Guided bone generation in a rabbit mandible model after periosteal expansion with an osmotic tissue expander

Objectives: To evaluate the space‐maintaining capacity of titanium mesh covered by a collagen membrane after soft tissue expansion on the lateral border of the mandible in rabbits, and to assess bone quantity and quality using autogenous particulate bone or bone‐substitute (Bio‐Oss^®), and if soft tissue ingrowth can be avoided by covering the mesh with a collagen membrane. Material and methods: In 11 rabbits, a self‐inflatable soft tissue expander was placed under the lateral mandibular periosteum via an extra‐oral approach. After 2 weeks, the expanders were removed and a particulated onlay bone graft and deproteinized bovine bone mineral (DBBM) (Bio‐Oss^®) were placed in the expanded area and covered by a titanium mesh. The bone and DBBM were separated in two compartments under the mesh with a collagen membrane in between. The mesh was then covered with a collagen membrane. After 3 months, the animals were sacrificed and specimens were collected for histology. Results: The osmotic soft tissue expander created a subperiosteal pocket and a ridge of new bone formed at the edges of the expanded periosteum in all sites. After the healing period of 3 months, no soft tissue dehiscence was recorded. The mean bone fill was 58.1±18% in the bone grafted area and 56.9±13.7% in the DBBM area. There was no significant difference between the autologous bone graft and the DDBM under the titanium mesh with regard to the total bone area or the mineralized bone area. Scanning electron microscopy showed that new bone was growing in direct contact with the DBBM particles and the titanium mesh. There is a soft tissue ingrowth even after soft tissue expansion and protection of the titanium mesh with a collagen membrane. Conclusion: This study confirms that an osmotic soft tissue expander creates a surplus of periosteum and soft tissue, and that new bone can subsequently be generated under a titanium mesh with the use of an autologous bone graft or DBBM. To cite this article:
Abrahamsson P, Isaksson S, Andersson G. Guided bone generation in a rabbit mandible model after periosteal expansion with an osmotic tissue expander.
Clin. Oral Impl. Res. 22 , 2011; 1282–1288.
doi: 10.1111/j.1600‐0501.2010.02108.x     

Intra-oral soft tissue expansion and volume stability of onlay bone grafts

Insufficient regeneration of missing bone and soft-tissue may present aesthetic or functional problems in patients indicated for dental implant surgery. Several techniques such as bone grafts, bone substitutes and guided tissue regeneration (GTR) have been described to rebuild a compromised alveolar ridge. Adequate soft-tissue coverage of grafted bone and titanium-mesh is important to avoid exposure which may result in loss of the bone graft. The general aim of this thesis was to evaluate use of an osmotic tissue expander for expanding intra-oral soft tissue--creating a surplus of soft tissue-- in preparation for onlay bone grafting. An experimental rabbit model was used in studies (I), (II) and (III). In (I) an osmotic soft-tissue expander was placed bilaterally on the lateral wall of the mandible via an extra-oral approach. After two weeks of expansion the rabbits were killed and specimens were collected for histology. No inflammatory reaction and no resorbtion of the cortical bone occured. The periosteum was expanded and new bone formation was seen in the edges of the expander. In (II) and (III) the expander was placed under the periosteum in the same way as in (I): bilaterally in 13 rabbits in (II) and unilaterally in 11 rabbits in (III). After two weeks of expansion the expander was identified and removed. In (II) particulated bone was placed at the recipient site protected by a titanium mesh in one site and a bio-resorbable mesh on the other site. In (III), DBBM particles and bone particles collected from the lateral border of the mandible separated by a collagen membrane was placed at the recipient site. The graft was protected by a pre-bent titanium mesh covered by a collagen membrane. After a healing period of 3 months specimens were collected for histological and SEM examination. New bone was growing in direct contact with the titanium mesh and bio resorbable mesh. The newly formed bone had the same calcium content as the mature bone in the base of the mandible. In the clinical study (IV) 20 patients were consecutively recruited and randomised into two groups. The experimental group (ten patients) had an osmotic soft tissue expander implanted. After two weeks of expansion the expander was removed and a particulated bone graft protected by a titanium mesh and a collagen membrane was fixed to the recipient site. Titanium implants were installed after a healing period of 6 months. The patients in the reference group had a bone block grafted from the anterior ramus fixated to the recipient site with one or two titanium mini screws. Implants were installed after a healing period of 6 months. A three dimensional optical measuring device was used to measure alterations in the soft tissue profile before each surgical procedure. The three-dimensional changes were then analysed on a PC. The results from the clinical study in patients confirmed the results from the experimental rabbit studies. The osmotic tissue expander expanded the soft tissue. Expander perforations of the soft tissue occurred in two patients. The optical measurements demonstrated a positive volume gain after soft tissue expansion and bone grafting. The expanded tissue could be used to cover a bone graft. There still was a risk of mesh exposure, even after soft tissue expansion, which occurred in two patients. In both groups, implants could be installed in the grafted bone in positions that would allow the crowns to fit aesthetically into the dental arch.     

