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Abdelfattah RA, Nawar NN, Kataia EM, Saber SM. How loss of tooth structure impacts the biomechanical behavior of a single-rooted maxillary premolar: FEA. Odontology 2024; 112:279-286. [PMID: 37394683 PMCID: PMC10776703 DOI: 10.1007/s10266-023-00829-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 06/15/2023] [Indexed: 07/04/2023]
Abstract
To evaluate the influence of the loss of coronal and radicular tooth structure on the biomechanical behavior and fatigue life of an endodontically treated maxillary premolar with confluent root canals using finite element analysis (FEA). An extracted maxillary second premolar was scanned to produce intact (IT) 3D model. Models were designed with an occlusal conservative access cavity (CAC) with different coronal defects; mesial defect (MO CAC), occlusal, mesial and distal defect (MOD CAC), and 2 different root canal preparations (30/.04, and 40/.04) producing 6 experimental models. FEA was used to study each model. A simulation of cycling loading of 50N was applied occlusally to stimulate the normal masticatory force. Number of cycles till failure (NCF) was used to compare strength of different models and stress distribution patterns via von Mises (vM) and maximum principal stress (MPS). The IT model survived 1.5 × 1010 cycles before failure, the CAC-30.04 had the longest survival of 1.59 × 109, while the MOD CAC-40.04 had the shortest survival of 8.35 × 107 cycles till failure. vM stress analysis showed that stress magnitudes were impacted by the progressive loss of coronal tooth structure rather than the radicular structure. MPS analysis showed that significant loss of coronal tooth structure translates into more tensile stresses. Given the limited size of maxillary premolars, marginal ridges have a critical role in the biomechanical behavior of the tooth. Access cavity preparation has a much bigger impact than radicular preparation on their strength and life span.
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Affiliation(s)
- Roaa Abdelwahab Abdelfattah
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Misr-Ismalia Road, El Sherouk City, Cairo, 11837, Egypt.
| | - Nawar Naguib Nawar
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Misr-Ismalia Road, El Sherouk City, Cairo, 11837, Egypt
| | - Engy M Kataia
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Misr-Ismalia Road, El Sherouk City, Cairo, 11837, Egypt
| | - Shehabeldin Mohamed Saber
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Misr-Ismalia Road, El Sherouk City, Cairo, 11837, Egypt
- Department of Endodontics, Ain Shams University, Cairo, Egypt
- Centre for Innovative Dental Sciences (CIDS), Faculty of Dentistry, The British University in Egypt (BUE), El Sherouk City, 11837, Egypt
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Galal DY, Nawar NN, Abou El Seoud M, Saber SM, Kim HC. Options for Access Cavity Designs of Mandibular Incisors: Mechanical Aspects from Finite Element Study. J Endod 2023; 49:1706-1712. [PMID: 37802135 DOI: 10.1016/j.joen.2023.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/14/2023] [Accepted: 09/27/2023] [Indexed: 10/08/2023]
Abstract
INTRODUCTION This study investigated different access cavity designs of mandibular anteriors in terms of their effect on the biomechanical behavior and longevity using finite element analysis (FEA). METHODS A 3-dimensional model of a mandibular incisor was created for FEA. After validating the intact tooth (IT) model, 4 experimental models were developed (traditional lingual access cavity [TLA], facial access cavity [FAC], incisal access cavity [ICA], and cervical access cavity [CVA]). Cyclic loading was simulated, and the number of cycles until failure (NCF) was compared to the IT model. Stress distribution patterns, maximum von Mises stresses (vMSs), and maximum principal stresses (MPSs) were analyzed mathematically. The safety factor was also calculated and demonstrated. RESULTS The maximum vMS registered on the IT model was 134.16 MPa. The FCA and the CVA provided the highest NCF (193.7% compared with the IT model) followed by ICA (58.2%) and TLA (21.4%). The vM and MPS analysis revealed that the lingual surface is a primary stress channel, and the presence of an access cavity significantly weakens the tooth structure. Although the maximum vMS registered for the IT model was 134.16 MPa, the maximum vMS was 73.97 MPa for both the FCA and the CVA, 152.27 MPa for the ICA, and 173.63 MPa for the TLA. CONCLUSIONS The facial and cervical access cavity designs provided considerable reinforcement to the endodontically treated mandibular incisors. With advancements in esthetic restorative materials and endodontic instruments, facial access design could emerge as the new standard for access cavity preparation in mandibular incisors.
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Affiliation(s)
- Dina Yehia Galal
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt
| | - Nawar Naguib Nawar
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt
| | - Mohammed Abou El Seoud
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt
| | - Shehabeldin Mohamed Saber
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt; Center for Innovative Dental Sciences, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt; Department of Endodontics, Ain Shams University, Cairo, Egypt.
| | - Hyeon-Cheol Kim
- Department of Conservative Dentistry, Pusan National University School of Dentistry, Dental Research Institute, Dental and Life Science Institute, Yangsan, Korea.
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De Roo NMC, Toulouse K, Thierens LAM, Henry S, De Buyser S, Temmerman L, Verbeeck RMH, De Pauw GAM. In Vitro Investigation into the Effect of Cryopreservation on the Mechanical Characteristics of Dental Hard Tissues. J Funct Biomater 2023; 14:551. [PMID: 37998120 PMCID: PMC10672544 DOI: 10.3390/jfb14110551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/25/2023] Open
Abstract
Previous research has reported on hidden damage within the dentin introduced by cryopreservation, but the effect on the mechanical properties of the hard tissues at tooth level remains unclear. The main objective of this study is to investigate the effect of cryopreservation on the mechanical properties of teeth. A matched sample of 234 premolars of 117 children (9 ≤ age ≤ 16 years), bilaterally extracted for orthodontic reasons, were included. For each child, one tooth was randomly allocated to the cryopreservation group and the contralateral tooth was assigned to the control group. Static compression tests were performed to determine load to failure, stiffness, and toughness. In a subgroup of 20 teeth, a cyclic preloading or chewing simulation was performed. Additionally, the fracture mode was determined, and the microstructure of the fractured surfaces was examined using a scanning electron microscope (SEM). Linear mixed model analyses could not detect a statistical difference in the mean load to failure (p = 0.549), mean toughness (p = 0.968), or mean stiffness (p = 0.150) between cryopreserved and non-cryopreserved teeth. No significant difference in load to failure after cyclic preloading was detected between groups (p = 0.734). SEM analysis revealed comparable fracture characteristics between groups. It is concluded that cryopreservation does not affect the mean load to failure, stiffness, or toughness of teeth, indicating that hidden damage in the dentin is not critical at tooth level.
