Osseointegration of SLActive implants in diabetic pigs.

OBJECTIVES: Diabetes mellitus is currently classified as a relative contraindication for implant treatment because of microangiopathies with the consequence of impaired bone regeneration and higher rates of implant failure. The study aim was to investigate peri-implant bone formation in a diabetic animal model in comparison to healthy animals and to evaluate the differences between conventional (SLA(®) ) and modified (SLActive(®) ) titanium implant surfaces on osseointegration. MATERIAL AND METHODS: Each six implants were placed in the calvaria of 11 diabetic and 4 healthy domestic pigs. At 30 and 90 days after implant placement, the bone-to-implant contact (BIC) and bone density (BD) were appraised. Additionally, the expression of the bone-matrix proteins collagen type I and osteocalcin was evaluated at both points in time by using immunohistochemical staining methods. RESULTS: Overall, BIC was reduced in the diabetic group at 30 and 90 days. After 90 days, the SLActive(®) implants showed significantly higher BICs compared with the SLA(®) implants in diabetic animals. Peri-implant BD was higher in the SLActive(®) group at 30 and 90 days in healthy and diabetic animals. Collagen type I protein expression was higher using SLA(®) implants in diabetic pigs at 30 days. Values for osteocalcin expression were not consistent. CONCLUSIONS: The results indicate the negative effect of untreated diabetes mellitus on early osseointegration of dental implants. The modified SLA(®) surface (SLActive(®) ) elicited an accelerated osseointegration of dental implants, suggesting that a better prognosis for implant treatment of diabetic patients is possible.

Biofunctionalization of the implant surface with different concentrations of a synthetic peptide (P-15).

OBJECTIVE: This study aimed at identifying the ideal concentration of a biofunctional surface coating of dental implants with a synthetic peptide (P-15). In a previous study, P-15 was shown to enhance osseointegration parameters. MATERIAL AND METHODS: Implants (modified ANKYLOS(®) A8; FRIADENT Plus(®) surface) with five different concentrations (0-400 µg/ml) of a P-15 coating as well as uncoated controls were inserted in the frontal bone of 45 adult domestic pigs. The histomorphometric and microradiographic findings for the coated implants were compared to those for the uncoated ones after 7, 14, and 30 days. RESULTS: No significant differences were observed comparing the peri-implant bone density between the coated and uncoated implants The bone-to-implant contact, as the primary histological parameter for osseointegration, showed high rates for all surfaces investigated (between 73.3 ± 17.9% for the control and 81.9 ± 15.2% for P15 20 µg/ml after 30 days). CONCLUSIONS: No significant benefit on osseointegration of a biofunctional P-15 coating of dental implants could be displayed in the present study.

i.lect, a pre-graduate education model of implantology.

OBJECTIVE: In 2008, a consensus meeting of the Association for Dental Education in Europe stated that dental implant treatment represents a popular treatment alternative and, therefore, it should be an integral part of dental student pre-graduate education. In 2009, the Friedrich-Alexander University, Erlangen-Nuremberg implemented a voluntary, structured, education program for pre-graduate dental students, called 'i.lect'. The present study evaluated the effectiveness of the i.lect program. METHODS: Concurrent to the dental curriculum, the i.lect program provides 200 hours in 3 years of theoretical and practical education on all aspects of modern dental implantology. We recruited dental students in the i.lect program and additionally students from 15 other universities that voluntarily participated in a single, 3-day implantology camp (R = 58). To demonstrate their knowledge on dental implant issues, both student groups completed a written examination that covered 'Basic information and materials of implantology', 'Implant planning' and 'Soft tissue management'. RESULTS: The students in the i.lect program achieved higher scores than students from the implantology camp on questions concerning 'basic implantology' and 'implant planning'. CONCLUSION: The results indicated that the structured i.lect undergraduate curriculum enhanced individual knowledge in the specific field of implantology. This program could have pilot character for use in other universities.

Biofunctionalization of titanium implants with a biomimetic active peptide (P-15) promotes early osseointegration.

