The Journal of Contemporary Dental Practice

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2008 | February | Volume 9 | Issue 2

RESEARCH ARTICLE

Mohamed F. Ayad

Effect of the Crown Preparation Margin and Die Type on the Marginal Accuracy of Fiber-reinforced Composite Crowns

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:9 - 16]

PDF  |  DOI: 10.5005/jcdp-9-2-9  |  Open Access |  How to cite  | 

Abstract

Aim

The objective of this laboratory investigation was to determine the effect of different preparation designs (light chamfer, deep chamfer, and shoulder) and die-making materials (stone and epoxy) on the resulting margin misfit for fiber-reinforced composite crowns using a measuring microscope.

Methods and Materials

Sixty standardized FibreKor crowns were made on stone and epoxy resin dies (n=30 each) duplicated from three metal master dies representing complete crown tooth preparation with a total convergence of 5°. For each die group, three of the tooth preparation designs were established in relation to the type of finish line (n=0 each) as follows: Group A (0.5-mm light chamfer finish line); Group B (1.0-mm deep chamfer finish line); and Group C (1.0-mm shoulder finish line). Marginal accuracy was evaluated by measuring the distances between each of four pairs of indentations on the crowns and on the dies with a Nikon measuring microscope.

Results

Analysis of seating measurements with parametric analysis of variance and Tukey's Studentized Range (HSD) disclosed a statistically significant difference for both tooth preparation design and die material (p< 0.001). However, the interaction effect was not significant (p=0.9073). The least marginal opening value was for FibreKor crowns made on epoxy resin dies with a light chamfer finish line (57 μm), but the difference was not statistically significantly different from crowns made on epoxy resin dies with a deep chamfer light chamfer finish line (61 μm). However, crowns made on epoxy resin dies with a shoulder finish line (81 μm) had significantly higher values (p< 0.05). FibreKor crowns made on stone dies with the shoulder finish line (95 μm) had statistically higher marginal opening values (p< 0.05). The least marginal opening value was for crowns made on stone dies with a light chamfer finish line (66 μm), but the difference was not statistically significantly different from crowns made on stone dies with a deep chamfer light chamfer finish line (70 μm).

Conclusions

Significant differences were found among the die material used for the shoulder margin design. However, there was no significant difference between light chamfer and deep chamfer margin designs for both die materials.

Citation

Ayad MF. Effect of the Crown Preparation Margin and Die Type on the Marginal Accuracy of Fiberreinforced Composite Crowns. J Contemp Dent Pract 2008 February;(9)2:009-016.

RESEARCH ARTICLE

Ezzatollah Jalalian, Hamed Jannati, Maryam Mirzaei

Evaluating the Effect of a Sloping Shoulder and a Shoulder Bevel on the Marginal Integrity of Porcelain-Fused-to-Metal (PFM) Veneer Crowns

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:17 - 24]

PDF  |  DOI: 10.5005/jcdp-9-2-17  |  Open Access |  How to cite  | 

Abstract

Aim

A porcelain-fused-to-metal (PFM) veneer crown restoration is considered successful when biological, mechanical, and esthetical concerns are satisfied. Restorations with poor marginal integrity may contribute to the cause of severe caries and periodontal defects. The most important factor in achieving successful marginal integrity is preparation design. Although a sloping shoulder preparation offers biologic and esthetic advantages over a shoulder bevel, a comparison of the marginal integrity of these two designs is less clear and is the main focus of this study.

Methods and Materials

This study was based on the analysis of 40 PFM veneer specimens fabricated on 20 stone dies. Each die had a beveled shoulder on one side of the preparation and a sloping shoulder design on the other. All specimens were selected and managed in an identical manner throughout the entire experimental process. All specimens were fabricated on stone dies made from a standard stainless steel die with the two shoulder designs in the preparation. Marginal integrity of the PFM veneers was evaluated using a scanning electron microscope to measure the gap between the restoration and tooth margin. The data were analyzed using the Student t-test at a significance level of p>0.05.

Results

An average amount of gap (± SD) for the test groups were as follows: shoulder bevel, 40.78±18.4 microns; sloping shoulder, 52.8±27.4 microns (p>0.05). All the data were within acceptable clinical range and no significant difference between two preparation designs were observed.

