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Weimann D, Fleck C, Razi H. Marginal integrity in minimally invasive molar resin composite restorations: Impact of polymerization shrinkage. J Mech Behav Biomed Mater 2024; 155:106554. [PMID: 38676971 DOI: 10.1016/j.jmbbm.2024.106554] [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: 01/29/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/29/2024]
Abstract
OBJECTIVES This study utilized non-linear finite element (FE) models to explore polymerization shrinkage and its impact on marginal integrity in molars following both selective caries removal (SCR) and conventional treatment. Specifically, we performed 2D in silico simulations to study residual stresses post-resin polymerization shrinkage and their influence on the marginal integrity of various restoration types. METHODS Initially, FE models were developed based on a cohesive zone framework to simulate crack propagation along the bonded interfaces between restoration and tooth structure in SCR-treated molars with class I and class II restorations. The modeled resin composite restorations first underwent polymerization shrinkage and were then subjected to various occlusal loading conditions. Stress magnitudes and distributions were identified to evaluate the margin integrity and predict the mechanism and location of interfacial failure. RESULTS AND DISCUSSION The FE models computed polymerization shrinkage stresses of less than 1 MPa, exerting a minor influence on the composite/tooth interface. Occlusal loading, however, significantly impacted the load-bearing capacity of the composite/tooth (c/t) interface, potentially jeopardizing the restoration integrity. Especially under bi-axial occlusal loading, interfacial debonding occurred in the vertical cavity walls of the class I restorations, increasing the risk of failure. Notably, SCR-treated teeth exhibited better margin integrity than restored teeth after complete caries removal (NCR). These findings provide valuable insights into the mechanical behavior of SCR-treated teeth under different loading conditions and highlight the importance of considering the load scenarios that may lead to failure at the c/t interface. By investigating the factors influencing crack initiation and delamination, this novel research contributes to the optimization of restorative treatments and aids in the design of more resilient dental restorations.
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Affiliation(s)
- Dominique Weimann
- Materials Science and Engineering, Technische Universität Berlin, Berlin, Germany
| | - Claudia Fleck
- Materials Science and Engineering, Technische Universität Berlin, Berlin, Germany.
| | - Hajar Razi
- ETH Zurich, Zurich, Switzerland; WoodTec Group, Cellulose & Wood Materials Laboratory, Empa, Dübendorf, Switzerland.
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Sadr A, Bakhtiari B, Hayashi J, Luong MN, Chen YW, Chyz G, Chan D, Tagami J. Effects of fiber reinforcement on adaptation and bond strength of a bulk-fill composite in deep preparations. Dent Mater 2020; 36:527-534. [PMID: 32044045 DOI: 10.1016/j.dental.2020.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 11/23/2019] [Accepted: 01/14/2020] [Indexed: 10/25/2022]
Abstract
OBJECTIVE This study investigated the effect of plasma-treated leno weaved ultra-high-molecular-weight polyethylene fiber placement on gap formation and microtensile bond strength (MTBS) of a bulk-fill composite in deep cavity. METHODS Resin composite molds (3 mm width, 4 mm depth) were treated with Clearfil SE Bond 2 and restored with 3 techniques : (1) Surefil SDR flow (SDR) placed in bulk (BLK), (2) SDR placed in two unequal increments (INC) and (3) SDR placed after an increment of SDR placed with wetted polyethylene fiber (Ribbond Ultra) at the cavity floor (FRC). As a control, the cavities were bulk-filled with SDR and no bonding agent (n = 12). All the specimens were subjected to real-time and 3D imaging by SS-OCT (1330 nm) to calculate the total volume of gap formed (mm3) at the cavity floor and between the composite increments. For MTBS, the occlusal cavities of the similar dimensions (3 × 3 × 4 mm3) were prepared on extracted molars with similar composite placement techniques (BLK, INC and FRC). After 24 h 37 °C water storage, the specimens were sectioned using a diamond saw to create 0.7 × 0.7 mm2 beams for MTBS, and subjected to bond testing at a crosshead speed of 1 mm/min. Data for both tests was analyzed by one-way ANOVA and multiple-comparisons with Bonferroni correction (α = 0.05). RESULTS The gap volumes were different among the groups (p < 0.05). The largest cavity floor gaps (mm3) were observed in the control group (2.00 ± 0.08); followed by BLK (0.74 ± 0.20) and INC (0.02 ± 0.01). In FRC, the cavity floor was gap-free in all specimens but some separation was observed between the two increments. MTBS values (MPa) were 13.8 ± 7.6, 31.7 ± 12.5 and 28.3 ± 8.5 for BLK, INC and FRC groups. There was no significant difference between FRC and INC and both were different from BLK (p < 0.05). SIGNIFICANCE Gap formation of the bulk-fill composite at cavity floor was significantly reduced with the placement of a fiber-reinforced increment at the base of the deep preparation. The fiber-reinforced increment acts as a shrinkage stress breaker and protects the bonded interface at deep dentin.
