Australian Dental Journal
The official journal of the Australian Dental Association
Australian Dental Journal 2016; 61: 62–70 doi: 10.1111/adj.12313
Autogenous bone and a bovine bone substitute for ridge preservation: preliminary clinical and histologic findings MC Schulz,* MB Kallweit,† S Kallweit,† R Koch,‡ G Lauer,* R Mai,* T Hoffmann§ *Department of Oral and Maxillofacial Surgery, Faculty of Medicine ‘Carl Gustav Carus’, Technische Universit€at Dresden, Dresden, Germany. †Private Practice, Kirchberg, Germany. ‡Institute for Medical Informatics and Biometry, Faculty of Medicine ‘Carl Gustav Carus’, Technische Universit€at Dresden, Dresden, Germany. §Department of Periodontology, Faculty of Medicine ‘Carl Gustav Carus’, Technische Universit€at Dresden, Dresden, Germany.
ABSTRACT Background: Tooth extractions lead to morphological changes of the alveolar ridge. For oral rehabilitation sufficient bone volume of the alveolar ridge is required. This clinical study compared the ability of Bio-Ossâ Collagen to autogenous bone to preserve bone volume after tooth extraction. Methods: A total of 17 patients with 20 extraction sites were examined. After extraction, 10 sockets were each filled with either autogenous bone or Bio-Ossâ Collagen and covered with a resorbable membrane. The width of the alveolar ridge was measured postoperatively, and after 4 and 6 months respectively. Prior to implant insertion, a bone biopsy was taken from the grafted sites and evaluated histologically. Results: The width of the alveolar ridge in the Bio-Ossâ Collagen group decreased about 5.33 6.62% after 4 months and 9.45 10.51% after 6 months. The reduction in the group augmented with autogenous bone was 14.31 21.41% after 4 months and 19.17 8.38% after 6 months. No statistically significant differences were observed. The histological examination showed comparable area fractions of total bone in both groups (Bio-Ossâ Collagen: 59.99 24.23%; autogenous bone: 61.55 25.13%; p = 1.0). Conclusions: The present study demonstrated that autogenous bone and Bio-Ossâ Collagen are suitable for ridge preservation. However, both techniques could not entirely prevent tissue volume loss. Keywords: Autogenous bone, bone substitutes, clinical research, histology, wound healing. (Accepted for publication 22 March 2015.)
INTRODUCTION Tooth extractions lead to considerable changes in the height and width of the alveolar ridge. In a clinical study, Schropp et al. demonstrated that tooth extractions cause the loss of up to 50% of the alveolar width in the posterior regions.1 Two-thirds of this loss occurred in the first 3 months. In the aesthetic zone, a pronounced loss of buccal bone was observed after tooth extraction.2 Ara ujo and Lindhe found that the resorptive process is pronounced in the crestal area of the buccal alveolar wall.3 According to Horv ath et al., the reasons for these changes are periodontal diseases, periapical lesions, trauma and traumatic extraction methods.4 However, for oral rehabilitation a sufficient bone volume of the alveolar ridge is required, e.g. implant therapy would require bone dimensions of 6–7 mm.5 A pronounced loss of bone leads to difficulties in placing implants in a position suitable 62
for prosthodontic restoration.6 Different techniques have been evaluated to perform preservation of ridge preservation, such as barrier membranes, autogenous or xenogenous graft materials or combinations of these methods. The application of membranes has shown positive results for alveolar ridge protection. For guided tissue regeneration, they can be used either alone or in combination with bone substitutes.7,8 Membranes have a barrier function to prevent the ingrowth of connective tissue or epithelium in the extraction alveolus.9 This may support an uneventful healing of the extraction sites.10 In reconstructive surgery, autogenous bone grafts obtained from intraoral or extraoral grafting sites are considered the ‘gold standard’. Their main properties are osteogenicity, osteoinduction and a lack of immunogenicity.11 However, harvesting from intraoral sites might cause some discomfort. A second sur© 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone gery at the harvesting site is required with possible wound healing disturbances, swelling and bleeding.12 Furthermore, depending on the donor site, disturbances in the sensation of the skin of the chin, tongue and mucosa as well as negative pulpal sensitivity might occur.13,14 Therefore, various xenogenic and synthetic bone substitutes are available for bone grafting. Their advantages are unlimited availability and no need for a second surgical procedure. One of these xenogenous materials is Bio-Ossâ Collagen, which is obtained from deproteinized bovine bone. Wong and Rabie augmented a defect in the parietal bone of New Zealand rabbits with either collagen or the bovine bone substitute.15 They demonstrated a stimulation of bone formation. In another animal study, Bio-Ossâ Collagen was used to graft a buccal gap situation with satisfactory results.16 Ara ujo et al. demonstrated an enhanced volume of hard tissue in the crestal area of dental implants after grafting with the substitute.16 In an animal study by Fickl et al., Bio-Ossâ Collagen showed a preventive effect of volume loss in extraction sites.17 Heberer et al. found histological indeterminate results of bone formation in human extraction sockets after a healing period of 6 weeks when augmented with bovine bone.18 The sites showed a range from prevalent provisional matrix to matured bone similar to healing periods up to 3 months. However, there might be a higher risk of delayed healing when using grafting materials.6 The objective of the present study was to examine the volume stability and histological behaviour of BioOssâ Collagen and autogenous bone in combination with the Bio-Gideâ membrane. It was hypothesized that Bio-Ossâ Collagen in combination with a resorbable membrane could preserve more volume compared to autogenous bone in a clinical situation. Thus, a sufficient preservation of bone volume for implant placement would be possible without any donor site morbidity.
Eleven molars, 6 premolars and 3 incisors were extracted. Indications for tooth extraction were nontreatable endodontic lesions (11 teeth), extensive caries lesions (6 teeth) and longitudinal fractures (3 teeth). The inclusion and exclusion criteria are listed in Table 1. The patients were assigned to a treatment group according to the necessity of a second surgical intervention to harvest autogenous bone, e.g. the operative removal of a wisdom tooth. For periodontal screening, probing depth according to the periodontal screening index, approximal plaque index and sulcus bleeding index were recorded. All patients received professional tooth cleaning and showed no signs of inflammation (swelling, bleeding on probing) prior to extractions. Materials Commercially available blocks of Bio-Ossâ Collagen (Geistlich Pharma AG, Wolhusen, Switzerland) were used as a bone substitute. The material consists of spongious, deproteinized, bovine bone containing 10% collagen type I. The blocks were adapted to the extraction socket by cutting prior to insertion. The Bio-Gideâ membrane (Geistlich Pharma AG, Wolhusen, Switzerland) was used to cover the alveolus. The resorbable membrane of 25 mm 9 25 mm consisted of porcine collagen type I. The autogenous bone was obtained from the posterior mandible using piezo surgery (Piezosurgeryâ, mectron Deutschland Vertriebs GmbH, K€ oln, Germany). To reduce patient inconvenience, the intervention was performed in the context of an operative removal of the third molar. The patient’s own blood was collected from the defect using a syringe. Combined cortical and spongious bone blocks of 15 mm 9 10 mm 9 10 mm were ground in a bone mill. The bone was stored in the patient’s own blood until insertion into the socket.