Conclusions

Within the limitations of this study the marginal integrity of both preparation designs were found to be similar. Since the sloping shoulder design offers biological and esthetical advantages over the shoulder bevel, its use is indicated for anterior restorations.

Citation

Jalalian E, Jannati H, Mirzaei M. Evaluating the Effect of a Sloping Shoulder and a Shoulder Bevel on the Marginal Integrity of Porcelain-Fused-to-Metal (PFM) Veneer Crowns. J Contemp Dent Pract 2008 February;(9)2:017-024.

RESEARCH ARTICLE

Bandar M. A. AL-Makramani, Abdul A. A Razak, Mohamed I. Abu-Hassan

Effect of Luting Cements on the Compressive Strength of Turkom-Cera™ All-ceramic Copings

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:33 - 40]

PDF  |  DOI: 10.5005/jcdp-9-2-33  |  Open Access |  How to cite  | 

Abstract

Aim

The objective of this study is to investigate the effect of different luting agents on the fracture strength of Turkom-Cera™ all-ceramic copings.

Methods and Materials

Standardized metal dies were duplicated from a prepared maxillary first premolar tooth using non-precious metal alloy (Wiron 99). Thirty Turkom-Cera™ copings of 0.6 mm thickness were then fabricated. Three types of luting agents were used: zinc phosphate cement (Elite™), glass-ionomer cement (Fuji I™), and a dual-cured composite resin cement (Panavia F™). Ten copings were cemented with each type. All copings were cemented to their respective dies according to manufacturer's instructions and received a static load of 5 kg for ten minutes. After 24 hours of storage in distilled water at 37°C, the copings were vertically loaded until fracture using an Instron Universal Testing Machine at a crosshead speed of 1 mm/minute. The mode of fracture was then determined.

Results

Statistical analysis carried out using analysis of variance (ANOVA) revealed significant differences in the compressive strength between the three groups (P<0.001). The mean fracture strength (in Newtons) of Turkom-Cera™ copings cemented with Elite™, Fuji I™, and Panavia F™ were 1537.4 N, 1294.4 N, and 2183.6 N, respectively.

Conclusions

Luting agents have an influence on the fracture resistance of Turkom-Cera™ copings.

Citation

AL-Makramani BMA, Razak AAA, Abu-Hassan MI. Effect of Luting Cements on the Compressive Strength of Turkom-Cera™ All-ceramic Copings. J Contemp Dent Pract 2008 February;(9)2:033-040.

RESEARCH ARTICLE

Lippo Lassila, Pekka Vallittu, Ahmed Ballo, Timo Nărhi

In vitro Mechanical Testing of Glass Fiber-reinforced Composite Used as Dental Implants

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:41 - 48]

PDF  |  DOI: 10.5005/jcdp-9-2-41  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this study was to evaluate the design of fiber-reinforced composite (FRC) on some mechanical properties of a dental implant.

Methods and Materials

FRC implants were fabricated using different polymerization conditions and designs of the glass-fiber structure. Specimens were tested with a cantilever bending test and a torsional test. The degree of monomer conversion (DC%) was measured using a Fourier transform infrared spectroscopy (FTIR).

Results

Statistical analysis showed significant differences between groups revealing mean fracture load values from 437 N to 1461 N. The mean torsional force in fracture varied from 0.01 to 1.66 Nm. The DC% varied from 50% to 90%.

Conclusion

This study suggests by modifying the polymerization conditions and fiber orientation of FRC implants, the biomechanical properties of an FRC can be tailored to the needs of dental implants.

Citation

Ballo AM, Lassila LV, Närhi TO, Vallittu PK. In vitro Mechanical Testing of Glass Fiber-reinforced Composite Used as Dental Implants. J Contemp Dent Pract 2008 February;(9)2:041-048.

RESEARCH ARTICLE

Marco Antonio Bottino, Luiz Felipe Valandro, Sarina Maciel Braga Pereira, Karla Zanini Kantorski, Aline Scalone Brentel

SEM Analysis of the in situ Early Bacterial Colonization on Two Novel Feldspathic Ceramics Submitted to Different Types of Glazing

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:49 - 56]

PDF  |  DOI: 10.5005/jcdp-9-2-49  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this study was to evaluate in situ, the early bacterial colonization on feldspar-ceramics submitted to different glazing.