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Affiliation(s)
- Noëmi M. C. De Roo
- Oral Health Sciences, Department of Orthodontics, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium (L.A.M.T.); (G.A.M.D.P.)
| | - Kaat Toulouse
- Oral Health Sciences, Department of Orthodontics, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium (L.A.M.T.); (G.A.M.D.P.)
| | - Laurent A. M. Thierens
- Oral Health Sciences, Department of Orthodontics, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium (L.A.M.T.); (G.A.M.D.P.)
- Translational Neurosciences, Department of Cranio-Maxillofacial Surgery, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
| | - Silke Henry
- Laboratory of Pharmaceutical Technology, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Stefanie De Buyser
- Biostatistics Unit, Faculty of Medicine and Health Sciences, Ghent University, C. Heymanslaan 10, 9000 Ghent, Belgium;
| | - Liesbeth Temmerman
- Oral Health Sciences, Department of Orthodontics, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium (L.A.M.T.); (G.A.M.D.P.)
| | - Ronald M. H. Verbeeck
- Biomaterials Group, Department of Basic Medical Sciences, Ghent University, C. Heymanslaan 10, 9000 Ghent, Belgium
| | - Guy A. M. De Pauw
- Oral Health Sciences, Department of Orthodontics, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium (L.A.M.T.); (G.A.M.D.P.)
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Nawar NN, Abdelfattah RA, Kataia M, Saber SM, Kataia EM, Kim HC. Effect of Proximal Caries-driven Access on the Biomechanical Behavior of Endodontically Treated Maxillary Premolars. J Endod 2023; 49:1337-1343. [PMID: 37517584 DOI: 10.1016/j.joen.2023.07.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 08/01/2023]
Abstract
INTRODUCTION This study investigated the effects from the carious cavity and access from it on the fracture resistance of endodontically treated maxillary premolars using finite element analysis (FEA). METHODS A maxillary premolar was used to compare 3 types of access cavity related to having a proximal carious defect: caries-driven access (CDA), conservative access that has a mesial component (MCA), as well as traditional access with the same mesial component (MTA). Cyclic loading was simulated on the occlusal surface, and number of cycles until failure (NCF) was compared with the intact tooth model (IT). Mathematical analysis was done to evaluate the stress distribution patterns and calculated maximum von Mises (vM) and maximum principal stresses (MPS), with emphasis on pericervical region as a specific area of interest. RESULTS Maximum vM registered on the IT was 6.14 MPa. CDA provided the highest NCF with 92.28% of the IT, followed by MCA (84.90%) and MTA (83.79%). The vM and MPS analysis showed that the stress values and patterns are affected more by the proximity of the occlusal load to the tooth/restoration interface. Concerning the pericervical region, maximum vM was registered for IT (4.11 MPa), followed by CDA (4.85 MPa) and then MCA (8.13 MPa) and MTA (8.61 MPa), whereas the MPS analysis revealed that CDA showed the highest magnitude of tensile stresses. CONCLUSIONS A proximal CDA benefits the mechanical properties of maxillary premolars; however, its impact on the biological aspect should be assessed to provide a ruling for/against it.
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Affiliation(s)
- Nawar Naguib Nawar
- Department of Endodontics, Faculty of Dentistry, British University in Egypt (BUE), El Sherouk City, Egypt
| | | | - Mohamed Kataia
- Department of Endodontics, Faculty of Dentistry, British University in Egypt (BUE), El Sherouk City, Egypt
| | - Shehabeldin Mohamed Saber
- Department of Endodontics, Faculty of Dentistry, British University in Egypt (BUE), El Sherouk City, Egypt; Center for Innovative Dental Sciences (CIDS), Faculty of Dentistry, British University in Egypt (BUE), El Sherouk City, Egypt; Department of Endodontics, Ain Shams University, Cairo, Egypt
| | - Engy Medhat Kataia
- Department of Endodontics, Faculty of Dentistry, British University in Egypt (BUE), El Sherouk City, Egypt; Restorative and Dental Materials Department, National Research Centre, Doki, Egypt.
| | - Hyeon-Cheol Kim
- Department of Conservative Dentistry, Pusan National University School of Dentistry, Dental Research Institute, Dental and Life Science Institute, Yangsan, Korea.
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Nawar NN, Elkholy MMA, Ha WN, Saber SM, Kim HC. Optimum shaping parameters of the middle mesial canal in mandibular first molars: A finite element analysis study. J Endod 2023; 49:567-574. [PMID: 36965769 DOI: 10.1016/j.joen.2023.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/27/2023] [Accepted: 03/17/2023] [Indexed: 03/27/2023]
Abstract
INTRODUCTION This study investigated the effect of shaping parameters of two different configurations of middle mesial canals (MMC) on the biomechanical behavior and life span of a mandibular first molar using finite element analysis (FEA). METHODS A mandibular molar with an independent MMC and another with a confluent MMC were scanned via micro-CT, and FEA models were produced. For each tooth, an intact model and 5 experimental models were produced differed by parameters of how MMC was shaped: unshaped MMC, 25/.04, 25/.06, 30/.04, and 30/.06. Cyclic loading of 50 N was applied on the occlusal surface in vertical and oblique scenarios, and the number of cycles until failure (NCF) was compared to the intact models. In addition, mathematical analyses evaluated the stress distribution patterns and calculated maximum von Mises and maximum principal stresses. RESULTS For both the independent and confluent MMC models, shaping the MMC reduced the NCF. The lifelog percentage of models was inversely proportional with radicular shaping parameters during the vertical and oblique loading scenarios. The shaping size of 30/.06 resulted in lower lifelog percentage than the cases with shaping size of 25/.04 in both of the independent and confluent MMC models. For all models, oblique loading reduced NCF more than vertical loading. CONCLUSION Shaping the MMC should be kept as conservative as 25/.04. Also, whether the MMC is independent or confluent is a deciding factor in whether to increase the apical diameter or the root canal taper when larger shaping parameters are needed.
