Paul J W Stoelinga

Publications of Paul J W Stoelinga

• A prospective study on the effect of modified alar cinch sutures and V-Y closure versus simple closing sutures on nasolabial changes after Le Fort I intrusion and advancement osteotomies.

  Authors: Marvick S M Muradin, Karlien Seubring, Paul J W Stoelinga, Andries vd Bilt, Ronald Koole, Antoine J W P Rosenberg

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 03/2011; 69(3):870-6.

  The purpose of this study was to determine whether a modified alar cinch suture and V-Y closure (mACVY) have a beneficial effect on labial form after Le Fort I intrusion and advancement osteotomiesThe purpose of this study was to determine whether a modified alar cinch suture and V-Y closure (mACVY) have a beneficial effect on labial form after Le Fort I intrusion and advancement osteotomies and whether they result in excessive upward nasal tip rotation. Both are possible effects compared with simple closing sutures (SCS). A prospective study was carried out on 56 patients, 31 with mACVY and 25 with SCS. Lateral cephalograms taken immediately before and 18 months after operation were used, measuring horizontal and vertical changes of the following landmarks: anterior and posterior nasal spine, A-point, incision superior, pronasale, subnasale, labiale superior, and stomion superior, as well as angular changes of sella-nasion-pronasale, and changes in upper vermilion exposure. Statistical analysis was performed on intragroup, paired t test, and intergroup differences, unpaired t test (P < .05). The horizontal and vertical changes of labiale superior were significantly larger for mACVY versus SCS, and the angle sella-nasion-pronasale increased in mACVY versus SCS. However, no significant difference was found for vertical changes of the nasal tip. Upper vermilion exposure increased with mACVY versus SCS. mACVY has a beneficial effect on labial form, and excessive upward rotation of the nasal tip is prevented.

• Reconstruction of the mandible using preshaped 2.3-mm titanium plates, autogenous cortical bone plates, particulate cancellous bone, and platelet-rich plasma: a retrospective analysis of 20 patients.

  Authors: Robert E C M Mooren, Matthias A W Merkx, Peter A W H Kessler, John A Jansen, Paul J W Stoelinga

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 10/2010; 68(10):2459-67.

  The purpose of this retrospective study was to evaluate a group of 20 patients who underwent a reconstruction of the mandible by use of free bone grafts and platelet-rich plasma (PRP). In a period ofThe purpose of this retrospective study was to evaluate a group of 20 patients who underwent a reconstruction of the mandible by use of free bone grafts and platelet-rich plasma (PRP). In a period of 8 years, 20 patients underwent a reconstruction of the mandible, by use of preshaped 2.3-mm titanium plates, autogenous cortical bone plates, autogenous particulate bone, PRP, and a special fixation technique. The patients were divided into 3 groups. Group 1 consisted of 10 patients who underwent secondary reconstruction after ablative surgery for malignant tumors. Of these, 4 had preoperative or postoperative radiotherapy. Group 2 comprised 7 patients who underwent primary reconstruction after resections for benign but aggressive odontogenic tumors. Group 3 consisted of 3 patients with severe atrophy and malunion. The defects ranged in size from 8 to 12 cm in groups 1 and 2 and from 2 to 4 cm in group 3, and the follow-up ranged from 1 to 8 years. The initial healing was uneventful in all but 3 patients. In these 3 patients additional bone grafts had to be placed to allow for optimal implant placement. At the time of implant insertion, some areas of granulation tissue were found, possibly because of the rather high dose of PRP used. Continuity in all cases was achieved, and the patients considered the results good in 10 cases and satisfactory in 9 cases. One patient could not be approached for the last assessment. The grafting and fixation technique used proved to be rather reliable. The antimicrobial effect and the proliferation of osteoblasts are likely to be responsible for the results achieved.

• The effect of platelet-rich plasma in vitro on primary cells: rat osteoblast-like cells and human endothelial cells.

  Authors: Robert E C M Mooren, Eef J Hendriks, Jeroen J J P van den Beucken, Mathijs A W Merkx, Gert J Meijer, John A Jansen, Paul J W Stoelinga

  Tissue engineering. Part A. 10/2010; 16(10):3159-72.

