Retentiveness of various luting agents used with implant-supported prosthesis: an in vitro study

Pull-Off Forces on Implant-Supported Single Restorations by Sticky Food: An In Vitro Study

OBJECTIVE

To investigate the pull-off forces on implant-supported restorations caused by sticky food, to understand how much retention force cemented restorations must have to withstand chewing forces without unintentional retention loss. The influence of food type, restoration design, and surface treatment were investigated.

MATERIAL AND METHODS

Monolithic implant-supported CAD/CAM zirconia crowns were fabricated and divided into groups according to their design: no (NC), flat (FC) and high cusps (HC) and subdivided according to surface roughness: rough (r) and smooth (s) (n = 10/group). NC represented the control group. The crowns were fixed in a universal testing machine opposite to each other. Four sticky foods (caramel, fruit jelly, candy strips and licorice) and a resin crown remover were tested. These were heated (36.4°C), placed between the crowns and compressed, then tensile strength tests were performed. The maximum pull-off force was recorded (Newton [N]). Statistical analysis was performed using 3-way ANOVA.

RESULTS

The highest mean pull-off force among food samples was with caramel_HC_r (12.09 ± 1.26 N), whereas the lowest was with licorice_FC_s (3.21 ± 0.15 N). For the resin crown remover, a mean pull-off force of 55.41 ± 3.87 N was measured in the HC_r group. Both food type and crown design showed a significant influence on pull-off force (p < 0.001), whereas no significant effect was reported with different surface roughnesses (p = 0.344).

CONCLUSION

This study reported pull-off forces of up to 20 N between all-ceramic restorations caused by sticky food. The clinical implication of these findings is that a cemented implant-restoration must have a minimum retention force of 20 N to withstand unintentional displacement during function.

Resistance to Torsion of Cement vs Screw-Retained Abutments Under a Tangential Load: A Pilot Study

The aim is to compare the resistance to torsion between 2 implant systems with internal hexagon connection: one using screw-retained abutments (Titanium Fix) and the other using cementable abutments (ITEC) under a tangential load. An in vitro experimental study was carried out. Fourteen implants, 7 implants from each system, were included in this study. The implants were placed at a 45° angle into metal blocks to simulate their position in the maxilla. Then, implants were subjected to a resistance test on a CMT5L universal testing machine, and the maximum load was applied to each sample. The maximum force with which the torsion was achieved in each sample was analyzed. The data were tested using the Shapiro-Wilk test and showed normal distribution. Student t test was used to examine statistical significance between the two groups, and the P value was set at P < .05. There was a statistically significant difference between the two groups (P = .001). ITEC implants with a cementable abutment showed greater flexural strength compared to the Titanium Fix with a screwed abutment implant system. The cemented abutment showed more resistance to torsion against a tangential load compared with the screwed abutment.

Effect of cement type on vertical marginal discrepancy and residual excess cement in screwmentable and cementable implant-supported monolithic zirconia crowns

The purpose of this study was to investigate the vertical marginal discrepancy (VMD) and residual excess cement (REC) of cementable and screwmentable monolithic zirconia crowns cemented with different types of cement. Abutments were attached to 40 implant analogues. Crowns were created using computer-aided design/computer-aided manufacturing technology from monolithic zirconia blocks, either with or without a screw access hole (SAC). Crowns created both ways were split into two groups and cemented with resin and zinc polycarboxylate cement under a 5-kg weight. VMD and REC values were evaluated using an X20 zoom stereomicroscope. Data were analysed using two-way ANOVA and the Bonferroni test. According to the two-way ANOVA results, REC measurements differed significantly in the crown design and cement groups. However, whilst VMD values were significantly different in both crown design groups, there was no significant difference in the cement groups. According to the Bonferroni test results, the highest REC (157.241 ± 44.29 µm) and VMD (68.052 ± 16.19 µm) values were found in the crowns without SAC and cemented with zinc polycarboxylate. Screwmentable crowns are more effective than cementable crowns in reducing REC and VMD. Whilst polycarboxylate cement reduces VMD in screwmentable crowns, resin cement is more suitable for cementable crowns.

