Abstract Aim: The primary aim of this study is to test whether or not cement residues in the submucosal environment of implants lead to a change in the microbiota and induce inflammation of the periimplant tissues. Material and Methods: 24 patients in need of a single tooth replacement will be enrolled in this cross-over controlled clinical study. All patients will receive a two-piece dental implant, which will be restored with both a cemented and a screw-retained single crown. At the time of impression taking, patients will be randomized into two groups. Patients in group A will receive a screw-retained crown. Every 8 weeks microbiological samples using sterile paper points will be collected and analyzed for bacterial content by real-time PCR. Additionally, two host markers (MMP8, IL-1ß) will be determined by ELISA. Following this first period of 16 weeks, the screw-retained crown will be replaced by a new intraorally cemented crown. Cement removal will be preformed according to best clinical procedure. These crowns will again be left for another period of 16 weeks and followed up for the harvesting of microbiological samples every 8 weeks. After the second 16-week the crowns will be removed to evaluate any excess cement. All patients will be fitted with the original screw-retained crown. Clinical parameters for inflammation and probing depths will be obtained after each 16 week-period. In group B the crowns will be incorporated in a reverse pattern. During the first 16 weeks any possible cement residues will be removed according to best clinical procedure, while for the second period of 16 weeks patients will be fitted with a screw-retained single crown. Again, microbiological and clinical parameters will be obtained at the same intervals as in Group A. After the second 16 week period the screw-retained crowns will be (re-) inserted in all patients, single tooth x-rays taken and clinical baseline values obtained. Additionally, a soft tissue biopsy will be harvested at the time of insertion of the final screw-retained crown. Patients will be followed up for another 16-week period.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
24
After the second 16 week period the screw-retained crowns will be (re-) inserted in all patients, single tooth x-rays taken and clinical baseline values obtained. Additionally, a soft tissue biopsy will be harvested at the time of insertion of the final screw-retained crown. Patients will be followed up for another 16-week period.
Folktandvården Skåne
Lund, Skåne County, Sweden
Analysis of microbiological parameters
Change relative percentage of gram-negative microorganisms
Time frame: Change BL to 16 weeks post-restoration
Histomorphometric analysis
A soft tissue biopsy will be harvested at the time of insertion of the final screw-retained implant crown in all patients. The biopsies will be used for histomorphometric measurements.
Time frame: 32 weeks after BL
Immunohistologic analysis - putative periodontal pathogens
The biopsies will be used for the determination of inflammation and infection markers applying light-microscopy. Gingival crevicular fluid (GCF) will be collected using standardized filter paper strips. A battery of 10 putative periodontal pathogens will be analyzed using real-time PCR.
Time frame: 32 weeks after BL
Immunohistologic analysis - MMP8
The biopsies will be used for the determination of inflammation and infection markers applying light-microscopy. Gingival crevicular fluid (GCF) will be collected using standardized filter paper strips.
Time frame: 32 weeks after BL
Immunohistologic analysis - IL1ß
The biopsies will be used for the determination of inflammation and infection markers applying light-microscopy. Gingival crevicular fluid (GCF) will be collected using standardized filter paper strips.
Time frame: 32 weeks after BL
Analysis of inflammation markers on RNA-basis - (IL-4, IL-3, IL-1alfa, IL-1beta)
Tissue samples will further be processed with a (ribonucleic acid) RNA solution to allow for RNA extraction. This will then be analyzed via polymerase chain reaction (PCR) to determine expression patterns of markers such as Interleukin (IL-4, IL-3, IL-1alfa, IL-1beta) and tumor necrose factor (TNF-alfa).
Time frame: 32 weeks after BL
Analysis of inflammation markers on RNA-basis - TNF-alfa
Tissue samples will further be processed with a (ribonucleic acid) RNA solution to allow for RNA extraction. This will then be analyzed via polymerase chain reaction (PCR) to determine expression patterns of markers such as Interleukin (IL-4, IL-3, IL-1alfa, IL-1beta) and tumor necrose factor (TNF-alfa).
Time frame: 32 weeks after BL
Clinical parameters - Probing Depth
In order to assess the inflammatory status of the peri-implant tissue, different parameters will be assessed: 1) plaque index (dichotomous values) 2) keratinized tissue width (continuous) 3) BOP (dichotomous), 4) PD (continuous), 5) recession (continuous)
Time frame: Every 8 weeks until 48 weeks and again at the 1-year follow-up
Clinical parameters - Bleeding-on-Probing
In order to assess the inflammatory status of the peri-implant tissue, different parameters will be assessed: 1) plaque index (dichotomous values) 2) keratinized tissue width (continuous) 3) BOP (dichotomous), 4) PD (continuous), 5) recession (continuous)
Time frame: Every 8 weeks until 48 weeks and again at the 1-year follow-up
Clinical parameters - Plaque Index
In order to assess the inflammatory status of the peri-implant tissue, different parameters will be assessed: 1) plaque index (dichotomous values) 2) keratinized tissue width (continuous) 3) BOP (dichotomous), 4) PD (continuous), 5) recession (continuous)
Time frame: Every 8 weeks until 48 weeks and again at the 1-year follow-up
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