  The aim of this study was to evaluate the effects of standardized platelet-rich plasma (PRP) concentrates from 10 human donors on cellular behavior. The standardized PRPs used were fivefold averageThe aim of this study was to evaluate the effects of standardized platelet-rich plasma (PRP) concentrates from 10 human donors on cellular behavior. The standardized PRPs used were fivefold average and fivefold maximum baseline values in whole blood. Both these standardized PRPs were characterized by determining platelet numbers and subsequently growth factor concentrations in activated PRPs, called PRP derivatives. Platelet numbers in both types of standardized PRPs were significantly increased compared with whole blood. Further, both PRP derivatives contained significantly higher concentrations of platelet-derived growth factor-AA, platelet-derived growth factor-AB, and transforming growth factor-beta 1. Vascular endothelial growth factor concentrations were significantly elevated in only the most concentrated PRP derivative. Cell culture experiments with osteoblast-like cells showed that both PRP derivatives stimulated cell proliferation without inducing cell differentiation, whereas tube formation in endothelial cell cultures was significantly increased by adding low volume percentages of PRP derivative (2%–8%). Consequently, it can be concluded that there is no direct relationship between the number of platelets and the level of growth factors released from these platelets. PRP derivatives have the potency to stimulate angiogenesis dose dependently, while lacking the capacity to induce osteogenic differentiation. Yet, the proliferation of osteoblast-like cells can significantly be enhanced by supplementation of PRP derivatives.

• Replacement of the condyle and ascending ramus by a modular endoprosthesis in Macaca fascicularis--part 4: evaluation of the temporomandibular joints.

  Authors: Bee Tin Goh, Shermin Lee, Henk Tideman, John A Jansen, Paul J W Stoelinga

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 09/2010; 68(9):2136-45.

  To assess, using cone-beam computed tomography and histologic examination, whether the fixation of a condyle-ascending ramus mandibular modular endoprosthesis results in a physiologic condylarTo assess, using cone-beam computed tomography and histologic examination, whether the fixation of a condyle-ascending ramus mandibular modular endoprosthesis results in a physiologic condylar replacement in Macaca fascicularis. The right condyle and ascending ramus were resected in 8 adult monkeys and replaced with a modular endoprosthesis, fixed with polymethyl methacrylate bone cement (Palacos). Four monkeys were sacrificed at 3 months and another 4 at 6 months postoperatively. The reconstructed and contralateral temporomandibular joints were harvested en bloc and studied using cone-beam computed tomography and descriptive histologic examination. Heterotopic bone formation was quantified using a modified grading scale. The condyle cartilage thickness in the contralateral temporomandibular joint was measured using histomorphometric methods. The results were compared with those of the unoperated control monkeys. Bone resorption in the glenoid fossa and pathologic changes in the articular disc were noted on the reconstructed side in most specimens. Nevertheless, cone-beam computed tomography findings, histologic findings, and condyle cartilage thickness measurements of the contralateral temporomandibular joint were not significantly different from those of the control specimens. Replacement of the condyle and ascending ramus using a modular endoprosthesis in Macaca fascicularis resulted in adaptive remodeling of the glenoid fossa at up to 6 months postoperatively. Long-term studies are required to further assess the potential of this mode of reconstruction.

• Replacement of the condyle and ascending ramus by a modular endoprosthesis in Macaca fascicularis--part 3: evaluation of peri-implant bone remodeling.

  Authors: Bee Tin Goh, Shermin Lee, Henk Tideman, Paul J W Stoelinga, John A Jansen

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 08/2010; 68(8):1776-82.