OBJECTIVES: The early stages of peri-implant bone formation play an essential role in the osseointegration and long-term success of dental implants. By incorporating bioactive coatings, this biofunctionalization of implant surfaces may enhance the attachment of the implant to the surrounding bone and stimulate bone regeneration. MATERIAL AND METHODS: To demonstrate faster osseointegration, the surfaces of dental implants were grit-blasted and acid-etched. They were then coated with hydroxyapatite (HA) and experimental implants were further coated with a biomimetic active peptide (P-15) in one of two concentrations. These biofunctionalized samples and controls with no peptide were placed in the forehead region of 12 adult pigs. Six animals were evaluated for a period of 14 or 30 days. RESULTS: Histomorphometric analysis demonstrated that the implants with the high concentration of P-15 had significantly higher percentage of bone-to-implant contact (BIC) at 14 (P=0.018) and 30 (P=0.015) days compared with the other groups. Both concentrations of P-15 showed increased peri-implant bone density compared to the control group at 30 days. CONCLUSION: Biofunctionalization of the implant surface with a biomimetic active peptide leads to significantly increased BIC rates at 14 and 30 days and higher peri-implant bone density at 30 days.

Experimental peri-implant mucositis around titanium and zirconia implants in comparison to a natural tooth: part 2-clinical and microbiological parameters.

The aim of this study was to assess the clinical and microbiological parameters around dental zirconia and titanium implants compared with natural teeth during experimental plaque accumulation. Clinical parameters were evaluated (gingival index, plaque index, bleeding on probing, and probing pocket depth). Microbiological samples were analyzed for total bacterial cell counts, as well as Tannerella forsythia and Prevotella intermedia counts. A statistically significant difference over time was observed in the groups in terms of the gingival index (P<0.001), plaque index (P<0.001), and bleeding on probing (P=0.039). The lowest mean total number of bacterial cells was measured around the teeth, followed by the zirconia implants; the highest values were found around the titanium implants. T. forsythia and P. intermedia values showed significant changes over time and sessions around the titanium implants. Compared to the soft tissues around zirconia implants and the teeth, those around titanium implants developed a stronger inflammatory response to experimental plaque accumulation in terms of the total number of bacterial cells and T. forsythia and P. intermedia values.

[Enophthalmos correction in complex orbital floor reconstruction : computer-assisted, intraoperative, non-contact, optical 3D support]. / Enophthalmuskorrektur bei komplexer Orbitarekonstruktion : Computerassistierte, intraoperative, berührungsfreie, optische 3D-Unterstützung.

In the case of displacement of the globe such as enophthalmos induced by trauma, the patient is affected on both counts: function and aesthetics. To prevent double vision or conspicuous asymmetry, exact correction of the globe position is required. The aim of this case report is to demonstrate an intraoperative computer-assisted, non-contact, optical 3D procedure for identification of the globe position to aid in placing the eyeball in the position required in complex reconstruction of the orbital floor. A 33-year-old man presented with a sunken eye on the right side in the horizontal and vertical plane 6 months after having undergone surgery elsewhere for a zygomatico-orbital fracture, also including the orbital floor. The patient was affected by double vision and a noticeable defective globe position. In planning the correction of the globe position, a three-dimensional image of the face with opened eyes was made with the optical sensor. Automatic comparison of symmetry revealed enophthalmos of 4 mm on relative en- and exophthalmometry. The decision was made to lift the orbital floor with a split calvarial bone graft. During surgery the position of the globe was also controlled by the three-dimensional optical technique. At the end of surgery there was exophthalmos of 1 mm. Six weeks after surgery the patient was not affected by any double vision. After 3 and 24 months enophthalmos was 1 mm. This case demonstrates how the non-ionizing, non-contact, optical 3D technique can help in planning, intraoperative transformation, and clinical monitoring to identify the correct position of the corneal vertex in complex orbital floor reconstruction.

[Computer-assisted orbital floor reconstruction. Use of a CAD/CAM implant with intraoperative contact-free 3D endo- and exophthalmometry]. / Computerassistierte Enophthalmuskorrektur. Nutzung eines CAD/CAM-Implantats unter intraoperativer, berührungsfreier 3D-en- und exophthalmometrischer Kontrolle.

Pronounced enophthalmos can restrict patients both functionally and aesthetically. Typical symptoms are double vision on both eyes and obvious asymmetry, both of which were present in the 67-year-old male patient presented in this paper. The resulting data of computed tomography was used to fabricate a patient specific ceramic implant for reconstruction of the left orbital floor with an enophthalmos of 4mm. During the surgery the implant fitted anatomically correct, but exophthalmos occurred. The implant needed to be regraded and recontoured in the dorsal fraction, so that overcorrection could be reduced. With the assistance of optical 3D en- and exophthalmometry during surgery, the position of the cornea vertex was reproducible measured. At the end of surgery, exophthalmos was 1.5 mm. After 12 months, enophthalmos of only 1mm exists. This case displays the combination of a patient specific fabricated implant for reconstruction of the orbital floor with optical 3D-en-and exophthalmometry to correct enophthalmos with a high degree of accuracy. Therefore these two techniques in combination should be used when complex corrections of enophthalmos are needed.