An Evaluation of the Effectiveness of Various Luting Cements on the Retention of Implant-Supported Metal Crowns

Background and objective Cement-retained prostheses have replaced screw-retained prostheses as the preferred restoration in recent years in order to overcome the latter's limitations. In this study, four different luting cements were compared to evaluate their efficacy on the retention of cement-based metal crowns to implant abutments. Materials and methods In the right and left first molar regions, four implant analogs (Internal Hex, Adin Dental Implant Systems Ltd., Tel-Aviv, Israel) were screwed into epoxy resin casts (Araldite CY 230-1 IN, India) that were positioned perpendicular to the cast's plane. Four metal copings were created and cemented. Group A: polycarboxylate cement (DUR) (DurelonTM, 3M Espe, St. Paul, MN); Group B: PANAVIA™ F 2.0 dual-cure resin cement (Kuraray America, Inc., New York, NY); Group C: resin-modified glass ionomer (3M™ RelyX™ Luting, 3M Espe); and Group D: non-eugenol temporary resin cement (Kerr-Temp, KaVo Kerr, Brea, CA) were used to cement crowns. To check the retention capacity, samples were put through a pull-out test on an Instron universal testing machine (TSI‑Tecsol, Bengaluru, India) with a crosshead speed of 0.5 mm/min. Each coping's de-cementing load was noted, and average values for every sample were computed and statistically analyzed. Results The findings demonstrated that non-eugenol temporary resin implant cement has the lowest retention value at 138.256 N, followed by resin-modified glass ionomer cement at 342.063 N, polycarboxylate luting cement at 531.362 N, and resin cement at 674.065 N. The average difference in retentive strength across all four groups was statistically very significant (p=0.001). Conclusion Based on our findings, non-eugenol temporary resin implant cement enables simple retrievability of the prosthesis in the event of a future failure and is appropriate for implant restorations with cement retention. Also, cements made of polycarboxylate and resin have the highest retention values.

The effect of different cleansing methods for removing temporary cement on the tensile bond force of permanently cemented implant-supported metal copings: An in vitro study

Objectives

Complete cleaning of temporary cement before permanent cementation of cement‐retained implant‐supported prosthesis (CISP) when recementing the crown is critical. This study evaluated the effect of different cleaning methods for removing traces of temporary cement on the final tensile bond force (TBF) of CISP recemented with resin cement.

Materials and Methods

Seventy computer‐aided design/computer‐aided manufacturing metal implant‐supported copings were prepared and distributed into seven groups (N = 10). Copings of six groups (60 samples) were cemented with temporary cement with eugenol and subjected to 5000 thermocycling. After debonding by a universal testing machine, the internal surfaces of the copings were cleaned using one of the six following methods: 1‐an ultrasonic water bath (UW), 2‐sandblasting, then washing with water (SW), 3‐sandblasting and an ultrasonic water bath (SUW), 4‐an ultrasonic isopropyl alcohol bath (UA), 5‐sandblasting, then washing with isopropyl alcohol (SA) or 6‐sandblasting and an ultrasonic isopropyl alcohol bath (SUA). Then the subjects were subsequently cemented by dual‐cure self‐adhesive resin cement. In the seventh group (control, N = 10), the copings were cemented by dual‐cure self‐adhesive resin cement without the temporization phase. The TBF was tested using a universal testing machine with a cross‐head speed of 1 mm/min. Two‐way analysis of variance (ANOVA) and post‐hoc Tamhane tests were used for statistical analysis at a significance level of α = .05.

Results

The maximum mean of TBF value was observed in SUA group (845 ± 203 N), and the minimum was observed in the temporary cement group (49 ± 20 N). All groups which were cleaned with isopropyl alcohol showed significantly higher TBF values compared with those cleaned with water.

Conclusions

Cleaning of the inner surface of metal copings after debonding with sandblasting and isopropyl alcohol results in the highest value of TBF by eliminating the effect of remaining eugenol and removing traces of temporary cements.

Influence of Non-Thermal Atmospheric Pressure Plasma Treatment on Retentive Strength between Zirconia Crown and Titanium Implant Abutment

The aim of this study is to investigate the effect of non-thermal atmospheric pressure plasma (NTP) on retentive strength (RS) between the zirconia crown and the titanium implant abutment using self-adhesive resin cement. Surface free energy (SFE) was calculated on 24 cube-shaped zirconia blocks, and RS was measured on 120 zirconia crown-titanium abutment assemblies bonded with G-CEM LinkAce. The groups were categorized according to the zirconia surface treatment as follows: Control (no surface treatment), NTP, Si (Silane), NTP + Si, Pr (Z-Prime Plus), and NTP + Pr. Half of the RS test assemblies were aged by thermocycling for 5000 cycles at 5–55 °C. The SFE was calculated using the Owens-Wendt method, and the RS was measured using a universal testing machine at the maximum load until failure. One-way analysis of variance (ANOVA) with post-hoc Tukey honestly significant difference (HSD) was performed to evaluate the effect of surface treatments on the SFE and RS. Independent sample t-test was used to compare the RS according to thermocycling (p < 0.05). For the SFE analysis, the NTP group had a significantly higher SFE value than the Control group (p < 0.05). For the RS test, in non-thermocycling, the NTP group showed a significantly higher RS value than the Control group (p < 0.05). However, in thermocycling, there was no significant difference between the Control and NTP groups (p > 0.05). In non-thermocycling, comparing with the NTP + Si or NTP + Pr group, there was no significant difference from the Si or Pr group, respectively (p > 0.05). Conversely, in thermocycling, the NTP + Si and NTP + Pr group had significantly lower RS than the Si and Pr group, respectively (p < 0.05). These results suggest that NTP single treatment for the zirconia crown increases the initial RS but has little effect on the long-term RS. Applied with Silane or Z-Prime Plus, NTP pre-treatment has no positive effect on the RS.

