Biomedical subjects

Georg Watzek

Publications and source records attributed to Georg Watzek.

At least 19 recordsLinked to original sources

PubMed2006

Age-related changes of cell outgrowth from rat calvarial and mandibular bone in vitro.

AIM: To establish whether within an autograft ageing has an impact on the number of cells capable of responding to growth and differentiation factors released at defect sites. MATERIAL AND METHODS: The number of cells that grow out from calvarial and mandibular explants of rats 6 weeks and 9 months of age was evaluated and their response to mitogenic, chemotactic, and differentiation factors was characterized in vitro. The cell number was determined by automated counting, proliferation was evaluated by measuring the amount of (tritiated) (3)[H]thymidine incorporated into the DNA, and migration was assessed with the modified Boyden chamber assay. Alkaline phosphatase activity served as a marker of osteogenic differentiation. RESULTS: A confluent layer of cells was observed in mandibular and calvarial explant cultures derived from young rats within 10 days, while only sporadic cells were counted in cultures from adult animals. The number of cells derived from calvarial and mandibular bone of young rats was nine and five times higher, respectively, than that in explants from adult rats. Cells isolated from calvarial and mandibular explants responded to platelet-released supernatant by increased proliferation and migration in both age groups. Upon incubation with bone morphogenetic protein (BMP-6), the alkaline phosphatase activity of calvaria-derived cells from both age groups was higher than in unstimulated controls. Only one sample of cells derived from mandibular explants showed responsiveness to BMP-6 in the young age group, whereas none of the cell samples responded to BMP-6 in the adult age group. CONCLUSION: The number of cells capable of growing out from mandibular and calvarial grafts in vitro is lower in adult animals than in young animals. However, bone-derived cells from both young and adult rats respond to growth and differentiation factors present at defect sites, while there are topographic differences in the responsiveness to BMP-6.

Age Factors↗

PubMed2006

Activated platelets retain their potential to induce osteoclast-like cell formation in murine bone marrow cultures.

Supernatants immediately obtained after platelet activation can induce osteoclast-like cell formation in murine bone marrow cultures. Here we report that activated platelets retain their potential to induce osteoclast-like cell formation over a 3-day period with repeated washing, when co-cultured with murine bone marrow cells. Supernatants obtained from washed platelets 3 days following their activation with thrombin, caused the differentiation of haematopoietic progenitors into osteoclast-like cells. The platelet-derived soluble factor(s) responsible for the induction of osteoclastogenesis can be retained in an ultrafilter with a nominal molecular weight limit of 10 kDa, and loose their activity when incubated at 99 degrees C. Indomethacin, which inhibits cyclooxygenase activity, and osteoprotegerin, a decoy receptor for receptor activator of nuclear factor-kappaB ligand (RANKL), suppressed the formation of osteoclast-like cells in this model. The in vitro findings presented here suggest that activated platelets can induce osteoclast-like cell formation via a prostaglandin and RANKL-dependent mechanism over a time period corresponding to the existence of a blood clot.

Animals↗

PubMed2006

Osteogenic differentiation induced by bone morphogenetic proteins can be suppressed by platelet-released supernatant in vitro.

Both bone morphogenetic proteins (BMPs) and growth factors released from activated platelets both occur at sites of bone regeneration but their functional relationship to regulate the temporal and spatial sequence of cellular events is not well defined. Here we investigated whether supernatants derived from activated platelets can modulate the response of the osteogenic cell line MC3T3-E1 to BMPs, and whether BMPs have an effect on MC3T3-E1 cells stimulated with platelet-released supernatant. Platelet-released supernatant suppressed BMP-2-, BMP-6-, and BMP-7-induced osteogenic differentiation of MC3T3-E1 cells, as indicated by the significant decrease in alkaline phosphatase activity and lower levels of osteocalcin transcripts, whereas BMP-2, BMP-6, and BMP-7 did not modulate migration and proliferation of MC3T3-E1 cells, which were stimulated with platelet-released supernatant. Osteogenic differentiation in response to BMPs was not affected after precultivation of MC3T3-E1 cells with platelet-released supernatant. These data suggest that activated platelets can provide a microenvironment that temporarily suppresses the differentiation of osteogenic cells in the presence of BMPs. Future strategies to stimulate bone regeneration should take the suppression of BMP-induced osteogenic differentiation during the existence of the blood clot into account.

