An In Vitro Trial to Estimate the Retention Ability of Luting Agents Utilized with Dental Implant-Supported Prosthesis

Abstract

Aim:

The trial's goal was to assess the retentiveness of specially formulated implant cement besides comparing it to dental cements that are widely utilized by means of implant systems.

Materials and Procedures:

Twenty implant analogs were implanted in auto-polymerizing acrylic resin blocks and bonded to titanium abutments. Fifty uniform copings were waxed and cast unswervingly onto the abutment. (1) Resin-bonded zinc oxide eugenol cement, (2) purposefully designed implant cement, (3) zinc phosphate cement, (4) zinc polycarboxylate cement, and (5) glass ionomer cement were the cements used. Following cementation, each sample was pulled out by utilizing a widespread testing machine, and the stresses necessary to confiscate the crowns were recorded. The ANOVA and Bonferroni tests were used to examine the mean values and standard deviations of cement failure loads.

Results:

Zinc polycarboxylate cement had the peak mean cement failure load, followed by glass ionomer cement. Zinc phosphate cement had the next highest mean cement failure load, followed by resin-bonded zinc oxide eugenol cement. The mean cement failure load for Premier implant cement was the lowest. The difference in mean cement failure loads across the groups was statistically significant (P < 0.001).

Conclusion:

The findings do not imply that one type of cement is superior to another, but they do present a ranking directive of cements based on their capacity to maintain the prosthesis and facilitate retrievability.

INTRODUCTION

The triumph of implant therapy is dependent not only on the implant fixture's osseointegration but also on the veracity of the link amid the prosthetic superstructure besides the fixture. For implant-supported fixed prostheses, the best approach among cement and screw-retained procedures has long been debated, and there is no consensus among practitioners.[1,2] Both have rewards and hindrances when compared with one another. Nevertheless, owing to the absenteeism of passive fit of screw-retained restorations, more stress accumulates around the implants.[3] Cement-retained prosthesis has become the preferred choice for implant restorations to overcome the restrictions of screw-retained prostheses. Cemented restorations have superior esthetics and occlusion when compared to screw-retained restorations.[4] The majority of implant dentistry cements are now intended for usage with prostheses bonded to natural teeth. Recently, cements specifically made for this purpose have been introduced, with makers claiming a number of benefits. However, there have been very few studies on implant cements that have been carefully formulated. The goal of the current study was to determine the cement failure load (CFL) of a specially premeditated implant cement and compare it with dental cements typically utilized in implant systems.

MATERIALS AND METHODS

For the internal hex implant of diameter 4.2 mm, 20 implant analogs and 20 implant abutments were employed. A dental surveyor was used to mount nine implant analogs in individual auto-polymerizing acrylic resin blocks (2.9 cm × 1.4 cm). Each implant analog was fitted with a titanium abutment and torqued at 35 Ncm with a torque wrench. Before cementation, the occlusal access aperture and the screw-thread of the abutments were filled with modelling wax. One implant analog was placed in a 3 cm × 3 cm block of auto-polymerizing acrylic resin. An auto-polymerizing acrylic resin master coping was created unswervingly on the implant abutment. A cylindrical custom tray of auto-polymerizing acrylic resin was built to form a mold of the master coping by means of elastomeric impression material based on the measurements of the resin block. Fifty standardized copings were waxed unswervingly onto the unaltered abutment and sprued using this silicone mold. The sprue required to be at least 15-mm long and parallel to the coping's line of draw to be utilized as the mechanism for attaching the metal coping to the universal testing machine crosshead later on. Finished wax patterns were studied, and Ni–Cr alloy was cast. The acrylic block (3 cm × 3 cm) with installed implant analog–abutment assembly was reduced to the same size as other acrylic blocks, 2.9 cm × 1.4 cm, when all the metal copings were ready. The castings were allocated into five experimental groups, with ten test specimens in each group. Metal coping fitting surfaces were then added and blasted for 5 s with 50 m aluminum oxide particles. Each metal coping was set on the abutment and checked under magnification for surface imperfections on the intaglio surface, as well as marginal fit and complete seating of the coping on the abutment. Next, all of the metal copings' intaglio surfaces and the abutment surfaces were steam-cleaned. The specimens were tensile-loaded till separation to measure the retentive strength after keeping the implant analog abutment coping assemblies in physiological saline solution for 24 h at 37°C. The lower tensile jig was used to grab acrylic blocks, and the copings' sprues were linked to the upper tensile jig. A tensile load of 2000 N was applied to the copings along with a steady crosshead speed of 0.5 mm/min until they separated. The loads at the point of failure were measured in Newtons. To remove any remaining cement, the abutment surfaces were steam-cleaned. The universal implant scaler was used to remove any residual cement on the abutment surfaces as necessary. Following that, all of the test specimens from various groups of luting cements were put to the test.

