<p> International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25</p><p>Original article: A Comparative evaluation of shear bond strengths of denture base to cross linked acrylic resin maxillary anterior teeth with and without retentive grooves - An in- vitro study Dr.D.Sudha Madhuri 1*, Dr.B.Sreeramulu2</p><p>1Associate Professor & Incharge, Dept.of Prosthodontics,Govt,Dental College & Hospital, Vijayawada Andhra Pradesh, India. 2Associate Professor & Incharge, Dept.of Prosthodontics,Govt,Dental College & Hospital, Afzalgunj, Hyderabad ,Telangana, India Corresponding author: Dr.B.Sreeramulu</p><p>Abstract: In our experimental study, the aim was to measure the shear bond strength exhibited by Denture base to cross linked acrylic resin maxillary anterior teeth with and without retentive grooves on their ridge lap surfaces and to compare the bond strengths of each maxillary anterior tooth type as the adequacy of shear bond strength of each Maxillary anterior resin teeth to the acrylic denture base is questionable. Success rate of approximately 90% was obtained with vertical retentive grooves on canines and central incisors. We believe that this method can be used to improve the bond strength of the teeth with the denture base material and prevent their dislodgement from the denture base1,2 Key words : Shear bond strength, cross-linked acrylic resin teeth ,retentive grooves. ------Introduction: base like faulty boil out procedures, residual wax During the past few decades, several scientific on ridge lap surfaces of teeth, careless application developments were carried in the fields of Dental of tin foil substitutes and other separating medium materials and Prosthodontics to produce denture like sodium alginate to teeth leading to base materials that exhibited excellent fit, contamination of their ridge lap surfaces. dimensional stability ,strength, tissue tolerance, The resistance to fracture of acrylic resin teeth from ease of fabrication ,esthetics and are economical. denture base depends on SHEAR BOND Though many types of denture base materials were STRENGTH which gives an indication of material developed, acrylic polymers remained as the most performance under conditions of static loading.3,4 commonly used ones since their introduction by Attempts to increase the strength of the bond Harold Veron in 1937.Ever since then, there has between acrylic resin teeth and heat cured denture been constant evolvement of the material to base resin include achieve best results.Acrylic resin teeth are 1. Grinding the glossy ridge lap surface of preferred as functional portions with acrylic resin resin teeth. denture base material as they became integral part 2. Painting the ridge lap surfaces of teeth of the denture by their chemical bonding resulting with monomer polymer solution. in an overall stronger one unit denture. 3. Cutting retentive groves in the ridge lap However there are several factors which resulted in surface of teeth. poor bonding of acrylic resin teeth to the denture Retentive grooves placed in the ridge laps of</p><p> www.ijhbr.com ISSN: 2319-7072 1 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25 denture teeth, increase the area available for removed by flushing away with hot boiling water. physical and chemical bonding and secure the teeth After the process of dewaxing, the specimens were to the base firmly.5,6 allowed to cool. At this stage plastic surfaces of Considering the developments in heat cure acrylic teeth were painted with one coat of separating denture base resins and improvements in cross- medium. Six acrylic mold specimens containing 10 linked acrylic resin material teeth, the hypothesis acrylic resin teeth each were then prepared by for this study were conventional curing method of which three 1.The shear bond strength of cross-linked acrylic specimens were cured with DPI brand resin resin teeth with grooves cut on their ridge-lap material and other three with TREVALON brand surface would be higher than those without resin material. grooves. The monomer to polymer ratio was maintained at 2.The shear bond strengths of all three types of 1:3 by volume for all the samples. A pipette was cross linked acrylic resin maxillary anterior used to transfer the required volume of monomer to teeth used in this study would be similar a clean, dry, air tight porcelain mixing jar. The Aims of this study were Thepolymer was measured with a measuring 1.To compare the shear bond strengths of denture cylinder and transferred to the jar containing base to acrylic resin teeth with and without monomer. Thorough mixing was done with a clean retentive grooves cut on their ridge lap surface. stainless steel spatula and the jar was closed till the 2. To determine whether central incisor or lateral mix reached dough stage. The resin was removed incisor or canine acrylic resin teeth used in this from mixing container and rolled into a rope like study, has higher bond strength to denture base. form and placed into upper half of the mold. The Materials and methods: flask was re-assembled and was bench pressed by The glossy ridge-lap surface of 90 cross-linked applying pressure incrementally. Pressure was acrylic resin maxillary anterior teeth of which, 30 applied until the major portions of the edges of the were central incisors,30 were lateral incisors and 30 flask closely approximate one another. The flask were canines.The specimens were divided into with acrylic resin