Coating with artificial matrices from collagen and sulfated hyaluronan influences the osseointegration of dental implants.

Dental implants are an established therapy for oral rehabilitation. High success rates are achieved in healthy bone, however, these rates decrease in compromised host bone. Coating of dental implants with components of the extracellular matrix is a promising approach to enhance osseointegration in compromised peri-implant bone. Dental titanium implants were coated with an artificial extracellular matrix (aECM) consisting of collagen type I and either one of two regioselectively low sulfated hyaluronan (sHA) derivatives (coll/sHA1Δ6s and coll/sHA1) and compared to commercial pure titanium implants (control). After extraction of the premolar teeth, 36 implants were inserted into the maxilla of 6 miniature pigs (6 implants per maxilla). The healing periods were 4 and 8 weeks, respectively. After animal sacrifice, the samples were evaluated histomorphologically and histomorphometrically. All surface states led to a sufficient implant osseointegration after 4 and 8 weeks. Inflammatory or foreign body reactions could not be observed. After 4 weeks of healing, implants coated with coll/sHA1Δ6s showed the highest bone implant contact (BIC; coll/sHA1Δ6s: 45.4%; coll/sHA1: 42.2%; control: 42.3%). After 8 weeks, a decrease of BIC could be observed for coll/sHA1Δ6s and controls (coll/sHA1Δ6s: 37.3%; control: 31.7 %). For implants coated with coll/sHA1, the bone implant contact increased (coll/sHA1: 50.8%). Statistically significant differences could not be observed. Within the limits of the current study, aECM coatings containing low sHA increase peri-implant bone formation around dental implants in maxillary bone compared to controls in the early healing period.

Comparison of bone-implant contact and bone-implant volume between 2D-histological sections and 3D-SRµCT slices.

Histological imaging is still considered the gold standard for analysing bone formation around metallic implants. Generally, a limited number of histological sections per sample are used for the approximation of mean values of peri-implant bone formation. In this study we compared statistically the results of bone-implant contact (BIC) and bone-implant volume (BIV) obtained by histological sections, with those obtained by X-ray absorption images from synchrotron radiation micro-computed tomography (SRµCT) using osseointegrated screw-shaped implants from a mini-pig study. Comparing the BIC results of 3-4 histological sections per implant sample with the appropriate 3-4 SRµCT slices showed a non-significant difference of 1.9 % (p = 0.703). The contact area assessed by the whole 3D information from the SRµCT measurement in comparison to the histomorphometric results showed a non-significant difference in BIC of 4.9 % (p = 0.171). The amount of the bone-implant volume in the histological sections and the appropriate SRµCT slices showed a non-significant difference by only 1.4 % (p = 0.736) and also remains non-significant with 2.6 % (p = 0.323) using the volumetric SRµCT information. We conclude that for a clinical evaluation of implant osseointegration with histological imaging at least 3-4 sections per sample are sufficient to represent the BIC or BIV for a sample. Due to the fact that in this study we have found a significant intra-sample variation in BIC of up to ± 35 % the selection of only one or two histological sections per sample may strongly influence the determined BIC.

Planning implant positions for an auricular prosthesis with digital data.

The esthetic result of an auricular prosthesis is influenced by the position of the prosthesis incorporating the implants. The entire surface of the patient's head is captured by means of a conventional computed tomography (CT). The digital data are used to mirror the contralateral unimpaired ear for restoration of the impaired side. The virtual ear is integrated into a template covering the auricular defect and indexed to the nasal area with computer-aided technology (CAD/CAM). This virtual template is converted into an acrylic resin template. With that the surgeon and the anaplastologist should determine the optimal implant position of the auricular prosthesis.

Surface-conditioned dental implants: an animal study on bone formation.

