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Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 12  |  Issue : 1  |  Page : 45-53

Effect of multiple reuse of commonly used implant analogs on the dimensional accuracy and the marginal gap between analog and abutment – An in vitro study


1 Department of Prosthodontics and Crown and Bridge and Implantology, GITAM Dental College, Visakhapatnam, Andhra Pradesh, India
2 Department of Prosthodontist, Confident Dental Labs, Bengaluru, Karnataka, India

Date of Submission16-Dec-2021
Date of Decision21-Jan-2022
Date of Acceptance27-Feb-2022
Date of Web Publication16-Jun-2022

Correspondence Address:
Dr. Ravi Shankar Yalavarthy
Department of Prosthodontics, GITAM Dental College and Hospital, Visakhapatnam, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdi.jdi_34_21

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   Abstract 

Statement of Problem: During the impression procedure, the implant's exact position in the oral cavity is transferred into the cast using impression post and implant analog. As the implant, analog is a lab component, it can be reused multiple times. Reuse of implant analogs may be desirable for both environmental and financial aspects. When implant analogs are reused, it is important to be assured that they are as accurate as new ones. Reusing of implant analog results in loss of precision which is the major key factor in the failure of implant prosthesis.
Purpose of the Study: The purpose of the present in vitro study is to assess the effect of multiple reuse of implant analogs of three different materials (SS, Ti, Al) on the dimensional accuracy (external and internal diameter) of implant analogs and the marginal gap between analog and abutment by using two die materials at different time intervals (0, 3rd, 6th, 9th, and 12th).
Materials and Methods: Three commonly used implant analog materials (stainless steel, titanium, and aluminum) and two type – IV die stone materials (Kalrock and Zhermack elite) are used to make the samples. A total of sixty implant analogs (20 each), sixty corresponding abutments (20 each) and 720 screws (240 each) were taken, which includes stainless steel, titanium, and aluminum manufactured by Adin, Genesis, and Equinox/Myriad plus, respectively. Addition silicone (light body consistency) was used to make an impression for the internal thread of implant analogues. The obtained samples are tested for external diameter and internal diameter of implant analogues, the marginal gap between analogue and abutment while reusing the implant analogues at the interval of times (0, 3rd, 6th, 9th, and 12th) using a stereomicroscope at ×50. Here the measured values at “0” interval were considered as the control group. The values obtained were statistically analyzed using the one-way ANOVA, independent t-test, and dependent t-test for multiple comparisons.
Results: Based on the results obtained, there was no change in the external diameter of three materials of implant analog in both die materials. There was an increase in the internal diameter of implant analogs in which the aluminum material exhibits more increase from 0 to 12th interval, and there was an increase discrepancy in the marginal gap between implant analog and abutment in which the aluminum material has more increase from 0 to 12th interval followed by the stainless steel and titanium implant analogs in both die materials. In between the two die materials, no significant difference was observed in all three parameters.
Conclusion: From the study, the following inferences are drawn: that titanium implant analogs can be used more than three times but not more than six times, stainless steel implant analogs can be used for not more than three times, and the aluminum implant analogs can be used for one time only. Hence, among the three materials, titanium implant analogs were most efficient for reuse.
Clinical implications: Micromovements of the abutment screw due to discrepancy or loss of surface details of threads of implant analog leads to micro-leakage and bacterial infiltration due to marginal gap discrepancy which further causes increased inflammation at the connection level contributing to a marginal bone loss that may affect the long-term success of implant prosthesis/implant.

Keywords: Abutment, aluminum, external diameter, implant analog, internal diameter, internal threads, marginal gap, reuse, stainless steel, titanium


How to cite this article:
Yalavarthy RS, Alla JN, Kalluri S, Mahadevan SS, Krishna M H, Kumar P S. Effect of multiple reuse of commonly used implant analogs on the dimensional accuracy and the marginal gap between analog and abutment – An in vitro study. J Dent Implant 2022;12:45-53

How to cite this URL:
Yalavarthy RS, Alla JN, Kalluri S, Mahadevan SS, Krishna M H, Kumar P S. Effect of multiple reuse of commonly used implant analogs on the dimensional accuracy and the marginal gap between analog and abutment – An in vitro study. J Dent Implant [serial online] 2022 [cited 2022 Jul 7];12:45-53. Available from: https://www.jdionline.org/text.asp?2022/12/1/45/347669