MATERIALS AND METHODS This clinical study was undertaken in accordance with the Declaration of Helsinki on medical protocols and ethics involving human subjects. The trial was prospective, non-randomized, non-blinded and performed in a private practice. The study was approved by the Ethical Review Board of the University of Freiburg, Germany (08/1210). All patients provided written consent for participation in the study. Patient selection Seventeen patients (average age: 47.2 years, range 28– 59 years; 11 female, 6 male) with 20 extraction sites (maxilla: 13 teeth; mandible: 7 teeth) were evaluated. © 2015 Australian Dental Association
Table 1. Inclusion and exclusion criteria for selected patients Inclusion criteria - patients aged over 18 years - good oral hygiene - at least one adjacent tooth to extraction socket - alveolus bordered by four bony walls after extraction
Exclusion criteria - pregnancy or lactation - loss of the buccal bone wall - residual bone height less than 4 mm - smoking of more than 10 cigarettes per day - alcohol or drug abuse - rheumatism - poorly regulated diabetes - systemic bone diseases or any condition of compromised immune status 63
MC Schulz et al. Clinical procedures Prior to extraction, impressions of the jaw were taken and individual plaster casts were produced. Splints for standardized measuring were manufactured. Bone mapping was performed directly following extraction, after 4 and 6 months (prior to implant insertion). Therefore, 6 vertical rows of each 5 measuring points were set per tooth – 3 lingual and 3 buccal: mesial, median, distal (Fig. 1). The cervical measuring points were set at 2 mm below the gingival margin. The distance between the measuring points was 2 mm respectively. Thus, the alveolar width was measured after administration of local anaesthesia (Ubistesinâ 1:100,000; 3M Deutschland, Neuss, Germany) and the surgical procedures carried out by one experienced surgeon. The thickness of the mucosa was measured using a graded probe penetrating the gingiva orthogonally to the bone. A metal stop was used to mark the penetration depth of the probe. The stop was fixed into position and after measuring, each value was transferred to the plaster cast by marking the penetration depth. The extractions were performed atraumatically using a scalpel and a periotom. Multirooted teeth were hemi- or trisectioned before extraction. After careful debridement, the socket was clinically inspected using a dental probe to ensure that all four bony walls were intact. If no mobility or fenestration of the bony walls was detected by probing, the alveolus was filled to the margin with Bio-Ossâ Collagen or autogenous bone respectively. Care was taken to ensure that the Bio-Ossâ Collagen was saturated with blood. To cover the material, a Bio-Gideâ membrane was fixed in a double layer without undermining the adjacent mucosa using two mattress sutures with Seralonâ (Serag-Wiessner KG, Naila, Germany). The wound was allowed to heal by secondary intention. For postoperative analgesia and prevention of inflammation, the patients received 2 9 600 mg ibuprofen per day for 2 days (Aliudâ Pharma GmbH, Laichingen, Germany). From the second day after extraction, the patients used Chlorhexamed fluid 0.1% (GlaxoSmithKline Consumer
Healthcare GmbH & Co. KG, B€ uhl, Germany) for plaque control. Follow-up care was performed on day 1, 4 and 7 postoperative. The sutures were removed after 7 days. Four and 6 months after extraction (14 days), bone mapping measurements were repeated analogically to the first time point. The splints were lined with Honigum light (DMG Chemisch-Pharmazeutische Fabrik GmbH, Hamburg, Germany) to reproduce the current profile of the alveolar ridge. Plaster casts were then manufactured. Six months after extraction, the implant insertion was undertaken with local anaesthesia. A crestal incision was made and the mucoperiosteal flap elevated to expose the implant site. A bone biopsy of the centre of the extraction socket was obtained using the drilling core of a trephine burr with an inside diameter of 2 mm and a length of 5 mm (DIT Diamanttechnik GmbH & Co. KG, Oberlungwitz, Germany). Implant insertion (alphatecâ BONITexâ surface, Henry Schein Deutschland GmbH, Langen, Germany) using burrs and osteotomes then followed. All implants could be placed without additional augmentation. The mucoperiosteal flap was repositioned and fixed with mattress sutures using Seralonâ. The wounds were allowed to heal by primary intention. Postoperative treatment was carried out identically to that following the extractions. Dynamic profile of the alveolar ridge After lining the measuring splint, three plaster casts of each site were manufactured. The casts were cut in an orobuccal direction at each measuring row and values were transferred on the sections (Fig. 2). Thus, three sections per site and time point were obtained. The thickness of the mucosa was marked along the measuring rows on each section using the probe with the metal stop indicating the penetration depth. By linking the marked points, the hard tissue profile could be transferred onto the sections. Subsequently, the sections were scanned and the width of the alveolar crest was measured. Histological preparation and examination
Fig. 1 Splint for standardized measuring on cast model. Three rows (mesial, median, distal) of each 5 measuring points are located on the buccal and oral site. 64
After dehydration in a graded series of ethanol, all drill cores were removed from the trephine burr and embedded in methylmethacrylate (Technovitâ 9100 NEU, Heraeus Kulzer, Wehrheim, Germany). 500 lm thick axial sections in an orobuccal direction of each specimen were cut with a diamond saw system (Exaktâ–Mikro–Schleifsystem; Exakt-Apparatebau, Norderstedt, Germany) according to Donath’s microsectioning and grinding technique.19 The axialsectional thickness was reduced to 50 lm using a roll © 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone The histological evaluation focused on potentially inflammatory reactions and on the qualitative evaluation of bone formation. For histomorphometrical analysis, the whole area of the drill core was used. The amount of mature and immature bone, stromal tissue and remaining bone substitute was quantified. Therefore, the appropriate area fractions were detected semi-automatically by tracing the contours of the structures and measuring the corresponding areas. Mature and immature bone was distinguished by the microscopical structure. Subsequently, the ratios of mature and immature bone, stromal tissue and remaining bone substitute to the complete area of the drill core were calculated. Statistical analysis Statistical software SAS (SAS Institute Inc., Cary, NC, USA) was used for all analyses. The mean values and standard deviations of the alveolar width were calculated. Statistical analysis was performed using linear models of covariance analysis for repeated measures. The treatment group was set up as a test factor and the baseline value served as quantitative covariable. A compound symmetry was assumed for the covariance structure of the time points. A Tukey-adjusted test procedure was used to compare the adjusted means. For histological measurements, the ratios of bone, residuals of Bio-Ossâ Collagen and stroma were calculated. Comparisons of the mean values were performed using non-parametrical U–tests. The level of statistical significance was set at a = 0.05. RESULTS Clinical results
Fig. 2 Cast sections of the alveolar ridge profile at extraction sites. (a) The black dots indicate the measuring points for the hard tissue profile. (b) The fractions of hard (blue) and soft tissue (red) are calculated by colour labelling.
grinder containing sandpaper with decreasing grain size (Exakt-Apparatebau, Norderstedt, Germany). Subsequently, the specimens were stained with Masson-Goldner staining. The whole drill core was imaged parallel to the length axis in an orobuccal direction using light microscopy (Olympus BX61, Olympus Deutschland GmbH, Hamburg, Germany). Multiple image alignment was possible, using an automatic scanning table (L-Step 12/2, M€ arzh€ auser, Wetzlar, Germany). Nine images per sample were scanned under 10-fold magnification and fused to one image. © 2015 Australian Dental Association
All 17 patients completed the study. Two patients (1 Bio-Ossâ Collagen; 1 autogenous bone) suffered from mild inflammation following tooth extraction, which was easily treated with a local application of Chlorhexamed fluid for 5 days. No surgical revision was necessary. The soft tissue coverage on postoperative day 1 and 4 was uneventful in all patients. Thus, removal of the sutures was possible after 7 days. After 6 months, the profile of the alveolar ridge appeared concavely in horizontal and vertical dimensions. At the donor site, no wound healing disturbances occurred. No affection of the mandibular nerve was observed. Dynamic profile of the alveolar ridge After 4 and 6 months, there was a noticeable reduction of alveolar width for both methods used. This reduction was more pronounced after 6 months than after 4 months. The crestal part of the extraction 65
MC Schulz et al. socket was affected more than the apical part. The loss of alveolar width was slightly higher in the group grafted with autogenous bone. This reduction was more pronounced after 6 months than after 4 months. The metric data are shown in Table 2 and the percentages in Table 3. The loss of alveolar width for both groups was not statistically significant after 4 and 6 months (p = 0.0745 for both time points). The buccal lamella was affected more when compared to the oral one, demonstrated by a concave vestibular profile of the ridge. The highest decrease was observed in the posterior maxilla. Extraction sites in the mandible premolar region showed the lowest reduction. The differences observed between both groups were not statistically significant (p = 0.4556).
woven bone. Signs of inflammation or osteolysis could not be observed. In biopsies following grafting with autogenous bone, maturation of bone was more pronounced compared to Bio-Ossâ Collagen. A dense meshwork of trabecular bone could be observed in the apical area of the samples. Areas of woven bone and stromal tissue were less pronounced compared to Bio-Ossâ Collagen. No signs of inflammation could be detected (Fig. 3a and 3b). Histomorphometry Histomorphometrical results showed comparable areas of bone and stroma in both groups. No statistically significant differences could be observed. Almost no remnants of Bio-Ossâ were detected. Details are shown in Table 4.
