Tooth structure and fracture strength of cavities

This study evaluated, in vitro, the loss of tooth substance after cavity preparation for direct and indirect restorations and its relationship with fracture strength of the prepared teeth. Sixty sound human maxillary first premolars were assigned to 6 groups (n=10). MOD direct composite cavities (Groups I, II and III) and indirect inlay cavities (Groups IV, V and VI) were prepared maintaining standardized dimensions: 2-mm deep pulpal floors, 1.5-mm wide gingival walls and 2-mm high axial walls. Buccolingual width of the occlusal box was established at 1/4 (Groups I and IV), 1/3 (Groups II and V) or 1/2 (Groups III and VI) of the intercuspal distance. Teeth were weighed (digital balance accurate to 0.001 g) before and after preparation to record tooth substance mass lost during cavity preparation. The prepared teeth were submitted to occlusal loading to determine their fracture strength using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (alpha= 0.05). 1/4-inlay cavities had higher percent mean mass loss (9.71%) than composite resin cavities with the same width (7.07%). 1/3-inlay preparations also produced higher percent mean mass loss (13.91%) than composite resin preparations with the same width (10.02%). 1/2-inlay cavities had 21.34% of mass loss versus 16.19% for the 1/2-composite resin cavities. Fracture strength means (in kgf) were: GI = 187.65; GII = 143.62; GIII = 74.10; GIV = 164.22; GV = 101.92; GVI = 50.35. Statistically significant difference (p<0.05) were observed between Groups I and IV, II and V, III and VI. Higher tooth structure loss and lower fracture strength were recorded after preparation of inlay cavities, regardless of the width of the occlusal box, compared to the direct composite resin cavities.

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Fracture Strength and Marginal Adaptation of Conservative and Extended MOD Cavities Restored with Cention N

International Journal of Dentistry ◽

10.1155/2021/5599042 ◽

2021 ◽

Vol 2021 ◽

pp. 1-7

Author(s):

Maryam Firouzmandi ◽

Ali Asghar Alavi ◽

Dana Jafarpour ◽

Soroush Sadatsharifee

Keyword(s):

Fracture Strength ◽

Resin Composite ◽

Testing Machine ◽

Marginal Adaptation ◽

Cavity Preparation ◽

Universal Testing ◽

Significant Difference ◽

Different Types ◽

Maxillary Premolars ◽

Analyze Data

The aim of the present study was to compare the fracture strength and marginal adaptation of MOD cavities restored with Cention N, bonded Cention N, and resin composite, as well as to investigate the effect of cavity preparation volume on those properties. In this experimental study, 120 human maxillary premolars were randomly divided into six groups according to the type of restoration and cavity volume (n = 20): (I) conservative MOD restored with Cention N, (II) conservative MOD restored with bonded Cention N, (III) conservative MOD restored with Z250 resin composite, (IV) extended MOD restored with Cention N, (V) extended MOD restored with bonded Cention N, and (VI) extended MOD restored with Z250 resin composite. Fracture strength (MPa) was tested using a universal testing machine. To investigate marginal adaptation, polyvinyl-siloxane impressions were taken and poured with epoxy resin. Resin replicas were examined by SEM (×400) for marginal adaptation. ANOVA tests, Tukey’s test, and independent t-test were used to analyze data ( P ≤ 0.05). Among conservative restorations, the fracture strength of bonded Cention N was significantly greater than that of Cention N ( P = 0.001), while in the extended preparations, there was no significant difference between fracture strengths of different types of restorations ( P = 0.579). In terms of marginal adaptation, there was no significant difference between different types of conservative restorations ( P = 0.232). However, in extended preparations, composite showed significantly lower marginal adaptation than Cention N and bonded Cention N ( P = 0.004 and P = 0.045, respectively). Conservative preparations showed significantly greater fracture strength and marginal adaptation compared to extended ones in groups restored with composite. The volume of cavity preparation was shown to be effective in the materials fracture strength and marginal adaptation. Cention N showed promising results in terms of fracture strength and marginal adaptation.

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Comparative Analysis of Fracture Strength of Remaining Tooth Structure after Endodontic Treatment with Various Access Cavity Preparation Techniques

The Open Dentistry Journal ◽

10.2174/1874210602014010681 ◽

2020 ◽

Vol 14 (1) ◽

pp. 681-686

Author(s):

Mohammed Mustafa ◽

Zaid A. AlJeaidi ◽

Ali Robaian AlQahtani ◽

Mohammed Ali Salem Abuelqomsan ◽

Raneem Suleiman Alofi ◽

...

