Original study - ZZI 01/2015

Clinical results of one-stage augmentation with autologous bone rings and Ankylos implants after 5 years of loading in an atrophied mandible

B. Giesenhagen1

Objective of the study: The study was carried out to measure the success rate of bone ring augmentation, simultaneous placement of Ankylos implants (DENTSPLY Implants Manufacturing GmbH, Mannheim, Germany) and prosthetic restoration with fixed bridges and crowns after 5 years of loading.

Material and methods: 14 patients were treated with 25 bone rings, mainly harvested from the chin. Six were placed in the anterior region, 7 in the premolar area and 12 in the molar region. X-rays were taken pre- and postoperatively to document the bone level in relation to the implant shoulder. Bone ring and implant healing was closed. Reentry took place 6 months later and the implants were restored with fixed crowns and bridges. Five years after loading further X-rays were taken to measure the crestal bone in relation to the implant shoulder. Parameters for failure were postoperative complications, failed implants and bone resorption in the region of the implant shoulder.

Results: All patients participated in the follow-up. No implant was lost (100 % survival rate). 3 implants (2 patients) had postoperative complications but these had no influence on the crestal bone level after 5 years of loading. 4 implants (2 patients) showed a little resorption in the crestal bone area. The donor region and implant position had no significant influence on periimplant bone loss.

Conclusion: Despite the limitations of the study, the bone ring technique has advantages compared with other augmentation techniques with autologous bone. Due to the standardized Instruments for ring harvesting and ring bed preparation the bone ring fits perfectly into the ring bed. The implant fixes the ring on top and achieves very good primary stability in the bone.

Keywords: bone ring; vertical augmentation; autologous bone; highly atrophic mandible; trephine

Cite as: Giesenhagen B: Klinische Fünfjahresergebnisse nach einzeitiger Augmentation mit autologen Knochenringen und Ankylos-Implantaten im atrophierten Unterkiefer. Z Zahnärztl Implantol 2015;31:52–63

DOI 10.3238/ZZI.2015.0052-0063

Introduction

Implant restoration in the edentulous jaw often requires additional augmentation measures on account of the physiological remodeling and resorption processes following tooth loss and the associated reduction in bone availability.

Besides guided bone regeneration (GBR), the methods used most frequently today to increase bone volume and raise the absolute ridge level are distraction osteogenesis, bone-splitting procedures and onlay and inlay bone grafts [7, 25]. On the basis of current evidence, none of these four methods has a clear therapeutic advantage when they are compared directly [7, 10].

Despite the good clinical results achieved to date with xenogeneic and allogeneic bone substitutes, autologous bone grafts continue to represent the gold standard for filling defects and for bony regeneration, according to our current understanding [3, 13, 19]. Since bone used for autologous grafts is usually obtained from intraoral donor regions, little autologous bone is available for augmentation. Other disadvantages are that the additional intraoral bone harvesting procedure is stressful for the patient and can increase the risk of potential postoperative complications at the donor site. Complications after bone harvesting lead to what is known as donor morbidity, manifested as hematoma, secondary hemorrhage, infection and delayed wound healing at the donor site [23].

Unlike the current method of harvesting intraoral bone in block form, the bone ring is a simple possibility of obtaining donor bone in ring form and performing reconstruction of three-dimensional defects and absolute ridge augmentation with autologous bone in a minimally invasive procedure. This procedure, developed about 8 years ago by the author, enables a one-stage minimally invasive procedure to harvest and graft autologous bone to be combined with simultaneous implant insertion.

Since primary stability of implant fixation, according to current knowledge, is possible only with a local bone thickness of 4 mm, clinical experience has shown that there is an increased risk of implant failure with a one-stage procedure [26]. A one-stage method is therefore not usually recommended in cases with extensive resorption [15, 18, 26].

However, the one-stage method has the advantage that combining augmentation and implant insertion contributes to less patient stress and greater patient acceptance. By means of the bone ring method, primarily stable implant insertion is achievable in a one-stage procedure even when local bone availability is low. This is made possible by the fact that the ring-shape bone graft can be fixed both by the implant and by additional use of membrane screws if necessary [8, 11, 28].

Material and Method

A total of 14 patients (9 women and 5 men) were included in the study. They were recruited from the author’s dental practice clientele. All of the augmentation and implantation procedures were performed in the mandible. Besides consent to take part in the study, the inclusion criterion was that the patients should have undergone prosthetic restoration in the region of the augmentation and implant insertion at least 5 years previously. Other inclusion or exclusion criteria were not defined. At the time of the start of treatment, the patients’ ages were between 25 and 87 years. The general medical history of all participants was unremarkable. Age, sex and smoking were not included as study parameters.

PAGE: 1 | 2 | 3 | 4