|Year : 2015 | Volume
| Issue : 1 | Page : 3-5
A study to evaluate the effect of taper on retention of straight and angled implant abutment
Roseline Meshramkar, Aishwarya Nayak, Abhishek Kavlekar, Ramesh K Nadiger, K Lekha
Department of Prosthodontic, SDM College of Dental Sciences and Hospital, Dharwad; RGUHS University, Bengaluru, Karnataka, India
|Date of Web Publication||2-Apr-2015|
Department of Prosthodontics, SDM College of Dental Sciences and Hospital, Dharwad - 580 009, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aim: The purpose of this study was to evaluate the effect of taper on retention of copings in straight and angled implant abutment.
Materials and Methods: Totally, 10 straight abutments (Adin Israel) of 3° taper and angled abutment of 15° taper with their analogs were used. Twenty castings were fabricated on the abutment that incorporated an attachment to allow removal. Castings were cemented to abutments with provicol (VOCO Germany). A uniaxial tensile force was applied to the crown using an instron machine until cement failure occurred.
Results: Data were subjected to Shapiro-Wilk test, and it was found that variables have a normal distribution. Hence, Student's t-test was performed, and P value was found to be 0.00 <0.05. Hence to infer significant statistical difference.
Conclusion: The retention of straight abutments was significantly more when compared to angled abutment when cemented with provicol. When using angled abutment, permanent luting agent should be the choice for cementation.
Keywords: Abutment, angled abutment, implant, luting agent, straight abutment, temporary luting agent
|How to cite this article:|
Meshramkar R, Nayak A, Kavlekar A, Nadiger RK, Lekha K. A study to evaluate the effect of taper on retention of straight and angled implant abutment. J Dent Implant 2015;5:3-5
|How to cite this URL:|
Meshramkar R, Nayak A, Kavlekar A, Nadiger RK, Lekha K. A study to evaluate the effect of taper on retention of straight and angled implant abutment. J Dent Implant [serial online] 2015 [cited 2019 Jun 26];5:3-5. Available from: http://www.jdionline.org/text.asp?2015/5/1/3/154414
| Introduction|| |
The use of dental implants in the rehabilitation of partially edentulous patients has become a well-established and accepted contemporary clinical method with predictable long-term success. , Ideally, implants should be placed parallel to each other and to adjacent teeth and be aligned vertically with axial forces. However, achieving this may not be possible owing to deficiencies in the ridge's anatomy. When dental implants are not placed parallel to adjacent teeth or contiguous implants, the clinician can use angled abutments to achieve proper restorative contours.  Factors such as the height and width of the prosthetic component, the type of cement and the cementing may the influence tensile strength of cemented prosthetic restoration. , Many of the present-day implant systems have abutments onto which superstructures can be cemented. This design permits the development of the desired occlusal inter digitation, improved esthetics, and correct loading characteristics. Abutment preparation designs and cementation techniques now mimic conventional fixed prosthodontic procedures for natural teeth.  Most manufacturers machine their abutments to a standard that approximates a 6° taper. The conclusion drawn is that machined abutments in implant dentistry (6° of taper) provide ideal retention that is 3-4 times the retention achieved on natural tooth preparation.  Numerous types of prefabricated abutments are available at specific angles. Preangled abutments with angulations varying from 15° to 35° often are commercially available. A 15° angulation of a prefabricated abutment can create parallelism between adjacent abutments.  The success of cement-retained designs depends largely on adequate retention and resistance.  Factors affecting implant supported restorations are similar to those affecting the luting of crown to natural teeth and taper height width of the abutment and type of luting agent. Straight implant abutment and angled implant abutment retention can be varied and be affected by type of the cement, taper, surface area, texture. The purpose of the study was to evaluate the retention of coping in straight and angled implant abutment.
| Materials and methods|| |
This study was conducted to evaluate the effect of taper on the retention of straight and angled implant abutments. A 10 Adin straight and 10 angled implant abutments were used in the study. The abutments were attached to implant analogs and vertically mounted in acrylic resin (self-cure acrylic resin DPI India) so as to apply tensile force to the long axis of the abutment. The abutments were connected to implant analogs. The 2 layers of die spacer were applied directly on the abutments 0.5 mm away from the margin. A wax coping with 1.5 mm for each sample were fabricated with direct wax up technique, a loop was waxed onto the upper surface of coping so as to facilitate the device of instron machine. The 20 wax patterns were invested and casted using Nicr Me alloy according to manufacturers' instructions. The copings were standardized and after casting it was removed trimmed cleaned. Visual inspection was done with magnification lens to assess the marginal integrity. All the copings were evaluated for adaptation and for accuracy of the fit on the abutment. The coping were accepted when they were seated completely with no gap along the margins. Ten copings for straight abutments and ten copings for angled abutments were cemented by provicol (VOCO, Germany). Provicol was used accordingly to manufacturer instructions. The copings were filled with cement, and it was seated with finger pressure and 10 kg load was applied for 5 min. A universal testing machine instron was used to measure the force required to dislodge the copings from the abutment with a cross head speed of 5 mm/min until cement failure occurred. Difference in mean tensile strength was analyzed by Shapiro-Wilk test.
| Results|| |
Data were subjected to Shapiro-Wilk test, and it was found that variables have a normal distribution. Hence, Student's t-test was performed. The mean force required for tensile failure of straight abutments in Newton was 54.9 (4.14 standard deviation [SD]) and that for angled abutment was 39.0 (4.10 SD). P value was found to be 0.00 < 0.05. Hence to infer significant statistical difference.
| Discussion|| |
The use of angled abutments facilitates paralleling nonaligned implants thereby making prosthesis fabrication easier. To achieve prosthetically desired parallelism between implant and teeth, the clinician can place an angled abutment, numerous types of prefabricated abutments are available at specific angle, preangled abutments with angulation varying from 15° to 35° often commercially available.  Neves et al., in 2013  demonstrated that the surface area, the angulation of the axial walls and the characteristics of cements influence the strength of metal crown cemented on customizable abutment. Breeding et al. 1992 suggested implant supported prosthesis cemented with the provisional cements are retrievable, and it is the cement chosen that is the controlling factor in the retention attained.  The proper handling of cement-retained implant prosthesis provides for retrievability without compromising the occlusion, esthetics, and stress distribution to the prosthetic components and bone implant interface.  Data from this study and a study by Neves et al. provides information regarding the effect of taper on the retention of the restoration. In our study, it was found that straight abutment had more retention compared to angled abutment, which was similar to Neves et al.  This shows that surface area and taper of the straight abutments are significant for the retention. , In our study, provicol was used for cementing for both the straight and angled abutments. When selecting a luting agent, it is important that the cement be easy to manipulate and remove without damaging implant components or surrounding soft tissues.  Hence, in our study, provical was used since it is easy to manipulate and remove; in a study done by Hebbel and Gajjar, it was found that improve showed greater resistance to dislodgement than the permanent zinc phosphate cement. Michalakis et al., found that nongenol may be more appropriate for cementation of implant supported FPDs when retrievability is important. Based on our findings, we can say when clinician uses angled abutment for fixed restoration, it is better to choose zinc phosphate cement or permanent luting agent than provisional luting agent. It is essential however that further studies has to be conducted with different angled abutments using different luting agents and its effect on the retention. Within the limitations of the study, it can be concluded that straight abutments had more bond strength compared to angled abutment. With straight abutments, provical can be used as luting agent and for angled abutment permanent luting cement should be selected.
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