  To assess whether the fixation of a condyle-ascending ramus mandibular modular endoprosthesis, using bone cement, will result in stress-related bone resorption in the Macaca fascicularis. The rightTo assess whether the fixation of a condyle-ascending ramus mandibular modular endoprosthesis, using bone cement, will result in stress-related bone resorption in the Macaca fascicularis. The right condyle and ascending ramus were resected in 8 adult monkeys and replaced by a modular endoprosthesis, fixed with polymethylmethacrylate bone cement (Palacos). Four monkeys were sacrificed at 3 months and another 4 at 6 months postoperatively. The bone mineral density was assessed using dual-energy x-ray absorptiometry in the region anterior to the stem and using micro-computed tomography in the buccal, lingual, and inferior regions adjacent to the stem. The bone mineral density of the 3-month specimens was greater than that at 6 months in the buccal, lingual, and inferior regions adjacent to the stem. However, the difference was statistically significant only in the inferior aspect. No significant difference was found in the bone mineral density in the region anterior to the stem between the 3- and 6-month specimens. A minimal reduction in bone density around the stem of the endoprosthesis was observed between 3 and 6 months after placement. This reduction did not result in any adverse clinical events.

• Replacement of the Condyle and Ascending Ramus by a Modular Endoprosthesis in Macaca fascicularis-Part 2: Microcomputed Tomographic and Histologic Evaluation of the Ramus and Stem.

  Authors: Bee Tin Goh, Shermin Lee, Henk Tideman, John A Jansen, Paul J W Stoelinga

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 12/2009; 67(12):2617-2626.

  PURPOSE: The present study presents the microcomputed tomographic and histologic evaluation of the peri-implant tissues of a modular endoprosthesis used to replace the condyle and ascending ramus inPURPOSE: The present study presents the microcomputed tomographic and histologic evaluation of the peri-implant tissues of a modular endoprosthesis used to replace the condyle and ascending ramus in Macaca fascicularis. MATERIALS AND METHODS: The right condyle and ascending ramus were resected in 8 adult monkeys and replaced by a modular endoprosthesis, fixed with polymethylmethacrylate bone cement (Palacos). Four monkeys were sacrificed at 3 months and 4 at 6 months postoperatively. Microcomputed tomographic scanning was performed to analyze the bone volume at the bone-cement interface. Histologic and histomorphometric assessments were done using a modified hard and soft tissue grading scale and by studying the total bone contact at the interface. RESULTS: The combined (buccal, lingual, and inferior) mean bone volume percentage of the 6-month group was significantly greater than that of the 3-month group (P < .05). The 6-month specimens showed a reduced inflammatory response and more abundant bone formation around the stem. The total soft tissue histologic score was significantly greater in the 6-month group (P < .05). A total bone contact percentage of 15.4% to 85.2% was achieved in 3 specimens. CONCLUSIONS: Satisfactory bone growth was found at the bone-cement interface at the stem region, although direct bone contact with the cement was not achieved in all cases. Soft tissue contact with the prosthetic ramus, in the form of a fibrous capsule, was present in some areas. At 6 months, minimal interfacial inflammation was found in this monkey model.

• The evaluation of mineralized collagen as a carrier for the osteoinductive material COLLOSS(R)E, in vivo.

  Authors: Marloes Nienhuijs, X Frank Walboomers, Michael Gelinsky, Paul J W Stoelinga, John Jansen

  Tissue engineering. Part A. 11/2009;

  In this study the suitability of mineralized collagen, as a carrier for the native bone morphogenetic protein (BMP) containing product COLLOSS(R)E, was evaluated in a rat subcutaneous implantationIn this study the suitability of mineralized collagen, as a carrier for the native bone morphogenetic protein (BMP) containing product COLLOSS(R)E, was evaluated in a rat subcutaneous implantation model. Tubular shaped scaffolds were made from mineralized collagen and either left empty (controls), filled with 40 mg COLLOSS(R)E, or filled with a mixture of COLLOSS(R)E and osteoconductive beta tricalcium phosphate (beta-TCP) granules. Six of all samples were implanted in 18 animals. During the implantation period, macroscopic examination suggested inflammatory reaction. Histological evaluation after 12 weeks confirmed the presence of inflammatory cells. Although the mineralized scaffold and beta-TCP granules could clearly be seen, no new bone formation was found. This is in contrast to previous reports in a similar set-up, using a titanium mesh as scaffold material in combination with COLLOSS(R)E. It is concluded, therefore, that the osteoinductive capacity of BMPs or more specifically COLLOSS(R)E is inhibited when the carrier gives rise to a significant inflammatory reaction. Additional studies are necessary to assess the effect of combining COLLOSS(R)E with a dimensionally stable and osteoconductive material like beta-TCP.

