Comparison of the Bond Strength of Composite Resin to Zirconia and Composite Resin to Polyether Ether Ketone: An In Vitro Study.

AIM: The aim of the study was to compare the shear bond strength of composite resin bonded to polyether ether ketone (PEEK) and zirconia, and also to evaluate the effect of thermocycling on the shear bond strength. MATERIALS AND METHODS: A total of 22 zirconia (Group 1) and 22 PEEK (Group 2) specimens (disks of 10 mm in diameter and 10 mm in thickness) were machine milled using computer-aided design (CAD)/computer-aided manufacturing (CAM) from commercially available zirconia and PEEK. These specimens were air abraded with 110-µm aluminum oxide. Following which these two groups were subdivided into four groups, that is, Group 1A: 11 zirconia specimens before thermocycling, Group 1B: 11 zirconia specimens after thermocycling, Group 2A: 11 PEEK specimens before thermocycling, and Group 2B: 11 PEEK specimens after thermocycling. These four groups of specimens were embedded in an acrylic block, and bonding agent was applied over the upper surfaces of the disks of each of these specimens. Composite resin was then cured, and then Group 1B and group 2B were thermocycled under a standard temperature. The bond strength of the specimen was tested using universal testing machine. RESULT: The result showed that there was no significant difference in shear bond strength between the groups, although higher shear bond strength was observed in the PEEK group. CONCLUSION: Shear bond strength of PEEK is similar to zirconia. The results suggest that the pretreatment method and primers used were effective in improving the bonding of resin cements to zirconia ceramic and the bonding properties of the veneering resin to the PEEK surface.

An in vitro study to compare the influence of newer luting cements on retention of cement-retained implant-supported prosthesis.

PURPOSE: The study was conducted to evaluate the retentiveness of specifically formulated implant cements and compare its retentiveness with a commonly used noneugenol zinc oxide luting cement and also to assess the influence of abutment height on the retentiveness of these cements. MATERIALS AND METHODS: A master stainless steel mold was used to mount snappy abutment-implant analog complex in acrylic resin. A total of six snappy abutments (Nobel Biocare®) of 4 mm and 5.5 mm height with their analogs were used. A total of 66 ceramill® Sintron metal copings fabricated using computer-aided design/computer-aided manufacturing system and divided into six groups (n = 11) according to the height (three 4 mm abutment and three 5.5 mm abutment). The cements that were compared were a Noneugenol zinc oxide provisional cement (Temp-Bond™ NE), a Noneugenol temporary resin cement (Premier® Implant Cement) and a resin based acrylic urethane cement (Implalute® Implant Cement). After cementation samples were immersed in artificial saliva for 7 days and subjected to a pull-out test using a universal testing machine at a crosshead speed of 1 mm/min. The load required to de-cement each coping was recorded and analyzed using one-way ANOVA, post hoc multiple comparison, and independent t-test. RESULTS: Noneugenol temporary resin cement had the highest tensile strength followed by noneugenol zinc oxide cement and the least retentive strength was observed in resin-based acrylic urethane cement. CONCLUSION: The results suggest that noneugenol temporary resin cement may be considered as a better choice for cementation of implant prosthesis, as it has shown to have better mechanical properties.

Study to assess the relationship between insertion torque value and implant stability quotient and its influence on timing of functional implant loading.

PURPOSE: One of the crucial requirements for the success of implants is to achieve good stability. Two well-accepted quantitative methods to assess implant stability, the insertion torque value (ITV), and resonance frequency analysis (RFA) can be a valuable adjunct to radiological and clinical examination. This study was conducted to assess the relationship between ITVs and implant stability quotient (ISQ) and its influence on timing of functional implant loading, as well as to determine the effect of some of the factors on the stability of implants. MATERIALS AND METHODS: Forty implants were inserted in 37 patients in the posterior mandibular region according to conventional protocol and allowed to heal by placing a healing abutment at the time of placement. For each implant, ITV was measured at the time of the implant placement by manual torque wrench (Nobel Biocare), and the ISQ value was measured by using resonance frequency analyzer (Osstell-ISQ; Integration Diagnostics) at the baseline levels, 3rd week, 7th week, 11th week, and 15th week interval. RESULTS: The correlation between ITV and ISQ was found to be moderately positive and significant (r = 0.399) (P = 0.000). The correlation of ITV value at baseline and ISQ values recorded at the subsequent weeks was also found to be statistically significant at week 3 (r = 0.376) (P = 0.000) and week 7 (r = 0.327) (P = 0.000). CONCLUSION: It can be concluded from this study that there is a positive and statistically significant correlation between the ITV and ISQ values.

A three-dimensional finite element analysis of a passive and friction fit implant abutment interface and the influence of occlusal table dimension on the stress distribution pattern on the implant and surrounding bone.

AIMS: The aim of the study was to evaluate the stress distribution pattern in the implant and the surrounding bone for a passive and a friction fit implant abutment interface and to analyze the influence of occlusal table dimension on the stress generated. MATERIALS AND METHODS: CAD models of two different types of implant abutment connections, the passive fit or the slip-fit represented by the Nobel Replace Tri-lobe connection and the friction fit or active fit represented by the Nobel active conical connection were made. The stress distribution pattern was studied at different occlusal dimension. Six models were constructed in PRO-ENGINEER 05 of the two implant abutment connection for three different occlusal dimensions each. The implant and abutment complex was placed in cortical and cancellous bone modeled using a computed tomography scan. This complex was subjected to a force of 100 N in the axial and oblique direction. The amount of stress and the pattern of stress generated were recorded on a color scale using ANSYS 13 software. RESULTS: The results showed that overall maximum Von Misses stress on the bone is significantly less for friction fit than the passive fit in any loading conditions stresses on the implant were significantly higher for the friction fit than the passive fit. The narrow occlusal table models generated the least amount of stress on the implant abutment interface. CONCLUSION: It can thus be concluded that the conical connection distributes more stress to the implant body and dissipates less stress to the surrounding bone. A narrow occlusal table considerably reduces the occlusal overload.