骨膜牵张成骨的实验研究

目的　建立骨膜牵张成骨模型 ,探讨骨膜牵张成骨新技术 ,为牙槽骨缺损及其他骨缺损寻找新的修复方法。方法　将自制骨膜牵张成骨装置及钛网植入 12只成年兔的一侧下颌升支外侧面 ,从术后第 7天开始牵张 ,第 1次牵拉 2mm ,后每 3d牵拉 1mm ,共牵拉 15d ,最终将钛网牵拉离开骨面 7mm。术后第 2 8、35、4 2、5 6天分别处死 3只动物 ,进行组织计量学、X线片及组织学观察。结果　所有标本在计量学及X线片上均显示有新骨形成 ,术后第 2 8、35、4 2和 5 6天形成的新骨厚度平均分别为 (1 90± 0 13)mm、(2 2 2± 0 30 )mm、(3 17± 0 14 )mm和 (4 5 6± 0 4 6 )mm。组织学观察显示了新形成骨在成骨细胞数量上的增长 ,以及胶原纤维排列方向上的变化。结论　骨膜牵张法可以形成新骨 ,用于增加骨量。     

Bone augmentation after soft‐tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration

Objectives: The success of bone augmentation, for example of the alveolar ridge, might be endangered by dehiscence of the soft tissue that covers the augmented bone. Soft‐tissue coverage can be achieved without tension through pre‐augmentation tissue expansion with hydrogel expanders. We used a periosteal chamber to study the influence of tissue expansion on microcirculation and osseointegration in an in vivo animal model. Material and methods: Sixteen isogeneic Lewis rats were randomised into two groups. Additional eight animals served as donors of isogeneic bone grafts (Group 3, n=8). The bone grafts were harvested and implanted into Group 1 animals (n=8) (without tissue expansion) and Group 2 animals (after tissue expansion). In Group 2 (n=8), hydrogel expanders were inserted subperiosteally at the site to be augmented for 21 days. We used intravital microscopy to monitor microcirculation in vivo for 19 days after implantation. Specimens from both groups were evaluated histologically. Results: During the entire study period, functional microvessel density in the region above the augmentation material was significantly higher after previous tissue expansion (P>0.05). Both groups showed physiological microcirculation around the augmentation material. Histology revealed bone osseointegration of the bone graft in the group with tissue expansion and the presence of connective and granulation tissue in the group without tissue expansion. Conclusions: Pre‐augmentation soft‐tissue expansion with hydrogel expanders leads to higher functional microvessel density in the tissue above the augmentation material and thus, to more rapid osseointegration. The use of hydrogel expanders appears to increase the probability of success, especially of pre‐implant bone augmentation. To cite this article:
von See C, Gellrich N‐C, Jachmann U, Laschke MW, Bormann KH, Rücker M. Bone augmentation after soft‐tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration.
Clin. Oral Impl. Res. 21 , 2010; 842–847
doi: 10.1111/j.1600‐0501.2009.01847.x     