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Affiliation(s)
- Alireza Sadr
- Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, Department of Restorative Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA; Cariology and Operative Dentistry Department, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
| | - Behnoush Bakhtiari
- Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, Department of Restorative Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA; School of Dentistry, University of Michigan, 1011 N University Ave, Ann Arbor, MI 48109, USA
| | - Juri Hayashi
- Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, Department of Restorative Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA; Cariology and Operative Dentistry Department, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
| | - Minh N Luong
- Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, Department of Restorative Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA
| | - Yen-Wei Chen
- Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, Department of Restorative Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA
| | - Grant Chyz
- Private Practice, 509 Olive Way # 1142, Seattle, WA 98101, USA
| | - Daniel Chan
- Biomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, Department of Restorative Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA
| | - Junji Tagami
- Cariology and Operative Dentistry Department, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
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Enochs T, Hill AE, Worley CE, Veríssimo C, Tantbirojn D, Versluis A. Cuspal flexure of composite-restored typodont teeth and correlation with polymerization shrinkage values. Dent Mater 2017; 34:152-160. [PMID: 29061285 DOI: 10.1016/j.dental.2017.09.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/04/2017] [Accepted: 09/26/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVE The relationship between post-gel shrinkage, total shrinkage, and cuspal flexure was examined. Cuspal flexure was measured on restored typodont teeth, which offered a standardized tooth shape for comparison of shrinkage stress effects among restorative composites. METHODS Six restorative composites were compared (Filtek LS, Venus Flowable, Tetric EvoCeram, Filtek Flowable, Esthet-X, and Filtek Supreme). Total shrinkage was determined from changes in projected surface area before and after polymerization (n=10). Post-gel shrinkage was determined with a biaxial strain gauge that measured strain development during polymerization (n=10). Cuspal flexure was determined using typodont maxillary second premolars with standard MOD slot preparation (n=10). Flexure was determined by comparing the three-dimensionally scanned cuspal surfaces before and after restoration. Restoration bonding to the typodont cavity was achieved by sandblasting and adhesive application. Bond integrity was verified by measuring dye penetration. Results were analyzed using ANOVA and Student-Newman-Keuls post hoc test (significance level 0.05). Pearson was used for correlations. RESULTS Total and post-gel shrinkage were significant different for all composites (t-test; P<0.001). Depending on the composite, only 9-41% of the total shrinkage was recorded as post-gel shrinkage. Bond integrity of restored typodont teeth was 96-99%. Cuspal flexure correlated strongly with post-gel shrinkage, but there was no correlation with total shrinkage. SIGNIFICANCE Cuspal flexure of restored typodont teeth showed the effect of shrinkage stress caused by polymerizing composite restorations, ensuring standardization while maintaining the effects of tooth/cavity geometry. Post-gel shrinkage gave a good indication to screen composites for the stress they may generate; total shrinkage had no direct correlation with stress.
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Affiliation(s)
- Taylor Enochs
- College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA.
| | - Anne E Hill
- Department of Restorative Dentistry, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA.
| | | | - Crisnicaw Veríssimo
- Department of Restorative Dentistry, University of Uberaba, Uberaba, MG, Brazil.
| | - Daranee Tantbirojn
- Department of Restorative Dentistry, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA.
| | - Antheunis Versluis
- Department of Bioscience Research, College of Dentistry, University of Tennessee Health Science Center, 875 Union Ave, Memphis, TN 38163, USA.