• Replacement of the condyle and ascending ramus by a modular endoprosthesis in Macaca fascicularis--part 1: a clinical and radiographic study.

  Authors: Bee Tin Goh, Shermin Lee, Henk Tideman, Paul J W Stoelinga

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 08/2009; 67(7):1392-400.

  PURPOSE: To evaluate the feasibility of replacing the condyle and ascending ramus with a novel modular endoprosthesis in Macaca fascicularis. MATERIALS AND METHODS: Eight male adult monkeys (MacacaPURPOSE: To evaluate the feasibility of replacing the condyle and ascending ramus with a novel modular endoprosthesis in Macaca fascicularis. MATERIALS AND METHODS: Eight male adult monkeys (Macaca fascicularis) were used in this study. The right condyle and ascending ramus posterior to the lower second molar were resected. An endoprosthesis consisting of 2 modules was inserted to replace the resected segment and fixed in place using polymethylmethacrylate bone cement (Palacos). Four monkeys were sacrificed at 3 months and another 4 at 6 months postoperatively. The operated side of the mandible was then harvested, including the endoprosthesis and the stump of the mandible to which it was attached. Lateral mandibular radiographs were taken using standard settings immediately postoperatively and postsacrifice. RESULTS: Two monkeys presented with a fistula at the operated area 1 month postoperatively, but this resolved with a short course of antimicrobial treatment. At the time of sacrifice, no fistulas, dehiscences, or mobility of the endoprostheses was observed. There was no significant change in maximum mouth opening. At 3 months, a linear radiolucency was noted at the cement-bone interface in the 2 monkeys that previously presented with fistulas; whereas at 6 months, none of the 4 animals showed any radiolucency. CONCLUSIONS: The use of a cemented modular endoprosthesis for replacement of the condyle and ramus unit was feasible with minimal complications allowing normal mouth opening and occlusion. Further histologic and microfocus computed tomographic studies will be done to confirm the findings.

• Assessment of bone vascularity in the anterior mandible using laser Doppler flowmetry.

  Authors: Henk W D Verdonck, Gert J Meijer, Peter Kessler, Fred H Nieman, Cees de Baat, Paul J W Stoelinga

  Clinical oral implants research. 01/2009;

  Abstract Objectives: In irradiated bone, a method assessing vascularity of intended implant recipient bone would be of clinical significance in preventing early implant loss and in reducing the riskAbstract Objectives: In irradiated bone, a method assessing vascularity of intended implant recipient bone would be of clinical significance in preventing early implant loss and in reducing the risk of osteoradionecrosis due to surgical oral implant insertion. At present, assessing bone vascularity clinically, using laser Doppler flowmetry (LDF), seems to be realistic. The hypotheses of this study were that bone vascularity in the human anterior mandible can be assessed during implant insertion by LDF and that the recorded LDF values are providing standard data for bone vascularity in the human anterior mandible. Material and methods: Twenty-three randomly selected non-irradiated edentulous patients scheduled for treatment with oral implants in the anterior mandible were assigned, 12 men and 11 women. The patients' history of edentulousness and resorption of the residual alveolar ridges were registered. In pilot osteotomy sites of planned implant insertion, the bone vascularity was registered, using LDF and expressed in perfusion units (PU). The statistical distribution and characteristics of the LDF values were explored, separately for men and women. Results: A total of 41 pilot osteotomy sites were recorded with a mean LDF value of 25.80 PU. No obvious gender difference was found and LDF values did not show a relationship with patient's age or history of edentulousness. Conclusion: The hypotheses that bone vascularity in the human anterior mandible can be assessed during implant insertion by LDF and that the recorded LDF values are providing standard data for bone vascularity in the human anterior mandible, were confirmed. To cite this article: Verdonck HWD, Meijer GJ, Kessler P, Nieman FH, de Baat C, Stoelinga PJW. Assessment of bone vascularity in the anterior mandible using laser Doppler flowmetry. Clin. Oral Impl. Res. xx, 2008; 000-000.

• Intensity-modulated radiation therapy for oropharyngeal cancer: Radiation dosage constraint at the anterior mandible.