3T3 Cells↗

PubMed2006

Soft tissue around three different implant types after 1.5 years of functional loading without oral hygiene: a preliminary study in baboons.

The purpose of this study was to determine the peri-implant soft tissue dimension (PSD) and peri-implant bone level (BL) of dental implants with different designs and surface modifications after functional loading without oral hygiene. Three types of dental implants were placed in the posterior jaws of adult baboons, three of the same design per quadrant, and fitted with fixed partial dentures. After 1.5 years of functional loading and plaque accumulation, all implants showed severe peri-implant mucositis and comparatively high BL. A histomorphometric evaluation of the sulcus depth (SD), the dimension of the junctional epithelium (JE) and the connective tissue contact (CTC) resulted in no significant differences between the three implant designs, neither in the maxilla nor in the mandible (P>0.05). The sum of SD, JE and CTC forming the PSD was nearly the same in the maxilla (commercially pure titanium, CpTi: 3.5 mm 2.9/4.1 confidence interval (CI); titanium plasma sprayed (TPS): 3.5 mm 2.9/4.2 CI; sand blasted acid-etched (GBAE): 3.2 mm 2.7/3.9 CI) and in the mandible (CpTi: 3.2 mm 2.6/3.8 CI; TPS: 3.2 mm 2.6/3.8 CI; GBAE: 3.2 mm 2.7/3.9 CI; P>0.05). There was no difference in BL around the three implant designs (maxilla: CpTi: 0.9 mm 0.5/1.6 CI; TPS: 0.9 mm 0.5/1.5CI; GBAE: 0.9 mm 0.5/1.6 CI; mandible: CpTi: 0.8 mm 0.5/1.2 CI; TPS: 0.6 mm 0.4/0.9 CI; GBAE: 0.7 mm 0.5/1.1 CI; P>0.05). Overall, the data presented did not show any significant differences in peri-implant soft tissue conditions in baboons. Moreover, plaque accumulation and propagation of peri-implant mucositis after 1.5 years of functional loading was not influenced by implant design and surface modifications in baboons.

Acid Etching, Dental↗

PubMed2006

Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis.

To investigate the behaviour of early loaded palatal implants when observed with resonance frequency analysis (RFA). Twenty patients (seven males and 13 females, mean age 26.4 years) received one palatal implant each (length: 4 mm, diameter: 3.3 mm; Orthosystem) for maximum orthodontic anchorage. The implants' stability was observed by RFA. Measurements were carried out at the time of surgery, after first orthodontic loading and subsequently once a week over a period of 12 weeks. Two palatal implants were lost. The other 18 remained stable. The average period from insertion to first loading was 6.7+/-0.8 days. The mean orthodontic force applied was 272.2+/-73.2 cN. The implant stability quotient (ISQ) value at the time of surgery averaged 69.4+/-3.9. The mean ISQ value 6.7 days after insertion was 69.8+/-3.6. Twelve weeks post-surgery the mean ISQ value was 69.8+/-3.5. A statistically significant decrease in stability was observed after 2 and 3 weeks post-surgery (P=0.005 and 0.04). The behaviour of early loaded palatal implants showed an initial decrease of the ISQ values. From 6 weeks post-surgery onward the ISQ values increased. Within the limitations of this study, the results suggest that the healing time of palatal implants reported in the literature (12 weeks) should be discussed. An orthodontic loading of palatal implants 6 weeks post-surgery with a force up to 400 cN seems to be justified. Yet further investigations are necessary to evaluate the behaviour of early loaded palatal implants considering observation periods of over 12 weeks.

Adolescent↗

PubMed2006

Radiological and clinical follow-up of machined- and anodized-surface implants after mean functional loading for 33 months.