   Introduction Top


Dentists are striving to achieve optimum treatment outcomes. Patients are expecting optimum functionality following the replacement of lost teeth. Dentists successfully achieve the optimum treatment outcome employing various treatment protocols, including conventional removable prostheses, overdentures, and fixed prostheses, from the feedback provided by the patient's regarding the functionality and also the perception pertaining to the treatment rendered. This kind of relationship has helped both the clinicians and patients in their attempts to achieve the best form of prosthetic outcomes.[1]

There were many more treatment procedures in dentistry today, but dental implants involve scientific discovery, research, understanding, and application in clinical practice. Dental implants are considered as the most significant dental innovation of the present generation….!! A dental implant is a replacement for the root (or) roots of a tooth. Basically, an implant unit is consists of an implant fixture inserted into the prepared bone socket, an abutment screwed to the implant, and the prosthetics placed over the abutment. Now, there are several prosthetic implant–abutment choices, among which the dentist is supposed to choose the most predictable and reliable one.[2] An implant is placed into the bone of the person's jaw in various methods and using a variety of systems.

The most crucial step in a crown restoration procedure is producing an accurate mold/impression of the section requiring restoration and delivering it to the laboratory. It is possible to continue to the next step of the procedure once the area where the implant was inserted had sufficient time to heal. A mold/impression that was taken will then be sent to the laboratory for further processing. Analogs assist to transfer the implant in the patient's mouth by taking a mold with the help of impression post. Once the mold was taken, the lab implant analogs were screwed into a position which helps to create a final accurate mold for fabricating the final product.[3]

The implant analog's vital role is to grant an exact point of reference for the lab technician to place and shape the abutments to fabricate a crown or bridge for the implant. This step in the process must be done perfectly and with precision so that the mold was then sent to the lab will ensure a satisfactory outcome and naturally will affect the rest of the patient's treatment. It was imperative to choose high-quality implant analogs since the analog design was specifically made to replicate the quality of the final implant (both internal surface and external surface) and the positioning in the patient's mouth.[3]

The fabrication of implant components and the effects of clinical and laboratory phases can contribute to the misfit between implant and prosthesis. Two possible complications emerge from this misfit scenario: (1) Biological - increase of the load transfer to the bone and presence of mucosal inflammation due to the development of microflora in the micro-gap between the implant and the abutment with subsequent bone loss and (2) prosthetic - loosening/fracture of implant and prosthesis.[4]

In case of misfit between implant and abutment as well as between abutment and prosthesis, compressive and traction loads could be directed to the restoration, resulting in fracture of the restoration, loosening of the prosthesis and abutment screws, bone microfractures surrounding the implants, and even fracture of the implant body.[4] It was a fact that dental implant therapy is an expensive treatment modality. It has been stated that a fixed prosthesis supported by implants is more expensive than a conventional prosthesis. The high cost of dental implant components has always been a major concern.

Reuse of implant components may be desirable for both economic and environmental reasons. Metal implant components may be more suitable for reuse because they can be easily resterilized. Implant analogs were one of the metal implant components that were appealing to clinicians for reuse.[5] When implant analogs were reused, it is important to be assured that they were as accurate as new ones. Moreover, the number of times that the components can be reused safely and effectively should be determined. It is financially reasonable to reuse the implant analog if the accuracy is not compromised.

The purpose of the present in vitro study is to assess the effect of multiple reuse of implant analogs of three different materials (stainless steel, titanium, and aluminum) on the dimensional accuracy and the marginal gap between analog and abutment by using two die materials.


   Materials and Methods Top


A total of sixty implant analogs, sixty corresponding abutments and 720 screws were taken, which includes 20 each stainless steel (Adin Dental Implants, Israel), aluminum (Equinox/myriad plus Dental implants, Israel), and titanium (Genesis/Aktiv Dental implants, Kerala) manufactured implant analogs by different companies. Two different companies (Kalabhai, India and Zhermack, Italy) of die stone materials were used to mount the implant analogs. All these materials were procured through the open market [Flow Chart 1].



