Rajiv gandhi university of health sciences



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RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES

BANGALORE, KARNATAKA


Proforma for

Registration of Subjects for Dissertation


  1. Name of the candidate and address:


Dr.Sangeetha Lakshmi

I year M.D.S student

Department of Prosthodontics

A.E.C.S Maaruti College of Dental

Sciences and Research Centre

108, Tank bund road, Hulimavu,

BTM 6th stage, 1st phase,

Bannerghatta road, Bangalore – 76



2. Name of the institution
A.E.C.S Maaruti College of

Dental Sciences and Research

Centre; Bangalore
3. Course of the study and subject
Master of Dental Surgery (MDS)

Prosthodontics
4. Date of admission to the course

24-5-2010
5. Title of the topic

Effect of cyclic loading on the tensile bond strength of luting cements

used in cement retained implant prosthesis

6. Brief resume of the intended work

6.1 Need for the study

Edentulous conditions are increasingly treated with implant-supported prosthesis. Many current implant systems have abutments on which super structures are cemented. The type of cement used affects the retentive characteristics of the prosthesis. Retrievability of the prosthesis is desirable if intervention therapy is required for the maintenance of the supporting tissue and implant. The tensile strength of luting cement should allow retrieval of the prosthesis when required, yet be sufficient to retain the prosthesis in place during function. Cement retained prosthesis very offen loose the retention due to the failure of luting cement retention. Relationship between number of masticatory cycles and retentive forces is not adequately documented. Hence it was decided to find out the effect of cyclic loading on tensile bond strength of luting agents used in cement retained implant prosthesis.


6.2 Review of literature
6.2.1.Ramp MH, Dixan DL, Ramp LC, Breeding LC1et al compared the tensile bond strength of six provisional luting agents when used with superstructures cemented on implants. Ten prefabricated implant abutments with 30 taper and chamfer margins and 10 implant analogs (Steri-oss) were used. Each analog was stabilized in a resin block and a t-nut was embedded in the base of the acrylic resin for attachment to the tensile testing apparatus. Each screw-retained abutment was attached to the implant analog with 35 Ncm torque and access opening was filled with polyvinyl siloxane putty. Platinum foil was adapted over the abutment to simulate die spacer. Polyvinyl siloxane impression of the model was made to fabricate a stone die. On this die wax copings were formed and casted in palladium-silver metal. Ten castings were fabricated. Four commercially available provisional luting agents (Neo-Temp, Temp-Bond, Provilink, IRM) and one prototype polyurethane luting agent (Steri-Oss) were evaluated. Temp-Bond luting agent served as the control. Each casting was placed with finger pressure for 5 seconds. The specimens were then subjected to a 6 kg load for 10 minutes. Specimens were stored in distilled water at 37°C for 48 hours before testing. Each specimen was attached to a Universal testing machine and a load of 500 kg at a crosshead speed of 0.5 cm/min was applied. Each luting agent group was tested and then the samples were cleaned and retested with the next luting agent. Tensile bond strengths ranged between 1.29 and 4.08 MPa. The lowest tensile bond strengths were found to be statistically similar between Temp Bond 1.29MPa and Provilink 1.31MPa luting agents. Neo-Temp exhibited the highest tensile bond strength of 3.04 MPa. It was concluded that Temp bond allowed easy retrieval when required and showed adequate retention of the prostheses during function.
6.2.2. Ongthiemsak C, Mekayarajjananoth T, Winkler S and Boberick K G 2 evaluated the effect of compressive cyclic loading on the retentive forces of a temporary cement used in implant crowns and also the relationship between load cycles and retentive forces. Masticatory forces cause fatigue to cement-retained crowns and abutments and this may adversely affect retention. Ten castings and implant abutments were cemented with zinc oxide-eugenol temporary cement. The retentive force necessary to dislodge the casting from the abutment was determined before and after the application of 2 Hz of vertical off-axis 3-mm sinusoidal-type compressive cyclic loading between 20 and 130 N for 500 000, 1 000 000, and 5 000 000 cycles. Duration was equivalent to approximately 6 months, 1 year, and 5 years of human mastication. Compressive cyclic loading reduced the retentive forces significantly in all the groups. The retentive forces were reduced by 16.75%, 18.73%, and 19.68% during the load cycles . Although cyclic loading reduced the retention, the increased cycles had little corelation to the decreased retentive forces of the temporary cement. The results of this investigation suggest vertical off-axis loading can significantly reduce the quality of zinc oxide -eugenol temporary cement to retain crowns on implant abutments.
6.2.3. Karl M, Graef F, Taylor TD and Heckmann MS 3 compared the difference in the number of chipping fractures between screw retained ceramic veneered implant fixed partial dentures (FPD) and cement retained restorations during dynamic cyclic loading on the occlusal surface.10 cement- retained and 10 screw- retained ceramic veneered 5 unit FPDs were used in 3 implant situation. Three implants of 4.1 mm diameter were placed in epoxy resin model in a straight line configuration with a bone sink depth of 12 mm. Ten cement- retained and 10 screw -retained 5 unit FPDs were waxed and casted with precious metal alloy. Cement-retained FPDs were fixed using provisional cement, and screw retained FPDs were fixed with occlusal screws, with a torque of 15N cm. The models were mounted in a water bath maintained at 370 C in a masticatory simulator. 3 ceramic blocks were used to serve as antagonist. Masticatory simulator was used for loading the occlusal surface of FPDs for 20,000 cycles with a force of 100N applied for 1 second followed by 1 second of no loading. The FPDs were evaluated using light microscope and a dental probe. Under cyclic loading more number of chipping fractures were found on occlusal surfaces of screw retained implant restorations with unfilled holes (2.20) compared to cement retained restorations (1.57). In screw retained FPDs screw access holes form a discontinuity of the ceramic layer and may be an origin for chipping fractures.
6.2.4. Pan Y and Lin C 4 evaluated the retention of seven different luting agents