  Authors: Henk W D Verdonck, Jos M A de Jong, Marlies E P G Granzier, Fred H Nieman, Cees de Baat, Paul J W Stoelinga

  Oral oncology. 10/2008;

  Because the survival of endosseous implants in irradiated bone is lower than in non-irradiated bone, particularly if the irradiation dose exceeds 50Gy, a study was carried out to assess theBecause the survival of endosseous implants in irradiated bone is lower than in non-irradiated bone, particularly if the irradiation dose exceeds 50Gy, a study was carried out to assess the irradiation dose in the anterior mandible, when intensity modulated radiation therapy (IMRT) is used. The hypothesis was that adequate IMRT planning in oropharyngeal cancer patients is allowing sufficiently low anterior mandibular bone radiation dosages to safely insert endosseous implants. Ten randomly selected patients with oropharyngeal cancer, primarily treated by intensity-modulated radiotherapy (IMRT), were included in this study. First, at five determined positions distributed over the anterior mandible, the appropriate radiation dosages were calculated according to the originally arranged fractionated radiation schedule. Second, for each patient an adjusted fractionated radiation schedule was established with an extra dose constraint which allowed a lower dose in the mandible taking into account that the anterior mandible needs protection against radiation-induced osteoradionecrosis. The goal for the adjusted fractionated radiation schedule was similar as that of the original fractionated radiation schedule, including a desired tumour target dosage of 70Gy and maximum mean local dosages for organs at risk. The data revealed a considerable and statistically significant, irradiation dose reduction in the anterior mandible without compromising the other constraints. As a result of this study it is strongly advised to maximize dose constraint to the anterior mandible when planning irradiation for oropharyngeal cancer patients, using IMRT. This would greatly facilitate successful implant treatment for this group of patients. The fractionated radiation schedules used, should also be used for the planning of the best implant positions by integrating them in the implant planning software.

• Mandibular reconstruction in adults: a review.

  Authors: Bee Tin Goh, Shermin Lee, Henk Tideman, Paul J W Stoelinga

  International journal of oral and maxillofacial surgery. 08/2008; 37(7):597-605.

  Mandibular defects may result from trauma, inflammatory disease and benign or malignant tumours. Mastication, speech and facial aesthetics are often severely compromised without reconstruction. TheMandibular defects may result from trauma, inflammatory disease and benign or malignant tumours. Mastication, speech and facial aesthetics are often severely compromised without reconstruction. The goal of mandibular reconstruction is to restore facial form and function, implying repair of mandibular continuity and muscle attachments. There should also be room for implant insertion so as to allow for rehabilitation of occlusion and articulation, whereas the function of the inferior alveolar nerve should be restored to assure adequate sensitivity of the lips. Mandibular reconstruction principles and techniques have evolved dramatically over the years. Refinements in techniques continue to improve patient quality of life. This paper reviews current techniques of mandibular reconstruction in adults and discusses the strengths and weaknesses of each.

• Quantitative dynamic contrast-enhanced MRI for the assessment of mandibular invasion by squamous cell carcinoma.

  Authors: Ellen M Van Cann, Mark Rijpkema, Arend Heerschap, Andries van der Bilt, Ron Koole, Paul J W Stoelinga

  Oral oncology. 05/2008;

  The objective of this study was to determine the value of dynamic contrast-enhanced MRI (DCE-MRI) for the preoperative assessment of mandibular invasion in squamous cell carcinomas (SCC), adjacent orThe objective of this study was to determine the value of dynamic contrast-enhanced MRI (DCE-MRI) for the preoperative assessment of mandibular invasion in squamous cell carcinomas (SCC), adjacent or fixed to the mandible. DCE-MRI was performed with gadolinium diethylene triamine pentaacetic acid (Gd-DTPA). Data were obtained from 25 patients. From pharmacokinetic analysis of the tissue uptake of Gd-DTPA, the DCE-MRI parameters (k(ep), K(trans) and v(e)) were determined, with k(ep) representing the exchange rate constant, K(trans) the volume transfer constant and v(e) the volume of extracellular space per unit volume of tissue. The histology of the resection specimens was used as gold standard for the extent of mandibular invasion. SCC with medullary invasion showed higher mean k(ep) and K(trans) compared with SCC without medullary invasion (ANOVA, p<0.001). ROC analysis of k(ep) and K(trans) revealed reliable threshold values for medullary invasion. In conclusion, DCE-MRI can discriminate SCC with medullary invasion from SCC without medullary invasion and may serve as a valuable tool in preoperative tumour staging with regard to the delineation of medullary invasion.