The purpose of this retrospective study was to compare peri-implant bone loss and mucosal conditions around machined-surface (MS) and anodized-surface (AS) interforaminal implants in the mandible at least 30 months after placement. Fifty patients, each treated with four interforaminal screw-type implants consecutively, were included. Thirty-one patients (62%) with a total number of 124 implants (64 MS and 60 AS implants, both Brånemark type MKIII) were available for follow-up. Rotational panoramic radiographs were used for evaluating marginal bone loss. Clinically, marginal plaque index (mPI), bleeding on probing (BOP) and pocket probing depth (PPD) were evaluated. AS implants showed significantly less marginal bone loss than MS implants (-1.17+/-0.13 vs. -1.42+/-0.13 mm; P=0.03). Marginal bone loss around distal implants was less pronounced at AS implants (-1.05+/-0.14 mm) when compared with MS implants (-1.46+/-0.14 mm; P=0.05). Within the smoking group, there was less peri-implant bone loss around AS implants than around MS implants (-1.08+/-0.27 vs. -1.83+/-0.2; P=0.04). No differences between MS and AS implants were found with respect to mPI (57% vs. 67%), BOP (21% vs. 17%) and mean PPD (2.59+/-0.29 vs. 2.56+/-0.28 mm). Overall, both types of implants, in combination with bar-supported overdentures, can produce excellent long-term results in the interforaminal edentulous mandible with less peri-implant bone loss around rough implant surfaces, which had beneficial effects at distal implants and in smokers.

Aged↗

PubMed2006

Cathepsin K levels in the crevicular fluid of dental implants: a pilot study.

OBJECTIVE: To determine the concentration of cathepsin K secreted into the crevicular fluid around dental implants and its correlation with clinical parameters of healthy implants and implants showing clinical signs of peri-implantitis. MATERIAL AND METHODS: Nineteen patients with 40 implants with and without peri-implantitis were enrolled in the study. Peri-implantitis was diagnosed by the pocket probing depth (PD), the modified bleeding index (MBI), the modified plaque index (MPI) and by radiographic signs of bone loss. Gingival crevicular fluid collected from the buccal and lingual sites was adsorbed to filter strips. Cathepsin K levels and total protein within the crevicular fluid were determined by immunoassay and the bicinchoninic method, respectively. RESULTS: Cathepsin K per filter strip normalized to the time of collection was 10.1 (0-33.5) pmol/sample around control implants and 22.4 (3.7-56.3) pmol/sample in the peri-implantitis group. The difference between the medians was significant (p < 0.01). Absolute cathepsin K levels in the crevicular fluid of all implants investigated showed a positive correlation with PD (R = 0.25; p = 0.03), MPI (R = 0.28; p = 0.01) and MBI (R = 0.32; p < 0.01). Absolute cathepsin K levels in the crevicular fluid also correlated with the adsorbed volume of gingival crevicular fluid (R = 0.51; p < 0.01). When normalized to the adsorbed volume of gingival crevicular fluid, the concentration of cathepsin K was 2.2 (0.01-6.4) nM around control implants and 1.7 (0.4-4.6) nM in the peri-implantitis group (p = 0.33). Patients' age correlated with sample volume and with cathepsin K normalized to the adsorbed volume of gingival crevicular fluid (R = 0.39; p < 0.01). Moreover, significant differences between male and female (p < 0.01, p < 0.01), and between mandible and maxilla (p < 0.05, p < 0.01), but not between buccal and lingual sites (p = 0.99, p= 0.93), were observed when analysed for the parameters adsorbed volume and absolute cathepsin K levels. CONCLUSION: Clinical parameters of peri-implantitis are associated with a higher amount of cathepsin K and a higher volume adsorbed to filters strips. To establish cathepsin K as a biochemical parameter to monitor peri-implant tissue health, age, sex and collection site should be considered to avoid interfering influences because of sample inhomogenity. Also a prospective study over time including more patients would be necessary.

Adult↗

PubMed2006

Soluble RANKL in crevicular fluid of dental implants: a pilot study.

