The Influence of Implant Abutment Surface Roughness and the Type of Cement on Retention of Implant Supported Crowns
S. Varalakshmi Reddy1, M. Sushender Reddy2, C. Rajaneesh Reddy3, Padmaja Pithani4, Santosh Kumar R5, Ganesh Kulkarni6
1 Professor & HOD, Department of Prosthodontics, MNR Dental College & Hospital, Sangareddy, Telangana, India.
2 Senior Lecturer, Department of Prosthodontics, SVS Institute of Dental Sciences, Mahabubnagar, Telangana, India.
3 Reader, Department of Oral Surgery, KLR Lenora College of Dental Sciences, Rajanagaram, Rajamundry, Andhra Pradesh, India.
4 Reader, Department of Prosthodontics, Sri Balaji Dental College, Moinabad,R.R Dist, Telangana, India.
5 Reader, Department of Prosthodontics, AME’S Dental College, Raichur, Karnataka, India.
6 Senior Lecturer, Department of Oral Pathology, Malla Reddy Institute of Dental Sciences, Suraram, Hyderabad, Telangana, India.
NAME, ADDRESS, E-MAIL ID OF THE CORRESPONDING AUTHOR: Dr. S. Varalakshmi Reddy, Professor & HOD, Department of Prosthodontics, MNR Dental College and Hospital, Fasalwadi, Sangareddy, Telangana State– 502294, India.
E-mail: vara_reddy@yahoo.co.in
Objectives: To provide relative data on the retentive characters of the commonly used cements on different implant abutment surfaces.
Materials and Methods: A total of 20 implant abutments were divided into 2 groups. Ten implants were unaltered and ten were air borne particle abraded with 50μ aluminium oxide. Three luting agents (Tempbond, IRM and ImProv) were used to divure the crowns to abutments. All the crowns were removed from the abutment with an Instron machine at 0.5mm per minute and tensile bond strengths were recorded. Statistical analysis was performed using Anova, Paired t-test and Post-Hoc tests.
Results: IRM showed the highest mean tensile strength among the three cements when used with treated and untreated implant abutment surfaces. Change in the abutment surface roughness had no effect on the mean tensile bond strength of TempBond and IRM cements, whereas ImProv cement showed reduced tensile strength with sandblasted surface.
Conclusion: When increased retention is required IRM cement with either sandblasted or milled surface could be used and when retrievability is required cements of choice could be either TempBond or ImProv.
Introduction
Implants have revolutionized the dental practice in the last few decades. They are being considered as a better alternative to conventional fixed or removable prosthesis as they have overcome many of the limitations encountered with these conventional approaches. Implant supported prostheses are considered as highly esthetic, functional restorations with long-term predictability [1]. One of the most important decisions in implant prosthodontics is to choose between screw-retained and cement retained restorations [2]. The choice between screw-retained and cement retained restorations has always been a controversy in the literature. It has been documented that screw retained restorations were successful in edentulous arches. However, they do have disadvantages such as, screw loosening and screw fracture [3]. Cement retained prostheses have superior esthetics, easier control of occlusion, and are economical when compared to screw retained restorations but are not retrievable [4].The abutment preparation design and the cementation technique are similar to the conventional fixed procedures for natural teeth. So, all the factors that influence the retention in the restorations over natural teeth also affect the retention in implant supported crowns [1]. The factors that can affect the retention are abutment taper, surface area, height, surface finish and roughness. By increasing the surface roughness of the implant abutment the retention of the cement retained restoration can be improved [4]. The type of cement used is also an important factor in determining the retention of the restoration [1]. Retention of the luted provisional implant restoration can be a challenge, especially as the provisional implant restoration should minimize micro movement that may interfere with implant osseointegration [5,6].
Improvement of the implant surfaces such as airborne-particle abrasion and acid etching make early or immediate loading more successful. The values for the retentive strength for the different classes of luting cements are reported in the literature [7–14]. The choice of cement for an implant supported restoration should be based on the need or desire for retrievability, the anticipated amount of retention needed, removal and cost [12–17].The aim of this study is to provide relative data on the retentive characters of the commonly used cements on different implant surfaces.