Keyword(s):

Fracture Strength ◽

Fracture Resistance ◽

Statistical Tests ◽

Testing Machine ◽

Endodontic Treatment ◽

Cavity Preparation ◽

Endodontically Treated Teeth ◽

Tooth Structure ◽

Root Canals ◽

Significant Difference

Background: A perfect balance needs to be maintained between various types of endodontic access cavity preparation designs like - Traditional and conservative designed preparation to have access to the root canal system for proper cleaning and shaping of root canals without compromising the fracture resistance of the tooth structure. Aims and Objectives: We aimed to assess as well as draw comparisons of resistance against fracture of remaining tooth structure post the endodontic treatment after preparing access cavity through a variety of techniques so that we can estimate which type of cavity design technique will help endodontically treated teeth to withstand excessive load without fracture. Methods: Forty-two intact teeth (mandibular molars) were randomly selected and then were assigned to 07 different groups, inclusive of control and test groups. Various designs of access cavity preparation were done on sample teeth. The groups were divided based on different access cavity preparation designs as well as residual walls. The samples were then mounted on a composite cylinder, which was loaded under a mechanical testing machine at 0.5mm/min speed till the tooth structure fractured. This measurement of force was denoted in newton. The later analysis was carried out with the help of two-way Analysis of Variance (ANOVA) as well as Tukey’s post-hoc statistical tests. Results: There was negligible statistically relevant variance in strength towards fracture between traditional and conservative designs in teeth having three remaining walls. However, teeth with only two remaining walls fractured easily. Conclusion: Fracture resistance of teeth with remaining 03 residual walls did not show any significant difference among Traditional (TEC) and Conservative Cavity (CEC) design groups, but increased fracture strength was reported in CEC with 02 residual walls.

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Novel Microscalpels for Removing Proximal Composite Resin Overhangs on Class II Restorations

Operative Dentistry ◽

10.2341/16-012-l ◽

2017 ◽

Vol 42 (3) ◽

pp. 297-307

Author(s):

D Wolff ◽

S Schick ◽

HJ Staehle ◽

C Frese

Keyword(s):

Fracture Strength ◽

In Vitro Model ◽

Composite Resin ◽

Testing Machine ◽

Class Ii ◽

Universal Testing ◽

Composite Resin Restorations ◽

Vitro Model ◽

Post Hoc

SUMMARY Introduction: Limited access to interdental spaces complicates removal of excess material when placing class II composite resin restorations. Evidence-based recommendations on interproximal finishing are rare. We present novel microscalpels for this indication. The aim of the study was to test their fracture strength and cutting ability and to compare microscalpels with the use of a scaler, oscillating devices (G5-ProShape, G5-Proxocare), finishing strips and scalpels of sizes 12, 15, and 21 in a standardized in vitro model. Methods and Materials: Fracture strength (LOAD) and cutting forces (CUT) of microscalpels were evaluated at different angles (15, 30, 60, and 75 degrees; n=30 each) in a universal testing machine. Devices were compared in vitro using standardized composite overhangs. Marginal quality (QUAL; n=30) and quantity of excess/deficit (QUAN; n=30) were evaluated using scanning electron microscopy (SEM) for each device (explorative data analysis, Student t-test or analysis of variance; post hoc Scheffé). Results: Microscalpels showed the highest LOAD (95.8 [5.0] N) (mean [standard deviation]) and easiest cutting (CUT) (7.6 [1.5]) at 15 degrees. At all angles, LOAD was significantly higher than CUT (p<0.001). Perfect margins were seen most often with scalpel size 12 (QUAL: 37% relative frequency), while most excess (73.4%) was observed with finishing strips. QUAN was lowest with microscalpels (19.3 [4.4] μm) and highest with finishing strips (116.0 [18.8]). Use of scalers led to fractures and crack formation. Conclusion: Microscalpels are able to cut composite at a lower force than necessary to fracture the blades at all angles. Small and/or curved scalpels yield the best-quality margins.