(Panavia F, Zinc phosphate cement, Advance, Improve and All –Bond 2- Definitive cements; Durelon and Temp-Bond – Provisional cements ) when used with cement retained implant abutment/analog assemblies along with superstructures. Fifty six Steri-oss titanium abutments of 3.8 mm diameter with titanium screws and implant analog were used. To provide an even thickness for the luting agent, a 0.001-inch thick platinum foil was adapted onto the abutment surface as a die spacer. This assembly was duplicated with silicon material and cast was poured. An 8mm diameter flat occlusal surface wax superstructure was fabricated to facilitate testing using split mold technique. Mounting jigs were fabricated to house the abutment/analog assemblies and to facilitate placement within a masticatory simulator. Seven different luting agents were used for cementation of crowns. 2 kg load was applied for 1hour after cementation. These samples were kept in an oven kept at 370 C and 100% humidity for another 23 hours. All specimens were subjected to 100,000 cycles at 1.2 hz in the chewing machine with a force of 75 N which is equal to 3 years of chewing. After cyclic loading uniaxial tensile force was applied to the abutment/crown complex by a swivel hook, which was attached to the upper member of universal testing machine. Another customized jig with a loop and three side screws was fabricated to retain the superstructures. All-Bond 2 resin cement showed the highest cement failure load at 1.4MPa followed by Panavia F failing at 1.5MPa with no significant difference between them. Temp-Bond had the lowest cement failure load of 0.2MPa and there was no significant difference between Temp-Bond and Improv which failed at 0.3MPa. It was concluded that definitive cements showed more retention than provisional cements. Definitive luting agents like zinc phosphate cement and resin cement should be selected for planned cementation of definitive fixed prostheses without possible retrieval and provisional luting agents such as eugenol based cements should be used when possible retrieval is expected for future maintenance.


6.2.5.Heintze S.D, Cavalleri A, Zellweger G, Buchler A et al 5compared the frequency of failures (complete fractures or partial cracks) of molar crowns made of two different all-ceramic materials (IPS Empress and e.max) during dynamic loading and static loading in a chewing simulator, fixed with different luting agents. 144 molar crowns were fabricated from each of the all ceramic materials. Wax patterns were made and mould was prepared with lost wax technique. The mould was filled with IPS Empress at