was allowed to bench cure for three similar groups, 15min. Group A: No further tooth preparation was carried out. Group B:A mesio-distal groove 2mm deep and 2mm wide was cut into the ridge-lap surface of tooth. Group C:A vertical groove 2mm deep and 2mm wide was cut into the center of the ridge-lap surface of tooth extending half way up the lingual surface. Similar teeth were mounted in numbers of ten on triangular shaped wax molds to produce nine wax mold specimens and then flasked.The wax was</p><p> www.ijhbr.com ISSN: 2319-7072 2 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25</p><p>Acrylic Resin Teeth With Horizontal Groove,No Groove And Vertical Retentive Groove</p><p>Shear Bond Strength Testing: specimen in contact with it in the centre of support The specimens were subjected to testing on a pan or by measurement of the motion of loading universal testing machine INSTRON (model 6025). hose relative to the support. This test was The test was initiated by applying load to the conducted as per ASTM-D790. The site of specimen at a specified cross head speed of fracture of tooth from resin model was recorded 5mm/min at an angle of 130° to the long axis of as through the tooth, through acrylic resin and at the tooth until fracture occurred. The deflection the tooth acrylic interface of all the teeth fractured was measured either by the gauge under the at tooth acrylic interface.</p><p>Instron Universal Testing Machine</p><p> www.ijhbr.com ISSN: 2319-7072 3 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25</p><p>Instron Machine 3 Point Bend Test FORCE (Kg / cm2) REQUIRED TO SEPARATE CENTRAL INCISORS FROM CAST Name of the Group – Group – B Group Denture A Horizontal – C Base Resin No Groove Vertical Groove Groove 16 19 25 10 20 44 15 22 38 8 24 33 19 20 27 DPI 28 32 45 33 38 46 16 35 37 25 31 39 13 29 43 Group – Group – B Group – A C 22 39 46 26 29 38 18 19 42 27 30 53 23 48 45 TREVALON 20 52 51 33 32 36 40 40 44 42 35 52 39 24 47</p><p> www.ijhbr.com ISSN: 2319-7072 4 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25</p><p>Statistical analysis: minimum is 19kg/cm2. (Mean and SD 31.8889 ± The results were subjected to a statistical analysis 9.3676) using a one way analysis of variance (ANOVA) The maximum bond strength obtained among the and were appropriate. specimens of group C is 53kg/cm2 while the Results: mFORCE (Kg / cm2) REQUIRED TO SEPARATE Shear bond tests: CENTRAL INCISORS FROM CAST The results were given in table. Table II: Table I: The maximum bond strength obtained among the The maximum bond strength obtained among the specimens of group A for lateral specimens of group A for Central incisor teeth is 42 Incisor teeth is 24kg/cm while the minimum is kg/cm2 while the minimum is 8 kg/cm2. (Mean and 6kg/cm2. (Mean and SD 13.7059 ± 4.32123) SD 22.1765 ± 8.5676) The maximum bond strength obtained among the The maximum bond strength obtained among the specimens of group B is 32kg/cm2 while the specimens of group B is 52kg/cm2 while the</p><p> www.ijhbr.com ISSN: 2319-7072 5 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25 minimum is 9kg/cm2. (Mean and SD 17.0556 ± The maximum bond strength obtained among the 6.8382) specimens of group C is 55kg/cm2 (Mean and SD 29.5556 ± 11.6023)</p><p> www.ijhbr.com ISSN: 2319-7072 6 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25</p><p>FORCE (Kg / cm2) REQUIRED TO SEPARATE LATERAL INCISORS FROM CAST Name of the Group – Group – B Group – Denture A Horizontal C Base Resin No Groove Vertical Groove Groove 8 10 15 13 12 25 7 9 27 12 15 23 11 10 19 DPI 6 18 13 15 8 18 13 11 15 9 12 24 11 13 26 Group – Group – B Group – A C 23 24 34 15 23 29 13 32 33 16 24 42 TREVALO 14 16 37 N 17 24 28 16 21 31 21 23 53 23 14 55 24 28 46</p><p>Table III: The maximum bond strength obtained among the specimens of group A for Canine teeth is 51 kg/cm2</p><p> www.ijhbr.com ISSN: 2319-7072 7 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25 while the minimum is 13 kg/cm2. (Mean and SD while the minimum is 15kg/cm2. (Mean and SD 26.8824 ± 11.0277). 33.8333 ± 13.7595). The maximum bond strength obtained among the The maximum bond strength obtained among the specimens of group B for Canine teeth is 60kg/cm2 specimens of group C for Canine teeth is 118kg/cm2 while the minimum is 21 kg/cm2. </p><p>TABLE III FORCE (Kg / cm2) REQUIRED TO SEPARATE CANINE TEETH FROM CAST Name of Group – A Group – Group – the No Groove B C Denture Horizont Vertical Base Resin al Groove Groove 17 35 39 14 ** 26 ** 24 28 24 15 34 19 20 33 DPI 15 17 27 13 23 21 25 27 ** 20 26 42 18 19 56 Group – A Group – B Group – C 27 55 68 31 43 88 29 54 102 38 42 118 TREVALO 40 38 121 N 51 60 132 39 33 88 37 35 67 ** 41 96 ** Indicate the teeth fractured during deflasking Discussion: maxillary anterior resin teeth with and without Acrylic resin has become almost universal since its retentive grooves made on their ridge-lap surfaces. introduction in 1937 as a denture base material as This study also concentrated on the comparison well as the component of the resin cross-linked of shear bond strengths exhibited by cross linked teeth.7,8This study was conducted to compare the acrylic resin maxillary central incisors, lateral shear bond strengths exhibited by denture base to incisors and canines used in this study.