palmerston North New Zealand
| | - Scott C. Hutchings
- Institute of Food, Nutrition & Human Health; Massey University; Private Bag 102904, North Shore Mail Centre Auckland 0745 New Zealand
| | - Duncan I. Hedderley
- The New Zealand Institute for Plant & Food Research Limited; Palmerston North New Zealand
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106
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Degradation in the fatigue strength of dentin by cutting, etching and adhesive bonding. Dent Mater 2014; 30:1061-72. [PMID: 24985539 DOI: 10.1016/j.dental.2014.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 06/07/2014] [Accepted: 06/09/2014] [Indexed: 11/20/2022]
Abstract
UNLABELLED The processes involved in placing resin composite restorations may degrade the fatigue strength of dentin and increase the likelihood of fractures in restored teeth. OBJECTIVE The objective of this study was to evaluate the relative changes in strength and fatigue behavior of dentin caused by bur preparation, etching and resin bonding procedures using a 3-step system. METHODS Specimens of dentin were prepared from the crowns of unrestored 3rd molars and subjected to either quasi-static or cyclic flexural loading to failure. Four treated groups were prepared including dentin beams subjected to a bur treatment only with a conventional straight-sided bur, or etching treatment only. An additional treated group received both bur and etching treatments, and the last was treated by bur treatment and etching, followed by application of a commercial resin adhesive. The control group consisted of "as sectioned" dentin specimens. RESULTS Under quasi-static loading to failure there was no significant difference between the strength of the control group and treated groups. Dentin beams receiving only etching or bur cutting treatments exhibited fatigue strengths that were significantly lower (p≤0.0001) than the control; there was no significant difference in the fatigue resistance of these two groups. Similarly, the dentin receiving bur and etching treatments exhibited significantly lower (p≤0.0001) fatigue strength than that of the control, regardless of whether an adhesive was applied. SIGNIFICANCE The individual steps involved in the placement of bonded resin composite restorations significantly decrease the fatigue strength of dentin, and application of a bonding agent does not increase the fatigue strength of dentin.
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107
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Lin CL, Kuo WC, Chang YH, Yu JJ, Lin YC. Examination of ceramic/enamel interfacial debonding using acoustic emission and optical coherence tomography. Dent Mater 2014; 30:910-6. [PMID: 24958691 DOI: 10.1016/j.dental.2014.05.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 04/04/2014] [Accepted: 05/21/2014] [Indexed: 10/25/2022]
Abstract
OBJECTIVE This study investigates monitored micro-crack growth and damage in the ceramic/enamel adhesive interface using the acoustic emission (AE) technique with optical coherence tomography (OCT) under fatigue shear testing. METHODS Shear bond strength (SBS) was measured first with eight prepared ceramic/enamel adhesive specimens under static loads. The fatigue shear testing was performed with three specimens at each cyclic load according to a modified ISO14801 method, applying at 80%, 75%, 70%, and 65% of the SBS to monitor interface debonding. The number of cycles at each load was recorded until ceramic/enamel adhesive interface debonding occurred. The AE technique was used to detect micro-crack signals in static and fatigue shear bond tests. RESULTS The results showed that the average SBS value in the static tests was 18.07 ± 1.72 MPa (mean ± standard deviation), expressed in Newton's at 56.77 ± 5.40N. The average number of fatigue cycles in which ceramic/enamel interface damage was detected in 80%, 75%, 70% and 65% of the SBS were 41, 410, 8141 and 76,541, respectively. The acoustic behavior varied according to the applied load level. Events were emitted during 65% and 70% fatigue tests. A good correlation was observed between the crack location in OCT images and the number of AE signal hits. SIGNIFICANCE The AE technique combined with OCT images as a pre-clinical assessment tool to determine the integrity of cemented load bearing restored ceramic material. Sustainable cyclic load stresses in ceramic/enamel bonded specimens were substantially lower than the measured SBS. Predicted S-N curve showed that the maximum endured load was 10.98 MPa (about 34.48 N) passing 10(6) fatigue cyclic.
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Affiliation(s)
- Chun-Li Lin
- Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan.
| | - Wen-Chuan Kuo
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan.
| | - Yen-Hsiang Chang
- Department of General Dentistry, Chang Gung Memorial Hospital, Tao-yuan, Taiwan.
| | - Jin-Jie Yu
- Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan.
| | - Yun-Chu Lin
- Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan.
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108
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Shibata S, Gondo R, Araújo É, Mello Roesler CRD, Baratieri LN. Influence of surrounding wall thickness on the fatigue resistance of molars restored with ceramic inlay. Braz Oral Res 2014; 28:S1806-83242014000100229. [PMID: 24918366 DOI: 10.1590/1807-3107bor-2014.vol28.0011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 02/19/2014] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on the fatigue resistance of molars restored with CAD/CAM ceramic inlays. Forty human third molars were selected and divided into 4 groups, according to the remaining surrounding wall thickness chosen for inlay preparation (n=10): G1, 2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were made from feldspathic ceramic blocks by a CAD/CAM system, and cemented adhesively. After 1 week stored in distilled water at 37 °C, the specimens were subjected to fatigue testing under the following protocol: 5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of 400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimens were cycled until failure or completion of 185,000 cycles. The survival rate of the groups was compared using the Kaplan-Meier survival curves (p>0.05). All specimens withstood the fatigue protocol (185,000 cycles), representing a 100% survival rate. The Kaplan-Meier survival curves showed no difference between groups. It can be concluded that the remaining tooth wall thickness did not influence the fatigue resistance of molars restored with CAD/CAM ceramic inlays.