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Affiliation(s)
- Nawar Naguib Nawar
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt
| | - Mostafa M A Elkholy
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt; School of Dentistry, University of Western Australia, Perth, WA, Australia
| | - William Nguyen Ha
- Department of Endodontics, Sydney Dental School, University of Sydney
| | - Shehabeldin Mohamed Saber
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt; Department of Endodontics, Ain Shams University, Cairo, Egypt.
| | - Hyeon-Cheol Kim
- Department of Conservative Dentistry, Pusan National University School of Dentistry, Dental Research Institute, Dental and Life Science Institute, Yangsan, Korea.
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Kruzic JJ, Hoffman M, Arsecularatne JA. Fatigue and wear of human tooth enamel: A review. J Mech Behav Biomed Mater 2023; 138:105574. [PMID: 36473402 DOI: 10.1016/j.jmbbm.2022.105574] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/14/2022] [Accepted: 11/15/2022] [Indexed: 11/21/2022]
Abstract
Human tooth enamel must withstand the cyclic contact forces, wear, and corrosion processes involved with typical oral functions. Furthermore, unlike other human tissues, dental enamel does not have a significant capacity for healing or self-repair and thus the longevity of natural teeth in the oral environment depends to a large degree on the fatigue and wear properties of enamel. The purpose of this review is to provide an overview of our understanding of the fatigue and wear mechanisms of human enamel and how they relate to in vivo observations of tooth damage in the complex oral environment. A key finding of this review is that fatigue and wear processes are closely related. For example, the presence of abrasive wear particles significantly lowers the forces needed to initiate contact fatigue cracking while subsurface fatigue crack propagation drives key delamination wear mechanisms during attrition or attrition-corrosion of enamel. Furthermore, this review seeks to bring a materials science and mechanical engineering perspective to fatigue and wear phenomena. In this regard, we see developing a mechanistic description of fatigue and wear, and understanding the interconnectivity of the processes, as essential for successfully modelling enamel fatigue and wear damage and developing strategies and treatments to improve the longevity of our natural teeth. Furthermore, we anticipate that this review will stimulate ideas for extending the lifetime of the natural tooth structure and will help highlight where our understanding is too limited and where additional research into fatigue and wear of human tooth enamel is warranted.
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Affiliation(s)
- Jamie J Kruzic
- School of Mechanical and Manufacturing Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia.
| | - Mark Hoffman
- School of Engineering, University of Newcastle, Callaghan NSW 2308, Australia; School of Materials Science and Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia
| | - Joseph A Arsecularatne
- School of Mechanical and Manufacturing Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia
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Wang D, Han S, Yang M. Tooth Diversity Underpins Future Biomimetic Replications. Biomimetics (Basel) 2023; 8:biomimetics8010042. [PMID: 36810373 PMCID: PMC9944091 DOI: 10.3390/biomimetics8010042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/14/2023] [Accepted: 01/15/2023] [Indexed: 01/20/2023] Open
Abstract
Although the evolution of tooth structure seems highly conserved, remarkable diversity exists among species due to different living environments and survival requirements. Along with the conservation, this diversity of evolution allows for the optimized structures and functions of teeth under various service conditions, providing valuable resources for the rational design of biomimetic materials. In this review, we survey the current knowledge about teeth from representative mammals and aquatic animals, including human teeth, herbivore and carnivore teeth, shark teeth, calcite teeth in sea urchins, magnetite teeth in chitons, and transparent teeth in dragonfish, to name a few. The highlight of tooth diversity in terms of compositions, structures, properties, and functions may stimulate further efforts in the synthesis of tooth-inspired materials with enhanced mechanical performance and broader property sets. The state-of-the-art syntheses of enamel mimetics and their properties are briefly covered. We envision that future development in this field will need to take the advantage of both conservation and diversity of teeth. Our own view on the opportunities and key challenges in this pathway is presented with a focus on the hierarchical and gradient structures, multifunctional design, and precise and scalable synthesis.
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Pedroso CM, Normando AGC, Pérez-de-Oliveira ME, Palmier NR, Guerra ENS, Epstein JB, Lopes MA, Ribeiro ACP, Brandão TB, Bensadoun RJ, Marta GN, de Goes MF, Santos-Silva AR. Dosimetric parameters and radiotherapy simulation methods used in preclinical studies of radiation damage to the dentition: a systematic review. Oral Surg Oral Med Oral Pathol Oral Radiol 2022; 135:614-625. [PMID: 36725442 DOI: 10.1016/j.oooo.2022.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/19/2022] [Accepted: 12/15/2022] [Indexed: 12/25/2022]
Abstract
OBJECTIVE This systematic review investigated the dosimetric parameters used in preclinical studies. STUDY DESIGN Searches were performed in 3 databases (PubMed, Scopus, and Embase) and gray literature to identify studies for review. In vitro and ex vivo studies that examined the effect of radiation on human permanent teeth were included. The modified Consolidated Standards Of Reporting Trials checklist of items for reporting preclinical in vitro studies was used to assess the risk of bias. RESULTS In total, 32 studies met the inclusion criteria. The average radiation dose of in vitro studies was 53 (±22) Gy and in ex vivo studies was 69 (±1) Gy. Twenty-two studies used 5 different fractionation schemes. Twenty-two of the included studies did not report the radiotherapy modality of those reporting. Twenty studies used linear accelerators, and 7 used Cobalt-60 with the source-surface-distance of radiation ranging from 1.5 to 100 cm. Distilled water was the storage solution for the dental structure used most commonly. Biases were observed, including small sample sizes, lack of randomization, and blinding processes. CONCLUSION The dosimetric parameters used in the preclinical studies, including radiation dose, radiotherapy modality, fractionation regime, and the storage solutions used did not support the hypothesis of direct effects of radiation on the dental structure.