Expanding soft tissue with Osmed® tissue expanders in the goat maxilla

Objectives: Soft tissue limitations are encountered in implant dentistry, due to the loss of alveolar bone. The aim of this study is to compare the outcome of soft tissue preparation using Osmed^® self‐inflating soft tissue expanders with different in situ times in two implantation techniques. Material and methods: Osmed^® self‐inflating soft tissue expanders were implanted in goats using a tunnel approach and a flap approach. The animals were sacrificed after 1 h (controls) and 40 days (treated). A tattoo technique for stereographic measurements was used to look for soft tissue surface gain. Histological and histomorphometric analyses were performed to quantify and compare the changes in soft tissue volume and bone volume after 1 h and 40 days of implantation. Results: After 40 days, the expansion was visible and none of the goats had shown any inflammation. The space between the soft tissue and the bone was filled by the completely expanded expander and surrounding connective tissue. Between the test groups and the control groups, there was no histological difference in the structure of the soft tissue. Conclusions: All the tissue expanders expanded to their maximum size (2.8 times) and were a reliable product for creating a space between soft tissue and bone. The overlying soft tissue remained in excellent shape. There was no difference in the soft tissue volume and the bone volume between the tunnel and the flap approach after 40 days. To cite this article:
Uijlenbroek HJJ, Liu Y, He JF, Visscher C, van Waas MAJ, Wismeyer D. Expanding soft tissue with Osmed^® tissue expanders in the goat maxilla
Clin. Oral Impl. Res 22 , 2011; 121–128.
doi: 10.1111/j.1600‐0501.2010.01972.x     

Influence of various implant platform configurations on peri-implant tissue dimensions: an experimental study in dog

Aim: To evaluate the influence (i) of various implant platform configurations and (ii) of implant surface characteristics on peri‐implant tissue dimensions in a dog model. Material and methods: Mandibular premolars and first molars were extracted bilaterally in six Labrador dogs. After 3 months of healing, two implants, one with a turned and a second with a moderately rough surface, were installed on each side of the mandible in the premolar region. On the right side of the mandible, implants with a tapered and enlarged platform were used, while standard cylindrical implants were installed in the left side of the mandible. Abutments with the diameter of the cylindrical implants were used resulting in a mismatch of 0.25 mm at the tapered implant sites. The flaps were sutured to allow a non‐submerged healing. After 4 months, the animals were sacrificed and ground sections were obtained for histometric assessment. Results: All implants were completely osseointegrated. A minimal buccal bone resorption was observed for both implant configurations and surface topographies. Considering the animals as the statistical unit, no significant differences were found at the buccal aspect in relation to bone levels and soft tissue dimensions. The surface topographies did not influence the outcomes either. Conclusions: The present study failed to show differences in peri‐implant tissue dimensions when a mismatch of 0.25 mm from a tapered platform to an abutment was applied. The surface topographies influence a neither marginal bone resorption or peri‐implant soft tissue dimension. To cite this article:
Baffone GM, Botticelli D, Pantani F, Cardoso LC, Schweikert MT, Lang NP. Influence of various implant platform configurations on peri‐implant tissue dimensions: an experimental study in dog.
Clin. Oral Impl. Res. 22 , 2011; 438–444.     

Enhancing bone formation by transplantation of a scaffold-free tissue-engineered periosteum in a rabbit model

Objectives: The periosteum plays an important role in bone regeneration. However, the harvesting of autogenous periosteum is associated with disadvantages such as donor site morbidity and limited donor sources. This study uses an osteogenic predifferentiated cell sheet to fabricate a scaffold‐free tissue‐engineered periosteum (TEP). Material and methods: We generated an osteogenic predifferentiated cell sheet from rabbit bone marrow stromal cells (BMSCs) using a continuous culture system and harvested it using a scraping technique. Then, the in vitro characterization of the sheet was investigated using microscopy investigation, quantitative analysis of alkaline phosphatase (ALP) activity, and RT‐PCR. Next, we demonstrated the in vivo osteogenic potential of the engineered sheet in ectopic sites together with a porous β‐tricalcium phosphate ceramic. Finally, we evaluated its efficiency in treating delayed fracture healing after wrapping the cell sheet around the mandible in a rabbit model. Results: The engineered periosteum showed sporadic mineralized nodules, elevated ALP activity, and up‐regulated gene expression of osteogenic markers. After implantation in the subcutaneous pockets of the donor rabbits, the in vivo bone‐forming capability of the engineered periosteum was confirmed by histological examinations. Additionally, when wrapping the engineered periosteum around a mandibular fracture gap, we observed improved bone healing and reduced amounts of fibrous tissue at the fracture site. Conclusion: The osteogenic predifferentiated BMSC sheet can act as a scaffold‐free TEP to facilitate bone regeneration. Hence, our study provides a promising strategy for enhancing bone regeneration in clinical settings. To cite this article:
Ma D, Yao H, Tian W, Chen F, Liu Y, Mao T, Ren L. Enhancing bone formation by transplantation of a scaffold‐free tissue‐engineered periosteum in a rabbit model.
Clin. Oral Impl. Res. 22 , 2011; 1193–1199.
doi: 10.1111/j.1600‐0501.2010.02091.x     

