Two Interforaminal Implants in an Immediate or Delayed Loading Protocol for the Elderly

The study population comprises 20 completely edentulous patients aged 60 years and older with severe mandible resorption. Each patient receives two inter-foraminal implants (Neoss Ltd., Harrogate, UK). Following randomization, implants are loaded either immediately after dental implant surgery or three months after implant placement with the Locator®-abutment system. At follow-up visits 3, 6 12, 24 and 36 months after loading, implant stability is evaluated with Periotest® and Ostell®.

Hypothesis:

Especially for gerontoprosthetics, the Locator® abutment system offers the possibility of a minimally invasive retention of prosthetic total restorations of edentulous mandibles. The reduced number of 2 interforaminal implants is intended to ensure implantological anchoring with minimal surgical, technical, financial and time expenditure.

Research Question:

How safe is this minimally invasive and cost-effective implant and anchoring system in terms of long-term outcome? Are the two implant-prosthetic procedures (immediate versus late restoration) different in terms of implant survival time?

Materials and methods

Enrollment:

* 20 patients without relevant pre-existing conditions, from the age of 60 years
* edentulous mandible, alveolar ridge atrophy

Statistical Analysis:

When planning the study, it is estimated that bone resorption in the peri-implant area of the immediate-care implants is greater than in the late-treated implants. 10 patients per group are required with a t-test (α = 0.05) and a power of 80% if the null hypothesis is formulated as follows: -difference of means is 0 and the alternative - expected difference of means is 1mm, common standard deviation is 0.75.

Collective A (open healing - immediate loading): Insertion of a new, prefabricated total mandibular prosthesis on the day of the operation immediately postoperatively after screwing in the Locator® abutments.

Polymerization of the corresponding Locator® matrices in the newly incorporated lower jaw denture in the patient's mouth.

Collective B (closed implant healing - conventional loading): 3 months after implantation Exposure of the primary closed implants. Immediately following insertion of the prefabricated full-thickness UK prosthesis and retention by the implants using Locator® abutments.

Test parameters:

1. Intraoperative torque measurement in Ncm
2. Radiological measurement of periimplant bone height using orthopantomogram
3. 4-point measurement of peri-implant probing depth using WHO periodontal probe. The measurement is mesial, distal, buccal and lingual of the implant.
4. Measurement of bleeding on probing (parameters of peri-implant inflammation) using the WHO periodontal probe.
5. Analysis of implant stability using the Periotest® and Osstell® measuring instruments according to a standardized scheme: The strength values are performed in a measuring range consisting of a straight line through the center of the implant and the resulting 180 ° circle sector anterior to this line results. After multiple measurements (5-fold) the lowest numerical value for the Periotest® and for the RFA (Osstell®) the lowest value documented.

Eligibility Criteria:
Inclusion Criteria:

* 60 or older
* edentulous lower jaw with advanced atrophy
* poor fit and retention even with a new prosthesis

Exclusion Criteria:

* poor general condition (ASA classification grade IV or more), or
* high risk situations for implant therapy (e.g. disorders of bone metabolism due to antiresorptive therapy)