Evaluation of peri-implant bone levels and soft tissue dimensions around zirconia implants-a three-year follow-up study.

The aim of this study was to measure bone levels around zirconia implants during follow-up of up to 3 years. Additionally, the effect of clinical contact point positions on the papilla deficit was evaluated. Eighty-one patients with 105 zirconia implants were examined at the 3-year follow-up. Bone levels were measured on the date of implant placement and at 3 months, 1year, and 3 years thereafter. Distances between the first bone-implant contact and the contact point of the crowns and between the bone level at the adjacent tooth and the contact point of the crowns were assessed. The effect of the clinical contact point position on the papilla deficit was also assessed. Significant reductions in the distances between the bone-implant contact and the implant shoulder, as well as the contact point of the crowns, and between the bone level at the adjacent tooth and the contact point of the crowns, were found. A significant association was found between the papilla deficit and the height of the contact point. Implant survival was 100% and implant success was 95.4%. While zirconia implants presented little bone loss up to 1year, significant bone apposition was observed up to 3years. Low contact points correlated with full papillae, whereas high contact points were associated with a papilla deficit.

The effect on bone regeneration of a liposomal vector to deliver BMP-2 gene to bone grafts in peri-implant bone defects.

Successful bone-implant osseointegration in large peri-implant bone defects is often difficult, even through autologous bone grafting. Recently, cell-mediated regional gene therapy was introduced to deliver potent morphogens or growth factors in regenerative medicine. We applied liposomal vectors carrying bone morphogenetic protein (BMP)-2 cDNA directly into freshly created peri-implant bone defects on pig calvariae, with or without autologous bone graft. The BMP-2 gene was efficiently introduced into immigrating cells and trabecular cells lining the marginal bone surrounding the bony defect. After 1 week, abundant BMP-2 protein was detected throughout the peri-implant bone defect by immunohistochemistry. At 4 weeks, BMP-producing cells were still present in the defect and peri-implant area, which significantly enhanced new bone formation, compared with the control groups. Interestingly within a week of BMP-2 gene delivery with bone grafts, most osteoblastic cells lining the grafted bone chips also produced BMP-2. Particulated bone was immediately reorganized into newly formed trabecular bone. Grafted bone without BMP-2 gene delivery was still scattered and new bone matrix formation was not detected until 4 weeks after bone grafting. In conclusion, direct application of the BMP-2 gene using a liposomal vector enhanced bone regeneration in a bony defect and gene delivery combined with bone graft could induce a rapid osseointegration of the bone-implant interface at earlier stage.

Evaluation of substitutes for bone: comparison of microradiographic and histological assessments.

We created defects of standard size in the frontal bones of adult pigs and filled them with four different materials. On six occasions (at 1, 2, 4, 8, 12, and 26 weeks), samples were harvested, and evaluated by computing microradiographic images. We examined the specimens histologically as controls. After insertion of anorganic materials, microradiographic evaluation was easy and precise, and there were no significant differences between them and the histological controls (p=0.2). A quantitative evaluation of chemically sterilised bone by computer was not possible for more than 4 weeks.

Search for a reliable model for bisphosphonate-related osteonecrosis of the jaw: establishment of a model in pigs and description of its histomorphometric characteristics.

The pathogenesis of bisphosphonate-related osteonecrosis of the jaw (BRONJ) remains unknown, and the development of a reliable experimental model would help to improve our understanding of it. We used 12 domestic pigs of which 6 made up the experimental group and were treated with zoledronate 4mg intravenously weekly for 5 weeks, while the control group (n=6) were given no drugs. On day 60 the right second maxillary and mandibular third molars were extracted. Thirty days later 3 animals in each group were killed; the rest were killed 90 days later. Histopathological specimens from the extraction sites were analysed for bone density, collagen architecture, density of osteons, and the amount of non-mineralised bone. Bone density, amount of non-mineralised bone, and density of osteons differed significantly between the 2 groups (p<0.001 in each case), but the chromatic pattern dictated by the collagen architecture did not. Our results correspond to the observations that have been made in patients with BRONJ, which means that the histomorphometric conditions seen in patients can be reproduced in this experimental setting.

Expression of bone matrix proteins during de novo bone formation using a bovine collagen and platelet-rich plasma (prp)--an immunohistochemical analysis.