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Prejzek O, Španiel M, Mareš T. Microstructural residual stress in particle-filled dental composite. Comput Methods Biomech Biomed Engin 2015; 18:124-9. [DOI: 10.1080/10255842.2013.781158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Rees JS, Jagger DC, Williams DR, Brown G, Duguid W. A reappraisal of the incremental packing technique for light cured composite resins. J Oral Rehabil 2004; 31:81-4. [PMID: 15125602 DOI: 10.1046/j.0305-182x.2003.01073.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cuspal flexure caused by a direct placement composite resin was measured using a technique that did not interfere with cuspal movement. Twenty upper premolar teeth with mesial-occlusal-distal (MOD) cavity preparations were restored using a posterior composite resin. Ten teeth were restored using a bulk packing technique and 10 were restored using three 'U' shaped bucco-lingual increments. Total cuspal movement was measured 1 h following the initiation of curing. Bulk placement of the composite resin produced slightly more cuspal movement (12.5 microm) compared with the incremental placement of composite (11.3 microm). This difference was not statistically significant. The technique of incremental packing to reduce cuspal flexure is therefore questioned.
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Affiliation(s)
- J S Rees
- Division of Restorative Dentistry, University of Bristol Dental School, Bristol, UK.
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Laughlin GA, Williams JL, Eick JD. The influence of system compliance and sample geometry on composite polymerization shrinkage stress. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2003; 63:671-8. [PMID: 12209915 DOI: 10.1002/jbm.10386] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The objective of this study was to use finite-element analysis to model tensilometer tests of polymerizing dental composites. A typical sample in polymerization shrinkage stress tests is shaped like a flat disk, that is, has a high aspect ratio (ratio of diameter to height). In the experimental literature it is implied that the induced stress state in the flat disk composite samples is uniaxial. Three published tensilometer tests of curing dental composite samples with similar high aspect ratios (varying from 3 to 5) were modeled, but with test configurations having low, intermediate and high relative compliance (a tenfold variation). With the use of linear elastic finite element analysis, an instantaneous volumetric shrinkage of 1% was applied to the composite via the thermal analogy and the following questions were addressed: 1. Does the numerically predicted state of stress in composite samples tested in this fashion differ substantially from the uniaxial stress state assumed in the experiments?2. How do the numerically predicted stresses compare with the experimentally determined nominal stresses?3. Does compliance of the mountings influence the numerically predicted stress state? The finite-element results predicted a complex triaxial stress state that was strongly influenced by the compliance of the mountings. For the low and intermediate system compliance the model overpredicted the polymerization contraction stress, as would be anticipated due to the inability of the model to account for viscoplastic flow. For high system compliance, the numerical and experimental stress values were in better agreement, mainly because the linear elastic mountings accounted for most of the measured system compliance.
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Affiliation(s)
- Gayle A Laughlin
- Department of Oral Biology, School of Dentistry, University of Missouri at Kansas City, 64108, USA.
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Hubsch P, Middleton J, Knox J. The influence of cavity shape on the stresses in composite dental restorations: a finite element study. Comput Methods Biomech Biomed Engin 2002; 5:343-9. [PMID: 12745431 DOI: 10.1080/1025584021000016861] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Dental restoration adhering to the cavity exhibits fundamentally different load transfer mechanisms from non-adhering restorations. It is therefore questionable that traditional cavity designs are optimal from a purely mechanical point of view when working with composite materials. Drawing from general engineering experience, it can be hypothesised that smooth, well rounded designs with bevelled margins are superior. A finite element model is used in the present investigation to determine the stress field in four different cavity designs as it develops during the curing of the restoration. The results show that a significant reduction of the stress along the adhesive interface between the tooth and the restoration can be achieved through the use of a rounded cavity shape. They also show that the adoption of bevelled margins leads to a reduction of the stress concentration at this location. These results are confirmed by a set of experimental results published in the literature. It is concluded that adhering restorations will perform better from a mechanical point of view if an appropriate cavity shape is selected.
