Implant survival after graftless sinus floor augmentation in highly atrophic maxillae: a randomized controlled trial in a split mouth study.

PURPOSE: The success rate of dental implants after graftless sinus augmentation versus conventional sinus augmentation surgery in atrophic maxillae in edentulous patients was investigated. METHODS: This randomized study was performed in ten edentulous patients with marked maxillary atrophy. On the graftless side, the sinus membrane was lifted by a resorbable membrane. The control side was augmented with a mixture of autografts and xenografts. Implant placement followed 6 months postoperatively. Outcomes were implant survival, success of prosthetic rehabilitation and stability of vertical bone gain. RESULTS: Ten patients were included. Postoperative radiology showed sufficient bone gain on both maxillary sides. Follow-up varied from 57 to 88 months. The conventional side showed significant (p = 0.041) more bone gain than the experimental side (respectively, 9.69 mm and 6.20 mm). A total of 59 implants were placed: 30 after conventional, 29 after graftless augmentation. One implant was lost on the conventional side and four on the experimental side. The implant survival was significantly higher on the conventional side (96.7% vs. 86.2%, p < 0.001, RR = 4.14). Prosthetic restoration was functionally successful in all cases. CONCLUSION: Bone gain and implant survival were significantly lower in the non-grafted side versus the grafted side. Prosthetic rehabilitation was possible in all ten patients. The non-grafted technique may have some potential for clinical use, although it showed poorer results. Trial registration The Netherlands Trialregister. NTR NL3541 (NTR3696). Registered 20 January 2013, https://www.trialregister.nl/trial/3541 .

Pre-implantological bone formation in the floor of the maxillary sinus in a self-supporting space.

INTRODUCTION: In edentulous patients the form and size of the maxillary sinus vary greatly. Therefore sinus floor augmentation is a standard procedure for implantological purposes. As the sinus membrane cannot be characterized as periosteum, various augmentation materials are used. HYPOTHESIS: an artificially generated space underneath the sinus membrane in the floor of the sinus will lead to spontaneous callus forming and a stable bony consolidation without augmentation material. METHODS: Ten edentulous patients with highly atrophic maxillae were selected. Augmentation of the sinus floor was carried out in a split-mouth study design: On one side a combination of autogenous and xenogenous bone was used, and on the contralateral side a sinus membrane elevation was performed without using any substitutes. After a 6-month interval bone specimens from the test regions were harvested during implant placement. RESULTS: Clear histological evidence of new bone formation was found in all human bone specimens. An active de-novo bone formation process could be proven by the presence of Haversian systems (osteons) displaying osteoblastic and osteoclastic activity. CONCLUSION: In the maxillary sinus of edentulous patients a spontaneous callus-derived de-novo bone formation is possible by elevating the sinus membrane without using augmentation materials.

Elevation of the maxillary sinus membrane for de-novo bone formation: First results of a prospective study in humans.

PURPOSE: Sinus floor elevation via the lateral window approach represents a reliable technique for bone augmentation in the atrophic posterior maxilla. It is known that sinus membrane elevation leads to new bone formation. This prospective clinical study compared a specific technique in sinus membrane elevation with a conventional sinus floor augmentation (xenogenous/autogenous bone) in a human split mouth model. METHODS: Five edentulous patients with highly atrophic posterior maxillae were included in this study. On one maxillary side a degradable PDLLA-membrane was placed to create a space underneath the sinus membrane. Contralateral a mixture of autogenous and xenogenous bone was used for sinus floor augmentation. A two-stage procedure was carried out. The following variables were assessed: bone regeneration on cone-beam computed tomography (cone-beam CT), implant success, prosthetic comfort and patient satisfaction. Bone biopsies were taken with simultaneous implant placement. The samples were histologically analyzed. RESULTS: Cone-beam CTs revealed new bone formation on both sides. Thirty implants were placed, 15 in the augmented region and 15 in the non-augmented side. Thirty bone biopsies were taken and evaluated. Vital new bone was detected on the experimental side (osteoinductivity). On the conventional side a mixture of autogenous and residual bone substitute material was seen (osteoconductivity). Implant survival was 100% so far. Patient's satisfaction was high and prosthetic complications were not encountered. CONCLUSION: As it provides the highest rate of bone formation, autogenous bone in combination with bone substitute material can be considered as a very reliable standard procedure in sinus floor augmentation. The specific sinus membrane elevation technique as presented here showed satisfying results and might be a suitable alternative for maxillary sinus augmentation.