Bone reaction adjacent to microplasma-sprayed calcium phosphate-coated oral implants subjected to an occlusal load, an experimental study in the dog

Background: A new microplasma spraying equipment (MSE) to deposit calcium phosphate (CaP) ceramic coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the low heat power of the microplasma jet, overheating of the powder particles as well as excessive local overheating of the substrate are diminished. Furthermore, because of the small laminar plasma jet, it is possible to achieve high spray efficiency in the case of spraying for dental implants. Also, the low level of noise (25–50 dB) and hardly any dust makes it possible to operate MSE under conditions of normal workrooms. Objective: The aim was to investigate, in a mandibular dog model, the effect of functional load on soft‐tissue adaptation as well as crestal bone‐level changes around titanium implants provided with newly developed microplasma‐sprayed CaP coatings. Material and methods: For histomorphometrical evaluation, 56 screw‐type titanium implants were inserted into the mandibles of seven adult Beagle dogs. The implants were either acid etched without an additional coating, coated with a conventionally plasma‐sprayed CaP ceramic (PS), coated with a microplasma‐sprayed CaP ceramic (MPS) or with a microplasma‐sprayed coating at only the apical part (aMPS). To assess the effect of occlusal loading, a split‐mouth design was used. Six weeks after implantation, the implants in one half of the mandible of each dog were functionally loaded whereas the contra lateral implants served as control. One year after loading, the animals were sacrificed. Soft‐tissue dimension as well as marginal bone level were histologically assessed. Results: Histometric analysis of undecalcified histologic sections included the evaluation of the sulcus depth, the dimension of the junctional epithelium and the connective tissue as well as the first bone‐to‐implant contact. For MPS‐surfaced implants, functional loading was associated with – compared with the non‐loaded state – unchanged soft‐tissue dimension. Furthermore, the soft‐tissue dimension did not differ from the dimensions around non‐coated, PS and aMPS implants. Moreover, the first bone‐to‐implant contact was not significantly altered by functional loading and comparable non‐coated, PS and aMPS implants. Conclusion: Within the limits of the experiment, we conclude that, in comparison, functional loading does not affect the marginal soft‐tissue response to MPS CaP‐coated implants. However, in comparison, functional loading might affect marginal bone response to MPS CaP‐coated implants. To cite this article:
Junker R, Manders PJD, Wolke J, Borisov Y, Braceras I, Jansen JA. Bone reaction adjacent to microplasma‐sprayed calcium phosphate‐coated oral implants subjected to occlusal load, an experimental study in the dog. Clin. Oral Impl. Res. 22 , 2011; 135–142.
doi: 10.1111/j.1600‐0501.2010.02025.x     

可吸收性Bio-Gide膜治疗下颌角区局部骨缺损实验研究

目的 :本研究旨在探讨Bio-Gide膜治疗局部骨缺损的效果 ,评估其应用价值。方法 :在8只成年健康雄性新西兰大白兔的双侧下颌角区置备5×5mm2 大小的洞穿性骨缺损 ,一侧为实验侧 ,另一侧为对照侧 ,随机分成2组 (4周 ,8周组 ) ,进行肉眼、x线与组织学观察。结果 :肉眼及x线检查结果显示 :两组动物的对照侧骨缺损均明显存在 ,有的骨缺损内有肌肉长入 ,骨缺损面积增大 ;两组动物的实验侧骨缺损有不同程度修复 ,并测得实验侧骨缺损中央2×2mm2区域的平均骨密度高于对照侧 ,两者在统计学上有显著差异。组织学检查实验侧骨缺损骨性修复。结论 :Bio-Gide膜能有效阻挡软组织长入骨缺损区 ,作为骨细胞载体促进骨修复。     