</p><p> www.ijhbr.com ISSN: 2319-7072 8 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25</p><p>The results showed that the mean bond teeth from TREVALON than from DPI. Morrow et strength exhibited by those specimens without al., using a tensile force to separate teeth from retentive grooves was 21.231Kg/sqcm , for those denture base resin, found that bond strength of high with horizontal grooves was 27.503Kg/sqcm and impact resin to plastic teeth was significantly for those with vertical retentive grooves was greater than standard resin. In the present study, a 45.648Kg/sqcm .This indicated that specimens combined shear compressive force was applied at with vertical retentive grooves showed an angle of 130° to lingual surface of teeth to significantly higher bond strength than those with simulate clinical conditions. A statistically horizontal grooves and without grooves. The mean significant interaction was found between denture bond strengths obtained for central incisor was base resins and tooth type. TREVALON showed a 31.928Kg/sqcm, for lateral incisor was better bond strength with all the types of teeth and 20.164Kg/sqcm and for canine was it Acrylic resin has become almost universal since 42.990Kg/sqcm, the highest among the three tooth its introduction in 1937 as a denture base material types tested in this study.The Vertical retentive as well as the component of the resin cross-linked grooves showed a statistically significant superior teeth . This study was conducted to compare the retention in all tooth types. The vertical groove is shear bond strengths exhibited by two brands of closer to the point of application of force. A short conventional heat cure denture base resin lever arm requires greater force to separate the materials DPI and TREVALON to cross linked tooth from denture base.Canine teeth bonded more acrylic resin maxillary anterior teeth of securely to denture base resin than central incisors PREMADENT brand. This study also and lateral incisors. Thisfinding may be accounted concentrated on the comparison of shear bond for the ridgelap of canine presenting a greater strengths exhibited by cross linked acrylic resin surface area for bonding to acrylic resin. maxillary central incisors, lateral incisors and Morrow et.al using a tensile force to separate canines used in this study. teeth from denture base resin found that from The results showed that the mean bond strength denture base resin found that bond strength of high exhibited by DPI heat cure denture base material impact resin to plastic teeth was significantly was 22.580 kg/cm2 while the same for greater than standard resin.In the present study a TREVALON was 40.401 kg/cm2 which indicated combined shear compressive force was applied at that TREVALON has a better bond strength an angle of 130degrees to simulate clinical compared to DPI denture base material. The mean conditions. bond strength for each tooth type tested also Non significant stastical interactions was noted showed significant difference. The mean bond between tooth type and the retentive grooves .A strength obtained for central incisor was 31.928 significant statistical interaction was found between kg/cm2 , for lateral incisor was 20.164 kg./cm 2, tooth type and denture base resin. Canine teeth while that exhibited by canine tooth was 42.990 bonded more securely to denture base resin than kg./cm2, the highest bond strength among the three central and lateral incisors. This finding may be types of teeth tested in this study. accounted for the ridge lap of canine presenting a Conclusions: greater surface area for bonding to acrylic resin. A Within the limitations of the methodology of the significantly greater force was required to separate study, the main conclusions which can be drawn</p><p> www.ijhbr.com ISSN: 2319-7072 9 International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25 are as follows.  No consistent trend was noted in the site  A significantly greater force was required of fracture for teeth with horizontal and to separate teeth with retentive grooves vertical retentive grooves on application than without grooves from the denture of force, all the teeth without retentive base.. grooves fractured at the tooth acrylic resin  Canine tooth type with vertical retentive interface. grooves exhibited higher bond strength  An increase in the ridge lap surface area of when compared to other tooth types tested teeth resulted in an increase in shear bond in this study.. strength</p><p>References 1. CUNNINGHAM JL.Bond strength of denture teeth to acrylic bases. J Dent 1993; 21(5): 274-280. 2. Jakahashi Y, Chain J.Bond strength of denture teeth to denture base resins.International journal of prosthodontics. 2000;13(1): 59-65. 3. Thean HP, Chew CL, Goh KL.Shear bond strength of denture teeth to base, a comparative study. Quintenssence Int. 1996 ;27(6):425-428. 4. John N Anderson.The strength of the joint between plastic and copolymer acrylic teeth and denture base resins. British Dental Journal. 1958; 6: 319-320. 5. GeertsAVM.A comparison of the bond strength of the microwave and water bath cured denture material. JPD.1990;70:406-409. 6. Harrison WM, Stansburg BE. The effects of joint surface contour on the transversal strength of repaired acrylic resins. JPD.1970;23:464. 7. Consani S, Stolf WL, Ruhnke LA.Comparative study of bonding of acrylic teeth and resin bases. JPD. 1993;690. 8. Can G, KhasuG.An evaluation of the bond strength of plastic teeth to acrylic denture base material. Ankare Umin Ilekein Jak Derg. 1990;17(1): 97-101.</p><p> www.ijhbr.com ISSN: 2319-7072 10</p>