Sinus floor augmentation with recombinant human growth and differentiation factor-5 (rhGDF-5): a pilot study in the Goettingen miniature pig comparing autogenous bone and rhGDF-5.

AIM: The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) in combination with a beta-tricalcium phosphate (beta-TCP) scaffold material results in superior bone formation in sinus floor augmentations in miniature pigs compared with a particulated autogenous bone graft combined with the scaffold material. MATERIAL AND METHODS: Six adult female Goettingen minipigs underwent a maxillary sinus floor augmentation procedure. In a split-mouth design, the sinus floors were augmented with beta-TCP mixed with autogenous cortical bone chips, in a ratio of approximately 1 : 1, on one side. The contralateral test site was augmented using beta-TCP coated with two concentrations of rhGDF-5 (400 microg rhGDF-5/g beta-TCP or 800 microg rhGDF-5/g beta-TCP; three animals in each case). Simultaneously, one dental implant was inserted into each sinus floor augmentation. After 12 weeks, a histological and histomorphometric assessment of non-decalcified histological specimens was made. RESULTS: There were significantly higher mean values of volume density of newly formed bone using beta-TCP coated with two concentrations of rhGDF-5 (400 microg: 32.9%; 800 microg: 23.9%) than with the corresponding control (autogenous bone/beta-TCP) (14.6%, 12.9%) (P=0.012, P=0.049). The bone-to-implant contact rates (BIC) were significantly enhanced in test sites (400 microg: 84.2%; 800 microg: 69.8%) compared with the corresponding control sites (24.8%, 40.8%) (P=.027, P=.045). CONCLUSION: rhGDF-5 delivered on beta-TCP significantly enhanced bone formation compared with beta-TCP combined with autogenous bone in sinus lift procedures in miniature pigs.

Sinus floor augmentation with recombinant human growth and differentiation factor-5 (rhGDF-5): a histological and histomorphometric study in the Goettingen miniature pig.

AIM: The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) enhances bone formation in sinus floor augmentations in miniature pigs. MATERIAL AND METHODS: The maxillary sinus floors in 12 adult female Goettingen minipigs were augmented with beta-tricalcium phosphate (beta-TCP) on one side. The contralateral test side was augmented using two concentrations of rhGDF-5 (400 microg rhGDF-5/g beta-TCP; 800 microg rhGDF-5/g beta-TCP) delivered on beta-TCP (six animals each). One dental implant was inserted into each sinus floor augmentation. After 4 and 12 weeks, histological and histomorphometric assessment of non-decalcified histological specimens was performed. RESULTS: The results showed significantly higher mean values of volume density (VD) of newly formed bone using the concentration of 400 microg/g beta-TCP (22.8%) compared with the respective control (8%) after 4 weeks (P=0.05). The bone-to-implant contact rates were also significantly enhanced after 4 weeks between test sites (400 microg: 41.9%; 800 microg: 40.6%) and control sites (400 microg: 7.8%; 800 microg: 16.4%) (400 microg: P=0.024; 800 microg: P=0.048). CONCLUSION: It is concluded that rhGDF-5 delivered on beta-TCP significantly enhanced early bone formation compared with beta-TCP alone in sinus lift procedures in miniature pigs.

[Reconstruction of the anterior wall of frontal sinus with biopolymers]. / Rekonstruktion der Stirnhöhlenvorderwand mit Biopolymeren.