BACKGROUND: Receptor activator of NF-kappaB ligand (RANKL), a member of the tumor necrosis factor superfamily, is a key mediator of osteoclast formation, activation, and survival. Thus, it is reasonable to hypothesize that there might be a functional relationship between RANKL expression and peri-implantitis. PURPOSE: This pilot study was performed to determine the reference levels for soluble RANKL (sRANKL) in peri-implant crevicular fluid and to correlate them with the clinical parameters associated with inflammatory reactions and bone destruction. MATERIALS AND METHODS: The clinical parameters probing depth (PD), modified bleeding index (MBI), and modified plaque index (MPI) served as indicators for bone resorption and inflammation. Exclusion criteria for calculations were the detection limit of the immunoassay and the minimum acceptable crevicular volume for measurement. From the 84 collected samples of 16 patients, 30-84 years of age, with a total of 19 implants, 29 met these criteria. The absolute amount of sRANKL within crevicular fluid adsorbed to filter strips was a median of 0.18 femtomol (fmol; range, 0.08-0.53) and 0.26 nM (range, 0.09-1.21) when normalized by volume. PD was 4 mm in median and varied within a range between 2 and 12 mm. RESULTS: Absolute amounts of sRANKL showed no correlation with the adsorbed volume and the clinical parameters PD, MBI, and MPI. When sRANKL was normalized by volume, no correlation with the clinical parameters PD, MBI, and MPI was observed either. The patients' age was not associated with total sRANKL and the concentration of RANKL within crevicular fluid. Absolute levels of sRANKL and sRANKL concentration did not show any differences based on the sampling sites buccal and lingual, or on the patients' gender. A significant difference in sRANKL concentration was detectable when samples from maxillary implants (0.31 nM median; range, 0.12-1.21) were compared with samples from mandibular implants (0.21 nM median; range, 0.09-0.6) (p=.03). Absolute levels of sRANKL were not different between the maxilla and the mandible. CONCLUSION: Given the limited sample size, our data provide a basis for future prospective longitudinal studies on the possible relevance of sRANKL as a prognostic marker in peri-implantitis, and for an understanding of the pathophysiologic process of the disease as a prerequisite for the design of treatment strategies.

Adult↗

PubMed2006

Bone marrow stromal cells of young and adult rats respond similarly to platelet-released supernatant and bone morphogenetic protein-6 in vitro.

BACKGROUND: Age-related changes in periodontal bone regeneration, osseointegration of dental implants, and graft consolidation are increasingly considered in treatment planning. This study was intended to show whether aging is associated with a diminished responsiveness of osteoprogenitor cells to growth and differentiation factors. METHODS: We compared the capacity of bone marrow stromal cells harvested from young and adult rats to proliferate, migrate, and differentiate into the osteogenic lineage following exposure to platelet-released supernatant (PRS) or bone morphogenetic protein-6 (BMP-6). Bone marrow stromal cells were isolated from 12 young rats aged 6 weeks and 12 adult rats aged 9 months. Proliferation was assessed by 3[H]thymidine incorporation, migration was evaluated with the Boyden chamber assay, and osteogenic differentiation was deduced from alkaline phosphatase activity. RESULTS: Irrespective of the donor age, bone marrow stromal cells showed increased mitogenic activity and chemotactic motility when exposed to PRS. Adult bone marrow stromal cells had higher alkaline phosphatase activities at baseline and upon incubation with BMP-6 than cells obtained from young animals. There was no difference between the two groups in the slope of the alkaline phosphatase activity curve following stimulation with BMP-6. CONCLUSIONS: The data demonstrate that, irrespective of their age, bone marrow stromal cells respond similarly to PRS and BMP-6 under in vitro conditions. These findings suggest that osteoprogenitor cells within the bone marrow of adult rats retain their juvenile potential to respond to growth and differentiation factors, which are released naturally or are applied therapeutically at sites of bone regeneration.

Aging↗

PubMed2005

Platelets can neutralize hydrogen peroxide in an acute toxicity model with cells involved in granulation tissue formation.