Methods and Materials

Fourteen standardized disc specimens (diameter: 5 mm, thickness: 1.5 mm) of each of two micro-particulate feldspathic ceramics (VM7 and VM13, Vita) were produced according to manufacturers’ specifications for a total of 28 specimens (24 for the analysis of biofilm and 4 for topographic analysis analyzing the ceramic surfaces). Specimens from each type of ceramic were submitted to two different glazing methods composing four groups: VM7 glazed using glazing liquid Vita Akzent® 25 (G1) and glaze firing (G2), VM13 glazed using glazing liquid (G3) and glaze firing (G4). Six individuals (n=6) wore oral appliances with four ceramic specimens, fixed on the buccal face of the appliances. After 8 hours, each sample was evaluated for the presence (1) or absence (0) of bacterial colonization under a scanning electron microscope (SEM) on five randomly selected fields. The value for each sample was cumulative of the results observed in the fields. One sample from each group was evaluated under a SEM to verify the topographic pattern.

Results

There was no difference with regard to bacterial colonization between the feldspar-ceramics and between the glazing types (Kruskal-Wallis non-parametric test).

Conclusion

Feldspar-ceramics submitted to firing or glaze firing with Vita Akzent® 25 present a similar condition for in situ bacterial colonization. The similar topographic pattern of the ceramic surfaces seems to have influenced the bacterial colonization.

Citation

Pereira SMB, Kantorski KZ, Brentel AS, Valandro LF, Bottino MA. SEM Analysis of the in situ Early Bacterial Colonization on Two Novel Feldspathic Ceramics Submitted to Different Types of Glazing. J Contemp Dent Pract 2008 February;(9)2:049-056.

RESEARCH ARTICLE

Nadia Malek Taher, Yousra Al-Khairallah, Sheikha Hamed Al-Aujan, Maha Ad'dahash

The Effect of Different Light-Curing Methods on Temperature Changes of Dual Polymerizing Agents Cemented to Human Dentin

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:57 - 64]

PDF  |  DOI: 10.5005/jcdp-9-2-57  |  Open Access |  How to cite  | 

Abstract

Aim

This in vitro study aims to measure the temperature changes of resin luting cements cemented to human dentin when using different light curing systems for photo-activitation.

Methods and Materials

The three different types of light-curing units (LCUs) used for photoactivation were quartz-tungsten halogen (QTH), light emitting diode (LED), and plasma arc (PAC). Two types of dual cure resin cements were used [Variolink II™ (VL) and Choice™ (CH)]. Feltik Z250™ composite resin material was used to prepare composite discs. Thirty human dentin specimens were prepared for each resin luting cement (ten for each light source). A total of 60 specimens were fabricated. Resin cement was applied on a dentin bridge and covered with the prepared composite disc where specimens were fabricated. Temperature change was recorded with a digital thermometer. Results: The lowest temperature was recorded when VL and CH were photo-activated with the PAC unit. The PAC unit produced significantly lower recorded temperatures than the LED and QTH units. No significant difference appeared between QTH and LED units in terms of recorded temperature.

Results

The lowest temperature was recorded when VL and CH were photo-activated with the PAC unit. The PAC unit produced significantly lower recorded temperatures than the LED and QTH units. No significant difference appeared between QTH and LED units in terms of recorded temperature.

Conclusion

The PAC unit produced significantly lower temperature changes compared to QTH and LED curing units. The risk for temperature rise should be taken into consideration during photo-polymerization of adhesive resins with LED or QTH in deep cavities when dentin thickness is 0.5 mm.

Citation

Taher NM, Al-Khairallah Y, Al-Aujan SH, Ad'dahash M. The Effect of Different Light-Curing Methods on Temperature Changes of Dual Polymerizing Agents Cemented to Human Dentin. J Contemp Dent Pract 2008 February;(9)2:057-064.

RESEARCH ARTICLE

Bora Bağiş, Yildirim Bagis, Ertan Ertas, Seda Ustaomer

Comparison of the Heat Generation of Light Curing Units

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:65 - 72]

PDF  |  DOI: 10.5005/jcdp-9-2-65  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this study was to evaluate the heat generation of three different types of light curing units.