The two biopolymers Ethisorb and its modification Ethisorb Rapid were implanted in 80 defects of the anterior wall of frontal sinus in 20 Goettingen minipigs to analyze density of trabecula (Mann-Whtiney-Rank-Sum-Test), degradation of biopolymers and histomorphology. To optimate bone regeneration, particular resorbable membranes and autogenic spongiosa chips were used. The animals were killed after six, 12, 26 and 52 weeks and then postoperative undecalcified bone cuts were obtained. All in all, with Ethisorb contrary to Ethisorb Rapid a faster biopolymer resorption in the 12th and 26th week with a statistically significant greater density of trabecula could be observed. The use of resorbable membranes and autogenic spongiosa chips led, in comparison to simple implantation of biopolymers, to significantly greater densities of trabecula. The use of Ethisorb contrary to Ethisorb Rapid with membranes led to a Guided Bone Regeneration (GBR) with persistence of membrane particles to week 12 and 26. By mixing biopolymers with autogenic spongiosa chips a multiloculated bone regeneration could be generated. For Ethisorb with resorbable membranes and autogenic spongiosa chips the best bone regeneration with highest densities of trabecula could be recognized.

[Histological comparison of different biopolymers in osseous defects]. / Histologischer Vergleich unterschiedlicher Biopolymere im enossalen Defekt.

The goal of this animal study in Goettingen minipigs was to compare Ethisorb with its modification Ethisorb Rapid where the hydrolytic degradation process has started, with respect to degradation and bony substitution qualitites. For comparison, both biopolymers were implanted with and without addition of autogenic spongiosa chips in comparison with blank defects in metaphysis of the tibia. The animals were killed after six, 12, 26 and 52 weeks. Undecalcified bone cuts were obtained and subjected to a histomorphometric and histomorphological analysis. All in all, with increasing time after implantation a continuous decrease of the density of trabecula could be observed. In comparison to Ethisorb Rapid and blank defects, the implantation of the slowly degrading but quickly resorbing Ethisorb led to statistically significantly higher densities of trabecula (Tuckey Test, p < or = 0.05) and to best bone regeneration. In contrast to this, Ethisorb Rapid could be degraded more quickly but resorbed more slowly. In the polarizing microscope, Ethisorb could still be detected after 12 weeks of implantation. Ethisorb Rapid could still be detected after 26 weeks of implantation. To conclude, Ethisorb proved to be a suitable scaffold for autogenic spongiosa-chips in critical-size defects of the tibia so that a multiloculated bone regeneration could be obtained.

Volumetry of human molars with flat panel-based volume CT in vitro.

The flat panel-based volume computed tomography (fpVCT) is a new CT device applicable for experimental, three-dimensional evaluation of teeth at a resolution of about 150 microm in the high contrast region. The aim of this study was to investigate whether fpVCT was suitable for quantification of the volumes of dental hard tissues and the root canal system to establish a new method for morphological studies. Fifty-two extracted third molars (maxillary: 31, mandibular: 21) were examined with a prototype of an fpVCT using a volumetry algorithm at different levels according to the radiographic density of enamel and dentine. Volumetry of the root canal system was performed after "region growing segmentation": starting from a voxel in the centre of the root canal, this algorithm searches voxels of same density in the surrounding. The volumetry of the root canal system was stopped by the investigator at the apical constriction. Results showed that dentine, enamel and root canal system could be well distinguished in three-dimensional images. Volumetry yielded the following data (cm(3), mean+/-SD): dentine 0.438+/-0.111, enamel 0.227+/-0.051, root canal system 0.052+/-0.017 and total volume 0.753+/-0.159. In conclusion, the fpVCT is appropriate for non-destructive volumetry of large numbers of teeth in experimental laboratory studies.

Piezoelectric osteotomies in craniofacial procedures: a series of 15 pediatric patients. Technical note.