A custom-made die stone cuboid block of dimensions 27 mm × 27 mm × 18 mm was prepared and a perforated plastic receptacle of dimensions 40 mm × 50 mm × 40 mm was taken. By using these custom made die stone block and a perforated plastic receptacle a mold space was made using putty and light body consistency addition silicone materials. The time intervals included in the study were 0, 3rd, 6th, 9th, and 12th. In these intervals, the “0” time interval values were considered as control group values.

An square shaped acrylic die with A, B, C, D markings acts as a keyhole into which the implant analog was placed and the markings were transferred onto the implant analog. At 0 interval, the implant analogs were evaluated to measure inner and outer diameter by using the stereomicroscope. The implant analog was placed in the acrylic die and the markings were transferred on to the implant analog and from this, the outer diameter of implant analog was measured at the point A to C or B to D [Figure 1] and the inner diameter was evaluated by measuring the distance between A to C or B to D [Figure 2]. This was tested by using the stereomicroscope at ×50 magnification by an image processing software. After that, the implant analog and abutment was screwed by using hex driver and torque wrench with the recommended torque of 30Ncm. The assembled unit was used to measure the marginal gap values between the implant analog and abutment (assembled unit). For this also, the acrylic die was used in which the assembled unit was placed as a key in a keyhole for denoting the A, B, C, and D. The marginal gap values were measured at the four points (A, B, C, and D). Taking the average of these repeatable measuring points gives the value of the marginal gap values between the assembled units [Figure 3]. This was tested by using the stereomicroscope at ×50 by an image processing software. The values were tabulated and were further evaluated. These values were taken as a control group.
Figure 1: Measuring the implant analog external diameter

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Figure 2: Measuring the implant analog internal diameter

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Figure 3: Measuring the marginal gap between implant analog and abutment

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After “0” interval, the putty index with mold space obtained was used to fill with die stone material into which the implant analog was inserted by using a dental surveyor. This was done to position the implant analog at the center of the mold space filled with die stone. This procedure to be done for all three materials (stainless steel, titanium, and aluminum) of implant analog and then obtained samples (die stone block with implant analogue) were left untouched for 24 h. Then each sample was taken and corresponding abutment was connected to implant analog by hand torquing the abutment screw with the hex driver and torque wrench of about 30 Ncm. In each sample, the abutment screw was tightened and loosened about four times as the laboratory personnel approximately tightens and loosens the screw for four times during the fabrication of prosthesis. After every interval, the screw was discarded, and the new screw was taken for tightening the abutment to the implant analog. After that, the implant analog was retrieved from the die stone block by breaking the block mechanically with a chisel and hammer. Placing the chisel at the side adjacent to the implant analog placed in the die stone block without touching it and then hammering over the chisel mechanically makes the block break and retrieves the implant analogue. This was done for every sample, and the implant analogs were retrieved. Now the first interval was completed. The same procedure was done for the 2nd and 3rd intervals. After 3rd interval, the retrieved implant analogs were used for evaluating the external and internal diameter. The marginal gap values between the analogue and abutment were evaluated the same as the samples tested at 0 interval by using the stereomicroscope at ×50 magnification by an image processing software. The values were tabulated and were further evaluated. This is the same procedure done at the every three intervals and the samples were measured and the values were tabulated and were compared with the control group at 6th, 9th and 12th time. After the fabrication of samples, relevant testing and recording of data were performed, followed by appropriate statistical analysis was done using the SPSS software (IBM Company Integral Solutions Ltd, SurveyCraft Pty Ltd City, State, Country Chicago, Illinois, United States).


   Results Top


There is no change in the external diameter values at different time intervals of three different materials i.e., At “0” interval, the mean external diameter for SS, Ti, and Al for both groups were 3.92 mm, 3.89 mm, and 3.41 mm, respectively. At the “12th” interval, the mean external diameter for SS, Ti, and Al for both groups was same as at “0” interval. This infers that there is no change in the external diameter of the implant analog while reusing [Table 1].
Table 1: Comparison of two die materials (Group A and Group B) with mean external diameter values at different time intervals (0, 3rd, 6th, 9th, and 12th) in three different implant analogue materials (stainless steel, titanium, aluminium) by independent t-test

