Effect of different localizations of microgap on clinical parameters and inflammatory cytokines in peri-implant crevicular fluid: a prospective comparative study.

The purpose of this study was to evaluate the effect of microgap on clinical and biochemical parameters around dental implants for 1 year. All patients received four implants: group A-Standard Straumann(®) implants, group B-1 mm subcrestal placement of the polished surface of group A implants, group C-esthetic plus Straumann® implants, group D-subcrestal placement of the polished surface of group C implants. Clinical measurements and peri-implant crevicular fluid (PICF) were collected immediately before loading and at 3rd, 6th, and 12th months after loading, and interleukin-1 beta (IL-1ß) and tumor necrosis factor-alpha (TNF-α) have been assessed in the crevicular fluid. No significant differences were found in plaque index, gingival index, and probing between the groups throughout the study. However, the PICF volumes of group D were significantly higher than that in the other groups, and group A were significantly lower than the other groups (P < 0.05). With respect to bleeding on probing values, the percentage of BOP (+) sides in group A implants were fewer than group C and D implants (P < 0.05). With regard to IL-1ß, the levels of IL-1ß in group A were lower than that in the other groups during the study (P < 0.05). In point of TNF-α total amounts, the levels of TNF-α in group A implants were lower than those in group B and D implants (P < 0.05). Moving microgap coronally from alveolar crest could be recommended for the health of periodontal tissues. Most coronal location of microgap can be suggested in order to maintain the peri-implant health status, particularly in implant sites without esthetic priority.

Bacterial adhesion and colonization differences between zirconium oxide and titanium alloys: an in vivo human study.

PURPOSE: The purpose of this study was to compare zirconium oxide and titanium alloys with respect to their tendency to adhesion and colonization of two periodontal pathogens on both hard surfaces and on soft tissues in vivo. MATERIALS AND METHODS: The present study was designed as a prospective stratified randomized controlled clinical trial. Patients were scheduled to receive two implants with different types of abutments in the posterior mandible. Three months after implant placement, titanium and zirconium abutments were connected. Five weeks after abutment connections, the abutments were removed, probing depth measurements were recorded, and gingival biopsy samples were obtained. Abutments and biopsy specimens were analyzed by reverse-transcriptase polymerase chain reaction to compare the DNA copy numbers of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and total bacteria. The surface free energy of the abutments was calculated by sesile water drop before replacement. RESULTS: No statistically significant differences were found between probing depths or DNA copy numbers of A actinomycetemcomitans, P gingivalis, and total bacteria both for both titanium alloys and zirconium oxide surfaces and the biops specimens obtained from their buccal gingival. With respect to the surface free energy of zirconium and titanium abutments, zirconium abutments showed lower surface free energy than titanium abutments. CONCLUSION: The results of this study showed that zirconium oxide surfaces have comparable properties to titanium alloy surfaces in their tendency to adhesion and colonization of two periodontal pathogens on both hard surfaces and in soft tissues.