Rajiv Gandhi University of Health Sciences, Karnataka s11

RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES, KARNATAKA BANGALORE ANNEXURE-II PROFORMA FOR REGISTRATION OF SUBJECT FOR DISSERTATION 1. Name of the candidate DR. VIMAL GALA [In block letters] Permanent address B-24, Jalaram Ashish, Devidayal Road, Mulund (west), Mumbai-400080.

2. Name of the institution HKE’s S.N. Institute of Dental sciences, Gulbarga-585105, Karnataka

3. Course of the study and Master Of Dental Surgery [MDS] subjects Prosthodontics And Crown And Bridge.

4. Date of admission to the 03-05-10 course 5. Title of the Topic Comparison of the dimensional accuracy and bond strength of combined reversible- irreversible hydrocolloid impression system with the other commonly used impression materials - an in-vitro study. 6. Brief Resume of the Intended work

NEED FOR THE STUDY Agar, as an impression material when used has the disadvantage of long time for manipulation and cumbersome equipment. A modification to the agar impression is the combined agar alginate technique (laminate technique). The hydrocolloid in the tray is replaced with a mix of alginate which bonds with the agar expressed from a syringe. The alginate gels by a chemical reaction whereas the agar gels by means of contact with the chilled alginate. Since, the agar and not the alginate will be in contact with the prepared teeth, maximum detail is reproduced. When agar is used individually as an impression material, the pre impression procedure is time consuming. It requires constant monitoring of the water level of hot water bath, the time and temperature, etc. But in the laminate technique, these disadvantages are eliminated making the procedure user friendly; as only the syringe material needs to be heated, equipment cost is lower and less preparation time is required. Studies have been done earlier in the literature to compare the accuracy of this technique in the 1980s. the advancement in the elastomeric materials; agar is very rarely available in India as an impression material and is used only as a duplicating medium in the laboratories. Hence, this in vitro study is an attempt to evaluate and compare the dimensional accuracy of the present day available agar syringeable products combined with alginates to that of the other impression materials which are used commonly in the dental clinics.

REVIEW OF LITERATURE Johnson GH, Craig RG This study was done to compare the dimensional accuracy and the bond strength of combination of 4 products of irreversible hydrocolloid and 3 products of reversible hydrocolloid. In general, there was little difference in the accuracy among the agar hydrocolloids. Of the alginate hydrocolloids, products Jeltrate and Coe alginate produced the most accurate casts in combination with any of the agar hydrocolloids. Considering both bond strength and accuracy, product Coe alginate in combination with either Denloid brown or Dentloid Green produced the best overall results.

Linke BA, Nicholls JI, Faucher RR A study was conducted to compare the distortion analysis of stone casts made from the impression materials used commonly. Reversible hydrocolloid impression material produced significantly less interabutment distortion than the irreversible hydrocolloid. Statistically significant differences exist among the impression materials; however, relative to the impression materials currently being used successfully, the combinations of irreversible hydrocolloid with silicone and modified reversible hydrocolloid with irreversible hydrocolloid were clinically acceptable.

Appleby DC, Smith W, Lontz JF, Mingledorff EB A study was conducted by combining two commercially available products of irreversible hydrocolloid with 4 products of reversible hydrocolloid in various combinations and the dimensional accuracy of these impression systems were compared. Also the bond strength between reversible and irreversible hydrocolloid systems were compared. It concluded that there was no statistically significant difference in dimensional stability among the eight combined impressions tested. They were sufficiently accurate for single unit restorations but multiple units remained questionable. There was statistically significant discrepancy in the bond strength among the 8 combined impression systems.4

Herring HW, Tames MA, Zardiackas LD An investigation was conducted to compare the difference in dimensional accuracy of a combined reversible- irreversible hydrocolloid impression system and the other commonly used impression systems. No statistically significant differences were found between the measurements of the various materials tested and those of the master model.3

Fusayama T, Kurosaki N, Node H, Nakamura M. They conducted a study to compare the dimensional accuracy of reversible and irreversible hydrocolloids individually and in combination with silicone elastomeric impression materials for indirect inlays. The combined reversible/irreversible hydrocolloid impression system provides no statistically significant difference with other impression system and eliminates the disadvantages of both the materials when used individually.

Skinner. EV, Hoblit NE. They demonstrated that the dimensional stability of reversible/irreversible hydrocolloid impression material was as accurate as other material used independently. The results showed that the technique employing an impression of both reversible and irreversible hydrocolloid materials in combination can be employed with an accuracy equal to that of the other techniques. OBJECTIVES OF THE STUDY To compare: 1. The dimensional accuracy of the combined reversible-irreversible hydrocolloids with the addition silicone impression material. 2. The bond strength of the various combinations of the agar alginate products.

7 MATERIALS AND METHODS SOURCE THE DATA-

A maxillary arch metal model with all the teeth present , 16 prepared for single unit restoration and 26 missing, 25 and 27 prepared to receive a 3 unit fixed partial denture on 25,26,27 will be used in the study.

METHOD OF COLLECTION OF DATA-

The commercially available agar syringeable products will be combined with the commercially available alginate products in various combinations.

To compare the dimensional accuracy: Agar syringeable product will be injected in the area of tooth preparation and alginate will be loaded on the tray and the impression will be made. Immediately, casts will be poured in improved stone. Then, following dimensions will be measured using a travelling microscope

1. The buccolingual diameter of the prepared teeth

2. The mesiodistal diameter of the prepared teeth

3. The height of the prepared teeth

4. The distance between 16 and 25, 16 and 27 measured from the center of these prepared teeth

Later the impressions of commercially available addition silicones will be made and casts will be poured with improved stone. The same dimensions will be measured.

Then these dimensions will be compared with that of the metal model. Then the discrepancy of each material from the standard dimensions of the metal model will be compared and statistically analyzed.

To compare the bond strength between the agar and alginate in combinations:

Special molds will be fabricated to test tensile bond strength between both the hydrocolloids. Perforations will be made in the molds for retention of the materials. Then the tensile bond strength between the agar and alginate will be determined in a standardized testing machine using the loading system. Alginate will be loaded in one half of the mold and agar in the other half. The excess will be leveled off. The bond strength will be calculated by the formula:

Bond strength= Load at failure. Bond area Then, these data will be statistically analyzed.

Does the study require any investigation or intervention to be conducted on patients or other humans or animals? If so please describe briefly.

Has ethical clearance have been obtained from your institution in case of 7.3?

7 9. Signature of The Candidate

10 Remarks of the Guide .

11 Name and Designation DR. ARVIND MOLDI, MDS . [In block letters] PROFESSOR, DEPARTMENT OF PROSTHODONTICS 11.1 Guide 11.2 Signature

11.3 Co-guide 11.4 Signature

12 12.1 Head Of The Department DR.SUDHINDRA MAHOORKAR, MDS PROFESSOR AND HEAD DEPARTMENT OF PROSTHODONTICS 12.2 Signature

13 13.1 Remarks of Chairman and Principal

13.2 Signature