AIM: The aim of this study was to determine whether bone formation around surface-conditioned implants is enhanced compared with non-surface-conditioned sandblasted acid-etched titanium implants. MATERIALS AND METHODS: One hundred and forty-four implants were placed in the mandible of 18 minipigs. Before placement, implants were either surface conditioned in a solution containing hydroxide ions (conSF) or assigned to controls. Animals were euthanized after 2, 4 and 8 weeks of submerged healing, the 8-week group receiving polyfluorochrome labelling at week 2, 4, 6 and 8. One jaw quadrant per animal was selected for histological and histomorphometrical evaluation of mineralized bone-implant contact (mBIC), osteoid-implant contact (OIC) and bone volume (BV) analysis. RESULTS: Polyfluorochrome labelling showed no general differences in bone dynamics. mBIC showed the most pronounced differences after 2 weeks, reaching 65.5% for conSF compared with 48.1% for controls, p=0.270. Differences levelled out after 4 weeks (67.4% control, 65.7% conSF) and 8 weeks (64.0% control, 70.2% conSF). OIC levels were initially comparable, showing a slower decline for conSF after 4 weeks. BV was higher for conSF at all times. No significant differences could be found. CONCLUSION: A tendency towards increased mBIC was shown for surface-conditioned implants after short-term healing.

Increased bone formation around coated implants.

AIM: We hypothesized that coating threaded, sandblasted acid-etched titanium implants with collagen and chondroitin sulphate (CS) increases bone formation and implant stability, compared with uncoated controls. MATERIALS AND METHODS: Three different implant surface conditions were applied: (1) sandblasted acid-etched (control), (2) collagen/chondroitin sulphate (low-dose--CS1), (3) collagen/chondroitin sulphate (high-dose--CS2). Sixty 9.5 mm experimental implants were placed in the mandible of 20 minipigs. Bone-implant contact (BIC) and relative peri-implant bone-volume density (rBVD--relation to bone-volume density of the host bone) were assessed after 1 and 2 months of submerged healing. Implant stability was measured by resonance frequency analysis (RFA). RESULTS: After 1 month, coated implants had significantly more BIC compared with controls (CS1: 68%, p<0.0001, CS2: 63%, p=0.009, control: 52%). The rBVD was lower for all surface conditions, compared with the hostbone. After 2 months, BIC increased for all surfaces. No significant differences were measured (CS1: 71%, p=0.016, CS2: 68%, p=0.67, control: 63%). The rBVD was increased for coated implants. RFA values were 71-77 at implantation, 67-73 after 1 month and 74-75 after 2 months. Differences in rBVD and RFA were not statistically significant. CONCLUSIONS: Data analysis suggests that collagen/CS has a positive influence on bone formation after 1 month of endosseous healing.

Mandibular traction--an alternative treatment in infants with Pierre Robin sequence.

PURPOSE: In the Pierre Robin sequence, retrognathia and glossoptosis lead to airway obstruction in infants with or without cleft palate. Mandibular distraction has gained acceptance for the treatment of airway obstruction. However, surgical interventions can result in complications. In our institution, mandibular traction is the standard treatment in cases of severe respiratory distress. PATIENTS AND METHODS: A retrospective study was performed of all infants treated for Pierre Robin sequence at our institution from 1979 to 2007. The diagnosis and type of treatment (positioning/palatal plate or mandibular traction) were evaluated. The palatal plate had several knobs at the anterior alveolar ridge to direct the tongue forward. Mandibular traction was applied using weights transmitted onto the mandible by a custom-made plate fixed at the mandible with circumferential wiring. RESULTS: Nineteen children required airway treatment because of repeated cyanotic episodes and respiratory adaptation disorders. Of these 19 children, 8 had been diagnosed with pure Pierre Robin sequence and 11 also had other congenital abnormalities. Of the 19 patients, 10 (56%) were treated nonoperatively by lateral or prone positioning and/or wearing a palatal plate to stimulate the tongue. In 8 patients, conservative management was not sufficient, and continuous mandibular traction was performed for 2 to 5 weeks using weights of 50 to 200 g. One patient required a tracheostomy because of tracheomalacia. CONCLUSIONS: Surgical therapy using mandibular traction is a minimally invasive alternative to more invasive procedures because no serious complications such as scars or damage to the nerves were encountered.

Postgraduate training in Oral- and Maxillofacial Surgery: Results of a survey among 74 German interns.