Materials and Methods
Impressions of the implant abutments were made and casts were poured [Table/Fig-1]. Wax patterns were fabricated by dipping technique (waxpot) to provide 0.5 mm thick standard wax patterns [17,18] and a sprue of uniform length of 3mm was attached to the wax pattern.
![](/articles/images/5621//jcdr-9-ZC05-g001.jpg)
Wax patterns were then invested in a phosphate bonded investment and casting was done using nickel chromium alloy. Burnout casting procedure was followed according to the manufacturer’s instructions and the castings were divested. The remnants of investment on the surface of the abutment were removed by the use of sandblaster with the use of 50 microns aluminium oxide. After sand blasting, the samples were ultrasonically cleaned for 3 min in a distilled waterbath.
Finally 60 specimens were divided into 2 groups of 30 each. Each group was sub divided into 3 subgroups of 10 samples each.
Group I: Control group.
Group II: Sandblasting group
An abrasive tool with 50 micron aluminium oxide particles with a pressure of 5 kg/cm2 at a distance of 5 mm away from the surface with a circulating motion at 6 mm in diameter for 20 seconds was used to abrade the abutment surface. After sandblasting, the specimens were ultrasonically cleaned for 15 mins in distilled water.
Autopolymerising acrylic resin blocks were fabricated, allowing the implant analogs to be placed in the blocks perpendicular to the face of the resin block. The abutments were connected to the implant analogs and torqued to 35 N-cm. After fabrication of 3 cast crowns for each abutment the luting agent Tempbond, ImProv and IRM cements were used to secure the crowns to respective abutments [Table/Fig-2]. All specimens were stored in 100% humidity for one day at 37oC prior to testing. Each crown was removed from the abutment with an Instron mechanical testing machine at 0.5mm/min [19] and the tensile strength was recorded.
Cements used in the study
![](/articles/images/5621//jcdr-9-ZC05-g002.jpg)
Results
When Group I (control) specimens were luted with type A (IRM), typeB (TempBond cement) and type C (ImProv cement), the mean tensile bond strengths were 258.28N, 138.41N and 184.86N respectively.When Group II (sandblasted) specimens were luted with type A (IRM), type B (TempBond cement) and type C (ImProv cement), the mean tensile bond strengths were 260.68N, 138.28N and 152.13N respectively [Table/Fig-3,4,5]. Both type A and B did not show any significant differences in tensile strength between the control and sandblasted surfaces whereas type C showed an increase in the tensile bond strength with the Group I samples (control) when compared to Group II samples.
Mean tensile bond strength of Type A cement with Group I and II-Paired Samples Statistics
| N | Mean | Std. Deviation | Std. Error Mean |
---|
Control Irm | 10 | 258.280 | 39.6837 | 12.5491 |
Sandblasted Irm | 10 | 260.680 | 42.8893 | 13.5628 |
Mean tensile bond strength of Type B cement with Group I and II-Paired Samples Statistics
| N | Mean | Std. Deviation | Std. Error Mean |
---|
Control Temp Bond | 10 | 138.410 | 11.6730 | 3.6913 |
Sandblasted Temp Bond | 10 | 138.280 | 12.4334 | 3.9318 |
Mean tensile bond strength of Type C cement with Group I and II-Paired Samples Statistics
| N | Mean | Std. Deviation | Std. Error Mean |
---|
Control Improv | 10 | 184.860 | 52.0776 | 16.4684 |
Sandblasted Improv | 10 | 152.130 | 45.7934 | 14.4811 |
Statistical Analysis
Paired t-test was used to compare the mean tensile bond strength values between the three luting agents among the two groups. The mean tensile strength values of Group I and Group II did not show any statistically significant differences when tested with type A and type B cements(p>0.5). However, there was a decrease in the mean tensile bond strength value with Type C cement in the sandblasted group by 17%, which was statistically significant (p<0.5).
Discussion
Since the surface condition of the abutment and the type of the provisional luting agents are the factors that can be controlled by the clinician, modifications of the surface of the solid abutment and the different provisional luting agents were used to evaluate retention. Surface roughness increases the retention due to resulting micro retentive ridge and groove patterns. Increase in retention resists, or opposes the movement of the abutment under occlusal loads and prevents removal of the restoration by the forces applied in an apical or oblique direction. If the cement is more retentive the clinical retrievability without damage to the restorations, implant or peri implant tissue may be difficult [20].