Effect of different surface treatments on the shear bond strength of luting cements used with implant-supported prosthesis: An in vitro study

PURPOSE

The aim of this study was to investigate the shear bond strength of luting cements used with implant retained restorations on to titanium specimens after different surface treatments.

MATERIALS AND METHODS

One hundred twenty disc shaped specimens were used. They were divided into three groups considering the surface treatments (no treatment, sandblasting, and oxygen plasma treatment). Water contact angle of specimens were determined. The specimens were further divided into four subgroups (n=10) according to applied cement types: polycarboxylate cement (Adhesor Carbofine-AC), temporary zinc oxide free cement (Temporary Cement-ZOC), non eugenol provisional cement for implant retained prosthesis (Premier Implant Cement-PI), and non eugenol acrylic-urethane polymer based provisional cement for implant luting (Cem Implant Cement-CI). Shear bond strength values were evaluated. Two-way ANOVA test and Regression analysis were used to statistical analyze the results.

RESULTS

Overall shear bond strength values of luting cements defined in sandblasting groups were considerably higher than other surfaces (P<.05). The cements can be ranked as AC > CI > PI > ZOC according to shear bond strength values for all surface treatment groups (P<.05). Water contact angles of surface treatments (control, sandblasting, and plasma treatment group) were 76.17° ± 3.99, 110.45° ± 1.41, and 73.80° ± 4.79, respectively. Regression analysis revealed that correlation between the contact angle of different surfaces and shear bond strength was not strong (P>.05).

CONCLUSION

The retentive strength findings of all luting cements were higher in sandblasting and oxygen plasma groups than in control groups. Oxygen plasma treatment can improve the adhesion ability of titanium surfaces without any mechanical damage to titanium structure.

Evaluation of the Effect of Fluoride-containing Luting Cements on Titanium and Its Effect on the Shear Bond Strength

Context:

The most appropriate luting agent for titanium crowns is yet to be determined. Commonly used cements for luting titanium restorations give off leachable ions which may cause surface interaction with the titanium.

Aims:

The purpose of this study was to determine the shear bond strength of four grades of commercially pure titanium and Ti 6Al 4V with different cements and to examine for any surface physical changes.

Settings and Design:

The three luting cements, i.e., zinc polycarboxylate cement, glass ionomer cement, and zinc phosphate cement, were used to evaluate their effect on titanium. Ni Cr was used as a control.

Methods and Material:

The metal rods were milled to discs of 6 mm diameter and 4 mm height. Freshly extracted maxillary first molars, mounted in resin blocks, were sliced horizontally at occlusal third of the tooth. The discs were cemented to the sliced surface of the tooth with the three luting cements. The models were subjected to the shear bond strength test. Statistical analysis used: The data collected were analyzed statistically with one way ANOVA. A representative specimen of each group was observed under a scanning electron microscope.

Results:

The mean values ranged from 0.31 to 15.6 MPa. The shear bond strength values of the zinc polycarboxylate cement group were significantly high (P < 0.05). Corrosion of the titanium alloy luted with zinc polycarboxylate cement was observed.

Conclusions:

Cementation with zinc polycarboxylate cement provided high shear bond strength, but showed corrosion on titanium.

Retention of zirconia copings over smooth and airborne-particle-abraded titanium bases with different resin cements

STATEMENT OF PROBLEM

How cement type and the surface treatment of a titanium base affect the retention of zirconia copings on titanium bases is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the dislodging forces of zirconium oxide copings cemented on implant-supported titanium bases with different luting agents and to examine the influence of airborne-particle abrasion on titanium surfaces.