The aim of this study was to asses a survey of residents to obtain relevant information about their current situation in training in Oral and Maxillofacial Surgery in Germany. Special focus was given to the personal and clinical preferences of the residents, their main subjects of interest and plans after residency. Furthermore, the different principles of education at German teaching hospitals were evaluated. Overall, 74 questionnaires were completed on a voluntary and anonymous basis by German residents for Oral and Maxillofacial Surgery. Participants' mean age was 32.74 years (68% male, 27% female). Most participants were in the fifth year of training (32%) and members of the German Association of Oral and Maxillofacial Surgery (70%). This rate increased with progress in residency (p = 0.006). Most residents (70%) were employed at university hospitals, followed by non-university hospitals (26%) and private practices (4%). Residents from university hospitals (3.06 ± 0.39 years) were less advanced in training compared to residents from non-university hospitals and private practices (4.10 ± 0.54 years; p = 0.005). Part-time employed residents were significantly younger (30.64 ± 2.37 years) than full-time employed residents (33.25 ± 0.64 years, p = 0.002). Structured concepts of training existed in 64% of the hospitals, while training depending on the current year of residency (42%) was most common. Most of the residents would prefer a systematic rotation system (59%). Main subjects of clinical interest were aesthetic (50%) and orthognathic surgery (46%). The interest in dento-alveolar surgery (34%) significantly increased with participants' age (p = 0.008). Clefts and malformations were favoured by few residents (16%). Most participants planned to specialize in facial plastic surgery after residency (76%). The data collected might give evidence for an increasing importance of structured training concepts in Oral and Maxillofacial Surgery. It might be relevant to enhance the interest and the excitement of residents for oncology, traumatology, cleft and malformation surgery.

Open reduction and internal fixation versus closed treatment and mandibulomaxillary fixation of fractures of the mandibular condylar process: a randomized, prospective, multicenter study with special evaluation of fracture level.

PURPOSE: This randomized, clinical multicenter trial investigated the treatment outcomes of displaced condylar fractures, and whether radiographic fracture level was a prognostic factor in therapeutic decision-making between open reduction and internal fixation (ORIF) versus closed reduction and mandibulomaxillary fixation (CRMMF). PATIENTS AND METHODS: Sixty-six patients with 79 displaced fractures (deviation of 10 degrees to 45 degrees, or shortening of the ascending ramus >or=2 mm) of the condylar process of the mandible at 7 clinical centers were enrolled. Patients were randomly allocated to CRMMF (n = 30 patients) or ORIF (n = 36 patients) treatment. The following parameters were measured 6 months after the trauma. Clinical parameters included mouth opening, protrusion, and laterotrusion. Radiographic parameters included level of the fracture, deviation of the fragment, and shortening of the ascending ramus. Subjective parameters included pain (according to a visual analogue scale), discomfort, and subjective functional impairment with a mandibular functional impairment questionnaire. RESULTS: The difference in average mouth opening was 12 mm (P or=2 mm, should be treated with ORIF, irrespective of level of the fracture.

[Computation and experimental examination of an implant structure made by a fibre-reinforced building method for the bypass of continuity defects of the mandible]. / Berechnung und experimentelle Prüfung einer Implantatstruktur in Faserverbundbauweise für die Uberbrückung von Kontinuitätsdefekten des Unterkiefers.

A partial resection of the lower jaw often has to be carried out in the context of the surgical removal of tumours in the lower jaw, mouth and tongue-floor space and lower jaw fractures with loss of substance, benign bone lesions and extensive difficult inflammation of bone tissue, respectively. The primary reconstruction of the lower jaw after partial resection with loss of continuity is mainly important for functional and aesthetic reasons. The defects of lower jaw continuity are often bridged with metal plates to reconstruct the masticatory function of the lower jaw, temporarily or permanently. Functional as well as aesthetic disadvantages arise in the case of the application of such plates as a result of a high stiffness jump between reconstruction plate and bone and their insufficiently individual design. The employment of biocompatible, carbon-fibre-reinforced Polyetheretherketon (CF-PEEK) permits the development of a geometry- and stiffness-adapted carrying structure for the mandible. For the demand-adapted dimensioning and the test of a CF-PEEK bandage, the application of optical methods, such as the grey value correlation method, is suited as well as numeric methods, such as the finite element method. In an initial analysis of deformation behaviour, the various osteosynthesis configurations are comparatively investigated on a model jaw. The calculations and tests of the lower jaw model show that the use of the new CF-PEEK bandage compared to the use of conventional titanium osteosynthesis plates shows a mechanical behaviour which is much better adapted to the natural lower jaw.