Frontoorbital advancement has become a standard method both to increase intracranial volume and to improve facial appearance in patients with syndromal or nonsyndromal craniosynostosis. Relevant complications of this procedure include severe hemorrhage and trauma to intracranial, orbital, or facial soft tissues, which mostly arise during the process of bone exposure or osteotomy. To minimize the risk of soft tissue injury and to increase the precision of the osteotomy, the authors applied a piezoelectric osteotome for frontoorbital advancement in 15 patients with craniosynostosis seen consecutively (mean age 11.3 months). They demonstrated that this new device can cut cranial bones using ultrasonic microvibrations created by piezoelectric effects. In all patients, this instrument allowed an easy and precise handling during osteotomy with a reduced amount of trauma to adjacent soft tissues and with no complications. Although the time required for piezoelectric osteotomy was longer compared with conventional techniques, the total operation time remained approximately the same because the preparation requirements are less extensive. Postoperatively, bone regeneration was uneventful. The authors conclude that this new technique of piezoelectric osteotomy is a valuable tool for craniofacial reconstructive surgery in pediatric patients.

Contouring of cranial vault irregularities with hydroxyapatite cement: a clinical and experimental investigation.

The biocompatible hydroxyapatite cement (HAC) is a welcome alternative to the traditional use of autogenous bone for postoperative corrections of cranial vault irregularities. The authors performed experimental studies to show the safety and osseointegration capacity of HAC on animal models and confirm the osseous replacement without toxic reactions. The purpose of the current study was to analyze the clinical outcome after correction of secondary cranial vault irregularities with HAC. Twenty-one patients were treated for residual cranial frontal bone defects after craniotomy with HAC (Bone Source, Stryker Leibinger GmbH, D-79111 Freiburg, Germany). The average age was 38.5 years (range, 23-57 years). All of the patients were male. The average volume per patient was 53.83 g. The volume implanted ranged from 25 to 125 g; in all cases the dura was covered with bone. Irregularities resulted from sunken bone. The authors' clinical series demonstrates that a satisfactory and aesthetically pleasing result can be achieved in one surgical intervention in patients for surgical correction of postoperative cranial vault irregularities using HAC. It permits osseointegration, which makes it relatively resistant to infection. HAC is easy to apply and shape to suit individual needs. HAC is a welcome alternative to the traditional use of autogenous bone for postoperative corrections of cranial vault irregularities.

Cellular, histomorphologic, and clinical characteristics of a new octyl-2-cyanoacrylate skin adhesive.

Short-chained cyanoacrylates have been used for many years for topical skin closure. Toxic effects in cell culture of a new long-chained octyl-2-cyanoacrylate tissue adhesive are compared with those of short-chained ethyl-2- and butyl-2-cyanoacrylates. Two cellular tests were used: the agar overlay test and the MTT test. An in vitro test using copper plates coated with the three types of cyanoacrylates serves for evaluating the stability of polymerized skin adhesives. Bilateral neck skin incisions in Goettingen miniature pigs were glued on one side with Dermabond. On the other side, conventional sutures were applied. After the pigs were killed, the resulting skin samples were tested for the tensile strength of their wound stability. Samples of pig dermis were exemplarily and histomorphologically characterized. A clinical examination after submandibular lymph node dissection should examine the application in humans. Cell culture tests were used to show the toxic effects of the three cyanoacrylates. In a copper test, octyl-2-cyanoacrylate was more stabile than ethyl- and butyl-cyanoacrylates. Breaking strength was 30% lower 28 days after operation with the new product than with sutures. In electron microscopy, octyl-2-cyanoacrylate showed no disadvantages with regard to tissue regeneration and no histotoxicity. For plastic surgery, this new topical skin adhesive is a real alternative with attractive results, as compared with conventional suture.

Classification system and treatment of zygomatic arch fractures in the clinical setting.