This animal study (domestic pig) examined the bone formation after filling defined defects with autogenous bone or a collagen lyophilisat in combination with Platelet-rich-plasma (PRP) by evaluating bone matrix proteins. Six groups, both materials with and without PRP in two concentrations (+ 1, + 2) were compared to untreated bone by means of immunohistochemistry at 2, 4, 12 and 26 weeks. BMP-2 expression was increased at 2 weeks in the collagen + 1 group and after 4 weeks in the collagen + 1 and + 2 group. Collagen-I expression was increased at 2 weeks in all collagen groups. After 4 weeks raised levels were observed after adding the higher concentrated PRP to bone and the collagen material. Osteocalcin expression was enhanced at 2 weeks in all collagen groups and the autogenous bone + PRP1 group, after 4 weeks in the bone and collagen + 2 groups. At 12 weeks higher values were observed after adding higher concentrated PRP to bone. Osteonectin and especially osteopontin were confirmed to be effective markers of early bone formation in all specimens. The described setting allows to combine established techniques (microradiography, light microscopy) with approaches to explore the underlying biology (immunohistochemistry) on the same specimen.

Establishment of a new pull-out strength testing method to quantify early osseointegration-An experimental pilot study.

OBJECTIVES: The animal study aims to evaluate a new experimental model for measuring sole the influence of the surface characteristics independent from implant macro-design on the level of osseointegration by registering the pull-out strength needed for removal of experimental devices with different surfaces from artificial defects. MATERIAL AND METHODS: Seventy-two test bodies (36 with the FRIADENT(®) plus surface, 36 with the P15/HAp biofunctionalized surface) were inserted in six adult domestic pigs with artificial calvarial defects. The experimental devices were designed to fit in the defects leaving a gap between the test body and the local bone. After 21 days of healing, the animals were sacrificed and the test bodies were pulled out with a standardised reproducible pull-out device measuring the pull-out strength. The pull-out strength for both groups was compared. RESULTS: Twenty-one days after insertion a mean force of 412 ± 142 N for the P15/HAp group and 183 ± 105 N for the FRIADENT(®) plus group was measured for the removal of the specimens from the calvarial bone. The difference between the groups was statistically significant (p < 0.0001). CONCLUSION: The experimental set-up seems to be a suitable method when measuring the impact of implant surfaces on the early stage of osseointegration.

Soft tissue findings above submerged titanium implants--a histological and spectroscopic study.

The aim of this study was to check the titanium level within the muco-periosteal flaps covering submerged titanium implants. The investigated material included 38 biopsies taken after 2.4-18 months (mean: 5.9) after implant insertion. Due to the evident time delay between implantation and taking the biopsy any influence of the implantation trauma itself was excluded. The implants came from the following producers: HaTi (Matthys, Switzerland), ITI (Straumann, Switzerland) and Branemark (Nobelbiocare. Sweden). The surface areas of these implants differ in size and structure. A comparison between the titanium impregnation of the investigated biopsies did not demonstrate any remarkable influence of the surface differences. This can be explained by the fact that only the top diameter and not the implant surface as a whole was the contact area with the excised tissue. Titanium in the biopsies was analysed in terms of its effect histologically and regarding the titanium quantity by spectrophotometry. Even the highest titanium contamination was without a negative effect on the muco-periosteal cover flaps. A correlation between time delay between implantation and biopsy or of the titanium amount and tissue reactions was not demonstrable. In summary, the results again highlighted the biological acceptance of titanium.

De novo bone formation using bovine collagen and platelet-rich plasma.

In order to regenerate critical-size bone defects, a variety of bone substitutes is used in addition to autogenous bone. The regenerative capacity of these bone substitutes is usually compared to the efficacy of autogenous bone known as the "golden standard". Different cytokines influence the regeneration process because of their morphogenic or mitogenic properties. Platelet-rich plasma (PRP), a platelet concentrate, is characterised by having a positive effect on wound healing, reducing bone graft resorption and increasing the density of bone transplants. This experiment was commenced with a view to studying the osseous defect regeneration after placing various combinations of "filler materials" in experimentally created defects in the forehead of adult pigs. Regeneration by means of grafted autogenous bone (Group 1) or a bovine collagen based medical device (Group 4) alone and combined with PRP in two concentrations (Groups 2, 3, 5 and 6) was evaluated by means of microradiography and light microscopy after 2, 4 and 12 weeks. The microradiographic and light microscopic findings showed that autogenous bone in combination with PRP (Groups 2 and 3) had a significant accelerating effect on early bone regeneration (2 weeks). This effect was not evident when PRP was added to the bovine collagen (Groups 5 and 6). When using the collagen alone, significantly higher mineralisation values were achieved after 2 and 4 weeks than when using autogenous bone alone. After a 12-week observation period, the existing differences between the healing processes in the various groups were more or less levelled out. In summary, the results of the study indicate that clinically autogenous bone, as expected, is the ideal defect filler. Combining autogenous bone with PRP did not provide significantly better results. The findings in the groups treated with bovine collagen indicate that its local application mimics the effect of autogenous bone and amplifies bone regeneration when comparing with the control defect.