Methods and Materials

Temperature increases were recorded from a distance of 1 mm from a thermocouple to the tip of three different types of light curing units including one quartz-tungsten halogen (QTH), one plasma arc (PAC), and one light emitting diode (LED) unit. An experimental model was designed to fix the 1 mm distance between the tip of the light curing units and the thermocouple wire. Temperature changes were recorded in 10 second intervals up to 40 seconds. (10, 20, 30, and 40 seconds). Temperature measurements were repeated three times for every light curing unit after a one hour standby period. Statistical analysis of the results was performed using the analysis of variance (ANOVA) and the Bonferroni Test.

Results

The highest temperature rises (54.4±1.65°C) occurred during activation of a PAC light curing unit for every test period (p<.05). The least temperature increase (11.8±1.3°C) occurred with a LED curing unit for each tested period except for the measurement of the temperature rise using the QTH curing unit at the tenth second interval (p<.05).

Conclusion

These results indicate the choice of light activation unit and curing time is important when polymerizing light activated resin based restorations to avoid any thermal damage to the pulp.

Citation

Bagis B, Bagis Y, Ertas E, Ustaomer S. Comparison of the Heat Generation of Light Curing Units. J Contemp Dent Pract 2008 February;(9)2:065-072.

RESEARCH ARTICLE

Luci Regina P. Archegas, Danilo B. M. Caldas, Rodrigo N. Rached, Sergio Vieira, Evelise M. Souza

Sorption and Solubility of Composites Cured with Quartz-tungsten Halogen and Light Emitting Diode Light-curing Units

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:73 - 80]

PDF  |  DOI: 10.5005/jcdp-9-2-73  |  Open Access |  How to cite  | 

Abstract

Aim

The objective of this study was to evaluate the effect of light polymerization on water sorption and solubility of hybrid composites.

Methods and Materials

Three composite resins were used to make discs cured with either quartz-tungsten halogen (QTH) or light emitting diode (LED) curing units. The specimens were stored in a desiccator at 37°C and weighted to a constant mass, then immersed in deionized water for different periods of time, and reconditioned until achieving a constant mass. Sorption and solubility were calculated and subjected to analysis of variance (ANOVA) and Tukey tests (p<0.01).

Results

There were no statistically significant differences between the light sources. Water sorption increased with storage time for all the composites. The lowest sorption was observed for Herculite XRV™, followed by Tetric Ceram™, and Filtek Z250™. Increased storage times reduced the solubility of Filtek Z250™ but did not affect the solubility of Herculite XRV™ and Tetric Ceram™.

Conclusion

Water sorption and solubility of composites are not affected by the type of polymerization when the same intensity and exposure times are used. Thus, the differences found are probably related to the composition of the materials.

Clinical Significance

Water sorption and solubility of composites can lead to a shortened service life. However, these properties are not correlated to the type of polymerization.

Citation

Archegas LRP, Caldas DBM, Rached RN, Vieira S, Souza EM. Sorption and Solubility of Composites Cured with Quartz-tungsten Halogen and Light Emitting Diode Light-curing Units. J Contemp Dent Pract 2008 February;(9)2:073-080.

RESEARCH ARTICLE

Flávia Martão Flório, Cinthia Maria Barbosa, Robson Tetsuo Sasaki, Robera Tarkany Basting

Influence of Time on Bond Strength After Bleaching with 35% Hydrogen Peroxide

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:81 - 88]

PDF  |  DOI: 10.5005/jcdp-9-2-81  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this in vitro study was to evaluate the influence of time after treatment with a 35% hydrogen peroxide bleaching agent on the shear bond strength between composite resin and sound enamel and dentin.

Methods and Materials

Eighty dental slabs - 40 enamel (E) slabs and 40 dentin (D) slabs - were embedded, flatted, and divided into four groups (n=10). In G1 the E and D slabs were kept in artificial saliva for 14 days. For the G2, G3, and G4 groups the E and D slabs were submitted to bleaching treatment with a 35% hydrogen peroxide bleaching agent. At different times after bleaching treatments (G2=immediate; G3=seven days; G4= fourteen days), composite resin cylinders were made using an adhesive system. Tests were performed in a universal testing machine at a speed of 0.5 mm/min to obtain the values in MPa.

Results

For enamel, the Kruskal-Wallis test and Dunn Method showed G1 differed significantly from G2 (G1=13.40 a; G2=6.64 b; G3=16.76 a; G4=11.64 ab). For dentin, the analysis of variance (ANOVA) and Tukey tests showed that G1 differed significantly from G2 and G3 (G1=12.11 a; G2=4.97 b; G3=8.67 c; G4=11.86 ac).