10750 C and e.max press EXP at 9250C in a furnace. The PMMA abutments were sandblasted with 1 bar pressure and 100 μm Al2O3. The inner surfaces of all the crowns were acid etched with hydrofluoric acid. Half of the crowns were adhesively luted on standardized CAD/CAM milled PMMA abutments with Variolink II (resin cement) and the other half of the crowns with Vivaglass PF (Glass-ionomer cement). After seating of the crowns and removal of cement excess, the composite was light-cured on all four crown sides for 30s each. After cementation, all the crowns were stored in water at 37°C for 24 hours prior to wear simulation. A stainless steel ball (diameter 10 mm) was used as the stylus. It was positioned on the molar crowns to achieve contacts on both the mesio-buccal and mesio-lingual cusp. The different loading protocols were chosen to define different scenarios for testing all-ceramic materials- a steady force of 100 N; a gradual increase of force between 40-60-80-100N and an increase as well as decrease of force between 40-100-40N. All the different phases were run for 100,000 cycles. Sinusoidal and rectangular force profiles were used. Fractures and cracks were noticed in the IPS Empress test groups. In the 144 IPS Empress crowns, 9 complete fractures and 3 partial cracks were observed, which corresponds to a fracture frequency of 6.25% and crack frequency of 2.1%. Fractures were seen more when the sinusoidal force profile was applied compared to a rectangular force profile. In addition, more fractures occurred in the IPS Empress crowns that were luted with GIC than in those that were adhesively luted. However this difference was not statistically significant. The frequency of fractures and/or cracks was not related to a specific loading protocol. For the static fracture load, there was no statistically significant difference between adhesively luted Empress crowns and GIC-luted e.max Press Exp crowns. However, during dynamic loading, fractures and/or cracks occurred only in IPS Empress crowns irrespective of the loading protocol and luting cements. It was concluded that e.max crowns luted with adhesive cement showed more resistance to fracture and crack compared to IPS Empress.


View Within Article
View Within Article6.3 Objectives of the study:

To compare the tensile bond strength of two different cements viz. zinc oxide eugenol cement and zinc phosphate cement used in cement retained implant prosthesis before and after cyclic loading.


7. Materials and methods

7.1 Source of data

Experiments will be conducted to determine the effect of cyclic loading on the tensile bond strength of two luting cements used in cement retained implant prosthesis. The results compiled will serve as the main source of data.
Materials:

1. Typodont jaw with hinge axis (Confident)

2. Implants and abutments (ADIN implant system )

3. Magnets (1.7 mm diameter and 0.5 mm thickness with repelling power of 137 N)

4. Zinc oxide eugenol temporary cement (Temp bond)

5. Zinc phosphate cement (Detray)

6. All ceramic prosthesis (E-max )

7. Surveyor (Ney surveyor)


Equipments:

1. Servo hydraulic machine (Instron-5582) - for the application of cyclic loading.

2. Universal testing machine (Instron- 5582)-to measure the tensile bond strength.

7.2. Methodology

Preparation of specimens:

7.2.1. Placement of implants and abutments

Implants will be placed parallel to each other on the typodont jaw in 45 and 47 region using a surveyor. Implant will be fixed to the jaw with self cure acrylic resin. Analysing rod will be fixed on the abutments and that will ensure parallel placement of implant fixture. This assembly will be stored in water for 24 hours.


7.2.2 .Preparation of implant abutments and opposing teeth:

Abutment height will be adjusted by milling to obtain adequate space for the prostheses. Two separate All ceramic three unit fixed dental prosthesis (E-Max) will be fabricated to be used along with the two different types of cements. Opposing teeth 15, 16 and 17 will be prepared to receive individual All- ceramic crowns (Fig 7). Occlusion will be adjusted to match with the opposing, adjacent and contra lateral sides. To standardize the contact Bausch spray will be used.


7.2.3. Cementation of the prosthesis:

Prostheses will be fixed using zinc oxide eugenol temporary cement and zinc phosphate permanent cement. Occlusion will be re evaluated. Model will be stored at room temperature for 24 hrs.




Test for tensile bond strength

After 24 hrs typodont jaw will be attached to the universal testing machine, and the fixed prosthesis will be subjected to tensile loading. Values obtained will serve as control. The bridges will then be cleaned off the cement using ultrasonic cleaner and the cementation process will be repeated. Prostheses will be subjected to cyclic loading using Servo hydraulic machine with 600 N force load for 80,000/ 1,60,000/ 2,40,000 cycles simulating 1,2 and 3 months of mastication (Fig 11). In separate experiments the specimens which will be undergoing the loading cycles and tensile bond strength of the luting cement will be measured (Fig9). The difference in the values will be considered as the effect of load cycles on the tensile bond strength of the cements.


Statistical analysis

The results obtained will be subjected to Factorial ANOVA to detect statistically significant difference.



