Original study - ZZI 03/2009

Bone remodeling around dental implant surfaces

G. Weibrich1, 2, W. Kleis2, R.S.R. Buch2, T. Hansen4, Ph. Streckbein2, 3

This study analyzed the effect of four different implant surfaces on bone regeneration in vivo. In twelve female beagle dogs, four different titanium screw implants (Branemark MK III, Osseotite, Xive and Compress) with four different surfaces (TiUnite, Osseotite, Friadent Plus and machined/sandblasted, respectively) were inserted in the mandible. Intravital fluoro-chrome staining was performed in the 1st (alizarin), 2–3rd (calcein green), and 4–5th (xylenol orange) weeks. Five animals were analyzed histologically and histomorphometrically after six weeks and six were analyzed after twelve weeks. At six weeks, the median peri-implant fluorochrome labeling (% of marked bone surface), a marker of bone regeneration, was slightly greater for Xive (73.38 ± 10.3 %) and Brane-mark (69.97 ± 25 %) than for Compress (54.47 ± 17.5 %) and Osseotite (49.53 ± 9.5 %). At twelve weeks, the Xive implants had the highest median bone-implant contact rate (BIC) (72.36 ± 8.21 % vs. Branemark 53.37 ± 9.74 %, Osseotite 47.47 ± 11.95 %, and Compress 42.7 ± 5.7 %). Peri-implant bone regeneration (fluorochrome staining) and the resulting BIC did not differ significantly among the four implant surfaces at six or twelve weeks (sign test, all p ? 0.063). This study demonstrated that these four implant surfaces did not differ significantly in their effect on peri-implant bone regeneration and the BIC.

Keywords: Animal study, dental implant, implant surface, peri-implant bone, polyfluorochrome, histomorphometry

Introduction

In recent years, most of the clinically available implant systems have introduced modified implant surfaces, with each manufacturer claiming that his surface structure optimizes osseointegration. Most of the studies conducted hitherto have compared the smooth (machined) surface with the corresponding new surface modification from the same manufacturer. These histomorphometric studies show that a higher bone-implant contact rate (BIC) results from increased and faster bone regeneration on the modified roughened implant surfaces [20, 22, 10]. Clinical use of one of these implant surface modifications, namely an anodized and oxidized surface (TiUnite), improved the implant survival rate of dental implants inserted in the maxilla and mandible with immediate loading from 80 % to 97 % compared with use of a machined implant surface from the same manufacturer, using a similar study design [4, 5], indicating the possible clinical relevance of such surface modification. There have so far been very few studies that compare the roughened surfaces of clinic implant systems available from different manufacturers:

Initial comparative cell culture studies suggest that the corundum-blasted and acid-etched titanium surface offers an advantage compared with plasma-sprayed and machined surfaces [13]. In an animal model, the acid-etched surface demonstrated an advantage compared with machined, plasma-sprayed and corundum-blasted surfaces [1].

The present study compares the histological and histomorphometric results of four clinically available titanium screw implants with different surface structures with regard to the resulting peri-implant bone remodeling and BIC in the medium-term and late osseointegration period.

 

Material and methods

Animal model

Following approval by the animal experiment committee, twelve female beagle dogs aged twelve to 15 months and weighing 12–16 kg were included in the study. The animals were kept in individual cages in the Boehringer Ingelheim animal experiment institute and were given water and standard feed. Three months before the study, the mandibular premolars were removed. All of the wounds were reviewed clinically and showed normal hard and soft tissue healing.

 

Surgical procedure and implant design

After induction of anesthesia by intramuscular injection of Dormitor (Orion Corporation, Espoo Finland) (35 µg medetomide per kg body weight) and intravenous injection of Disoprivan (AstraZeneca AG, Grafenau 10, CH-6301 Zug) 2 % (2 mg propofol per kg body weight) four different implants were inserted randomized in the mandible according to the manufacturer’s instructions.

The following implant types with different implant surface structures were inserted in randomized positions (Fig. 1):

1. Branemark (MK III): a self-tapping cylindrical titanium screw implant, Nobel Biocare (Göteburg, Sweden), length 7 mm, diameter 3.75 mm. The TiUnite surface is produced by anodized oxidation.

2. 3i Osseotite: a self-tapping cylindrical titanium screw implant, 3i (Miami, FL, USA), length 8.5 mm, diameter 4.0 mm. The Osseotite surface is acid-etched twice.

3. Xive: a self-tapping conical titanium screw implant, Densply Friadent (Mannheim, Germany), length 8 mm, diameter 3.8 mm. The Friadent Plus surface is corundum-blasted and acid-etched.

4. Compress: a bone-compressing/condensing conical titanium screw implant, IGZ eG (Diez, Germany), length 12 mm, diameter 4.0 mm. The apical third of the surface is machined and sand-blasted.

 

The wounds were closed with Vicryl 3.0 (Ethicon GmbH; Norderstedt, Germany). The dogs were given soft feed for two weeks postoperatively.

 

Antibiotic protection and fluorochrome labeling sequence

As postoperative antibiotic cover, the animals were given an intramuscular injection of Tardomycel (BayerVital, Leverkusen, Germany) (procaine benzyl penicillin) 0.1 ml/kg body weight directly preoperatively and then every 48 hours for an overall period of ten days.

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