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Influence of Different Restoration Techniques on Fracture Resistance of Root-filled Teeth: In Vitro Investigation

Operative Dentistry ◽

10.2341/17-040-l ◽

2018 ◽

Vol 43 (2) ◽

pp. 162-169 ◽

Cited By ~ 3

Author(s):

ME Hshad ◽

EE Dalkılıç ◽

GC Ozturk ◽

I Dogruer ◽

F Koray

Keyword(s):

Fracture Strength ◽

Resin Composite ◽

Testing Machine ◽

Compressive Force ◽

Control Group ◽

Hybrid Resin ◽

Flowable Composite ◽

In Vitro Investigation ◽

Significant Difference

SUMMARY Objective: The purpose of this study was to determine the fracture strength of endodontically treated mandibular premolar teeth restored with composites and different reinforcement techniques. Methods and Materials: Forty-eight freshly extracted human mandibular premolar teeth were randomly divided into four groups: group IN, group CR, group FRC, and group PRF. Group IN consisted of teeth with intact crowns and served as the control group. In the other three groups, endodontic treatment was performed and standard mesio-occluso-distal (MOD) cavities were prepared. Then cavities were restored with hybrid resin composite only, flowable composite and hybrid resin composite, and Ribbond, flowable composite and hybrid resin composite in groups CR, FRC and PRF, respectively. All of the teeth were subjected to fracture by means of a universal testing machine, and compressive force was applied with a modified stainless-steel ball at a crosshead speed at 0.5 mm/min. Results: The highest values were observed in group IN, while the lowest values were determined in group CR. There was not any statistically significant difference between group CR and group FCR (p>0.05). When groups CR, FCR, and PRF were compared, group PRF showed significantly better fracture strength than did groups CR and FCR (p<0.05). It was determined that there was not any significant difference between group IN and group PRF (p>0.05). Conclusions: Polyethylene ribbon fiber considerably increases the fracture strength of mandibular premolar teeth with MOD cavities restored with composite.

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The effect of caries detector dyes and a cavity cleansing agent on composite resin bonding to enamel and dentin

Journal of Clinical Pediatric Dentistry ◽

10.17796/jcpd.25.1.781012816642v3t5 ◽

2001 ◽

Vol 25 (1) ◽

pp. 57-63 ◽

Cited By ~ 14

Author(s):

Azza El-Housseiny ◽

Hana Jamjoum

Keyword(s):

Bond Strength ◽

Shear Bond Strength ◽

Composite Resin ◽

Testing Machine ◽

Group Iv ◽

Acid Etching ◽

Group V ◽

Universal Testing ◽

Group I ◽

Significant Difference

This study was undertaken to evaluate the effect of caries detector dyes and/or cavity cleanser on composite bonding and etching patterns of enamel and dentin. One hundred and eight non-carious premolars were divided into six groups according to the enamel and dentin pretreatment investigated. The different pretreatment were as follows: Group I: teeth with prophylaxis only, Group II: Sable seek caries detector dye,Groups III: chlorhexidine cavity cleanser,Group IV: the caries detectors dye followed by prophylaxis, Group V: the cavity cleanser followed by the caries detector dye, and Group IV: Snoop caries detector dye. The shear bond strength of composite resin bonded to enamel and dentin was evaluated by the Instron Universal testing machine while, the topographic details of enamel and dentin were examined by the SEM following the different pretreatment and acid etching. Results of the shear bond strength showed no statistically significant difference among the six groups, with no substantial differences in SEM results. It is concluded that using the caries detector dyes and/or chlorhexidine cavity cleanser before acid etching does not significantly affect composite bonding to enamel and dentin.

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Influence of adhesive system and bevel preparation on fracture strength of teeth restored with composite resin

Brazilian Dental Journal ◽

10.1590/s0103-64402010000400007 ◽

2010 ◽

Vol 21 (4) ◽

pp. 327-331 ◽

Cited By ~ 14

Author(s):

Fábio Herrmann Coelho-de-Souza ◽

Analice da Cunha Rocha ◽

Alessandro Rubini ◽

Celso Afonso Klein-Júnior ◽

Flávio Fernando Demarco

Keyword(s):

Fracture Strength ◽

Composite Resin ◽

Testing Machine ◽

Adhesive System ◽

Butt Joint ◽

Fracture Pattern ◽

Single Bond ◽

Adhesive Systems ◽

Exact Test ◽

Universal Testing

The aim of this study was to evaluate the fracture strength of teeth with different cavosurface margin cavity preparations and restored with composite resin and different adhesive systems. Eighty premolars were randomly divided in 8 groups, as follow: G1- sound teeth; G2- MOD preparation (no restoration); G3- Adper Single Bond without bevel preparation (butt joint); G4- Adper Single Bond with bevel preparation; G5- Adper Single Bond with chamfer preparation; G6- Clearfil SE Bond without bevel (butt joint); G7- Clearfil SE Bond with bevel preparation; G8- Clearfil SE Bond with chamfer preparation. The adhesive systems were applied according to manufacturers’ instructions. Composite resin (Filtek Z250) was incrementally placed in all cavities. After 24 h, the specimens were tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey’s test (fracture strength) and Fisher’s exact test (fracture pattern). The confidence level was set at 95% for all tests. Prepared and non-restored teeth showed the worst performance and G4 exhibited the highest fracture strength among all groups (p<0.05). In conclusion, all restorative treatments were able to recover the fracture strength of non-restored teeth to levels similar to those of sound teeth. Using a total-etch adhesive system with bevel preparation significantly improved the resistance to fracture.