RESULTS

The maximum loads at failure, expressed in Newtons, were included in the data (N). A one-way ANOVA and multiple comparisons (posthoc testing) by utilizing the Bonferroni test were performed to identify which pair of groups had a significant difference. Table 1 lists the sample size, average, standard deviation, minimum, and maximum values of the cement failure loads for the numerous cements. Glass ionomer cement had the highest mean cement failure load, followed by zinc polycarboxylate cement. The highest mean cement failure load was found in zinc phosphate cement, followed by resin-bonded zinc oxide eugenol cement. Premier implant cement had the lowest mean cement failure load. There was a statistically significant alteration in the mean cement failure loads across the groups (P = 0.001).

Table 1.

Analysis of variance for cement failure loads (n)

Cement	n	Mean	SD	Min	Max	F	P
Group I (Kalzinol)	20	492.45	8.66	392.00	520.10	1958.729	<0.001
Group II (Premier implant cement)	20	312.77	19.82	358.30	458.60
Group III (De Trey Zinc)	20	738.20	30.85	684.80	646.10
Group IV (Poly-F)	20	920.07	14.43	747.00	788.30
Group V (G C Gold Label)	20	660.26	12.67	658.70	886.10

DISCUSSION

According to Hill et al.,[5] besides the type of the luting agent, the longevity of restoration depends on the abutment's height, taper, oral hygiene, and the luting agent retention. Pan et al.[6] stated that the retention of the crown was also affected by several other factors such as the geometric configuration, thermal stress, fabrication technique, and the usage of more abutments. On the contrary, luting agents also prevent saliva leakage and bacterial accumulation to protect the peri-implant tissues. In this study, luting agents were tested and compared only for retention strength; microleakage and bacterial accumulation of these products can be studied in future works. The extra or incorrect milling of the abutment causes a decrease in the luting surface; therefore, de-cementation may occur. Thus, retrieving the crown due to restoration maintenance and hygienic controls of the peri-implant tissues may be required in clinical practice. Alvarez-Arenal et al.[7] reported that urethan-based non-eugenol temporary cement is a better choice if the clinician is unsure whether mechanical or biological complications may occur. High retention strength is not always a good result for implant-supported restorations because the removal of restorations may be required at any time and must be done without any damage to implants. Because a critical retention value to keep the restorations in place stable is not mentioned in the literature, clinicians should decide on their own by considering the retention values of cement. In this study, by comparing the bond strength results of different cements with varying characteristics, guideline formation for clinicians to choose the appropriate type and adequate amount of cement for the individual case was aimed. As the SARC belonging to the same group in this study showed significantly different retention values, this finding may affect the clinician's choice regarding their retention strength rates. Ease of removal of excess cement is of great importance at this point and must be kept in mind at the time of selecting the luting agent.[8] At this point, temporary cement may be a preferred option for their ease of cleaning.

Another factor that has been found to aid retention is the undercut generated contained by the screw access opening.[9,10,11] The removal force of a coronal restoration can be reduced by completely filling the screw access channel, according to Emms and Naik. Due to the unique design of the samples, which did not have a screw access channel, this problem was avoided in this investigation.[12,13] Because temporary cement has a weak chemical affinity for adhering to the substrate surface, the crowns are mostly held in place by a mechanical interlocking mechanism.[10] Metal surfaces may be harmed by leachable chemicals from rough varieties of dental cement. According to several studies, various dental cements affect the protective titanium oxide layer, causing color variations on the titanium surface.[14] Color change has been linked to titanium alloy corrosion, which can result in bond strength values that are higher than expected.[10] Corrosion of titanium alloy increases pathogenic microbial adhesion as well.[11] Despite their great binding strength, the influence of the PC tested on the implant surface must be carefully evaluated. Due to the brief period of the trial, no such corrosion effects were identified in the current study. CZPC's greatest bond strength score may be related to corrosion products that are not as noticeable in this cement group. This, however, has not yet been studied.

CONCLUSION

Within the constraints of this study, definitive cements provide a higher cement failure load than provisional cement besides explicitly developed implant cement. Of all the cements tested, zinc polycarboxylate cement has the greatest mean cement failure load, followed by glass ionomer cement and zinc phosphate cement. In this investigation, the specially developed implant cement (Premier implant cement) achieved the lowest retentive value. Nonetheless, the prosthesis's low retentive strength may make it easier to retrieve it. The findings do not advocate that one cement type is superior to another, but they do rank the cements in terms of their capacity to hold the prosthesis in place and allow retrieval.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.