Histomorphology After 6 months of healing, sites filled with Bio-Ossâ Collagen showed a spongious trabecular meshwork of mature bone. A layer of woven bone covered the trabeculae, indicating new bone formation. Large areas of stromal tissue could be found between the trabeculae over the entire sample. The few remaining parts of Bio-Ossâ Collagen were integrated in formations of
DISCUSSION The present study compared the volume stability and histological behaviour of Bio-Ossâ Collagen to autogenous bone in a clinical situation. Therefore, the dynamic profile of the alveolar ridge was examined
Table 2. Reduction of the alveolar ridge width in millimetres for each region measured after 4 and 6 months (mean values of each vertical measuring row) BioOssâ Collagen Reduction in mm mesial Region 35 17 25 16 44 16 26 47 26 23
4 months 0.3 0.6 1.5 1.4 0.3 1.3 0.6 0.5 0.4 0.5
median 6 months 0.3 1.3 2.4 1.9 0.9 2.0 1.0 0.9 0.8 1.2
4 months 0.4 0.4 0.5 0.9 0.2 0.9 0.8 0.5 0.3 0.4
distal 6 months 0.8 0.5 0.9 1.4 0.5 1.1 1.5 1.0 0.8 0.5
4 months 0.1 0.9 0.8 1.0 0.2 0.5 1.0 0.6 0.3 0
6 months 0.3 1.0 1.3 1.2 0.4 1.1 1.5 1.1 0.5 0
Autogenous bone Reduction in mm mesial Region 46 14 36 16 34 11 26 25 12 36 66
4 months 3.1 0.5 0.5 0.8 0.3 0.5 0.6 0.4 0.6 2.4
median 6 months 3.1 1.3 2.1 1.3 0.6 0.8 0.8 1.0 1.1 2.6
4 months 2.6 0.3 0.8 1–1 0.3 0.5 0.2 0.6 0.4 2.5
distal 6 months 2.8 0.8 1.9 1.6 0.8 0.9 0.8 0.9 0.8 2.9
4 months 2.5 0.6 0.5 0.9 0.1 0.3 0.4 1.3 0.6 2.5
6 months 2.6 0.6 1.2 1.1 0.3 0.6 0.8 1.5 0.8 2.8
© 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone Table 3. Decrease of alveolar width for both groups after 4 and 6 months in percentage terms with standard deviations Bio-Ossâ Collagen
Time mesial 4 months 6 months
7.18 8.52 12.47 11.63
median 5.33 6.62 9.45 10.51
autogenous bone distal 5.42 7.64 8.97 11.17
immediately post extraction, and after 4 and 6 months. Bone biopsies were taken after 6 months, prior to implant insertion. One limitation of the study was the small number of patients and the lack of a control group without any augmentation. The clinical results demonstrated that extraction sites grafted with Bio-Ossâ Collagen showed a slight decrease of the width of the alveolar ridge after 6 months. Iasella et al. found similar results in a clinical study after 4 and 6 months.8 A decrease of 1.2 0.9 mm in horizontal width in the middle of the alveolar ridge for the preservation group was observed which is comparable to the 1.24 1.14 mm found in the present study. Compared to non-grafted extraction sockets, their differences were statistically significant. A resorption of the buccal lamella was also observed.8 The buccal part of the socket mainly consists of bundle bone in which the Sharpey’s fibres are fixed. Caused by the tooth extraction, the Sharpey’s fibres are removed and the bundle bone loses its function. During the remodelling process, it is degraded by osteoclasts. Another factor which might influence the extent of resorption is the thickness of the buccal lamella. In the present study, only sockets with intact bony walls were included. This was proved by sounding with a probe. However, the thickness of the buccal lamella was not measured intraoperatively. Another limiting factor of the study is the inclusion of single- and multi-rooted teeth. Schropp et al. stated that ridge reduction in percentage terms was lower in the premolar region compared to the molar region.1 Thus, the effects of ridge preservation after extraction of multi-rooted teeth might be more pronounced than after extraction of single-rooted teeth. However, in the anterior maxilla bone loss occurring after extraction of single-rooted teeth is expected to be higher than in the premolar and molar region.2 Thus, the current study includes a heterogeneous sampling collective. Furthermore, the elevation of a mucoperiostal flap might cause bone resorption up to 1 mm.20 Therefore, to prevent bone loss in the present study tooth extractions were performed without flap elevation. Animal studies could support these findings. Fickl et al. observed the lowest volume loss for sockets grafted with Bio-Ossâ Collagen in a study of dogs.17 The metric decrease after 2 and 4 months was -1.3 0.2 mm and -1.5 0.2 mm respectively. © 2015 Australian Dental Association
mesial 12.09 25.35 17.17 25.08
median 9.27 21.08 14.31 21.41
distal 10.07 21.29 12.93 21.50
These findings are comparable to the results of the present study. However, the higher bone turnover rate in canines has to be considered.21 Furthermore, our data are supported by the results of Araujo and Lindhe who also observed a pronounced resorption of the buccal lamella in an experimental study of dogs.3 A possible reason for this resorption might be the loss of bundle bone. Histomorphological results of the present study showed a pronounced ratio of lamellar bone in sockets filled with autogenous bone. In sites grafted mostly with Bio-Ossâ Collagen, a direct contact of woven bone to remnants of the substitute were observed after 6 months of healing. This is in agreement with Artzi et al. who found a pronounced deposit of woven bone in sockets filled with pure Bio-Ossâ granules after 9 months of healing.22 The greater amount of Bio-Oss particles may be due to different reasons. On the one hand, a denser packing could be achieved with pure Bio-Ossâ particles. This potentially delays the ingrowth of blood vessels and thus might hamper resorption. Furthermore, by using Bio-Ossâ in combination with collagen I, bone remodelling might be accelerated due to an enhancing effect of collagen I on bone metabolism.23 In animal studies, the results of the present study could be supported. Cardaropoli et al. observed granules of Bio-Ossâ Collagen embedded in woven bone structures after 3 months.24 These findings indicate good biocompatibility, demonstrating no fibrous reaction or inflammation. Furthermore, a higher ratio of lamellar bone in sockets grafted with autogenous bone compared to sites filled with BioOssâ Collagen was found in the present study. While lamellar bone represents a mature form of bone, woven bone represents a stage of the membranous ossification process. Autogenous bone has osseoinductive properties due to the fact that it contains bone morphogenic proteins which are able to change mesenchymal cells into osteogenic cells.25 In contrast, Bio-Ossâ Collagen has to be considered as osseoconductive. Its porous structure provides a scaffold for migrating bone cells and fostering their differentiation.26 Bone formation in areas grafted with Bio-Ossâ might be decelerated as resorption of Bio-Oss granules seems to be a long-lasting process. In the present study, these findings could be supported. The ratio of mature and immature bone in the different sites 67
MC Schulz et al.