Induced osteogenesis using biodegradable and titanium periosteal distractors

BackgroundNew bone formation can result from periosteal distraction. This is achieved through progressive uplifting of the periosteum by increasing the interface between it and the bone surface.ObjectiveThis study investigated the impact of gradual periosteal distraction using biodegradable materials and titanium distraction devices.Materials and methods20 rabbits were separated into 2 groups. Distraction devices were placed in all groups after reflecting the calvarial periosteum. The device was actuated following 7 days. Group 1 got titanium device and Hydroxyapatite HA with poly-l-lactide (PLLA) device was utilized in group 2. Five animals were sacrificed from each group following 4 and 6 weeks. Newly formed bone was histologically and radiographically assessed.ResultsThe histological observations showed that both distraction devices successfully induced osteogenesis and effectively distracted the soft tissue following 4 and six weeks. The study showed scattered bone trabeculae, with adipose tissue and multiple dome-shaped bones. Micro-computed tomography showed newly formed bone that was far less radiopaque than the initial basal bone. The connective tissue appeared as a radiolucent area that decreased gradually toward the fixation point of the device. At 6 weeks, the percentage of new bone was significantly higher than at 4 weeks for both devices. The PLLA device showed more bone than did the titanium device at both 4 and 6 weeks, but no significant difference was observed.ConclusionsBoth distraction devices were effective in distracting the periosteum and inducing new vascularized bone. The PLLA device induced more bone than the titanium device. Thus, the distractor composition may influence the new bone.     

Periosteal distraction osteogenesis and barrier membrane application: an experimental study in the rat calvaria

Background: Distraction of the periosteum results in the formation of new bone in the gap between the periosteum and the original bone. We postulate that the use of a barrier membrane would be beneficial for new bone formation in periosteal distraction. Methods: To selectively influence the contribution of the periosteum, a distraction plate with perforations was used alone or covered by a collagen barrier membrane. All animals were subjected to a 7‐day latency period and a 10‐day distraction period with a rate of 0.1 mm/day. Four animals per group with or without a barrier membrane were sacrificed at 2, 4, and 6 weeks after the end of the distraction. The height of new bone generated relative to the areas bound by the parent bone and the periosteum was determined by histomorphometric methods. Results: New bone was found in all groups. At the periphery of the distraction plate, significant differences in bone height were found between the hinge and the distraction screw for the group without barrier membrane at 2 weeks (0.39 ± 0.19 mm) compared to 4 weeks (0.84 ± 0.44 mm; P = 0.002) and 6 weeks (1.06 ± 0.39 mm; P = 0.004). Differences in maximum bone height with and without a barrier membrane were observed laterally to the distraction plate at 2 weeks (1.22 ± 0.64 versus 0.55 ± 0.14 mm; P = 0.019) and 6 weeks (1.61 ± 0.56 versus 0.73 ± 0.33 mm; P = 0.003) of the consolidation period. Conclusion: Within the limitations of the present study, the application of a barrier membrane may be considered beneficial for new bone formation induced by periosteal distraction.     

Early and immediate loading of titanium implants with fluoride-modified surfaces: results of 5-year prospective study

Objective: Multiple experimental and animal studies have shown that topographic, mechanical and chemical properties of implant surfaces lead to in vivo responses such as increased bone formation, increased bone anchorage and reduced healing time. A fluoride modification of the titanium implant surface also seems to positively influence bone anchorage as compared with unmodified titanium implants. Using implant survival and marginal bone loss as primary outcome parameters, the purpose of the present prospective study was to investigate whether a fluoride modification of the titanium implant surface has positive clinical effects. Materials and methods: The 17 patients included in this study received 49 Astra Tech OsseoSpeed^? implants for various indications in the maxilla and mandible. Implants were either loaded immediately or after a mean healing period of 9.56 weeks. Fifteen patients were followed up clinically including radiographic examination for 5 years. Forty‐two implants were assessed for implant survival, marginal bone loss, surgical and/or prosthetic complications, presence or absence of plaque, signs of inflammation and size of the papilla. Results: Of the original 17 patients, 15 patients were available for the full 60‐month follow‐up. One early implant failure occurred, leading to an implant survival rate of 97%. Radiographic analyses demonstrated stable bone conditions with a mean marginal bone loss of 0.1 mm (SD 0.4 mm, min ?0.7 mm, max 1.7 mm) after 5 years of function. Immediately loaded implants did not show a different mean marginal bone loss as compared with implants that were not loaded immediately. Repeated soft‐tissue examinations revealed healthy conditions in terms of 6.1% plaque and 4.2% of the implants with signs of inflammation at the 5‐year control. Discussion: Implants used in this study had high survival and success rates after 5 years. Marginal bone was well maintained, irrespective of the loading regime. To cite this article:
Mertens C, Steveling HG. Early and immediate loading of titanium implants with fluoride‐modified surfaces: results of 5‐year prospective study.
Clin. Oral Impl. Res. xx , 2011; 000–000.     