O-phospho-L-serine: a modulator of bone healing in calcium-phosphate cements.

Bone substitution materials are seen as an alternative to autogenous bone transplants in the reconstruction of human bone structures. The aim of the present animal study was to evaluate the clinical handling and the conditions of bone healing after the application of a phosphoserine and collagen-I-modified calcium-phosphate cement (Biozement D). The application of phosphoserine is supposed to influence the texture of the extracellular matrix. Standardised bone defects were created in the lower jaw of 10 adult minipigs. These defects were reconstructed with a pasty calcium-phosphate cement mixture. After a healing time of 4 months, the animals were sacrificed. The mandibles of all animals were resected and non-decalcified histological sections of the areas of interest were prepared. The experiment was evaluated by means of qualitative histology and histomorphometry. The hydroxyapatite cement entirely hardened intraoperatively. Modelling and handling of the cement was facile and the margin fit to the host bone was excellent. Histology showed that resorption started in the periphery and proceeded exceptionally fast. The bony substitution, especially in phosphoserine-endowed cements, was very promising. After a healing period of 4 months, phosphoserine cements showed a bone regeneration of nearly two-thirds of the defect sizes. In the applied animal experiment, the newly developed hydroxyapatite collagen-I cement is well suited for bone substitution due to its easy handling, its excellent integration and good resorption characteristics. The addition of phosphoserine is very promising in terms of influencing resorption features and bone regeneration.

Fractures of the mandibular condyle: A comparison of patients, fractures and treatment characteristics between Groningen (The Netherlands) and Dresden (Germany).

PURPOSE: To explore differences in patient, fracture, accident and treatment characteristics between patients treated for a mandibular condyle fracture in the University Centres of Dresden and Groningen, as an explanation for differences treatment results. MATERIALS AND METHODS: Patients' fracture, accident and treatment characteristics were obtained from the medical records of Dresden and Groningen from January 1, 2008, to August 31, 2011, and were analysed using logistic regression analysis. RESULTS: In Dresden, compared to Groningen, patients were generally older (OR 1.03, 95% CI 1.02; 1.05, per year), were more often male (OR 2.54, 95% CI 1.48; 4.34) and more often had intracapsular (OR 2.95, 95% CI 1.67; 5.22) and low condylar (OR 1.86, 95% CI 1.14; 3.04) fractures. In Groningen 98% of patients received closed treatment and in Dresden 42%. CONCLUSION: Significant differences in patients and fractures and treatments were found between both Centres. These differences can partly be explained by the demographics of the cities and differences in imaging techniques (e.g., computed tomography, Orthopantomogram, Towne projection) applied to identify fractures. This study illustrates that differences in diagnosis, treatment and outcome are not only related to the health care system but also to differences in patient characteristics between centres.

Analysis of the base excision repair genes MTH1, OGG1 and MUTYH in patients with squamous oral carcinomas.

A number of environmental factors, such as tobacco and alcohol, have been implicated, through oxidative DNA damage, in the development of squamous cell carcinomas of the head and neck (SCCHN). Several pathways are involved in the repair of DNA lesions caused by oxidative stress, such as the base excision repair system (BER), which repairs mutation involving 8-oxoguanine and comprises the MUTYH, OGG1 and MTH1 genes. We analysed 29 patients, assessing germline polymorphisms or mutations in these genes by complete genomic sequencing of exons and adjacent intronic regions. Thirty healthy blood donors served as controls. No pathogenic germline mutations were identified. We found common and rare new variants in the coding and adjacent intronic regions. In summary, our data do not support a major role for MUTYH, OGG1 and MTH1 variants in the etiology of sporadic squamous oral/oropharyngeal carcinomas. This does not exclude the involvement of the three BER genes in the tumorigenesis of SCCHN through other mechanisms such as promotor hypermethylation, genomic rearrangements or mutations involving regulatory sequences.

Influence of extracellular matrix coatings on implant stability and osseointegration: an animal study.