Fig. 3 Histological sections. (a) shows a loose meshwork of trabecular bone (tb) and a large area of stromal tissue (s) over the entire biopsy from the crest (top) to the apical part (bottom). Only few remaining BioOssâ particles could be found (b). (b) Compared to biopsies obtained from sockets grafted with Bio-Oss, this picture shows an area of trabecular bone (tb) in the apical region of the biopsy (bottom). In the direction to the crest (top), the meshwork is wider, large areas of stromal tissue (s) can be found. Masson-Goldner-staining, magnification 1:10. 68
indicate that healing in the sockets grafted with BioOssâ Collagen is slightly delayed compared to autogenous bone. Our findings support those made by Arajo and Lindhe in a study of beagle dogs.27 After u 3 months of healing, higher ratios of mineralized bone were observed in sites containing autogenous bone compared to sockets grafted with the bovine bone substitute. However, the value of autogenous bone for ridge preservation is not clear. Their study indicated that autogenous bone chips had no preventive effect on bone resorption. This is in agreement with the present study, where autogenous bone had an enhancing effect on bone healing and maturation, but no preventive effect on ridge dimensions after tooth extractions. Due to the almost unavoidable resorption of the buccal lamella, both autogenous bone and Bio-Ossâ Collagen seem to serve as a space holder in the socket. Histomorphometric findings in the present study showed comparable amounts of bone and stromal tissue for both methods. An unexpected finding in our study was the small amount of remaining Bio-Ossâ particles detected after 6 months, as other groups observed higher amounts of Bio-Ossâ. In a clinical study, Heberer et al. found 27 7.2% of Bio-Ossâ Collagen after 6 weeks of healing.18 One reason for this might be the different healing times. Resorption of Bio-Ossâ Collagen particles after 6 months might be more advanced than after 6 weeks. However, Bio-Ossâ Collagen is typically not resorbed after 6 months. Lindhe et al. observed 19.0 6.5% of substitute particles still present after 6 months.28 When pure Bio-Ossâ was used in extraction sockets fractions of remnants were between 22.6 7.9% after 6 months and still 30.8 7.8% after 9 months.29,30 One reason for this might be the use of pure Bio-Ossâ without the addition of collagen I. The main part of the organic bone components is known to stimulate bone cell activities and therefore enhance bone metabolism.23 Therefore, the resorption of the Bio-Ossâ granules might be decelerated compared to Bio-Ossâ Collagen. Another reason might be the site the drill core was obtained from. When the drill core was harvested from the region of the interradicular septum, no large amounts of remnants of the bone substitute were to be expected. In the present study, a membrane has been used for both groups. The barrier prevents the ingrowth of connective tissue and epithelium into the extraction sockets. The membrane was used in a double layer to allow the healing in secondary intention. Thus, a sufficient stability was achieved over the soft tissue healing period. Other studies used a patch of oral mucosa to cover the augmented site.31 This might be advantageous for enhanced healing without graft exposure. On the other hand, another donor site for harvesting the mucosa is necessary. By solely using membranes and healing by secondary intention, wound dehiscence may occur. One © 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone Table 4. Area fractions of the histological sections of bone, stroma and remnants of Bio-Ossâ Collagen with their standard deviations (SD), minimum (Min), maximum (Max) in percentage terms and p-values Area fraction
Group
Mean
SD
Min
Max
p
Mature bone
Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone
41.39 51.35 18.60 10.21 59.99 61.55 39.89 38.45 0.36 –
18.43 25.96 22.90 12.57 24.23 25.13 24.06 25.13 0.46 –
16.66 20.05 0.00 0.00 23.62 24.60 5.87 4.28 0.00 –
69.05 94.33 51.25 32.65 94.13 95.72 76.38 75.40 1.32 –
0.4057
Immature bone Bone total Stroma Bio-Ossâ
reason for wound healing disturbances might be the reduced blood supply in an elevated flap which is separated from the underlying bone by a membrane.32 Furthermore, a reduction of bone volume in the augmented area might occur using membranes due to membrane exposure.7 This was not observed in the present study. This finding might be due to the fact that Lekovic elevated full thickness flaps which could lead to bone resorption. Certainly, the thin buccal lamella would be affected by this resorption by up to 1 mm.20 In the present study, tooth extraction and augmentation were performed without elevation mucoperiosteal flaps. Cordaro et al. observed slightly more wound healing disturbances when augmenting atrophic ridge sites with bone blocks and Bio-Ossâ covered with a Bio-Gideâ membrane.33 Similar observations were not made in our study. No dehiscences or signs of inflammation or infection occurred, neither clinically nor histologically. Compared to our study, the augmented sites were not fully covered by bone. This could lead to tension in the covering soft tissue causing dehiscences. The current study lacks a negative control group without the application of a membrane, which is one disadvantage of the study as the benefit from barrier membranes is currently not entirely clear.34 CONCLUSIONS Within the limitations of this preliminary study, it could be concluded that Bio-Ossâ Collagen and autogenous bone, each in combination with a resorbable membrane have a comparable effect on preservation of alveolar width after tooth extraction. Both grafts showed good biological compatibility. However, both techniques could not entirely prevent tissue volume loss in our limited number of patients. In regard to the necessity of a second surgical intervention for grafting with autogenous bone, the use of Bio-Ossâ Collagen may be advantageous when no second surgical intervention (e.g. third molar removal) is necessary as donor site morbidity could be prevented. © 2015 Australian Dental Association
0.4490 1.0000 1.0000 0.0052
ACKNOWLEDGEMENTS The authors are grateful to Henry Schein Deutschland GmbH, Langen, Germany, for providing the implants. Bio-Ossâ Collagen and Bio-Gideâ were donated by Geistlich Pharma AG, Wolhusen, Switzerland. The authors wish to thank Mrs Diana J€ unger for the technical assistance in preparing the histological sections. The authors declare they have no conflicts of interest.
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13. Hoppenreijs TJ, Nijdam ES, Freihofer HP. The chin as a donor site in early secondary osteoplasty: a retrospective clinical and radiological evaluation. J Craniomaxillofac Surg 1992;20: 119–124.
27. Araujo MG, Lindhe J. Socket grafting with the use of autologous bone: an experimental study in the dog. Clin Oral Implants Res 2011;22:9–13.
14. Nkenke E, Schultze-Mosgau S, Radespiel-Troger M, Kloss F, Neukam FW. Morbidity of harvesting of chin grafts: a prospective study. Clin Oral Implants Res 2001;12:495–502. 15. Wong RWK, Rabie ABM. Effect of bio-oss collagen and collagen matrix on bone formation. Open Biomed Eng J 2010;4:71–76. 16. Araujo MG, Linder E, Lindhe J. Bio-Oss collagen in the buccal gap at immediate implants: a 6-month study in the dog. Clin Oral Implants Res 2011;22:1–8. 17. Fickl S, Zuhr O, Wachtel H, Stappert CFJ, Stein JM, Hurzeler MB. Dimensional changes of the alveolar ridge contour after different socket preservation techniques. J Clin Periodontol 2008;35:906–913. 18. Heberer S, Al-Chawaf B, Hildebrand D, Nelson JJ, Nelson K. Histomorphometric analysis of extraction sockets augmented with Bio-Oss Collagen after a 6-week healing period: a prospective study. Clin Oral Implants Res 2008;19:1219–1225. 19. Donath K, Breuner G. A method for the study of undecalcified bones and teeth with attached soft tissues. The Sage-Schliff (sawing and grinding) technique. J Oral Pathol 1982;11:318–326. 20. Wood DL, Hoag PM, Donnenfeld OW, Rosenfeld LD. Alveolar crest reduction following full and partial thickness flaps. J Periodontol 1972;43:141–144. 21. Pearce AI, Richards RG, Milz S, Schneider E, Pearce SG. Animal models for implant biomaterial research in bone: a review. Eur Cell Mater 2007;13:1–10. 22. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing of human extraction sockets: 2. Histochemical observations at 9 months. J Periodontol 2001;72:152–159. 23. Lynch MP, Stein JL, Stein GS, Lian JB. The influence of type I collagen on the development and maintenance of the osteoblast phenotype in primary and passaged rat calvarial osteoblasts: modification of expression of genes supporting cell growth, adhesion, and extracellular matrix mineralization. Exp Cell Res 1995;216:35–45. 24. Cardaropoli G, Araujo M, Lindhe J. Dynamics of bone tissue formation in tooth extraction sites. An experimental study in dogs. J Clin Periodontol 2003;30:809–818.
