Objective. To evaluate horizontal bone gain and implant survival and complication rates in patients treated with titanium meshes placed simultaneously with dental implants and fixed over them. Methods. Twenty-five patients treated with 40 implants and simultaneous guided bone regeneration with titanium meshes (i–Gen®, MegaGen, Gyeongbuk, Republic of Korea) were selected for inclusion in the present retrospective multicenter study. Primary outcomes were horizontal bone gain and implant survival; secondary outcomes were biological and prosthetic complications. Results. After the removal of titanium meshes, the CBCT evaluation revealed a mean horizontal bone gain of 3.67 mm (±0.89). The most frequent complications were mild postoperative edema (12/25 patients: 48%) and discomfort after surgery (10/25 patients: 40%); these complications were resolved within one week. Titanium mesh exposure occurred in 6 patients (6/25 : 24%): one of these suffered partial loss of the graft and another experienced complete graft loss and implant failure. An implant survival rate of 97.5% (implant-based) and a peri-implant marginal bone loss of 0.43 mm (±0.15) were recorded after 1 year. Conclusions. The horizontal ridge reconstruction with titanium meshes placed simultaneously with dental implants achieved predictable satisfactory results. Prospective randomized controlled trials on a larger sample of patients are required to validate these positive outcomes.

SUMMARY:The controlled free radical polymerization of styrene initiated with benzoyl peroxide (BPO) in the presence of 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (4-oxo-TEMPO) as well as 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl (4-acetamido-TEMPO) at 135 8C was studied. The obtained results were compared with those of the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) controlled free radical polymerization of styrene. Up to a nitroxide/BPO molar ratio of 1.5 : 1, the conversions in the 4-oxo-TEMPO/BPO-system are higher than the conversions in the other systems. The conversion in the 4-acetamido-TEMPO/BPOsystem is lower than that in the 4-oxo-TEMPO/BPO-system, but higher than the conversion in the TEMPO/ BPO-system under the same reaction conditions. The shortest induction periods were observed in the 4-oxo-TEMPO/BPO-system, while the longest induction periods were observed in the TEMPO/BPO-system. Except in the lower region of nitroxide/BPO molar ratio (1 : 1), the number-average molecular weight (M

The bulk polymerization of styrene at 125°C was studied using a [BPO‐polystyrene‐(4‐acetamido‐TEMPO)] macroinitiator synthesized by a styrene polymerization in the presence of 4‐acetamido‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (4‐acetamido‐TEMPO) and benzoyl peroxide (BPO). The rates of polymerization were independent of the initial macroinitiator concentration and they were very similar to that for the thermal autopolymerization of styrene. Additionally, different types of N‐oxyls did not have any effect on the polymerization rate. The number‐average molecular weights (Mn) of the obtained polymers agreed very well with theoretical predictions, deviations were observed only at low macroinitiator concentrations. Increasing macroinitiator concentrations resulted in lower magnitudes of the growing molecular weights and reduced polydispersities (Mw/Mn) at the initial stage of the polymerization. The concentration of the polymer chains was calculated, and it was recognized that the concentration of polymer chains increased during the polymerization as a result of an additional radical formation due to the thermal self‐initiation of styrene. This thermal self‐initiation could be proved qualitatively by the addition of N‐oxyl to a macroinitiator polymerization system.

Through comparative studies on the controlled thermally initiated radical polymerization of styrene in the presence of N‐oxyls, the effect of the type of the N‐oxyls (2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO), 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (OH‐TEMPO), 4‐oxo‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (oxo‐TEMPO) and 4‐acetamido‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (acetamido‐TEMPO)), as well as the concentration of the N‐oxyls (3–20 mmol L–1) are discussed. The radical formation proceeds exclusively through the thermal initiation of styrene, i.e. without using any initiator. It is observed, that the thermal self‐initiation of styrene increases the radical yield remarkably with the N‐oxyls concentration, independent of the type of the N‐oxyl. The concentration‐dependent side reactions of substituted N‐oxyls are remarkably more pronounced than those of unsubstituted N‐oxyl. This leads to the reduction of the overall rate of polymerization (vbr) as compared to TEMPO (vbr = vbr (thermal polymerization)) with respect to the concentration, but independent of the type of substituents.

SUMMARY: Through comparative studies on the controlled thermally initiated radical polymerization of styrene in the presence of N-oxyls, the effect of the type of the N-oxyls (2,2,6,6-tetramethylpiperidine-Noxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (OH-TEMPO), 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (oxo-TEMPO) and 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl (acetamido-TEMPO)), as well as the concentration of the N-oxyls (3 -20 mmol L -1 ) are discussed. The radical formation proceeds exclusively through the thermal initiation of styrene, i.e. without using any initiator. It is observed, that the thermal self-initiation of styrene increases the radical yield remarkably with the N-oxyls concentration, independent of the type of the N-oxyl. The concentration-dependent side reactions of substituted Noxyls are remarkably more pronounced than those of unsubstituted N-oxyl. This leads to the reduction of the overall rate of polymerization (v br ) as compared to TEMPO (v br = v br (thermal polymerization)) with respect to the concentration, but independent of the type of substituents.ZUSAMMENFASSUNG: Durch vergleichende Untersuchungen der kontrollierten thermisch initiierten radikalischen Polymerisation von Styrol in Gegenwart eines N-Oxyls wird der Einfluß der Art des N-Oxyls (2,2,6,6-Tetramethylpiperidin-N-oxyl (TEMPO), 4-Hydroxy-2,2,6,6-tetramethylpiperidin-N-oxyl (OH-TEMPO), 4-Oxo-2,2,6,6-tetramethylpiperidin-N-oxyl (Oxo-TEMPO), 4-Acetamido-2,2,6,6-tetramethylpiperidin-N-oxyl (Acetamido-TEMPO)) und der Konzentration des N-Oxyls (3 -20 mmol L -1 ) diskutiert. Die Radikalbildung erfolgt ausschließlich durch die thermische Initiierung von Styrol, also ohne Zusatz eines Initiators. Beobachtet wird eine wesentliche Erhöhung der Radikalausbeute der thermischen Selbstinitiierung von Styrol in Abhängigkeit von der Konzentration des N-Oxyls, unabhängig von der Art des N-Oxyls. Die konzentrationsabhängigen Nebenreaktionen substituierter N-Oxyle sind wesentlich ausgeprägter. Das führt zur Reduzierung der Bruttopolymerisationsgeschwindigkeit (v br ) im Vergleich zu TEMPO (v br = v br (thermische Polymerisation)) in Abhängigkeit von der Konzentration, aber unabhängig von der Art der Substituenten.