A new classification system and algorithm of zygomatic arch fractures is described that provides the surgeon with a useful starting point from which to organize a valid treatment plan and management of zygomatic arch fractures. Hönig Merten (HM) class I is defined as an isolated tripod fracture, HM class II as an isolated stick fracture of the arch, and HM class III is a combined fracture of the malar bone and the zygomatic arch. Although reduction of the class I and II is usually closed, open reduction is mandatory in class III zygomatic arch fractures.

Dove tail osteotomy in distraction osteogenesis of costochondral bone grafts in the mandible: a new concept.

To correct the malocclusion and facial asymmetry in patients with Pruzansky type III hemifacial microsomia after autogenous costochondral grafting during early childhood (two male and three female patients with an average age of 17.8 years), the technique of distraction osteogenesis with a three-dimensional device was used. Because of the missing periosteum of the transplanted rib and its relatively small height compared with the horizontal mandible, a dovetail geometrical pattern osteotomy was introduced to increase the osteotomy surface area, which by itself could enhance the amount of fibrin filaments between 30% and 40% in the hematoma occurring during the initial distraction process. These fibrin filaments are biofunctional guiding structures for the development of the microcallus, followed by enhancement of the bone-healing capacity, which allows optimal bone regeneration. Between 20 and 27 days (mean = 21.5 days) after distraction, complete ossification was noted radiographically in all treated patients. Based on our histological animal studies and clinical investigations, dove tail osteotomy enhances the osteotomized surface area and offers protection to the tension-sensitive structures in the center of the distraction zone. It increases early bone formation and mineralization adjacent to the center zone in the distraction gap. Therefore, the dove tail geometrical pattern in combination with distraction osteogenesis of autologous costochondral grafts in the treatment of congenital Pruzansky type III mandibular hypoplasia is strongly recommended.

Reconstruction of skull bone defects using the hydroxyapatite cement with calvarial split transplants.

PURPOSE: We sought to present a new method for primary reconstruction of traumatic or tumor calvarial defects. PATIENTS AND METHODS: Forty-one patients underwent reconstruction of calvarial bone defects between October 1998 and December 2001. Among them were 19 patients who needed reconstruction of the calvaria due to traumatic bone loss. Five of these trauma cases had insufficient primary reconstruction of the calvaria. Tumor resection caused calvarial defects in 22 patients. For primary reconstruction of the skull bone defects, calvarial split grafts were used to cover the defect as accurately as possible. The monocortical layers of the calvaria were fixed with titanium miniplates. Irregular defects surrounding the transplanted regions were filled with hydroxyapatite cement. In one case of posttraumatic bone loss, hydroxyapatite cement alone was sufficient to reconstruct the defect. RESULTS: The follow-up of each patient was at least 6 months; the longest period was 38 months. Evaluated clinical and radiologic results are stable, showing no measurable side effects. CONCLUSION: Hydroxyapatite cement alone or in combination with calvarial split grafts gave clinically and aesthetically stable results in the reconstruction of skull bone defects. The cement can be used for many reconstruction possibilities in craniofacial surgery.

Tissue engineering of bone for mandibular augmentation in immunocompetent minipigs: preliminary study.

Large mandibular defects caused by trauma, infection or resection of a tumour are still a major problem for plastic and maxillofacial surgeons. The modern concept of tissue engineering combines the osteoinductive effects of osteogenic cells with a suitable scaffold structure to promote differentiation of osteoblasts and optimal matrix production. Critical size mandibular bone defects were therefore made to investigate the osteogenic potential of periosteal cells and a bioabsorbable polymer fleece (Ethisorb 510) in minipigs. Periosteal cells were isolated from four minipigs, expanded in vitro and seeded with fibrin glue into Ethisorb 510 fleeces. Tissue constructs were used to repair critical size mandibular defects and compared with two minipigs with untreated bone defects. Bone healing was evaluated after 90 and 180 days by radiographs and a histological scoring system. The radiographs showed increased radiodensity of defects filled with the cell-fibrin-fleece-constructs compared with the untreated control group after 90 and 180 days in vivo. The defects repaired by the cell-fibrin-scaffolds (180 days in vivo) obtained the highest histological mean score 2.9 (range 2-3), while defects filled by cell-fibrin-scaffolds (90 days in vivo) achieved a mean score of 2.1 (range 2-3). In contrast, the control group (n = 2) scored 1 and 2. The results show that a combination of periosteal cells and polymer fleeces may be a promising approach for clinical mandibular augmentation.