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28. Lindhe J, Cecchinato D, Donati M, Tomasi C, Liljenberg B. Ridge preservation with the use of deproteinized bovine bone mineral. Clin Oral Implants Res 2014;25:786–790. 29. Calasans-Maia M, Resende R, Fernandes G, Calasans-Maia J, Alves AT, Granjeiro JM. A randomized controlled clinical trial to evaluate a new xenograft for alveolar socket preservation. Clin Oral Implants Res 2014;25:1125–1130. 30. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing of human extraction sockets. Part 1: histomorphometric evaluations at 9 months. J Periodontol 2000;71:1015–1023. 31. Araujo MG, da Silva JCC, de Mendonca AF, Lindhe J. Ridge alterations following grafting of fresh extraction sockets in man. A randomized clinical trial. Clin Oral Implants Res 2015;26:407–412. 32. Kirkland G, Greenwell H, Drisko C, Wittwer JW, Yancey J, Rebitski G. Hard tissue ridge augmentation using a resorbable membrane and a particulate graft without complete flap closure. Int J Periodontics Restorative Dent 2000;20:382–389. 33. Cordaro L, Torsello F, Morcavallo S, Di Torresanto VM. Effect of bovine bone and collagen membranes on healing of mandibular bone blocks: a prospective randomized controlled study. Clin Oral Implants Res 2011;22:1145–1150. 34. Horowitz R, Holtzclaw D, Rosen PS. A review on alveolar ridge preservation following tooth extraction. J Evid Based Dent Pract 2012;12:149–160.
Address for correspondence: Dr Matthias Schulz Department of Oral and Maxillofacial Surgery Faculty of Medicine ‘Carl Gustav Carus’ Technische Universit€at Dresden Fetscherstraße 74 D-01307 Dresden Germany Email: [email protected]
© 2015 Australian Dental Association
The official journal of the Australian Dental Association
Australian Dental Journal 2016; 61: 62–70 doi: 10.1111/adj.12313
Autogenous bone and a bovine bone substitute for ridge preservation: preliminary clinical and histologic findings MC Schulz,* MB Kallweit,† S Kallweit,† R Koch,‡ G Lauer,* R Mai,* T Hoffmann§ *Department of Oral and Maxillofacial Surgery, Faculty of Medicine ‘Carl Gustav Carus’, Technische Universit€at Dresden, Dresden, Germany. †Private Practice, Kirchberg, Germany. ‡Institute for Medical Informatics and Biometry, Faculty of Medicine ‘Carl Gustav Carus’, Technische Universit€at Dresden, Dresden, Germany. §Department of Periodontology, Faculty of Medicine ‘Carl Gustav Carus’, Technische Universit€at Dresden, Dresden, Germany.
ABSTRACT Background: Tooth extractions lead to morphological changes of the alveolar ridge. For oral rehabilitation sufficient bone volume of the alveolar ridge is required. This clinical study compared the ability of Bio-Ossâ Collagen to autogenous bone to preserve bone volume after tooth extraction. Methods: A total of 17 patients with 20 extraction sites were examined. After extraction, 10 sockets were each filled with either autogenous bone or Bio-Ossâ Collagen and covered with a resorbable membrane. The width of the alveolar ridge was measured postoperatively, and after 4 and 6 months respectively. Prior to implant insertion, a bone biopsy was taken from the grafted sites and evaluated histologically. Results: The width of the alveolar ridge in the Bio-Ossâ Collagen group decreased about 5.33 6.62% after 4 months and 9.45 10.51% after 6 months. The reduction in the group augmented with autogenous bone was 14.31 21.41% after 4 months and 19.17 8.38% after 6 months. No statistically significant differences were observed. The histological examination showed comparable area fractions of total bone in both groups (Bio-Ossâ Collagen: 59.99 24.23%; autogenous bone: 61.55 25.13%; p = 1.0). Conclusions: The present study demonstrated that autogenous bone and Bio-Ossâ Collagen are suitable for ridge preservation. However, both techniques could not entirely prevent tissue volume loss. Keywords: Autogenous bone, bone substitutes, clinical research, histology, wound healing. (Accepted for publication 22 March 2015.)
INTRODUCTION Tooth extractions lead to considerable changes in the height and width of the alveolar ridge. In a clinical study, Schropp et al. demonstrated that tooth extractions cause the loss of up to 50% of the alveolar width in the posterior regions.1 Two-thirds of this loss occurred in the first 3 months. In the aesthetic zone, a pronounced loss of buccal bone was observed after tooth extraction.2 Ara ujo and Lindhe found that the resorptive process is pronounced in the crestal area of the buccal alveolar wall.3 According to Horv ath et al., the reasons for these changes are periodontal diseases, periapical lesions, trauma and traumatic extraction methods.4 However, for oral rehabilitation a sufficient bone volume of the alveolar ridge is required, e.g. implant therapy would require bone dimensions of 6–7 mm.5 A pronounced loss of bone leads to difficulties in placing implants in a position suitable 62
for prosthodontic restoration.6 Different techniques have been evaluated to perform preservation of ridge preservation, such as barrier membranes, autogenous or xenogenous graft materials or combinations of these methods. The application of membranes has shown positive results for alveolar ridge protection. For guided tissue regeneration, they can be used either alone or in combination with bone substitutes.7,8 Membranes have a barrier function to prevent the ingrowth of connective tissue or epithelium in the extraction alveolus.9 This may support an uneventful healing of the extraction sites.10 In reconstructive surgery, autogenous bone grafts obtained from intraoral or extraoral grafting sites are considered the ‘gold standard’. Their main properties are osteogenicity, osteoinduction and a lack of immunogenicity.11 However, harvesting from intraoral sites might cause some discomfort. A second sur© 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone gery at the harvesting site is required with possible wound healing disturbances, swelling and bleeding.12 Furthermore, depending on the donor site, disturbances in the sensation of the skin of the chin, tongue and mucosa as well as negative pulpal sensitivity might occur.13,14 Therefore, various xenogenic and synthetic bone substitutes are available for bone grafting. Their advantages are unlimited availability and no need for a second surgical procedure. One of these xenogenous materials is Bio-Ossâ Collagen, which is obtained from deproteinized bovine bone. Wong and Rabie augmented a defect in the parietal bone of New Zealand rabbits with either collagen or the bovine bone substitute.15 They demonstrated a stimulation of bone formation. In another animal study, Bio-Ossâ Collagen was used to graft a buccal gap situation with satisfactory results.16 Ara ujo et al. demonstrated an enhanced volume of hard tissue in the crestal area of dental implants after grafting with the substitute.16 In an animal study by Fickl et al., Bio-Ossâ Collagen showed a preventive effect of volume loss in extraction sites.17 Heberer et al. found histological indeterminate results of bone formation in human extraction sockets after a healing period of 6 weeks when augmented with bovine bone.18 The sites showed a range from prevalent provisional matrix to matured bone similar to healing periods up to 3 months. However, there might be a higher risk of delayed healing when using grafting materials.6 The objective of the present study was to examine the volume stability and histological behaviour of BioOssâ Collagen and autogenous bone in combination with the Bio-Gideâ membrane. It was hypothesized that Bio-Ossâ Collagen in combination with a resorbable membrane could preserve more volume compared to autogenous bone in a clinical situation. Thus, a sufficient preservation of bone volume for implant placement would be possible without any donor site morbidity.