Conclusion

It is recommended adhesive restorative procedures in enamel be delayed for seven days postbleaching treatment with 35% hydrogen peroxide, while restorations in dentin should be delayed for 14 days following bleaching treatment.

Citation

Barbosa CM, Sasaki RT, Flório FM, Basting RT. Influence of Time on Bond Strength After Bleaching with 35% Hydrogen Peroxide. J Contemp Dent Pract 2008 February;(9)2:081-088.

RESEARCH ARTICLE

Mário Alexandre Coelho Sinhoreti, Simonides Consani, Lourenço Correr-Sobrinho, Dario Segreto, William Cunha Brandt

Influence of Irradiance on the Push-out Bond Strength of Composite Restorations Photoactivated by LED

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:89 - 96]

PDF  |  DOI: 10.5005/jcdp-9-2-89  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this study was to compare the bond strength of resin composites to dental structure photoactivated with a light emitting diode (LED) curing unit.

Methods and Materials

One hundred bovine incisors were selected and a conical cavity was prepared in the facial surface of each tooth. Clearfil SE Bond (Kuraray CO., LTD. Osaka, Japan) adhesive system was applied, and the cavities were filled with a single increment of Filtek™ Z250 (3M ESPE, St. Paul, MN, USA) or Esthet-X (Dentsply-Caulk – Mildford, DE, USA). The specimens were assigned to ten groups (n=10) according to the irradiance used: 100, 200, 300, 400, or 500 mW/cm2. Photoactivation was accomplished using an Ultrablue IS LED (DMC Equipamentos LTDA, São Carlos, SP, Brazil). The radiant exposure time was kept constant. A push-out test was conducted in a universal testing machine. Bond strength values were submitted to a two-way analysis of variance (ANOVA) and a Tukey's test at the 5% significance level.

Results

The bond strength of the Z250 was higher than the Eshet-X (p<0.05). However, the modulation of irradiance adjusted to the same radiant exposure had no influence on Z250. The bond strength using an irradiance of 100mW/cm2 was higher than the other levels for Esthet-X. When composites were compared, no significant differences were detected between them for activation with irradiances of 100 and 200 mW/cm2.

Conclusion

The modulation of the luminous energy emitted by LED was almost unable to provide significant differences among the groups for both composites, except for a lower irradiance of Esthet-X.

Citation

Segreto D, Brandt WC, Correr-Sobrinho L, Sinhoreti MAC, Consani S. Influence of Irradiance on the Push-out Bond Strength of Composite Restorations Photoactivated by LED. J Contemp Dent Pract 2008 February;(9)2:089-096.

RESEARCH ARTICLE

Horieh Moosavi, Marjaneh Ghavamnasiri

The Effect of Different Adhesive Systems on the Retention Strength of Bonded Amalgam Restorations

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:97 - 104]

PDF  |  DOI: 10.5005/jcdp-9-2-97  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this study was to evaluate the bond strength of bonded amalgam to dentin when unfilled and filled adhesive systems are employed using different application modes and to compare the adhesives with a cavity varnish and unlined restorations.

Methods and Materials

One hundred twenty sound third human molar teeth were used in the study. A cylindrical cavity 3.3 mm in diameter was prepared in a cross section of dentin approximately 3.0 mm in thickness. The specimens were divided into six experimental groups (n=20) according to the cavity liner used in the prepared cylindrical cavity: One Coat Bond™ (O), Scotchbond Multi-Purpose™(S), Panavia 21™ (Pa), PQ1™ (P), Copalite™ (C), and the unlined (U) group which served as the control group. Cavity surfaces were treated with the assigned adhesive/liner according to manufacturer's instructions then restored with amalgam. After storage in saline solution for seven days at 370C, the specimens were subjected to a push-out test at a crosshead speed of 1 mm/min. The mode of failure was assessed by microscopic analysis of the fracture sites. Data were analyzed by analysis of variance (ANOVA) and Duncan Multiple range tests (α=0.05).

Results

No significant difference in amalgam-dentin bond strength was found among O (23.47 MPa), S (21.02 MPa), and Pa (20.06 MPa) adhesive groups, but there was a significant difference between each of these groups and the P and C groups. The U group exhibited significantly lower retention than the other groups (P<0.05).