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Affiliation(s)
- Pierre Hubsch
- Biomechanics Research Unit, Dental Health and Biological Sciences, University of Wales College of Medicine, Cardiff Medicentre, Heath Park, Cardiff CF14 4UJ, Wales, UK
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Ensaff H, O'Doherty DM, Jacobsen PH. The influence of the restoration-tooth interface in light cured composite restorations: a finite element analysis. Biomaterials 2001; 22:3097-103. [PMID: 11603580 DOI: 10.1016/s0142-9612(01)00058-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This study examines the early shrinkage behaviour of dental composite resins, and in particular the interfacial stresses around the margins of a composite restoration. The development of stresses at the restoration-tooth interface can have a detrimental effect on the longevity of a restoration. The influence of this interface on the stress system generated in the tooth was examined using finite element analysis. The restoration-tooth interface was simulated using spring elements of varying spring constants (k = 1, 10(2), 10(4), 10(10) N/mm). Interfacial stresses varied from -0.15 to 0.42 MPa for a spring constant of 1 N/mm, and from -19 to 68 MPa for a spring constant of 10(10) N/mm. Correlations between stiffness at the restoration-tooth interface and higher shrinkage stresses due to restricted shrinkage were found. Interfacial failure at the upper and lower regions of the interface, as well as cuspal movements of the order of 2 microm were predicated for the model of the highest spring constant, 10(10) N/mm. The restoration-tooth interface modelled by the spring elements was seen to have a conclusive effect on the ensuing stress system, as well as the longevity of the restoration.
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Affiliation(s)
- H Ensaff
- Department of Mechanical and Medical Engineering, University of Bradford, West Yorkshire, UK.
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9
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Knox J, Kralj B, Hübsch PF, Middleton J, Jones ML. An evaluation of the influence of orthodontic adhesive on the stresses generated in a bonded bracket finite element model. Am J Orthod Dentofacial Orthop 2001; 119:43-53. [PMID: 11174539 DOI: 10.1067/mod.2001.110987] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to evaluate the stresses generated in the bracket-cement-tooth continuum by a tensile load case when the physical and geometric properties of cement are varied. A 2-stage approach was used. In the first stage, a validated 3-dimensional finite element model of the bracket-cement-tooth system was constructed that consisted of 15,324 nodes and 2971 finite elements. Bracket base geometry was held constant; the physical properties (elastic modulus; Poisson's ratio) and geometry (lute thickness) of the cement varied. A simplified 2-dimensional model was then developed to investigate the localized effects of the cement lute thickness and the shape of the lute periphery on the stress distribution in the system. Small increases in stress were recorded under load within the cement as the rigidity of the cement increased. Similarly, Poisson's ratio values above 0.4 appeared to have a small influence on the major principal stresses in the impregnated wire mesh layer when a tensile force was applied. Variation in lute thickness was shown to have an influence on the distribution of major principal stresses within the cement lute. Increased stresses were recorded at the lute periphery as the lute dimensions increased. The morphologic features of the lute periphery also appeared to have had a significant effect on the performance of an orthodontic adhesive. Acute cement-enamel angles resulted in an increased chance of singularity development and attachment failure. The physical properties and thickness of the cement lute and the shape of the cement lute periphery contribute to the stress distribution within the bracket-cement-tooth continuum and, therefore, the quality of orthodontic attachment provided.
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Affiliation(s)
- J Knox
- Department of Dental Health and Development, University of Wales College of Medicine, Dental School, Cardiff, UK.
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10
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Winkler MM, Chen J, Qian H, Hamula DW, Carlson TJ, Katona TR. Experimental validation of a finite element model of light-activated polymerization shrinkage. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2000; 53:554-9. [PMID: 10984704 DOI: 10.1002/1097-4636(200009)53:5<554::aid-jbm15>3.0.co;2-l] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An important consideration in improving the longevity of dental resin composite restorations is how to minimize the stresses that develop between resin composites and the wall of the preparation as the resin shrinks during polymerization. If the stress is too great, failure of the bonded interface occurs and microleakage results, with possible margin failure, staining, and secondary caries. This present project was performed to validate a previously developed FEM approach for investigating polymerization shrinkage. Light-cured resin composite was condensed into a cylindrical cavity preparation, which contained a centrally located wire. A profilometer stylus was positioned on the end of the wire to detect the initial surface displacement as the wire moved with the superficial layer of composite resin. The plots of the experimentally derived data were compared to the data plot from the FEM. The initial segments of the experimental plots matched the calculated plot very closely in shape, thus validating the FEM approach.