Eleven molars, 6 premolars and 3 incisors were extracted. Indications for tooth extraction were nontreatable endodontic lesions (11 teeth), extensive caries lesions (6 teeth) and longitudinal fractures (3 teeth). The inclusion and exclusion criteria are listed in Table 1. The patients were assigned to a treatment group according to the necessity of a second surgical intervention to harvest autogenous bone, e.g. the operative removal of a wisdom tooth. For periodontal screening, probing depth according to the periodontal screening index, approximal plaque index and sulcus bleeding index were recorded. All patients received professional tooth cleaning and showed no signs of inflammation (swelling, bleeding on probing) prior to extractions. Materials Commercially available blocks of Bio-Ossâ Collagen (Geistlich Pharma AG, Wolhusen, Switzerland) were used as a bone substitute. The material consists of spongious, deproteinized, bovine bone containing 10% collagen type I. The blocks were adapted to the extraction socket by cutting prior to insertion. The Bio-Gideâ membrane (Geistlich Pharma AG, Wolhusen, Switzerland) was used to cover the alveolus. The resorbable membrane of 25 mm 9 25 mm consisted of porcine collagen type I. The autogenous bone was obtained from the posterior mandible using piezo surgery (Piezosurgeryâ, mectron Deutschland Vertriebs GmbH, K€ oln, Germany). To reduce patient inconvenience, the intervention was performed in the context of an operative removal of the third molar. The patient’s own blood was collected from the defect using a syringe. Combined cortical and spongious bone blocks of 15 mm 9 10 mm 9 10 mm were ground in a bone mill. The bone was stored in the patient’s own blood until insertion into the socket.
MATERIALS AND METHODS This clinical study was undertaken in accordance with the Declaration of Helsinki on medical protocols and ethics involving human subjects. The trial was prospective, non-randomized, non-blinded and performed in a private practice. The study was approved by the Ethical Review Board of the University of Freiburg, Germany (08/1210). All patients provided written consent for participation in the study. Patient selection Seventeen patients (average age: 47.2 years, range 28– 59 years; 11 female, 6 male) with 20 extraction sites (maxilla: 13 teeth; mandible: 7 teeth) were evaluated. © 2015 Australian Dental Association
Table 1. Inclusion and exclusion criteria for selected patients Inclusion criteria - patients aged over 18 years - good oral hygiene - at least one adjacent tooth to extraction socket - alveolus bordered by four bony walls after extraction
Exclusion criteria - pregnancy or lactation - loss of the buccal bone wall - residual bone height less than 4 mm - smoking of more than 10 cigarettes per day - alcohol or drug abuse - rheumatism - poorly regulated diabetes - systemic bone diseases or any condition of compromised immune status 63
MC Schulz et al. Clinical procedures Prior to extraction, impressions of the jaw were taken and individual plaster casts were produced. Splints for standardized measuring were manufactured. Bone mapping was performed directly following extraction, after 4 and 6 months (prior to implant insertion). Therefore, 6 vertical rows of each 5 measuring points were set per tooth – 3 lingual and 3 buccal: mesial, median, distal (Fig. 1). The cervical measuring points were set at 2 mm below the gingival margin. The distance between the measuring points was 2 mm respectively. Thus, the alveolar width was measured after administration of local anaesthesia (Ubistesinâ 1:100,000; 3M Deutschland, Neuss, Germany) and the surgical procedures carried out by one experienced surgeon. The thickness of the mucosa was measured using a graded probe penetrating the gingiva orthogonally to the bone. A metal stop was used to mark the penetration depth of the probe. The stop was fixed into position and after measuring, each value was transferred to the plaster cast by marking the penetration depth. The extractions were performed atraumatically using a scalpel and a periotom. Multirooted teeth were hemi- or trisectioned before extraction. After careful debridement, the socket was clinically inspected using a dental probe to ensure that all four bony walls were intact. If no mobility or fenestration of the bony walls was detected by probing, the alveolus was filled to the margin with Bio-Ossâ Collagen or autogenous bone respectively. Care was taken to ensure that the Bio-Ossâ Collagen was saturated with blood. To cover the material, a Bio-Gideâ membrane was fixed in a double layer without undermining the adjacent mucosa using two mattress sutures with Seralonâ (Serag-Wiessner KG, Naila, Germany). The wound was allowed to heal by secondary intention. For postoperative analgesia and prevention of inflammation, the patients received 2 9 600 mg ibuprofen per day for 2 days (Aliudâ Pharma GmbH, Laichingen, Germany). From the second day after extraction, the patients used Chlorhexamed fluid 0.1% (GlaxoSmithKline Consumer
Healthcare GmbH & Co. KG, B€ uhl, Germany) for plaque control. Follow-up care was performed on day 1, 4 and 7 postoperative. The sutures were removed after 7 days. Four and 6 months after extraction (14 days), bone mapping measurements were repeated analogically to the first time point. The splints were lined with Honigum light (DMG Chemisch-Pharmazeutische Fabrik GmbH, Hamburg, Germany) to reproduce the current profile of the alveolar ridge. Plaster casts were then manufactured. Six months after extraction, the implant insertion was undertaken with local anaesthesia. A crestal incision was made and the mucoperiosteal flap elevated to expose the implant site. A bone biopsy of the centre of the extraction socket was obtained using the drilling core of a trephine burr with an inside diameter of 2 mm and a length of 5 mm (DIT Diamanttechnik GmbH & Co. KG, Oberlungwitz, Germany). Implant insertion (alphatecâ BONITexâ surface, Henry Schein Deutschland GmbH, Langen, Germany) using burrs and osteotomes then followed. All implants could be placed without additional augmentation. The mucoperiosteal flap was repositioned and fixed with mattress sutures using Seralonâ. The wounds were allowed to heal by primary intention. Postoperative treatment was carried out identically to that following the extractions. Dynamic profile of the alveolar ridge After lining the measuring splint, three plaster casts of each site were manufactured. The casts were cut in an orobuccal direction at each measuring row and values were transferred on the sections (Fig. 2). Thus, three sections per site and time point were obtained. The thickness of the mucosa was marked along the measuring rows on each section using the probe with the metal stop indicating the penetration depth. By linking the marked points, the hard tissue profile could be transferred onto the sections. Subsequently, the sections were scanned and the width of the alveolar crest was measured. Histological preparation and examination
Fig. 1 Splint for standardized measuring on cast model. Three rows (mesial, median, distal) of each 5 measuring points are located on the buccal and oral site. 64
After dehydration in a graded series of ethanol, all drill cores were removed from the trephine burr and embedded in methylmethacrylate (Technovitâ 9100 NEU, Heraeus Kulzer, Wehrheim, Germany). 500 lm thick axial sections in an orobuccal direction of each specimen were cut with a diamond saw system (Exaktâ–Mikro–Schleifsystem; Exakt-Apparatebau, Norderstedt, Germany) according to Donath’s microsectioning and grinding technique.19 The axialsectional thickness was reduced to 50 lm using a roll © 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone The histological evaluation focused on potentially inflammatory reactions and on the qualitative evaluation of bone formation. For histomorphometrical analysis, the whole area of the drill core was used. The amount of mature and immature bone, stromal tissue and remaining bone substitute was quantified. Therefore, the appropriate area fractions were detected semi-automatically by tracing the contours of the structures and measuring the corresponding areas. Mature and immature bone was distinguished by the microscopical structure. Subsequently, the ratios of mature and immature bone, stromal tissue and remaining bone substitute to the complete area of the drill core were calculated. Statistical analysis Statistical software SAS (SAS Institute Inc., Cary, NC, USA) was used for all analyses. The mean values and standard deviations of the alveolar width were calculated. Statistical analysis was performed using linear models of covariance analysis for repeated measures. The treatment group was set up as a test factor and the baseline value served as quantitative covariable. A compound symmetry was assumed for the covariance structure of the time points. A Tukey-adjusted test procedure was used to compare the adjusted means. For histological measurements, the ratios of bone, residuals of Bio-Ossâ Collagen and stroma were calculated. Comparisons of the mean values were performed using non-parametrical U–tests. The level of statistical significance was set at a = 0.05. RESULTS Clinical results
Fig. 2 Cast sections of the alveolar ridge profile at extraction sites. (a) The black dots indicate the measuring points for the hard tissue profile. (b) The fractions of hard (blue) and soft tissue (red) are calculated by colour labelling.
