Originalarbeit englisch - ZZI 03/2014

Immediate occlusal versus non-occlusal loading of implants: a randomized clinical pilot study

M. Lorenzoni1, M. Stopper2, W. A. Wegscheider3, S. Vogl4

Statements of problem: Immediate occlusal and non-occlusal loading protocols have been extensively discussed and, despite varying success rates, are considered viable in selected cases. Preoperative implant planning and intraoperative transfer are essential to the success of implant-supported reconstructions in partially or completely edentulous jaws. We performed this study to compare clinical outcomes of immediate occlusal versus non-occlusal loading of posterior implants.

Materials and methods: Of 20 patients with 55 screw-type implants replacing mandibular molars or premolars, 11/9 patients with 34/21 implants were randomized to a study/control group receiving immediate occlusal/non-occlusal restorations. Occlusal loading was defined as full loading in maximum intercuspidation. Single-unit and splinted multi-unit restorations were considered. Crestal bone levels, implant survival, and implant success were evaluated
6 months after insertion.

Results: Both groups revealed similar levels of marginal bone consistent with previous reports. No implants were lost (overall survival: 100 %) or found to fail (overall success: 100 %). No significant intergroup differences were noted for any of the evaluated parameters.

Conclusions: No differences between implants supporting either occlusal or non-occlusal immediate restorations were noted. Larger long-term RCTs are needed to confirm the final evidence and predictability of immediate functional loading as a standard treatment concept for the partially edentulous jaws.

Keywords: immediate loading dental implants; functional; non-functional; occlusal loading

Cite as:

Lorenzoni M, Stopper M, Wegscheider WA, Vogl S: Immediate occlusal versus non-occlusal loading of implants: a randomized clinical pilot study. Z Zahnärztl Implantol 2014;30:204–215

DOI 10.3238/ZZI.2014.0204–0215

Background

Recent treatment concepts in implant dentistry have been developed with the objectives of exposing patients to as few surgical interventions as possible and of sparing them postoperative discomfort. A major step in this direction has been to introduce concepts of immediate loading for use both in the mandible and in the maxilla. Immediate loading protocols have since been extensively discussed in the literature and found to be a viable treatment approach in selected cases [3, 5–7, 11, 20] with implant survival rates of 95?98.8 % in the posterior mandible [2, 10, 27].

Bruxism and severe clenching have been suspected to increase the risk of failure among immediately loaded implants [16]. To avoid this kind of complications, non-functional protocols of immediate loading have been introduced with the objective of protecting newly inserted implants from exposure to any excessive functional or parafunctional forces in partially dentate patients.

The real problem, however, might be in the current paucity of information on any effects of immediate functional provisionalization [13]. Recent studies have reported lower implant survival rates after immediate functional loading than after both non-functional immediate restoration and delayed loading [24, 31]. Other authors, by contrast, did not note any differences between immediate functional and non-functional loading regarding implant survival, bone loss, or soft tissue healing [10, 12].

The aim of this prospective randomized pilot study was to assess changes in marginal bone levels, implant success, and implant survival after immediate functional versus non-functional loading of posterior implants in partially edentulous patients.

Materials and Methods

The study was conducted following the ICH-GCP Guidelines for Clinical Trials and the Declaration of Helsinki as revised in 2008. Institutional approval was obtained from the local ethics commission at the Medical University of Graz (ref: 23–202 ex 10/11).

Patients: 20 patients were enrolled in this pilot study between March 2011 and April 2012, all of them giving their informed consent after being comprehensively informed about the study. A total of 59 implants were originally planned. All patients were treated at our center exclusively. Each patient was screened by reviewing his or her medical history, obtaining a panoramic radiograph, performing a clinical examination and taking an alginate impression (Xantalgin select; Heraeus Kulzer, Hanau, Germany). Only adult patients showing partial edentulism in posterior segments with no need for extensive grafting were included in the study. Patients were excluded if they presented with a smoking habit (> 10 cigarettes a day), active inflammation in the target area, metabolic disease, previous irradiation or chemotherapy in the head-and-neck-area, treatment with bisphosphonates, pregnancy or parafunctional habits with evidence of severe bruxing or clenching. All restorations were planned by an experienced clinician using a restoration-driven approach. Three-dimensional implant planning was prepared by fabricating a radiopaque scan prosthesis for each patient from a self-curing resin (Paladur; Heraeus Kulzer) mixed with a barium-sulfate powder (mixing ratio 3:1).

Radiographic examinations: A diagnostic orthopantomogram (Orthophos XG Plus; Sirona, Bensheim, Germany) was obtained during the screening visit. Three-dimensional imaging included a computed tomography (CT) scan in 1 patient and cone-beam computed tomography (CBCT) scans in 19 patients. A Somatom Sensation 16 unit (Siemens, Bensheim, Germany) was used for the CT scan (collimation: 16 × 0.75 mm; layer thickness: 0.75 mm; increment: 0.5 mm; 12 kV; 80 mAs; field of view: 105 cm; rotation time: 0.75 s; kernel: H60 sharp) and a Promax 3D unit (Planmeca Oy 00880, Helsinki, Finland) for the CBCT scans (kV: 8G; mA: 14; 12 s).

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