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Affiliation(s)
- Caique Mariano Pedroso
- Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | - Ana Gabriela Costa Normando
- Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | | | - Natália Rangel Palmier
- Serviço de Odontologia Oncológica, Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Eliete Neves Silva Guerra
- Laboratory of Oral Histopathology, Health Sciences Faculty, University of Brasília (UnB), Brasília, Brazil
| | - Joel B Epstein
- Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA; City of Hope Comprehensive Cancer Center, Duarte, CA, USA
| | - Marcio Ajudarte Lopes
- Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | - Ana Carolina Prado Ribeiro
- Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil; Serviço de Odontologia Oncológica, Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Thaís Bianca Brandão
- Serviço de Odontologia Oncológica, Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | | | | | - Mario Fernando de Goes
- Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | - Alan Roger Santos-Silva
- Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil.
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Dorado S, Arias A, Jimenez-Octavio JR. Biomechanical Modelling for Tooth Survival Studies: Mechanical Properties, Loads and Boundary Conditions-A Narrative Review. MATERIALS (BASEL, SWITZERLAND) 2022; 15:7852. [PMID: 36363451 PMCID: PMC9657341 DOI: 10.3390/ma15217852] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/02/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Recent biomechanical studies have focused on studying the response of teeth before and after different treatments under functional and parafunctional loads. These studies often involve experimental and/or finite element analysis (FEA). Current loading and boundary conditions may not entirely represent the real condition of the tooth in clinical situations. The importance of homogenizing both sample characterization and boundary conditions definition for future dental biomechanical studies is highlighted. The mechanical properties of dental structural tissues are presented, along with the effect of functional and parafunctional loads and other environmental and biological parameters that may influence tooth survival. A range of values for Young's modulus, Poisson ratio, compressive strength, threshold stress intensity factor and fracture toughness are provided for enamel and dentin; as well as Young's modulus and Poisson ratio for the PDL, trabecular and cortical bone. Angles, loading magnitude and frequency are provided for functional and parafunctional loads. The environmental and physiological conditions (age, gender, tooth, humidity, etc.), that may influence tooth survival are also discussed. Oversimplifications of biomechanical models could end up in results that divert from the natural behavior of teeth. Experimental validation models with close-to-reality boundary conditions should be developed to compare the validity of simplified models.
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Affiliation(s)
- Saúl Dorado
- Department of Mechanical Engineering, Escuela Técnica Superior de Ingeniería ICAI, Universidad Pontificia Comillas, 28015 Madrid, Spain
| | - Ana Arias
- Department of Conservative and Prosthetic Dentistry, School of Dentistry, Complutense University, 28040 Madrid, Spain
| | - Jesus R. Jimenez-Octavio
- Instituto de Investigación Tecnológica, Escuela Técnica Superior de Ingeniería ICAI, Universidad Pontificia Comillas, 28015 Madrid, Spain
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Guatelli‐Steinberg D, Schwartz GT, O'Hara MC, Gurian K, Rychel J, McGraw WS. Molar form, enamel growth, and durophagy in Cercocebus and Lophocebus. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 179:386-404. [PMCID: PMC9796247 DOI: 10.1002/ajpa.24592] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 06/20/2022] [Accepted: 06/29/2022] [Indexed: 05/29/2023]
Abstract
Objectives To test the hypothesis that differences in crown structure, enamel growth, and crown geometry in Cercocebus and Lophocebus molars covary with differences in the feeding strategies (habitual vs. fallback durophagy, respectively) of these two genera. Relative to Lophocebus molars, Cercocebus molars are predicted to possess features associated with greater fracture resistance and to differ in enamel growth parameters related to these features. Materials and Methods Sample proveniences are as follows: Cercocebus atys molars are from the Taï Forest, Ivory Coast; Lophocebus albigena molars are from a site north of Makoua, Republic of Congo; and a Lophocebus atterimus molar is from the Lomako Forest, Democratic Republic of Congo. For μCT scans on which aspects of molar form were measured, sample sizes ranged from 5 to 35 for Cercocebus and 3 to 12 for Lophocebus. A subsample of upper molars was physically sectioned to measure enamel growth variables. Results Partly as a function of their larger size, Cercocebus molars had significantly greater absolute crown strength (ACS) than Lophocebus molars, supporting the hypothesis. Greater crown heights in Cercocebus are achieved through faster enamel extension rates. Also supporting the hypothesis, molar flare and proportional occlusal basin enamel thickness were significantly greater in Cercocebus. Relative enamel thickness (RET), however, was significantly greater in Lophocebus. Discussion If ACS is a better predictor of fracture resistance than RET, then Cercocebus molars may be more fracture resistant than those of Lophocebus. Greater molar flare and proportional occlusal basin thickness might also afford Cercocebus molars greater fracture resistance.
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Affiliation(s)
| | - Gary T. Schwartz
- School of Human Evolution and Social Change and Institute of Human OriginsArizona State UniversityTempeArizonaUSA
| | - Mackie C. O'Hara
- Department of AnthropologyThe Ohio State UniversityColumbusOhioUSA
- School of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Kaita Gurian
- Department of AnthropologyThe Ohio State UniversityColumbusOhioUSA
| | - Jess Rychel
- Department of AnthropologyThe Ohio State UniversityColumbusOhioUSA
| | - W. Scott McGraw
- Department of AnthropologyThe Ohio State UniversityColumbusOhioUSA
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Hunter-Schreger Band configuration in human molars reveals more decussation in the lateral enamel of 'functional' cusps than 'guiding' cusps. Arch Oral Biol 2022; 142:105524. [PMID: 36029738 DOI: 10.1016/j.archoralbio.2022.105524] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 08/11/2022] [Accepted: 08/15/2022] [Indexed: 11/21/2022]
Abstract
OBJECTIVES Enamel prism decussation, which manifests as Hunter-Schreger Bands (HSB), is considered a mechanism to mitigate crack propagation. During the chewing cycle, the 'functional' cusps that are involved in Phase II crushing and grinding experience more complex patterns of stress than do those that 'guide' the molars into occlusion (Phase I). This study examines HSB configuration in the lateral enamel of human molars to identify potential differences between these cusps as predicted from their functional distinctions. DESIGN Measurements were recorded from scanning electron micrographs of sections through the mesial cusps of unworn permanent molars. For each section, HSB packing density and the relative thickness of decussated enamel were quantified in the cuspal and middle segments of lateral enamel over the guiding and functional cusps. RESULTS No clear trend from first to third molars in HSB configuration was found in either jaw. In maxillary molars, the functional cusp displays higher HSB packing density in the cuspal and middle segments, and relatively thicker decussated enamel in the cuspal segment than does the guiding cusp. In mandibular molars, the functional cusp displays higher HSB packing density in the middle segment than does the guiding cusp, but no difference in relative thickness was found between them. Enamel of mandibular molars shows weaker decussation than maxillary molars. CONCLUSIONS The results suggest that guiding cusps are intrinsically more susceptible to crack propagation than functional cusps in human permanent molars. Structural factors such as enamel decussation should be considered when interpreting enamel chipping patterns in dietary contexts.