grinder containing sandpaper with decreasing grain size (Exakt-Apparatebau, Norderstedt, Germany). Subsequently, the specimens were stained with Masson-Goldner staining. The whole drill core was imaged parallel to the length axis in an orobuccal direction using light microscopy (Olympus BX61, Olympus Deutschland GmbH, Hamburg, Germany). Multiple image alignment was possible, using an automatic scanning table (L-Step 12/2, M€ arzh€ auser, Wetzlar, Germany). Nine images per sample were scanned under 10-fold magnification and fused to one image. © 2015 Australian Dental Association
All 17 patients completed the study. Two patients (1 Bio-Ossâ Collagen; 1 autogenous bone) suffered from mild inflammation following tooth extraction, which was easily treated with a local application of Chlorhexamed fluid for 5 days. No surgical revision was necessary. The soft tissue coverage on postoperative day 1 and 4 was uneventful in all patients. Thus, removal of the sutures was possible after 7 days. After 6 months, the profile of the alveolar ridge appeared concavely in horizontal and vertical dimensions. At the donor site, no wound healing disturbances occurred. No affection of the mandibular nerve was observed. Dynamic profile of the alveolar ridge After 4 and 6 months, there was a noticeable reduction of alveolar width for both methods used. This reduction was more pronounced after 6 months than after 4 months. The crestal part of the extraction 65
MC Schulz et al. socket was affected more than the apical part. The loss of alveolar width was slightly higher in the group grafted with autogenous bone. This reduction was more pronounced after 6 months than after 4 months. The metric data are shown in Table 2 and the percentages in Table 3. The loss of alveolar width for both groups was not statistically significant after 4 and 6 months (p = 0.0745 for both time points). The buccal lamella was affected more when compared to the oral one, demonstrated by a concave vestibular profile of the ridge. The highest decrease was observed in the posterior maxilla. Extraction sites in the mandible premolar region showed the lowest reduction. The differences observed between both groups were not statistically significant (p = 0.4556).
woven bone. Signs of inflammation or osteolysis could not be observed. In biopsies following grafting with autogenous bone, maturation of bone was more pronounced compared to Bio-Ossâ Collagen. A dense meshwork of trabecular bone could be observed in the apical area of the samples. Areas of woven bone and stromal tissue were less pronounced compared to Bio-Ossâ Collagen. No signs of inflammation could be detected (Fig. 3a and 3b). Histomorphometry Histomorphometrical results showed comparable areas of bone and stroma in both groups. No statistically significant differences could be observed. Almost no remnants of Bio-Ossâ were detected. Details are shown in Table 4.
Histomorphology After 6 months of healing, sites filled with Bio-Ossâ Collagen showed a spongious trabecular meshwork of mature bone. A layer of woven bone covered the trabeculae, indicating new bone formation. Large areas of stromal tissue could be found between the trabeculae over the entire sample. The few remaining parts of Bio-Ossâ Collagen were integrated in formations of
DISCUSSION The present study compared the volume stability and histological behaviour of Bio-Ossâ Collagen to autogenous bone in a clinical situation. Therefore, the dynamic profile of the alveolar ridge was examined
Table 2. Reduction of the alveolar ridge width in millimetres for each region measured after 4 and 6 months (mean values of each vertical measuring row) BioOssâ Collagen Reduction in mm mesial Region 35 17 25 16 44 16 26 47 26 23
4 months 0.3 0.6 1.5 1.4 0.3 1.3 0.6 0.5 0.4 0.5
median 6 months 0.3 1.3 2.4 1.9 0.9 2.0 1.0 0.9 0.8 1.2
4 months 0.4 0.4 0.5 0.9 0.2 0.9 0.8 0.5 0.3 0.4
distal 6 months 0.8 0.5 0.9 1.4 0.5 1.1 1.5 1.0 0.8 0.5
4 months 0.1 0.9 0.8 1.0 0.2 0.5 1.0 0.6 0.3 0
6 months 0.3 1.0 1.3 1.2 0.4 1.1 1.5 1.1 0.5 0
Autogenous bone Reduction in mm mesial Region 46 14 36 16 34 11 26 25 12 36 66
4 months 3.1 0.5 0.5 0.8 0.3 0.5 0.6 0.4 0.6 2.4
median 6 months 3.1 1.3 2.1 1.3 0.6 0.8 0.8 1.0 1.1 2.6
4 months 2.6 0.3 0.8 1–1 0.3 0.5 0.2 0.6 0.4 2.5
distal 6 months 2.8 0.8 1.9 1.6 0.8 0.9 0.8 0.9 0.8 2.9
4 months 2.5 0.6 0.5 0.9 0.1 0.3 0.4 1.3 0.6 2.5
6 months 2.6 0.6 1.2 1.1 0.3 0.6 0.8 1.5 0.8 2.8
© 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone Table 3. Decrease of alveolar width for both groups after 4 and 6 months in percentage terms with standard deviations Bio-Ossâ Collagen
Time mesial 4 months 6 months
7.18 8.52 12.47 11.63
median 5.33 6.62 9.45 10.51
autogenous bone distal 5.42 7.64 8.97 11.17
immediately post extraction, and after 4 and 6 months. Bone biopsies were taken after 6 months, prior to implant insertion. One limitation of the study was the small number of patients and the lack of a control group without any augmentation. The clinical results demonstrated that extraction sites grafted with Bio-Ossâ Collagen showed a slight decrease of the width of the alveolar ridge after 6 months. Iasella et al. found similar results in a clinical study after 4 and 6 months.8 A decrease of 1.2 0.9 mm in horizontal width in the middle of the alveolar ridge for the preservation group was observed which is comparable to the 1.24 1.14 mm found in the present study. Compared to non-grafted extraction sockets, their differences were statistically significant. A resorption of the buccal lamella was also observed.8 The buccal part of the socket mainly consists of bundle bone in which the Sharpey’s fibres are fixed. Caused by the tooth extraction, the Sharpey’s fibres are removed and the bundle bone loses its function. During the remodelling process, it is degraded by osteoclasts. Another factor which might influence the extent of resorption is the thickness of the buccal lamella. In the present study, only sockets with intact bony walls were included. This was proved by sounding with a probe. However, the thickness of the buccal lamella was not measured intraoperatively. Another limiting factor of the study is the inclusion of single- and multi-rooted teeth. Schropp et al. stated that ridge reduction in percentage terms was lower in the premolar region compared to the molar region.1 Thus, the effects of ridge preservation after extraction of multi-rooted teeth might be more pronounced than after extraction of single-rooted teeth. However, in the anterior maxilla bone loss occurring after extraction of single-rooted teeth is expected to be higher than in the premolar and molar region.2 Thus, the current study includes a heterogeneous sampling collective. Furthermore, the elevation of a mucoperiostal flap might cause bone resorption up to 1 mm.20 Therefore, to prevent bone loss in the present study tooth extractions were performed without flap elevation. Animal studies could support these findings. Fickl et al. observed the lowest volume loss for sockets grafted with Bio-Ossâ Collagen in a study of dogs.17 The metric decrease after 2 and 4 months was -1.3 0.2 mm and -1.5 0.2 mm respectively. © 2015 Australian Dental Association
mesial 12.09 25.35 17.17 25.08
median 9.27 21.08 14.31 21.41
distal 10.07 21.29 12.93 21.50
These findings are comparable to the results of the present study. However, the higher bone turnover rate in canines has to be considered.21 Furthermore, our data are supported by the results of Araujo and Lindhe who also observed a pronounced resorption of the buccal lamella in an experimental study of dogs.3 A possible reason for this resorption might be the loss of bundle bone. Histomorphological results of the present study showed a pronounced ratio of lamellar bone in sockets filled with autogenous bone. In sites grafted mostly with Bio-Ossâ Collagen, a direct contact of woven bone to remnants of the substitute were observed after 6 months of healing. This is in agreement with Artzi et al. who found a pronounced deposit of woven bone in sockets filled with pure Bio-Ossâ granules after 9 months of healing.22 The greater amount of Bio-Oss particles may be due to different reasons. On the one hand, a denser packing could be achieved with pure Bio-Ossâ particles. This potentially delays the ingrowth of blood vessels and thus might hamper resorption. Furthermore, by using Bio-Ossâ in combination with collagen I, bone remodelling might be accelerated due to an enhancing effect of collagen I on bone metabolism.23 In animal studies, the results of the present study could be supported. Cardaropoli et al. observed granules of Bio-Ossâ Collagen embedded in woven bone structures after 3 months.24 These findings indicate good biocompatibility, demonstrating no fibrous reaction or inflammation. Furthermore, a higher ratio of lamellar bone in sockets grafted with autogenous bone compared to sites filled with BioOssâ Collagen was found in the present study. While lamellar bone represents a mature form of bone, woven bone represents a stage of the membranous ossification process. Autogenous bone has osseoinductive properties due to the fact that it contains bone morphogenic proteins which are able to change mesenchymal cells into osteogenic cells.25 In contrast, Bio-Ossâ Collagen has to be considered as osseoconductive. Its porous structure provides a scaffold for migrating bone cells and fostering their differentiation.26 Bone formation in areas grafted with Bio-Ossâ might be decelerated as resorption of Bio-Oss granules seems to be a long-lasting process. In the present study, these findings could be supported. The ratio of mature and immature bone in the different sites 67
MC Schulz et al.