Conclusion

Different bond strengths were observed with the different types of dentin bonding agents and liners employed. The lowest bond strength was seen in the U group.

Clinical Significance

A statistically significant difference in bond strength was observed with O, S, and Pa compared to P, but this finding is not sufficient to rely on the bonding of amalgam to dentin, particularly in complex amalgam restorations.

Citation

Ghavamnasiri M, Moosavi H. The Effect of Different Adhesive Systems on the Retention Strength of Bonded Amalgam Restorations. J Contemp Dent Pract 2008 February;(9)2:097-104.

RESEARCH ARTICLE

Soodabeh Kimyai, Hadi Valizadeh

Comparison of the Effect of Hydrogel and a Solution of Sodium Ascorbate on Dentincomposite Bond Strength After Bleaching

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:105 - 112]

PDF  |  DOI: 10.5005/jcdp-9-2-105  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this study was to compare the effects of solution and different sodium ascorbate hydrogels on dentin-resin composite shear bond strength subsequent to a bleaching procedure with 10% carbamide peroxide.

Methods and Materials

Sixty buccal dentin surfaces obtained from intact human third molars were randomly divided into five groups (n=12). Dentin surfaces received different treatments: (1) no treatment; (2) bleaching (10% carbamide peroxide gel); (3) bleaching + 10% sodium ascorbate solution; (4) bleaching + 10% sodium ascorbate hydrogel, and (5) bleaching + 20% sodium ascorbate hydrogel. Dentin surfaces were bonded with Single Bond™ and restored with a composite (Z100). The samples were tested for shear bond strengths. Data was analyzed using analysis of variance (ANOVA) and Tukey tests.

Results

Significantly higher bond strengths were observed subsequent to treatment with hydrogel and solution forms of sodium ascorbate (p<0.05). No significant differences were demonstrated between different forms of sodium ascorbate preparations. In addition, no significant differences were observed among groups with antioxidant treatment (Groups 3, 4, and 5) and Group 1 (no treatment).

Conclusion

Reduced bond strength to bleached dentin can be amended by the use of sodium ascorbate as an antioxidant.

Clinical Significance

Both hydrogel and solution forms of sodium ascorbate can significantly improve the reduced bond strength of resin composite to dentin subsequent to a bleaching procedure with 10% carbamide peroxide.

Citation

Kimyai S, Valizadeh H. Comparison of the Effect of Hydrogel and a Solution of Sodium Ascorbate on Dentin-composite Bond Strength After Bleaching. J Contemp Dent Pract 2008 February;(9)2:105-112.

RESEARCH ARTICLE

Marjaneh Ghavamnasiri, Mahshid Bagheri

Effect of Cavosurface Margin Configuration of Class V Cavity Preparations on Microleakage of Composite Resin Restorations

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:122 - 129]

PDF  |  DOI: 10.5005/jcdp-9-2-122  |  Open Access |  How to cite  | 

Abstract

Aim

The aim of this study was to compare the marginal leakage of hybrid and microfilled composite resin in Class V restorations with and without an enamel bevel.

Methods and Materials

Fifty-six cavities were prepared on the buccal and lingual surfaces of 28 extracted human molars using a round bur with the dimensions of 3×2×1.5 mm. The specimens were divided into two groups of 28 based on the cavosurface margin configuration (beveled and non- beveled). Each group was then divided into two subgroups (n=14) based on the type of composite resin (microfilled and hybrid) used for restoration. After completing restorative procedure, specimens were thermocycled and immersed in 0.5% basic fuchsine. Samples were embedded in polyester and then sectioned both mesiodistally and buccolingually. Dye penetration was observed with a stereomicroscope at 25x magnification. Statistical nonparametric analysis Kruskal-Wallis and Mann-Whitney tests were performed to compare the data (a=0.05).

Results

There was no statistically significant difference between the two types of composites and two types of enamel margins with respect to microleakage (P>5%). The degree of microleakage at the gingival margin located in dentin of each group was more than that of the enamel margin (P<5%).

Conclusion

An enamel bevel in a Class V cavity preparation had no effect on the reduction of marginal leakage using either hybrid or microfilled composite resin.