In sub-group A the mean value of the tensile strength of the Group I (control) was 258.20N and in Group II (sandblasted group) was around 260.68N. The difference between the values of the mean tensile strength was not statistically significant (p-value >0.5). In sub-group B also the mean tensile strength of group I (control) was 138.41N and Group II (sandblasted) was 138.20N. The differences between the mean tensile strength were also not statistically significant (p-value>0.5). Few other studies indicate that the effect of interaction between the surface characteristics and luting agent affect the tensile bond strength. This surface alteration could be done either with the use of rotary instruments or sand blasting. In a study done by Yongsik Kim [21], there were no differences in the tensile strength of TempBond and other provisional luting agents when used with all different surface conditions. In another study done by Wolfart M [22] retention of the castings cemented with eugenol free zinc oxide cements was not affected by abutment surface conditioning by air abrasion. According to DJ Witwer [23], rough finished surfaces showed a significantly (p<.05) greater retention than the smooth finished surfaces with grooved crowns. According to Niwat Juntavee [24], the retention values of cements increased with increasing surface roughness of the restorations or abutments. However, the present study indicated that the higher surface roughness did not influence the retention values of eugenol free zinc oxide or TempBond cements. This could be due to the limitive cohesive strength of the cement [25]. Hence, when Type A or Type B cements are used as luting agents, surface treatment either with rotary instruments or air abrasion would be equally effective in increasing the retention.
In sub-group C the mean tensile strength values of Group I samples were 184.86N, while that of Group II samples were 152.13N. From the values it is evident that the tensile strength of abutments which were sandblasted were less than that of the control group which were also statistically significant (p-value<0.5). According to another study by Shane N White [26] several factors influence the film thickness of the luting material. These include the substrate the material is tested against, the size or shape of filler particles, the viscosity of the unset materials, and its rate of set. According to another study by Mona Wolfart [22] air abrasion of the castings and abutments may have also decreased the inner fit of the castings, which may have caused different film thickness leading to differences in tensile bond strength. In another study by Y Taira et al., minimal decrease in the bond strength was obtained with alumina blasting [27].
The maximum retention force required to retrieve a cemented restoration without damage to the adjacent structures, is not known. As there are no criteria for minimum amount of force required to prevent easy dislodgement of crowns, the choice of cements and abutment surface modifications is based on the clinician’s choice [4].
Conclusion
The results of this study showed that Type A (IRM) cement exhibited the highest tensile strength among the cements tested, followed by type C (ImProv) and type B cement (TempBond). Both Type A and Type B cements did not exhibit any significant differences in the tensile bond strength among the control (milled) and sandblasted group. Type C (ImProv) exhibited statistically significant increase in the tensile bond strength values with Group I (Control) when compared to Group II (Sand blasted). By evaluating the above results it can be suggested that when increased retention is required (260N) Type A (IRM) cement with either sandblasted or milled surface could be used and when retrievability is considered, cements of choice could be either Type B (TempBond) or Type C (ImProv).