The effect of permanent grafting materials on the preservation of the buccal bone plate after tooth extraction: an experimental study in the dog

Objectives: The aim of the present study was to evaluate the effects of a novel bone substitute system (Natix^®), consisting of porous titanium granules (PTG) and a bovine‐derived xenograft (Bio‐Oss^®), on hard tissue remodelling following their placement into fresh extraction sockets in dogs. Material and methods: Six modalities were tested; Natix^® granules with and without a covering double‐layered Bio Gide^® membrane; Bio‐Oss^® with and without a covering double‐layered Bio Gide^® membrane; and a socket left empty with and without a covering double‐layered Bio Gide^® membrane. Linear measurements, indicative of buccal bone height loss, and an area measurement indicative of buccal bulk bone loss were made. The statistical analysis was based on the Latin Square design with two blocking factors (dog and site). Tukey's post hoc test was used to adjust for multiple comparisons. Results: Histological observation revealed that while bone formed around both the xenograft and the titanium particles, bone was also noted within titanium granules. Of the five modalities of ridge preservation techniques used in this study, no one technique proved to be superior. Conclusion: The titanium granules were observed to have promising osseoconductive properties. To cite this article:
Bashara H, Wohlfahrt JC, Polyzois I, Lyngstadaas SP, Renvert S, Claffey N. The effect of permanent grafting materials on the preservation of the buccal bone plate after tooth extraction: an experimental study in the dog.
Clin. Oral Impl. Res. 23 , 2012; 911–917
doi: 10.1111/j.1600‐0501.2011.02240.x     

Guided bone regeneration around dental implants in the atrophic alveolar ridge using a bioresorbable barrier. An experimental study in the monkey.

The aim of this study was to evaluate guided bone regeneration (GBR) around dental implants placed in atrophic alveolar ridges using an experimental, nonporous bioresorbable barrier. In 8 Rhesus monkeys, the maxillary canines and lateral incisors were extracted bilaterally and the remaining alveoli were reduced to create atrophic ridges. After a healing period of 3 months, soft tissue expansion was performed using a subperiosteal tissue expander. After 1 month of tissue expansion, an IMZ implant was placed in the atrophic ridge on each side in such a way that its coronal 4 mm to 5 mm remained circumferentially exposed above the bone level. The test implants were covered with a bioresorbable barrier made of poly (D,L‐lactid‐co‐tri‐methylencarbonate) in a 70/30 ratio, whereas the control implants were covered with a nonresorbable expanded polytetrafluoroethylene (e‐PTFE) barrier. The e‐FTFE barriers were stabilized with titanium minipins while the bioresorbable barriers were analogously fixed using bioresorbable minipins made of poly (L‐lactid‐co‐D,L‐lactid) 70/30. Clinical healing progressed uneventfully in both groups and no soft tissue dehiscences occurred. Histometric and histomorphometric analyses were performed 5 months post surgery. Both test and control implants exhibited direct bone‐to‐implant contact to variable extents. The mean direct mineralized bone‐to‐implant contact length fraction was 32% of the total implant length in the test sites and 58% in the control sites. Control sites exhibited significantly greater bone fill compared to the experimental sites ( P <0.00l). Histologic observations of test specimens demonstrated a moderate inflammatory reaction related to the degradation and resorption products of the barrier. In conclusion, the nonresorbable e FTFE GBR barrier was found to be superior to the bioresorbable barriers tested in the present investigation.     

In situ soft tissue regeneration using periosteal distraction: A preliminary study in the rat calvarial model

AimIn this study, we aimed to evaluate soft tissue generated by periosteal distraction.BackgroundManagement of soft tissue defects represents a challenge in dentistry. Previous periosteal distraction studies documented partial fill of the distraction space with newly-generated bone and fibrous connective tissue.Material and methodsTitanium meshes were inserted in subperiosteal tunnels in the calvaria of 20 rats through coronal incision. The devices were immediately activated after insertion by elevation of one side at 1 mm/day for 3 days. Rats were then divided into two groups (n = 10). Animals were sacrificed after 2 weeks (Group 1) and after 4 weeks (Group 2). Distraction sites specimens were embedded in paraffin and analyzed histologically and histomorphometrically.ResultsIn both groups, new periosteum was regenerated and covered the original bone surface in the distraction site. Distraction spaces showed a predomination of hyper-vascularized connective tissue and little new bone formation near to the stable end of the device. The 4-week findings showed more organized collagen fibers with less vascularity compared to the 2-week findings.ConclusionThe periosteal distraction technique can effectively regenerate connective tissue. It may open a new modality in the guided tissue regeneration for soft tissue augmentation.     