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Affiliation(s)
- Shizuma Shibata
- Department of Dental Sciences, Centre of Heath Sciences, Univ. Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Renata Gondo
- Department of Dental Sciences, Centre of Heath Sciences, Univ. Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Élito Araújo
- Department of Dental Sciences, Centre of Heath Sciences, Univ. Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Carlos Rodrigo de Mello Roesler
- Deparment of Mechanical Engineering, Biomechanics Engineering Laboratory, University Hospital, Univ. Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Luiz Narciso Baratieri
- Department of Dental Sciences, Centre of Heath Sciences, Univ. Federal de Santa Catarina, Florianópolis, SC, Brazil
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109
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Sakoguchi K, Minami H, Suzuki S, Tanaka T. Evaluation of fracture resistance of indirect composite resin crowns by cyclic impact test: influence of crown and abutment materials. Dent Mater J 2014; 32:433-40. [PMID: 23719005 DOI: 10.4012/dmj.2012-313] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study evaluated the effect of abutment materials on the fracture resistance of composite crowns for premolars. Composite crowns were fabricated using two different indirect composite resin materials (Meta Color Prime Art or Estenia C&B) and cemented onto either a metal (Castwell M.C. 12) or composite resin (Build-It FR and FibreKor) abutment with resin cement (Panavia F2.0). Twenty-four specimens were fabricated for four groups (n=6 each) and subjected to 280-N cyclic impact loading at 1.0 Hz. The number of cycles which caused the composite crown to fracture was defined as its fracture resistance. All data were statistically analyzed using ANOVA and the Bonferroni test (α=0.05). Composite crowns cemented onto resin abutments showed higher fracture resistance than those cemented onto metal abutments.
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Affiliation(s)
- Kenji Sakoguchi
- Department of Fixed Prosthetic Dentistry, Advanced Therapeutic Course, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan
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110
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Singh V, Misra A, Parthasarathy R, Ye Q, Spencer P. Viscoelastic properties of collagen-adhesive composites under water-saturated and dry conditions. J Biomed Mater Res A 2014; 103:646-57. [PMID: 24753362 DOI: 10.1002/jbm.a.35204] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 03/05/2014] [Accepted: 04/18/2014] [Indexed: 11/06/2022]
Abstract
To investigate the time- and rate-dependent mechanical properties of collagen-adhesive composites, creep and monotonic experiments are performed under dry and wet conditions. The composites are prepared by infiltration of dentin adhesive into a demineralized bovine dentin. Experimental results show that for small stress level under dry conditions, both the composite and the neat adhesive have similar behavior. On the other hand, in wet conditions, the composites are significantly soft and weak compared to the neat adhesives. The behavior in the wet condition is found to be affected by the hydrophilicity of both the adhesive and the collagen. As the adhesive-collagen composites are a part of the complex construct that forms the adhesive-dentin interface, their presence will affect the overall performance of the restoration. We find that Kelvin-Voigt model with at least four elements is required to fit the creep compliance data, indicating that the adhesive-collagen composites are complex polymers with several characteristic time scales whose mechanical behavior will be significantly affected by loading rates and frequencies. Such mechanical properties have not been investigated widely for these types of materials. The derived model provides an additional advantage that it can be exploited to extract other viscoelastic properties which are, generally, time consuming to obtain experimentally. The calibrated model is utilized to obtain stress relaxation function, frequency-dependent storage and loss modulus, and rate-dependent elastic modulus.