Hydroxyapatite cement (BoneSource) for repair of critical sized calvarian defects--an experimental study.

AIM: In an experimental study the hydroxyapatite cement BoneSource was tested for the ability in relation to the defect size and for its resorption properties. MATERIAL AND METHODS: In an animal study, BoneSource was applied to repair bicortical defects of different sizes in frontal bones of six Goettingen minipigs. The area was evaluated radiographically and histologically 12, 18 and 40 weeks postoperatively. RESULTS: After 40 weeks approximately 90% of the hydroxyapatite cement had been resorbed and replaced with bone. After 12 weeks, approximately 30% had been degraded, and 40% after 18 weeks. In small bone defects, the mucosa of the frontal sinus lined the bone substitute (BoneSource). In the reconstruction of large areas, a membrane was used to stabilize the material. Despite this membranous support, BoneSource material prolapsed into the frontal sinus. DISCUSSION: Hydroxyapatite cement is for the repair of bone defects. It can be moulded to shape the reconstruction. Its use is limited by the defect size and the need for a dry bed. CONCLUSION: BoneSource is well suited to repair small defects with proven high biocompatibility. However, in large defects, the material is not sufficiently stable.

Experimental study of the frontal sinus development on Goettingen miniature pigs.

According to the literature, the development of the frontal sinus cavity is a result of the active immigration of cells from the ethmoidal complex into the os frontale. This migration theory is in contrast to the operative outcome of Apert's syndrome patients, after fronto-orbital advancement. When a fronto-orbital advancement at the age of a few months is performed in these patients while the frontal suture is yet closed, a sinus developed even the distance between nasal root and frontal bone bing up to 2 cm. In order to study the development of the frontal sinus, an animal study on 12 five-week-old infant Goettingen minipigs (GMP) was conducted, which did not have any clinical or histological signs of a frontal sinus development to investigate the development of the frontal sinus in "orthotopically" transplanted frontal bone with an open frontal suture. A comparison was made to a control group. The macro- and microscopical comparison with a control group revealed that the orthotopical transplants in the occipital bone developed epithelium-lined sinus, beginning from the thirty-fifth week. Based on these histomorphological results, a development scheme for the genesis of the sinus frontalis as a model were drawn.

Mandibula distraction osteogenesis for lengthening the mandibula to correct a malocclusion: a more than 70-year-old German concept in craniofacial surgery.

Bone distraction is still on the rise again since McCarthy et al. presented in their clinical investigation new osseous formation in the elongated area while performing the distraction of the mandible in 1992. But at the level of craniofacial skeleton, the initial description to the technique of distraction osteogenesis should be credited to the German craniofacial surgeons Rosenthal for the bone lengthening of the mandible in a microgen patient in 1927. The procedure is described and the original schedules and case are presented.

Facial bone distraction osteogenesis for correction of malocclusion: a more than 70-year-old concept in craniofacial surgery.

Bone distraction has been used increasingly since McCarthy and associates showed in their clinical investigation new osseous formation in the elongated area while performing mandibular distraction in 1992. However, at the craniofacial skeletal level, the initial description of the classic technique of distraction osteogenesis should be credited to German craniofacial surgeons Rosenthal (for bone lengthening of the mandible in a microgenia patient around 1927) and Wassmund (for the clinical advancement of a maxilla in a patient with hypoplasia of the upper jaw in 1926). Both procedures are described, and their original schedules and cases are presented.