Fig. 3 Histological sections. (a) shows a loose meshwork of trabecular bone (tb) and a large area of stromal tissue (s) over the entire biopsy from the crest (top) to the apical part (bottom). Only few remaining BioOssâ particles could be found (b). (b) Compared to biopsies obtained from sockets grafted with Bio-Oss, this picture shows an area of trabecular bone (tb) in the apical region of the biopsy (bottom). In the direction to the crest (top), the meshwork is wider, large areas of stromal tissue (s) can be found. Masson-Goldner-staining, magnification 1:10. 68
indicate that healing in the sockets grafted with BioOssâ Collagen is slightly delayed compared to autogenous bone. Our findings support those made by Arajo and Lindhe in a study of beagle dogs.27 After u 3 months of healing, higher ratios of mineralized bone were observed in sites containing autogenous bone compared to sockets grafted with the bovine bone substitute. However, the value of autogenous bone for ridge preservation is not clear. Their study indicated that autogenous bone chips had no preventive effect on bone resorption. This is in agreement with the present study, where autogenous bone had an enhancing effect on bone healing and maturation, but no preventive effect on ridge dimensions after tooth extractions. Due to the almost unavoidable resorption of the buccal lamella, both autogenous bone and Bio-Ossâ Collagen seem to serve as a space holder in the socket. Histomorphometric findings in the present study showed comparable amounts of bone and stromal tissue for both methods. An unexpected finding in our study was the small amount of remaining Bio-Ossâ particles detected after 6 months, as other groups observed higher amounts of Bio-Ossâ. In a clinical study, Heberer et al. found 27 7.2% of Bio-Ossâ Collagen after 6 weeks of healing.18 One reason for this might be the different healing times. Resorption of Bio-Ossâ Collagen particles after 6 months might be more advanced than after 6 weeks. However, Bio-Ossâ Collagen is typically not resorbed after 6 months. Lindhe et al. observed 19.0 6.5% of substitute particles still present after 6 months.28 When pure Bio-Ossâ was used in extraction sockets fractions of remnants were between 22.6 7.9% after 6 months and still 30.8 7.8% after 9 months.29,30 One reason for this might be the use of pure Bio-Ossâ without the addition of collagen I. The main part of the organic bone components is known to stimulate bone cell activities and therefore enhance bone metabolism.23 Therefore, the resorption of the Bio-Ossâ granules might be decelerated compared to Bio-Ossâ Collagen. Another reason might be the site the drill core was obtained from. When the drill core was harvested from the region of the interradicular septum, no large amounts of remnants of the bone substitute were to be expected. In the present study, a membrane has been used for both groups. The barrier prevents the ingrowth of connective tissue and epithelium into the extraction sockets. The membrane was used in a double layer to allow the healing in secondary intention. Thus, a sufficient stability was achieved over the soft tissue healing period. Other studies used a patch of oral mucosa to cover the augmented site.31 This might be advantageous for enhanced healing without graft exposure. On the other hand, another donor site for harvesting the mucosa is necessary. By solely using membranes and healing by secondary intention, wound dehiscence may occur. One © 2015 Australian Dental Association
Ridge preservation with autogenous and bovine bone Table 4. Area fractions of the histological sections of bone, stroma and remnants of Bio-Ossâ Collagen with their standard deviations (SD), minimum (Min), maximum (Max) in percentage terms and p-values Area fraction
Group
Mean
SD
Min
Max
p
Mature bone
Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone Bio-Ossâ Collagen Autogenous bone
41.39 51.35 18.60 10.21 59.99 61.55 39.89 38.45 0.36 –
18.43 25.96 22.90 12.57 24.23 25.13 24.06 25.13 0.46 –
16.66 20.05 0.00 0.00 23.62 24.60 5.87 4.28 0.00 –
69.05 94.33 51.25 32.65 94.13 95.72 76.38 75.40 1.32 –
0.4057
Immature bone Bone total Stroma Bio-Ossâ
reason for wound healing disturbances might be the reduced blood supply in an elevated flap which is separated from the underlying bone by a membrane.32 Furthermore, a reduction of bone volume in the augmented area might occur using membranes due to membrane exposure.7 This was not observed in the present study. This finding might be due to the fact that Lekovic elevated full thickness flaps which could lead to bone resorption. Certainly, the thin buccal lamella would be affected by this resorption by up to 1 mm.20 In the present study, tooth extraction and augmentation were performed without elevation mucoperiosteal flaps. Cordaro et al. observed slightly more wound healing disturbances when augmenting atrophic ridge sites with bone blocks and Bio-Ossâ covered with a Bio-Gideâ membrane.33 Similar observations were not made in our study. No dehiscences or signs of inflammation or infection occurred, neither clinically nor histologically. Compared to our study, the augmented sites were not fully covered by bone. This could lead to tension in the covering soft tissue causing dehiscences. The current study lacks a negative control group without the application of a membrane, which is one disadvantage of the study as the benefit from barrier membranes is currently not entirely clear.34 CONCLUSIONS Within the limitations of this preliminary study, it could be concluded that Bio-Ossâ Collagen and autogenous bone, each in combination with a resorbable membrane have a comparable effect on preservation of alveolar width after tooth extraction. Both grafts showed good biological compatibility. However, both techniques could not entirely prevent tissue volume loss in our limited number of patients. In regard to the necessity of a second surgical intervention for grafting with autogenous bone, the use of Bio-Ossâ Collagen may be advantageous when no second surgical intervention (e.g. third molar removal) is necessary as donor site morbidity could be prevented. © 2015 Australian Dental Association
0.4490 1.0000 1.0000 0.0052
ACKNOWLEDGEMENTS The authors are grateful to Henry Schein Deutschland GmbH, Langen, Germany, for providing the implants. Bio-Ossâ Collagen and Bio-Gideâ were donated by Geistlich Pharma AG, Wolhusen, Switzerland. The authors wish to thank Mrs Diana J€ unger for the technical assistance in preparing the histological sections. The authors declare they have no conflicts of interest.
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Address for correspondence: Dr Matthias Schulz Department of Oral and Maxillofacial Surgery Faculty of Medicine ‘Carl Gustav Carus’ Technische Universit€at Dresden Fetscherstraße 74 D-01307 Dresden Germany Email: [email protected]
© 2015 Australian Dental Association