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Comparison of Fracture Strengths among different Commonly Placed Anterior Esthetic Restorations for Primary Dentition: An in vitro study

Journal of Clinical Pediatric Dentistry ◽

10.17796/1053-4625-45.3.5 ◽

2021 ◽

Vol 45 (3) ◽

pp. 171-176

Author(s):

Brent Lin ◽

Amit Khatri ◽

Michael Hong

Keyword(s):

Fracture Strength ◽

Testing Machine ◽

In Vitro Study ◽

Vitro Study ◽

Anterior Teeth ◽

Study Results ◽

Luting Cement ◽

Significant Difference ◽

All Ceramic

The purpose of this study was to determine and compare the shear force (N) required to fracture or dislodge an all-ceramic zirconia-based crown using different luting cement with those of polycarbonate crown and strip crown for the primary anterior teeth in vitro. Study design: Four groups of esthetic restoration for primary anterior teeth were tested for fracture strength: 1) Fifteen all-ceramic zirconia-based crowns cemented with glass ionomer cement, 2) Fifteen all-ceramic zirconia-based crowns bonded with a self-adhesive resin cement, 3) Fifteen polycarbonate crowns cemented with a polymer reinforced zinc-oxide eugenol and 4) Fifteen resin strip crowns. All restorations were placed and cemented on reproductions of dies in an independent laboratory at Delhi, India. All samples underwent loading until fracture or dislodgement with the Universal Testing Machine. The force in Newton (N) required to produce failure was recorded for each sample and the type of failures was also noted and characterized. One-way analysis of variance (ANOVA) test and the Tukey and Scheffe’s post hoc comparisons were used for statistical analyses. Results: In this invitro study, results were measured in Newtons (N). Group 1 (410.9±79.5 N) and Group 2 (420.5±57.8 N) had higher fracture strength than Group 3 (330.3±85.6 N) and Group 4 (268.4±28.2 N). These differences were statistically significant at P≤.05 among the sample groups. No significant difference was found between groups 1 and 2 (P = 0.984) nor between groups 3 and 4 (P =0.104). Among type of failures, majority of restoration fractures for zirconia-based crowns and resin strip crowns were due to cohesive failures and polycarbonate crowns had predominantly mixed failures. Conclusions: Under the limitations of this in vitro study, it could be concluded that all-ceramic zirconia-based crowns attained the highest fracture strength among all restorative samples tested regardless of the type of luting agent employed (P<.01). Cohesive failures were commonly observed in the zirconia crowns and resin strip crowns, whereas polycarbonate crowns revealed predominately mixed failures.

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Effects of Carbonated Drinks on Mechanical Properties of Three Types of Thermoplastic Aligner Materials: An In vitro Study

The Journal of Indian Orthodontic Society ◽

10.1177/0301574219892421 ◽

2020 ◽

Vol 54 (2) ◽

pp. 115-120

Author(s):

Leyona Pushpa Femina I. ◽

Chandrashekar B.S. ◽

Arun A.V ◽

Aravind S. Raju ◽

Ramesh Kumar P.C. ◽

...

Keyword(s):

Mechanical Properties ◽

Artificial Saliva ◽

Testing Machine ◽

In Vitro Study ◽

Control Groups ◽

Universal Testing ◽

In Vitro Aging ◽

Before And After ◽

Carbonated Drinks

Objectives: The aim was to assess the mechanical properties of the three types of thermoplastic aligner materials before and after in vitro aging with carbonated drinks. Materials and methods: Twelve samples of thermoplastic aligner materials produced by three different manufacturers (Leone S.P.A, Florence, Italy; Duran, SCHEU-dental GmbH, Iserlohn, Germany; Essix ACE, Dentsply Raintree Essix, United States) were selected. Samples were thermoformed and later aged in vitro at a constant temperature in artificial saliva along with carbonated drinks (10 min each day) for 2 weeks. The mechanical properties were characterized using universal testing machine such as instron (MultiTest 10-i) and the results were compared with the control groups (before exposure to carbonated drinks). Results: All the above-mentioned thermoplastic materials tested showed an insignificant ( p > 0.05) decrease in stiffness, yield strength, and elastic modulus after aging. The stiffness of the thermoplastic materials increased with an increase in thickness. The flexure modulus was higher for the thinner materials, whereas it was lower for the thicker materials. Conclusion: Experimental results indicate that the aligner material will remain stable during and following exposure to carbonated drinks, which suggests that the orthodontic force from thermoplastic appliances does not decrease with clinical usage of carbonated drinks.

