Interaction of titanium, zirconia and lithium disilicate with peri-implant soft tissue: study protocol for a randomized controlled trial.

BACKGROUND: Against the background of increasing use of dental implants, and thus an increasing prevalence of implant-associated complications, a deeper understanding of the biomolecular mechanisms in the peri-implant tissue is needed. Peri-implant soft tissue is in direct contact with transmucosal dental implant abutments. The aim of this trial is to distinguish the biomolecular and histological interactions of various dental abutment materials with peri-implant soft tissue. METHODS/DESIGN: The study is designed as a prospective, randomized, investigator-initiated clinical pilot trial with blinded assessment. We will ultimately include 24 eligible patients who opt for implant treatment to replace a single missing posterior tooth. Three months after implantation (submerged procedure), the study begins with the second-stage surgery. Each of the 24 patients will be given three different transmucosal abutments (zirconia, lithium disilicate, titanium) consecutively. The sequence in which the three materials are used is randomized. Peri-implant crevicular fluid is sampled weekly around the respective abutment for biomolecular analyses. After one month of wearing time, the stamping press from the second-stage surgery is used to gain a narrow gingival ring biopsy around the abutment for immunohistochemical analyses. The next abutment is then inserted. The same procedure is used for all three abutments. After sampling is completed, the patients will receive a definitive crown. The primary outcome measure of the trial is biomolecular detection of specific markers in the peri-implant crevicular fluid: matrix metalloproteinase 8, interleukin- 1ß, polymorphonuclear elastase, and myeloid-related protein MRP8/14 (calprotectin). Secondary outcome measures include immunohistochemical analyses and clinical parameters. DISCUSSION: The study design will allow us to perform correlation analyses between the clinical indices with biomarkers' expression in the interface of the transmucosal abutments and the peri-implant soft tissue. A deeper understanding of the three abutment materials' interactions with peri-implant soft tissue will help us understand the formation mechanisms of implant-associated complications and then develop prevention strategies. TRIAL REGISTRATION: The trial is registered at the German Clinical Trial Register and the International Clinical Trials Registry Platform by the WHO under DRKS00006555 (Registered on 27 October 2014).

PDT with TOOKAD(®) studied in the chorioallantoic membrane of fertilized eggs.

BACKGROUND: The potential application of TOOKAD(®)-PDT for the treatment of blood vessels was investigated. TOOKAD(®) (WST09), a novel palladium-bacteriopheophorbide absorbs light in the near IR with a high quantum yield of intersystem crossing. Our study assessed the efficacy of this drug in inducing vascular damage with a view to its possible use in the treatment of age-related macular degeneration. METHODS: Vascular damage of TOOKAD(®)-PDT was studied in neovessels of the chorioallantoic membrane of fertilized eggs. Pharmacokinetic investigations were done by video microscopy and laser scanning microscopy. To induce damage vessels were irradiated with 763nm light from a diode laser. RESULTS: TOOKAD(®) was accumulated in the vessels in the first minutes following injection. TOOKAD(®) fluorescence was seen predominantly in the lumen and not in the vascular endothelial layer. Although fluorescence was very weak it could be attributed to TOOKAD(®) from the fluorescence spectrum in the circulation. Damage assessment was done 24h after application of 763nm light. No significant difference in the degree of damage was observed with different short drug-light intervals (1-10min), but damage increased with the light energy dose. Closure of smaller vessels and vanished capillaries could be achieved by irradiation with 5J/cm(2) and a TOOKAD(®) dose of 33µg/embryo, corresponding to a phototoxic efficacy of 0.0062. CONCLUSIONS: From the results discussed in this work, TOOKAD(®) could be a potential drug for the PDT of age-related macular degeneration in which the growth of new vessels in the choroids can lead to loss of vision.