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Affiliation(s)
- M M Winkler
- Department of Operative Dentistry and Biomaterials, LSU School of Dentistry, 1100 Florida Ave., New Orleans, Louisiana 70119, USA.
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Dauvillier BS, Feilzer AJ, De Gee AJ, Davidson CL. Visco-elastic parameters of dental restorative materials during setting. J Dent Res 2000; 79:818-23. [PMID: 10765954 DOI: 10.1177/00220345000790030601] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Contraction stresses generated in restoratives during setting are among the major problems in adhesive dentistry, since they often result in loss of adhesion from the cavity walls or in post-operative pain. The rate of stress development and the ultimate magnitude of the stress, which determine the seriousness of these problems, depend on the relatively unknown visco-elastic behavior of the restoratives during setting. The aim of this study was to determine the visco-elastic parameters during setting, to aid our understanding of the process of contraction stress development. A dynamic mechanical method was used in which the materials were subjected to periodic strain cycles in a universal testing machine during the first 60 min of setting. The visco-elastic parameters (viscosity eta and Young's modulus E) were calculated by analysis of the experimental stress-strain data with a simple mechanical model according to Maxwell. Two restorative materials from different classes were investigated: a two-paste resin composite and a conventional glass-ionomer cement. A comparison of the results showed significant differences in the development of viscosity and stiffness in the early stage of setting. The resultant relaxation time (eta/E) of the glass ionomer remained at a low level during the first 15 min, whereas that of the resin composite increased markedly. This is of clinical importance, since it implies that, during the early setting stage, glass ionomers are better capable of reducing the contraction stresses than resin composites, thus increasing the likelihood that the bond with the cavity walls will form and survive during setting.
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Affiliation(s)
- B S Dauvillier
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands.
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12
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Korioth TW, Versluis A. Modeling the mechanical behavior of the jaws and their related structures by finite element (FE) analysis. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1997; 8:90-104. [PMID: 9063627 DOI: 10.1177/10454411970080010501] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In this paper, we provide a review of mechanical finite element analyses applied to the maxillary and/or mandibular bone with their associated natural and restored structures. It includes a description of the principles and the relevant variables involved, and their critical application to published finite element models ranging from three-dimensional reconstructions of the jaws to detailed investigations on the behavior of natural and restored teeth, as well as basic materials science. The survey revealed that many outstanding FE approaches related to natural and restored dental structures had already been done 10-20 years ago. Several three-dimensional mandibular models are currently available, but a more realistic correlation with physiological chewing and biting tasks is needed. Many FE models lack experimentally derived material properties, sensitivity analyses, or validation attempts, and yield too much significance to their predictive, quantitative outcome. A combination of direct validation and, most importantly, the complete assessment of methodical changes in all relevant variables involved in the modeled system probably indicates a good FE modeling approach. A numerical method for addressing mechanical problems is a powerful contemporary research tool. FE analyses can provide precise insight into the complex mechanical behavior of natural and restored craniofacial structures affected by three-dimensional stress fields which are still very difficult to assess otherwise.
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Affiliation(s)
- T W Korioth
- Department of Oral Science, Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB), School of Dentistry, University of Minnesota, Minneopolis, Minnesota 55455, USA
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13
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Katona TR, Winkler MM, Huang J. Stress analysis of a bulk-filled Class-V chemical-cured dental composite restoration. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1996; 31:445-9. [PMID: 8836839 DOI: 10.1002/(sici)1097-4636(199608)31:4<445::aid-jbm2>3.0.co;2-l] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Clinical problems associated with the polymerization shrinkage of dental composite restorations include tooth sensitivity, crown fracture, discoloration, recurrent decay, and loss of restoration. Our goal was to determine whether these complications could be attributed to the transient stresses developed during contraction. Thus, a finite element model was used to calculate the transitory deformations and composite-tooth interface stresses produced during the shrinkage of a chemical-cured ideal Class-V composite restoration. It was found that the interface stress peaks moved with the polymerization front, and that in some instances, their intermediate magnitudes were higher than the final, fully cured, values. Therefore, the results indicate that clinical failure may be related to these transitory changes during the polymerization process.