Citation

Bagheri M, Ghavamnasiri M. Effect of Cavosurface Margin Configuration of Class V Cavity Preparations on Microleakage of Composite Resin Restorations. J Contemp Dent Pract 2008 February; (9)2:122-129.

RESEARCH ARTICLE

A. R. Prabhaker, O. S. Raju, Ameet J. Kurthukoti, V. Satish

Evaluation of the Clinical Behavior of Resin Modified Glass Ionomer Cement on Primary Molars: A Comparative One-year Study

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:130 - 137]

PDF  |  DOI: 10.5005/jcdp-9-2-130  |  Open Access |  How to cite  | 

Abstract

Aim

The objectives of the present study were to evaluate and compare the clinical behavior of resin modified glass ionomer cement (RMGIC) on primary molars with conventional and modified cavity preparations.

Methods and Materials

Forty-two children, 5-9 years of age, having bilateral initial occlusal caries on the mandibular primary second molars were selected for the study. A split mouth design was employed where conventional Class I cavities with a 90° cavosurface angle were prepared randomly on primary second molars on one side and modified cavities with a 1 mm straight bevel along the cavosurface margin on the contra-lateral side. These cavities were restored with RMGIC. The restorations were evaluated during subsequent visits, for a period of one year.

Results

At the end of one year, 90% of the restorations survived in the conventional cavity group whereas 100% of the restorations survived in the modified cavity group.

Conclusion

Incorporation of a bevel in Class I cavities increases the survival rate of RMGIC restorations. There was no significant difference in the clinical behavior between the two groups. However, beveling does contribute to long term clinical success of these restorations.

Clinical Significance

Incorporation of a straight bevel in conventional cavities will improve the retention of RMGIC by increasing the bonding area and enhancing the desired properties of the material.

Citation

Prabhakar AR, Raju OS, Kurthukoti AJ, Satish V. Evaluation of the Clinical Behavior of Resin Modified Glass Ionomer Cement on Primary Molars: A Comparative One-year Study. J Contemp Dent Pract 2008 February;(9)2:130-137.

RESEARCH ARTICLE

Richard Koh, Gisele Neiva, Joseph Dennison, Peter Yaman

Finishing Systems on the Final Surface Roughness of Composites

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:8] [Pages No:138 - 145]

PDF  |  DOI: 10.5005/jcdp-9-2-138  |  Open Access |  How to cite  | 

Abstract

Aim

This study evaluated differences in surface roughness of a microhybrid (Gradia™ Direct, GC America) and a nanofil (Filtek™ Supreme, 3M™ ESPE™) composite using four polishing systems: PoGo™/Enhance® (DENTSPLY/Caulk), Sof-Lex™ (3MTM ESPE™), Astropol® (Ivoclar Vivadent), and Optidisc™ (KerrHawe).

Methods and Materials

An aluminum mold was used to prepare 2 X 60 composite disks (10 mm X 2 mm). Composite was packed into the mold, placed between two glass slabs, and polymerized for 40 seconds from the top and bottom surfaces. Specimens were finished to a standard rough surface using Moore's disks with six brushing strokes. Specimens were rinsed and stored in artificial saliva in individual plastic bags at 36°C for 24 hours prior to testing. Specimens were randomly assigned to one of the four polishing systems and were polished for 30 seconds (10 seconds per grit) with brushing strokes according to the manufacturer's instructions. Mean surface roughness (Ra) was recorded with a surface-analyzer 24 hours after storage in artificial saliva, both before and after polishing. Means were analyzed using two-way and one-way analysis of variance (ANOVA) and Tukey multiple comparison tests at p < 0.05.

Results

There was a statistically significant difference for baseline measures between Filtek™ and Gradia™ (p=0.0338). For Filtek™, Sof-Lex™ provided a significantly smoother surface (Ra=0.80 ± 0.21) than Optidisc™ (Ra=0.93 ± 0.28), Astropol® (Ra=1.15 ± 0.24), and Pogo™/Enhance® (Ra=1.39 ± 0.39). For Gradia, Sof-Lex™ provided a significantly smoother surface (Ra=0.47 ± 0.09) and Astropol® provided a significantly rougher surface (Ra=1.39 ± 0.19) than Pogo™/Enhance® (Ra=1.11 ± 0.20) and Optidisc™ (Ra=1.15 ± 0.18). There was no significant difference in roughness between composites for individual polishing systems (p=0.3991).

