Five years clinical and radiographic evaluation of dimensional changes in peri-implant tissues of Straumann® Roxolid® bone level implants

Abstract

Natural consequences of tooth extraction such as bone resorption and migration of the adjacent tooth create narrow mesio-distal edentulous spaces and mild Seibert Class I defects which can be challenging scenarios for clinicians. The decision of placing narrow-diameter implants with a flapped or flapless surgical technique has not been closely examined in the literature. Since NDIs have reduced contact areas with the bone in comparison with regular diameter implants, titanium alloys with higher tensile and yield strength have been used to manufacture NDIs. A titanium-zirconium (Ti-Zr) alloy has been developed (Roxolid®; Institut Straumann AG, Basel, Switzerland) from 83-87% titanium alloyed with 13-17% of zirconium. The combination of faster osseointegration with higher mechanical strength may allow implants made form Ti-Zr alloy be used in more daring clinical situations. Aim: The primary objective of this non-interventional prospective study is the evaluation of the radiographic bone level changes of Straumann® Roxolid® 3.3 bone level implants from loading to 5 years of follow-up. Secondary objectives include the determination of survival and success rate at 5 years of follow-up and assess, by quantitative 3D analysis, peri-implant soft tissue changes around reduced diameter TiZr Bone Level implants placed in crests with moderate facial resorption reconstructed using the roll flap technique 5 years after surgery. Material and Methods: Twenty patients with unitary or multiple edentulous gaps in the upper and lower jaw without need for vertical augmentation procedures were recruited between October 2009 and May 2010. Implant placement surgery was performed to install Straumann® Roxolid Bone Level implants with 3.3mm diameter. Definitive cemented restorations were placed after a minimum transmucosal healing period of 6 weeks. Follow-up appointment was scheduled 5 years after surgery. Patients who had completed the main study were invited to participate in the follow-up study. Eligible patients were required to attend a routine follow-up appointment for standard oral hygiene procedures, clinical evaluation of the rehabilitation and periapical radiographic examination. Dental casts of ten patients with unitary edentulous gaps in the maxilla (FDI positions 15 to 25) with moderate horizontal facial resorption of the residual ridge and no need for vertical augmentation procedures were 3D examined. Results: At 5 years, 17 of the 20 patients came in for the 5 years follow-up appointment. With a total of 25 out of 29 implants, retrieving a recall rate of 85% at the patient level and 86.2% at the implant level. Mean age of the controlled patients was 48 years old. The overall mean bone level variation from loading to 5 years (mesial and distal) was -0.07 ± 0.78mm. No correlation could be established between bone level changes and labial profile variation. Conclusions: Biomechanically the performance is excellent with survival rate of 100% which can be assigned to the mechanical properties of TiZr alloy associated with its biocompatibility. Narrow-diameter Ti-Zr implants performed well and without restrictions even in lower bone availability situations such as narrow crests over a 5-year period. Even though in our study no correlation could be established between bone level changes and labial profile, hard and soft tissues around reduced diameter TiZr Bone Level implants remained stable during the follow-up period of 5 years.