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Nawar NN, Kataia M, Omar N, Kataia EM, Kim HC. Biomechanical behavior and life span of maxillary molar according to the access preparation and pericervical dentin preservation: finite element analysis. J Endod 2022; 48:902-908. [DOI: 10.1016/j.joen.2022.03.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 03/29/2022] [Accepted: 03/31/2022] [Indexed: 10/18/2022]
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13
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Paranthropus robustus tooth chipping patterns do not support regular hard food mastication. J Hum Evol 2021; 158:103044. [PMID: 34303928 DOI: 10.1016/j.jhevol.2021.103044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 06/03/2021] [Accepted: 06/08/2021] [Indexed: 11/22/2022]
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14
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Chen J, Jian Y, Chen S, Wang X, Dao L, Zhao K. Establishment of optimal variable elastic modulus distribution in the design of full-crown restorations by finite element analysis. Dent Mater J 2021; 40:1403-1409. [PMID: 34261832 DOI: 10.4012/dmj.2021-053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To establish optimal elastic modulus distribution throughout the entire all-ceramic crown, aiming at improvement of the mechanical properties of the restoration as well as the adhesive interface, seven 3D models of mandibular first premolars of zirconia monolithic and bilayer crowns and lithium disilicate monolithic and bilayer crowns were constructed. The elastic modulus distribution of 8-layer crown A referred to human enamel, B was calculated by a genetic algorithm (GA) to minimize the principle stresses on the crown, and C minimized the shear stresses at the cementing lines. After applying a static load of 600 N, the maximum principle stresses were calculated and analyzed by finite element analysis (FEA). Group C were found to have the lowest peak shear stress at the cementing line and moderate peak tensile stress in the crown. Introduction of the modified elastic modulus distribution from human enamel into the entire all-ceramic crown reinforces the mechanical properties of the whole restoration as well as the adhesive interface against chipping and debonding.
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Affiliation(s)
- Jianghai Chen
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University
| | - Yutao Jian
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University.,Institute of Stomatological Research, Sun Yat-sen University
| | - Shumin Chen
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University
| | - Xiaodong Wang
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University
| | - Li Dao
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University
| | - Ke Zhao
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University
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15
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Elkholy MMA, Nawar NN, Ha WN, Saber SM, Kim HC. Impact of Canal Taper and Access Cavity Design on the Life Span of an Endodontically Treated Mandibular Molar: A Finite Element Analysis. J Endod 2021; 47:1472-1480. [PMID: 34139264 DOI: 10.1016/j.joen.2021.06.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/05/2021] [Accepted: 06/08/2021] [Indexed: 12/27/2022]
Abstract
INTRODUCTION This study investigated the impact of different canal tapers and access cavity designs on the life span of endodontically treated mandibular first molars using the finite element method. METHODS Finite element analysis was performed on simulated models with 3 access cavity designs (traditional, conservative, and truss). The mesial canals were prepared to either constant tapers of 25/.04 and 25/.06 or a variable taper corresponding to the cumulative canal preparation shapes of TruNatomy Prime (Dentsply Sirona, Charlotte, NC) and ProTaper Gold F2 (Dentsply Sirona). The distal canals in all models had a 40/.04 preparation. Using occlusal fingerprint analysis, all models were subjected to cyclic occlusal loading until model failure. The number of cycles until failure, the location of failure, stress distribution patterns, and the maximum von Mises stresses were assessed. RESULTS The traditional access models showed a lower life span than the conservative and truss models regardless of the canal taper, whereas there was not a notable difference in the conservative and truss models. The stresses migrated apically along the root surface and remarkably on the mesial aspect of the mesial root and the furcation area's outer surface. After root canal preparation with different tapers, there were no evident changes in the pattern and magnitude of the stresses distributed along the root surface. CONCLUSIONS The life span of the tooth is affected more significantly by the access cavity design than the root canal preparation taper. Because stress patterns migrate apically rather than concentrate in the pericervical area, crack initiation and propagation might occur anywhere on the root surface.
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Affiliation(s)
- Mostafa M A Elkholy
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt.
| | - Nawar Naguib Nawar
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt
| | - William Nguyen Ha
- University of Adelaide, Adelaide Dental School, Adelaide, South Australia, Australia
| | - Shehabeldin Mohamed Saber
- Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt; Department of Endodontics, Ain Shams University, Cairo, Egypt
| | - Hyeon-Cheol Kim
- Department of Conservative Dentistry, Pusan National University School of Dentistry, Dental Research Institute, Dental and Life Science Institute, Gyeongnam, Korea.
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16
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Towle I, Irish JD, De Groote I, Fernée C, Loch C. Dental caries in South African fossil hominins. S AFR J SCI 2021. [DOI: 10.17159/sajs.2021/8705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Once considered rare in fossil hominins, caries has recently been reported in several hominin species, requiring a new assessment of this condition during human evolution. Caries prevalence and location on the teeth of South African fossil hominins were observed and compared with published data from other hominin samples. Teeth were viewed macroscopically, with lesion position and severity noted and described. For all South African fossil hominin specimens studied to date, a total of 10 carious teeth (14 lesions), including 4 described for the first time here, have been observed. These carious teeth were found in a minimum of seven individuals, including five Paranthropus robustus, one early Homo, and one Homo naledi. All 14 lesions affected posterior teeth. The results suggest cariogenic biofilms and foods may have been present in the oral environment of a wide variety of hominins. Caries prevalence in studied fossil hominins is similar to those in pre-agricultural human groups, in which 1–5% of teeth are typically affected.