Platelets play a key role in the replacement of the blood clot with granulation tissue during the early steps of bone regeneration. We hypothesized that activated platelets can neutralize locally produced reactive oxygen species, thereby protecting cells involved in granulation tissue formation. The potential of platelet-released supernatant (PRS) to neutralize hydrogen peroxide (H(2)O(2)) was tested in an acute toxicity model with osteogenic, inflammatory, and endothelial cells. In the human fetal osteoblastic cell line 1.19 (hFOB), considerable morphological changes, cell shedding, and dysfunction of the respiratory chain were observed when cells were exposed to 3 mM H(2)O(2). Caspase-3 and poly-(ADP-ribose)-polymerase were not activated, suggesting that cell death occurred by necrosis. Preincubation of osteogenic cells, leukocytes, or endothelial cells with PRS decreased the acute toxicity of H(2)O(2). The capacity of platelets to release H(2)O(2)-detoxifying activity was retained for up to 72 h. Aminotriazole, an inhibitor of catalase, decreased the cytoprotective activity of PRS, whereas blocking of glutathione peroxidase by mercaptosuccinate had no effect. These results suggest that platelet-released catalase can rapidly neutralize cytotoxic amounts of H(2)O(2), a process that may play a role during the early stages of bone regeneration.

Blood Platelets↗

PubMed2005

Proliferation and osteogenic differentiation of cells from cortical bone cylinders, bone particles from mill, and drilling dust.

PURPOSE: The osteogenic potential of a graft is based on the parallel lines ability of cells to survive transplantation and to respond to local factors that stimulate new bone formation. Here we investigated the potential of cells that had grown out of porcine cortical bone grafts obtained by 3 preparation techniques to respond to mitogenic and osteogenic stimuli. MATERIALS AND METHODS: Bone grafts were harvested from 2 pigs. Cortical bone was taken in cylindrical form and ground in a bone mill or harvested via drilling and aspiration. RESULTS: Cell outgrowth was observed in all cortical bone cylinders, bone cylinders homogenized by mill, and 5 of 10 explants of bone dust collected upon drilling. After a 2-week culture period, the number of outgrown cells did not significantly differ among the 3 preparations. Bone cells showed increased proliferation in response to platelet-released supernatants as determined by 3 [H]-thymidine incorporation assay. When cultured under conditions that favor the expression of an osteogenic phenotype, the outgrown cells expressed alkaline phosphatase activity and transcripts of the osteoblast-specific marker osteocalcin. Individual cell preparations showed accumulation of mineral salts in their extracellular matrix. Bone cells also increased alkaline phosphatase activity in response to bone morphogenetic protein (BMP)-2, BMP-6, and BMP-7. The mitogenic and osteogenic response was obtained with cells from the mandible as well as from the maxilla, irrespective of the preparation technique. CONCLUSION: These data show that cortical bone grafts contain cells that have the ability to proliferate and differentiate into the osteogenic lineage, suggesting that these cells can contribute to bone regeneration following transplantation.

Alkaline Phosphatase↗

PubMed2005

Bony press-fit closure of oro-antral fistulas: a technique for pre-sinus lift repair and secondary closure.

PURPOSE: To evaluate the use of intra-oral bone grafts for closing chronic oro-antral fistulas (OAFs), for providing a sound basis for subsequent conventional sinus lifting and for preserving the teeth adjacent to OAFs. PATIENTS AND METHODS: Twenty-one patients with oro-antral fistulas of variable origin were treated with monocortical bone blocks harvested from the retromolar or interforaminal regions of the mandible. The preoperative treatment, the surgical procedure for both hard and soft tissue closure, and the postoperative management are reviewed in detail. RESULTS: Press-fit closure for repair of the bony sinus floor was sufficient in 17 patients. Four of them needed additional internal fixation. In all 21 patients adequate closure of the fistulas was obtained, although 3 patients (14.3%) developed wound dehiscences at the grafted sites, which healed by secondary intention. Meanwhile, 3 patients underwent successful sinus lifting. CONCLUSION: The use of monocortical bone grafts harvested at intra-oral donor sites is a safe and easy technique for repairing defects of the maxilla, especially OAFs in need of secondary closure. It provides a sound basis for subsequent conventional sinus lifting and preserves the teeth adjacent to OAFs.

Adult↗

PubMed2005

Alveolar ridge augmentation with a prototype trilayer membrane and various bone grafts: a histomorphometric study in baboons.