• Implant stability during osseointegration in irradiated and non-irradiated minipig alveolar bone: an experimental study.

  Authors: Henk W D Verdonck, Gert J Meijer, Thorsten Laurin, Fred H Nieman, Christian Stoll, Dieter Riediger, Paul J W Stoelinga, Cees de Baat

  Clinical oral implants research. 03/2008; 19(2):201-6.

  OBJECTIVES: Primary implant stability is related to local bone density. After insertion of an implant, implant stability is subject to changes due to bone remodeling. In patients who have undergoneOBJECTIVES: Primary implant stability is related to local bone density. After insertion of an implant, implant stability is subject to changes due to bone remodeling. In patients who have undergone radiotherapy in the head and neck region, implant stability is impaired because irradiation reduces bone vitality. The current study was designed to monitor and test implant stability immediately after implant placement and during osseointegration in irradiated and non-irradiated minipig alveolar bone. MATERIALS AND METHODS: All maxillary and mandibular premolars and molars of six adult Göttingen minipigs were extracted. The maxilla and mandible of three minipigs received three irradiation exposures at a total dose of 24 Gy. After irradiation, five initial implant holes were drilled in the residual alveolar ridge of each edentulous site. In order to assess bone vascularity, laser Doppler flowmetry recordings were carried out in the initial holes. A total of 120 implants were placed in the six minipigs. Subsequently, and at 8, 16, and 24 weeks after implant placement, implant stability was recorded by resonance frequency analysis (RFA). RFA values were expressed as an implant stability quotient (ISQ). RESULTS: ISQ values recorded immediately after implant placement showed no differences between irradiated and non-irradiated minipigs. Repeated measurements at the four recording moments showed a decrease of ISQ values in all minipigs, being more pronounced in irradiated bone, when compared with non-irradiated bone. The results at the third and fourth recording moments showed a stabilization or even a slight increase of ISQ values. CONCLUSIONS: The results document the negative effect of irradiation on bone vascularity and hence on implant stability.

• Platelet-rich plasma: quantification of growth factor levels and the effect on growth and differentiation of rat bone marrow cells.

  Authors: Juliette van den Dolder, Rob Mooren, Annelies P G Vloon, Paul J W Stoelinga, John A Jansen

  Tissue engineering. 12/2006; 12(11):3067-73.

  Platelet-rich plasma (PRP) is a new application of tissue engineering and a developing area for clinicians and researchers. It is a storage vehicle of growth factors (GFs) such as platelet-derivedPlatelet-rich plasma (PRP) is a new application of tissue engineering and a developing area for clinicians and researchers. It is a storage vehicle of growth factors (GFs) such as platelet-derived growth factor (PDGF)- AA, -BB, -AB; transforming growth factor (TGF)-beta1 and -2; platelet-derived epidermal growth factor (PDEGF); platelet-derived angiogenesis factor (PDAF); insulin growth factor-1 (IGF-1); and platelet factor- 4 (PF-4), which are known to influence bone regeneration. However, animal and clinical studies reveal different results with the use of PRP and its effect on bone healing. This could be due to the differences between species, that is, differences between species in GF concentrations or variation in presence of GFs between the various PRPs. In this study, rat bone marrow cells were cultured in PRP-coated wells or in uncoated wells for 16 days in osteogenic medium, and analyzed on cell growth (DNA content) and cell differentiation (alkaline phosphatase [ALP] activity, calcium content, scanning electron microscopy, and QPCR). The concentrations of TGF-beta1, PDGF-AA, PDGF-AB, and PDGF-BB in rat, goat, and human PRP were subsequently determined. The results showed that PRP stimulated initial cell growth and had no effect on ALP activity. The calcium measurements showed a significant increase in calcium at days 8, 12, and 16. The real-time PCR results showed that PRP upregulated osteocalcin at day 1 and collagen type I at day 8. Overall, the immunoassays revealed that human PRP contained higher concentrations of growth factors per platelet compared to rat and goat PRP. Goat PRP showed higher concentrations of growth factors per platelet as compared to rat PRP except for PDGF-BB, which had a higher concentration in rat PRP. TGF-beta1 was the most abundant growth factor in all 3 PRPs. On the basis of our results, we conclude that platelet-rich plasma contains osteo-inductive growth factors, which are probably species related. However, we cannot generalize the results because of large intraspecies variations. Further, we conclude that rat PRP gel stimulates initial growth and differentiation of rat bone marrow cells in vitro.