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For stainless steel implant analogs of both Group A and Group B from “0” interval to “3rd” interval, there is no change in the mean internal diameter value, i.e., 2.93 mm. For further intervals, there was an increase in the mean internal diameter when compared with “0” interval, i.e., for 6th interval the value was 2.95 mm, for 9th interval, the value was 2.96 mm and for 12th interval the value was 3.00 mm for both groups. This shows that there was a slight increase in the internal diameter while reusing. For titanium implant analogs of both Group A and Group B from “0” to “3rd” interval, “0” to “6th” interval and “0” to “9th” interval there is no change in the mean internal diameter value i.e., 2.96 mm. But for comparing from “0” to “12th” intervals there was a slight increase in the mean internal diameter value was 3.00 mm and 3.01 mm for Group A and Group B respectively. This shows that there was a slight increase in the internal diameter while reusing. For Aluminium implant analogues of both Group A and Group B from “0” interval to “3rd” interval there is no change in the mean internal diameter value i.e., 2.70 mm. For further intervals there was an increase in the mean internal diameter when compared with “0” interval i.e., for 6th interval the value was 2.74 mm, for 9th interval the value was 2.83 mm and for 12th interval the value was 2.86 mm for both groups. This shows that there was a slight increase in the internal diameter while reusing [Table 2].
Table 2: Comparison of three different implant analogue materials (stainless steel, titanium, aluminum) in two die materials (Group A and Group B) with mean internal diameter at different intervals (0, 3rd, 6th, 9th and 12th) by one way ANOVA

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The order of mean difference of mean internal diameter of implant analogues from “0” interval to “12th” interval of three different materials (Stainless steel, Titanium, Aluminium) were:

Aluminium (0.16 mm) > Stainless steel (0.07 mm) > Titanium (0.04 mm).

For the SS at “0” interval has mean marginal gap value of 0.87 μm and 0.85 μm of Group A and Group B respectively. For further intervals there was an increase in the mean marginal gap values i.e., at 12th interval it has mean marginal gap value of 1.78 μm and 1.79 μm of Group A and Group B respectively which shows the values doubled (approx.) when compared with “0” interval. For Titanium at '0' interval has mean marginal gap value of 0.71 μm and 0.69 μm of Group A and Group B. For further intervals there were an increase in the mean marginal gap values i.e., at 12th interval it has mean marginal gap value of 1.32 μm and 1.33 μm of Group A and Group B which shows the values nearly doubles when compared with “0” interval. For Aluminium at “0” interval has mean marginal gap value of 0.86 μm and 0.87 μm of Group A and Group B. For further intervals there were an increase in the mean marginal gap values i.e., at 12th interval it has mean marginal gap value of 2.33 μm and 2.32 μm of Group A and Group B which shows the values nearly triples when compared with “0” interval [Table 3].
Table 3: Comparison of three different implant analogue materials (stainless steel, titanium, aluminium) in two die materials (Group A and Group B) with mean marginal gap values between implant analogue and abutment at different intervals (0, 3rd, 6th, 9th and 12th) by one way ANOVA

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For three implant analogue materials (SS, Ti, Al) of both die materials (Group A and Group B) at different intervals (0, 3rd, 6th, 9th and 12th) compared with “0” interval shows the P value of about 0.0001(i.e., P < 0.05). This shows that there was statistically significant difference between different intervals (0, 3rd, 6th, 9th and 12th) with “0” interval.

The order of mean difference of mean marginal gap between implant analogue and Abutment from “0” interval to “12th” interval of three different materials (Stainless steel, Titanium, Aluminium) in two die materials were:

Aluminium (1.47 μm and 1.45 μm) > SS (0.91 μm and 0.95 μm) >Titanium (0.62 μm and 0.64 μm).