Influence of a microgrooved collar design on soft and hard tissue healing of immediate implantation in fresh extraction sites in dogs

Objective: This study compared the alveolar bone reduction after immediate implantation using microgrooved and smooth collar implants in fresh extracted sockets. Material and methods: Four mongrel dogs were used in this study. The full buccal and lingual mucoperiosteal flaps were elevated and the third and fourth premolars of the mandible were removed. The implants were installed in the fresh extracted sockets. The animals were sacrificed after a 3‐month healing period. The mandibles were dissected and each implant site was removed and processed for a histological examination. Results: During healing, the marginal gaps in both groups, which were present between the implant and the socket walls at implantation, disappeared as a result of bone filling and resorption of the bone crest. The buccal bone crests were located apical of its lingual counterparts. At the 12‐week interval, the mean bone–implant contact in the microgrooved group was significantly higher than that of the turned surface group. From the observations in some of the microgrooved groups, we have found bone attachment to the 12 μm microgrooved surface and collagen fibers perpendicular to the long axis of the implants over the 8 μm microgrooved surface. Conclusion: Within the limitations of this study, microgrooved implants may provide more favorable conditions for the attachment of hard and soft tissues and reduce the level of marginal bone resorption and soft tissue recession. To cite this article:
Shin S‐Y., Han D‐H. Influence of microgrooved collar design on soft and hard tissue healing of immediate implantation in fresh extraction sites in dogs.
Clin. Oral Impl. Res. 21 , 2010; 804–814.
doi: 10.1111/j.1600‐0501.2010.01917.x     

小型猪骨膜成骨修复下颌骨节段性缺损的研究

目的:探讨原位骨膜成骨修复小型猪下颌骨节段性缺损的可行性。方法:选用13个月龄小型猪8只,雌雄不限,拔除右侧下颌前后磨牙3个月后,随机分为保留骨膜组(A组)和不保留骨膜组(B组),每组4只。再按骨缺损长度分为30 mm组和40 mm组,每组各2只。制备小型猪下颌骨体部30 mm和40 mm节段性骨缺损,利用钛板固定两侧骨断端,A组完整保留缺损区颊舌侧的骨膜并将其严密缝合形成一封套层,B组则不保留骨膜,术后4、8、12周进行影像学观察。结果:影像学观察保留骨膜组术后12周完成骨连接,新生骨形态规则,不保留骨膜组未完成骨连接,仅在骨断端有极少量新生骨,且形态不规则。结论:利用骨膜原位成骨可以修复下颌骨较大范围节段性骨缺损。     

Submerged and transmucosal healing yield the same clinical outcomes with two-piece implants in the anterior maxilla and mandible: interim 1-year results of a randomized, controlled clinical trial

Objectives: To test whether or not transmucosal healing at two‐piece implants is as successful as submerged placement regarding crestal bone levels and patient satisfaction. Material and methods: Adults requiring implants in the anterior maxilla or mandible in regions 21–25, 11–15, 31–35 or 41–45 (WHO) were recruited for this randomized, controlled multi‐center clinical trial of a 5‐year duration. Randomization was performed at implantation allowing for either submerged or transmucosal healing. Final reconstructions were seated 6 months after implantation. Radiographic interproximal crestal bone levels and peri‐implant soft tissue parameters were measured at implant placement (IP) (baseline), 6 and 12 months. Patient satisfaction was assessed by a questionnaire. A two‐sided t‐test (80% power, significance level α=0.05) was performed on bone‐level changes at 6 and 12 months. Results: One hundred and twenty‐seven subjects were included in the 12‐month analysis (submerged [S]: 52.5%, transmucosal [TM]: 47.2%). From IP to 6 months, the change in the crestal bone level was ?0.32 mm (P<0.001) for the S group and ?0.29 mm (P<0.001) for the TM group. From IP to 12 months, bone‐level changes were statistically significant in both groups (S ?0.47 mm, P<0.001; TM ?0.48 mm, P<0.001). The mean differences of change in the bone levels between the two groups were not statistically significant at either time point, indicating the equivalence of both procedures. For both groups, very good results were obtained for soft tissue parameters and for patient satisfaction. Conclusions: Transmucosal healing of two‐piece implants is as successful as the submerged healing mode with respect to tissue integration and patient satisfaction within the first 12 months after IP. To cite this article:
Hämmerle CHF, Jung RE, Sanz M, Chen S, Martin WC, Jackowski J, Ivanoff CJ, Cordaro L, Ganeles J, Weingart D, Wiltfang J, Gahlert M. Submerged and transmucosal healing yield the same clinical outcomes with two‐piece implants in the anterior maxilla and mandible: interim 1‐year results of a randomized, controlled clinical trial.
Clin. Oral Impl. Res 23 , 2012; 211–219.
doi: 10.1111/j.1600‐0501.2011.02210.x     