[1]. Modi R, Mittal R, Kohli S, Singh A, Sefa I, Screw versus Cement Retained Prosthesis: A Review Int J Adv Health Sci 2014 1(6):26-32. [Google Scholar]
[2]. Wittneben JG, Millen C, Bragger U, Clinical performance of screw versus cement retained fixed implant supported reconstructions. A systematic review Quintessence Int 2014 29:84-98. [Google Scholar]
[3]. Jugdev J, Farahani AB, Lynch E, The effect of air abrasion of metal implant abutments on the tensile bond strength of three luting agents used to cement implant superstructures: An in vitro study Quintessence Int 2014 29(4):784-90. [Google Scholar]
[4]. Sahu N, Lakshmi N, Azhagarasan NS, Agnihotri Y, Rajan M, Hariharan R, Comparison of the effect of implant abutment surface modifications on retention of implant supported restoration with a polymer based cement J Clin Diagn Res 2014 8(1):239-42. [Google Scholar]
[5]. Randi AP, Hsu AT, Verga A, Verga J, Dimensional accuracy and retentive strength of a retrievable cement-retained implant-supported prosthesis Int J Oral Maxillofac Implants 2001 16:547-56. [Google Scholar]
[6]. Squier RS, Agar JR, Duncan JP, Taylor TD, Retentiveness of dental cements used with metallic implant components Int J Oral Maxillofac Implants 2001 16:793-98. [Google Scholar]
[7]. Bresciano M, Schierano G, Manzella C, Screti A, Bignardi C, and Preti, G. Retention of luting agents on implant abutments of different height and taper Clin Oral Implants Res 2005 16:594-98. [Google Scholar]
[8]. Gorodovsky S, Zidan O, Retentive strength, disintegration, and marginal quality of luting cements J Prosthet Dent 1992 68:269-74. [Google Scholar]
[9]. Diaz-Arnold AM, Vargas MA, Haselton DR, Current status of luting agents for fixed prosthodontics J Prosthet Dent 1998 81:135-41. [Google Scholar]
[10]. Mansour A, Ercoli C, Graser G, Tallents R, Moss M, Comparative evaluation of casting retention using the ITI solid abutments with six cements Clin. Oral. Impl. Res 2002 13:343-48. [Google Scholar]
[11]. Montenegro AC, Machado AN, Gouvea CVD, Tensile strength of cementing agents on the ceraone system of dental prosthesis on implants Implant Dent 2008 17(4):451-60. [Google Scholar]
[12]. Sheets JL, Wilcox C, Wilwerding T, Cement selection for cement retained crown technique with dental implants J Prosthodont 2008 17:92-96. [Google Scholar]
[13]. Maeyama H, Sawase T, Jimbo R, Kamada K, Suketa N, Fukui J, Retentive strength of metal copings on prefabricated abutments with five different cements Clin Implant Dent Relat Res 2005 7(4):229-34. [Google Scholar]
[14]. Li ZC, White SN, Mechanical properties of dental luting cements J Prosthet Dent 1999 81:597-609. [Google Scholar]
[15]. Lawson NC, Burgess JO, Mercante D, Crown retention and flexural strength of eight provisional cements J Prosthet Dent 2007 98:455-60. [Google Scholar]
[16]. Lee SY, Wang CC, Chen DC, Lai YL, Retentive and compressive strengths of modified zinc oxide-eugenol cements Journal of Dentistry 2000 28:69-75. [Google Scholar]
[17]. Valderrama S, Roekel NV, Andersson M, Goodacre CJ, Munoz CA, A comparison of the marginal and internal adaptation of titanium and gold-platinum-palladium metal ceramic crowns Int J Prosthodont 1995 8:29-37. [Google Scholar]
[18]. Oruc S, Tulunoglu Y, Fit of titanium and a base metal alloy metal-ceramic crown J Prosthet Dent 2000 83:314-18. [Google Scholar]
[19]. Lepe X, Bales DJ, Johnson GH, Retention of provisional crowns fabricated from two materials with use of four temporary cements J Prosthet Dent 1999 81:469-75. [Google Scholar]
[20]. Carl E, Misch. Dental Implant Prosthetics 2005 St. LouisMosby Year Book [Google Scholar]
[21]. Kim Y, Yamashita J, Shotwell JL, Chong KH, Wang HL, The comparison of provisional luting agents and abutment surface roughness on the retention of provisional implant-supported crowns J Prosthet Dent 2006 95:450-55. [Google Scholar]
[22]. Wolfart M, Wolfart S, Kern M, Retention forces and seating discrepancies of implant retained castings after cementation Int J Oral Maxillofac Impl 2006 21:519-25. [Google Scholar]
[23]. Witwer DJ, Storey RJ, Von Fraunhofer JA, The effects of surface texture and grooving on the retention of cast crowns J Prosthet Dent 1986 56(4):421-24. [Google Scholar]
[24]. Juntavee N, Millstein PL, Effect of surface roughness and cement space on crown retention J Prosthet Dent 1992 68(3):482-86. [Google Scholar]
[25]. Craig RG, Restorative Dental Materials 1993 St.LouisMosby Year Book [Google Scholar]
[26]. White SN, Yu Z, Film thickness of new adhesive luting agents J Prosthet Dent 1992 67(6):782-85. [Google Scholar]
[27]. Taira Y, Matsumura H, Yoshida K, Tanaka T, Atsuta M, Influence of surface oxidation of titanium on adhesion Journal of Dentistry 1998 26:69-73. [Google Scholar]