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Affiliation(s)
- Viraj Singh
- Department of Mechanical Engineering, University of Kansas, Lawrence, Kansas, 66045-7609; Bioengineering Research Center, University of Kansas, Lawrence, Kansas, 66045-7609
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111
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Motoi L, Morgenstern MP, Hedderley DI, Wilson AJ, Balita S. Bolus Moisture Content of Solid Foods during Mastication. J Texture Stud 2013. [DOI: 10.1111/jtxs.12036] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lidia Motoi
- The New Zealand Institute for Plant & Food Research Limited; Private Bag 4704, Christchurch Mail Centre Christchurch 8140 New Zealand
| | - Marco P. Morgenstern
- The New Zealand Institute for Plant & Food Research Limited; Private Bag 4704, Christchurch Mail Centre Christchurch 8140 New Zealand
| | - Duncan I. Hedderley
- The New Zealand Institute for Plant & Food Research Limited; Palmerston North New Zealand
| | - Arran J. Wilson
- The New Zealand Institute for Plant & Food Research Limited; Private Bag 4704, Christchurch Mail Centre Christchurch 8140 New Zealand
| | - Sinag Balita
- The New Zealand Institute for Plant & Food Research Limited; Private Bag 4704, Christchurch Mail Centre Christchurch 8140 New Zealand
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112
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Su KC, Chuang SF, Ng EYK, Chang CH. An investigation of dentinal fluid flow in dental pulp during food mastication: simulation of fluid-structure interaction. Biomech Model Mechanobiol 2013; 13:527-35. [PMID: 23913183 DOI: 10.1007/s10237-013-0514-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 07/10/2013] [Indexed: 11/28/2022]
Abstract
This study uses fluid-structure interaction (FSI) simulation to investigate the relationship between the dentinal fluid flow in the dental pulp of a tooth and the elastic modulus of masticated food particles and to investigate the effects of chewing rate on fluid flow in the dental pulp. Three-dimensional simulation models of a premolar tooth (enamel, dentine, pulp, periodontal ligament, cortical bone, and cancellous bone) and food particle were created. Food particles with elastic modulus of 2,000 and 10,000 MPa were used, respectively. The external displacement loading (5 μm) was gradually directed to the food particle surface for 1 and 0.1 s, respectively, to simulate the chewing of food particles. The displacement and stress on tooth structure and fluid flow in the dental pulp were selected as evaluation indices. The results show that masticating food with a high elastic modulus results in high stress and deformation in the tooth structure, causing faster dentinal fluid flow in the pulp in comparison with that obtained with soft food. In addition, fast chewing of hard food particles can induce faster fluid flow in the pulp, which may result in dental pain. FSI analysis is shown to be a useful tool for investigating dental biomechanics during food mastication. FSI simulation can be used to predict intrapulpal fluid flow in dental pulp; this information may provide the clinician with important concept in dental biomechanics during food mastication.
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Affiliation(s)
- Kuo-Chih Su
- Department of Biomedical Engineering College of Engineering, National Cheng Kung University, 1 University Road, Tainan City, 701, Taiwan
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113
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Po JMC, Gallo LM, Michelotti A, Farella M. Comparison between the rhythmic jaw contractions occurring during sleep and while chewing. J Sleep Res 2013; 22:593-9. [DOI: 10.1111/jsr.12057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 03/24/2013] [Indexed: 01/08/2023]
Affiliation(s)
- Jessica M. C. Po
- Discipline of Orthodontics; Department of Oral Sciences; University of Otago; Dunedin New Zealand
| | - Luigi M. Gallo
- Clinic for Masticatory Disorders; Removable Prosthodontics and Special Care Dentistry; University of Zürich; Zürich Switzerland
| | - Ambra Michelotti
- Discipline of Orthodontics; Department of Oral Sciences; University of Naples Federico II; Naples Italy
| | - Mauro Farella
- Discipline of Orthodontics; Department of Oral Sciences; University of Otago; Dunedin New Zealand
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114
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Lin CL, Kuo WC, Yu JJ, Huang SF. Examination of ceramic restorative material interfacial debonding using acoustic emission and optical coherence tomography. Dent Mater 2013; 29:382-8. [DOI: 10.1016/j.dental.2012.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 10/23/2012] [Accepted: 12/14/2012] [Indexed: 10/27/2022]
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115
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Neck and shoulder muscle activity of orthodontists in natural environments. J Electromyogr Kinesiol 2013; 23:600-7. [PMID: 23422325 DOI: 10.1016/j.jelekin.2013.01.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 11/20/2022] Open
Abstract
Work related musculoskeletal disorders (WMSDs) are common among dentists and possibly caused by prolonged static load. The aim of this study was to assess the contraction pattern of neck and shoulder muscles of orthodontists in natural environments. Electromyographic (EMG) activity of right sternocleidomastoid and trapezius muscles were recorded by means of portable recorders in eight orthodontists during working conditions, and both active and resting non-working conditions. Recordings were analysed in terms of contraction episode (CE) count, amplitude, and duration. The sternocleidomastoid and trapezius muscles contracted about 40-70times per hour in the natural environment. Their EMG activity pattern mainly consisted of short-lasting, low-amplitude CEs. The counts and amplitude of sternocleidomastoid CEs did not differ across vocational and non-vocational conditions. The number and amplitude of trapezius CEs were slightly but significantly higher during the vocational condition. There were highly significant (p<0.001) differences in duration of CEs across conditions, with two to threefold increase in the average duration of trapezius muscle contractions found in the vocational setting. During orthodontic work, operators commonly hold muscular contractions for significantly longer periods than are encountered in non-vocational settings. This behaviour may be associated causally with the increases seen in WMSDs through proposed pathophysiological mechanisms occurring at the motor unit level. Our findings may also be valid for other occupations characterised by seated static postures with precision hand and wrist movements.
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116
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Vinyard CJ, Glander KE, Teaford MF, Thompson CL, Deffenbaugh M, Williams SH. Methods for Studying the Ecological Physiology of Feeding in Free-Ranging Howlers (Alouatta palliata) at La Pacifica, Costa Rica. INT J PRIMATOL 2012. [DOI: 10.1007/s10764-012-9579-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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