Comparison Between Two Different Tissue-Level Implant Systems: A Prospective Clinical Study

The objective of this prospective study is to compare clinically and radiographically two different tissue-level implants, in partially edentulous patients in the posterior area of the maxilla and mandible. The primary objective of the study was to track the crestal bone level changes around the two implant systems. Secondary objectives were implant stability as well as initial soft tissue thickness which were evaluated throughout this study.

The study is designed as a prospective clinical trial with a parallel design comparing two different tissue-level implants placed adjacently in the posterior maxilla and mandible. The primary outcome is the change in the interproximal crestal bone level.

Patients in this study were recruited from the general population attending the department of Periodontology at the Saint-Joseph University. Adult patients (males and females) in need of implant rehabilitation for partial edentulism in the posterior maxilla and mandible have been selected to take part in this study. Following initial screening procedures, each patient underwent a site-specific intraoral and radiographic examination (Cone Beam Computed Tomography analysis and periapical radiographs) in order to make sure that the inclusion criteria were satisfied. Patients presenting with bone width of less than 6 mm or more than 9 mm were immediately excluded from the study. The day of the surgery, each implantation site was given a number depending on the tooth missing. Then, using a random team generator software each site was randomly assigned to one of the two groups based on the implant system used:

The first group (group 1) consisted of patients receiving Straumann Standard Plus (SP) implants of 4.1 mm in diameter and length of 10 mm.

The second group (group 2) included patients receiving JD Octa implants of 4.3 mm in diameter and 10 mm in length.

Participants were blinded as to the assignment in the first or second group. The implant placement procedures were planned based on clinical and radiographic evaluation.

The following parameters were monitored for each case:

Crestal bone level changes (CBL)

Primary and secondary implant stability

Initial soft tissue thickness

After a healing time of 3 months Patients were recalled 6 and 12 months after prosthetic treatment. At each visit, the restorations were evaluated for mobility, oral hygiene, peri-implant soft tissue conditions and patient satisfaction. Intraoral standardized radiographs were also taken at the 12-months follow-up visit to evaluate crestal bone level changes. CBL changes were defined as the difference between two consecutive CBL measurements. Secondary implant stability was evaluated. Impressions were taken at the implant level. Abutments were fixed on the implants with titanium screws.

In order to reduce the risk of bias in the study, all the implant-supported crowns were screw retained. However, in only one case, and due to prosthetic considerations, two implant-supported crowns were cemented using a temporary cement. In this case, the restorations were thoroughly checked for excessive cement.

Final restorations were delivered within 2 weeks of referral. Finally, standardized radiographs were taken to ensure abutment seating and check for residual cement (in the case of cemented crowns).

Patients were recalled 6 and 12 months after prosthetic treatment. At each visit, the restorations were evaluated for mobility, oral hygiene, peri-implant soft tissue conditions and patient satisfaction. Intraoral standardized radiographs were also taken at the 12-months follow-up visit to evaluate crestal bone level changes. As described previously, CBL changes were defined as the difference between two consecutive CBL measurements.

Eligibility Criteria:
Inclusion Criteria:

* Patients over the age of 18, requiring placement of at least two adjacent implants in the posterior maxilla or mandible (premolar-molar area)
* Patients willing to sign the consent form and respect the follow-up period of the study
* Non-smokers or light smokers (less than 10 cig/day)
* No bone augmentation procedures before or during implant placement in the area of interest
* Healthy soft tissue conditions (full mouth plaque scores \< 20% and full mouth bleeding index \< 20%)
* Minimum height of 2 mm of keratinized tissue
* Minimum of 6 mm in bone width and 10 mm in bone height
* Minimal distance of 2 mm between predicted implant tip and inferior alveolar nerve
* Healed sockets (at least 4 months post-extraction)

Exclusion Criteria:

* Patients not satisfying the inclusion criteria
* Patients with any local or systemic disease
* Patients taking any kind of medication that interferes with bone metabolism
* Pregnant or breast-feeding women
* Patients with parafunctional disorders
* Patients with poor oral hygiene
* Heavy smokers (\>10 cig/day)