From practitioner to practitioner - ZZI 03/2011

Comparison of lateral augmentation techniques
Spreading of the alveolar ridge, augmentation with autologous bone blocks and
membrane augmentation in the dental practice

M. Dürholt1, D. T. Weinhold2, S. Dax3, S. Schulz4

Question: A multitude of surgical techniques for the augmentation of vertical bones in connection with the insertion of dental implants is described in the relevant literature. The objective of the present article is to compare three techniques of vertical ridge augmentation on the basis of our medical records of patients who have undergone the described treatments in the past.

Method: The following methods were examined: spreading the alveolar ridge [12, 13, 14] by means of oscillating saws and spiral osteotomes, bone block grafts taken from the mandibular angle area [1, 4, 6, 11] and the use of absorbable membranes [3, 8]. All patients that complied with the guidelines of the DGZMK for the insertion of dental implants were registered. The patient population was not differentiated in more detail. Complete and partial loss of the augmentation material as well as a dehiscence of the suture were rated as complications [7].

Results: A complication rate of 3 % was determined for the spreading of the alveolar ridge, the rate established for bone block grafts was 19 % and that of the membrane techniques was 32 %.

Conclusion: The spreading of the alveolar ridge showed significantly less complications than the other two augmentation techniques we examined. Due to the design of the study and the inhomogeneity of the patient group, this result was affected by a number of other factors which could not be included in the statistics. Prospective studies regarding this topic are desirable.

Keywords: bonegrafts; GBR; lateral ridge augmenation; lateral augmenation success; split osteotomy; retrospective study

Introduction

The delayed placing of implants frequently confronts dentists with the problem of an atrophic alveolar ridge. In these cases, the options are to either insert an implant with a reduced diameter or to carry out an augmentation of the alveolar ridge. While horizontal bone defects are normally treated by oral surgeons, vertical bone deficits are a welcome challenge to experienced implantologists. Thanks to the development of oscillating bone saws and spiral osteotomes, the spreading of the alveolar ridge has become a gentle alternative to conventional treatments such as augmentations with bone blocks or membranes. The present article compares different methods of vertical augmentation of the alveolar ridge on the bases of our medical records of patients who have undergone such treatments in the past.

Method and material

Patients

The subject matter of the present study is a comparative analysis of different augmentation techniques from a retrospective point of view. A total of 57 patients were chosen who had undergone different treatments prior to insertion of an implant, i. e. spreading of the alveolar ridge (group 1: n = 28 patients) or augmentations with membranes (group 2: n = 14 patients) or bone blocks (group 3: n = 15 patients), depending on the clinical situation. The patients were treated in the dental practice of Dr. Dürholt (Bad Salzuflen, Germany; main focus: implantology) and Dr. Weinhold (Memmingen, Germany; oral surgeon). There were no contra-indications as stipulated in the guidelines of the DGZMK concerning the insertion of implants in the past medical history of the patients. What all patients had in common was an isolated vertical pre-operative bone defect, however none of them suffered from horizontal loss of bone which would have affected the therapy. The height of the patients’ residual bone was determined either by means of measuring devices as part of an orthopantomogram or by direct measurement as part of digital volume tomography (CBCT).

Clinical sequence

Spreading of the alveolar ridge

Jaw segments in the upper and lower jaw were operated on according to this technique, with the exception of the molar region of the upper jaw, where a spreading of the alveolar ridge is not possible due to the anatomic vicinity of the maxillary sinus. The size of the spread areas ranged from restorations of individual teeth to the restoration of the entire upper jaw (ten teeth). No spreading of the alveolar ridge could be carried out in those cases where the width of the remaining jaw was less than 2 mm. Once the alveolar ridge had been exposed, the bone was split by means of sound driven oscillating saws (Sonosurgery, Gebr. Brasseler, Lemgo, Germany) (fig. 1). The depth of the split was identical to the intended length of the implant. The preparation was extended by one implant size in both mesial and distal direction in order to guarantee sufficient mobilization (fig. 2). If this was not practicable due to residual dentition or bone qualities of D2−D1 according to Mish , relief cuts were created in the cortical bone of the element to be mobilised (fig. 3). The bone was expanded with spiral osteotomes (MaxilloPrep Spread-Condense; Gebr. Brasseler, Lemgo, Germany/Split Control Plus; Meisinger, Neuss, Germany) and manual wrenches or ratchets, depending on the system (fig. 4, 5). When several adjacent implants had to be inserted, a successive exchange of the screws against implants proved to be advantageous as this prevented the resetting of the bone structures (fig. 6). The remaining split areas were filled with particulate material (Cerasorb 250–500 µm; Curasan, Kleinostheim) (fig. 7). To mobilise the mucosa, a slit was cut into the periosteum or a mucosa flap was created. The button sutures closing the wound could be removed after ten days.

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