   Discussion Top


A laboratory analogue is a replica of an implant, usually incorporated within a cast for a prosthetic reconstruction. The analogue provides a replica which shows the exact position of implant in patient's mouth. It is made by making an impression of the patient's teeth and implants by using the impression post to which the implant analogue is attached and using that impression to create a copy which exactly shows the anatomical and positional relation of the implant as it exists in the patient's mouth. This allows a dental professional or lab personnel to build the prosthesis and properly place back the final prosthesis.[6]

Mostly used implant analogue materials are Stainless steel, Titanium, Aluminium, Plastics and Zirconium. In the study most commonly used implant analogue materials are used such as Stainless steel, Titanium and Aluminium. Reuse of implant components are desirable for economic and environmental reason. Metal implant components may be more suitable for reuse because they can be easily resterilized. Implant analogues are one of the metal implant components that are appealing to clinicians for reuse. When implant analogues are reused, it is important to be assured that they are as accurate as new ones. Moreover, the number of times that the components can be reused safely and effectively should be determined. In the study the implant analogue was reused for 12 times and at every three intervals the implant analogue (0 interval taken as a control, 3rd interval, 6th interval, 9th interval, and 12th interval) was evaluated for any deformations.

As per the literature there was no study that evaluates the dimensional changes (internal and external diameter) of implant analogues, marginal gap between implant analogue and abutment after reuse at interval times. Reuse of implant analogue of three materials such as Stainless steel, Titanium, Aluminium for 12 times. In which 0 interval was taken as control. In this the screw and abutment was tightened and loosened for four times and the old screw was discarded and the new screw was taken for the next interval. Then the implant analogue was evaluated as following: (1) External diameter (2) Internal diameter and (3) Marginal gap between implant analogue and abutment. After multiple reuse of the implant analogue by screwing and unscrewing for four times at each interval with abutment and fresh/new screw. These were measured at an intervals of 0 as control and then 3rd, 6th, 9th and 12th interval.

External diameter of the implant analogue implies the diameter between the two outermost points at the collar end of the implant analogue. After repeated reuse the external diameter at the 3rd, 6th, 9th and 12th interval the values were same as the values at the 0 interval i.e., 3.92 mm for SS, 3.89 mm for Ti and 3.41 mm for Al implant analogues. The reason for no change in the external diameter are there was no mechanical damage to the external surface or no frictional contact with the components (i.e., abutment) and no direct force acting on the external surface and also the bulk of metal and toughness is the possible reason for no change of the implant analogue's external diameter while retrieving and reusing for multiple times (i.e., 0 to 12 times).

Internal diameter of the implant analogue implies the diameter between the two innermost points at the collar end of the implant analogue. The internal diameter for Stainless steel at 0 interval was 2.93 mm. After repeated reuse the internal diameter for the Stainless steel implant analogue at 3rd, 6th, 9th and 12th intervals were 2.93 mm, 2.95 mm, 2.96 mm, and 3.00 mm respectively in both group A and group B. This shows there is an increase in the internal diameter of the Stainless steel implant analogue by repeated reuse after the third interval. In this until 3rd interval there is no change in the internal diameter. The internal diameter for Titanium at 0 interval was 2.96 mm. After repeated reuse for Titanium implant analogues the internal diameter at 3rd, 6th, 9thintervals were 2.96 mm for both group A and group B but for 12th interval the internal diameter was 3.00 mm in group A samples and 3.01 mm in group B sample. In this there is no change in the internal diameter until 9th interval and change in internal diameter noticed by 12th time. So there may be change after 9th interval. The internal diameter for Aluminium at 0 interval was 2.70 mm. After repeated reuse the internal diameter for the Aluminium implant analogue at 3rd, 6th, 9th and 12th intervals were 2.70 mm, 2.74 mm, 2.83 mm, and 2.86 mm respectively in both group A and group B. This shows there is an increase in the internal diameter of the Aluminium implant analogue by repeated reuse after the third interval. In this there is no change in the internal diameter until 3rd interval and change in internal diameter noticed by 6th time. So there may be change after 3rd interval. The reason for changes in the internal diameter was “Adhesive type of wear” which occurs at the innermost surface of the implant analogue while placing the abutment and screwing and unscrewing repeatedly for about four times at each interval causes the loss of materials at the contacting surface due to friction which is the reason for increasing in the internal diameter.

The results of the study shows more changes are seen in the Aluminium implant analogue followed by the Stainless steel and Titanium implant analogue. The reason is that Aluminium material has lower hardness i.e., Aluminium is softer which causes more amount of frictional wear. On comparing the three materials the Titanium material is 3 to 4 times denser when compared with the Stainless steel which is 2.5 times denser than the Aluminium. This is the possible reason for Aluminium implant analogues to exhibit more wear at the contacting surface with the abutment. It is observed from the study results that there is an increase in the internal diameter of the Aluminium implant analogues more followed by Stainless steel implant analogues and Titanium implant analogues.

