Influences of Different Torques on the Size of the Microgap and Bacterial Leakage in Different Implant Systems: An In-vitro Study.

PURPOSE: To evaluate the adherence of three types of bacteria [Staphylococcus (S) aureus, Escherichia (E) coli, Pseudomonas (Ps) aeruginosa] and the size of the microgap of three different implant systems (JD, ORA, and Ankylos) under four different screw torque values. MATERIALS AND METHODS: Ten samples for each tested implant system were used under different torques to determine the width of the gaps. The abutments were connected to the fixtures using a universal digital wrench. A torque value of 10 N/cm was applied for all samples. After the assessment of the microgap, the fixture was repositioned into the Bench Vice, and the torque was increased to 20, 30, and, finally, 40 N/cm. The microgap assessment was done using a Scanning Electron Microscope. Before the torque increased to 40, eleven samples for each tested implant system were used under 30 N/cm torque to determine the leakage in the tested implants for S. aureus, E. coli, and Ps. aeruginosa. Data were analyzed with multiple one-way ANOVA, Post Hoc, and chi-square tests. RESULTS: The Ankylos system showed the widest gap under all torques (p < 0.005), whereas the JD system demonstrated the lowest (p < 0.005). Regarding the bacteria leakage, JD showed the highest adherence to the bacteria, and the adherence was mainly to the Ps. Aeruginosa, while the Ankylos system showed the lowest (p < 0.005). CONCLUSION: Within limits, the higher torque provides a higher fit to the IAI, offering more stability. Ankylos implant showed the widest gap, while JD showed the narrowest. Regarding the bacteria leakage, JD showed the highest adherence to Ps. Aeruginosa, while the ORA system showed the highest adherence to E. coli.

Maximum bite force following unilateral fixed prosthetic treatment: a within-subject comparison to the dentate side

We evaluated the maximum occlusal bite force [MBF] among individuals with fixed partial dentures compared to the opposite dentate side and determined the relationship between MBF and gender, age, and body mass index [BMI]. Subjects and A total of 85 subjects [43 males and 42 females, age range 28-66 years] with fixed partial dentures on one side and dentate on the other side participated in the study. The MBF was measured at the first molar area on both sides using a digital hydraulic bite force gauge. The highest MBF value was recorded from three measurements of bite force at each side [with 45-second intervals between measurements]. The mean MBF was 596.2 +/- 76.3 N at the dentate side and 580.9 +/- 74.3 N at the fixed partial denture side. The difference was statistically significant [p < 0.05]. The MBF values were greater in males as well as in taller and heavier participants. Nevertheless, the BMI had no relationship with MBF values [p >0.05]. Within the same subjects, the measured MBF values at the dentate side were higher than those at the fixed partial denture side. Females, lighter, and shorter participants had lower MBF values. Meanwhile, the BMI had no significant relationship to MBF values

Comparative analysis of dimensional precision in different silicone impression materials

The polyvinyl siloxane impression materials are one of the pioneer elastomers that have been introduced to the dental practice many years ago. These materials have gained popularity among dental practitioners as well as patients. The comparison of different commercial types for the same impression material was not thoroughly studied and therefore needs further investigation. This study was prompted to investigate the accuracy of four commercial types of additional silicone impression materials. These types namely the AFFINIS[registered], Virtual[registered], Relay 2002 CD[registered] and Silagum[registered]. The accuracy of impression material was measured indirectly by measuring three dimensions on stone cast poured from impressions of a stainless steel master model. The three dimensions on stone cast were measured at one hour, two days, one week and two weeks alter making the impression. Two impression techniques were used in the current study. The two-steps impression technique was used for AFFINIS[registered] and Virtual[registered], while single-step technique was used for Relay 2002 CD[registered] and Silagum[registered] materials. Twenty impressions were made of the master cast at four different periods for each of the tested four materials, with a total of 320 impressions. Two vertical dimensions and one horizontal dimension were measured on master cast using optical microscope [Titan, USA] to 0.001 mm rounding up magnification. Statistical analysis was run to compare the mean measurements for tested casts from each impression and time interval with the master cast, no statistical significant differences were found, thus, under the condition of this study, the time factor has no effect on the accuracy of tested impression materials up to four weeks duration. There was no significant difference of master cast means and impression cast means over time. Additionally, impression technique could be correlated with accuracy. Finally, it is concluded that the tested additional silicones showed accuracy over time and they could be delayed up to four weeks duration without any significant changes in its dimensional stability. Meanwhile, Silagum[registered] impression materials were the most accurate materials throughout this study followed by Relay 2002 CD[registered], Virtual[registered] and AFFINIS[registered]. It is recommended to investigate different commercial types of additional silicones neutrally without the effect of manufacturers' propaganda