Endosseous dental implants in orthodontic therapy.

This paper presents cases in which endosseous titanium implants are used in orthodontic treatment as an alternative method of providing anchorage, as well as solving prosthodontic problems, and shows that such an approach can be successful.

Oral findings associated with primary hyperoxaluria type I.

In the present paper we report the oral findings of a patient who was diagnosed with hyperoxaluria. Hyperoxalurias can basically be classified as primary and secondary, with the first being inborn errors of metabolism and the second a result of excessive oxalate intake. Primary hyperoxalurias form a rare group of metabolic diseases that are inherited in the autosomal recessive fashion. The affected genes code for specific hepatic enzymes that are involved in glyoxylate metabolism and their deficiency results in overproduction of oxalate. Two different types are described: Primary hyperoxaluria type I results from a deficiency of peroxisomal enzyme alanine-glyoxylate aminotransferase and the more rare type II from a deficiency of cytosolic enzyme D-glycerate dehydrogenase. Since oxalate is primarily excreted through the kidneys, abnormally high concentration of oxalate in the urine occurs. This can in turn result in recurrent kidney stones and parenchymal renal damage and end-stage renal disease (ESRD). Inability to further excrete oxalate through the kidneys leads to its deposition in various organs (oxalosis). Several oral findings have been described in patients with oxalosis, most important of whose are bone resorption in the jaws, external root resorption and rapidly progressive dental mobility, as well as dental pain associated with deposition of oxalate in the dentine and the pulp.

Topical use of platelet-rich plasma to influence bone volume in maxillary augmentation: a prospective randomized trial.

BACKGROUND AND OBJECTIVES: The atrophic posterior maxilla often requires restoration of the alveolar ridge due to a lack of bone quantity and quality before dental implant placement. The aim of this study was to verify the hypothesis that platelet-rich plasma (PRP) has an influence on bone density in the maxilla after sinus floor elevation in combination with autologous cancellous bone from the iliac crest. Therefore, a randomized, prospective, controlled trial was set up in two centres. STUDY DESIGN AND METHODS: Fifty-three patients who underwent osteoplastic bone grafting for sinus floor elevation were included. The intervention group was treated with defined concentrations of PRP in addition to transplanted bone. Bone biopsy was performed 4 months after augmentation. Bone volume was then measured using the histomorphometric parameter bone volume. RESULTS: The histomorphometric evaluation of the biopsies did not indicate superiority of any of the treatments in terms of bone volume. CONCLUSION: Topical use of PRP did not improve maxillary bone volume either clinically relevant or statistically significant compared to that in conventionally treated patients. The use of PRP to support bone regeneration cannot be recommended as a standard method for maxillary augmentation.

Preclinical animal study and clinical trail of modified extraoral craniofacial implants.

We report on our experience using a new endosseous implant designed to provide sufficient retention to various types of facial prostheses. In a preclinical animal experiment implants (N=12, 4 x 3.5 mm) were placed in the frontal calvarial region of nine adult pigs. The animals were sacrificed at 2, 4 and 8 weeks to evaluate the implant incorporation microradiographically. The clinical outcome and patient satisfaction of implant-retained prostheses were evaluated in a group of 10 patients with facial defects by using clinical assessment and standardized questionnaires for patients and relatives. In the prospective clinical study 33 identical modified implants for extraoral anchorage were placed for the fixation of various prostheses in the midfacial (eye, nose) and ear regions in the course of a clinical trial and observed over a follow-up period of 34 months. The bone-implant contact in the animal experiment reached 31% (+/-2) at 2 weeks, 39% (+/-1) after 4 weeks and 51% (+/-5) at 8 weeks. In the clinical trial, no implants were lost and all implants remained osseointegrated as confirmed clinically and radiographically, providing a stable prosthetic restoration. The analysis of the questionnaire indicates an improvement of the quality of life of patients with respect to aesthetic and psychological well-being. The results demonstrate that extraoral implants not only achieve sufficient osseointegration but also show good clinical handling and easy fixation possibilities for prosthetic anchorage.