Aim of the present study was to test the hypothesis that the application of components of the extracellular matrix such as glycosaminoglycans used as implant surface coatings in combination with collagen, with and without growth factor, can lead to enhanced ossification and thus improve implant stability compared with collagen coatings alone. Twenty miniature pigs received 120 experimental titanium implants in the mandible. Three types of surface coatings were created: (1) collagen type I (coll), (2) collagen type I/chondroitin sulphate (coll/CS), (3) collagen type I/chondroitin sulphate/BMP-4 (coll/CS/BMP). Periimplant bone formation was assessed within a defined recess along the length axis of the implant. Bone-implant contact (BIC) and bone volume density (BVD) were determined, using both histomorphometry and synchrotron radiation micro computed tomography (SRmicroCT). To measure implant stability, resonance frequency analysis was applied after implantation and 1, 3, 7, and 22 weeks after placement. BIC was highest for coll/CS coated implants, followed by coll, p = 0.082. Histomorphometric BVD did not significantly change for any coating. SRmicroCT analysis showed an increased BVD for collagen coated implants, compared with the other two surface coatings. Implant stability showed a decrease for all coatings up to the third week. At 22 weeks, all coatings showed an increase in stability without reaching their initial level. Highest stability was reached for coll coated implants, p = 0.051. It was concluded that collagen and coll/CS implant coatings have advantageous characteristics for peri-implant bone formation, compared with the further integration of BMP-4.

Surgical treatment of fractures of the mandibular condyle: a comparison of long-term results following different approaches - functional, axiographical, and radiological findings.

AIM: While functionally stable osteosynthesis is a generally accepted method to treat all dislocated fractures of the skull, open reduction and rigid fixation of fractures of the mandibular condyle are still controversial. The risks involved in the surgical approaches and the difficulties during reposition are the main controversies. Improvements made in surgical access and osteosynthesis materials as well as the development of special instruments were the reasons for re-evaluating the surgical results. METHODS: Forty patients with displaced or dislocated fractures of the mandibular condyle were re-examined. In 20 patients (21 fractures) an intraoral approach, in 20 more patients (24 fractures) an extraoral perimandibular approach was applied. The results were compared by means of axiography and radiology as well as clinically with regard to function 6 months postoperatively. RESULTS: While almost all fractures were correctly reduced following application of an extraoral access, reduction was correct in only 50% of the patients treated with an intraoral approach. Re-displacement and complications during osteosynthesis were the reasons. The group of patients treated via the intraoral approach showed less favourable results radiologically, clinically, and as judged by the patients' subjective feelings. Especially axiographical examination of the latter fractures revealed a restricted translation indicating that the fractures had not healed primarily. CONCLUSION: In order to avoid complications, the only fractures which should be treated intraorally are those which allow exact reduction even under the conditions of a limited view and reduced possibilities of surgical manipulation during reduction. This applies in general to fractures of the mandibular condyle with a laterally displaced condyle and a shortened ascending ramus. For all other dislocated or displaced fractures, extraoral reduction and osteosynthesis are the methods of choice.

Ultrasound aided pin fixation of biodegradable osteosynthetic materials in cranioplasty for infants with craniosynostosis.

AIM: Biodegradable osteosynthesis materials are often used for fixation of bone fragments when repairing craniosynostoses. When compared with titanium plates they have the disadvantage of difficult handling and time-consuming thread cutting. A new method of using resorbable pins inserted with the aid of ultrasound (bone welding) and not requiring thread cutting was applied in patients for the first time. METHOD: In eight patients with craniosynostoses, the biodegradable material Resorb-X was fixed with resorbable pins inserted with the aid of ultrasound. The patients were followed up for 12 months. RESULTS: Pin fixation was stable in all cases. The time required for applying the osteosynthesis materials was reduced by about 50% since handling of the material was easier and no thread cutting was required. CONCLUSIONS: Due to fixation in cortical as well as cancellous bone ultrasound aided fixation using resorbable osteosynthesis materials is more stable than screw fixation. The time required for application is considerably shortened as no thread cutting is required.

Bone welding--a histological evaluation in the jaw.