• The effect of platelet-rich plasma on the bone healing around calcium phosphate-coated and non-coated oral implants in trabecular bone.

  Authors: Dimitris Nikolidakis, Juliette van den Dolder, Joop G C Wolke, Paul J W Stoelinga, John A Jansen

  Tissue engineering. 10/2006; 12(9):2555-63.

  The effect of local application of autologous platelet-rich plasma (PRP) on bone healing in combination with the use of titanium implants with 2 different surface configurations was investigated. PRPThe effect of local application of autologous platelet-rich plasma (PRP) on bone healing in combination with the use of titanium implants with 2 different surface configurations was investigated. PRP fractions were obtained from venous blood sample of 6 goats and applied via gel preparation and subsequent installation in the implant site or via dipping of the implant in PRP liquid before insertion. Thirty-six implants (18 non-coated and 18 calcium phosphate (CaP) coated) were placed into the goat femoral condyles (trabecular bone). The animals were sacrificed at 6 weeks after implantation, and implants with surrounding tissue were processed for light microscopical evaluation. In addition to subjective description of the histological findings, histomorphometrical variables were also evaluated (the bone-implant contact and the bone mass adjacent to the implant). Significantly more interfacial bone-to-implant contact was observed for all 3 groups of CaP-coated implants and the titanium / liquid group (non-coated implant with PRP liquid) than for the other 2 non-coated titanium groups (with PRP gel or without PRP). The evaluation of the bone mass close to implant surface indicated that all the groups induced a significant increase of the bone mass except the PRP gel groups. On the basis of the observations, it was concluded that magnetron-sputtered CaP coatings can improve the integration of oral implants in trabecular bone. The additional use of PRP did not offer any significant effect on the bone response to the CaP-coated implants, whereas PRP in a liquid form showed a significant effect on bone apposition to roughened titanium implants during the early post-implantation healing phase.

• Bone-like tissue formation using an equine COLLOSS E-filled titanium scaffolding material.

  Authors: Marloes E L Nienhuijs, X Frank Walboomers, Matthias A W Merkx, Paul J W Stoelinga, John A Jansen

  Biomaterials. 07/2006; 27(16):3109-14.

  COLLOSS, a bovine extracellular matrix product containing native BMPs has already shown osteoinductive properties. To overcome problems with risk of transmissable spongiform encephalopathy (TSE)COLLOSS, a bovine extracellular matrix product containing native BMPs has already shown osteoinductive properties. To overcome problems with risk of transmissable spongiform encephalopathy (TSE) infection, an equine derived version was investigated in this study, named COLLOSS E. Disc- and tube-shaped implants were made from titanium fibre mesh. The central space of tubes was filled and the discs were impregnated with the COLLOSS E material to assess osteo-induction. These implants and non-loaded controls were implanted subcutaneously into the back of Wistar rats. After implantation periods of 2, 8, and 12 weeks, the implants were retrieved and sections were made. Histology showed a thin fibrous capsule surrounding the titanium mesh and a very mild tissue reaction. The disc implants, loaded or non-loaded, showed no bone formation at all. After 2 weeks of implantation 3 out of 5 of the loaded tubes showed bone formation with a mean of 0.3 mm2 areas of new formed bone, after 8 weeks 3 out of 6 and 0.7 mm2, and after 12 weeks this increased to 6 out of 6 and 1.0 mm2. In the non-loaded tubes only connective tissue in growth was seen. In conclusion, it was demonstrated that COLLOSS E material, loaded in a titanium fibre mesh tube shows osteoinductive properties. The effect of COLLOSS E has to be investigated further in orthotopic sites, which resemble more the final clinical application for bone reconstruction.