Conclusion

Filtek™ specimens were smoother than Gradia™ specimens after baseline roughening. Sof- Lex™ provided the smoothest final surface when used with either composite. Astropol® provided a rough surface for Gradia™ specimens.

Citation

Koh R, Neiva G, Dennison J, Yaman P. Finishing Systems on the Final Surface Roughness of Composites. J Contemp Dent Pract 2008 February;(9)2:138-145.

RESEARCH ARTICLE

Lucianne Cople Maia, Livia Azeredo A. Antunes, Áurea Simone Barrôso Vieira, Márcia Peraira Alves dos Santos

Influence of Kinetic Cavity Preparation Devices on Dental Topography: An in vitro Study

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:9] [Pages No:146 - 154]

PDF  |  DOI: 10.5005/jcdp-9-2-146  |  Open Access |  How to cite  | 

Abstract

Aim

The objectives of this study were to assess the influence of four different kinetic cavity preparation devices on cavity preparation taking into account tip angulation, internal tip diameter, and distance to the dental substrate. The dental topography itself was also evaluated after the use of these devices.

Methods and Materials

Quantitative parameters using pertinent statistical tests as well as qualitative parameters were used to assess the topography in terms of the dispersion halo effect (DHE), size, and depth of the preparation.

Results

The DHE did not present differences among the groups. In relation to the preparation size, the internal diameter influenced 120° point angles, whereas distance influenced the 90° ones. Considering the preparation depth, the 90° point angle yielded the deepest. In the qualitative analysis, both angles provided cavity preparations with rounded cavosurface angles. The 120° point angles yielded inclined, shallow V-shaped preparations, whereas the 90° angles presented U-shaped preparations reaching the dentin. The enamel had an irregular aspect and exposed prisms; dentin had a loose smear layer with aluminum oxide residues.

Conclusion

The kind of device may influence the kinetic cavity design.

Clinical Significance

It is the clinician that knows how to select the appropriate devices to adopt in order to achieve the desired cut, depth, and shape of cavity preparations.

Citation

Antunes LAA, Vieira ASB, Alves dos Santos MP, Maia LC. Influence of Kinetic Cavity Preparation Devices on Dental Topography: An in vitro Study. J Contemp Dent Pract 2008 February;(9)2:146-154.

RESEARCH ARTICLE

Hervé Tassery, Stephen Koubi

Minimally Invasive Dentistry Using Sonic and Ultra-sonic Devices in Ultraconservative Class 2 Restorations

[Year:2008] [Month:February] [Volume:9] [Number:2] [Pages:11] [Pages No:155 - 165]

PDF  |  DOI: 10.5005/jcdp-9-2-155  |  Open Access |  How to cite  | 

Abstract

Aim

Within the context of minimally invasive dentistry this article describes the sonic and ultrasonic cavity preparation techniques and assesses their advantages and disadvantages, clinical difficulties of their use, and offers a statement about these devices.

Background

Ultra-conservative Class 2 restorative techniques require the use of devices such as sonic and the new ultrasonic preparation systems. These systems, featuring a series of sonic and new ultra-sonic inserts, allow for the fabrication of preventive preparations on proximal surfaces without injuring the adjacent proximal surface or damaging the marginal ridge.

Review

An ultraconservative approach to the restoration of teeth with proximal caries that lack frank occlusal cavitation is facilitated by the use of slot-style cavity preparations created with sonic and ultrasonic instrumentation, and esthetic restorative materials.

Summary

New restorative procedures appear suitable for use in ultraconservative restorative dentistry. More frequent use of these procedures by dental practitioners could prevent the traditional breakdown of the marginal ridge when preparing a Class 2 dental restoration. When cautiously used, these two ultraconservative devices provide alternative operative procedures to treat carious lesions without frank occlusal cavitation and to promote another aspect of preventive dentistry.

Clinical Significance

New restorative procedures appear suitable for use in ultraconservative restorative dentistry. More frequent use of these procedures by dental practitioners could prevent the traditional breakdown of the marginal ridge when preparing a Class 2 dental restoration.

Citation

Koubi S, Tassery H. Minimally Invasive Dentistry Using Sonic and Ultra-sonic Devices in Ultraconservative Class 2 Restorations. J Contemp Dent Pract 2008 February;(9)2:155-165.

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