MATERIAL AND METHODS

Thirty implant laboratory analogs (BioHorizons) were fixed in metal blocks, and 30 prosthetic titanium bases (BioHorizons) were tightened with 35 Ncm of torque. Zirconium oxide copings with a luting-gap size of 30 μm were produced by using the Lava (3M ESPE) technology. The specimens were bonded to the titanium bases with 3 different resin cements (G-CEM LinkAce, RelyX U200, and Ceka Site). The specimens were kept in artificial saliva at 37°C for 24 hours and then subjected to a dynamic loading of 5000 cycles with a mastication simulator (SD Mechatronic) with thermocycling between 5°C and 55°C. The tensile force was measured by using a universal testing machine (Zwick/Roell) at a crosshead speed of 5 mm/min. After the measurement, the cement was cleaned from the titanium bases and zirconia copings. The titanium bases were airborne-particle abraded with 50-μm aluminum oxide (Al₂O₃) particles, and the bonding process was repeated. The statistical analysis included descriptive analysis, 2-way ANOVA, the Tukey post hoc, and simple main effect tests (α=.05).

RESULTS

Bond strengths were significantly different according to the cement type used and before and after airborne-particle abrasion (P<.05). The cement retentiveness before airborne-particle abrasion was as follows: G-CEM LinkAce (1338 ±69 N)>RelyX U200 (665 ±36 N)>Ceka Site (469 ±22 N). The differences among all the cement types before airborne-particle abrasion were statistically significant (P<.05). After airborne-particle abrasion, retention decreased in all the groups, and the ranking of the cements' retentiveness remained the same: G-CEM LinkAce (662 ±65 N)>RelyX U200 (352 ±21 N)>Ceka Site (122 ±17 N). After airborne-particle abrasion, the differences among all the cements remained statistically significant (P<.05). The comparison within the groups before and after airborne-particle abrasion revealed that abrading the titanium bases with 50-μm Al₂O₃ decreased the bond strength for all the tested cements.

CONCLUSIONS

The cement type had a significant influence on the retention of the zirconia copings, and abrading the titanium bases with 50-μm Al₂O₃ significantly decreased the dislodging force of the coping from the titanium base.

The Effect of CAD/CAM Crown Material and Cement Type on Retention to Implant Abutments

PURPOSE

To evaluate the pullout resistance of CAD/CAM implant-supported crowns cemented with provisional and definitive cements on Ti-base implant abutments.

MATERIALS AND METHODS

Sixty crowns were milled for use in Ti-base implant abutments and divided (n = 15/group) according to material, as follows: (a) [Pr] Temporary acrylic resin; (b) [Co-Cr] Cobalt-Chromium alloy; (c) [Zr] polycrystalline zirconia; and (d) [Ti] titanium. The cementation was performed with RelyX Temp NE (RxT) cement or RelyX U200 self-etching resin cement, under a 50 N (5 kg) load for 10 minutes. Twenty-four hours after cementation, the crowns were subjected to the pullout test in a universal test machine, at a 1.0 mm/min crosshead speed. The tests were performed first without cement to evaluate frictional resistance (Baseline), then with provisional cement (RelyX Temp NE without cement again (Baseline After RxT), and finally with resin cement (U200). The results were analyzed by ANOVA and Tukey test (p < 0.05).

RESULTS

Data evaluation as a function of cement type demonstrated the superiority of resin-based cements relative to provisional and baseline groups (p < 0.01). While Co-Cr crowns presented the highest pullout strength values, Pr showed the lowest values (data collapsed over cement) (p < 0.001). Retentiveness data as a function of both factors demonstrated similar pullout resistance between groups without cement (p < 0.001), except Zr baseline. Also, Co-Cr presented higher pullout strength compared to other materials.

CONCLUSIONS

Self-adhesive resin cement exhibited superior retention compared to temporary cement, regardless of crown material. Co-Cr and titanium presented higher levels of retention to Ti-base abutment after being cemented.

Load-Bearing Capacity and Retention of Newly Developed Micro-Locking Implant Prosthetic System: An In Vitro Pilot Study

The aim of this study was to introduce the newly developed micro-locking implant prosthetic system and to evaluate the resulting its characteristics. To evaluate load-bearing capacity, 25 implants were divided into five groups: external-hexagon connection (EH), internal-octagon connection (IO), internal-hexagon connection (IH), one-body implant (OB), micro-locking implant system (ML). The maximum compressive load was measured using a universal testing machine (UTM) according to the ISO 14801. Retention was evaluated in two experiments: (1) a tensile test of the structure modifications of the components (attachment and implant) and (2) a tensile test after cyclic loading (total 5,000,000 cycles, 100 N, 2 Hz). The load-bearing capacity of the ML group was not significantly different from the other groups (p > 0.05). The number of balls in the attachment and the presence of a hexagonal receptacle did not show a significant correlation with retention (p > 0.05), but the shape of the retentive groove in the implant post had a statistically significant effect on retention (p < 0.05). On the other hand, the retention loss was observed during the initial 1,000,000 cycles, but an overall constant retention was maintained afterward. Various preclinical studies on this novel micro-locking implant prosthetic system should continue so that it can be applied in clinical practice.