• Bone SPECT reduces the number of unnecessary mandibular resections in patients with squamous cell carcinoma.

  Authors: Ellen M Van Cann, Wim J G Oyen, Ron Koole, Paul J W Stoelinga

  Oral oncology. 05/2006; 42(4):409-14.

  High percentages (35-78%) of resected mandibles without bone invasion have been reported in squamous cell carcinoma (SCC), adjacent or fixed to the mandible, stressing the need for accurate imagingHigh percentages (35-78%) of resected mandibles without bone invasion have been reported in squamous cell carcinoma (SCC), adjacent or fixed to the mandible, stressing the need for accurate imaging methods. The aim of this study is to determine the value of bone single photon emission computed tomography (SPECT) for the evaluation of mandibular invasion by SCC. Seventy-nine patients with SCC, adjacent or fixed to the mandible, were included. The results of bone SPECT were compared to the histology of the resection specimens. Bone SPECT was positive in all 50 patients with mandibular invasion and negative in 17 of 29 patients without mandibular invasion. In conclusion, a negative bone SPECT rules out mandibular invasion. Important clinical implications are then that further imaging is not necessary and that the resection can be kept limited. Inclusion of SPECT in the preoperative assessment of these patients will lead to a considerable reduction of unnecessary mandibular resections.

• The treatment of odontogenic keratocysts by excision of the overlying, attached mucosa, enucleation, and treatment of the bony defect with carnoy solution.

  Authors: Paul J W Stoelinga

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 12/2005; 63(11):1662-6.

• Health related quality of life after mandibular resection for oral and oropharyngeal squamous cell carcinoma.

  Authors: Ellen M Van Cann, Marc Dom, Ron Koole, Matthias A W Merkx, Paul J W Stoelinga

  Oral oncology. 09/2005; 41(7):687-93.

  The impact of several clinical parameters on health related quality of life (HrQOL) was evaluated in patients with squamous cell carcinoma adjacent or fixed to the mandible with special emphasis onThe impact of several clinical parameters on health related quality of life (HrQOL) was evaluated in patients with squamous cell carcinoma adjacent or fixed to the mandible with special emphasis on postoperative radiotherapy and type of mandibular resection. One-hundred and five returned EORTC-questionnaires were available for this study. Correlation analyses were used to determine the relationship between clinical parameters and HrQOL. Postoperative radiotherapy was the clinical parameter that affected HrQOL most. The type of mandibular resection had no influence on HrQOL. The affected QOL-items were all associated with eating problems, i.e. use of a feeding tube, use of nutritional supplements, swallowing, social eating, mouth opening and dry mouth. Postoperative radiotherapy should only be applied if strictly indicated. This implies that the application of postoperative radiotherapy may need reconsideration in cases without strict criteria for postoperative radiotherapy.

• The influence of the sagittal split osteotomy on the condylar cartilage structure and the subchondral vascularization of the temporomandibular joint: a preliminary study in goats.

  Authors: Wilfred A Borstlap, Jaap C Maltha, Paul J W Stoelinga, Johannes W Von den Hoff

  Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics. 09/2005; 100(2):138-45; discussion 146.

  OBJECTIVE: The concern that a sagittal split osteotomy of the mandibular ramus could compromise the subchondral vascularization and especially the venous outflow in the condylar area, which in turnOBJECTIVE: The concern that a sagittal split osteotomy of the mandibular ramus could compromise the subchondral vascularization and especially the venous outflow in the condylar area, which in turn could influence the structure of the condylar cartilage, prompted this preliminary study on goats. STUDY DESIGN: A sagittal split osteotomy was performed in the mandibular ramus at 1 side in each of 6 young adult goats. The contralateral side served as control. The animals were killed after different postoperative periods, ranging from 1 to 15 days. Histomorphometric analyses were performed after perfusion of the vascular system with India ink. CONCLUSION: Based on the observed cartilage thickening, the sagittal split osteotomy may influence the condylar cartilage in the first days postoperatively through a disturbance of the vascular supply.