Long Term Comparison of Ultrasonic and Hand Instrumentation in the Maintenance of Peri-implant Tissues: A Randomized Clinical Trial

Long term comparison of ultrasonic and hand instrumentation in the maintenance of peri-implant tissues: A randomized clinical trial

Objective

The aim of this study is to determine the clinical effects, presence of inflammatory cytokines, and the patients' perceived discomfort by comparing titanium scalers to ultrasonic instrumentation using implant inserts in a patient population with healthy peri-implant tissues and implants with peri-implant mucositis during a one-year period of peri-implant maintenance.

Hypothesis

There are insufficient studies in the literature to guide the clinician which technique will offer better results in maintaining health or in decreasing inflammation long term around dental implants during peri-implant maintenance. It is postulated in this study that (1) peri-implant therapy will have a beneficial clinical effect, will decrease the presence of inflammatory cytokines and will be well tolerated by the patient population and that (2) there will be no differences in the outcomes between the two peri-implant maintenance therapies.

Materials and Methods

Previous approval by the Biomedical Research Ethics Board of the University of Manitoba a randomized clinical trial will be conducted between May, 2014 and May, 2015 at the Periodontics Clinic of the University of Manitoba. The Oral Biology Laboratory of the University of Manitoba will perform the analysis of samples of the peri-implant crevicular fluid. The Consolidated Standards of Reporting Trials, CONSORT Statement will be followed.

66 participants with at least one single dental implant will be recruited and randomly assigned to one of the two peri-implant maintenance groups. Subjects enrolled in the study will be regular patients of the Periodontics Graduated Clinic at the University of Manitoba, Faculty of Dentistry. Each participant will sign a written informed consent. The randomization will be computer-generated by a second person not involved in the study.

A total of 352 sites (6sites/implant) will be studied. Cohen effect size has been used to calculate the sample size. Small to medium effect size ranges by Cohen: 0.2mm to 0.5mm. In addition, independent t-test with alpha=0.05, power (1-beta) =80%, 95% confidence interval and two tailed test. Allocation ratio, n1/n2=1. G*Power 3.1.7 software was used in sample size calculation. An attrition rate of 6 participants was calculated.

A code will be assigned to each participant. Only the research coordinator will have access to the patients/codes matching list and its corresponding therapy. The peri-implant maintenance will be performed by two experienced Dental Hygienists previous intra and inter-examiner calibration. A single blinded calibrated examiner (MC) will do the recording of clinical findings and sampling at baseline, 3, 6 and 12 months.

The following are the inclusion criteria: (1) subjects having at least one single unit dental implant (2) probing depths no more than 5mm in 6 aspects around each implant (MB, B, DB, ML, L and DL), (3) no bone loss beyond 2mm/implant at baseline confirmed with periapical radiographs with a cone paralleling technique. The next criteria will be excluded from the study: (1) implant supported removable prostheses, (2) use of antibiotics within the preceding 3 months (3) smokers (4) missing exam at baseline.

The parameters to be assessed at 6 sites/implant are the following: (1) Modified plaque index by Mombelli (2) Modified gingival index by Mombelli, (3) probing depths (PD), (4) presence of keratinized gingiva (0, 0.5-1.5mm, 2 or greater), (5) recession (REC) distance between gingival margin and most occlusal point of restoration, (6) Cytokine levels in peri-implant crevicular fluid, 1 sample from the deepest site of implant(s) will be collected at baseline, 3, 6 and 12 months. In addition, patients will also be asked to fill in a pain questionnaire at the end of the study period (Visual analogue scale, VAS).

To collect the peri-implant crevicular fluid, the site will be isolated from saliva using cotton rolls and drying before the sampling. Periopaper strips (Oraflow) will be introduced at the deepest site of the implant sulcus for 30 sec. The volume of peri-implant crevicular fluid will be measured using a Periotron. Until further analysis strips will be store at -80C in sealed plastic tubes previously identified with a code corresponding to the name of the patient. Pro-inflammatory/pleiotropic cytokines, which are found during inflammatory processes at cellular level will be assess. The fluorescence based multiplex protein quantification system (BioPlex, BioRad, Hercules CA, USA) will be used to measure the following eight cytokines: GM-CSF, IFN-gamma, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α.

Ethical Considerations

The patients will be asked to review and sign a written consent form. Only individuals involved in this study will have access to the data collected during the study. The records for each patient will be assigned with a unique number and will be stored by the principal investigator at her desk within the clinic premises. The master sheet linking the patient identifiers to the unique number will be stored in a safe in the clinic administrative office. In case of possible continuation of line of investigation, the data could be compared with new data (introduction of air abrasive). The master sheet and patient records will be shredded at the end of 4-5 years. To thank them for their participation in the study they will receive a free maintenance appointment at the end of the study (12 months).

Relevance of the study

This study is relevant because there is currently no long term in vivo studies that determine the effectiveness of peri-implant maintenance and also the possible differences and/or similar outcomes between curettes and ultrasonics in the peri-implant maintenance protocol.