Bücher und Digitale Medien

Purpose: to measure the surface temperature distribution after CO2-laser heating of titanium dental implants using different power settings, application intervals and irradiation times. Materials and methods: 10 tissue-level-type titanium implants (Camlog Screw-line Promote Plus 4.3mm x 11mm) were embedded (Epofix, Struers ApS, Copenhagen, Denmark) and irradiated with a carbon-dioxide-laser (Denta II, Lutronic Corporation, Fremont, USA) with a wavelength of 10.6µm and at power levels of 4watts (group 1), 6watts (group 2), 8watts (group 3) and 10watts (group 4). A continuous beam mode (setting I) and non-continuous beam modes with 5second (setting II) and 10second (setting III) pause intervals were used. For each setting, a total irradiation time of 50seconds was used and repeated 10 times. The temperature was measured using external thermocouples (Testo SE & Co. KGaA, Lenzkirch, Germany) in contact with the implant surface at implant shoulder, middle and apex. A linear regression model was used to analyse the data (p = 0.05). Results:  Setting I demonstrated the most rapid increase in implant surface temperature in all three test sites as well as the greatest total temperature at 50 seconds of irradiation time. The greater the pause interval (settings II and III) during the 50 seconds of irradiation, the lower the rate of temperature increase as well as the total temperature in all three test sites and with all power levels. The average temperature difference between the apex and shoulder site was significant for test setting III for all groups, but not for any groups in settings I and II. Conclusion: Heating the internal aspect of a dental implant with a CO2-laser produces different temperature distribution profiles depending on the laser power level and the application interval. Laser-beam irradiation leads to a temperature gradient which is greatest at the implant apex and smallest at the implant shoulder. 

Purpose: To evaluate the accuracy of complete-arch digital implant impressions using different intraoral scan body (ISB) materials and intraoral scanners (IOSs). Materials and Methods: The mandibular dental cast of an edentulous patient with six tissue-level dental implants was used as master cast. Two types of ISBs, polyether-ether-ketone (PEEK) and plasma-coated medical titanium, were used with five IOSs: TRIOS 4 (T4), Virtuo Vivo (VV), Medit i700 (Mi700), iTero5D (i5D), and Primescan (PS). To assess accuracy, digital impressions (n=10) with each IOS and ISB were compared to two reference models obtained by digitizing the master cast with each ISB type using a desktop scanner (IScan4D LS3i) and importing the scan data into metrology software (Geomagic Control X). Root-mean-square (RMS) error was employed to evaluate overall deviation values (trueness), while precision was determined using the standard deviation (SD) of RMS values. Statistical significance was set at P < 0.05. The Kruskal-Wallis test was used, followed by the pairwise comparison method with Bonferroni correction (α=.05). Results: An interaction between ISB material and IOS was found (P=0.001). Plasma-coated medical titanium ISBs demonstrated significantly higher trueness and precision compared to PEEK ISBs with T4 (P=0.001), Mi700 (P=0.001; P=0.004), and i5D (P=0.001). Conversely, VV exhibited higher trueness and precision values with PEEK ISBs (P=0.005; P=0.003). PS provided the highest trueness and precision regardless of the ISB material (P=0.912). T4 showed the lowest accuracy for PEEK ISBs, and VV for plasma-coated medical titanium ISBs. Conclusion: Except for PS, all IOSs showed significant differences between ISB materials. PS demonstrated the highest accuracy with both ISB materials, whereas T4 had the lowest accuracy for PEEK ISBs, and VV showed the lowest accuracy for plasma-coated medical titanium ISBs.

Purpose: To assess the influence of the bonding system and restorative material on the marginal integrity and pull-off forces of monolithic all-ceramic crowns bonded to titanium base (ti-base) abutments. Materials and Methods: A total of 108 ti-bases were sandblasted and divided into nine experimental groups (n = 12) according to the combination of crown material (polymer-infiltrated ceramic-network [PI], lithium-disilicate [LD], and zirconia [ZI]) and bonding system (Multilink Hybrid-Abutment [MH], Panavia V5 [PV], RelyX Ul5mate [RU]) with the respective primers. After bonding the crowns to the ti-base abutments, the restorations were screw-retained on implants and thermomechanically aged (1,200,000 cycles, 49 N, 1.67 Hz, 5 to 55°C). Marginal integrity and bonding failures were evaluated under a light microscope, and pull-off forces (N) were calculated. Chi-square tests for marginal integrity as well as one-way and two-way ANOVA statistical tests for pull-off forces were applied (a = .05). Results: PI presented higher marginal integrity than LD (P = .023). Bonding system PV revealed higher marginal integrity than MH (P =.005) and RU (P =.029). Differences in pull-off forces were found between restorative material and resin cements (P < .001), with the highest values for ZI + RU (598 ± 192 N), PI + PV (545 ± 114 N), LD + MH (532 ± 116 N), and PI + RU (528 ± 81 N). Specimens with marginal integrity revealed higher pull-off forces than those with alteration (P = .006). Specimens presenting bonding failures (micromovements) showed lower pull-off forces than those without bonding failures (P < .001). Conclusions: The tested CAD/CAM materials show favorable bonding performances with different bonding systems, nevertheless for each restorative material a specific bonding system has to be recommended. Int J Prosthodont 2023;36:e88–e102