Barrier membranes have become a standard treatment option in alveolar ridge augmentation prior to implant placement. However, non-resorbable membranes require secondary surgery and resorbable membranes show an unfavorable degradation profile. The purpose of this study was to evaluate the potential of a slowly biodegradable/bioresorbable prototype trilayer membrane (PTLM) for supporting bone regeneration in alveolar ridge augmentation. Clinically relevant cavities were made 3 months after the extraction of the first and second molars in each jaw of six baboons. Each animal was treated with four different regimens: (1) autogenous bone block (ABB) alone, (2) ABB+PTLM, (3) deproteinized bovine bone mineral (DBBM)+PTLM and (4) no treatment. After 9 months, the baboons were sacrificed and block sections of the augmented area were subjected to histologic and histomorphometric analyses. Newly formed bone areas were determined at a distance of 1, 3, 7 and 10 mm from crestal. The data showed a well-preserved ridge profile at the membrane-protected sites, whereas non-protected bone blocks and control sites underwent severe resorption resulting in knife-edge ridge profiles. Significant differences were found between ABB+PTLM and ABB (P=0.0137-0.0232). DBBM+PTLM also produced a larger bone area compared with ABB alone (P=0.0396-0.0439). No significant difference in bone area was detectable between ABB+PTLM and DBBM+PTLM (P>0.05). The present study supports the use of the slowly biodegradable/bioresorbable PTLM with autografts and DBBM for lateral ridge augmentation in this type of bone defects.

Absorbable Implants↗

PubMed2005

Histologic and histomorphometric analysis of three types of dental implants following 18 months of occlusal loading: a preliminary study in baboons.

The purpose of this study was to determine the percentage of 'bone area' (BA) and 'bone-to-implant contact' (BIC) of dental implants with different designs and surface modifications after functional loading. Three types of dental implants with fixed partial dentures were placed in the posterior jaws of adult baboons (commercially pure titanium (CpTi) screws, grit-blasted acid-etched (GBAE) screws, and titanium plasma-sprayed (TPS) cylinders), three of the same design per quadrant. After 18 months of functional loading, all implants investigated were successfully integrated in the jawbone and histologic and histomorphometric analyses were carried out. Statistical evaluation was performed with a mixed model with data given as least-square means and standard errors of the mean (SEM). Histologically, direct BIC without connective tissue interposed between implant surfaces and peri-implant bone was seen. Analysis of BA within 1 mm around implants showed significant differences between CpTi (50.5%) and TPS (39.7%) (+/-2.72 SEM; P<0.01) in the maxilla. To account for the different implant designs, absolute BIC was calculated. Significant differences were found between CpTi (23.9 mm) and TPS (15.1 mm) and between GBAE (27.2 mm) and TPS (15.1 mm) (+/-1.05 SEM; P<0.01) in the maxilla and between GBAE (26.5 mm) and TPS (19.6 mm) (+/-1.42 SEM; P<0.01) in the mandible. Overall, the data indicate that, in the maxilla, screw-shaped implants showed more absolute BIC than cylindrical implants, which had less maxillary than mandibular absolute BIC after 18 months of functional loading.

Acid Etching, Dental↗

PubMed2005

The effect of platelet-rich plasma upon implant stability measured by resonance frequency analysis in the lower anterior mandibles.

Using a one-stage surgical protocol, a total of 34 Brånemark Mk-III Ti-Unite implants with a length of 13 mm and a diameter of 3.75 mm were inserted in 10 edentulous mandibles. Of these, seven patients received four and three patients two interforaminal implants. All implants were followed with repeated stability measurements by means of resonance frequency analysis at different time interval: 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44 days. In quadrant III platelet-rich plasma (PRP) was instilled locally before implant placement, while no PRP was added in quadrant IV to serve as control group (split-mouth design). Results showed no statistically significant difference between the two groups. Nonetheless, both groups (PRP+control) showed a highly significant reduction of the implant stability quotient (P<0.001) between days 0 and 4. However, no difference was noted between the two groups after day 4, it may be concluded that the instillation of PRP during implant placement in the lower anterior mandible did not add additional benefit.

Aged↗

PubMed2005

Evaluation of soft tissue around single-tooth implant crowns: the pink esthetic score.