The order of mean difference of mean internal diameter of implant analogues from “0” interval to “12th” interval of three different materials (Stainless steel, Titanium, Aluminium) are:

Aluminium (0.16 mm) > Stainless steel (0.07 mm) > Titanium (0.04 mm).

When there is an Internal diameter variation the fit with the abutment might not be proper, which might lead to improper alignment/seating of the abutment or prosthesis, which further lead to the screw loosening due to abnormal force transfer and also wobbling of the prosthesis contributing to marginal bone loss. So repeated reuse of implant analogue might be the contributing factor for implant prosthesis failure.

Marginal gap between implant analogue and abutment

The abutment-implant analogue interface represents a critical areas in implant restoration. This interface errors further carry over towards the implant–abutment interface which was a misfit. A misfit between components is recognised as a major concern in implant rehabilitation because it may lead to mechanical problems, mainly the stability of the connection. Furthermore, the presence of a microleakage may favor bacterial colonization at the interface, which may cause the inflammation of peri-implant tissues.[7] A key objectives of this study was to raise the awareness of clinicians in terms of the marginal gap at the implant analogue–abutment interface. According to previous studies by Jansen et al., the mean acceptable size of marginal gap/micrograp was between 2.0 to 6.0 μm and according to Tsuge et al., the mean size of marginal gap/microgap range from 2.3 to 5.6 μm.[8] According to El-Ashry et al. the biologic factors are generally considered multifactorial, mechanical factors such as the implant–abutment precise fit and the abutment screw preload are involved in the success of implant rehabilitation. The preload loss during occlusal load with the prosthesis in function favours a lack of stability and misfit of the implant-abutment connection and this can result in stress increase in the implant and connection components.[9]

From the results obtained in this study, for Stainless steel implant analogues of Group A from “0” interval to “3rd” interval there was a slight change in the mean marginal gap value that was about 0.23 μm (i.e., at “0” interval the value was 0.87 μm and at 3rd interval the value was 1.10 μm). For further intervals there was an increase in the mean marginal gap value when compared with “0” interval i.e., for 6th interval the value was 1.45 μm, for 9th interval the value was 1.66 μm and for 12th interval the value was 1.78 μm. The difference between the marginal gap values of further intervals compared with “0” interval were 0.58 μm, 0.79 μm and 0.91 μm. This shows that there was an increase in the mean marginal gap value while reusing. For Stainless steel implant analogues of Group B from “0” interval to “3rd” interval there was a slight change in the mean marginal gap value that was about 0.26 μm (i.e., at “0” interval the value was 0.85 μm and at 3rd interval the value was 1.11 μm). For further intervals there was an increase in the mean marginal gap value when compared with “0” interval i.e., for 6th interval the value was 1.44 μm, for 9th interval the value was 1.65 μm and for 12th interval the value was 1.79 μm. The difference between the marginal gap values of further intervals compared with “0” interval were 0.59 μm, 0.80 μm and 0.95 μm. This shows that there was an increase in the mean marginal gap value while reusing.

For Titanium implant analogues of Group A from “0” interval to “3rd” interval there was a slight change in the mean marginal gap value that was about 0.07 μm (i.e., at “0” interval the value was 0.71 μm and at 3rd interval the value was 0.78 μm). For further intervals there was an increase in the mean marginal gap value when compared with “0” interval i.e., for 6th interval the value was 0.95 μm, for 9th interval the value was 1.19 μm and for 12th interval the value was 1.32 μm. The difference between the marginal gap values of further intervals compared with “0” interval were 0.24 μm, 0.48 μm and 0.62 μm. This shows that there was an increase in the mean marginal gap value while reusing. For Titanium implant analogues of Group B from “0” interval to “3rd” interval there was a slight change in the mean marginal gap value that was about 0.10 μm (i.e., at “0” interval the value was 0.69 μm and at 3rd interval the value was 0.79 μm). For further intervals there was an increase in the mean marginal gap value when compared with “0” interval i.e., for 6th interval the value was 0.95 μm, for 9th interval the value was 1.19 μm and for 12th interval the value was 1.33 μm. The difference between the marginal gap values of further intervals compared with “0” interval were 0.26 μm, 0.49 μm and 0.64 μm. This shows that there was an increase in the mean marginal gap value while reusing.