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Can Fiber Application Affect the Fracture Strength of Endodontically Treated Teeth Restored with a Low Viscosity Bulk-Fill Composite?

BioMed Research International ◽

10.1155/2019/3126931 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Evrim Eliguzeloglu Dalkılıç ◽

Magrur Kazak ◽

Duygu Hisarbeyli ◽

Mehmet Ali Fildisi ◽

Nazmiye Donmez ◽

...

Keyword(s):

Fracture Strength ◽

Fracture Resistance ◽

Testing Machine ◽

The Other ◽

Control Groups ◽

Endodontically Treated Teeth ◽

Low Viscosity ◽

Universal Testing ◽

Significant Difference ◽

Insertion Techniques

Objective. The aim of this study is to evaluate the effects of different fiber insertion techniques and thermomechanical aging on the fracture resistance of endodontically treated mandibular premolar teeth restored using bulk-fill composites. Materials and Methods. Eighty human mandibular premolar teeth were randomly divided into eight groups: Group IN, Group BF, Group PRF1, Group PRF2, Group IN-TMA, Group BF-TMA, Group PRF1-TMA ,and Group PRF2-TMA. Group IN (intact) and Group IN-TMA (intact but subjected to thermomechanical aging) served as control groups. In the other six groups, endodontic treatment was performed and standardized mesio-occluso-distal (MOD) cavities were prepared. In BF, PRF1, and PRF2, the cavities were restored with bulk-fill composite only, bulk-fill/Ribbond, and bulk-fill/additional Ribbond, respectively. In BF-TMA, PRF1-TMA, and PRF2-TMA, the teeth were subjected to thermomechanical aging after the restorations. All of the teeth were fractured on the universal testing machine. Fracture surfaces were analyzed with a stereomicroscope. Results. Control groups showed significantly higher fracture strengths than tested groups (P<0.05). No statistically significant difference was observed among the tested groups (P>0.05). Most of the favorable fractures were seen in PRF1, PRF2, and PRF2-TMA. Most of the unfavorable fractures were seen in BF-TMA. Conclusions. Although fiber insertion with different techniques did not increase the fracture strength of teeth restored with bulk-fill composites, it increased the favorable fracture modes. Thermomechanical aging did not change the fracture strength of the groups.

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Fracture Strength of Ceramic Bracket Tie Wings Subjected to Force Direction

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.330-332.1353 ◽

2007 ◽

Vol 330-332 ◽

pp. 1353-1356

Author(s):

Kyoung Nam Kim ◽

Sang Bae Lee ◽

H.J. Kim ◽

J.S. Choi ◽

Kwang Mahn Kim ◽

...

Keyword(s):

Fracture Strength ◽

Testing Machine ◽

Compressive Force ◽

Test Device ◽

Steel Cylinder ◽

Paired Samples ◽

Universal Testing ◽

Significant Difference ◽

Force Direction ◽

Ceramic Bracket

In this study, the effects of bracket designs and force direction on fracture strength of alumina bracket were evaluated. Two differently designed alumina brackets (MISO, HT Co., Ltd., Seoul, Korea) were tested. Each bracket was bonded with orthodontic adhesive to stainless steel cylinder. Compressive force was applied to the tie wing of bracket at 30°, 60°, and 90° to the long axis of the test device. Fracture strengths were assessed by using a universal testing machine (Instron 3366, Instron Co., Ltd., U.S.A.). Fractured bracket surfaces were examined using SEM. Statistical analysis was performed by using SPSS 9.0 for Windows program. Paired samples t-tests and Kruskal-wallis tests were used at P<0.05. The fracture strength ranged from 150 N with the occlusal wing to 63 N with the cervical wing in bracket A. A significant difference was founded in fracture strength between the bracket designs and force directions. Based on this result, it could be concluded that bracket designs and force direction was important rule to improve fracture strength of ceramic bracket.

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