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Affiliation(s)
- Ian Towle
- Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand
| | - Joel D. Irish
- Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University, Liverpool, United Kingdom
- Evolutionary Studies Institute and Centre for Excellence in PaleoSciences, University of the Witwatersrand, Johannesburg, South Africa
| | | | - Christianne Fernée
- Department of Anthropology and Archaeology, University of Bristol, Bristol, United Kingdom
- Department of Archaeology, University of Southampton, Southampton, United Kingdom
| | - Carolina Loch
- Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand
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Chipping and wear patterns in extant primate and fossil hominin molars: 'Functional' cusps are associated with extensive wear but low levels of fracture. J Hum Evol 2020; 151:102923. [PMID: 33360110 DOI: 10.1016/j.jhevol.2020.102923] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 01/01/2023]
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18
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Ijbara M, Wada K, Wada J, Jayawardena JA, Miyashin M. Replica-based inspection of enamel wear microfeatures. Biomed Mater Eng 2020; 31:279-290. [PMID: 32986650 DOI: 10.3233/bme-206006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Surface replication is a nondestructive evaluation technique applied in examining surface wear by recording surface irregularities, especially in conditions when surfaces of interest cannot be further manipulated to fit directly under a microscope to be examined. Enamel is the outermost protective layer of the human teeth and is constantly stressed by mastication forces which results in enamel wear. OBJECTIVE To date, a procedure combining the clinical and microscopic examination of enamel surfaces is absent, which hinders the early diagnosis and comprehension of the wear process. METHODS This study investigated the role of replication sheets in registering microscopic wear on human enamel surfaces by both negative and positive replication techniques. RESULTS The sheets replicated wear features successfully. Sheets were compatible to use with multiple microscopes, with proper preparation, including high resolution microscopes such as the scanning electron microscope and transmitting electron microscope.
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Affiliation(s)
- Manhal Ijbara
- Pediatric Dentistry Department, Division of Oral Restitution, Graduate School, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan.,Ministry of Health, Ha'il Dental Center and King Khalid Hospital, Ha'il, Kingdom of Saudi Arabia
| | - Kanae Wada
- Pediatric Dentistry Department, Division of Oral Restitution, Graduate School, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan
| | - Junichiro Wada
- Department of Removable Partial Prosthodontics, Graduate School, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan
| | - Jayanetti Asiri Jayawardena
- Department of General Education, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama, Japan
| | - Michiyo Miyashin
- Pediatric Dentistry Department, Division of Oral Restitution, Graduate School, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan
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19
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Borrero-Lopez O, Constantino PJ, Bush MB, Lawn BR. On the vital role of enamel prism interfaces and graded properties in human tooth survival. Biol Lett 2020; 16:20200498. [PMID: 32842897 DOI: 10.1098/rsbl.2020.0498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Teeth of omnivores face a formidable evolutionary challenge: how to protect against fracture and abrasive wear caused by the wide variety of foods they process. It is hypothesized that this challenge is met in part by adaptations in enamel microstructure. The low-crowned teeth of humans and some other omnivorous mammals exhibit multiple fissures running longitudinally along the outer enamel walls, yet remain intact. It is proposed that inter-prism weakness and enamel property gradation act together to avert entry of these fissures into vulnerable inner tooth regions and, at the same time, confer wear resistance at the occlusal surface. A simple indentation experiment is employed to quantify crack paths and energetics in human enamel, and an extended-finite-element model to evaluate longitudinal crack growth histories. Consideration is given as to how tooth microstructure may have played a vital role in human evolution, and by extension to other omnivorous mammals.
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Affiliation(s)
- Oscar Borrero-Lopez
- Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, 06006 Badajoz, Spain
| | - Paul J Constantino
- Department of Biology, Saint Michael's College, Colchester, VT 05439, USA
| | - Mark B Bush
- Department of Mechanical Engineering, University of Western Australia, Crawley, WA 6009, Australia
| | - Brian R Lawn
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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20
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Wilmers J, Bargmann S. Nature's design solutions in dental enamel: Uniting high strength and extreme damage resistance. Acta Biomater 2020; 107:1-24. [PMID: 32087326 DOI: 10.1016/j.actbio.2020.02.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/07/2020] [Accepted: 02/12/2020] [Indexed: 02/06/2023]
Abstract
The most important demand of today's high-performance materials is to unite high strength with extreme fracture toughness. The combination of withstanding large forces (strength) and resistance to fracture (toughness), especially preventing catastrophic material failure by cracking, is of utmost importance when it comes to structural applications of these materials. However, these two properties are commonly found to be mutually exclusive: strong materials are brittle and tough materials are soft. In dental enamel, nature has combined both properties with outstanding success - despite a limited number of available constituents. Made up of brittle mineral crystals arranged in a sophisticated hierarchical microstructure, enamel exhibits high stiffness and excellent toughness. Different species exhibit a variety of structural adaptations on varying scales in their dental enamel which optimise not only fracture toughness, but also hardness and abrasion behaviour. Nature's materials still outperform their synthetic counterparts due to these complex structure-property relationships that are not yet fully understood. By analysing structure variations and the underlying mechanical mechanisms systematically, design principles which are the key for the development of advanced synthetic materials uniting high strength and toughness can be formulated. STATEMENT OF SIGNIFICANCE: Dental enamel is a hard protective tissue that combines high strength with an exceptional resistance to catastrophic fracture, properties that in classical materials are commonly found to be mutually exclusive. The biological material is able to outperform its synthetic counterparts due to a sophisticated hierarchical microstructure. Between different species, microstructural adaptations can vary significantly. In this contribution, the different types of dental enamel present in different species are reviewed and connections between microstructure and (mechanical) properties are drawn. By consolidating available information for various species and reviewing it from a materials science point of view, design principles for the development of advanced biomimetic materials uniting high strength and toughness can be formulated.