Maxillary sinus augmentation with autologous bone harvested from the lateral maxillary wall combined with bovine‐derived hydroxyapatite: clinical and histologic observations

Objective: The aim of this study was to determine the clinical efficacy of a mixture of autologous bone harvested from the lateral wall of the maxilla using bone shavers and bovine‐derived hydroxyapatite (HA) placed as a graft to elevate the maxillary sinus floor. The histological picture of tissue found in the sinus, the survival rate and the success of the implants were all evaluated. Material and methods: A total of 90 titanium implants were placed in 34 patients. In all of them, the lateral maxillary wall was harvested as a particulate bone graft, subsequently mixed with bovine‐derived HA and packed in the sinus cavity. The lateral access window was then covered with a bioresorbable porcine‐derived collagen membrane. In 32 sinuses, a two‐stage surgery was performed, while in the remaining 10 cases a one‐stage surgery was carried out. In the two‐stage approach, 14 randomly selected biopsies were obtained at the time of implant insertion after a healing period of 9 months. The histological specimens were histologically and histomorphometrically evaluated. Results: One implant was lost, leading to a survival rate of 98.9%. The new bone consisted of lamellae of living bone contained osteocytes and in close contact with bovine bone particles that were partly infiltrated by newly formed bone. Bovine bone particle resorption could not be found. The histomorphometric analysis showed the following averages: 29% of newly formed bone and 21% of anorganic bovine bone. The marrow spaces made up the remaining 50% of the specimens. Conclusion: Sinus lift graft with autologous bone harvested from the maxillary lateral wall combined with demineralized bovine bone leads to a predictable outcome regarding the amount of bone formation in sinus floor augmentation. To cite this article:
de Vicente JC, Hernández‐Vallejo G, Braña‐Abascal P, Peña I. Maxillary sinus augmentation with autologous bone harvested from the lateral maxillary wall combined with bovine‐derived hydroxyapatite: clinical and histologic observations.
Clin. Oral Impl. Res. 21 , 2010; 430–438
doi: 10.1111/j.1600‐0501.2009.01877.x     

Augmentation of the rat mandible using guided tissue regeneration

The aim of the present study was to investigate whether it is possible to increase the height of the rat mandible at its inferior border using a bioresorbable membrane adapted to create a secluded space for ingrowth of bone tissue. The experiment was carried out in 18 rats. The mandibular ramus was exposed at both sides. A standardized titanium microimplant was then inserted in the naturally existing curvature at the inferior border of the mandible, serving as a fixed reference and space maker. The mandibular border on one side was covered with a polyhydroxybutyrate bioresorbable membrane, and the contralateral side, serving as control, received no membrane before closure of the wound. The membranes were placed in such a way that a space was created in the curvature between the membrane and the inferior border of the mandible. Macerated jaw specimens representing 6 months of healing demonstrated substantial amounts of bone formation in the curvature of the inferior border of the mandible, resulting in a flattening of the inferior border. Negligible amounts of bone formation had occurred in the control sides. Histological analysis demonstrated that. in 4 of 6 experimental specimens, the space created by the membrane was completely filled with new bone after 6 months of healing, but in some specimens soft tissue seemed to have migrated into the space through ruptures of the membrane or because of poor membrane adaptation at its lateral borders, thereby inhibiting bone formation. Only negligible bone formation had occurred at the control sides. It can be concluded that augmentation of the mandible can be accomplished using a bioresorbable membrane of polyhydroxybutyrate adapted to create a secluded space for ingrowth of bone tissue. but the membrane must be modified regarding its physical properties before clinical use in maxillofacial surgery.