AIM: In this study, the reproducibility of a newly developed pink esthetic score (PES) for evaluating soft tissue around single-tooth implant crowns was assessed. The effect of observer specialization was another point of interest. MATERIAL AND METHODS: Twenty observers (five prosthodontists, five oral surgeons, five orthodontists and five dental students) were given photographs of 30 single-tooth implant crowns. Seven variables were evaluated vs. a natural reference tooth: mesial papilla, distal papilla, soft-tissue level, soft-tissue contour, alveolar process deficiency, soft-tissue color and texture. Using a 0-1-2 scoring system, 0 being the lowest, 2 being the highest value, the maximum achievable PES was 14. Each observer was requested to make two assessments at an interval of 4 weeks. At the second assessment, the photographs were scored in the reverse order. RESULTS: The mean PES of evaluations at the first assessment (n=600) was 9.46 (+/-3.81 SD), and 9.24 (+/-3.8 SD) at the second one. The difference between these two means was not significant statistically (P=0.6379). Implant-related mean PES for single-tooth implants varied from 2.28 to 13.8, with standard deviations between 0.46 and 3.51. Very poor and very esthetic restorations showed the smallest standard deviations. The mean total PES was 10.6 for the prosthodontists, 9.2 for the oral surgeons, 9.9 for the dental students and 7.6 for the orthodontists. CONCLUSIONS: The PES reproducibly evaluates peri-implant soft tissue around single-tooth implants. Thus, an objective outcome of different surgical or prosthodontic protocols can be assessed. Orthodontists were clearly more critical than the other observers.

Adult↗

PubMed2004

Dental CT and orthodontic implants: imaging technique and assessment of available bone volume in the hard palate.

PURPOSE: Palatal implants (PI) have been introduced for orthodontic treatment of dental and skeletal dysgnathia. Due to the restricted amount of bone in this region, precise preoperative anatomic information is necessary. The aim of this study was to determine whether dental CT could serve as a tool to locate the optimal size and position for orthodontic implant placement. MATERIALS AND METHODS: In 32 patients, where palatal implant placement was planned, axial CT scans of the maxillary bone were acquired. Using a standard dental software package (Easy Vision dental software package 2.1, Philips; Best, The Netherlands), paracoronal views were reconstructed and measurements of palatal bone height in 3 mm increments, dorsally from the incisive canal, were performed in the median and both paramedian regions. RESULTS: The overall mean bone height was 5.01 mm (S.D. 2.60), ranging from 0 to 16.9 mm. The maximum palatal bone height was 6.17 mm (S.D. 2.81) at 6 mm dorsally from the incisive canal. Due to the lack of adequate bone (less than 4 mm), implant placement was not performed in 3 cases (7%). In the remaining 39 cases (93.0%), primary implant stability was achieved and complications, such as perforation of the palate, could be avoided. CONCLUSION: The results demonstrate that dental CT promises to be a valuable tool in evaluating the potential and optimal size and site for orthodontic implant placement.

Adolescent↗

PubMed2004

Effects of fibrin sealant protein concentrate with and without platelet-released growth factors on bony healing of cortical mandibular defects. An experimental study in minipigs.

In this study, the effects of fibrin sealant protein concentrate (FSPC; from the Tissucol Kit, Baxter, Vienna, Austria) with and without platelet-released growth factors (PRGF) on bony healing of cortical mandibular defects were investigated. Defects made in the facial mandibular wall of eight adult minipigs with a hollow drill were filled with FSPC alone, a mix of FSPC+PRGF or left untreated as controls. The animals were killed 4 and 8 weeks later. Specimens were processed for histology with the Donath method (1988) and stained with the Levai-Laczko stain. On histology, periosteal osteoneogenesis exceeded endosteal bone formation. No difference was seen in bone formation between FSPC alone, FSPC+PRGF and the controls at 4 and 8 weeks. On histomorphometry, there was no significant difference between the three groups in terms of the percent of newly formed bone at 4 and 8 weeks (P=0.6977). This study showed that FSPC neither increased nor decreased the amount of newly formed bone vs. controls and that the addition of PRGF had no effects on bone regeneration of cortical minipig bone at 4 and 8 weeks.

Animals↗