Effects of abutment diameter, luting agent type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments

PURPOSE

The aim of this study was to evaluate the effects of abutment diameter, cement type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments.

MATERIALS AND METHODS

Sixty abutments with two different diameters, the height of which was reduced to 3 mm, were vertically mounted in acrylic resin blocks with matching implant analogues. The specimens were divided into 2 diameter groups: 4.5 mm and 5.5 mm (n=30). For each abutment a CAD/CAM metal coping was manufactured, with an occlusal loop. Each group was sub-divided into 3 sub-groups (n=10). In each subgroup, a different cement type was used: resin-modified glass-ionomer, resin cement and zinc-oxide-eugenol. After incubation and thermocycling, the removal force was measured using a universal testing machine at a cross-head speed of 0.5 mm/min. In zinc-oxide-eugenol group, after removal of the coping, the cement remnants were completely cleaned and the copings were re-cemented with resin cement and re-tested. Two-way ANOVA, post hoc Tukey tests, and paired t-test were used to analyze data (α=.05).

RESULTS

The highest pulling force was registered in the resin cement group (414.8 N), followed by the re-cementation group (380.5 N). Increasing the diameter improved the retention significantly (P=.006). The difference in retention between the cemented and recemented copings was not statistically significant (P=.40).

CONCLUSION

Resin cement provided retention almost twice as strong as that of the RMGI. Increasing the abutment diameter improved retention significantly. Re-cementation with resin cement did not exhibit any difference from the initial cementation with resin cement.

Clinical evaluation of an improved cementation technique for implant-supported restorations: a randomized controlled trial

BACKGROUND

Cement remnants were frequently associated with peri-implantitis. Recently, a shoulderless abutment was proposed, raising some concern about cement excess removal.

AIM

To compare different cementation techniques for implant-supported restorations assessing the amount of cement remnants in the peri-implant sulcus. Additional aim was to compare the effect of these cementation techniques using two different abutment designs.

MATERIAL & METHODS

Forty-six patients requiring double implant-supported restoration in the posterior maxilla were randomly divided in two groups according to the cementation modality: intraoral and extraoral. According to the abutment finishing line, implants in each patient were randomly assigned to shoulderless or chamfer subgroup. In the intraoral group, crowns were directly seated onto the titanium abutment. In the extraoral group, crowns were firstly seated onto a resin abutment replica and immediately removed, then cleansed of the cement excess and finally seated on the titanium abutment. After cement setting, in both groups, cement excess was carefully tried to remove. Three months later, framework/abutment complexes were disconnected and prepared for microscopic analysis: surface occupied by exposed cement remnants and marginal gaps were measured. Additionally, crown/abutment complexes were grinded, and voids of cement were measured at abutment/crown interface. Related-samples Friedman's two-way analysis of variance by ranks was used to detect differences between groups and subgroups (P ≤ 0.5).

RESULTS

At the end of the study, a mean value of 0.45 mm² (±0.80), 0.38 mm² (±0.84), and 0.065 mm² (±0.13) and 0.07 mm² (±0.15) described surface occupied by cement remnants in shoulderless and chamfer abutment with intraoral cementation and shoulderless and chamfer abutment with extraoral cementation, respectively. A mean value of 0.40 mm² (±0.377), 0.41 mm² (±0.39) and 0.485 mm² (±0.47) and 0.477 mm² (±0.43) described cement voids at the abutment/crown interface; a mean value of 0.062 mm (±0.03), 0.064 mm (±0.35), 0.055 mm (±0.016) and 0.054 mm (±0.024) described marginal gaps. Statistics showed tendency of intraoral cementation to have significantly higher cement remnants compared with abutments with extraoral cementation groups. At the same time, the presence of voids was significantly higher in case of extraoral cementation. No significant differences between groups for the variable "gap".

CONCLUSIONS

Despite the presence of more voids, extraoral cementation reduces cement excess. However, using low adhesivity cement and careful cement removal, a very limited quantity of cement remnants was observed also in the intraoral cementation.