Cement Excess at Single Implant Crowns Malmö/Lund

Clinical, Microbiological and Histological Effects of Cemented Implant Restorations. A Cross-over Controlled Clinical Study

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.

Patients in group A will receive a screw-retained implant crown. Following this first period of 16 weeks, the screw-retained implant crown will be replaced by a new intraorally cemented implant crown. Cement removal will be preformed according to best clinical procedure. These implant 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 implant crowns will be removed to evaluate any excess cement. All patients will be fitted with the original screw-retained implant crown. Clinical parameters for inflammation and probing depths will be obtained after each 16 week-period.

In group B the implant crowns will be incorporated in a reverse pattern. During the first 16 weeks a cemented implant crown will be inserted and 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 implant 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.

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.

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.

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.

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.

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).

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).

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)

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)

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)

The collected microbiological samples will additionally be analyzed for two host markers (MMP8, IL-1ß) that will be determined by ELISA.

The collected microbiological samples will additionally be analyzed for two host markers (MMP8, IL-1ß) that will be determined by ELISA.

A single-tooth x-ray will be obtained at the time of implant placement and again at abutment connection in order to ensure sufficient osseointegration of the implant before entering the prosthetic phase. At the time of insertion of the respective reconstruction in both groups, another periapical radiograph will be obtained to ensure the fit of the reconstruction and to check for eventual cement residue. A final x-ray will be taken at insertion of the final screw-retained implant crown to serve as baseline regarding marginal bone level at the time of final crown insertion.

Inclusion Criteria: - patient older than 18 years systemically healthy subject periodontally healthy individuals absence of peri-implantitis no bone loss good oral hygiene (PCR ≤ 20%) healthy periodontal tissues (BoP≤ 20%) patients with a single tooth gap in the posterior area of either jaw (premolars and molars) at least 8mm in mandible; at least 6mm in maxilla (summers technique) Exclusion Criteria: - ongoing periodontal disease bruxism unwilling to comply with study procedures heavy smokers (≥10 cig/d) ongoing periodontitis/implantitis

the scans of the sealed randomization envelopes will be sent to the center in Lund, Sweden whenever a patient is included and ready to take the impression. A folder structure on switch drive is set up with the Subject numbers (1-24) in order to upload the CRFs, photographs and X rays.