Methodology

All ceramic (3 unit) fixed prosthesis for dental implant

dental





Cementation

dental





Zinc oxide eugenol cement

dental


Zinc phosphate cement

dental





Tensile bond strength evaluation

dental





Recementation

dental





Cyclic loading 80,000/ 1,60,000 / 2,40,000







Tensile bond strength evaluation

dental





Results






Statistical analysis

7.2 Does the study require any investigations or interventions to be conducted on patients or other humans or animals?

No


    1. Has ethical clearance been obtained from your institute ?

Yes


    1. Trial test done if any ?

Yes
8. Signature of the candidate
9. Remarks of the guide ;

This is a clinically relevant study which might arise useful

information on the prognostication of dental implant therapy

10. Name and designation of


10.1 Guide - Dr. K Chandrasekharan Nair, Professor of Prosthodontics
10.2 Signature

10.3 Co- Guide - Dr. Divya Hegde, Associate Professor


10.4 Signature
10.5 Head of the department Dr. K Chandrasekharan Nair
10.6 Signature
11.1 Remarks of the principal
11.2 Signature

List of references:



  1. Ramp M H, Dixon D L, Ramp L C, Breeding L C et al. Tensile bond strength of provisional luting agents used with an implant system.

J Prosthet Dent 1999;81:510-4.

  1. Onghiemsak C, Mekayarajjananonth T, Winkler S and Boberick K. The effect of compressive cyclic loading on retention of a temporary cement used with implant. J Oral Implantology,2005;31(3):114-9.

  2. Pan Y and lin C. The effect of luting agents on the retention of dental implant-supported crowns.

Chang Gung Med J 2005;28:403-10.

  1. Karl M, Graef F, Taylor T.D and Heckmann S.M. In vitro effect of load cycling on metal-ceramic cement-and screw-retained implant restorations.

J Prosthet Dent 2007;97:137-40.

  1. Heintze SD, Cavallrey A; Zellweger G, Buchler A. Fracture frequency of all ceramic crowns during dynamic loading in a chewing simulator using different loading and luting protocols.

J Dent mat 2008;24: 1352-61.

REPORT ON THE PILOT STUDY:

Effect of cyclic loading on the tensile bond strength of luting cement used in cement retained implant prosthesis .
Objectives of the study: To find out the tensile bond strength of zinc oxide eugenol cement used in cement retained implant prosthesis before and after cyclic loading.
Methodology:

Following materials were used in this study:

1. Typodont jaw with hinge axis(Confident)

2. Implants and abutments (ADIN implant system)

3. Magnets (1.7 mm diameter and 0.5 mm thickness with repelling power of 137 N)

4. Zinc oxide eugenol temporary cement (Temp bond)

5. Zinc phosphate cement (Detray)

6. All ceramic prosthesis (E-max)

7. Surveyor (Ney surveyor)
Implants were placed mutually parallel on the typodont jaw in 45 and 47 region using a surveyor. Implant was fixed to the jaw with self cure acrylic resin. Analysing rod was fixed on the abutments to place them parallel on the implant fixture. This assembly was stored in water for 24 hours. Abutment height was adjusted by milling to obtain adequate space for the prosthesis. One All ceramic three unit fixed dental prosthesis

(E-Max) was fabricated to be used with ZOE cement. 15, 16 and 17 were prepared to receive individual All- ceramic crowns. Occlusion was adjusted to match with the opposing, adjacent and contra lateral sides. To standardize the contact Bausch spray was used. Prosthesis was fixed using zinc oxide eugenol temporary cement. Occlusion was re evaluated. Model was stored at room temperature for 24 hrs and then typodont jaw was attached to the universal testing machine and the fixed prosthesis will be subjected to tensile loading. These values obtained served as control. The bridge was cleaned off the cement using ultrasonic cleaner and cementation process was repeated. Prosthesis was subjected to cyclic loading using Servo hydraulic machine with 600 N force load for 10,000; 20,000; cycles simulating 1,2 weeks of mastication. The specimens which have undergone the loading cycles were subjected to tensile loading to measure the tensile bond strength of the luting cement. The difference in the values was considered as the effect of load cycles on the tensile bond strength of the cements.



Results
Tensile bond strength of ZOE cement (MPa)

Before cyclic loading



After cyclic loading

10,000

20,000

5


5





4.9


Observations

1.Tensile bond strength of ZOE temporary cement before cyclic loading was -5 MPa

2. Tensile bond strength of ZOE temporary cement after 10,000 cycles was-5MPa

3. Tensile bond strength of ZOE temporary cement after 20,000 cycles was

reduced to- 4.9MPa

Conclusion

Cyclic loading can weaken the cement on progressive application.






















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