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21
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Angermair J, Nolte D, Linsenmann R, Kunzelmann KH. The influence of storage temperature on fracture behavior of cryopreserved teeth-An in vitro study. Clin Exp Dent Res 2020; 6:373-380. [PMID: 32222040 PMCID: PMC7301388 DOI: 10.1002/cre2.283] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/17/2020] [Accepted: 02/23/2020] [Indexed: 11/20/2022] Open
Abstract
Objectives Cryopreservation is discussed as a viable method of preserving teeth for determined autogenous tooth transplantation. Unchanged physical properties of hard tooth tissues are crucial for functional healing. Due to different thermal expansion coefficients of enamel and dentin or the crystallization process, the freezing process may lead to crack formation, which could adversely impact the long‐term prognosis of the teeth. Material and methods Twenty third molars (n = 20) were frozen slowly using a conservative cryopreservation protocol and stored at −80°C (group 1) and −196°C (group 2). After a storage time of 2 weeks, the samples were thawed to a temperature of +36°C and embedded in polymethyl methacrylate blocks. Cyclic loading was carried out using a spherical steel test specimen with 50,000 mechanical load cycles, followed by load to failure testing for determination of critical load. Results No significant difference in the first load drop could be detected during the load to failure test under different storage conditions. The values until fracture correlated very closely in contralateral tooth pairs, which emphasizes the importance of crown geometry in load to failure tests. Conclusions Conclusions: Cryopreservation, specifically the storage temperature, does not appear to have a significant effect on the physical properties of tooth transplants.
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Affiliation(s)
- Johannes Angermair
- Clinic of Oral- and Maxillofacial Surgery, Translational Implantology, Medical Center Freiburg - Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Dirk Nolte
- Private Practice for Oral and Maxillofacial Surgery, Munich, Germany
| | - Robert Linsenmann
- Private Practice for Oral and Maxillofacial Surgery, Munich, Germany
| | - Karl-Heinz Kunzelmann
- Department of Conservative Dentistry and Parodontology, University Medical Center Munich, Munich, Germany
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22
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Contact damage of human dental enamel under cyclic axial loading with abrasive particles. J Mech Behav Biomed Mater 2020; 102:103512. [DOI: 10.1016/j.jmbbm.2019.103512] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 10/25/2019] [Accepted: 10/28/2019] [Indexed: 12/28/2022]
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23
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Thompson VP. The tooth: An analogue for biomimetic materials design and processing. Dent Mater 2020; 36:25-42. [DOI: 10.1016/j.dental.2019.08.106] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 08/21/2019] [Accepted: 08/28/2019] [Indexed: 01/05/2023]
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24
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Hilton TJ, Funkhouser E, Ferracane JL, Gilbert GH, Gordan VV, Bennett S, Bone J, Richardson PA, Malmstrom H. Symptom changes and crack progression in untreated cracked teeth: One-year findings from the National Dental Practice-Based Research Network. J Dent 2019; 93:103269. [PMID: 31899264 DOI: 10.1016/j.jdent.2019.103269] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 12/27/2019] [Accepted: 12/28/2019] [Indexed: 01/10/2023] Open
Abstract
OBJECTIVES The study objective was to: (1) quantify symptom (pain) and crack changes during one year of follow-up, among teeth that had at least one visible crack at baseline but which did not receive treatment for those cracks; (2) identify any patient traits/behaviors and external tooth/crack characteristics correlated with these changes. METHODS In this observational study, 209 National Dental Practice-Based Research Network dentists enrolled a convenience sample of 2858 subjects, each with a single, vital posterior tooth with at least one observed external crack; 1850 teeth remained untreated after one year of follow-up and were the cohort for analyses. Data were collected at the patient-, tooth-, and crack-level at baseline, one-year follow up (Y1), and interim visits. Associations between changes in symptoms and cracks were identified, as were changes in symptoms associated with baseline treatment recommendations. RESULTS Changes in pain symptoms were observed in 32% of patients; decreases were twice as common as increases (23% vs. 10%). More changes were observed in cold pain than in biting pain and spontaneous pain combined; 2% had increases in biting pain and 2% in spontaneous pain. Only 6% had an increase in the number of cracks. Changes in pain symptoms were not associated with an increase in the number of cracks, but were associated with baseline treatment recommendations. Specifically, pain symptom changes (especially decreases) were more common when the tooth was recommended for treatment at baseline. CONCLUSIONS Cracked teeth that have not received treatment one year after baseline do not show meaningful progression as measured by increased symptoms or number of cracks during follow-up. CLINICAL SIGNIFICANCE Untreated cracked teeth, most of which were recommended for monitoring at baseline and some of which were recommended for treatment but did not receive treatment, remained relatively stable for one year with little progression of cracks or symptoms.
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Affiliation(s)
- Thomas J Hilton
- School of Dentistry, Oregon Health &, Science University, 2730 S.W. Moody Ave, Portland, OR 97201-5042, United States.
| | - Ellen Funkhouser
- School of Medicine, University of Alabama, Birmingham, 1720 2nd Avenue South, Birmingham, AL 35294-0007, United States
| | - Jack L Ferracane
- Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University, 2730 S.W. Moody Ave, Portland, OR 97201-5042, United States
| | - Gregg H Gilbert
- Department of Clinical and Community Sciences, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Valeria V Gordan
- Department of Restorative Dental Sciences, University of Florida, 1600 SW Archer Rd, Gainesville, FL 32610, United States
| | - Sandra Bennett
- Private Practice, 22400 SE Stark Street, Gresham, OR 97030, United States
| | - Jennifer Bone
- Private Practice, 710 Hill Country Drive, Suite 1, Kerrville, TX 78028, United States
| | - Peggy A Richardson
- Private Practice, 7060 Centennial Drive, Suite 103, Tinley Park, IL 60477, United States
| | - Hans Malmstrom
- Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester, 625 Elmwood Avenue, Rochester, NY 14620, United States
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Ruben JL, Roeters FJM, Truin GJ, Loomans BAC, Huysmans MCDNJM. Cup-Shaped Tooth Wear Defects: More than Erosive Challenges? Caries Res 2019; 53:467-474. [PMID: 30840963 DOI: 10.1159/000496983] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/15/2019] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND/AIM The underlying mechanism of the development of cups and grooves on occlusal tooth surfaces is still unclear. The aim of this study was to evaluate factors contributing to in vitro cup formation, in order to elucidate the clinical process. METHODS A total of 48 extracted human molar teeth were exposed to acidic aqueous solutions at pH of 4.8 and 5.5 in constant motion, in combination with different loading conditions: no load (0N group, control), 30 N (30N group) or 50 N (50N group) (n = 8 per group). Before and after 3 months of exposure (1,422,000 loading cycles), the samples were scanned using a non-contact profilometer. Pre- and post-exposure scans were subtracted and height loss and volume tissue loss were calculated. Representative samples with wear and cupping lesions were imaged using scanning electron microscopy, light microscopy and micro-computed tomography. RESULTS Average height and volume tissue loss at pH 5.5 was 54 µm and 3.4 mm3 (0N), 52 µm and 3.4 mm3 (30N) and 58 µm and 3.7 mm3 (50N), respectively, with no statistically significant differences. Average height and volume loss at pH 4.8 were 135 µm and 8.7 mm3 (0N), 172 µm and 12.6 mm3 (30N) and 266 µm and 17.8 mm3 (50N), respectively, with a statistically significant difference between 0N and 50N (p < 0.002). Cup-shaped lesions had formed only at pH of 4.8, in the 30N and 50N groups. CONCLUSION The study showed that a cup can arise fully in enamel and that mechanical loading in addition to erosive challenges are required.