For Aluminium implant analogues of Group A from “0” interval to “3rd” interval there was a slight change in the mean marginal gap value that was about 0.32 μm (i.e., at “0” interval the value was 0.86 μm and at 3rd interval the value was 1.17 μm). For further intervals there was an increase in the mean marginal gap value when compared with “0” interval i.e., for 6th interval the value was 1.52 μm, for 9th interval the value was 1.81 μm and for 12th interval the value was 2.33 μm. The difference between the marginal gap values of further intervals compared with “0” interval were 0.67 μm, 0.96 μm and 1.47 μm. This shows that there was an increase in the mean marginal gap value while reusing. For Aluminium implant analogues of Group B from “0” interval to “3rd” interval there was a slight change in the mean marginal gap value that was about 0.32 μm (i.e., at “0” interval the value was 0.87 μm and at 3rd interval the value was 1.19 μm). For further intervals there was an increase in the mean marginal gap value when compared with “0” interval i.e., for 6th interval the value was 1.51 μm, for 9th interval the value was 1.81 μm and for 12th interval the value was 2.32 μm. The difference between the marginal gap values of further intervals compared with “0” interval were 0.65 μm, 0.94 μm and 1.45 μm. This shows that there was an increase in the mean marginal gap value while reusing.

This show that the after repeated reuse the marginal gap between the implant analogue and abutment is more for the Aluminium implant analogue material followed by Stainless steel and Titanium.

The order of mean difference of mean marginal gap between implant analogue and Abutment from “0” interval to “12th” interval of three different materials (Stainless steel, Titanium, Aluminium) in two die materials were:

Al (1.47 μm and 1.45 μm) > S.S (0.91 μm and 0.95 μm) >Ti (0.62 μm and 0.64 μm).

Order of the marginal gap values between implant analogue and abutment for three materials were as follow by considering their values at time intervals:

Aluminium material > Stainless steel material > Titanium material.

The possible reason is that the abutment screw acts as a spring stretched by preload, which is maintained by the frictional fit of the threads. External forces can create a vibratory movement and cause the threads to “back off “ which leads to a reduction in effective preload and diminishes the ability of the screw to maintain the joint stability thereby increasing the implant–abutment interface gap.[9]

Titanium material is denser and damage to internal threads of analogues is less so there is better fit between analogue and abutment but the fit is increased due to friction wear of internal threads when it is used for multiple times. The undamaged new screw threads fit is altered which might be the possible reason for increase in the marginal gap. Aluminium material is less dense than Stainless steel and Titanium material, so there is a more amount of friction wear occurs at the internal threads of the Aluminium materials which may be the possible reason for more amount of increase in the marginal gap. Based on the results obtained, the marginal gap between the implant analogue and abutment of all the three materials are less than the acceptable range (2.0 μm to 6.0 μm).[8]


   Conclusion Top


The following conclusions were drawn based on the results obtained in the present in vitro study which was conducted to assess the effect of multiple reuse of implant analogues of three different materials (Stainless steel, Titanium, Aluminium) on the dimensional accuracy (external diameter and internal diameter) and the marginal gap between analog and abutment by using two die materials was:

  • There was no change in the external diameter of three materials of implant analogue in both die materials
  • There was an increase in the internal diameter of implant analogs in which the aluminum material has more increase from 0 to 12th interval followed by the stainless steel and titanium implant analogs in both die materials. In between the two die materials, no difference was observed
  • There was an increase in the marginal gap between implant analog and abutment in which the aluminum material has more increase from 0 to 12th interval followed by the stainless steel and titanium implant analogs in both die materials. In between the two die materials, no difference was observed
  • From the study, the following inferences is drawn: that titanium implant analogs can be used for more than three times but not more than six times, stainless steel implant analogs can be used for not more than three times, and the aluminium implant analogs can be used for one time only. Hence, among the three materials, titanium implant analogs were most efficient for reuse.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
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    Figures

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