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Affiliation(s)
- T R Katona
- Orthodontics Division, Indiana University-Purdue University at Indianapolis, USA
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14
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Winkler MM, Katona TR, Paydar NH. Finite element stress analysis of three filling techniques for class V light-cured composite restorations. J Dent Res 1996; 75:1477-83. [PMID: 8876599 DOI: 10.1177/00220345960750070701] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
An important disadvantage of current dental resin composites is polymerization shrinkage. This shrinkage has clinical repercussions such as sensitivity, marginal discoloration, and secondary caries. The objective of this study was to compare three filling techniques in terms of the transient stresses induced at the resin composite/tooth interface during polymerization. The techniques were: bulk filling (B), three horizontal increments (HI), and three wedge increments (WI). A simple Class V cavity preparation was modeled in finite element analysis. Polymerization shrinkage was simulated by a thermal stress analogy, thereby causing 1% shrinkage due to an arbitrary coefficient of thermal expansion. Interface normal and shear stresses were calculated at nine steps during polymerization, proceeding from 0% to 100% volume of cured resin. The importance of the interface transient stresses was revealed by the finding that, in most cases, their peak values exceeded the final or residual stress. Also, the WI and B techniques consistently exhibited the highest and lowest maximum transient stresses, respectively. These results from the simple model of a Class V restoration suggest that bulk filling of light-cured resin composites should be used in restorations which are sufficiently shallow to be cured to their full depth.
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Affiliation(s)
- M M Winkler
- Dental Materials Division, Indiana University-Purdue University at Indianapolis, School of Dentistry 46202, USA
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15
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Katona TR, Winkler MM. Stress analysis of a bulk-filled Class V light-cured composite restoration. J Dent Res 1994; 73:1470-7. [PMID: 8083445 DOI: 10.1177/00220345940730081201] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Clinical failures are often associated with the polymerization shrinkage of resin composite restorative materials. These problems include tooth sensitivity and fracture, marginal leakage, loss of the restoration, and recurrent decay. Our goal was to examine transient composite distortions and interface stresses as a bulk-filled light-cured composite polymerized in a Class V restoration. The analysis was based on a finite element model. The curing of the restoration was divided into 4 steps: approximately 1/30, 1/4, 1/2, and full depth (1/1) of cure. Since the actual curing pattern is not known, calculations were performed for three hypothetical (flat, convex, and concave) polymerization front shapes. The calculations showed that the assumed shape was a critical factor in determining cured surface deformations. For example, the initial cure depth (1/30) resulted in a surface bulge if the polymerization front was presumed convex, while the concave front resulted in a large intrusion. By the time that about 1/2 the depth of the restoration was cured, the differences were essentially gone. The final surface outline was intruded. Interface stresses in the curing restoration were qualitatively similar regardless of the assumed polymerization shape. As with surface distortions, the stresses changed with curing depth. It was concluded that (1) transient events during polymerization are possible contributors to clinical complications, and (2) more must be known about the polymerization pattern.
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Affiliation(s)
- T R Katona
- Orthodontics Division, School of Dentistry, Indiana University-Purdue University, Indianapolis 46202
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Hübsch PF, Middleton J, Rees JS, Jacobsen PH. An adaptive finite-element approach for the analysis of dental restorations. JOURNAL OF BIOMEDICAL ENGINEERING 1993; 15:401-8. [PMID: 8231157 DOI: 10.1016/0141-5425(93)90077-c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The present paper deals with the problem of stresses generated during the setting process of polymer tooth fillings. A finite element procedure capable of accurately predicting the stresses along an interface between two different materials is presented. Adaptation of the finite element mesh is carried out based on a simple error estimator. The procedure is tested against benchmark problems and then applied to polymer tooth fillings. The results of the study are relevant in understanding and improving the behaviour of dental restorations.
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Affiliation(s)
- P F Hübsch
- Department of Civil Engineering, University College of Swansea, UK
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