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Affiliation(s)
- Jan L Ruben
- Department of Dentistry, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands,
| | - F Joost M Roeters
- Department of Dental Materials, Academic Center for Dentistry (ACTA), Amsterdam, The Netherlands
| | - Gert-Jan Truin
- Department of Dentistry, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Bas A C Loomans
- Department of Dentistry, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
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Zhang Q, Gao S, Liu C, Lu Y, Chen X, Yu H. Evaluation of Wear Resistance of Dental Chairside CAD/CAM Glass Ceramics Reinforced by Different Crystalline Phases. JOURNAL OF TRIBOLOGY 2019. [DOI: 10.1115/1.4041536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The mechanical properties of crystalline phase of glass ceramics are critical. This study aimed to evaluate wear resistance of different crystalline-reinforced dental chairside computer-aided design/computer-aided manufacturing (CAD/CAM) glass ceramics. Materials of feldspar (Vita Mark II, VM), leucite (IPS Empress CAD, EC), lithium disilicate (IPS e.max CAD, EX), lithium disilicate enriched with zirconia (Vita Suprinity, VS), and enamel were embedded, grounded, and polished, respectively. Samples were indented with a Vickers hardness tester to test the fracture resistance (KIC). Two-body wear tests were performed in a reciprocal ball-on-flat configuration under artificial saliva. The parameters of load force (50 N), reciprocating amplitude (500 μm), frequency (2 Hz), and the test cycle (10,000 cycles) were selected. Specimen microstructure, indentation morphology, and wear scars were observed by scanning electron microscope (SEM), optical microscopy, and three-dimensional profile microscopy. EX, VS, and EC demonstrated significantly higher KIC values than the enamel, while ceramic materials showed smaller wear depth results. Cracks, massive delamination, and shallow plow were seen on the enamel worn scar. Long deep plow, delamination, and brittle cracks are more common for VM and EC, and short shallow plow and smooth subsurface are the characteristics of EX and VS. Greater fracture toughness values indicated higher wear resistances of the materials for the test glass ceramics. The CAD/CAM glass ceramics performed greater wear resistance than enamel. Feldspar- and leucite-reinforced glass ceramics illustrated better wear resistance similar to enamel than lithium disilicate glass ceramics, providing amicable matching with the opposite teeth.
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Affiliation(s)
- Qianqian Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Shanshan Gao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Chunxu Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Yuqing Lu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xin Chen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Haiyang Yu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China e-mail:
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Abstract
This article provides a brief review of recent investigations concerning the structure and properties of the tooth. The last decade has brought a greater emphasis on the durability of the tooth, an improved understanding of the fatigue and fracture behavior of the principal tissues, and their importance to tooth failures. The primary contributions to tooth durability are discussed, including the process of placing a restoration, the impact of aging, and challenges posed by the oral environment. The significance of these findings to the dental community and their importance to the pursuit of lifelong oral health are highlighted.
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Affiliation(s)
- Dwayne D Arola
- Department of Materials Science and Engineering, University of Washington School of Dentistry, Roberts Hall, 333, Box 352120, Seattle, WA 98195-2120, USA; Department of Oral Health Sciences, University of Washington School of Dentistry, Seattle, WA 98195-2120, USA; Department of Restorative Dentistry, Box 357456, University of Washington School of Dentistry, Seattle, WA 98195-7456, USA.
| | - Shanshan Gao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Renmin South Road, Chengdu, 610041, China
| | - Hai Zhang
- Department of Restorative Dentistry, Box 357456, University of Washington School of Dentistry, Seattle, WA 98195-7456, USA
| | - Radi Masri
- Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland School of Dentistry, 650 West Baltimore Street, 4th Floor, Suite 4228, Baltimore, MD 21201, USA
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Enamel Microcracks Induced by Simulated Occlusal Wear in Mature, Immature, and Deciduous Teeth. BIOMED RESEARCH INTERNATIONAL 2018; 2018:5658393. [PMID: 29850534 PMCID: PMC5926526 DOI: 10.1155/2018/5658393] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 02/12/2018] [Indexed: 11/17/2022]
Abstract
Enamel wear, which is inevitable due to the process of mastication, is a process in which the microcracking of enamel occurs due to the surface contacting very small hard particles. When these particles slide on enamel, a combined process of microcutting and microcracking in the surface and subsurface of the enamel takes place. The aim of this study was to detect microscopic differences in the microcrack behavior by subjecting enamel specimens derived from different age groups (immature open-apex premolars, mature closed-apex premolars, and deciduous molars) to cycles of simulated impact and sliding wear testing under controlled conditions. Our findings indicated that the characteristics of the microcracks, including the length, depth, count, orientation, and relation to microstructures differed among the study groups. The differences between the surface and subsurface microcrack characteristics were most notable in the enamel of deciduous molars followed by immature premolars and mature premolars whereby deciduous enamel suffered numerous, extensive, and branched microcracks. Within the limitations of this study, it was concluded that enamel surface and subsurface microcracks characteristics are dependent on the posteruptive age with deciduous enamel being the least resistant to wear based on the microcrack behavior as compared to permanent enamel.
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