The expansion of biodegradable osteosynthesis systems in clinical application correlates well to the progress in development of new materials as to the improvement of application methods. One of those new application methods is the ultrasound-aided insertion of Resorb-X pins. The aim of this study was the histological evaluation of possible thermal damage to bone due to the ultrasound insertion. For this purpose, condylar neck fractures in 12 sheep were produced, repositioned and fixed by Resorb-X plates and pins. The animals were sacrificed in two groups, one after 2 weeks and one after 9 weeks. The bone-pin interlinkage and the structure of the bone were histologically evaluated. After 2 weeks a tight bone-polymer interlinkage was seen. Neither a pronounced foreign body reaction nor an interposition of fibrous tissue at the interface or a thermally induced necrosis was observed. The late phase of wound healing after 9 weeks showed pathomorphological characteristics within the normal range of bone healing. The bone seemed to be free of any alteration caused by process engineering. We conclude that thermal stress caused by ultrasound-aided pin insertion does not lead to cellular reaction in the bone. The fast and easy application of this improved biodegradable osteosynthesis system will bring a clear advantage in clinical use.

A comparison of MRI, radiographic and clinical findings of the position of the TMJ articular disc following open treatment of condylar neck fractures.

We examined the position and function of the articular disc after open treatment of condylar fractures by comparing magnetic resonance images (MRI) and radiographs with clinical data. MRI and radiographs were taken after treatment of 28 patients with 33 fractures of the mandibular condyles. In all cases, the disc was located in the fossa after open reduction and internal fixation (ORIF). The MRI, radiographic and clinical findings did not correlate, and damage to the temporomandibular joint (TMJ) could be seen more clearly on MRI than on clinical or radiographic examination. Damage to soft tissues seen on MRI after treatment was more pronounced in dislocated than in displaced fractures.

Resorbable poly(D,L)lactide plates and screws for osteosynthesis of condylar neck fractures in sheep.

We made osteotomies in the condylar neck in 12 adult sheep to simulate fractures, and joined the two ends with 2 poly(D,L)lactide (PDLLA) plates and 8 PDLLA screws 2mm in diameter. The animals were killed after 2, 6, and 12 months and bony healing was assessed macroscopically and histologically. The plates and screws remained intact and there was no displacement of the bony ends. The degrading plates, which were still visible in the specimens after 6 months, had been replaced by bone. At 12 months the PDLLA had been resorbed with no foreign body reaction and no resorption of underlying bone. The articular discs showed no signs of degeneration.

Site-Specific Variations in Bone Mineral Density under Systemic Conditions Inducing Osteoporosis in Minipigs.

Osteoporosis is a systemic bone disease with an increasing prevalence in the elderly population. There is conflicting opinion about whether osteoporosis affects the alveolar bone of the jaws and whether it poses a risk to the osseointegration of dental implants. The aim of the present study was to evaluate the effects of systemic glucocorticoid administration on the jaw bone density of minipigs. Thirty-seven adult female minipigs were randomly divided into two groups. Quantitative computed tomography (QCT) was used to assess bone mineral density BMD of the lumbar spine as well as the mandible and maxilla, and blood was drawn. One group of minipigs initially received 1.0 mg prednisolone per kg body weight daily for 2 months. The dose was tapered to 0.5 mg per kg body weight per day thereafter. The animals in the other group served as controls and received placebo. QCT and blood analysis were repeated after 6 and 9 months. BMD was compared between the two groups by measuring Hounsfield units, and serum levels of several bone metabolic markers were also assessed. A decrease in BMD was observed in the jaws from baseline to 9 months. This was more pronounced in the prednisolone group. Statistically significant differences were reached for the mandible (p < 0.001) and the maxilla (p < 0.001). The administration of glucocorticoids reduced the BMD in the jaws of minipigs. The described model shows promise in the evaluation of osseointegration of dental implants in bone that is compromised by osteoporosis.

Commentary regarding the publication "Fractures of the mandibular condyle--a review of 466 cases. Literature review, reflections on treatment and proposals" by N. Zachariades et al.

The paper by Zachariades et al. presents a considerable contribution with regards to the epidemiology of condylar fractures. Hence, it is not possible to draw conclusions from this study with regards to the indication of open reduction or closed treatment. Only well-documented prospective and, if possible, randomized studies will be able to help us in the fracture. In the first prospective randomized study [Eckelt U, Schneider M, Erasmus F, Gerlach KL, Kuhlisch E, Loukota R, Rasse M, Schubert J, Terheyden H: Open versus closed treatment of fractures of the mandibular condylar process - a prospective randomized multi-centre study. J Cranio Maxillofac Surg 34: 306-314, 2006], advantages were observed for the open reduction and fixation of displaced fractures with stable osteosynthesis.